Opposite effects of protein kinase C beta1 (PKCbeta1) and PKCepsilon in the metastatic potential of a breast cancer murine model.

In this paper we investigated whether protein kinase C (PKC) beta1 and PKCepsilon, members of the classical and novel PKC family, respectively, induce phenotypic alterations that could be associated with tumor progression and metastatic dissemination in a murine model of breast cancer. Stable overexpression of PKCbeta1 in LM3 cells altered their ability to proliferate, adhere, and survive, and impaired their tumorigenicity and metastatic capacity. Moreover, PKCbeta1 induced the re-expression of fibronectin, an extracellular matrix glycoprotein which loss has been associated with the acquisition of a transformed phenotype in different cell models, and exerted an important inhibition on proteases production, effects that probably impact on LM3 invasiveness and dissemination. Conversely, PKCepsilon overexpression enhanced LM3 survival, anchorage-independent growth, and caused a significant increase in spontaneous lung metastasis. Our results suggest PKCbeta1 functions as an inhibitory protein for tumor growth and metastasis dissemination whereas PKCepsilon drives metastatic dissemination without affecting primary tumor growth.