Cofilin is a cAMP effector in mediating actin cytoskeleton reorganization and steroidogenesis in mouse and human adrenocortical tumor cells
Abstract
The cAMP pathway plays a critical role in the development of cortisol-producing adrenocortical adenomas (CPA). cAMP-induced steroidogenesis is preceded by reorganization of the actin cytoskeleton, a process regulated by cofilin activity. This study explores the role of cofilin in mediating the effects of cAMP on cell morphology and steroidogenesis in adrenocortical tumor cells. We found that forskolin induced cell rounding and significantly reduced the phosphorylated (P)-cofilin/total cofilin ratio in Y1 (-52 ± 16%, p < 0.001) and human CPA cells (-53 ± 18%, p < 0.05). Silencing cofilin attenuated both forskolin-induced morphological changes and progesterone production (1.3-fold vs. 1.8-fold in controls, p < 0.05). In contrast, transfection of wild-type or S3A (active) cofilin, but not S3D (inactive) cofilin, enhanced forskolin-induced cell rounding and resulted in a 3-fold increase in progesterone synthesis compared to controls (p < 0.05). Additionally, dephosphorylation of cofilin using a ROCK inhibitor further Colforsin amplified forskolin-induced cell rounding and steroidogenesis (2-fold increase vs forskolin alone). Western blot and immunohistochemistry analyses revealed a decreased P-cofilin/total cofilin ratio and elevated cofilin expression in CPA compared to endocrine-inactive adenomas. Collectively, these findings identify cofilin as a key mediator of cAMP-induced morphological changes and steroidogenesis in both mouse and human adrenocortical tumor cells.