title: Hypoxic induction of AKAP12 variant 2 shifts PKA-mediated protein phosphorylation to enhance migration and metastasis of melanoma cells.
abstract: Scaffold proteins are critical hubs within cells that have the ability to modulate upstream signaling molecules and their downstream effectors to fine-tune biological responses. Although they can serve as focal points for association of signaling molecules and downstream pathways that regulate tumorigenesis, little is known about how the tumor microenvironment affects the expression and activity of scaffold proteins. This study demonstrates that hypoxia, a common element of solid tumors harboring low oxygen levels, regulates expression of a specific variant of the scaffold protein AKAP12 (A-kinase anchor protein 12), AKAP12v2, in metastatic melanoma. In turn, through a kinome-wide phosphoproteomic and MS study, we demonstrate that this scaffolding protein regulates a shift in protein kinase A (PKA)-mediated phosphorylation events under hypoxia, causing alterations in tumor cell invasion and migration in vitro, as well as metastasis in an in vivo orthotopic model of melanoma. Mechanistically, the shift in AKAP12-dependent PKA-mediated phosphorylations under hypoxia is due to changes in AKAP12 localization vs. structural differences between its two variants. Importantly, our work defines a mechanism through which a scaffold protein can be regulated by the tumor microenvironment and further explains how a tumor cell can coordinate many critical signaling pathways that are essential for tumor growth through one individual scaffolding protein.
authors: Department of Radiation Oncology, Stanford University, Stanford, CA 94305;
authors: Elizabeth C
authors: EC
authors: Finger
authors: Department of Radiation Oncology, Stanford University, Stanford, CA 94305;
authors: Laura
authors: L
authors: Castellini
authors: Department of Radiation Oncology, Stanford University, Stanford, CA 94305;
authors: Erinn B
authors: EB
authors: Rankin
authors: Department of Radiation Oncology, Stanford University, Stanford, CA 94305;
authors: Marta
authors: M
authors: Vilalta
authors: Department of Obstetrics and Gynecology, University of Kansas Medical Center, Kansas City, KS 66160; and.
authors: Adam J
authors: AJ
authors: Krieg
authors: Department of Radiation Oncology, Stanford University, Stanford, CA 94305;
authors: Dadi
authors: D
authors: Jiang
authors: Department of Radiation Oncology, Stanford University, Stanford, CA 94305;
authors: Alice
authors: A
authors: Banh
authors: Department of Radiation Medicine, Knight Cancer Institute, Oregon Health and Science University, Portland, OR 97239.
authors: Wayne
authors: W
authors: Zundel
authors: Department of Radiation Oncology, Stanford University, Stanford, CA 94305;
authors: Marianne Broome
authors: MB
authors: Powell
authors: Department of Radiation Oncology, Stanford University, Stanford, CA 94305; giaccia@stanford.edu.
authors: Amato J
authors: AJ
authors: Giaccia
mesh_terms: D054758:A Kinase Anchor Proteins / Q000235:genetics / Q000378:metabolism*; D000595:Amino Acid Sequence; D000818:Animals; D018797:Cell Cycle Proteins / Q000235:genetics / Q000378:metabolism*; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D002465:Cell Movement; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism*; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008545:Melanoma / Q000378:metabolism / Q000473:pathology*; D051379:Mice; D008969:Molecular Sequence Data; D009361:Neoplasm Invasiveness; D009362:Neoplasm Metastasis; D009368:Neoplasm Transplantation; D010100:Oxygen / Q000378:metabolism; D010750:Phosphoproteins / Q000378:metabolism; D010766:Phosphorylation; D040901:Proteomics; D015398:Signal Transduction; D012878:Skin Neoplasms / Q000378:metabolism*
chemical_list: D054758:A Kinase Anchor Proteins; C491162:AKAP12 protein, human; D018797:Cell Cycle Proteins; D010750:Phosphoproteins; D017868:Cyclic AMP-Dependent Protein Kinases; D010100:Oxygen
keywords: AKAP12; melanoma; metastasis