Abstract
Anaplastic thyroid carcinoma (ATC) is one of the most lethal malignancies having no effective treatment. Exportin-1 (XPO1) is the key mediator of nuclear export of many tumor suppressor proteins and is overexpressed in human cancers. In this study, we examined the therapeutic potential of selinexor (XPO1 inhibitor) against human ATC cells both in vitro and in vivo. Here, we showed that XPO1 is robustly expressed in primary ATC samples and human ATC cell lines. Silencing of XPO1 by either shRNA or selinexor significantly reduced cellular growth and induced cell cycle arrest, apoptosis of ATC cells by altering the protein expression of cancer-related genes. Moreover, selinexor significantly inhibited tumor growth of ATC xenografts. Microarray analysis showed enrichment of DNA replication, cell cycle, cell cycle checkpoint and TNF pathways in selinexor treated ATC cells. Importantly, selinexor decreased AXL and GAS6 levels in CAL62 and HTH83 cells and suppressed the phosphorylation of downstream targets of AXL signaling such as AKT and P70S6K. Finally, a combination of selinexor with doxorubicin demonstrated a synergistic decrease in the cellular proliferation of several ATC cells. These results provide a rationale for investigating the efficacy of combining selinexor and doxorubicin therapy to improve the outcome of ATC patients.
Highlights
Anaplastic thyroid carcinoma (ATC) is one of the most lethal malignancies having no effective treatment
Nuclear staining of XPO1 was observed in 77% (30 of 39) of papillary, 75% (6 of 8) of follicular and 90% (10 of 9) of anaplastic thyroid carcinoma
Protein expression of XPO1 was examined in a panel of ATC cell lines (OGK-M, HTH83, CAL62, T238, SW1736, HTH7, HTH74, C643 and ATC351); and each had strong XPO1 protein expression (Fig. 1B)
Summary
Anaplastic thyroid carcinoma (ATC) is one of the most lethal malignancies having no effective treatment. Exportin-1 (XPO1) is the key mediator of nuclear export of many tumor suppressor proteins and is overexpressed in human cancers. A combination of selinexor with doxorubicin demonstrated a synergistic decrease in the cellular proliferation of several ATC cells These results provide a rationale for investigating the efficacy of combining selinexor and doxorubicin therapy to improve the outcome of ATC patients. Selinexor (KPT-330; Karyopharm Therapeutics, Newton, MA, USA) is a first-in-class, oral selective inhibitor of XPO1 resulting in blockade of nuclear export. This compound selectively binds to the Cys[528] of XPO1, thereby inhibiting XPO1 binding to the NES domains of its cargo protein. Selinexor, when combined with doxorubicin showed increased anticancer activity
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