Published online Jul 28, 2014. doi: 10.3748/wjg.v20.i28.9497
Revised: February 14, 2014
Accepted: April 8, 2014
Published online: July 28, 2014
AIM: To investigate the effect of knockdown of Forkhead box M1 (FoxM1) on the proliferation and invasion capacities of human gallbladder carcinoma (GBC)-SD cells.
METHODS: Four FoxM1 shRNAs were transfected into GBC-SD cells with Lipofectamine 2000 to select the appropriate shRNA for down-regulation of FoxM1. A recombinant lentivirus for shFoxM1 (Lv-shFoxM1), which expresses FoxM1-speciﬁc shRNA, and a negative control carrying green fluorescent protein, which expresses a scrambled RNA, were constructed. After transfection with the recombinant adenovirus and screened with puromycin, RT-PCR and Western blot were utilized to evaluate the inhibition efficiency. Cell viability was evaluated by MTT assay, and cell migration and invasion were assessed using the Transwell system. Cells were suspended in serum-free medium and seeded into Transwell inserts either uncoated (for migration assay) or coated (for invasion assay) with growth factor-reduced Matrigel. To verify the involvement of FoxM1 in the senescence of tumor cells, staining of senescence β-galactosidase (SA β-gal), the widely used biomarker of cellular senescence, was also performed.
RESULTS: After successful transfection of four FoxM1 small interfering RNAs (shRNAs) with Lipofectamine 2000, the shF1822 was selected as the most appropriate shRNA according to its obvious inhibitory effect. The recombinant adenovirus was then constructed with the shF1822 and successfully transfected into the GBC-SD cells, resulting in the significant inhibition of FoxM1 expression at both the mRNA and protein levels, compared with the negative control (P < 0.05). After transfection, down-regulation of FoxM1 significantly inhibited cell viability according to the MTT assay (P < 0.05). In addition, Transwell migration and invasion assays also suggested the suppression of invasion ability of the transfected cells. SA β-gal staining showed that down-regulation of FoxM1 could induce more senescent GBC cells (P < 0.05), suggesting the possible involvement of the senescence process of the FoxM1-deficient cells in GBC.
CONCLUSION: FoxM1 is functionally involved in viability of GBC cells, partially dependent on the inducement of cellular senescence, and is a potential target for GBC therapy.
Core tip: Gallbladder cancer is characterized by early metastases, thus it is in urgent need to identify novel therapies to enhance the therapeutic effect. We have previously reported that Forkhead box M1 (FoxM1) expression was closely correlated with gallbladder carcinoma differentiation, Nevin stage and metastasis, indicating the potential roles of FoxM1 in gallbladder carcinoma. In this study, by regulating the expression of FoxM1 with small interfering RNAs, we demonstrated the impact of FoxM1 on cellular viability in a human gallbladder carcinoma cell line, which was probably via the regulation of cellular senescence, revealing FoxM1 as a potential target for gallbladder carcinoma therapy.