Expression Of EGFR And VEGFR In Prostate Cancer Cell Line DU145 Treated With Gefitinib

0bjective:To investigate the influence of Gefitinib,a selective epidermal growth factor receptor(EGFR)-tyrosine kinase inhibitor,on the proliferation and the expression of EGFR and VEGFR in androgen-independent prostate cancer cell line DU145.Methods:Prostate cancer cell line DU145(2×10~4/ml)was cultured with Gefitinib of different concentration (0～20umol/L) for 24,48,72,96,120h in vitro and the effects of Gefitinib on the proliferation in DU145 cells was measured by MTT assay. After the cells(1×10~5/ml)being cultured with Gefitinib of different concentration (0～20umol/L) for 48h,its morphological and ultrastructure change was analyzed by optical microscopy and laser confocal microscopy;flow cytometry was used to examine the distribution of cell cycle;the DNA-fragment methed was used to study the apoptosis induced by Gefitinib;the expression of protein EGFR and VEGFR was analyzed by Western blot technique.Results: DU145 cells were incubated in DMEM in vitro and passaged for 2～3 days.MTT colorimetric method showed that Gefitinib could inhibit the proliferation of DU145 cells in a dose and time dependent manner. The best concentration of Gefitinib which inhibited DU145 cells was l0umol/L,and the best time was 48h.The results of flow cytometry showed that Gefitinib could induce an arrest of ce1l cycle in G1 phase. Typical morphological change could be observed after treatment with Gefitinib,including nuclear chromatin condensation,fragmentation,cell shrinkage and formation of apoptosis bodies. With the DNA-fragment methed we can find the appearance of typical DNA ladder. Analysis on expression of EGFR and VEGFR by Western blot showed that the proteins can be highly expressed(0.835±0.102,0.419±0.134).After being cultured with Gefitinib, the expression of EGFR and VEGFR can decreased with different lever: 0.749±0.031 and 0.383±0.124(2.5umol/L),0.470±0.087 and 0.358±0.133(5umol/L),0.388±0.147 and 0.219±0.087(10umol/L),0.117±0.074 and 0.089±0.029(20umol/L). Compared with normal control group, the percentage of descent of protein EGFR and VEGFR respectively were:10.92% and 8.59%(2.5umol/L),43.71% and 14.56% (5umol/ L),53.53% and 47.64%(10umol/L),85.98% and 78.76%(20umol/L).The statistics analysis confirmed that Gefitinib could inhibit the expression of EGFR and VEGFR(p<0.05).Conclusions: Gefitinib has significant growth inhibiting effect on DU145 cells and the apoptosis in DU145 cells could be induced by it in this study.The molecular mechanism of apoptosis may be related to the down regulation of expression of EGFR and VEGFR.