Inhibitory Effects Of Celecoxib And Erlotinib In Colorectal Cancer Cell Lines HT-29 In Vitro

Objective: The human colorectal cancer cells line HT-29 was treated with selective cyclooxygenase-2(COX-2) inhibitor celecoxib,epidermal growth factor receptor (EGFR) blocker erlotinib respectively,or in combination. The expressions of COX-2 mRNA, EGFRmRNA were quantitatively analysised. The protein expressions of COX-2,EGFR were examined. The secretion of epidermal growth factor (EGF) and prostaglandinE2 (PGE2 )in HT-29 lines in vitro also be examined.Methods: Cell validity was assayed by MTT reduction test.The expressions of C0X-2mRNA,EGFRmRNA was quantitatively analysised by real-time RT-PCR. The protein expressions of C0X-2,EGFR was examined by Western blot. The concentrations of EGF,PGE2 was examined by ELISA.Results: Erlotinib and celecoxib inhibited the growth of HT-29 cells in a time- and dose-dependent manner(24-72h; Erlotinib: 10μmol/L, 25μmol/L,50μmol/L, 60μmol/L; celecoxib:220μmol/L,240μmol/L,260μmol/L,280μmol/L).Erlotinib(50μmol/L) and celecoxib(220μmol/L) inhibited the proliferation of HT-29 cells at rates of 56.9% and 56.6%, respectively, at 48h. Erlotinib and celecoxib in combination resulted in a synergistic effect on inhibiting growth, the inhibition ratio is 86.1%. Erlotinib and celecoxib down-regulated the expression levels of COX-2 mRNA,EGFRmRNA of HT-29cells, respectively, but their combination down-regulated it more significantly than signal (P<0.01). while Erlotinib and celecoxib down-regulated the expression levels of COX-2,EGFR protein of HT-29 cells, respectively,the treatment with combination group was significantly higher than those of theHT-29 cells treated by the two agents alone (P<0.05). the resepective drug group and the united drug group comparing to blank group, is statistically significant(P<0.01). Erlotinib and celecoxib reduced the secreting of PGE₂ ,EGF on cultured human colorectal cancer cell line HT-29 in vitro, respectively, the combined use of drugs decreased it more significantly than a single use of drug(P<0.01). Conclusions: EGFR receptor antagonist Erlotinib and selective COX-2 inhibitor celecoxib inhibit the growth of cultured human colorectal cancer cell line HT-29 in a time-and dose-dependent manner, both have a synergistic inhibitory effect; Erlotinib and Celecoxib inhibite the proliferation of colorectal cancer cell lineHT-29 by inhibiting the expression of COX-2 mRNA,EGFRmRNA and protein, reducingEGF,PGE2 synthesis; Erlotinib collaborated with celecoxib synergistically inhibit the production of COX-2 to reduce the synthesis of PGE2, and synergistically down-regulated the expression of EGFR to decrease the synthesis of EGF, Erlotinib and celecoxib in combination resulted in a synergistic anticancer role.