Protein kinase C is not involved in the homologous desensitization of bombesin responses in small cell lung cancer cells.

Homologous desensitization of responses to bombesin in small cell lung cancer cells can be mimicked by protein kinase C-activating phorbol esters. We show that phorbol ester-induced desensitization can be blocked by prior treatment with the protein kinase C inhibitor staurosporine or prolonged pretreatment with phorbol esters. However, under these conditions, homologous desensitization to bombesin persists. These data indicate that phorbol ester-induced desensitization is distinguishable from bombesin-induced homologous desensitization. Protein kinase C is not a dominant component in the homologous desensitization to bombesin in small cell lung cancer cells.