Kolorektal Kanserli Hastaların Dışkı ve Tükrük Örneklerinde Mikrobiyota Analizi

Project no. 22754 · Status: Kapanmış (Yayın bekleniyor) · 2021

Summary

Colorectal cancer is one of the most common cancers in the world, its incidence is increasing in the population, and it constitutes an important part of cancer-related mortality. Despite advances in treatment, colorectal cancers are the third most common cause of death among cancers due to delayed diagnosis. The microbiota of cancer patients differs from that of healthy people, and there may be many reasons for this difference. Alterations in the microbiota and genome can be used as a biomarker in the early diagnosis of cancer, in the follow-up of prognosis, as well as a treatment target. For this purpose, studies investigating the stool microbiota in patients with colorectal cancer were conducted. However, recent studies have shown that the oral microbiota is also related to many systems in the body, and many components in the blood, such as DNA, RNA, and protein, are also found in saliva. Evidence suggests a close correlation between some microbial strains and CRC, which microbiota influences CRC development through virulence factors of pathogenic bacterial strains. In various in vivo and in vitro models, enrichment of specific bacterial species has been found to develop changes in the tumor microenvironment and promote CRC tumor formation with various molecular events. These specific microbial strains associated with CRC promise in the development of diagnostic or therapeutic biomarkers. For this purpose, 50 colorectal cancer patients (CRC) and 50 healthy controls (HC) were included in our study. Microbiota was investigated by 16S rRNA sequence analysis in 10 CRC patients and 10 HC samples. The presence of these microorganisms was examined by PCR in all samples, with primers selected for the five microorganisms that showed the most qualitative difference between CRC patients and HCs. Thus, it is aimed to determine the biomarker candidates that can be used in the diagnosis of causative agents of colorectal cancer and to quantify these microorganisms, making them easy and inexpensive parameters for routine diagnosis. With these data, we found a slight increase in the richness and diversity of fecal bacterial species in CRC patients compared to the HC group. We found that HC saliva samples have greater biodiversity and richness than CRC saliva samples. It was also observed that there was a significant difference in stool samples between patients with CRC and HC, but no such difference in saliva samples. Firmicutes, Proteobacteria and Bacteroidetes were found to be the most abundant phyla in saliva and stool samples from CRC patients and HCs. A decrease in Furmicutes and an increase in Bacteroidetes andFusobacteria phyla were detected in stools of CRC patients compared to HCs. While there was no significant change in these phyla in saliva samples, an increase in Actinobacteria and a decrease in Proteobacteria were detected in CRC patients compared to HCs. Fusobacterium and Prevotella were found to be significantly higher in the stool samples of CRC patients, and these two bacteria were thought to have the potential as a diagnostic biomarker for CRC. In addition, in our study, we observed differential enrichment in various pathways in patients when comparing microbiota between groups. These were determined as the pathways with the most metabolic pathways and genetic, environmental and cellular processes. These results show that some microorganisms that are in the microbiota are important in the diagnosis of colorectal cancer. Therefore, this study presents results that will make important contributions to the diagnosis by evaluating cancer patients in terms of these microorganisms and increasing the awareness of clinicians. It is also suggested that new roles of these previously identified microorganisms in CRC patients treated with surgery or chemotherapy should be further investigated.

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