Downregulation of SNAIL sensitizes hepatocellular carcinoma cells to TRAIL-induced apoptosis by regulating the NF-κB pathway

Abstract

Abstract. Hepatocellular carcinoma (HCC) is the sixth most common cancer and the second most lethal cancer worldwide. Evidence has shown HCC cell resistance to TRAIL-mediated apoptosis. In a previous study, we verified that silencing SNAIL downregulated the growth of HCC cells. In addition, the mechanism of resistance to TRAIL in HCC cells was connected with the activation of nuclear factor-κB (NF-κB). Thus, it was hypothesized that the downregultaion of SNAIL sensitizes HCC cells to TRAIL-induced apoptosis by regulating the NF-κB pathway. In the present study, the most effective lentiviral vectors carrying shRNA against SNAIL were selected and adenoviral vectors harboring TRAIL were constructed. The expression of SNAIL and TRAIL was detected by quantitative PCR and western blotting. HCC cell viability and apoptosis were assessed using an MTT assay and the Hoechst test. To determine how to sensitize HCC cells to TRAIL-induced apoptosis after silencing SNAIL, p53 was assessed by western blot analysis. We also investigated the expression of Bcl-xL, cIAP2, survivin and Raf-1 protein using western blot analysis and the apoptotic degree of HuH-7 cells was detected using the Hoechst test following the suppression of each gene, which was a possible molecular mechanism to sensitive TRAIL-induced apoptosis through the downregulation of SNAIL in HCC cells. Silencing SNAIL resulted in increased apoptosis by enhancing sensitization to TRAIL in all the HCC cells. Additionally, p53 protein was upregulated in HuH-7 cells. Expression of Bcl-xL, cIAP2, survivin and Raf-1 was downregulated following silencing of SNAIL, while down regulation of any of the proteins contributed to SNAIL suppression enhancing HCC cell sensitivity to TRAIL-induced apoptosis, with the exception of cIAP2. The results demonstrated that silencing SNAIL can sensitize TRAIL-induced apoptosis in HCC cells by upregulating p53 protein and by regulating related genes of the NF-κB pathway such as Bcl-xL, survivin and Raf-1.

High expression of Snail and NF-κB predicts poor survival in Chinese hepatocellular carcinoma patients

“…Our observation that nearly all HCC patients are positive for both Snail and NF-κB is consistent with earlier studies [8, 13, 14–16]. Previous in vitro studies also showed that activation of NF-κB signaling increases Snail expression [6, 12, 13, 17], which is consistent with our finding that levels of Snail expression correlate closely with those of NF-κB expression in human HCC samples. Taken together, the earlier in vitro findings and our present in vivo observations strongly suggest that Snail and NF-κB are key mediators in HCC [8, 9, 18].…”

A molecular signature for anastasis, recovery from the brink of apoptotic cell death

“…Snail is one of the mRNAs enriched in apoptotic cells and then highly induced in early recovery and has been reported to protect cells from apoptosis ( Inukai et al, 1999 ; Metzstein and Horvitz, 1999 ; Franco et al, 2010 ; Wan et al, 2015 ). We found that Snail protein levels increased during recovery ( Fig.…”

A Molecular Signature for Anastasis, Recovery from the Brink of Apoptotic Cell Death

“…Snail is one of the mRNAs enriched in apoptotic cells and then highly induced in early recovery, and has been reported to protect cells from apoptosis 21,22 . We found that Snail protein levels increased during recovery (Figure 5K).…”