HERG钾通道在肿瘤细胞的表达与阿霉素化疗敏感性的关系及红霉素的调节作用

Correlation of HERG K+ Channel Protein Expression to Chemosensitivity of Tumor Cells to Doxorubicin and Its Modulation by Erythromycin

背景与目的:HERG钾通道在许多肿瘤组织中表达,而在肿瘤起源的相应正常组织中却是低表达或不表达。本研究探讨HERG钾通道蛋白在肿瘤细胞的表达及其与阿霉素化疗敏感性的关系,同时观察红霉素的生化调节作用。方法:采用Westernblot法检测HERG钾通道蛋白在肿瘤细胞的表达情况,经过质粒的分离和纯化、基因转染技术、MTT法研究HERG钾通道蛋白的表达与阿霉素的抗肿瘤作用的关系,同时采用MTT法检测红霉素的抗肿瘤作用及其与阿霉素联用时的协同作用,荧光显微镜观察阿霉素进入肿瘤细胞的情况。结果:HERG在不同肿瘤细胞的表达量不同,表达较高的HT鄄29细胞对阿霉素敏感性比表达较低的A549细胞弱。将herg基因转染入表达较低的A549细胞后,从IC50来看,阿霉素的增殖抑制作用明显降低。红霉素能明显抑制HT鄄29细胞的增殖,与阿霉素联用能协同抑制HT鄄29细胞的增殖。herg转染入A549细胞后,阿霉素在肿瘤细胞内的含量基本没有改变。结论:HERG钾通道蛋白的表达与阿霉素的化疗敏感性可能呈一种负相关。红霉素对HERG高表达的HT鄄29细胞增殖具有明显的抑制作用,而对HERG低表达的A549细胞基本无作用,且与阿霉素联用存在明显的协同作用。

BACKGROUND ＆ OBJECTIVE： Previous studies have found that HERG, a kind of K＋ channel protein, is expressed in some cancers, but its expression is weak or lost in normal tissues. This study was to investigate HERG expression in various cancer cell lines, its correlation with chemosensitivity of cancer ceils to doxorubicin, and its biochemical modulation. METHODS. HERG expression in human colon carcinoma cell line HT-29, human breast carcinoma cell line MCF-7, human lung carcinoma cell line A549, and human high-metastatic giant cell lung carcinoma cell line PG was analyzed by Western blot. After transfection of herg gene, the cytotoxicity of doxorubicin, erythromycin （a HERG K^＋ channel blocker）, or doxorubicin in combination with erythromycin to cancer cells was analyzed by MTT- assay. Intracellular content of doxorubicin was observed under fluorescent microscope. RESULTS. HERG protein level was higher in HT-29,MCF-7, and PG cells than in A549 cells. A549 cells were more sensitive to doxorubicin than HT-29 cells. The 50% inhibitory concentration （IC50） of doxorubicin was obviously higher in herg-transfected A549 cells than in parent A549 cells. Erythromycin obviously suppressed the growth of HT-29 cells,and showed synergic cytotoxicity with doxorubicin to HT-29 cells. There is no difference in intracellular doxorubicin content among herg-transfected A549 cells, pCDNA3.1-transfected A549 cells, and parent A549 cells.CONCLUSIONS： HERG expression might negatively correlate with the chemosensitivity of tumor cells to doxorubicin. Erythromycin may act as a modulator, and has synergic effect with doxorubicin. HERG may serve as a molecular marker and modulating target for individualized cancer therapy.