VHL alterations in human clear cell renal cell carcinoma: Association withadvanced tumor stage and a novel hot spot mutation

To elucidate the role of somatic alterations for renal cancer etiology and prognosis, we analyzed 227 sporadic renal epithelial tumors for mutations a nd hypermethylations in the von Hippel-Lindau tumor suppressor gene VHL. Tu mors were classified according to the recommendations of the Union Internat ionale Contre fe Cancer (UICC) and the American Joint Committee on Cancer ( AJCC), Somatic VHL mutations were identified by PCR, single-strand conforma tion polymorphism analysis, and sequencing, and hypermethylations were iden tified by restriction enzyme digestion and Southern blotting, Frequencies o f VHL alterations were established, and an association with tumor type or t umor type and tumor stage was evaluated, VHL mutations and hypermethylation s were identified in 45% of clear cell renal cell carcinomas (CCRCCs) and o ccasionally (3 of 28) in papillary (chromophilic) renal cell carcinomas (RC Cs), Lack of VHL mutations and hypermethylations in chromophobe RCCs and on cocytomas was statistically significant (P = 0.0001 and P = 0.0004, respect ively), RCCs carrying VHL alterations showed, in nine cases (12%), mutation s at a hot spot involving a thymine repeat (ATT.TTT) in exon 2, Tumor stagi ng was critical to the VHL mutation/hypermethylation detection rate in CCRC Cs shown by separate evaluation of patients from medical centers in Munich, Heidelberg, and Mainz. The spectrum of pT(1), pT(2), and pT(3) CCRCCs and the VHL mutation/hypermethylation detection rate varied among these three g roups, Altogether, VHL alterations were significantly associated with pT(3) CCRCCs (P = 0.009), This is the first evidence of frequent somatic VHL mut ations at a particular site within exon 2 and an association of VHL mutatio ns/hypermethylations with a standard prognostic factor.