Аннотация:Abnormalities involving the short arm of chromosome 3 are frequently reported in carcinomas of the kidney, lung, breast, ovary, cervix and other epithelial tumors. Detailed mapping of allelic deletions from 3p in five tumors (approx. 400 T/N DNA samples) revealed the new region in 3p21.31 (D3S2409-D3S3667, 600 kb). Frequencies of HD were found rather high in D3S2409-D3S3667 (3p21.31) region in comparison with other 3p ‘‘hot spots’’. SAGE analysis displayed tumor specific differential expression of some genes from the new D3S2409-D3S3667 region revealing features of putative oncogenes and potential TSG for the same gene. Up- and down-deregulation of the same gene in various tumor cases was also found for RARbeta2 (3p22.3), SEMA3B (LUCA region, 3p21.31-p21.2) and for USP4 and DAG1genes (D3S2409- D3S3667, 3p21.31) using RT-PCR and Real Time PCR studies. The same 3p genes were analyzed for promoter methylation. These six candidate genes were shown differentially methylated in tumor cell lines. The methylation of RAR-beta2, RASSF1A and SEMA3B in epithelial carcinomas was assayed in detail by means of methylation-specific PCR (MSP), PCR-based methylation-sensitive restriction enzyme analysis (MSRA) and bisulfite sequencing. RASSF1A gene was found highly (>60%) methylated in renal cell (RCC), breast (BC) and ovarian carcinomas (OC). Methylation of SEMA3B occurs in half (40–60%) cases of these tumors. However, methylation frequency of RAR-beta2 substantially differs between these tumor types, 60% in RCC vs. 27% in OC. At the same time methylation status of RASSF1A and SEMA3B was shown in significant positive correlation to tumor progression (stage, grade and metastases potential). Thus, diagnostics and prognostics markers can be designed.