oxadiazoles and Peritoneal-Neoplasms

Survivin, which is highly expressed and promotes cell survival in diffuse malignant peritoneal mesothelioma (DMPM), exclusively relies on exportin 1 (XPO1/CRM1) to be shuttled into the cytoplasm and perform its anti-apoptotic function. Here, we explored the efficacy of Selective Inhibitors of Nuclear Export (SINE), KPT-251, KPT-276 and the orally available, clinical stage KPT-330 (selinexor), in DMPM preclinical models. Exposure to SINE induced dose-dependent inhibition of cell growth, cell cycle arrest at G1-phase and caspase-dependent apoptosis, which were consequent to a decrease of XPO1/CRM1 protein levels and the concomitant nuclear accumulation of its cargo proteins p53 and CDKN1a. Cell exposure to SINE led to a time-dependent reduction of cytoplasmic survivin levels. In addition, after an initial accumulation, the nuclear protein abundance progressively decreased, as a consequence of an enhanced ubiquitination and proteasome-dependent degradation. SINE and the survivin inhibitor YM155 synergistically cooperated in reducing DMPM cell proliferation. Most importantly, orally administered SINE caused a significant anti-tumor effect in subcutaneous and orthotopic DMPM xenografts without appreciable toxicity. Overall, we have demonstrated a marked efficacy of SINE in DMPM preclinical models that may relay on the interference with survivin intracellular distribution and function. Our study suggests SINE-mediated XPO1/CRM1 inhibition as a novel therapeutic option for DMPM.

Topics: Acrylamides; Active Transport, Cell Nucleus; Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cyclin-Dependent Kinase Inhibitor p21; Dose-Response Relationship, Drug; Enzyme-Linked Immunosorbent Assay; Exportin 1 Protein; G1 Phase Cell Cycle Checkpoints; Humans; Hydrazines; Inhibitor of Apoptosis Proteins; Karyopherins; Lung Neoplasms; Mesothelioma; Mesothelioma, Malignant; Mice; Mice, SCID; Neoplasm Proteins; Oxadiazoles; Peritoneal Neoplasms; Real-Time Polymerase Chain Reaction; Receptors, Cytoplasmic and Nuclear; Survivin; Thiazoles; Triazoles; Tumor Suppressor Protein p53

The new chemical entity GIT-27NO was created by the covalent linkage of a NO moiety to the anti-inflammatory isoxazoline VGX-1027. The compound has been shown to possess powerful anticancer effects both in vitro and in vivo. However, its effects on nonsolid and metastatic forms of tumors have not yet been investigated. We have studied the effects of GIT-27NO on the highly invasive mouse mammary TA3Ha cell line in vitro and in vivo. In contrast to the conventional exogenous NO donor sodium nitroprusside, GIT-27NO successfully enhanced intracellular NO concentration in TA3Ha cells. Intracellular accumulation of NO was followed by marked decrease in TA3Ha cell viability accompanied by typical apoptotic features. Interestingly, inverted membrane phosphatidylserine residues, reduced volume of nucleus, condensed chromatin, and terminal fragmentation of DNA were associated with inhibited caspase-3 activity and transcription of the genes encoding caspase-3, -8, and -9. In parallel, GIT-27NO rapidly but transiently prevented the loss of p53 through phosphorylation on Ser 20 and provided the necessary signals for the execution of downstream processes without p53 de novo synthesis. The caspase-independent apoptotic-like death process triggered by GIT-27NO could be mediated by markedly down-regulated expression of the antiapoptotic Bcl-2 molecule observed in TA3Ha cells exposed to GIT-27NO. In agreement with these in vitro data, GIT-27NO efficiently suppressed the growth of the ascites form and associated lethality of tumor induced by TA3Ha cells in mice.

Topics: Acetates; Animals; Caspase 3; Caspase 8; Caspase 9; Caspases; Cell Death; Cell Line, Tumor; Cell Survival; Down-Regulation; Female; Mammary Neoplasms, Experimental; Mice; Nitric Oxide; Oxadiazoles; Oxazoles; Peritoneal Neoplasms; Proto-Oncogene Proteins c-bcl-2; Tumor Suppressor Protein p53