Ahmed Zunaid, Deyama Yoshiaki, Yoshimura Yoshitaka, Suzuki Kuniaki
Molecular Cell Pharmacology, Graduate School of Dental Medicine, Hokkaido University, Hokkaido, Japan.
Cancer Chemother Pharmacol. 2009 Mar;63(4):643-50. doi: 10.1007/s00280-008-0781-z. Epub 2008 Jun 11.
Cisplatin (CDDP) is one of the major chemotherapeutic drugs, but tumor cells' acquired resistance to CDDP limits its therapeutic potentials. One of the main reasons of resistance is reduced drug accumulation. The mechanism by which tumor cells accumulate reduced CDDP is not well elucidated yet. The aim of this study was to investigate what regulates intracellular CDDP accumulation.
Six different types of oral squamous carcinoma cells were used in this study. Assessment of CDDP sensitivity was determined by measuring the ATP level of the cells. Intracellular CDDP and copper (Cu) accumulation were measured and CDDP efflux study was conducted. Assessment of Na(+),K(+)-ATPase alpha and beta subunits, ATP7A and ATP7B was done by western blotting. Specific activities of Na(+),K(+)-ATPase and copper-transporting P-type ATPase (Cu(2+)-ATPase) were detected and a role of Na(+),K(+)-ATPase inhibitor in intracellular CDDP accumulation was examined.
Among the cells HSC-3 and BHY cells were found most CDDP-sensitive and CDDP-resistant, respectively. The most CDDP-sensitive HSC-3 cells exhibited an increased intracellular cisplatin accumulation, high Na(+),K(+)-ATPase activity and over-expressed Na(+),K(+)-ATPase alpha and beta subunits, ATP7A and ATP7B, compared to the most CDDP-resistant BHY cells, but there were no such differences between the two in the CDDP efflux level or Cu(2+)-ATPase activity. Moreover, pretreatment with Na(+),K(+)-ATPase inhibitor markedly reduced intracellular cisplatin accumulation.
Na(+),K(+)-ATPase activity is responsible for regulating intracellular CDDP accumulation in oral squamous carcinoma cells rather than Cu(2+)-ATPase.
顺铂（CDDP）是主要的化疗药物之一，但肿瘤细胞对CDDP获得性耐药限制了其治疗潜力。耐药的主要原因之一是药物蓄积减少。肿瘤细胞蓄积还原型CDDP的机制尚未完全阐明。本研究旨在探究调节细胞内CDDP蓄积的因素。
本研究使用了六种不同类型的口腔鳞状癌细胞。通过测量细胞的ATP水平评估CDDP敏感性。测定细胞内CDDP和铜（Cu）的蓄积，并进行CDDP外排研究。通过蛋白质印迹法评估Na(+)、K(+)-ATP酶α和β亚基、ATP7A和ATP7B。检测Na(+)、K(+)-ATP酶和铜转运P型ATP酶（Cu(2+)-ATP酶）的比活性，并研究Na(+)、K(+)-ATP酶抑制剂在细胞内CDDP蓄积中的作用。
在这些细胞中，HSC-3和BHY细胞分别被发现对CDDP最敏感和最耐药。与对CDDP最耐药的BHY细胞相比，对CDDP最敏感的HSC-3细胞表现出细胞内顺铂蓄积增加、Na(+)、K(+)-ATP酶活性高以及Na(+)、K(+)-ATP酶α和β亚基、ATP7A和ATP7B过度表达，但两者在CDDP外排水平或Cu(2+)-ATP酶活性方面没有此类差异。此外，用Na(+)、K(+)-ATP酶抑制剂预处理可显著降低细胞内顺铂蓄积。
Na(+)、K(+)-ATP酶活性负责调节口腔鳞状癌细胞内的CDDP蓄积，而非Cu(2+)-ATP酶。
