CYCLIN D1 EXPRESSION IN RENAL CARCINOMAS AND ONCOCYTOMAS - AN IMMUNOHISTOCHEMICAL STUDY

Cyclin D1 plays an important role in cell cycle progression from G(1) to S phase. Cyclin DI overexpression has been identified in many human neoplasms, including a variety of carcinomas. A systematic study of c yclin D1 expression in renal carcinomas and oncocytomas has not been r eported. Ninety-six renal epithelial neoplasms, 78 renal carcinomas (4 5 clear-cell, 18 papillary, and 15 chromophobe), and 18 oncocytomas we re analyzed immunohistochemically using routinely fixed tissue section s and a cocktail of two monoclonal anti-cyclin D1 antibodies. One thou sand cells were manually counted, and the percentage of cyclin D1 posi tive cells was calculated. Fluorescence in situ hybridization studies using chromosome 11 centromeric and 11q13 specific probes were perform ed on a subset of clear-cell carcinomas and oncocytomas. Cyclin D1 imm unoreactivity was observed in 23 (51%) of 45 clear-cell, 5 (28%) of 18 papillary, and 2 (13%) of 15 chromophobe carcinomas. Nine (50%) of 18 oncocytomas were positive for cyclin D1. Cyclin D1 expression in clea r-cell carcinomas did not correlate with survival. Fluorescence in sit u hybridization studies on eight clear-cell carcinomas and seven oncoc ytomas revealed normal chromosome 11 number and no evidence of amplifi cation of the 11q13 locus. Thus, cyclin D1 can be immunohistochemicall y demonstrated in approximately one-half of renal oncocytomas and clea r-cell carcinomas and is less frequent in papillary and chromophobe ca rcinomas. The mechanism of cyclin D1 expression is unknown, but it doe s not seem to be related to extra copies of chromosome 11 or to gene a mplification.