JS-K, a GST-activated nitric oxide generator, induces DNA double-strand breaks, activates DNA damage response pathways, and induces apoptosis in vitro and in vivo in human multiple myeloma cells

Tanyel Kiziltepe, Teru Hideshima, Kenji Ishitsuka, Enrique M. Ocio, Noopur Raje, Laurence Catley, Chun-Qi Li, Laura J. Trudel, Hiroshi Yasui, Sonia Vallet, Jeffery L. Kutok, Dharminder Chauhan, Constantine S. Mitsiades, Joseph E. Saavedra, Gerald N. Wogan, Larry K. Keefer, Paul J. Shami and Kenneth C. Anderson
This article has an Erratum 110(13):4187


Here we investigated the cytotoxicity of JS-K, a prodrug designed to release nitric oxide (NO) following reaction with glutathione S-transferases, in multiple myeloma (MM). JS-K showed significant cytotoxicity in both conventional therapy-sensitive and -resistant MM cell lines, as well as patient-derived MM cells. JS-K induced apoptosis in MM cells, which was associated with PARP, caspase-8, and caspase-9 cleavage; increased Fas/CD95 expression; Mcl-1 cleavage; and Bcl-2 phosphorylation, as well as cytochrome c, apoptosis-inducing factor (AIF), and endonuclease G (EndoG) release. Moreover, JS-K overcame the survival advantages conferred by interleukin-6 (IL-6) and insulin-like growth factor 1 (IGF-1), or by adherence of MM cells to bone marrow stromal cells. Mechanistic studies revealed that JS-K–induced cytotoxicity was mediated via NO in MM cells. Furthermore, JS-K induced DNA double-strand breaks (DSBs) and activated DNA damage responses, as evidenced by neutral comet assay, as well as H2AX, Chk2 and p53 phosphorylation. JS-K also activated c-Jun NH2-terminal kinase (JNK) in MM cells; conversely, inhibition of JNK markedly decreased JS-K–induced cytotoxicity. Importantly, bortezomib significantly enhanced JS-K–induced cytotoxicity. Finally, JS-K is well tolerated, inhibits tumor growth, and prolongs survival in a human MM xenograft mouse model. Taken together, these data provide the preclinical rationale for the clinical evaluation of JS-K to improve patient outcome in MM.

  • Submitted October 19, 2006.
  • Accepted March 12, 2007.
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