Abstract 3265: PMA induces malignant characteristics in MCF-7 breast cancer cells via MAPK-pathway

Abstract Phorbol 12-myristate 13-acetate (PMA) is a well known tumor promoter, the effect of which is mainly mediated by protein kinase C (PKC). The effect of PMA varies depending on the cell line and growth conditions. In MCF-7 breast cancer cells PMA has been found to induce growth arrest and resistance to apoptosis. Here, we studied the effects of PMA on differentiation and malignant characteristics of MCF-7 cells. The cells were grown on Matrigel besement membrane preparation or on plastic/glass surface with and without PMA, rottlerin or bryostatin. The cell proliferation assay was carried out using the cells grown on 96-well plates. Wound healing test, on glass surface, was used to detect the differences in cell migration. Activation of MAPK-pathway proteins was studied with Phospho-kinase array. When grown on Matrigel, the addition of PMA to cell culture medium increased the motility of the cells and induced dramatic morphological changes, leading to the formation of web-like multicellular structures. These changes were not observed when the cells were grown on plastic or glass surface. However, PMA caused a two-fold increase in the migration of the cells on glass surface. Furthermore, the PMA treated cells had lower proliferation rate than the untreated cells. Preincubation of the cells with PKC-inhibitors rottlerin or bryostatin abolished the effects of PMA, suggesting that these effects are mediated by PKC. PMA also induced several changes in the phosphorylation of different proteins involved in MAPK-pathway. Our results confirm the previous findings showing that PMA induces malignant characteristics in MCF-7 breast cancer cells. Morphological differentiation was only seen when the cells were grown on basement membrane preparation, recapitulating the physiological growth environment of the cells better than the artificial plastic surface. Furthermore, our results indicate that the effects of PMA on MCF-7 cells are mediated by MAPK-pathway. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 3265. doi:1538-7445.AM2012-3265