Ixazomib induces apoptosis and suppresses proliferation in esophageal
squamous cell carcinoma through activation of the c-Myc/NOXA pathway
Abstract
BACKGROUND AND PURPOSE Esophageal squamous cell carcinoma (ESCC) is one
of the major subtypes of esophageal cancer. More than half of the ESCC
patients in the world are in China, and the 5-year survival rate is less
than 10%. As a new oral proteasome inhibitor, ixazomib has shown strong
therapeutic effect in many solid tumors. In this study, we aimed to
investigate the effects of ixazomib on the proliferation inhibition and
apoptosis of ESCC cells. EXPERIMENTAL APPROACH We used four human ESCC
cell lines, cell viability assay, cell cycle and apoptosis assay,
RT-PCR, Western blot, immunohistochemistry and ESCC xenografts model to
clarify the roles of the therapeutic effect and mechanism of ixazomib in
ESCC. KEY RESULTS Ixazomib significantly inhibited the proliferation and
induced apoptosis in ESCC cells. RT-PCR results showed that the
expression of endoplasmic reticulum stress-related gene NOXA and c-Myc
significant increase after treatment with ixazomib in ESCC cell. Then we
knockdown the NOXA and c-Myc by siRNA, the therapeutic effect of
ixazomib markedly decrease, which confirmed that c-Myc/NOXA pathway
played a key role in the treatment of ESCC with ixazomib. In vivo, the
xenograft ESCC model mice were given 10 mg/kg of ixazomib every other
day for 30 days. The results showed that the tumor size in the treatment
group was significantly smaller than the control group CONCLUSIONS AND
IMPLICATIONS These results suggested that ixazomib is known to suppress
proliferation and induce apoptosis in an ESCC cell lines, and this
effect was likely mediated by increased activation of the c-Myc/NOXA
signaling pathways.