VOLUME 6 NUMBER 2 (July to December 2013)

Phil. Sci. Lett. 2013 6 (2) 153-167
available online: August 30, 2013

*Corresponding author
Email Address: gloryranches@yahoo.com
Submitted: May 26, 2013
Revised: July 26, 2013
Accepted: July 30, 2013

ARTICLE

Heptylprodigiosin induces apoptosisin Jurkat leukemia T cells via CD95death receptor and evades antiapoptoticBcl-2 and Bcl-xL proteins

by Glory D. Ranches1*, Anita Rudy2, Angelika Vollmar2, Jortan O. Tun1 andGisela P. Concepcion1

1The Marine Science Institute, University of the Philippines, Diliman, Quezon City 1101, Philippines
2Center of Drug Research, Ludwig-Maximilians University of Munich, Munich, Germany
Heptylprodigiosin (HPDG) is a cytotoxic tripyrolemetabolite isolated from a marine bacteriumPseudovibrio denitrificans strain Z143-1. In thisstudy, we investigated the mechanism by whichHPDG induces cytotoxicity in human leukemiaJurkat T cells. HPDG-induced apoptosis (classic apoptosis) wasshown by G0/G1 arrest and DNA fragmentation that isconcentration- and time-dependent in CD95 (Fas/Apo-1)-sensitive Jurkat T cells (S-Jurkat). The MTT cytotoxicity assay isconsistent with the apoptosis assay showing an IC50 of ~2 μM inS-Jurkat T cells. HPDG-mediated apoptosis in S-Jurkat T cells isdependent on caspase activation based on a caspase 3-likeactivity assay and the time-dependent immunoblot analysis ofcaspases. Flow cytometry analysis of CD95-deficient JurkatR,Jurkat/FADD-/-, Jurkat/caspase 8-/-, and vector control cells(Jurkat/A3), showed that HPDG-induced apoptosis requires theCD95 receptor, FADD, and caspase 8. Immunoblot analysis anda mitochondrial dissipation assay revealed delayed activation ofthe intrinsic pathway. HPDG-treated Jurkat/Neo, Jurkat/Bcl-2+/+and Jurkat/Bcl-xL+/+ cells showed that HPDG-induced apoptosisis independent of Bcl-2 and Bcl-xL overexpression, suggestingthat HPDG is unaffected by the protective mechanism of theseanti-apoptotic proteins in Jurkat T cells. This is the first report ofthe apoptotic mechanism of HPDG that may have clinical utilityas a potent chemosensitizer to tumor cells with CD95expression, dysfunctional apoptosome activity, andoverexpressed Bcl-2 and Bcl-xL proteins.

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