1. p85β regulates autophagic degradation of AXL to activate oncogenic signaling
- Author
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Lydia W.T. Cheung, Yiling Lu, Rakesh Sharma, Gordon B. Mills, George L. Tipoe, Chloe C. Y. Fung, Xinran Li, Dong Zhang, Victor Cy Mak, Ling Rao, Yuan Zhou, Chao Gu, and Annie N.Y. Cheung
- Subjects
0301 basic medicine ,Carcinogenesis ,General Physics and Astronomy ,Cell Cycle Proteins ,medicine.disease_cause ,Receptor tyrosine kinase ,0302 clinical medicine ,Phosphorylation ,Nuclear protein ,lcsh:Science ,Cancer ,Ovarian Neoplasms ,Multidisciplinary ,biology ,Chemistry ,Nuclear Proteins ,Up-Regulation ,Ubiquitin ligase ,Cell biology ,Class Ia Phosphatidylinositol 3-Kinase ,030220 oncology & carcinogenesis ,Female ,Signal transduction ,Signal Transduction ,animal structures ,Science ,Disease-Free Survival ,Article ,General Biochemistry, Genetics and Molecular Biology ,03 medical and health sciences ,Enzyme activator ,Cell Line, Tumor ,Proto-Oncogene Proteins ,Autophagy ,medicine ,Humans ,Ubiquitination ,Membrane Transport Proteins ,Receptor Protein-Tyrosine Kinases ,General Chemistry ,Axl Receptor Tyrosine Kinase ,Enzyme Activation ,Gene Ontology ,030104 developmental biology ,Proteolysis ,biology.protein ,lcsh:Q ,Lysosomes ,Proto-Oncogene Proteins c-akt - Abstract
PIK3R2 encodes the p85β regulatory subunit of phosphatidylinositol 3-kinase and is frequently amplified in cancers. The signaling mechanism and therapeutic implication of p85β are poorly understood. Here we report that p85β upregulates the protein level of the receptor tyrosine kinase AXL to induce oncogenic signaling in ovarian cancer. p85β activates p110 activity and AKT-independent PDK1/SGK3 signaling to promote tumorigenic phenotypes, which are all abolished upon inhibition of AXL. At the molecular level, p85β alters the phosphorylation of TRIM2 (an E3 ligase) and optineurin (an autophagy receptor), which mediate the selective regulation of AXL by p85β, thereby disrupting the autophagic degradation of the AXL protein. Therapeutically, p85β expression renders ovarian cancer cells vulnerable to inhibitors of AXL, p110, or PDK1. Conversely, p85β-depleted cells are less sensitive to these inhibitors. Together, our findings provide a rationale for pharmacological blockade of the AXL signaling axis in PIK3R2-amplified ovarian cancer., p85β (PIK3R2), a regulatory subunit of PI3K, has oncogenic properties. Here the authors show that p85β promotes AXL protein stability, which in turn activates p110 to induce PDK1/SGK3 signaling, and therapeutically, p85β-expressing ovarian cancer cells are sensitive to AXL inhibition.
- Published
- 2020