| Objective:Microbiota is potentially involved in the pathogenesis of gastrointestinal cancer.However,the profile of microbiota in cancerous tissue and noncancerous tissue of gastric cancer remains unclear.This study was aimed to perform a comparative analysis of the characteristics of microbiota in gastric cancer by comparing mucosal microbiota of neoplastic lesions to microbiota of adjacent gastric mucosa.Methods:A total of 88 patients with gastric cancer were enrolled in the study.Two samples were collected from neoplastic lesions and adjacent gastric mucosa from each patient,respectively.Neoplastic tissues were obtained from cancerous lesions,while paraneoplastic tissues were taken from normal mucosa at the removal edges.One tissue sample was processed for routine histological examination.The other one was stored at-80? for DNA extraction.The bacterial localization was determined using fluorescence in situ hybridization.The bacterial amounts and abundance of Fusobacterium in gastric mucosa were analyzed using real-time quantitative PCR(qPCR).Molecular analyses of microbiota in neoplastic tissues and paraneoplastic tissues from six patients were conducted.Results:(1)The bacteria were mainly located in the mucus layer of stomach.The distribution pattern of mucosal microbiota was similar among neoplastic tissues and paraneoplastic tissues.(2)The number of bacteria in neoplastic lesions was estimated to be 7.89 ± 0.88(log),while it was 8.13 ± 0.89(log)in adjacent gastric mucosa.But they had not reached the significant difference.(3)Chao1 index of mucosal microbiota was estimated to be 880 ± 192 in cancerous tissues,which was not significantly different to that of non-cancerous tissues(P>0.05).(4)Molecular analyses of microbiota in neoplastic tissues showed the Shannon index was 2.31 ± 0.73.It was slightly higher than that of microbiota in paraneoplastic tissues,but they had not reached the significant difference(P > 0.05).(5)NMDS analyses showed a scattered pattern of neoplastic and paraneoplastic samples.There was no obvious segregation of neoplastic samples.(6)Using the DMM-based approach,we identified 3 community types a,b,c in gastric microbiota according to the number of Dirichlet mixture components K.The community type was generally consistent between paired neoplastic tissues and paraneoplastic tissues within same individual.(7)The abundances of Fusobacterium,Moryella and Porphyromonas in neoplastic tissues were significantly increased(all P < 0.05).Fusobacterium in neoplastic tissues was further confirmed to be enriched by qPCR analyses.Conclusion:The study found the profile of microbiota in cancerous tissue was remarkably similar to that of paracancerous tissue.But enrichment of three genera was found in cancerous tissue,which may contribute to the carcinogenesis of stomach.Their role in gastric carcinogenesis remains further investigations. |
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