Microbial overlap in dental plaque and tumor tissue of esophageal cancer patients: A pilot study

Abstract

Introduction: Microbial dysbiosis has been shown to be involved in various types of gastrointestinal cancers, but there is a dearth of strong studies linking the oral microbiome imbalance with esophageal cancer (EC).

Objectives: The main objective of the study was to identify the link between oral microbiome and EC.

Materials and methods: Twelve suspected EC and two healthy control patients were recruited. After the histological confirmation of EC, four confirmed EC patient samples and two healthy control samples were subjected to 16S metagenomics study using the Oxford Nanopore Technology sequencing platform.

Results: Species richness of microbial community was higher in the healthy controls followed by diseased plaque, tumor tissue and adjacent tissue. Bacillota, Pseudomonata, Fusobacteriota, Bacteroidota, and Campylobacterota were the major phyla identified in all the groups. Majorly prevalent genera (core microbiome analysis) in all the groups were Streptococcus, Salmonella, Bacillus, Enterococcus, Veillonella, Klebsiella, Clostridioides, Prevotella, Gemella, Selenomonas, Firmicutes, and Proteobacteria followed by Bacteroidetes and Fusobacteria.

Conclusion: Our study suggests an association between oral microbiome and EC. The prevalence of same microbial genus in the oral cavity (dental plaque) and tumor tissue depicts a possible link. Our study opens the plausible microbe-based biomarker screening of EC.

Keywords: Biomarker; dental deposits; dysbiosis; high-throughput DNA sequencing; metagenomics; microbiome.

Figure 1

Flowchart of sample processing and bioinformatics analysis of 16S metagenomics data. PCR: Polymerase chain reaction, ONT: Oxford Nanopore Technologies

Figure 2

Comparison of oral microbial community between plaque (p) and tumor tissue (t) samples. (a) Box plot showing alpha diversity differences between P and T groups at P = 0.19; (b) relative abundances at phylum level where the Y-axis signifies sample groups and X-axis represents the percent relative abundance values. For optimum taxa resolution, small taxa with counts <10 were merged; (c) relative abundances at genus level where the Y-axis signifies sample groups and X-axis represents the percent relative abundance values. For optimum taxa resolution, small taxa with counts <10 were merged. ACE: Abundance-based coverage estimator

Figure 3

Correlation analysis of microbiome at species level. Correlation threshold was set from −1 to +1 for negative and positive correlation, respectively (a); network analysis (threshold 0.5 for phylum and 0.8 for genera) at the phylum level (b); genus level (c) among P and T groups

Figure 4

Comparison of oral microbial community between P, T, AT, TH, and PH groups. (a) Box plot showing alpha diversity differences among P, T, AT, TH, and PH groups at P = 0.003; b) relative abundances at phylum level where the Y-axis signifies sample groups and X-axis represents the percent relative abundance values. For optimum taxa resolution, small taxa with counts < 10 were merged; (c) relative abundances at genus level where the Y-axis signifies sample groups and X-axis represents the percent relative abundance values. For optimum taxa resolution, small taxa with counts <10 were merged

Figure 5

Correlation analysis of microbiome at species level. Correlation threshold was set from −1 to +1 for negative and positive correlation, respectively (a); network analysis (threshold 0.5 for phylum and 0.8 for genera) at the phylum level (b); genus level (c) among P, T, AT, TH, and PH groups