金丝桃苷逆转长春新碱诱导的人结肠癌细胞多药耐药及其机制研究

Multidrug resistance (MDR) is one of the main obstacles limiting the efficacy of clinical chemotherapy treatment for tumors. Calcium antagonists is used as clinical tumor MDR reversal agents to regulate the P-gp level and block efflux pump function now.But they have high side effects and poor effects.So searching for highly effective and lowly toxic reversal agents for MDR is a hot field in regard to cancer drug development.Hyperin as active component of low toxicity in traditional Chinese medicine has calcium antagonistic effect.Our previous report had shown that it has excellent antitumor in vitro and in vivo.The most sensitive cell line to hyperin is HCT8 cell line.In addition, it also has cytotoxic effect on HCT8/VCR tumor cells.The mechanism of activity is probably linked to the P-gp level regulation and enhancing the sensitivity of vincristine-induced apoptosis.We will study the reversal effect and mechanism of hyperin on resistance to vincristine to confirm our hypothesis.These findings further support the potential of hyperin to be used in clinical trail of cancer treatment.The results will have certain theoretical significance and application value.

肿瘤多药耐药是当今肿瘤治疗中化疗失败的主要原因，现在已进入临床的肿瘤多药耐药逆转剂多为钙拮抗剂,通过逆转耐药细胞药物外排泵P-gp水平,阻断外排泵功能,达到耐药逆转作用，但毒副作用大，效果较差。因此筛选高效低毒的具有钙拮抗作用的肿瘤多药耐药逆转剂是近几年的研究热点。金丝桃苷作为具有钙拮抗作用的低毒中药活性成分，我们首次发现，无论体内、体外均具有极好的抗肿瘤作用,特别是对结肠癌无论是敏感细胞株（HCT8）还是长春新碱耐药株（HCT8/VCR）都效果显著。推测其耐药逆转机制也与逆转细胞P-gp水平及恢复其凋亡敏感性有关。迄今国内外尚无此方面报道。为了证实我们的假设，本课题选择HCT8/VCR细胞为研究对象，拟通过检测金丝桃苷对P-gp的表达水平以及凋亡存活通路中关键蛋白的影响，对其耐药逆转作用及机制进行研究，进而为将金丝桃苷应用为肿瘤耐药逆转剂提供依据，其成果必将具有一定的理论意义和应用价值。

钙拮抗剂作为肿瘤多药耐药逆转剂,通过逆转耐药细胞药物外排泵P-gp水平,阻断外排泵功能,达到耐药逆转作用，但毒副作用大，效果较差。金丝桃苷作为具有钙拮抗作用的低毒中药活性成分，在前期工作的基础上，推测金丝桃苷具有耐药逆转作用。本项目经过研究发现金丝桃苷可通过恢复耐长春新碱结肠癌细胞的凋亡敏感性及逆转耐长春新碱结肠癌细胞P-gp水平从而达到耐药逆转作用，其逆转机制可能是通过提高Caspase 蛋白活性，降低线粒体膜电位，降低P-gp、肺耐药相关蛋白LRP及抗凋亡因子bcl-2的表达，提高凋亡促进因子Fas表达有关。