Effects Of Experimental Chemoendocrine Therapy With A Combination Of Tamoxifen And Adriamycin On Breast Cancer Cell Line MCF-7 And On Xenograft Animal Model

Part 1.The Effects of Tamoxifen and Adriamycin in combination on Growth and Apoptosis in Breast Cancer Cell Line MCF-7Objective To study the effect of tamoxifen and adriamycin in combination on breast cancer cell line MCF-7(ER+).Methods Estrogen receptor(ER)-positive MCF-7 human breast cancer cell line was treated by tamoxifen (TAM) or adriamycin(ADM) alone ,or TAM and ADM in combination. Cell proliferation was evaluated by MTT assay. The distribution of cell cycle and the rate of apoptosis were determined by flow cytometry.Results Both tamoxifen and adriamycin can inhibit MCF-7 cells proliferation and induce their apoptosis. The cells were arrested in G0/G1 phase by tamoxifen and in G2/M phase by adriamycin respectively. The inhibition of cell proliferation and the change of cell cycle kinetics induced by tamoxifen were time-dependent and dose-dependent. When tamoxifen and adriamycin are used in combination, the inhibitory effect on proliferation and apoptosis was not markedly enhanced, while the level of G0/G1 phase cells was raised.Conclusions When used as a single agent, both tamoxifen and adriamycin can significantly inhibit MCF-7 cells growth and proliferation and induce their apoptosis; but when the two drugs are administrated in combination, the therapy effect cannot be improved, which suggests that they are not synergic.Part 2.Effects of Experimental Chemoendocrine Therapy with the Combination of Tamoxifen and Adriamycin on Breast Cancer Xenograft Animal ModelObjective To study the anti tumor effect of an experiemental chemoendocrine therapy with the combination of tamoxifen and adriamycin on MCF-7 human breast cancer cells(ER+) implanted in nude mice.Method Each Balb/c nude mouse was injected subcutaneously with 2 x 106 ER positive human breast cancer cell line MCF-7 to establish breast cancer xenograft animal model. When the volume of lumps grew to about 150mm3, experimental animals were divided into four groups: TAM group, in which each nude mouse was fed with TAM(5mg/kg) every day; ADM group, in which each mouse was administrated ADM intravenously every five days; TAM and ADM in combination group, in which each nude mouse was both fed with TAM(5mg/kg) every day and given ADM intravenously every five days; and control group. The treatment course was 30 days, when the volumes of tumor were detected every five days and eventually all the mice were killed and tumors were completely removed. Then they were cut in half after measuring the volume and weight in each mouse. In one half, tumor cells were analyzed by flow cytometry to detect the distribution of cell cycle and the rate of apoptosis. In the other , the expressions of cyclinDl, PCNA and bcl-2 protein were detected by immunohistochemistry method.Results(l)Compared with the control group ,the increase of tumor volume in nude mice was inhibited in all therapy groups (including TAM group, ADM group and TAM+ADM group). But there was no significant difference (P > 0.05) in tumor volume changes among the three therapy groups.(2) Cell cycle analysis by flow cytometry (FCM) showed that the percentage of G0/G1 phase cells was increased in all therapy groups. Thepercentage of G0/G1 phase cells of the TAM group was 82.4 2.3 %, much higher than that of the other two therapy groups, which suggested the cells were arrested in G0/G1 phase. The proliferating index (PI) decreased in all the therapy groups ,but there was no significant difference(P > 0.05) among them. Both TAM and ADM induced apoptosis of tumor cells. Compared with TAM group, the apoptosis rate in ADM group and TAM+ADM combination group was lower (P < 0.05).(3) Detected by immunohistochemistry method, the expressions of cyclinDl, PCNA and bcl-2 protein were rather high in control group. The expression of PCNA in three therapy groups was lower. As for cyclinD1 , the expression levels in TAM group and combination group decreased significantly, but didn't change much in ADM group. In addition, no significant change in the expression of bcl-2 in all therapy...