LIV-1 suppression inhibits HeLa cell invasion by targeting ERK1/2-Snail/Slug pathway

It was reported that expression of the estrogen-regulated zinc transporter LIV-1 was particularly high in human cervical cancer cell line HeLa. This result prompted us to study the role that LIV-1 played in human cervical cancer. The results of real-time PCR showed that LIV-1 mRNA was significantly higher in cervical cancer in situ than in normal tissues. RNAi mediated suppression of LIV-1 in HeLa cells significantly inhibited cell proliferation, colony formation, migration, and invasive ability, but had no effect on cell apoptosis. Furthermore, LIV-1 suppression is accompanied by down-regulation of p44/42 MAPK, phospho-p44/42 MAPK, Snail and Slug expression levels. Hence, our data provide the first evidence that LIV-1 mRNA is overexpressed in cervical cancer in situ and is involved in invasion of cervical cancer cells through targeting MAPK-mediated Snail and Slug expression.     

Smad4 is essential for down-regulation of E-cadherin induced by TGF-beta in pancreatic cancer cell line PANC-1

Smad4 is a tumour suppressor gene frequently deleted in pancreatic cancer. To investigate the roles of Smad4 deficiency in invasive and matastatic capabilities of pancreatic cancer, we examined the effects of Smad4 deficiency on regulation of the invasion suppressor E-cadherin in pancreatic cancer cell line PANC-1. TGF-beta decreased expression of E-cadherin and beta-catenin proteins at the plasma membrane, increased Snail and Slug mRNA expression, and induced fibroblastoid morphology in PANC-1 cells. These effects of TGF-beta were abrogated in Smad4-knocked-down PANC-1 cells. We also found that TGF-beta-induced down-regulation of E-cadherin expression was partially inhibited in Snail- and Slug-knocked-down PANC-1 cells. Thus, Smad4 mediates down-regulation of E-cadherin induced by TGF-beta in PANC-1 cells, at least in part, through Snail and Slug induction. These results suggest that Smad4 deficiency observed in invasive and metastatic pancreatic cancer might not be linked to the loss of E-cadherin.