Balawant Kumar1, Rizwan Ahmad1, Giovanna A Giannico2, Roy Zent3, Geoffrey A Talmon4, Raymond C Harris3, Peter E Clark5, Vinata Lokeshwar6, Punita Dhawan1,7,8, Amar B Singh9,10,11. 1. Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, 985870 Nebraska Medical Center, Omaha, NE, 68198-5870, USA. 2. Department of Pathology, Microbiology and Immunology, Vanderbilt Medical Center, Nashville, TN, USA. 3. Department of Medicine, Vanderbilt Medical Center, Nashville, TN, USA. 4. Department of Pathology and Microbiology, University of Nebraska Medical Center, Omaha, NE, 68198, USA. 5. Levine Cancer Institute, Charlotte, NC, USA. 6. Department of Biochemistry and Molecular Biology, Augusta University, Augusta, GA, USA. 7. Member, Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, 985870 Nebraska Medical Center, Omaha, NE, 68198-5870, USA. 8. VA Nebraska-Western Iowa Health Care System, Omaha, NE, USA. 9. Department of Biochemistry and Molecular Biology, University of Nebraska Medical Center, 985870 Nebraska Medical Center, Omaha, NE, 68198-5870, USA. amar.singh@unmc.edu. 10. Member, Fred and Pamela Buffett Cancer Center, University of Nebraska Medical Center, 985870 Nebraska Medical Center, Omaha, NE, 68198-5870, USA. amar.singh@unmc.edu. 11. VA Nebraska-Western Iowa Health Care System, Omaha, NE, USA. amar.singh@unmc.edu.
Abstract
BACKGROUND: Claudin-2 expression is upregulated in multiple cancers and promotes cancer malignancy. Remarkably, the regulation of claudin-2 expression in kidney cell lines contrasts its reported regulation in other organs. However, claudin-2 role in renal clear cell carcinoma (RCC) remains unknown despite its predominant expression in the proximal tubular epithelium (PTE), the site of RCC origin. METHODS: Publicly available and independent patient databases were examined for claudin-2 association with RCC. The novel protein function was validated in vitro and in vivo by gain or loss of function assays. Mechanistic results were concluded by Mass spectroscopy, immunoprecipitation and mutational studies, and functional evaluations. RESULTS: We show that the significant decrease in claudin-2 expression characterized PTE cells and Ex-vivo cultured mouse kidney subjected to dedifferentiation. Inhibition of claudin-2 was enough to induce mesenchymal plasticity and invasive mobility in these models. Further, a progressive loss of claudin-2 expression associated with the RCC progression and poor patient survival. Overexpression of claudin-2 in RCC-derived cancer cells inhibited tumorigenic abilities and xenograft tumor growth. These data supported a novel tumor-suppressive role of claudin-2 in RCC. Mechanistic insights further revealed that claudin-2 associates with YAP-protein and modulates its phosphorylation (S127) and nuclear expression. The tumor suppressive effects of claudin-2 expression were lost upon deletion of its PDZ-binding motif emphasizing the critical role of the PDZ-domain in claudin-2 interaction with YAP in regulating RCC malignancy. CONCLUSIONS: Our results demonstrate a novel kidney specific tumor suppressive role for claudin-2 protein and further demonstrate that claudin-2 co-operates with the YAP signaling in regulating the RCC malignancy.
BACKGROUND: Claudin-2 expression is upregulated in multiple cancers and promotes cancer malignancy. Remarkably, the regulation of claudin-2 expression in kidney cell lines contrasts its reported regulation in other organs. However, claudin-2 role in renal clear cell carcinoma (RCC) remains unknown despite its predominant expression in the proximal tubular epithelium (PTE), the site of RCC origin. METHODS: Publicly available and independent patient databases were examined for claudin-2 association with RCC. The novel protein function was validated in vitro and in vivo by gain or loss of function assays. Mechanistic results were concluded by Mass spectroscopy, immunoprecipitation and mutational studies, and functional evaluations. RESULTS: We show that the significant decrease in claudin-2 expression characterized PTE cells and Ex-vivo cultured mouse kidney subjected to dedifferentiation. Inhibition of claudin-2 was enough to induce mesenchymal plasticity and invasive mobility in these models. Further, a progressive loss of claudin-2 expression associated with the RCC progression and poor patient survival. Overexpression of claudin-2 in RCC-derived cancer cells inhibited tumorigenic abilities and xenograft tumor growth. These data supported a novel tumor-suppressive role of claudin-2 in RCC. Mechanistic insights further revealed that claudin-2 associates with YAP-protein and modulates its phosphorylation (S127) and nuclear expression. The tumor suppressive effects of claudin-2 expression were lost upon deletion of its PDZ-binding motif emphasizing the critical role of the PDZ-domain in claudin-2 interaction with YAP in regulating RCC malignancy. CONCLUSIONS: Our results demonstrate a novel kidney specific tumor suppressive role for claudin-2 protein and further demonstrate that claudin-2 co-operates with the YAP signaling in regulating the RCC malignancy.
Entities:
Keywords:
De-differentiation; Hippo/yap signaling; Proliferation; Renal Cancer
Authors: Punita Dhawan; Amar B Singh; Natasha G Deane; Yiran No; Sheng-Ru Shiou; Carl Schmidt; John Neff; M Kay Washington; R Daniel Beauchamp Journal: J Clin Invest Date: 2005-06-16 Impact factor: 14.808