Small interfering RNA targeting the subunit ATP6L of proton pump V-ATPase overcomes chemoresistance of breast cancer cells

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• 作者：Haiyan You ; Jie Jin ; Huiqun Shu ; Bin Yu ; Angelo De Milito ; Francesco Lozupone ; Yun Deng ; Ning Tang ; Genfu Yao ; Stefano Fais ; Jianren Gu ; Wenxin Qin
• 关键词：ATP6L ; RNA interference ; Multidrug resistance ; Chemotherapy ; Breast cancer
• 刊名：Cancer Letters
• 出版年：2009
• 出版时间：18 July 2009
• 年：2009
• 卷：280
• 期：1
• 页码：110-119
• 全文大小：692 K

文摘

One of the mechanisms of multiple drug resistance (MDR) is inappropriate sequestration of basic chemotherapeutic agents in acidic endo-lysosomes of cells. The protonation, sequestration, and secretion (PSS) model indicates that drug distribution can be affected by intracellular pH such as lysosomal pH. The vacuolar-H⁺-ATPase (V-ATPase) plays an important role in regulation of intracellular pH by pumping protons into acidic endosomes via an ATP-driven process. In this study, ATP6L, the 16 kDa subunit of V-ATPase, was knocked-down by anti-ATP6L small interfering RNA (siRNA) to study the effect on chemosensitivity in the human drug-resistant breast cancer cells MCF-7/ADR. Introduction of anti-ATP6L small interfering RNA duplex into drug-resistant cancer cells significantly inhibited the expression of ATP6L mRNA and protein, as detected by qRT-PCR and Western blot. Inhibition of ATP6L expression by siRNA in MCF-7/ADR sensitized the cells to the cytotoxicity of basic chemotherapeutic agents like doxorobicin, 5-fluorourocil and vincristine. This effect was mediated by a significant increase in lysosomal pH and retention of anticancer drugs into nuclei of cells. These results support the role of tumor acidity in resistance to chemotherapy and provide a rationale for the use of tumor pH modifier agents as coadjuvants in novel anticancer therapies.