Adenovirus-mediated siRNA targeting c-Met inhibits proliferation and invasion of small-cell lung cancer (SCLC) cells.

BACKGROUND

The hepatocyte growth factor receptor c-Met and its ligand hepatocyte growth factor (HGF) have been reported to be involved in cellular motility, growth, and invasion by activating mitogenic signaling pathways. The overexpression of c-Met gene has been found in many malignant cancers, but the roles of c-Met overexpression in SCLC tumors still remain unclear. The aim of the present study was to explore its roles and potential as a therapeutic target for SCLC.

METHODS

Quantitative real-time RT-PCR and immunohistochemistry assays were performed to detect the expression of c-Met mRNA and protein in SCLC tissue or corresponding non-tumor lung tissue samples. Adenovirus-mediated small interfering RNA (siRNA) was employed to down-regulate the expression of c-Met gene in SCLC cell line (NCI-H446). MTT and colony formation assays were performed to detect in vitro proliferation of NCI-H446 cells. In vitro wound-healing and transwell invasion assays were performed to detect in vitro invasion and metastasis of NCI-H446 cells. Finally, in vivo tumorigenicity and metastasis assays were done to analyze in vivo proliferation and metastasis of NCI-H446 cells in a xenograft model.

RESULTS

We showed that the levels of c-Met mRNA expression were significantly higher in SCLC tissue samples (0.97±0.08) than those in corresponding non-tumor lung tissue samples (0.21±0.02; P<0.05). Additionally, the immunostaining of c-Met protein in SCLC tissues was stronger than that in corresponding non-tumor tissues. Adenovirus-mediated siRNA targeting c-Met could significantly down-regulate c-Met expression, and the specific down-regulation of c-Met expression in SCLC cells could strongly inhibit proliferation of SCLC cells both in vitro and in vivo. Moreover, c-Met down-regulation could also reduce invasion capacity in vitro and metastasis capacity in vivo of SCLC cells.

CONCLUSIONS

Taken together, our results indicated that the overexpression of c-Met gene played an important role in the progression and development of SCLC, and adenovirus-mediated siRNA targeting c-Met could potentially be an experimental approach for SCLC gene therapy.