To elucidate the relationship between
tumor genesis and the mitochondrial energy metabolism in
renal neoplasms, we studied three individual
enzyme activities of the oxidative phosphorylation, two components of the Krebs cycle and the
mitochondrial DNA content of
renal carcinomas including 29 conventional, five papillary, two unclassified
carcinomas with sarcomatoid features and one
collecting duct carcinoma. A significant reduction of all mitochondrial
enzyme activities including
complex V, as well as of the
mitochondrial DNA content was detected in 34 of 37
renal carcinoma tissues as compared with control kidney. Mitochondrial
enzyme activities and
mitochondrial DNA levels were not statistically different between the conventional, papillary and unclassified sarcomatoid type of
renal carcinoma and did not correlate with tumour grade,
metastasis, ploidy and proliferative activity as determined by Ki-67 staining. Taken together, our data indicate that a co-ordinated down-regulation of all components necessary for mitochondrial energy metabolism occurs in most
renal carcinomas as an early event in
carcinoma formation, which does not change with progression of the disease.