- 作者: Tsung-Ming Chang, Pei-Yi Chu, Hui-You Lin, Kuo-Wei Huang, Wen-Chun Hung, Yan-Shen Shan, Li-Tzong Chen & Hui-Jen Tsai
- 作者服務機構: 1.Department of Internal Medicine, Kaohsiung Medical University Hospital, and Center for Cancer Research, Kaohsiung Medical University, Kaohsiung, Taiwan 2.Department of Internal Medicine, Kaohsiung Medical University Hospital, Kaohsiung Medical University, Kaohsiung, Taiwan 3.Department of Medical Laboratory Science, College of Medical Science and Technology, I-Shou University, Kaohsiung, Taiwan 4.Department of Oncology, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan 5.Department of Pathology, Show Chwan Memorial Hospital, Changhua, Taiwan 6.Department of Post-Baccalaureate Medicine, College of Medicine, National Chung Hsing University, Taichung, Taiwan 7.Department of Surgery, National Cheng Kung University Hospital, College of Medicine, National Cheng Kung University, Tainan, Taiwan 8.Institute of Clinical Medicine, College of Medicine, National Cheng Kung University, Tainan, Taiwan 9.National Institute of Cancer Research, National Health Research Institutes, 1F No 367, Sheng-Li Road, Tainan, 70456, Taiwan 10.School of Medicine, College of Medicine, Fu Jen Catholic University, New Taipei City, Taiwan
- 中文摘要:
- 英文摘要:
Background
Phosphatase and tensin homolog (PTEN) is a tumor suppressor. Low PTEN expression has been observed in pancreatic neuroendocrine tumors (pNETs) and is associated with increased liver metastasis and poor survival. Vascular endothelial growth factor receptor 3 (VEGFR3) is a receptor tyrosine kinase and is usually activated by binding with vascular endothelial growth factor C (VEGFC). VEGFR3 has been demonstrated with lymphangiogenesis and cancer invasiveness. PTEN is also a phosphatase to dephosphorylate both lipid and protein substrates and VEGFR3 is hypothesized to be a substrate of PTEN. Dual-specificity phosphatase 19 (DUSP19) is an atypical DUSP and can interact with VEGFR3. In this study, we investigated the function of PTEN on regulation of pNET invasiveness and its association with VEGFR3 and DUSP19.
Methods
PTEN was knocked down or overexpressed in pNET cells to evaluate its effect on invasiveness and its association with VEGFR3 phosphorylation. In vitro phosphatase assay was performed to identify the regulatory molecule on the regulation of VEGFR3 phosphorylation. In addition, immunoprecipitation, and immunofluorescence staining were performed to evaluate the molecule with direct interaction on VEGFR3 phosphorylation. The animal study was performed to validate the results of the in vitro study.
Results
The invasion and migration capabilities of pNETs were enhanced by PTEN knockdown accompanied with increased VEGFR3 phosphorylation, ERK phosphorylation, and increased expression of epithelial–mesenchymal transition molecules in the cells. The enhanced invasion and migration abilities of pNET cells with PTEN knockdown were suppressed by addition of the VEGFR3 inhibitor MAZ51, but not by the VEGFR3-Fc chimeric protein to neutralize VEGFC. VEGFR3 phosphorylation is responsible for pNET cell invasiveness and is VEGFC-independent. However, an in vitro phosphatase assay failed to show VEGFR3 as a substrate of PTEN. In contrast, DUSP19 was transcriptionally upregulated by PTEN and was shown to dephosphorylate VEGFR3 via direct interaction with VEGFR3 by an in vitro phosphatase assay, immunoprecipitation, and immunofluorescence staining. Increased tumor invasion into peripheral tissues was validated in xenograft mouse model. Tumor invasion was suppressed by treatment with VEGFR3 or MEK inhibitors.
Conclusions
PTEN regulates pNET invasiveness via DUSP19-mediated VEGFR3 dephosphorylation. VEGFR3 and DUSP19 are potential therapeutic targets for pNET treatment. - 中文關鍵字:
- 英文關鍵字: PTEN, VEGFR3, DUSP19, Pancreatic neuroendocrine tumor, Invasiveness