Glioblastoma multiforme (GBM) is the most common and deadly type of primary brain tumor, accounting for over 13,000 new cases in the U.S. annually and a two-year survival rate of < 5%. GBMs are highly invasive and classified by the World Health Organization as a grade IV astrocytoma. Recent studies have shown that protein kinase A (PKA), a key regulator of signal transduction and various biological functions, is essential for maintaining polarity during cell migration and that localized activation of PKA at the leading edge is an early event in directional cell migration of other cell types. Though PKA has previously been shown to promote proliferation and migration in lung, colorectal, adrenocortical, and prostate cancer cell lines, the molecular mechanisms that link PKA activity with GBM physiology remain unclear. Wound healing assays in human GBM cell lines U-251 MG, U-87 MG and A172, demonstrated that GBM cell migration increased following the addition of 20 μM epidermal growth factor (EGF). Similar results were found with 5 μM treatment of the adenylate cyclase activator, forskolin, and inhibited by pre-treatment with 10 μM of the PKA inhibitor, H89. In order to assay the amount of PKA activity, we measured the phosphorylation of cAMP response element binding protein (CREB) in these cell lines. Western blot studies revealed an increase in CREB phosphorylation in cells treated with EGF and forskolin. Phosphorylation of CREB was decreased with the addition of H89 treatment. Our western blot analysis supports our wound healing data demonstrating a correlation between increased PKA-mediated CREB phosphorylation and migration in the absence of serum. Taken together, these data suggest that PKA activation by EGF is involved in GBM cell migration. Moreover, our findings describe a mechanism by which PKA regulates the migration of human brain tumors.
Citation Format: Jennifer N. Ausland, Robert H. Newman, Patrick M. Martin. Protein kinase a regulation of malignant brain tumor migration. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 933.