Related Oral Microbiome Research In Salivary Adenoid Cystic Carcinoma

Salivary adenoid cystic carcinoma (SACC) is a common epithelial malignancies which occurred in salivary glands, accounting for 11% of oral and maxillofacial malignancies. Salivary adenoid cystic carcinoma is generally slow-growing with the characteristics of perineural invasion and lung metastasis. The accumulation of pulmonary metastasis rate after 5 years and 10 years of post surgery is 70% and 100%, respectively. Clinically, the difficulty to determine the definite scope of infiltration, the unsatisfactory results of surgery, radiotherapy and chemotherapy, as well as the high recurrence rate significantly affect the patients’ mental and psychological quality of life. Therefore, it is key to understand the etiology and pathogenesis of SACC in depth, and try to achieve early detection, early diagnosis and early treatment.The oral cavity is a complex environment and more than 1000 bacterial species are identified. Through 16S rDNA sequencing, it is expected that the bacterial species may reach up to 25000. Studies assumed that the onset and development of tumor is related to the bacteria which affect the metabolism of the body. So far, studies of saliva tests have found the microbial population diversity associated with pancreatic cancer, stomach cancer, oral squamous cell carcinoma and atherosclerosis, which promotes the occurrence of cancer development accompanied by the changing structure of the oral microbial groups. However, the relationship between SACC and oral microorganisms has no report. The present study intended to use Miseq high-throughput sequencing technology to explore the diversity of microorganisms in saliva and dental plaque, and to identify tumor-associated microorganisms, providing a scientific basis for early diagnosis and prognosis.Methods 13 salivary adenoid cystic carcinoma patients and 10 healthy control subjects (selected the crowd age class is similar in patients with SACC) were enrolled and assigned into two groups. Their saliva and plaque were collected to analyze the diversity of microorganisms by using the high-flux 16S rDNA sequencing technology. The microbial structure differences between two groups were also compared and calculated.Results (1) In total,797342 sequence from 23 saliva samples and 18 dental plaque samples were detected, of which 706748 were high-quality sequence, with the average length of 443 bp; (2) the average number of OUT per sample was more than 300, attributed to 16 phylum,26 classes, 45 orders,71 families,135 genus; the microbial diversity of saliva and plaque in SACC group was less than that in healthy control;(3) saliva group: there are significant differences on 18 genus betweeen SACC group and the healthy control group(p<0.05),7 genus detection in SACC is higher than the healthy controls, while 11 genus is lower than the controls, the differential genus are Streptococcus, Neisseria, Prevotella, Leptotrichia, Veillonella, Fusobacterium, Gemella, Actinomyces, Capnocytophaga, Porphyromonas, Lachnoanaerobaculum, Candidate_division_TM7_norank, Rothia, Moraxella, Campylobacter, Alloprevotella, Granulicatella, Lautropia; (4) plaque group:there are significant differences on 21 genus in SACC group and the healthy control group(p<0.05),5 genus detection in SACC is higher than the healthy controls, while 16 genus is lower than the controls, the differential genus are Streptococcus, Neisseria, Prevotella, Leptotrichia, Veillonella, Fusobacterium, Actinomyces, Capnocytophaga, Gemella,Campylobacter, Porphyromonas, Alloprevotella, Granulicatella, Rothia,Corynebacterium, Lachnoanaerobaculum, Moraxella, Tannerella, Aggregatibacter, Candidate_division_TM7_norank; (5) PCoA analysis showed that:in the SACC group and the control group, in the two different environments of oral saliva and dental plaque, the composition of microorganisms concentrated in two different regions, there may be a large difference; (6) In the plaue group, we found that the detection of Veillonella is significantly lower than controls; in the saliva group, the detection of Streptococcus is significantly higher than controls.Conclusions (1) This experiment preliminary identified the microbial diversity of both saliva and plaque in SACC group were lower than controls; (2) Several genus were detected to be related to the onset and development of SACC, having significance to identify the markers of SACC which require further investigation.