Protein Kinase C Alpha Expression in Breast and Ovarian Cancer

In recent years research has focused on the development of specific, targeted drugs to treat cancer. One approach has been to block intracellular signaling proteins, such as protein kinase C alpha (PKC-α). To help support the rationale for clinical studies of a PKC-α-targeted therapy in breast and ovarian cancers, we reviewed publications studying PKC-α expression in these tumors. Since these investigations were mostly performed in cell lines, we supplemented this review with some preliminary findings from studies examining PKC-α expression in tumor tissue biopsies obtained from patients with breast and ovarian cancer. Based on the reviewed publications using representative cell lines and our preliminary findings on tumor tissue of patients with breast cancer, we infer that PKC-α levels may especially be increased in breast cancer patients with low or negative estrogen receptor (ER) levels. Thus, clinical studies determining efficacy of selective or specific inhibitors of PKC-α should include determination of ER status in order to help answer whether blocking PKC-α in patients with low or absent ER can result in clinical benefit.