2151

Radiation exposure triggers the progression of triple negative breast cancer via stabilizing ZEB1

Our present study confirmed radiation can promote the in vitro migration and invasion of triple negative breast cancer (TNBC) cells and increase the expression of epithelial-mesenchymal transition (EMT) related transcription factor ZEB1, while had no effect on Snail, Slug or Twist. Knockdown of ZEB1 attenuated radiation induced cell migration and invasion, suggesting that ZEB1 is essential for radiation induced progression of TNBC. Radiation increased the protein stability of ZEB1, while had no effect on its mRNA expression. Particularly, the upregulation of ATM, which can phosphorylate and stabilize ZEB1, was involved in radiation induced upregulation of ZEB1. Collectively, we found that radiation can promote the migration, invasion and EMT of TNBC cells through stabilization of ZEB1 via ATM signals.

Post-transcription mediated Snail stabilization is involved in radiation exposure induced invasion and migration of hepatocarcinoma cells

Increasing evidences suggested that radiotherapy can paradoxically promote tumor invasion and metastatic processes, while its detailed mechanism is not well illustrated. Our present study found that radiation can promote the migration and invasion of hepatocellular carcinoma (HCC) cells via induction of epithelial mesenchymal transition (EMT), which was evidenced by the results that radiation induced up regulation of vimentin while down regulation of E-Cadherin. As to the EMT-related transcription factors, radiation increased the expression of Snail, while not Slug, ZEB1 or TWIST. This was confirmed by the results that radiation increased the nuclear translocation of Snail in HCC cells. However, radiation had no effect on the expression or half-life of Snail mRNA. In HCC cells treated by cycloheximide (CHX, the translation inhibitor), radiation significantly increased the half-life of Snail protein, which suggested that radiation increased the expression of Snail via up regulation of its protein stability. Radiation increased the expression of COP9 signalosome 2 (CSN2), which has been reported to block the ubiquitination and degradation of Snail. Silence of CSN2/Snail can attenuate radiation induced cell migration and EMT of HCC cells. Collectively, our data suggested that radiation can promote HCC cell invasion and EMT by stabilization of Snail via CSN2 signals.