Objective To study the expression and function of PKC-α and βⅠ isoenzymes in drug-resistant cells of gastric cancer. Methods Two tumor cell lines were used in the study: gastric cancer SGC7901 and its drug-resistant counterpart SGC7901/VCR stepwise-selected by various concentrations of vincristine. The expression of PKC-α and βⅠ isoenzymes in SGC7901 and SGC7901/VCR was detected by immunohistochemistry, laser confocal scanning microscopy and Western blot. The effects of anti-PKC-α or βⅠ antibody on adriamycin accumulation in SGC7901/VCR cells were determined by flow cytometric analysis. Results SGC7901 cells exhibited positive staining of PKC-α. The staining of PKC-α in SGC7901/VCR was stronger than that in SGC7901 cells. The higher the concentrations of vincristine, the stronger staining of PKC-α was observed on SGC7901/VCR cells. Both SGC7901 and SGC7901/VCR cells were positive for PKC-βⅠ, but without difference in staining intensity. Comparing with SGC7901, SGC7901/VCR cells showed decreased adriamycin accumulation; the decrease was more marked with the increase in concentrations of vincristine for selection of cells. Increased adriamycin accumulation in SGC7901/VCR was observed when co-incubated with anti-PKC-α but not anti-PKC-βⅠantibodies. Conclusion PKC-α may play a role in multidrug resistance of gastric cancer cells SGC7901/VCR.%目的探讨蛋白激酶C（PKC）不同的同工酶亚型在胃癌细胞多药耐药中的作用。方法应用免疫组织化学、激光共聚焦显微镜及Western blot，观察传统型PKC（cPKCs）的PKC-α与PKC-βⅠ在胃癌细胞SGC7901及其不同剂量长春新碱（VCR 0.3，0.7，1.0 mg/L）诱导的耐药细胞SGC7901/VCR中的表达与分布；以阿霉素(ADM)为指示剂，通过流式细胞仪检测PKC-α与PKC-βⅠ的相应抗体对SGC7901/VCR细胞内药物蓄积浓度的影响。结果（1）PKC-α在SGC7901呈阳性表达；在SGC7901/VCR呈强阳性，其表达强度随耐药剂量的增加而呈增加趋势。（2）PKC-βⅠ在SGC7901及其不同耐药剂量的耐药细胞SGC7901/VCR中均呈弱阳性表达，相互之间差异无显著性。（3）以ADM为荧光指示剂，通过流式细胞仪检测显示，SGC7901/VCR细胞内药物浓度比SGC7901明显降低，并且随耐药剂量的增加而呈逐渐减少趋势；SGC7901/VCR与抗PKC-α抗体共同孵育后，其细胞内ADM蓄积增加，而与抗PKC-βⅠ抗体共同孵育后，其细胞内ADM浓度无明显变化。结论胃癌细胞SGC7901/VCR的耐药机制可能与PKC-α有关，而与PKC-βⅠ无明显相关性。
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