The Inhibition Effect Of ZD₁₈₃₉ Combined With DDP To Human Ovarian Clear Cell Adenocarcinoma Cell Line ES-2

Objective:To observe the selective epidermal growth factor receptor (EGFR) tyrosine kinase inhibitor gefitinib (ZD1839), whose inhibitory effect of monotherapy and combination with cisplatin and docetaxel to the human ovarian clear cell adenocarcinoma (OCCA) cell line ES-2. Meanwhile, to explore its mechanism. Use ZD1839 combined with DDP or DTX and traditional TP (DDP combined DTX) regime, to compare their inhibition efficacy to ES-2. To find a new effective regime to OCCA's clinic chemotherapy.Methods:Use MTT method to assay chemotherapeutic drugs' inhibition rate (Fa) to OCCA cell line ES-2; Analyze and compare the inhibition effect of monotherapy and combination therapy. Use flow cytometry to assay OCCA cell line ES-2'cell cycle distribution and its early, late and total apoptosis rate.Results:(1) DDP, gefitinib and docetaxel, whose monotherapy and combination can inhibit the growth of ES-2 cells, and the inhibition was time and concentration dependent (P<0.01). The 24h ICSO of DDP, gefitinib and docetaxel were 35.31ug/mL,2.77ug/mL and 3.59ug/mL, respectively. Among the monotherapy groups, ZD1839 group had the lowest IC50, and the strongest inhibitory effect (F=14129.74, P<0.01). Among the combined Groups, ZD1839 combined DDP or DTX group had lower IC50 and stronger inhibitory effect than the group DDP combined DTX's (P< 0.01). (2) 24 hours after combined DDP with ZD1839, when Fa<0.6, the combination index CI< 1, and the two drugs were synergistic; when Fa≥0.6, the combination index CI> 1, and the two drugs were antagonistic. After 48 hours combination, the two drugs were synergistic.24 hours after ZD1839 combined with DTX, when Fa≤0.5, the combination index CI<1, and the two drugs were synergistic. After 48 hours combination, when Fa<0.8, the combination index CI< 1, and the two drugs were synergistic. (3)The early, late and total apoptosis rates of experimental groups were significantly higher than the control group's (F=115.62,81.48,327.07; P <0.01,0.01, 0.01). Among the monotherapy groups, Group gefitinib's early apoptosis rate was significantly higher than the other two groups (17.8% vs 9.65%, 9.17%; F=47.34, P<0.01). Among the six experimental groups, gefitinib combined DDP group's total apoptosis rate was 50.43%, which was the highest of all the groups. Conversely, DDP group had only 16.94% total apoptosis rate, which was the lowest. (4) After application 2.5ug/mL of the gefitinib 24 hours, the G1 phase cells were increased 1.05 times than the control group (98.23% vs 43.07%).Conclusions:(1) Gefitinib can inhibit human ovarian clear cell adenocarcinoma ES-2 cell line's growth, and it can also enhance the antitumor ability of DDP and docetaxel. The inhibition was time and concentration dependent. The 24h IC50 of DDP, gefitinib and docetaxel were 35.31ug/mL,2.77ug/mL and 3.59ug/mL, respectively.(2) Among the monotherapy groups, the IC50 of ZD1839 group was the lowest and the inhibitory effect was the strongest. It indicated that using ZD1839 in the clinical treatment of OCCA may enhance the effect of chemotherapy.(3) This antitumor mechanism may be related to the detention of G1 phase and induction of tumor cell apoptosis.(4) The inhibition of gefitinib combined DDP or docetaxel to ES-2 cell line were significantly higher than the traditional TP (DDP and DTX) regimen. For OCCA patients especially those resistant to TP regimen, the trial of ZD 1839 may get better treatment efficacy.