PKC-Inhibitors Induce Apoptosis by Inhibiting Hsp70-Mediated Protection of Anti-Apoptotic Bcl2 Proteins in Dalton’s Lymphoma Cells

Abstract

BACKGROUND: Proteins of BCl2 family regulate mitochondria-dependent apoptotic pathway, whose down regulation induced apoptosis for which the basis is poorly understood. Therefore, aims of the present investigation were to study the effect of PKC inhibitors (chelerythrine and staurosporine) on the expression of BCl2 proteins in Dalton’s Lymphoma (DL) cells. Further, to identify whether exogenous application of tumor derived hsp70 protects DL cells from PKC-inhibitor-mediated apoptosis.

METHODS: To investigate this, cells were harvested from tumor bearing mice after 18 days of post transplantation and cultured for 48hrs in RPMI-1640 supplemented with 10% FBS and 5µg/mL pen/strep in 5% CO2 at 37℃. Cells were then treated with PKC inhibitors (CHE-10µM/STS-1µM) in the presence of HS+, cHS+ and tumor derived hsp70, immunocytochemistry, western blots, RT-PCR, caspase assay, and flowcytomery were carried out.

RESULTS: Our results showed that PKC inhibitors (CHE/STS) treatment resulted in depressed expression of BCl2 and Bcl-xL proteins in hsp70-mediated protection while Bax and Bcl-xL were found to be upregulated significantly. Altered expression of BCl2 proteins induced activation of caspase-3 and apoptosis ultimately.

CONCLUSION: PKC inhibitors (CHE/STS) treatment may contribute to develop effective therapeutic regimen against Dalton’s lymphoma.