Selective Inhibitors of Nuclear Export Block Pancreatic Cancer Cell Proliferation and Reduce Tumor Growth in Mice

Abstract

Background & Aims Tumor suppressor proteins are inactivated by many different mechanisms, including nuclear exclusion by chromosome region maintenance (CRM)-1. Increased tumor levels of CRM-1 have been correlated with poor prognosis of patients with pancreatic cancer, making it a therapeutic target. Selective inhibitors of nuclear export (SINEs) bind to CRM-1 to irreversibly inhibit its ability to export proteins; we investigated a new class of SINEs in pancreatic cancer cells. Methods We studied the effects of SINE analogs in a panel of pancreatic cancer cell lines and non-transformed human pancreatic ductal epithelial (HPDE) cells using proliferation, apoptosis, immunoblot, co-immunoprecipitation, small inhibitor (Si)-RNA, and fluorescence microscopy analyses. The effects of the SINEs were also investigated in mice with subcutaneous and orthotopic tumors. Results SINEs (KPT-185, KPT-127, KPT-205 and KPT-227) inhibited proliferation and promoted apoptosis of pancreatic cancer cells, but did not affect HPDE cells. The nuclei of cells incubated with KPT-185 accumulated tumor suppressor proteins (p27, FOXO, p73, and PAR-4) and inhibited interactions between CRM-1 and these proteins. Mutations in the region of CRM-1 that binds to SINEs (Cys-528), or siRNA knockdown of PAR-4, prevented the ability of KPT-185 to block proliferation and induce apoptosis of pancreatic cancer cells. Oral administration of KPT-330 to mice reduced growth of subcutaneous and orthotopic xenograft tumors without major toxicity. Analysis of tumor remnants showed that KPT-330 disrupted the interaction between CRM-1 and PAR-4, activated PAR-4 signaling, and reduced proliferation of tumor cells. Conclusion We identified SINEs that inhibit CRM-1 and promote nuclear accumulation of tumor suppressor proteins in pancreatic cancer cells. Oral administration of the drug to mice reduces growth of xenograft tumors.

Preclinical and clinical efficacy of XPO1/CRM1 inhibition by the karyopherin inhibitor KPT-330 in Ph+ leukemias

“…22,32 This impaired survival induced by SINEs may not only result from inhibition of XPO1 activity but also from their reported negative effect on XPO1 expression. 36,37 Indeed, XPO1 levels were found decreased in KPT-330-treated CML (CP and BC) and Ph 1 ALL CD34 1 progenitors (Figure 2A). Interestingly, 24-hour treatment with KPT-330 and imatinib (1 mM each) markedly potentiated apoptosis of IL-3-cultured BCR-ABL1 1 cells, which was nearly 95% compared with the ;30% and ;50% observed in imatinib-treated and KPT-330-treated IL-3-cultured cells, respectively ( Figure 2D), suggesting that KPT-330 inhibits both XPO1-mediated BCR-ABL1-dependent and -independent leukemogenic signals.…”

CRM1 and BRAF Inhibition Synergize and Induce Tumor Regression in BRAF-Mutant Melanoma

“…Selective inhibitors of nuclear export (SINE) also known as KPT-analogs ( Fig. 1; KPT-185, KPT-251, KPT-276, and KPT-330) are capable of binding to the Cys-528 residue in the cargo-binding portion of the CRM1 protein successfully preventing protein transport from the nucleus to the cytoplasm (5,(11)(12)(13). The interruption of the system results in nuclear accumulation of the cargo, thereby restoring or disrupting cargo function.…”

Selective inhibitors of nuclear export for the treatment of non-Hodgkin's lymphomas

“…Supplementary Figure S1 and Figure 1A). This results in locking of TSP in the nucleus of cancer cells leading to selective apoptosis in solid tumors 15,16 and hematologic malignancies. 17,18 In this proof-of-concept study, we investigated the anti-cancer potential of selective inhibitors of nuclear export (SINE) against NHL cell lines and corresponding xenograft models.…”