The Research Of Antitumor Activity Of Herceptin And Cantide On Breast Cancer Cells In Vitro And In Vivo

[Background and Objective] Breast cancer, a main reason threatened the women's health in our country, is in the top of incidence and mortality rate of all kinds of cancers.20% to 25% breast cancer patients are highly expressed HER2 protein, which induced the overactivity of the signaling pathway, the out of control of cell proliferation and the higher invasion. It is a single risk for prognosis. Recently, many researches are focused on HER2 target therapy. Trastuzumab (Herceptin) is a humanized IgG monoclonal antibody, specifically targeted against the extracellular domain of the human epidermal growth factor receptor 2 (HER2). Herceptin has already approved for advanced and adjuvant therapy of HER2 positive patients by FDA since 1998. For early breast cancer patients, herceptin combined chemotherapy significantly improved the disease-free survival and overall survival. For advanced breast cancer patients, herceptin combined chemotherapy obviously enhanced the response rate, prolonged the time to progress and overall survival. The new concept of herceptin combined other target drugs provide much more chooses of non-chemotherapy regimens for progressed HER2 positive patients. Many target drugs are combined with herceptin, including lapatinib, bevacizumab, pertuzumab, T-DM1, neratinib and so on. A lot of clinical trials have demonstrated that these drugs bring much more benefits for patients. Based on the combined target therapy of protein target and gene target, this research choose herceptin, which is a monoclonal antibody target HER2, combined with cantide, which is an antisense oligodeoxynucleotide target hTERT mRNA, to discuss the in vitro and in vivo effects on HER2 overexpressed breast cancer cells BT474 and to provide an idea and experiments evidence for the combined use of target drugs. inhibition rate of herceptin and cantide for BT474 is detected by MTT assay; 2) To observe distribution and influence of HER2 and hTERT protein in drugs by indirect immunofluorescent assay; 3) To observe the cell cycle changes by flow cytometry; 4) The apoptosis rate is detected by Annexin/PI staining and flow cytometry assay; 5) BT474 cells are inoculated to the nude mice, tumor weight and tumor volume are measured after administered herceptin and cantide to the mice.[Results] 1) The inhibition rate is observed when separately or continuously administered the two drugs through MTT assay. The synergistic effects are showed when the two drugs are combining used in the lower concentration. The additive effect is showed when the two drugs are combining used in higher concentration; 2) HER2 and hTERT protein are simultaneously expressed in BT474 cells, HER2 protein is mainly located in the cells membrane, where hTERT protein is located in cells nuclear. After administered herceptin into BT474 cells, HER2 protein is slightly migrated to cells plasma, where the location of hTERT protein is not obviously changed; 3) Cell cycles are arrested in phase G2/M when administered cantide alone, and cell cycles are arrested in phase G0/G1 when administered herceptin alone, and cell cycles are arrested in phase G0/G1 when administered the two drugs continuously; 4) Apoptosis rate is observed by Annexin/PI staining. The apoptosis rate is 16.38% when administered cantide alone, it is 16.84% when administered herceptin alone, it is 22.57% when administered the two drugs continuously, most apoptosis cells are in advanced apoptosis stage; 5) BT474 cells are inoculated to the nude mice, the tumor grows well. The inhibition rate is 43.5% when administered cantide alone, the inhibition rate is 55.41% when administered herceptin alone, the inhibition rate is 67.41% when administered the two drugs continuously.[Conclusion] 1)The in vitro researches indicated that cantide and herceptin have the inhibition effect for BT474 cells line, the inhibition rate is line with the concentration of drugs; 2) The synergistic effect is showed when the two drugs are combining used in the lower concentration. The additive effect is showed when the two drugs are combining used in higher concentration. The combination of two drugs improved the apoptosis rate; 3) The in vivo research showed herceptin or cantide inhibit the tumor growth; 4) The combination of two drugs has a higher inhibition rate, which is the additive effects.