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XPO1 Inhibitor KPT-330 Synergizes With Bcl-xL Inhibitor to Induce Cancer Cell Apoptosis by Perturbing rRNA Processing and Mcl-1 Protein Synthesis

Zhi-Chuan Zhu, Ji-Wei Liu, Can Yang, Miao Zhao, Zhi-Qi Xiong

Cell Death Dis. 2019 May 21;10(6):395.

PMID: 31113936

Abstract:

XPO1 (exportin1) mediates nuclear export of proteins and RNAs and is frequently overexpressed in cancers. In this study, we show that the orally bioavailable XPO1 inhibitor KPT-330 reduced Mcl-1 protein level, by which it synergized with Bcl-xL inhibitor A-1331852 to induce apoptosis in cancer cells. KPT-330/A-1331852 combination disrupted bindings of Mcl-1 and Bcl-xL to Bax, Bak, and/or Bim, elicited mitochondrial outer membrane permeabilization, and triggered apoptosis. KPT-330 generally mitigated mRNA expression and protein synthesis rather than mRNA nuclear export or protein stability of Mcl-1. KPT-330 inhibited mTORC1/4E-BP1 and Mnk1/eIF4E axes, which disrupted the eIF4F translation initiation complex but was dispensable for Mcl-1 reduction and KPT-330/A-1331852 combination-induced apoptosis. Mature rRNAs are integral components of the ribosome that determines protein synthesis ability. KPT-330 impeded nucleolar rRNA processing and reduced total levels of multiple mature rRNAs. Reconstitution of XPO1 by expressing degradation-resistant C528S mutant retained rRNA amount, Mcl-1 expression, and Bcl-xL inhibitor resistance upon KPT-330 treatment. KPT-330/A-1331852 combination suppressed growth and enhanced apoptosis of non-small cell lung cancer xenografts. Therefore, we clarify the reason of apoptosis resistance of cancer cells to XPO1 inhibition and develop a potential strategy for treating solid tumors.

Chemicals Related in the Paper:

Catalog Number Product Name Structure CAS Number Price
AP522629089-B MNK1 Inhibitor - CAS 522629-08-9 MNK1 Inhibitor - CAS 522629-08-9 522629-08-9 Price
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