Taxonomic and Functional Differences in Cervical Microbiome Associated with Cervical Cancer Development

Abstract

The cervical microbiome is associated with cervical cancer risk, but how microbial diversity and functional profiles change in cervical cancer remains unclear. Herein, we investigated microbialcompositional and functional differences between a control group and a high-grade cervical intraepithelial neoplasia and cervical cancer (CIN2/3-CC) group. After retrospective collection of 92 cervical swab samples, we carried out 16S rRNA amplicon sequencing on 50 and 42 samples from the control and CIN2/3-CC groups, respectively. The EzBioCloud pipeline was applied to identify the genomic features associated with the groups using 16S rRNA data. A linear discriminant analysis effect size (LEfSe) was performed to assess the enrichment in the assigned taxonomic and functional profiles. We found a lower richness in the control group relative to the CIN2/3-CC group; however, the β-diversity tended to be similar between the groups. The LEfSe analysis showed that a phylum Sacchaaribacteria_TM7, 11 genera, and 21 species were more abundant in the CIN2/3-CC group and that one uncharacterized Gardnerella species was more abundant only in the control group. Further characterization of the functional pathways using EzBioCloud showed that the 4 KEGG orthologs (Phosphotransferase system [PTS] sucrose-specific IIA, IIB, IIC components and PTS cellubiose-specific IIC component) were involved in the KEGG pathway of starch and sucrose metabolism. The two pathways of folate biosynthesis and oxidative phosphorylation were more abundant in the CIN2/3-CC group. Further confirmation of these results in larger samples can help to elucidate the potential association between the cervical microbiome and cervical cancer. Cervical intraepithelial neoplasia (CIN) is a precancerous lesion in cervical epithelial cells, and is histologically divided into different grades 1. Infection with HPV is the most important causative factor for CIN or cervical cancer. Although HPV is a major risk factor for cervical precancerous lesions or cancer, the potential role of the cervicovaginal microbiome in cervical cancer via the elevation of pH also has been reported 2. In fact, the role of the cervicovaginal microbiome in HPV infection has already been established, which fact suggests a possible role in cervical cancer through potentiation of HPV infection 3. Interestingly, the action of the microbiota is a complex process, the scientific data on which remains sparse 4,5. The impact of the microbiome and its functions on cervical pathophysiology differ among individuals 6. There is increasing evidence that the cervical microbiome plays important roles in the carcinogenesis process of the uterine cervix; thus, it is being considered as a target for development of innovative therapeutic approaches 7,8. The cervical microbiome's importance lies in its provision of the metabolic pathways and enzymatic machinery that help to process essential vitamins, remove toxic compounds, defend against pathogens, strengthen the female genital-tract epithelium, and stimulate as well a...

Predictive functional analysis reveals inferred features unique to cervicovaginal microbiota of African women with bacterial vaginosis and high-risk human papillomavirus infection

“…We compared the relative abundances of the predicted metagenome functions of CVM in CST-3 and CST-8, and CVM of women with and without BV and HR-HPV infection. Several differences in inferred KEGG functional categories that have been previously identified in cervicovaginal and uterine microbiota [ 21 , 23 – 25 ], were found in all three comparisons; thus, suggesting a connection between CVM, BV, and HR-HPV-infection. Interestingly, a majority of the predicted functional categories including, but not limited to, sporulation, bacterial motility proteins, flagellar assembly, peroxisome, and ion channels, were consistent with those observed among Taiwanese women with and without BV as diagnosed by both Amsel’s criteria and Nugent scoring [ 21 ].…”

“…Moreover, the observed clear separation of the inferred functional categories on PCoA according to BV status is analogous to the Taiwanese study, only in the case where the investigators diagnosed BV using the Nugent scoring system [ 21 ]. Functional diversity has been observed in CVM [ 25 ]. Some of the inferred functional modules (e.g., energy metabolism, DNA repair, and cell envelope biogenesis) have been underscored in the pangenome of L .…”

“…Some of these changes, for example, proteomic signatures associated with highly diverse Gardnerella vaginalis-dominated CVM, can consequently alter the cervicovaginal epithelial barrier [18], thereby decreasing its limit to infections. Approaches that have been utilized to estimate the functional and metabolic contents of microbiota include metagenomics [11,20,[23][24][25], metaproteomics [18], and computational analysis, e.g., phylogenetic investigation of communities by reconstruction of unobserved states (PICRUSt) [26] and Tax4Fun [27] using 16S rRNA marker gene sequences and databases such as Kyoto Encyclopedia of Genes and Genomes (KEGG) and Cluster of Orthologous Groups (COG).…”

Dysbiosis of the endometrial microbiota and its association with inflammatory cytokines in endometrial cancer

“…Micrococcus species are part of the normal flora of the human skin. Emerging studies in humans have linked the increased abundance of Micrococcus to cancers, such as cervical cancer, 44 colorectal cancer, 45 and tongue tumor 46 . The mechanisms that contribute to dysbiosis and alterations in microbial richness are not well understood.…”

Microbes in Tumoral In Situ Tissues and in Tumorigenesis

“…The bacterial differences of diversity between cancerous and noncancerous tissues had been discovered. Tango et al discovered that nine genera and 21 species were significantly more abundant in cervical cancer group compared to the controls (Tango et al, 2020). Audirac-Chalifour et al selected 32 cases containing 20 non-cervical lesions (NCL: 10 HPV-negative; 10 HPV-positive), four squamous intraepithelial lesions (SILs: all HPV-positive), and eight cervical cancer lesions (CCL: all HPV-positive) to analyze the alpha-diversity and the b-diversity in each group.…”