Promoter methylation of aquaporin 1 as a prognostic biomarker in clear cell renal cell carcinoma.

Abstract

518 Background: Clear cell renal cell carcinoma (ccRCC) is the most common form of kidney cancer, yet reliable biomarkers for early detection and prognosis remain limited. We initially conducted a comprehensive screening of membrane proteins and selected Aquaporin 1 (AQP1) for further investigation based on its significantly altered expression patterns. Aberrant AQP1 expression has been implicated in ccRCC, and recent evidence suggests that its regulation via promoter DNA methylation may contribute to gene expression changes during tumor progression. Methods: We first analyzed data from The Cancer Genome Atlas (TCGA) ccRCC cohort to assess the correlation between AQP1 promoter methylation and mRNA expression levels. We then performed high-resolution bisulfite amplicon sequencing (BSAS) on approximately 53 paired ccRCC tumor and adjacent non-tumor tissue samples to map detailed methylation patterns. Methylation diversity was quantified using Shannon and Simpson indices, and clustering analysis was applied to define distinct methylation profiles. Statistical associations were evaluated between methylation states, recurrence risk (including hazard ratios), and clinicopathological parameters. Results: TCGA data revealed a significant inverse correlation between AQP1 promoter methylation and mRNA expression. In our BSAS analysis, complete promoter methylation was significantly less frequent in tumor tissues compared to non-tumor tissues. Clustering analysis demonstrated marked differences in methylation pattern composition between tumor and adjacent normal tissues. In tumor samples, high methylation levels were associated with a poor prognosis, whereas in non-tumor tissues, pronounced demethylation correlated with increased recurrence risk. Furthermore, elevated methylation entropy in both tissue types was linked to higher recurrence rates, suggesting that epigenetic heterogeneity may reflect tumor microenvironmental stress. Conclusions: AQP1 promoter methylation offers a promising prognostic ccRCC biomarker. Methylation dynamics in non-tumorous tissue could be used to develop non-invasive methods to monitor ccRCC recurrence risk. Comprehensive screening analysis of membrane proteins. Gene W W_p Variance 95% CI Lower 95% CI Upper AQP1 0.968 0.011 211.469 164.175 282.725 AQP4 0.923 <0.001 6.084 4.724 8.135 Choline_T 0.753 <0.001 253.825 197.059 339.353 ECAD 0.893 <0.001 62.859 48.801 84.04 GLUT1 0.817 <0.001 0.003 0.002 0.004 GLUT3 0.65 <0.001 20.236 15.71 27.055 LAT1 0.171 <0.001 145.687 107.536 208.577 MDR1 0.462 <0.001 11.942 9.272 15.967 MGMT 0.812 <0.001 0.027 0.021 0.036 RAD51 0.542 <0.001 0.005 0.003 0.006 RARb 0.599 <0.001 1.362 1.057 1.821 TMEFF2 0.555 <0.001 24.24 18.819 32.407