Volume 38, Issue 12 pp. 2248-2259
CANCER

Serine/threonine protein phosphatase 5 is a potential therapeutic target in cholangiocarcinoma

Ming-Hung Hu

Ming-Hung Hu

Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan

Division of Hematology and Oncology, Department of Medicine, Cardinal Tien Hospital, New Taipei City, Taiwan

School of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan

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Tzu-Ting Huang

Tzu-Ting Huang

Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei City, Taiwan

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Tzu-I Chao

Tzu-I Chao

Transplant Medicine & Surgery Research Centre, Changhua Christian Hospital, Changhua, Taiwan

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Li-Ju Chen

Li-Ju Chen

Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan

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Yen-Lin Chen

Yen-Lin Chen

Department of Pathology, Cardinal Tien Hospital, New Taipei City, Taiwan

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Ming-Hsien Tsai

Ming-Hsien Tsai

Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan

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Chun-Yu Liu

Corresponding Author

Chun-Yu Liu

Division of Medical Oncology, Department of Oncology, Taipei Veterans General Hospital, Taipei City, Taiwan

School of Medicine, National Yang-Ming University, Taipei, Taiwan

Division of Transfusion Medicine, Department of Medicine, Taipei Veterans General Hospital, Taipei, Taiwan

Correspondence

Kuen-Feng Chen, Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan.

Email: [email protected]

and

Jia-Horng Kao, Division of Gastroenterology and Hepatology, National Taiwan University Hospital, Taipei, Taiwan.

Email: [email protected]

and

Chun-Yu Liu, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan.

Email: [email protected]

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Jia-Horng Kao

Corresponding Author

Jia-Horng Kao

Graduate Institute of Clinical Medicine, College of Medicine, National Taiwan University, Taipei, Taiwan

Division of Gastroenterology and Hepatology, Department of Internal Medicine, National Taiwan University Hospital, Taipei, Taiwan

Correspondence

Kuen-Feng Chen, Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan.

Email: [email protected]

and

Jia-Horng Kao, Division of Gastroenterology and Hepatology, National Taiwan University Hospital, Taipei, Taiwan.

Email: [email protected]

and

Chun-Yu Liu, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan.

Email: [email protected]

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Kuen-Feng Chen

Corresponding Author

Kuen-Feng Chen

Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan

National Center of Excellence for Clinical Trial and Research, National Taiwan University Hospital, Taipei, Taiwan

Correspondence

Kuen-Feng Chen, Department of Medical Research, National Taiwan University Hospital, Taipei, Taiwan.

Email: [email protected]

and

Jia-Horng Kao, Division of Gastroenterology and Hepatology, National Taiwan University Hospital, Taipei, Taiwan.

Email: [email protected]

and

Chun-Yu Liu, Department of Oncology, Taipei Veterans General Hospital, Taipei, Taiwan.

Email: [email protected]

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First published: 24 May 2018
Citations: 8

Funding information

This study was supported by a grant from Cardinal Tien Hospital (CTH-104-2-2A02).

Handling Editor: Carmen Berasain

Abstract

Background & Aims

Few molecules are currently verified to be actionable drug targets in cholangiocarcinoma (CCA). Serine/threonine protein phosphatase 5 (PP5) dysregulation is related to several malignancies. However, the role of PP5 in CCA is poorly defined.

Methods

Colony and tumorsphere formation assays were conducted to establish the role of PP5 in CCA tumorigenesis. Cantharidin (CTD) and norcantharidin (NCTD), both potent PP5 inhibitors, were used in in vitro and in vivo experiments to validate the potential therapeutic role of PP5.

Results

Increased cell growth, colony formation and tumorsphere formation were observed in PP5-overexpressing CCA cells, whereas PP5 knockdown by shRNA decreased cell growth and colony formation. Tumours from HuCCT1 xenograft-bearing mice treated with PP5-shRNA showed decreased growth and increased AMP-activated protein kinase (AMPK) phosphorylation. Furthermore, CTD treatment decreased cell viability, reduced PP5 activity and enhanced AMPK phosphorylation in CCA cell lines. Overexpressing PP5 or enhancing PP5 activity suppressed AMPK phosphorylation and decreased CTD-induced cell death. Suppressing p-AMPK with siRNA or inhibitors also decreased CTD-induced cell death, suggesting a pivotal role for PP5-AMPK cascades in CCA. Immunoprecipitation revealed that PP5 interacted with AMPK. Importantly, treatment of HuCCT1 xenograft-bearing mice with NCTD, a CTD analogue with a lower systemic toxicity in vivo, suppressed PP5 activity, increased p-AMPK and reduced tumour volume.

Conclusions

Protein phosphatase 5 negatively regulates AMPK phosphorylation and contributes to CCA aggressiveness; thus, PP5 may be a potential therapeutic target in CCA.

CONFLICT OF INTEREST

All authors do not have any disclosures to report.

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