Cyclomodulins and Some Microbial Metabolites in Bacterial Microecology

Version	Summary	Created by	Modification	Content Size	Created at	Operation
1		Natalia Markelova	--	4217	2022-10-13 14:12:45

This entry is adapted from the peer-reviewed paper 10.3390/ijms231911706

A number of bacteria that colonize the human body produce toxins and effectors that cause changes in the eukaryotic cell cycle—cyclomodulins and low-molecular-weight compounds such as butyrate, lactic acid, and secondary bile acids. Cyclomodulins and metabolites are necessary for bacteria as adaptation factors—which are influenced by direct selection—to the ecological niches of the host. In the process of establishing two-way communication with the macroorganism, these compounds cause limited damage to the host, despite their ability to disrupt key processes in eukaryotic cells, which can lead to pathological changes. Possible negative consequences of cyclomodulin and metabolite actions include their potential role in carcinogenesis, in particular, with the ability to cause DNA damage, increase genome instability, and interfere with cancer-associated regulatory pathways.

cyclomodulins genotoxins bacterial metabolites microecology carcinogenesis

1. Introduction

Epidemiological studies often reveal strong links between bacterial pathogens and cancer incidence: between Helicobacter pylori and gastric cancer; between Salmonella typhi and gallbladder carcinoma; between Salmonella enteritidis and colon carcinoma. Therein, many bacterial factors have been identified that mediate the malignant transformation of host cells: toxins, cell surface components, and effector proteins. Frequently, these factors target eukaryotic cell signaling pathways; interference with these pathways leads to cancer development ^[1]. Thus, many bacterial pathogens affect the Wnt/β-catenin signaling pathway, resulting in the induction of the β-catenin release. β-catenin penetrates the nucleus and activates the Wnt pathway genes to control the transcription of genes involved in apoptosis, cell proliferation, and malignant transformation ^[2]^[3]. Bacterial surface molecules can perform as activators, for example, Fusobacterium nucleatum adhesin FadA, which can bind to E-cadherin, inducing the release of β-catenin ^[4]. The S. enteritidis AvrA effector protein stabilizes β-catenin, which leads to Wnt signaling, and inhibits JNK and NF-κβ signaling pathways involved in inflammation and apoptosis ^[1]. The CagA toxin of H. pylori forms a functional CagA-c-Met-CD44 complex by activating Wnt/β-catenin, which induces the accumulation of nuclear β-catenin by activating PI3K/Akt signaling, resulting in the inhibition of apoptosis. Bacteroides fragilis toxin (BFT) causes dissociation of β-catenin from E-cadherin; the complex of β-catenin with TCF4 leads to c-Myc expression and cell proliferation ^[3]. No less significant bacterial factors associated with the malignant transformation of eukaryotic cells are toxins and effectors that cause changes in the eukaryotic cell cycle, for which they received their name—cyclomodulins. The cell cycle is one of the most favorable targets for toxins and effectors because basic cell functions are disrupted, which creates favorable conditions for bacterial invasion and colonization of the host. Cell cycle arrest at the G2/M phase by some cyclomodulins leads to disruption of cell renewal, induces delayed apoptosis of host cells, or blocks it. This increases the bacterial replication time and promotes colonization of the host, but at the same time can lead the cells to malignant transformation. Cyclomodulins of many commensal bacteria induce cell cycle arrest at the G2/M phase, creating a favorable environment for themselves without causing significant harm to the host ^[5].

The ecology of bacteria occupying the niches of mucous membranes and skin is associated with the colonization of these surfaces by commensals and pathogens, which, in the course of a long evolution, have developed various survival strategies both in the microbial environment and in the macro-organism ^[6]. Cyclomodulins are directly related to one of the survival strategies of bacteria. This strategy is based on causing limited damage to host cells, which disrupts their normal functions and defense against the pathogenic potential of the bacteria themselves. ^[7]^[8]. These cyclomodulins include cytotoxic necrotizing factors (CNFs), which prevent cytokinesis and simultaneously stimulate the cell cycle and DNA replication; cycle inhibitory factors (CIFs) that block the cell cycle and slow down apoptosis by inhibiting the proteasomal degradation pathway; DNA-damaging genotoxins, including a low-molecular-weight substance colibactin and protein cytolethal distending toxin (CDT) ^[9]^[10]^[11]^[12]. By modulating cell differentiation, apoptosis, and proliferation, cyclomodulins slow down the renewal of the epithelium, contributing to the prolonged colonization of macroorganism biotopes by the bacteria producing them. At the same time, eukaryotic cells preserved after exposure to toxins acquire genomic instability, which can play a certain role in their malignant transformation ^[13]^[14].

Unlike bacteria that adapt to the host through the production of toxins affecting its cells, there is a different microbial survival strategy—inhibition of competing microorganisms with the help of microbial metabolites. Bacteria producers of a number of known compounds, such as butyrate, lactic acid and secondary bile acids, colonize various biotopes of the human body supporting different physiological processes. However, under conditions of disruption of the homeostasis of the macroorganism by external and internal factors, microbial metabolism can affect the occurrence and/or development of pathological conditions, including neoplasms ^[15]. Among the carcinogenic metabolites of bacteria, the most studied are hydrogen sulfide and secondary bile acids, as well as reactive oxygen intermediates capable of causing oxidative damage to DNA. While the role of secondary bile acids in carcinogenesis is known, the role of butyrate, lactate, and other derivatives of short-chain fatty acids is described mainly as protective against cancer development ^[3]. At the same time, studies emerge that prove their contribution to carcinogenesis.

2. Cyclomodulins—CNFs

CNFs are bacterial exotoxins of a protein nature that affect signal transduction in a eukaryotic cell, modulating cytokinetic processes. CNFs activate GTP-binding proteins of the Rho family (Rho GTPases): Rho (A, B, C) Rac, Cdc42 in cells via deamidation of glutamine (Q61 or Q63) at the Rho active site; as a result, Rho proteins lose the ability to hydrolyze the Rho-bound GTP ^[16]^[17]. Activation of Rho GTPase proteins blocks key regulators of cellular processes in their active state, causing changes in the actin cytoskeleton, cell proliferation, production of reactive oxygen species (ROS), and release of anti-apoptotic and pro-inflammatory factors ^[18]^[19].

CNF toxins are secreted and bind to eukaryotic cell surface receptors, causing endocytosis and subsequent translocation of the catalytic subunit into the cytosol. CNFs were found in Escherichia coli, Yersinia pseudotuberculosis, Shigella species, and Salmonella enterica. CNF1 is the most studied toxin produced by some strains of E. coli and is more common among uropathogenic E. coli living in the intestine and penetrating into the urinary tract through the urethra ^[9]^[17]^[20].

CNF toxins activate Rho GTPases, which, through the Akt/IkB kinase pathway, positively regulate the activity of NFkB, which in turn translocates from the cytoplasm to the nucleus and promotes transcription of the anti-apoptotic factors Bcl-2 and Bcl-XL and cell survival ^[7]^[21]. Protecting epithelial cells from apoptosis, CNF1 slows down their renewal, which leads to the colonization of the epithelium by toxigenic bacteria. Other important events that occur under the influence of toxin-activated Rho GTPases are changes in the actin cytoskeleton through actin polymerization and blocking of cytokinesis with the formation of multinucleated cells as a result of ongoing DNA replication. Infected cells develop lamellipodia and filopodia, endowing them with phagocytic behavior and the ability to macropinocytosis, facilitating the internalization of bacteria into host cells ^[18]^[22].

CNF1′s potential role in carcinogenesis is also determined by its effect on eukaryotic cells (Figure 1). The absence of cytokinesis results in aneuploidy, which has been demonstrated by the treatment of the HCT 116 cell line with CNF1 toxin, the cell cycle reversibly arrested, and cell depolyploidization occurred. Their further entry into the cell cycle generated a large number of aneuploid progeny, which became more resistant to CNF1 ^[11]. Intercellular junctions disrupted under the influence of CNF1 improved the motility and migration of tumor cells, which can enhance their invasion and metastasis ^[18].

/media/item_content/202210/6348005eb1ca9ijms-23-11706-g001.png

Figure 1. The role of cyclomodulins in carcinogenesis. CNF1, activating Rho GTPases, causes changes in the actin cytoskeleton, which leads to blocking of cytokinesis and the occurrence of aneuploidy and the epithelial-mesenchymal transition of cells. GTPases suppress the expression of cyclin B1 by arresting the cell cycle in the G2/M phase and increasing the transcription of Bcl-2 and Bcl-XL factors without triggering apoptosis. Aneuploidy, senescence, and the acquisition of a mesenchymal phenotype by cells lead to the development and progression of cancer. CIF, by binding to the ubiquitin-like protein NEDD8, inhibits the activity of CRL ubiquitin ligase. As a result, p21 and p27 accumulate in the cell, which leads to cell cycle arrest, prevention of eukaryotic cell proliferation, and delayed apoptosis. The genotoxins colibactin and CDT cause DNA damage resulting in cell cycle arrest at the G1/S and G2/M checkpoints. Cell growth and cell renewal arrest facilitate bacterial colonization. The cellular response to significant DNA damage consists either in the development of apoptosis or in the formation of a cellular senescence phenotype. Incomplete DNA repair of surviving cells leads to genomic instability, initiation of tumor development, and/or increased tumor growth. (Figure 1 was created using the images from Servier Medical Art https://smart.servier.com/ 26 June 2022).

An experimentally in vitro epithelial-mesenchymal transition of intestinal epithelial cells induced by CNF1 was established. The acquisition of a mesenchymal phenotype by cells is currently recognized as one of the decisive factors in cancer progression ^[23]. It was also evident that GTPases activated by the Rho toxin can suppress the expression of cyclin B1; as a result, tumor cells (HeLa) are blocked in the G2/M phase without triggering an apoptotic response ^[24].

Despite the supposed role of the toxin in the development and/or progression of tumors, there are also records of the antitumor effect of CNF1 on mouse and human glioma cells, which leads to the blocking of cytokinesis of proliferating tumor cells, their aging, and death ^[25]. A recombinant CTX-CNF1 toxin that can penetrate the blood–brain barrier, selectively recognizes and affects glioma cells, and was created based on CNF1 and chlorotoxin (CTX) obtained from the venom of the scorpion Leiurus quinquestriatus ^[26].

Despite the specific activity of CNF1 against Rho GTPases and their permanent activation as a result of the constitutive association of Rho GTPase with GTP, some of the Rho pathways are activated temporarily. In this case, Rho proteins are depleted as a result of their ubiquitin-mediated proteasome degradation, which depends on the cell type. Thus, in HUVEC endothelial cells, macrophages, keratinocytes, fibroblasts, and 804G epithelial cells, the level of Rho ubiquitination is high, while in HEp-2, Vero, and HEK293 cells, it is low ^[21].

3. Cyclomodulins—CIFs

CIFs belong to bacterial cyclomodulins with enzymatic activities. The injection of CIF into the eukaryotic cell is carried out by the type III secretion system (T3SS), which transports various effector proteins into the host cell. CIF contributes to changes in eukaryotic cellular pathways in favor of the pathogen by arresting the cell cycle in the G1/S and G2/M phases. Irreversible cytopathic effects of CIF were first described in enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) in an infection model on cultured HeLa cells ^[27].

CIF homologs were found in other bacteria of vertebrates (e.g., Burkholderia pseudomallei and Y. pseudotuberculosis) and invertebrates (e.g., Photorhabdus luminescens and Photorhabdus asymbiotica), and it has been shown that CIFs are conserved cyclomodulin proteins due to the presence of a conserved catalytic triad (Cys109-His165-Gln185). When the residues of this triad mutate, the cytopathic effect of CIF is not manifested ^[27]^[28].

CIF is encoded by a lambda-like prophage, and the cif gene may have spread widely through horizontal gene transfer. It is assumed that prophages encoding CIF are positively selected in bacteria to give them certain advantages in realizing their pathogenic potential. Thus, CIF in EPEC and EHEC is closely related to the LEE (locus of enterocyte effacement) pathogenicity island. CIF uses the existing T3SS, encoded by the LEE pathogenicity island, to be injected into target cells, and the resulting cytopathic effects slow down the turnover of affected cells. This gives selective advantages to LEE-positive E. coli over competing bacteria, especially in short-term adaptation processes ^[29].

Cell cycle arrest in the G2/M phase is associated with sustained CDK1 phosphorylation induced by CIF. At the same time, CIF is not a genotoxin and does not damage DNA like other cyclomodulins such as CDT or colibactin; therefore, it induces G2/M transition arrest regardless of activation of the DNA damage checkpoint pathway. CIF also blocks the entry of eukaryotic cells into the S phase, stopping the cell cycle in the G1/S phase. As a result of CIF action, CDK inhibitor proteins accumulate in cells: p21 inhibits the CDK1/CyclinB complex and the G2/M transition; p27, which, along with p21, inhibits the CDK2/CyclinE and A complexes and the G1/S transition ^[12]^[30].

Further studies have shown that the accumulation of p21 and p27 in infected cells is associated with the inactivation of CRL (Cullin-Ring ubiquitin Ligase), in which p21 and p27 are substrates of, and are degraded by, the ubiquitin-proteasome system. CIF, having deamidase enzymatic activity against NEDD8, a ubiquitin-like protein, impairs the conjugation of NEDD8 to Cullin, which leads to CRL inactivation. Thus, CIF inhibits ubiquitin-dependent degradation pathways of p21 and p27 proteins that regulate the cell cycle (Figure 1) ^[30]^[31].

The end result of inhibition of the proteasomal degradation pathway is cell cycle arrest prior to host cell destruction and apoptosis. By preventing proliferation, CIF can inhibit intestinal epithelial cell turnover, enhancing bacterial colonization. Delayed apoptosis or inhibition of apoptosis, associated, for example, with the accumulation of p21 in cells, also contributes to the local persistence of microorganisms. In addition, in an in vitro experiment, the time of death of cells exposed to CIF differed in various cell lines, which depended on the genetic background of the cells: HeLa cells died 72 h after infection; intestinal epithelial cells (IEC-6) with positive p53 died 48 h after infection ^[12]^[28].

Although, in in vitro experiments, CIF inhibited the proliferation of cancer cells and eventually led to apoptosis, where new epidemiological data confirm the role of CIF in carcinogenesis. In a recent multicenter case-control study, an association of the cif gene with precancerous lesions—intestinal polyps or adenomas—was found that can occur in the early stages of carcinogenesis, and this association has been assessed as a statistically significant risk factor ^[32].

4. Cyclomodulins—Genotoxins

Among the bacterial toxins, there is a unique group of genotoxins whose molecular target is DNA. The action of these toxins implements one of the strategies for the survival and adaptation of microorganisms to the ecological niche, aimed at causing damage to the host cells. Currently, three bacterial toxins are classified as genotoxins: polyketide toxin (colibactin), cytolethal distending toxin, and a toxin produced by S. typhi ^[33]^[34].

All eukaryotic cells respond to DNA damage and repair it, preserving the integrity of the genome. DNA breaks not eliminated during repair lead to cytogenetic disorders, oncotransformation, or cell death. Genotoxins cause single-strand or double-strand DNA breaks in target cells and trigger a signaling pathway that prevents the transition between phases of the cell cycle, resulting in its arrest, cellular senescence, or apoptosis ^[33]^[35].

Inhibition of cell proliferation and renewal by genotoxins promotes local bacterial colonization as a result of increased bacterial adhesion, which can occur due to changes in the distribution of receptors on the surface of affected cells with impaired cell morphology. Along with the cells, the functional capacity of the tissues composed of them and the local lymphocytes exposed to toxins also change, which can lead to bacterial invasion and infection ^[36]. Chronic inflammatory diseases are associated with an increased risk of developing tumors. In the case of bacterial genotoxins, there is an assumption that damaged DNA is the main factor in the acquisition of a malignant phenotype by cells and the onset and/or progression of a tumor, especially in combination with host genetic factors ^[37]. Figure 1 shows the main events that lead eukaryotic cells to develop a malignant phenotype under the influence of genotoxins.

Colibactin, a nonribosomal polyketide peptide, is a secondary metabolite found in various species of bacteria of the Enterobacteriaceae family, including E. coli, Citrobacter koseri, Klebsiella pneumoniae, and Enterobacter aerogenes, carrying the genomic island of polyketide synthase (pks) on the bacterial chromosome. The origin of pks is not entirely clear, but it has been hypothesized that the clb gene cluster spreads by horizontal transfer (HGT) through ICE-like elements (integrative and conjugative elements, ICEs) and undergoes a stabilization (homing) process upon their chromosomal integration ^[9]^[38].

The pks island was originally described in the extraintestinal pathogenic E. coli, ExPEC (Nougayrede et al., 2006) ^[39]. It has been shown that the presence of the pks island among E. coli is characteristic of the B2 phylogenetic group, which includes most of the ExPEC strains characterized by high virulence, such as expression of the K1 capsule in E. coli causing sepsis and neonatal meningitis ^[39]^[40]. The pks gene cluster in K. pneumoniae is identical to E. coli and is also associated with K. pneumoniae hypervirulence ^[41]. It is noteworthy that the systemic infection of E. coli K1 and K. pneumoniae K1 necessarily includes the invasion of the intestinal mucosa and the stage of intestinal translocation, which is reduced due to impaired colonization of the intestine by these bacteria upon inactivation of individual genes of the pks island-clbA or clbP, in experimental infections of animals ^[42]^[43]. The B2 group is associated with the carriage of many pathogenicity factors: adhesins (P- and Type 1 Fimbriae), capsular antigens (K1 and K5), aerobactin, hemolysin, and some pathogenicity islands (PAIs) associated with the persistence of E. coli in the intestinal microbiota. These factors increase the adaptability of bacteria to the normal intestinal environment, and the occurrence of extraintestinal virulence is an accidental by-product of commensalism ^[44]. The pks island is also often detected in intestinal isolates of E. coli extracted from healthy people, including infants, and is even present in the probiotic strain E. coli Nissle 1917 ^[45]. Probably, the acquisition of genotoxicity promotes increased colonization of the intestine by pks + bacteria, acting as a factor in the survival of bacteria that create and expand their own niches in the complex microbial ecosystem of the intestine ^[46]^[47]. Successful competition for host biotopes of microorganisms is also associated with their antimicrobial activity and intermediate products formed during the synthesis of colibactin, inhibiting the growth of other bacteria—Staphylococcus aureus, Bacillus subtilis—and giving an advantage to bacteria carrying pks genes ^[46]^[48].

The pks genomic island of E. coli contains 19 genes (from clbA to clbS), 54 kb in size, encoding the synthesis of colibactin, while the structure of the compound remains unknown due to its high instability. The structure of 13 synthetic derivatives of colibactin was proposed using a synthesis strategy, and it has been shown that the formation of an electrophilic cyclopropane fragment, which can bind to DNA and alkylate adenine of both strands, causing DNA interstrand cross-links, ultimately occurs. This phenomenon has been identified both in HeLa cells and in mouse models ^[49]^[50].

The genotoxic activity of colibactin depends on contact with human or animal cells and is not observed when cell lines are treated with pks + E. coli bacterial culture supernatants or their lysates. This contact is facilitated by inflammation when the mucus layer on the surface of the colon is broken, and the contact of the intestine’s surface cells with live pks + E. coli becomes possible ^[51]^[52]. Mucus becomes more permeable when mucosal homeostasis is disturbed, including excessive consumption of mucus glycans by microorganisms as an alternative source of nutrients. As a result, bacteria penetrate into the inner layers of mucus, and severe damage can lead to erosion of the colonic mucosa ^[53]. In addition, many intestinal bacteria interact with mucosal carbohydrates, glycoproteins, and glycolipids to colonize the mucosal surface. Toxin-producing bacteria may have a double advantage in intestinal colonization due to the fact that toxins also attach to host glycan structures. It is likely that the disturbed mucus layer can not only affect the pathogenic and carcinogenic potential of bacteria, but also their ability to penetrate the inner mucus layer and interact with transmembrane mucins covering the apical surface of enterocytes ^[54].

Subsequent changes in cells, once bacteria are in close contact with them, are associated with DNA double-strand breaks (DSB) accompanied by phosphorylation of replication protein A (pRPA) and histone H2AX (pH2AX), which occur due to replication stress caused by DNA cross-links. The ATM-CHK2 DNA damage checkpoint pathway is activated, and the cell cycle stops at the G2/M stage, resulting in subsequent incomplete DNA repair ^[46]. By damaging DNA and blocking the cell cycle, the renewal of eukaryotic cells is slowed down, which contributes to the stability and long-term persistence of pks + bacteria in the complex microbial communities of the host intestine ^[52]. Further events in cells damaged by colibactin can be considered as its side effect, promoting carcinogenesis. Surviving eukaryotic cells are characterized by genomic instability, expressed in chromosomal aberrations, aneuploidy, and an increase in the frequency of gene mutations ^[9]^[14]. The role of pks + E. coli in mutagenesis was confirmed by a study conducted on human intestinal organelles derived from primary crypt stem cells. In organelles exposed to pks + E. coli, mutational signatures of SBS-pks were revealed with an increased level of single base substitutions (SBS) in ATA, ATT, and TTT, with the replacement of the middle T and small indel, ID-pks, with single T deletions at homopolymers. In addition, upstream of the SBS-pks sites and upstream of the poly-T site in ID-pks, adenine enrichment was found, which is characteristic of pks signatures and distinguishes them from those of other alkylating agents. Notably, based on the analysis of WGS data from a Dutch collection of solid cancer metastases, SBS-pks and ID-pks signatures were detected mainly in CRC ^[55].

A dose-dependent effect of pks + E. coli on eukaryotic cells has been shown as follows: low doses induced a transient response to DNA damage followed by resumption of cell division with signs of damaged DNA; high doses of toxigenic bacteria caused irreversible cell cycle arrest and apoptosis ^[13]. A large number of pks + bacteria causes massive DNA damage and phenotypic cellular senescence, in which the cytotoxic effect of colibactin is observed—megalocytosis, the absence of mitosis ^[43]^[50]. Senescent cells begin to secrete pro-inflammatory cytokines, chemokines, proteases, and growth factors into the environment, such as hepatocyte growth factor (HGF), which stimulate the proliferation of uninfected neighboring cells. Therefore, pks + bacteria accelerate the progression of neoplasms, as shown in mouse models of colon tumors ^[56]^[57].

Thus, the putative role of colibactin in carcinogenesis may be associated with both the initiation of tumor development and enhancement of tumor growth. In support of this, colibactin-positive bacteria are found with increased frequency in patients with inflammatory bowel disease (IBD), familial adenomatous polyposis, and colorectal cancer (CRC) and are associated with the etiology and pathogenesis of these diseases ^[58]^[59]. Accumulating epidemiological evidence indicates the existence of dietary risk factors for colorectal cancer that are metabolized by the gut microbiota and may influence its composition. A high intake of grains or a low intake of vegetables, especially from the cruciferous family, revealed a positive association between pks + E. coli and colorectal neoplasia ^[60].

Infections of other organs by pks + bacteria are also considered to be an increased risk factor for cancer. Thus, bladder cancer may be preceded by regular urinary tract infections (UTIs) caused by E. coli pks + ^[11]. It has been shown that in the urine of patients infected with isolates of uropathogenic E. coli (UPEC) pks +, the C14-Asn metabolite, which is formed during the synthesis of colibactin, is detected, and damage by colibactin to the DNA of urothelial cells Krt14 from which a significant part of cancer tissue originates, was experimentally confirmed on rodents. ^[61].

Cytolethal distending toxin is a genotoxin produced by many Gram-negative bacteria, such as E. coli, Campylobacter spp., Aggregatibacter actinomycetemcomitans, Haemophilus ducreyi, Helicobacter spp., Shigella dysenteriae, Haemophilus spp., Providencia alcalifaciens ^[10]^[62]^[63]. CDT-producing bacteria colonize mucus membranes and skin as commensals or as agents of localized or disseminated infections in mammals ^[14]. Initially, CDT was detected in pathogenic E. coli upon treatment of Vero, CHO, HeLa, and HEp-2 eukaryotic cells with bacterial culture supernatant, which caused cell elongation and nucleus enlargement 120 h after addition ^[64].

5. Specific Microbial Metabolites

Bacterial populations in the human body and specific metabolites associated with them support physiological functions in its various biotopes. Depending on the genetic and epigenetic background of the host, an imbalance between the protective and pathological functions of microbial metabolites can lead to the occurrence of diseases, including cancer ^[15]^[65]. Figure 2 shows the main events that lead eukaryotic cells to develop a malignant phenotype when exposed to bacterial metabolites.

/media/item_content/202210/6348007e4e9f0ijms-23-11706-g002.png

Figure 2. Contribution of commensal bacteria microbial metabolites to carcinogenesis. By stimulating the proteasomal degradation of p53 and inducing cancer stem cells (CSC), secondary BAs lead to malignant transformation of cells. Oxidative damage to DNA by secondary BA and butyrate is associated with the formation of ROS, which cannot be restored in genetically modified cells, which leads to the formation of resistance to apoptosis, increased autophagy, and cancer development. Butyrate inhibits HDAC in normal and cancer cells. The action of butyrate upon HDAC3 of intestinal macrophages reduces the activity of the mTOR protein, as a result of which autophagy in macrophages is enhanced. This is how butyrate-producing bacteria maintain the optimal level of their population. By inhibiting HDAC, butyrate induces the expression of p21, which arrests the cell cycle at the G1-S stage: cells can undergo apoptosis or acquire a senescence-associated secretory phenotype leading to the development or progression of cancer. By inhibiting the production of cyclic adenosine monophosphate (cAMP), lactic acid activates autophagy in vaginal epithelial cells, protecting them from intracellular microorganisms. Protective autophagy in tumor cells prevents apoptosis, promoting tumor metastasis. By blocking HDAC, lactic acid increases the production of NGAL by epithelial cells, which inhibits the growth of other microorganisms, inducing selective transcription of genes in malignantly transformed cells, which contributes to their survival and stimulates oncogenesis. (Figure 2 was created using images from Servier Medical Art https://smart.servier.com/ 26 June 2022).

References

Van Elsland, D.; Neefjes, J. Bacterial infections and cancer. EMBO Rep. 2018, 19, e46632.
Silva-García, O.; Valdez-Alarcón, J.J.; Baizabal-Aguirre, V.M. Wnt/β-catenin signaling as a molecular target by pathogenic bacteria. Front. Immunol. 2019, 10, 2135.
Avril, M.; DePaolo, R.W. “Driver-passenger” bacteria and their metabolites in the pathogenesis of colorectal cancer. Gut Microbes 2021, 13, 1941710.
Rubinstein, M.R.; Baik, J.E.; Lagana, S.M.; Han, R.P.; Raab, W.J.; Sahoo, D.; Han, Y.W. Fusobacterium nucleatum promotes colorectal cancer by inducing Wnt/β-catenin modulator Annexin A1. EMBO Rep. 2019, 20, e47638.
El-Aouar Filho, R.A.; Nicolas, A.; De Paula Castro, T.L.; Deplanche, M.; De Carvalho Azevedo, V.A.; Goossens, P.L.; Taieb, F.; Lina, G.; Le Loir, Y.; Berkova, N. Heterogeneous Family of Cyclomodulins: Smart Weapons That Allow Bacteria to Hijack the Eukaryotic Cell Cycle and Promote Infections. Front. Cell Infect. Microbiol. 2017, 23, 208.
Bhavsar, A.P.; Guttman, J.A.; Finlay, B.B. Manipulation of host-cell pathways by bacterial pathogens. Nature 2007, 449, 827–834.
Rosadi, F.; Fiorentini, C.; Fabbri, A. Bacterial protein toxins in human cancers. Pathog. Dis. 2016, 74, ftv105.
Mezerová, K.; Starý, L.; Zbořil, P.; Klementa, I.; Stašek, M.; Špička, P.; Skalický, P.; Raclavský, V. Cyclomodulins and Hemolysis in E. coli as Potential Low-Cost Non-Invasive Biomarkers for Colorectal Cancer Screening. Life 2021, 11, 1165.
Bossuet-Greif, N.; Vignard, J.; Taieb, F.; Mirey, G.; Dubois, D.; Petit, C.; Nougayrède, J.P. The colibactin genotoxin generates DNA interstrand cross-links in infected cells. mBio 2018, 9, e02393-17.
Guerra, L.; Cortes-Bratti, X.; Guidi, R.; Frisan, T. The biology of the cytolethal distending toxins. Toxins 2011, 3, 172–190.
Zhang, Z.; Aung, K.M.; Uhlin, B.E.; Wai, S.N. Reversible senescence of human colon cancer cells after blockage of mitosis/cytokinesis caused by the CNF1 cyclomodulin from Escherichia coli. Sci. Rep. 2018, 8, 17780.
Samba-Louaka, A.; Nougayrède, J.P.; Watrin, C.; Jubelin, G.; Oswald, E.; Taieb, F. Bacterial cyclomodulin Cif blocks the host cell cycle by stabilizing the cyclin-dependent kinase inhibitors p21 and p27. Cell Microbiol. 2008, 10, 2496–2508.
Barrett, M.; Hand, C.K.; Shanahan, F.; Murphy, T.; O’Toole, P.W. Mutagenesis by microbe: The role of the microbiota in shaping the cancer genome. Trends Cancer 2020, 6, 277–287.
Cuevas-Ramos, G.; Petit, C.R.; Marcq, I.; Boury, M.; Oswald, E.; Nougayrède, J.P. Escherichia coli induces DNA damage in vivo and triggers genomic instability in mammalian cells. Proc. Natl. Acad. Sci. USA 2010, 107, 11537–11542.
Louis, P.; Hold, G.L.; Flint, H.J. The gut microbiota, bacterial metabolites and colorectal cancer. Nat. Rev. Microbiol. 2014, 12, 661–672.
Chaoprasid, P.; Lukat, P.; Mühlen, S.; Heidler, T.; Gazdag, E.M.; Dong, S.; Blankenfeldt, W. Crystal structure of bacterial cytotoxic necrotizing factor CNFY reveals molecular building blocks for intoxication. EMBO J. 2021, 40, e105202.
Ho, M.; Mettouchi, A.; Wilson, B.A.; Lemichez, E. CNF1-like deamidase domains: Common Lego bricks among cancer-promoting immunomodulatory bacterial virulence factors. Pathog. Dis. 2018, 76, fty045.
Fabbri, A.; Travaglione, S.; Ballan, G.; Loizzo, S.; Fiorentini, C. The cytotoxic necrotizing factor 1 from E. coli: A janus toxin playing with cancer regulators. Toxins 2013, 5, 1462–1474.
Aktories, K. Bacterial protein toxins that modify host regulatory GTPases. Nat. Rev. Microbiol. 2011, 9, 487–498.
Garcia, T.A.; Ventura, C.L.; Smith, M.A.; Merrell, D.S.; O’Brien, A.D. Cytotoxic necrotizing factor 1 and hemolysin from uropathogenic Escherichia coli elicit different host responses in the murine bladder. Infect. Immun. 2013, 81, 99–109.
Carlini, F.; Maroccia, Z.; Fiorentini, C.; Travaglione, S.; Fabbri, A. Effects of the Escherichia coli Bacterial Toxin Cytotoxic Necrotizing Factor 1 on Different Human and Animal Cells: A Systematic Review. Int. J. Mol. Sci. 2021, 22, 12610.
Falzano, L.; Filippini, P.; Travaglione, S.; Miraglia, A.G.; Fabbri, A.; Fiorentini, C. Escherichia coli cytotoxic necrotizing factor 1 blocks cell cycle G2/M transition in uroepithelial cells. Infect. Immun. 2006, 74, 3765–3772.
Fabbri, A.; Travaglione, S.; Rosadi, F.; Ballan, G.; Maroccia, Z.; Giambenedetti, M.; Fiorentini, C. The Escherichia coli protein toxin cytotoxic necrotizing factor 1 induces epithelial mesenchymal transition. Cell. Microbiol. 2020, 22, e13138.
De Rycke, J.E.A.N.; Mazars, P.; Nougayrede, J.P.; Tasca, C.; Boury, M.; Herault, F.; Oswald, E. Mitotic block and delayed lethality in HeLa epithelial cells exposed to Escherichia coli BM2-1 producing cytotoxic necrotizing factor type 1. Infect. Immun. 1996, 64, 1694–1705.
Tantillo, E.; Colistra, A.; Vannini, E.; Cerri, C.; Pancrazi, L.; Baroncelli, L.; Caleo, M. Bacterial toxins and targeted brain therapy: New insights from cytotoxic necrotizing factor 1 (CNF1). Int. J. Mol. Sci. 2018, 19, 1632.
Vannini, E.; Mori, E.; Tantillo, E.; Schmidt, G.; Caleo, M.; Costa, M. CTX-CNF1 Recombinant Protein Selectively Targets Glioma Cells In Vivo. Toxins 2021, 13, 194.
Jubelin, G.; Chavez, C.V.; Taieb, F.; Banfield, M.J.; Samba-Louaka, A.; Nobe, R.; Nougayrède, J.P.; Zumbihl, R.; Givaudan, A.; Escoubas, J.M.; et al. Cycle inhibiting factors (CIFs) are a growing family of functional cyclomodulins present in invertebrate and mammal bacterial pathogens. PLoS ONE 2009, 4, e4855.
Samba-Louaka, A.; Nougayrède, J.P.; Watrin, C.; Oswald, E.; Taieb, F. The enteropathogenic Escherichia coli effector Cif induces delayed apoptosis in epithelial cells. Infect. Immun. 2009, 77, 5471–5477.
Loukiadis, E.; Nobe, R.; Herold, S.; Tramuta, C.; Ogura, Y.; Ooka, T.; Morabito, S.; Kérourédan, M.; Brugère, H.; Schmidt, H.; et al. Distribution, functional expression, and genetic organization of Cif, a phage-encoded type III-secreted effector from enteropathogenic and enterohemorrhagic Escherichia coli. J. Bacteriol. 2008, 190, 275–285.
Taieb, F.; Nougayrède, J.P.; Oswald, E. Cycle inhibiting factors (cifs): Cyclomodulins that usurp the ubiquitin-dependent degradation pathway of host cells. Toxins 2011, 3, 356–368.
Cui, J.; Yao, Q.; Li, S.; Ding, X.; Lu, Q.; Mao, H.; Liu, L.; Zheng, N.; Chen, S.; Shao, F. Glutamine deamidation and dysfunction of Ubiquitin/NEDD8 by a bacterial effector family. Science 2010, 329, 1215–1218.
Piciocchi, A.; Germinario, E.A.P.; Garcia Etxebarria, K.; Rossi, S.; Sanchez-Mete, L.; Porowska, B.; Stigliano, V.; Trentino, P.; Oddi, A.; Accarpio, F.; et al. Association of Polygenic Risk Score and Bacterial Toxins at Screening Colonoscopy with Colorectal Cancer Progression: A Multicenter Case-Control Study. Toxins 2021, 13, 569.
Martin, O.C.B.; Frisan, T. Bacterial Genotoxin-Induced DNA Damage and Modulation of the Host Immune Microenvironment. Toxins 2020, 12, 63.
Pokkunuri, V.; Pimentel, M.; Morales, W.; Jee, S.R.; Alpern, J.; Weitsman, S.; Chang, C. Role of cytolethal distending toxin in altered stool form and bowel phenotypes in a rat model of post-infectious irritable bowel syndrome. Neurogastroenterol. Motil. 2012, 18, 434.
Grasso, F.; Frisan, T. Bacterial genotoxins: Merging the DNA damage response into infection biology. Biomolecules 2015, 5, 1762–1782.
De Rycke, J.; Oswald, E. Cytolethal distending toxin (CDT): A bacterial weapon to control host cell proliferation? FEMS Microbiol. Lett. 2001, 203, 141–148.
Lai, Y.R.; Chang, Y.F.; Ma, J.; Chiu, C.H.; Kuo, M.L.; Lai, C.H. From DNA Damage to Cancer Progression: Potential Effects of Cytolethal Distending Toxin. Front. Immunol. 2021, 12, 760451.
Wami, H.; Wallenstein, A.; Sauer, D.; Stoll, M.; von Bünau, R.; Oswald, E.; Dobrindt, U. Insights into evolution and coexistence of the colibactin-and yersiniabactin secondary metabolite determinants in enterobacterial populations. Microb. Genom. 2021, 7, 000577.
Nougayrède, J.P.; Homburg, S.; Taieb, F.; Boury, M.; Brzuszkiewicz, E.; Gottschalk, G.; Oswald, E. Escherichia coli induces DNA double-strand breaks in eukaryotic cells. Science 2006, 313, 848–851.
Johnson, J.R.; Johnston, B.; Kuskowski, M.A.; Nougayrede, J.P.; Oswald, E. Molecular epidemiology and phylogenetic distribution of the Escherichia coli pks genomic island. J. Clin. Microbiol. 2008, 46, 3906–3911.
Strakova, N.; Korena, K.; Karpiskova, R. Klebsiella pneumoniae producing bacterial toxin colibactin as a risk of colorectal cancer development-systematic review. Toxicon 2021, 197, 126–135.
McCarthy, A.J.; Martin, P.; Cloup, E.; Stabler, R.A.; Oswald, E.; Taylor, P.W. The genotoxin colibactin is a determinant of virulence in Escherichia coli K1 experimental neonatal systemic infection. Infect. Immun. 2015, 83, 3704–3711.
Lu, M.C.; Chen, Y.T.; Chiang, M.K.; Wang, Y.C.; Hsiao, P.Y.; Huang, Y.J.; Lai, Y.C. Colibactin contributes to the hypervirulence of pks+ K1 CC23 Klebsiella pneumoniae in mouse meningitis infections. Front. Cell. Infect. Microbiol. 2017, 7, 103.
Le Gall, T.; Clermont, O.; Gouriou, S.; Picard, B.; Nassif, X.; Denamur, E.; Tenaillon, O. Extraintestinal virulence is a coincidental by-product of commensalism in B2 phylogenetic group Escherichia coli strains. Mol. Biol. Evol. 2007, 24, 2373–2384.
Nougayrède, J.P.; Chagneau, C.V.; Motta, J.P.; Bossuet-Greif, N.; Belloy, M.; Taieb, F.; Gratadoux, J.J.; Thomas, M.; Langella, P.; Oswald, E.A. Toxic Friend: Genotoxic and Mutagenic Activity of the Probiotic Strain Escherichia coli Nissle 1917. mSphere 2021, 6, e0062421.
Faïs, T.; Delmas, J.; Barnich, N.; Bonnet, R.; Dalmasso, G. Colibactin: More than a new bacterial toxin. Toxins 2018, 10, 151.
Tronnet, S.; Floch, P.; Lucarelli, L.; Gaillard, D.; Martin, P.; Serino, M.; Oswald, E. The genotoxin colibactin shapes gut microbiota in mice. mSphere 2020, 5, e00589-20.
Faïs, T.; Cougnoux, A.; Dalmasso, G.; Laurent, F.; Delmas, J.; Bonnet, R. Antibiotic activity of Escherichia coli against multiresistant Staphylococcus aureus. Antimicrob. Agents Chemother. 2016, 60, 6986–6988.
Wilson, M.R.; Jiang, Y.; Villalta, P.W.; Stornetta, A.; Boudreau, P.D.; Carrá, A.; Balskus, E.P. The human gut bacterial genotoxin colibactin alkylates DNA. Science 2019, 363, eaar7785.
Kurnick, S.A.; Mannion, A.J.; Feng, Y.; Madden, C.M.; Chamberlain, P.; Fox, J.G. Genotoxic Escherichia coli strains encoding Colibactin, Cytolethal Distending Toxin, and Cytotoxic necrotizing factor in laboratory rats. Comp. Med. 2019, 69, 103–113.
Arthur, J.C.; Perez-Chanona, E.; Muhlbauer, M.; Tomkovich, S.; Uronis, J.M.; Fan, T.J.; Campbell, B.J.; Abujamel, T.; Dogan, B.; Rogers, A.B.; et al. Intestinal inflammation targets cancer-inducing activity of the microbiota. Science 2012, 338, 120–123.
Reuter, C.; Alzheimer, M.; Walles, H.; Oelschlaeger, T.A. An adherent mucus layer attenuates the genotoxic effect of colibactin. Cell. Microbiol. 2018, 20, e12812.
Melhem, H.; Regan-Komito, D.; Niess, J.H. Mucins Dynamics in Physiological and Pathological Conditions. Int. J. Mol. Sci. 2021, 22, 13642.
Josenhans, C.; Müthing, J.; Elling, L.; Bartfeld, S.; Schmidt, H. How bacterial pathogens of the gastrointestinal tract use the mucosal glyco-code to harness mucus and microbiota: New ways to study an ancient bag of tricks. Int. J. Med. Microbiol. 2020, 310, 151392.
Pleguezuelos-Manzano, C.; Puschhof, J.; Rosendahl Huber, A.; van Hoeck, A.; Wood, H.M.; Nomburg, J.; Gurjao, C.; Manders, F.; Dalmasso, G.; Stege, P.B.; et al. Mutational signature in colorectal cancer caused by genotoxic pks+ E. coli. Nature 2020, 580, 269–273.
Gagnière, V.; Bonnin, A.S.; Jarrousse, E.; Cardamone, A.; Agus, N.; Uhrhammer, P.; Sauvanet, P.; Déchelotte, N.; Barnich, R.; Bonnet, D.; et al. Bonnet Interactions between microsatellite instability and human gut colonization by Escherichia coli in colorectal cancer. Clin. Sci. 2017, 131, 471–485.
Taieb, F.; Petit, C.; Nougayrede, J.P.; Oswald, E. The Enterobacterial Genotoxins: Cytolethal Distending Toxin and Colibactin. EcoSal Plus 2016, 7(1), 21.
Iyadorai, T.; Mariappan, V.; Vellasamy, K.M.; Wanyiri, J.W.; Roslani, A.C.; Lee, G.K.; Vadivelu, J. Prevalence and association of pks+ Escherichia coli with colorectal cancer in patients at the University Malaya Medical Centre, Malaysia. PLoS ONE 2020, 15, e0228217.
Bonnet, M.; Buc, E.; Sauvanet, P.; Darcha, C.; Dubois, D.; Pereira, B.; Darfeuille-Michaud, A. Colonization of the human gut by E. coli and colorectal cancer risk. Clin. Cancer Res. 2014, 20, 859–867.
Iwasaki, M.; Kanehara, R.; Yamaji, T.; Katagiri, R.; Mutoh, M.; Tsunematsu, Y.; Sato, M.; Watanabe, K.; Hosomi, K.; Kakugawa, Y.; et al. Association of Escherichia coli containing polyketide synthase in the gut microbiota with colorectal neoplasia in Japan. Cancer Sci. 2022, 113, 277–286.
Vermeulen, S.H.; Hanum, N.; Grotenhuis, A.J.; Castano-Vinyals, G.; Van Der Heijden, A.G.; Aben, K.K.; Kiemeney, L.A. Recurrent urinary tract infection and risk of bladder cancer in the Nijmegen bladder cancer study. Br. J. Cancer 2015, 112, 594–600.
Faïs, T.; Delmas, J.; Serres, A.; Bonnet, R.; Dalmasso, G. Impact of CDT Toxin on Human Diseases. Toxins 2016, 8, 220.
Azzi-Martin, L.; He, W.; Péré-Védrenne, C.; Korolik, V.; Alix, C.; Prochazkova-Carlotti, M.; Morel, J.L.; Le Roux-Goglin, E.; Lehours, P.; Djavaheri-Mergny, M.; et al. Cytolethal distending toxin induces the formation of transient messenger-rich ribonucleoprotein nuclear invaginations in surviving cells. PLoS Pathog. 2019, 15, e1007921.
Johnson, W.M.; Lior, H. Response of Chinese hamster ovary cells to a cytolethal distending toxin (CDT) of Escherichia coli and possible misinterpretation as heat-labile (LT) enterotoxin. FEMS Microbiol. Lett. 1987, 43, 19–23.
Tarashi, S.; Siadat, S.D.; Ahmadi Badi, S.; Zali, M.; Biassoni, R.; Ponzoni, M.; Moshiri, A. Gut Bacteria and their Metabolites: Which One Is the Defendant for Colorectal Cancer? Microorganisms 2019, 7, 561.

© Text is available under the terms and conditions of the Creative Commons Attribution (CC BY) license; additional terms may apply. By using this site, you agree to the Terms and Conditions and Privacy Policy.

Upload a video for this entry

Information

Subjects: Microbiology

Contributors MDPI registered users' name will be linked to their SciProfiles pages. To register with us, please refer to https://encyclopedia.pub/register :

View Times: 583

Update Date: 13 Oct 2022

Table of Contents

Video Upload Options

Confirm