The Study Of Herceptin Enhanced Cytotoxicity Of Chemotherapy To Human Breast Carcinoma MDA-MB453 Cells

[Objective] To investigate the effect and mechanism of Herceptin on drug sensitivity of Cisplatin, Navelbine, Adriamycin, Vepesid, Gemcitabine and Taxotere in combined treatment, and then offer evidence for clinical application.[Methods] To choose the high expression of HER-2 cell lines with immunocytochemical methods for the study. The inhibited rates of human breast carcinoma cells (MDA-MB453) treated by single Herceptin, single chemotherapy, and combined treatment of Herciptin and chemotherapy in different sequences were determined with MTT colorimetric assay. The changes in cell cycle of cells of every group were analysed by flow cytometry (FCM).[Results]1 MDA-MB453 cell over-expresses HER-2 (3+).2 Chemotherapeutic agents(HER,DDP,NVB,TXT,GEM,ADM,VP-16) could suppress proliferation or kill MDA-MB453 cells in vitro.3 The MTT colorimetric assay shows:(1) the group that TXT was used 18h later than HER achieved maximum inhibition rate (P<0.05) and the interaction was synergistic ;(2) These groups that using NVB after HER or using NVB 30h later and further than HER achieved better inhibiton than the monotherapy group of NVB (P<0.01), and showed synergistic interaction;and the group that using HER 10h after NVB got the minimum inhibition and indicated antagonism;(3) The combinations of HER and DDP achieved better inhibition than the monotherapy of NVB (P<0.01), and showed additive interaction; And the simultaneous treatment was best ;(4) All sequential groups of ADM and HER got better inhibition than the monotherapy of ADM (P<0.01) and these groups using HER 12h later and further than ADM were better (P>0.05) and showed synergism;(5) Applying HER beforeor simultaneously with GEM could get better inhibition than GEM only(P<0.01) ;and the inhibition of the groups of using HER after GEM was lower than GEM only;the simultaneous combination was best and indicated addition effect (6)The inhibition of the groups using HER 6h before VP16 was best and showed addition effect.4, Flow cytometry showed that: (1) Herceptin(HER) could induce G₁ arrest; (2) Chemotherapeutic drug(TXT) alone arrested cell cycle progression in G₂/M phase. Compared with the group of chemotherapy alone, the proportions of S phase cells in the group of HER18h before chemotherapy, increased obviously while the proportions of G₂/M phase cells decreased.Howevere,changes of the group using HER 6h after TXT was opposite, (3) Single chemotherapeutic drug(NVB) arrested cell cycle progression in G2/M phase. Compared with the group of single chemotherapy, the group using HER 10h after NVB resulted in the decrease of proportions of G₀/G₁ phase and the increase of S G₂/M phase ; and other groups were opposite;(4) Single chemotherapeutic drug(DDP) arrested cell cycle progression in G2/M phase. Compared with the group of single chemotherapy, the groups using HER before DDP resulted in the decrease of proportions of G₀/G₁ Sphase and the increase of G₂/M phase ; and other groups didn't show much difference;(5) Chemotherapeutic drug(ADM) arrested cell cycle progression in G₂/M phase. Compared with other groups and single chemotherapy group, the group using HER 24h after ADM resulted in the decrease of proportions of and the increase of G₂/M phase ; Accompanying the change of the sequence of the HER-ADM application, the proportions of G₀/G₁ S phase decreased and G₂/M increased gradually;(6) Single chemotherapeutic drug(GEM) arrested cell cycle progression in S G₂/M phase. Compared with the group of single chemotherapy, the groups using HER and GEM simultaneously resulted in the increase of proportions of S phase; With the change of the sequence of the HER-GEM application, the proportions of G₂/M decreased gradually;(7) Single chemotherapeutic drug(VP-16) arrested cell cycleprogression in S G₂/M phase. Compared with the group of single chemotherapy, the groups using HER before GEM ,or simultaneously induced the increase of proportions of G₁ phase.(Conclusion] Effects of combinations of herceptin and chemotherapeutic agents in different sequences is different : Combined with TXT, to use HER 18h in advance could get the best inhibiton; with NVB, to apply HER 40h later could achieve the best effect; with DDP , to administer HER after DDP could gain better inhibition; Combined with ADM, to cast HER 12h later or further could get the maximum inhibition; Combined with GEM, simultaneous combination was the best choice; with Vepesid ,pre-cast HER 6h could get better effect.And Its mechanism may be related to the cell cycle changes.