CRM1 inhibitor anti-tumor activity is enhanced with salicylates by S-phase arrest and impaired DNA-damage repair

Chromosome region maintenance protein1 (CRM1) mediates protein export from the nucleus and is a new target for anti-cancer therapeutics. Broader application of KPT-330 (Selinexor), a CRM1 inhibitor approved for myeloma, has been limited by toxicity. We found that combining choline salicylate (CS) with low-doses of KPT-330 (K+CS) had potent synergistic activity across blood and solid organ cancers ex-vivo and in-vivo. Mechanistically, K+CS enhances CRM1 degradation, induces potent inhibition of CRM1 mediated nuclear export, and arrests cells in S-phase with simultaneous reduction of Rad51 causing impaired DNA damage repair. K+CS represents a potential new class of therapy for multiple cancer types. JEKO-1 cells were treated with the drug conditions KPT-330, choline salicylate(CS), KPT-330+CS (K+CS) or DMSO control for 48 hours. RNA was extracted using the AllPrep DNA/RNA FFPE kit (Qiagen, Germany). Sequencing libraries were prepared using TruSeq RNA Library Prep kit V2 (Illumina, San Diego, CA) and analyzed on a HiSeq 4000 sequencer (Illumina, San Diego, CA). Sequenced reads were aligned to the hg38 reference using the previously published MAP-RSeq pipeline slightly modified to use the STAR aligner. Gene-level read counts based on Ensembl version 78 were analyzed using edgeR to find differentially expressed proteins. For this, gene counts were normalized using TMM method to remove batch effects. Normalized read counts were compared across experimental groups using a negative binomial generalized log-linear model. A total of four group comparisons were performed: KPT-330 vs. control, CS vs. control, K+CS vs. control and CS vs. KPT-300. For each comparison, genes with an adjusted p-value (Benjamini-Hochberg) ≤ 0.05 and an absolute log2 (fold change)>2.0 were considered as significantly differentially expressed and saved for further analysis.