The transcriptional factor Snail simultaneously triggers cell cycle arrest and migration of human hepatoma HepG2

Abstract

Snail was recently highlighted as a critical transcriptional factor for tumor metastasis. Real time RT/PCR and Western blot analysis demonstrated that Snail mRNA and protein, respectively, were induced by 12-O-tetradecanoylphorbol-13-acetate (TPA) in hepatoma cell HepG2. Blockade of gene expression of Snail by antisense oligodeoxynucleotide and/or siRNA technique can prevent not only the TPA-triggered EMT/cell migration and growth inhibition of HepG2 but also TPA-induced down-regulation of E-cadherin and up-regulation of p15(INK4b). Moreover, the TPA-triggered promoter activation of p15(INK4b) was also prevented. On the other hand, two of the HepG2 clone over-expressing Snail, namely S7 and S15, had a scattered fibroblastic morphology and acquired higher motility than parental HepG2. Also, the proportion of G0/G1 phase of S7 and S15 was higher than that of parental HepG2, consistent with the longer doubling time of both cells. Semiquantitative RT/PCR analysis demonstrated a greatly elevated gene expression of Snail accompanied with decreased E-cadherin and increased p15(INK4b) in both Snail-overexpressing cells. On the transcriptional level, p15(INK4b) promoter activity was 2.6-fold higher in S7 as compared with parental HepG2. Furthermore, electrophoretic mobility of DNA fragments encompassing proximal p15(INK4b) promoter can be retarded by incubation of nuclear extract of S7. Our results demonstrated that Snail play diverse trans-regulatory roles in HepG2. Notably, we suggested that Snail may upregulate p15(INK4b) gene expression by directly activating its promoter.

Crosstalk between Beta-Catenin and Snail in the Induction of Epithelial to Mesenchymal Transition in Hepatocarcinoma: Role of the ERK1/2 Pathway

“…Because TPA has been reported to induce EMT-like cell scattering in HepG2 cells [27], we used U0126 to determine whether ERK1/2 activation was responsible for this process. In control conditions, HepG2 cells had an epithelial cell-like morphology with a characteristic “cobblestone” appearance and the organization of F-actin into a cortical pattern at cell-to-cell junctions (Figure 1B, arrowhead).…”

“…Previous study had shown that the EMT triggered by TPA is dependent on Snail [27]. Accordingly, we sought to determine if ERK1/2 was responsible for the Snail activation.…”

“…We therefore investigated the events underlying the EMT of hepatoma cells. We used the tumor promoter 12- O -tet-radecanoylphorbol-13-acetate (TPA), which has been reported to induce EMT in differentiated HCC cells derived from the HepG2 cell line [27]. We found that TPA-triggered ERK1/2 activation played a critical role in the onset and progression of EMT.…”

The role of the transcriptional regulator snail in cell detachment, reattachment and migration

“…36 Snail also triggers migration of hepatoma HepG2, 37 and oesophageal squamous cell carcinoma cells. 38 Snail silencing dramatically reduced the ability of breast carcinoma MDA-MB231 cells to migrate into collagen IV.…”

Early origin of cancer metastases: Dissemination and evolution of premalignant cells

“…Accordingly, the transcription factor and EMT inducer Snail simultaneously triggers cell cycle arrest and migration of human hepatoma HepG2 by inducing p15 Ink4B . 64 An argument against this notion can be seen with the treatment of primary mouse hepatocytes deficient in p53, p21 CIP1/ WAF1 and/or Rb (singly or in combination) with TGFβ. These cells show a similar induction of EMT-morphological changes regardless of genotype and independent of proliferation index.…”