In Vivo Role of INPP4B in Tumor and Metastasis Suppression through Regulation of PI3K-AKT Signaling at Endosomes.

Abstract

The phosphatases PTEN and INPP4B have been proposed to act as tumor suppressors by antagonizing PI3K-AKT signaling and are frequently dysregulated in human cancer. Although PTEN has been extensively studied, little is known about the underlying mechanisms by which INPP4B exerts its tumor-suppressive function and its role in tumorigenesis in vivo. Here, we show that a partial or complete loss of Inpp4b morphs benign thyroid adenoma lesions in Pten heterozygous mice into lethal and metastatic follicular-like thyroid cancer (FTC). Importantly, analyses of human thyroid cancer cell lines and specimens reveal INPP4B downregulation in FTC. Mechanistically, we find that INPP4B, but not PTEN, is enriched in the early endosomes of thyroid cancer cells, where it selectively inhibits AKT2 activation and in turn tumor proliferation and anchorage-independent growth. We therefore identify INPP4B as a novel tumor suppressor in FTC oncogenesis and metastasis through localized regulation of the PI3K-AKT pathway at the endosomes.Although both PTEN and INPP4B can inhibit PI3K-AKT signaling through their lipid phosphatase activities, here we demonstrate lack of an epistatic relationship between the two tumor suppressors. Instead, the qualitative regulation of PI3K-AKT2 signaling by INPP4B provides a mechanism for their cooperation in suppressing thyroid tumorigenesis and metastasis.

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Published Version (Please cite this version)

10.1158/2159-8290.CD-14-1347

Publication Info

Li Chew, Chen, Andrea Lunardi, Federico Gulluni, Daniel T Ruan, Ming Chen, Leonardo Salmena, Michiya Nishino, Antonella Papa, et al. (2015). In Vivo Role of INPP4B in Tumor and Metastasis Suppression through Regulation of PI3K-AKT Signaling at Endosomes. Cancer discovery, 5(7). pp. 740–751. 10.1158/2159-8290.CD-14-1347 Retrieved from https://hdl.handle.net/10161/20381.

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Chen

Ming Chen

Associate Professor in Pathology

Our laboratory is interested in understanding the molecular and genetic events underlying cancer progression and metastasis. The focus of our work is a series of genetically engineered mouse models that faithfully recapitulate human disease. Using a combination of mouse genetics, omics technologies, cross-species analyses and in vitro approaches, we aim to identify cancer cell–intrinsic and –extrinsic mechanisms driving metastatic cancer progression, with a long–term goal of developing new therapeutic strategies for preventing and treating metastatic disease. 


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