Introduction & Objectives
There is no ideal tumor marker currently available for renal cell carcinoma (RCC) with sufficient sensitivity and specificity. Recent analyses of microbiota using 16S sequencing revealed that the microbiome, above all, the gut microbiome, is associated with a number of human diseases. The aim of this study is to find out the potential tumor marker of RCC from the analyses of bladder microbiota obtained using a sterilized urine catheter.
Materials & Methods
In this study, we collected urine samples from 44 RCC patients and 25 interstitial cystitis patients, 16 other-cancer patients, and 75 samples as healthy controls using a sterilized urine catheter to avoid urethral infection, because urethral microbiota are increased by a million times through the urethra. Using a total of 160 urine samples, PCR amplification of the 16S rDNA, of which the V4 region was amplified, sequencing, and analyses were performed by Seibutsugiken Inc. The study protocol was approved by the Ethics Committees of the Graduate School of Medical Sciences, Kyushu University, and Harasanshin Hospital (permission no: 2022-170). Written informed consents were obtained from all patients. Data Analyses: Histogram of species distribution: For an optimal appearance, the top 10 species at each level were selected, and the rest were combined as others. Cladograms: the evolutionary history and relatedness of species. Alpha diversity: Chao1 index was used to describe species abundance. Shannon index was used to describe species diversity. Beta Diversity: Unweighted UniFrac Principal Coordinates Analysis (PCoA) distance was implemented, facilitating two-dimensional graph visualization.
Results
The microbial composition was certainly obtained from urine samples via a sterilized urine catheter. 818 bacteria were identified from 160 urine samples. The histograms of species distribution (Fig. 1A) and cladogram (Fig. 1B) interestingly demonstrated that the Streptococcus genus was significantly expressed in the microbiota from RCC patients compared with other groups. However, fewer Bradyrhizobium, Ralstonia, and Fenollaria genera were expressed than in the control group. Microbial alpha diversity demonstrated that Chao1 analysis indicated no significant difference between any groups, but the RCC group reflected more diversity in comparison to the healthy group, significantly in Shannon analysis (Fig. 1C). Microbial beta diversity demonstrated that significant variations were observed between each group (Fig. 1D).
Conclusions
Our present study suggests that analyzing bladder urine microbiota composition and diversity promisingly identifies potential tumor markers for RCC.
