ATP11B mediates platinum resistance in ovarian cancer
Myrthala Moreno-Smith, … , Gabriel Lopez-Berestein, Anil K. Sood
Myrthala Moreno-Smith, … , Gabriel Lopez-Berestein, Anil K. Sood
Published April 15, 2013
Citation Information: J Clin Invest. 2013;123(5):2119-2130. https://doi.org/10.1172/JCI65425.
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Research Article

ATP11B mediates platinum resistance in ovarian cancer

Abstract

Platinum compounds display clinical activity against a wide variety of solid tumors; however, resistance to these agents is a major limitation in cancer therapy. Reduced platinum uptake and increased platinum export are examples of resistance mechanisms that limit the extent of DNA damage. Here, we report the discovery and characterization of the role of ATP11B, a P-type ATPase membrane protein, in cisplatin resistance. We found that ATP11B expression was correlated with higher tumor grade in human ovarian cancer samples and with cisplatin resistance in human ovarian cancer cell lines. ATP11B gene silencing restored the sensitivity of ovarian cancer cell lines to cisplatin in vitro. Combined therapy of cisplatin and ATP11B-targeted siRNA significantly decreased cancer growth in mice bearing ovarian tumors derived from cisplatin-sensitive and -resistant cells. In vitro mechanistic studies on cellular platinum content and cisplatin efflux kinetics indicated that ATP11B enhances the export of cisplatin from cells. The colocalization of ATP11B with fluorescent cisplatin and with vesicular trafficking proteins, such as syntaxin-6 (STX6) and vesicular-associated membrane protein 4 (VAMP4), strongly suggests that ATP11B contributes to secretory vesicular transport of cisplatin from Golgi to plasma membrane. In conclusion, inhibition of ATP11B expression could serve as a therapeutic strategy to overcome cisplatin resistance.

Authors

Myrthala Moreno-Smith, J.B. Halder, Paul S. Meltzer, Tamas A. Gonda, Lingegowda S. Mangala, Rajesha Rupaimoole, Chunhua Lu, Archana S. Nagaraja, Kshipra M. Gharpure, Yu Kang, Cristian Rodriguez-Aguayo, Pablo E. Vivas-Mejia, Behrouz Zand, Rosemarie Schmandt, Hua Wang, Robert R. Langley, Nicholas B. Jennings, Cristina Ivan, Jeremy E. Coffin, Guillermo N. Armaiz, Justin Bottsford-Miller, Sang Bae Kim, Margaret S. Halleck, Mary J.C. Hendrix, William Bornman, Menashe Bar-Eli, Ju-Seog Lee, Zahid H. Siddik, Gabriel Lopez-Berestein, Anil K. Sood

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Figure 6

ATP11B, STX6, and VAMP4 contribute to cisplatin export.

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ATP11B, STX6, and VAMP4 contribute to cisplatin export. (A) Coimmunoprec...
(A) Coimmunoprecipitation of ATP11B with STX6 or VAMP4 in A2780-PAR and A2780-CP20 cell lysates. All coimmunoprecipitation lanes were run on the same gel but were noncontiguous. Input lanes (1:10 of original cell lysate) were run on a second gel simultaneously and detected with anti-ATP11B. Association of ATP11B with STX6 or VAMP4 was stronger in the presence of 0.5 μM cisplatin. Densitometry analysis of ATP11B protein was performed with ImageJ software. Data were normalized to a loading control (β-actin from original lysate) and are representative of 2 independent experiments. (B) Time course of cisplatin efflux in STX6- or VAMP4-silenced A2780-PAR cells and (C) STX6- or VAMP4-downregulated A2780-CP20 cells. Silencing of STX6 in A2780-CP20 cells resulted in significantly increased cellular platinum contents after 10 to 30 minutes of incubation without cisplatin (*P < 0.05). (D) Time kinetics of cisplatin efflux in ATP11B-upregulated STX6- or VAMP4-downregulated A2780-PAR cells and (E) in ATP11B-upregulated STX6- or VAMP4-silenced A2780-CP20 cells. Percentages of remaining cellular platinum were significantly increased in ATP11B-upregulated VAMP4-silenced A2780-PAR cells at all time points compared with those in A2780-PAR ATP11B-upregulated cells. In contrast, in ATP11B-upregulated A2780-CP20 cells, downregulation of STX6 led to increased platinum contents at all time points compared with those of ATP11B-upregulated A2780-CP20 cells. Data represent the mean ± SEM. *P < 0.05.