Novel reversible selective inhibitor of nuclear export shows that CRM1 is a target in colorectal cancer cells

Abstract

Abbreviations: CRM1, chromosomal region maintenance 1; DMSO, dimethyl sulfoxide; EGFR, epidermal growth factor receptor; LMB, leptomycin B; NES, leucine-rich nuclear export signal; PI3K, phosphoinositide 3-kinase; RanBP1, Ran-binding protein 1.Colorectal cancer arises via a multistep carcinogenic process and the deregulation of multiple pathways. Thus, the simultaneous targeting of multiple pathways may be a promising therapeutic approach for colorectal treatment. CRM1 is an attractive cancer drug target, because it can regulate multiple pathways and tumor suppressor proteins. In this study, we investigated the anti-tumor activity of a novel reversible CRM1 inhibitor S109 in colorectal cancer. Our data demonstrate that S109 inhibits proliferation and induces cell cycle arrest in colorectal cancer cells. Mechanistically, we demonstrate that the activity of S109 is associated with the nuclear retention of major tumor suppress proteins. Furthermore, the Cys528 mutation of CRM1 prevented the ability of S109 to block nuclear export and inhibit the proliferation of colorectal cancer cells. Interestingly, S109 decreased the CRM1 protein level via proteasomal pathway. We argue that reversible CRM1 inhibitors but not irreversible inhibitors can induce the degradation of CRM1, because the dissociation of reversible inhibitors of CRM1 changes the conformation of CRM1. Taken together, these findings demonstrate that CRM1 is a valid target for the treatment of colorectal cancer and provide a basis for the development of S109 therapies for colorectal cancer.

Calpain-dependent disruption of nucleo-cytoplasmic transport in ALS motor neurons

“…Export of RanBP1 from the nucleus to the cytoplasm depends on the chromosome region maintenance 1 (CRM1)-dependent nuclear export system30, and the down-regulation of RanBP1 resulted in the death of cultured cells3738. Therefore, the finding of marked alteration of the subcellular localization of nucleo-cytoplasmic cargo proteins in this study suggests robust impairment of nuclear function due to cleavage of NPC components such as Nups by calpain in ADAR2-deficient AHCs.…”

“…Immunoreactivity for cellular apoptosis susceptibility protein (CAS), also known as exportin-2, was predominant in the nucleus of ADAR2-positive motor neurons but was faintly detected in the cytoplasm of ADAR2-deficient motor neurons. Immunoreactivity for RanBP1, which controls assembly/disassembly of certain karyopherin-cargo complexes30, was predominantly cytoplasmic in ADAR2-positive motor neurons but was nuclear or undetectable in ADAR2-deficient motor neurons (Fig. 3b and Supplementary Fig.…”

Association of XPO1 Overexpression with NF-κB and Ki67 in Colorectal Cancer

“…It is well known that the sustained proliferation is one of the cancer hallmarks acquired during cancer development and progression (Hanahan and Weinberg, 2011). In this regard, we identified that the overexpression of XPO1 was strongly associated with Ki67 expression, which in turn reflected the implication of XPO1 overexpression in mislocalization of essential cell cycle inhibitory proteins such as p27, p53, cyclins and some apoptotic proteins (Nguyen et al, 2012;Niu et al, 2015) lead to unregulated cell division and increased tumor size. Despite ascending tendency of XPO1 expression was noticed with increased tumor…”

“…The number of HT29 cells with Ki67 expression was dramatically and significantly decreased in HT29 KPT-330-treated groups compared to the control, and this confirmed the anti-proliferative effect of KPT-330. In fact, the inhibition of XPO1 activity induced G1 cell cycle arrest with the loss of S, G2, and M phases within hours of application followed by increase of nuclear cell cycle inhibitory proteins such as p27 and p53 (Niu et al, 2015). Normally, the Ki67 is degraded and decreased continuously in G0 and G1, which indicate the decrease of protein synthesis and then accumulate from S to M phases, which indicate an increase of cells proliferative activity.…”

“…The ability of KPT-330 to inhibit the HT29 cell lines colonies formation was assessed by the colony formation assay as described previously (Niu et al, 2015). Briefly, 10 2 HT29 cells were seeded into 24-well plates in triplicates and then treated with vehicle control (DMSO) and series doses of KPT-330, 0.5, 1, 2µmol/L) for 24 hours.…”