Increased nuclear proto-oncogene expression in hypertrophic cardiomyopathy.

Hypertrophic cardiomyopathy is characterized by an unexplained hypertrophy of the left ventricle, particularly the interventricular septum. Although point mutations in the beta-myosin chain gene have been found in several US families in familiar hypertrophic cardiomyopathy, the pathogenetic pathways leading to myocyte hypertrophy, the most important feature, are still not clear. To examine whether activation (expression) of nuclear proto-oncogenes may play a role in hypertrophic cardiomyopathy, endomyocardial biopsies from 13 patients with hypertrophic cardiomyopathy were examined using monoclonal antibodies against c-myc, c-fos and c-jun. The nuclear proto-oncogenes c-fos, c-jun and c-myc were expressed in 53, 60, and 50%, respectively, of patients with hypertrophic cardiomyopathy. In control biopsies, c-myc was detectable in only 10% of the patients, while c-fos and c-jun were always undetectable. These results show that nuclear proto-oncogenes are induced in patients with hypertrophic cardiomyopathy, although the triggering mechanisms remain unknown.