PKC alpha expression is a marker for breast cancer aggressiveness

Background: Protein kinase C (PKC) isoforms are potential targets for breast cancer therapy. This study was designed to evaluate which PKC isoforms might be optimal targets for different breast cancer subtypes. Results: In two cohorts of primary breast cancers, PKC alpha levels correlated to estrogen and progesterone receptor negativity, tumor grade, and proliferative activity, whereas PKC delta and PKC epsilon did not correlate to clinicopathological parameters. Patients with PKC alpha-positive tumors showed poorer survival than patients with PKC alpha-negative tumors independently of other factors. Cell line studies demonstrated that PKC alpha levels are high in MDA-MB-231 and absent in T47D cells which proliferated slower than other cell lines. Furthermore, PKC alpha silencing reduced proliferation of MDA-MB-231 cells. PKC alpha inhibition or downregulation also reduced cell migration in vitro. Conclusions: PKC alpha is a marker for poor prognosis of breast cancer and correlates to and is important for cell functions associated with breast cancer progression.