| Abstract [eng] |
Renal cell carcinoma (RCC) constitutes more than 90% of all types of kidney tumors and represents the highest mortality rate among genitourinary neoplasms. Most RCC cases are treatment-resistant which is particularly related to their extensive phenotypic variability and inter-and/or intra-tumoral molecular heterogeneity (ITH). Hypermethylation of CpG islands is a frequent and pivotal alteration in RCC; however, interfocal heterogeneity of these changes has not been extensively investigated. The main aim of this study was to determine aberrantly methylated genes in renal tumor tissue samples and evaluate their heterogeneity. The methylation status of eight genes was assessed through methylation-specific PCR (MSP), after the bisulfite conversion of the isolated DNA samples. A total of 40 (20 tumor samples, 10 peritumor samples, 10 non-cancerous samples) tissue samples were investigated from 10 patients diagnosed with renal cell carcinoma or oncocytoma. Interfocal methylation heterogeneity was found in seven out of eight analyzed genes.The highest heterogeneity index (HI) was calculated for TAC1 (0.5), while ZNF677, FBN2, PCDH8, ADAMTS19, and SFRP1 HI reached 0.2 and for FLRT2 – 0.1. ZNF677, FBN2, and PCDH8 demonstrated the highest variation in methylation frequency between the two randomly selected tumor foci (20%). The highest methylation frequency in peritumor samples was detected for ZNF677 (50%), TAC1 (50%) FBN2 (40%), and PCDH8 (30%). All individuals exhibited methylation disparities between urine and tissue samples. Taken together, this study revealed that RCC is highly heterogeneous and highlights the challenge of using specific gene methylation statuses as reliable diagnostic biomarkers for early disease detection due to their heterogeneity.  . |
