Downregulation of c-Met expression does not enhance the sensitivity of gastric cancer cell line MKN-45 to gefitinib.

The aim of the present study was to investigate the effect of downregulation of the c‑Met gene on signal transduction and apoptosis in gastric cancer MKN‑45 cells; furthermore, the study aimed to determine whether altered c‑Met gene expression affected MKN‑45 sensitivity to gefitinib. Three c‑Met‑specific small interfering RNAs (siRNAs) were synthesized and transfected into MKN‑45 cells. Messenger RNA (mRNA) and protein levels of c‑Met and its downstream signaling molecules [phosphoinositide 3‑kinase (PI3K) and AKT] were examined using reverse transcription polymerase chain reaction and western blot analysis 48 h following transfection. Cell apoptosis was evaluated using Annexin‑V/propidium iodide double staining and fluorescence‑activated cell sorting analysis. An MTT assay was performed in order to measure the 50% inhibitory concentration (IC50) of gefitinib on MKN‑45 cells. The results of the present study demonstrated that 48 h post‑transfection with c‑Met siRNA, MKN‑45 cells showed significantly downregulated expression of c‑Met mRNA and protein as well as an increased rate of apoptosis (P<0.05). In addition, following c‑Met siRNA transfection mRNA and protein levels of PI3K and AKT were not significantly altered in MKN‑45 cells (P>0.05); however, a marked decrease in the expression levels of phosphorylated (p)‑PI3K and p‑AKT was observed (P<0.05). Furthermore, the IC50 of gefitinib in MKN‑45 cells was not significantly decreased. In conclusion, knockdown of the c‑Met gene promoted gastric cancer cell apoptosis and inhibited downstream p‑PI3K and p‑AKT; however, the sensitivity of MKN‑45 cells to gefitinib was not increased.