COORDINATE EXPRESSION OF NUCLEAR AND MITOCHONDRIAL GENES INVOLVED IN ENERGY-PRODUCTION IN CARCINOMA AND ONCOCYTOMA

The expression of mitochondrial and nuclear genes involved in ATP prod uction was examined in renal carcinomas, renal oncocytomas, and a sali vary oncocytoma. Renal carcinomas were found to have a reduced mitocho ndrial DNA (mtDNA) content while oncocytomas had increased mtDNA conte nts. This parallels morphological changes in mitochondrial number in t hese tumours. In the carcinomas, mtDNA transcripts were decreased 5- t o 10-fold relative to control kidneys, suggesting that mitochondrial t ranscript levels depend on the mtDNA content. In renal oncocytomas, mt DNA transcripts were slightly reduced in spite of a high mtDNA content . However, in the salivary gland oncocytoma, mtDNA transcripts were in creased more than 10-fold in parallel with a 10-fold increase in mtDNA content. The expression of the nuclear DNA oxidative phosphorylation genes, ATPsyn beta and ANT2, was reduced up to 4-fold in renal carcino ma. In contrast, the levels of these two nuclear gene transcripts were induced about 4-fold in renal oncocytoma and up to 30-fold in salivar y gland oncocytoma. Moreover, the ANT2 precursors were observed to cha nge in oncocytomas. These data suggest a coordinated regulation of nuc lear and mitochondrial gene expression in renal carcinomas and the spe cific induction of nuclear OXPHOS gene expression in oncocytomas.