Adhesion to type V collagen enhances staurosporine-induced apoptosis of adrenocortical cancer cells

Adrenocortical carcinoma (ACC) is a rare and aggressive tumor characterized by poor prognosis and resistance to conventional chemotherapy. Many chemotherapy agents act determining apoptosis, therefore, studying the responsiveness of ACC to apoptosis inducing molecules, can help to identify possible conditions to promote cancer cell death. Tumor progression is strictly related to the interaction between cancer cells and stroma; yet, extracellular matrix remodeling regulates tumor cell proliferation and apoptosis. At this purpose, we have studied staurosporine-induced apoptosis of ACC cell line H295R adherent to different extracellular matrix molecules. H295R cells grown on plastic showed a low responsiveness to staurosporine, with an apoptotic rate of 24 %, as compared to breast cancer MCF7 cells, with an apoptotic rate of 60 %. The adhesion of H295R cells to type V collagen induced a significant increase of apoptosis up to 52 %; this effect was inhibited by anti-integrin alpha2 antibody. At the same time, the adhesion of H295R cells on polylysine, matrigel, lamimin, fibronectin, and type I-III collagens didn't modify staurosporine-induced apoptosis. Staurosporine-treated H295R cells showed an increase of PARP cleavage and of annexin-V expression, when adherent to type V collagen. Yet, staurosporine induced Akt and Erk activation on H295R cells: the adhesion on type V collagen didn't modify Akt activation, while determined a dramatic inhibition of Erk activation. The described data demonstrate that the adhesion to type V collagen specifically increases the responsiveness of ACC cells to staurosporine-induced apoptosis and that this is probably obtained through the inhibition of Erk activation.