Antitumor Activities Of Cetuximab In Combination With Radiotherapy In Human Gastric Carcinoma Cell Lines MGC803 And BGC823

Purpose:1.To study the effect of C225 combined with radiotherapy on the proliferation of human gastric carcinoma cell lines MGC803 and BGC823,and to evaluate the synergenic effect of the combination.2.To observe the cell cycles distribution and apoptosis of human gastric carcinoma cell lines MGC803 and BGC823 treated by C225 in combination with radiotherapy .3.To observe the expression of EGFR signaling pathway proteins induced by C225 in combination with radiotherapy on human gastric carcinoma cell lines MGC803 and BGC823.4.To explore the primary mechanism of C225 in combination with radiotherapy according to the results of the experiment.Methods:MGC803 and BGC823 cells were added in RPMI-1640 medium supplemented with 10%FBS,100u/mL penicillin,and100u/mL streptomycin,cultured in a humidif- ied 5%CO2/95% air atmosphere at 37℃.1.While cells proliferated in logarithm,the effect of C225 alone or radiotherapy alone,or the combination on the proliferation of MGC803 and BGC823 cells was evaluated by MTT assay,and Q value was calculated to assess the combined effect.2.The carcinoma cell lines were inoculated in 6-hole plates, then divided into four groups, receiving no treatment, or C225 alone , or X-ray alone , or the combonation respectively. Flow cytometry(FCM)analysis was applied to detect the distribution of cells cycle and apoptosis.3.The carcinoma cell lines were inoculated in 6-hole plates, then divided into four groups, receiving no treatment, or C225 alone , or X-ray alone , or the combonation respectively .Werstern-blotting was used to detect the expression of EGFR,p-Akt and p-p38MAPK, respectively. Results:1.C225 used alone inhibited the proliferation of MGC803 and BGC823 cells. With the concerntration of C225 ranging from 0.1ug/ml-1000 ug/ml, the inhibition effect increased positively, which showed significantly statistical difference compared with the control group. X-ray alone also inhibited the proliferation of MGC803 and BGC823 cells. With the dose of X-ray ranging from 2-6Gy, the inhibition effect increased positively, significantly different from the control group.2.The combination of C225 and X-ray could obviously inhibit the proliferation of MGC803 and BGC823 cells, which showed synergistic effect.3.The combination of C225 and X-ray could induce more G0/G1arrest of the MGC803 and BGC823 cells, while the propotion of cancer cells in phase S decreased signifcantly, and result in more apoptosis. 4.The combination of C225 and X-ray could decrease the expression of EGFR,p-Akt and p-p38MAPK, the EGFR signaling pathway proteins.Conclusion:1. C225 or X-ray alone could inhibit the proliferation of human gastric carcinoma cell lines MGC803 and BGC823,and exihibit synergistic effect when combined.2. The mechanism of synergistic effect of C225 in combination with X-ray may be attributed to the inhibition of EGFR signaling pathway, which resulted in: (1) the proportion of cancer cells increased in phase G0/G1, and decreased in phase S; (2) more apoptosis were induced. Consequently, the proliferation inhibition effect on gastric cancer cells were enhanced.