Abstract 3445: The role of p38/MAPK14 in cerebellar granule neuron precursor proliferation and medulloblastoma

Abstract

Abstract Development of the cerbellum occurs primarily postnatally and is marked by a rapid proliferation of cerebellar granule neuron precursors (CGNPs). This proliferation requires the activity of the mitogen Sonic Hedgehog (Shh). CGNPs are proposed to be the cells of origin for some classes of medulloblastoma (MB), the most common solid pediatric tumor, making their proliferation an attractive target for cancer therapy. Since MAP kinases play important roles in many aspects of development, proliferation, and cancer, we investigated if any of the three major classes of MAP kinases were involved in Shh-driven CGNP proliferation. We have previously shown that p42/p44 ERK MAP kinases are not involved in Shh signaling in CGNP proliferation. We have also shown that JNK/SAP kinases are not involved in Shh-driven proliferation. However, p38/MAPK14 is induced and activated in proliferating CGNPs compared to CGNPs that exit the cell cycle and differentiate in the absence of Shh. Other known pathway components upstream and downstream of MAPK14, such as ASK1, MKK3 and ATF-2, are also activated in the presence of Shh. Antioxidants such as lipoic acid and n-acetyl-cysteine that relieve oxidative stress reduced Shh-induced activation of MAPK14 and caused a marked decrease in CGNP proliferation measured by Ki67 and BrdU staining. Knocking down p38 in CGNPs also causes a marked decrease in Shh-dependent proliferation and an increase in apoptosis, which indicates a role for MAPK14 in CGNP survival. We are currently investigating the mechanism of Shh regulation of p38 MAPK pathway, which will lead to a better understanding of CGNP proliferation, cerebellar development, and MB progression. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 3445. doi:10.1158/1538-7445.AM2011-3445