Abstract 2617: uPAR and cathepsin B knockdown-induced nuclear translocation of JNK inhibits migration and induces apoptosis in glioma-initiating cells.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Treatment for glioblastoma (GBM) remains essentially palliative due to the aggressive infiltration of GBM cancer cells into normal brain tissue. In addition, the existence of a small subpopulation of highly resistant cells known as glioma-initiating cells (GICs), which escape radiation and chemotherapy-induced cell death, makes GBM currently incurable. Proteases, such as uPAR and cathepsin B that are responsible for cancer invasion and metastasis, are often detected in higher amounts in malignant tumors. In the present study, shRNA-mediated knockdown of uPAR and cathepsin B (pUC), alone or in combination with radiation, simultaneously inhibited migration and induced apoptosis of 5310 and 4910 non-GICs and GICs by regulating the JNK-MAPK pathway. Immunoblot and immunocytochemical analyses showed pUC treatment resulted in an increase in the levels of the phospho-JNK (p-JNK), which was mostly localized to the nucleus. We also observed an increase in the levels of p-JNK with radiation and with full-length uPAR and cathepsin B; however, it was confined to the cytoplasm of the cells. Depletion of cytosolic p-JNK with pUC treatment and/or with the JNK inhibitor decreased migration by downregulating the expression of the migratory molecules. Immunoprecipitation analysis and co-localization studies further confirmed the involvement of the cytosolic p-JNK in promoting migration of the glioma cells. The increase in the expression of nuclear p-JNK with pUC treatment increased the expression of apoptotic molecules, as observed by the western blot analysis. MTT assay revealed that non-GICs and GICs were rescued from pUC-induced cell death when treated in combination with a JNK inhibitor, which further confirms the importance of nuclear JNK in eliciting an apoptotic signal. In summary, cytosolic p-JNK aids cell migration while nuclear p-JNK drives cells toward cell death. As such, pUC treatment induced the translocation of p-JNK from cytoplasm to the nucleus, thereby simultaneously inhibiting migration and inducing apoptosis of non-GICs and GICs. Citation Format: Kiranmai Alapati, Divya Kesanakurti, Jasti S. Rao. uPAR and cathepsin B knockdown-induced nuclear translocation of JNK inhibits migration and induces apoptosis in glioma-initiating cells. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2617. doi:10.1158/1538-7445.AM2013-2617