Microbial characterization of esophageal squamous cell carcinoma and gastric cardia adenocarcinoma from a high-risk region of China

Abstract

Background: Little is known about the microbiota and upper gastrointestinal tumors. Esophageal squamous cell carcinoma (ESCC) and gastric cardia adenocarcinoma (GCA) occur in adjacent organs, co-occur geographically, and share many risk factors despite being of different tissue types.

Methods: This study characterized the microbial communities of paired tumor and nontumor samples from 67 patients with ESCC and 36 patients with GCA in Henan, China. DNA was extracted with the MoBio PowerSoil kit. The V4 region of the 16S ribosomal RNA gene was sequenced with MiniSeq and was processed with Quantitative Insights Into Microbial Ecology 1. The linear discriminant analysis effect size method was used to identify differentially abundant microbes, the Wilcoxon rank-sum test was used to test α diversity differences, and permutational multivariate analysis of variance was used to test for differences in β diversity.

Results: The microbial environments of ESCC and GCA tissues were all composed primarily of Firmicutes, Bacteroidetes, and Proteobacteria. ESCC tumor tissues contained more Fusobacterium (3.2% vs 1.3%) and less Streptococcus (12.0% vs 30.2%) than nontumor tissues. GCA nontumor tissues had a greater abundance of Helicobacter (60.5% vs 11.8%), which may have been linked to the lower α diversity (58.0 vs 102.5; P = .0012) in comparison with tumor tissues. A comparison of ESCC and GCA nontumor tissues showed that the microbial composition (P = .0040) and the α diversity (87.0 vs 58.0; P = .00052) were significantly different. No significant differences were detected for α diversity within ESCC and GCA tumor tissues.

Conclusions: This study showed differences in the microbial compositions of paired ESCC and GCA tumor and nontumor tissues and differences by organ site. Large-scale, prospective cohort studies are needed to confirm these findings.

Keywords: 16S ribosomal RNA (rRNA) gene sequencing; diversity; esophageal squamous cell carcinoma; gastric cardia adenocarcinoma; microbiota.

Figure 1.

Diagram of study enrollment and eligible paired and total samples.

Figure 2.. Microbial comparison between ESCC and GCA patients for alpha diversity.

Alpha diversity of 52 paired ESCC tumor and non-tumor tissues, 24 paired GCA tumor and non-tumor tissues, 55 ESCC and 32 GCA unpaired tumor tissues, 58 ESCC and 26 GCA unpaired non-tumor tissues assessed using the Shannon index (a) and observed OTUs (b).

Figure 3.. Microbial comparison between paired tumor and non-tumor tissues from ESCC and GCA patients for beta diversity.

Comparison of beta diversity based on weighted Unifrac distance using a PCoA plot of 52 paired tumor and non-tumor tissues in ESCC patients (a), and of 24 paired tumor and non-tumor tissues in GCA patients (b).

Figure 4.. Microbial relative abundances at the phylum and genus level for ESCC and GCA patients.

Microbial relative abundance from 55 ESCC tumor tissues, 58 ESCC non-tumor tissues, 32 GCA tumor tissues and 26 GCA non-tumor tissues at the phylum and genus level. *[Prevotella] indicates unclassified genus similar to Prevotella.

Figure 5.. Comparison of the microbial communities of unpaired ESCC and GCA tissues.

Comparison of beta diversity based on weighted Unifrac distance of 55 ESCC and 32 GCA unpaired tumor tissues using a PCoA plot (a), and of 58 ESCC and 26 GCA unpaired non-tumor tissues (b).