KPT-330 inhibition of chromosome region maintenance 1 is cytotoxic and sensitizes chronic myeloid leukemia to Imatinib

Abstract

As tyrosine kinase inhibitors (e.g., Imatinib, IM) fail to induce long-term response in some chronic myeloid leukemia (CML), novel therapies targeting leukemia-dysregulated pathways are necessary. Nuclear-cytoplasmic trafficking of proteins play a key role in the development of leukemia and drug resistance. KPT-330 (Selinexor), an inhibitor of chromosome region maintenance 1 (CRM1, nuclear receptor exportin 1, XPO1), demonstrated activities against a few hematological malignancies. We examined the anti-leukemic efficacy of KPT-330 in IM-resistant CML. Cell viability was examined by MTS assay. Apoptosis and cell cycle were assessed by flow cytometry. CRM1 mRNA was detected by PCR. Expression of CRM1 protein and its cargo proteins were determined by western blot or immunofluorescent staining. Furthermore, we engrafted nude mice subcutaneously with IM-resistant CML K562G. Mice were treated with IM, KPT-330 alone or in combination. Expression of CRM1 in CML were markedly higher than control. KPT-330 inhibited proliferation, induced cell cycle arrest and apoptosis of K562 and K562G. IC50 of IM on K562G was reduced by KPT-330. Mechanistically, KPT-330 inhibited CRM1 and increased the nuclear/cytoplasm ratio of BCR-ABL and P27. p-AKT was downregulated while p-STAT1 and caspase-3 were upregulated. Furthermore, KPT-330 showed anti-leukemic effect in primary IM-resistant CML with T315I mutation in CRM1-dependent manner. In K562G xenograft mice model, KPT-330 inhibited tumor growth and sensitized K562G to IM in vivo. To conclude, KPT-330 showed anti-leukemic activity and sensitized CML to IM in CRM1-dependent manner in vitro and in vivo. KPT-330 represents an alternative therapy for IM-refractory CML, warranting further investigation of CRM1 as therapeutic target.

Salicylates enhance CRM1 inhibitor antitumor activity by induction of S-phase arrest and impairment of DNA-damage repair

“…38 Previous studies have shown that KPT-330 single agent treatment leads to G 0 /G 1 cell cycle arrest and some have reported that KPT-330 single agent treatment could result in decreased expression of CRM1 and Rad51, leading to a DNA damage phenotype. 8,[39][40][41][42][43][44][45][46][47][48][49][50] Further, in MCL cell lines, KPT-330 has been shown to induce G 0 /G 1 phase arrest and could overcome inherit ibrutinib resistance through NFkB inhibition. 51 In our experimental model, we did not find a significant decrease in CRM1 or Rad51 expression with single agent KPT-330 treatment ( Figure 4G and supplemental Figure 1B).…”

AMP‐activated protein kinase activation primes cytoplasmic translocation and autophagic degradation of the BCR‐ABL protein in CML cells

“…In previous studies, BCR‐ABL localization was examined mostly by immunofluorescent detection of exogenous proteins with Abs against BCR and/or c‐ABL 35‐37 . However, this experimental system cannot distinguish BCR‐ABL from normal BCR and c‐ABL proteins derived from residual alleles.…”

“…In previous studies, BCR-ABL localization was examined mostly by immunofluorescent detection of exogenous proteins with Abs against BCR and/or c-ABL. [35][36][37] However, this experimental system cannot distinguish BCR-ABL from normal BCR and c-ABL proteins derived from residual alleles. To circumvent this issue, we generated a BCR-ABL junction-specific Ab to detect only the e14a2-type BCR-ABL protein by immunocytochemistry ( Figure S2).…”

Selinexor decreases HIF-1α via inhibition of CRM1 in human osteosarcoma and hepatoma cells associated with an increased radiosensitivity

“…For a variety of solid tumors, overexpression of CRM1 has been shown. In patients with osteosarcoma and in preclinical models of hepatocellular carcinoma cell lines, a correlation between the expression of CRM1 and cancer proliferation was demonstrated (Yao et al 2009 ; Zheng et al 2014 ).…”