Germline hepatocyte nuclear factor 1alpha and 1beta mutations in renal cell carcinomas.

Mutations in one copy of the hepatocyte nuclear factors (HNF) 1alpha and 1beta homeodomain containing transcription factors predispose the carrier to maturity-onset diabetes of the young (MODY) types 3 and 5, respectively. Moreover, previous identification of biallelic inactivation of HNF1alpha in hepatocellular adenoma identified its tumor suppressor function in hepatocarcinogenesis. The seminal observation of an ovarian carcinoma in a MODY5 patient who subsequently developed a chromophobe renal cell carcinoma, prompted us to screen for HNF1beta and HNF1alpha inactivation in a series of 20 ovarian and 35 renal neoplasms. Biallelic HNF1beta inactivation was found in two of 12 chromophobe renal carcinomas by association of a germline mutation and a somatic gene deletion. In these cases, the expression of PKHD1 (polycystic kidney and hepatic disease 1) and UMOD (Uromodulin), two genes regulated by HNF1beta, was turned off. Interestingly, in two of 13 clear cell renal carcinomas, we found a monoallelic germline mutation of HNF1alpha with no associated suppression of target mRNA expression. In normal and tumor renal tissues, we showed the existence of a network of transcription factors differentially regulated in tumor subtypes. We identified two related clusters of co-regulated genes associating HNF1beta, PKHD1 and UMOD in the first group and HNF1alpha, HNF4alpha, FABP1 and UGT2B7 in the second group. Finally, these results suggest that germline mutations of HNF1beta and HNF1alpha may predispose to renal tumors. Furthermore, we suggest that HNF1beta functions as a tumor suppressor gene in chromophobe renal cell carcinogenesis through a PKHD1 expression control.