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目的 探讨抗癌生物活性肽-S(ACBP-s)对人胃癌细胞MGC-803细胞周期和凋亡的影响.方法 (1)体外实验:以不同浓度ACBP-S处理人胃癌MGC-803细胞,采用二苯基溴化四氮唑蓝(MTT)法测定增殖抑制率;电镜下观察细胞凋亡现象;流式细胞术分析细胞周期与凋亡率;逆转录聚合酶链反应(RT-PCR)和免疫细胞化学方法检测p27基因mRNA和蛋白表达的变化.(2)动物体内实验:建立裸鼠胃癌移植瘤模型,每只裸鼠经尾静脉注射7μg ACBP-S,隔日给药,2周后处死,计算抑瘤率;HE染色观察肿瘤细胞形态变化;免疫组化法检测Bcl-2、Bax和增殖细胞核抗原(PCNA)的表达.结果 (1)5.0、10.0和15.0μg/ml的ACBP-S均能抑制MGC-803细胞的生长,且随浓度增加和作用时间延长抑瘤率增加.电镜下可见,MGC-803细胞经15.0μg/ml ACBP-S作用48h后,呈现典型的凋亡特征.流式细胞术分析结果显示,5.0和20.0μg/ml ACBP-S作用MGC-803细胞24h的凋亡率较高,分别为(5.7±0.2)%和(13.9±0.6)%(P<0.05);20.0μg/ml ACBP-S可使G0/G1期MGC-803细胞的构成比明显上升.ACBP-S上调MGC-803细胞p27基因mRNA和蛋白的表达.(2)ACBP-S能抑制胃癌移植瘤的生长,抑制率达34.2%.镜下可见,治疗组肿瘤组织中出现大片坏死及大量凋亡细胞,异型细胞及核分裂相减少.免疫组化分析结果显示,治疗组Bcl-2和PCNA表达降低,Bax表达增高.结论 ACBP-S能抑制人胃癌MGC-803细胞增殖,其作用机制与调控胃癌细胞的细胞周期和凋亡有关.

Objective To explore the impact of anti-cancer bioactive peptide-S (ACBP-S) on cell proliferation, cell cycle and apoptosis in human stomach cancer cell line MGC-803 cells. Methods (1)The cultured MGC-803 cells were treated with ACBP-S at various concentrations for 24, 48, 72h, respectively. The inhibition rate of proliferation of MGC-803 cells were evaluated by MTT assay. Cell apoptosis was observed by transmission electron microscopy. Cell cycle and apoptosis were analyzed by flow cytometry (FCM). RT-PCR was used to assay the changes of p27 mRNA expression. Immunocytochemistry was used to detect the changes of expression of p27, PCNA, Bax, Bcl-2 proteins, respectively. (2) a nude mouse xenograft model with gastric carcinoma cell was established. ACPB-S was administered into the tail vein of the mice in a dose of 7 μg, every other day, and the mice were killed after two weeks. The tumors were taken off for further analysis. Results (1) ACBP-S at concentrations of 5.0, 10.0 and 15.0 μg/ml inhibit the growth of MGC-803 cells in a concentration- and time-dependent manner. The concentration of ACBP-S at 20.0 μg/ml showed an inhibition rate of (86.6+0.1)%. Typical apoptotic changes were observed under the transmission electron microscope, the result of FCM in the range of 5.0 and 20.0 μg/ml for24h showed higher early apoptosis rates, (5.7 0.2)% arid (13.9 0.6)%, respectively, with s significant difference compared with that of the control group (P<0.05). The ratio of G0/G1 was significantly increased with the increase of incubation time at 20μg/ml. RT-PCR showed that the expression of p27mRNA in MGC-803 cells was markedly increased after ACBP-S treatment. (2) After ACBP-S administration the tumor growth in nude mice was inhibited by 34.2%. More apoptotic and necrotic cells were observed in the mice of treatment group by histological examination with HE staining. The immunocytochemistry demonstrated that the expression of Bax protein was significantly increased and Bcl-2 and PCNA protein expressions were significantly decreased after ACBP-S treatment. Conclusion ACBP-S has marked inhibiting effect upon the growth of MGC-803 cells inducing more apoptosis. The anti-cancer mechanism is probably related with its regulatory effects on cell cycle and apoptosis in the tumor cells.