title: Hypoxia induces escape from innate immunity in cancer cells via increased expression of ADAM10: role of nitric oxide.
abstract: One key to malignant progression is the acquired ability of tumor cells to escape immune-mediated lysis. Whereas tumor hypoxia is known to play a causal role in cancer metastasis and resistance to therapy, the link between hypoxia and immune escape in cancer remains poorly understood. Here, we show that hypoxia induces tumor cell resistance to lysis mediated by immune effectors and that this resistance to lysis occurs via a hypoxia-inducible factor-1 (HIF-1)-dependent pathway linked to increased expression of the metalloproteinase ADAM10. This enzyme is required for the hypoxia-induced shedding of MHC class I chain-related molecule A (MICA), a ligand that triggers the cytolytic action of immune effectors, from the surface of tumor cells. Indeed, our findings show a mechanistic link between hypoxia-induced accumulation of the α-subunit of HIF-1 (HIF-1α), increased expression of ADAM10, and decreased surface MICA levels leading to tumor cell resistance to lysis mediated by innate immune effectors. Nitric oxide mimetic agents interfered with the hypoxia-induced accumulation of HIF-1α and with the hypoxia-induced upregulation of ADAM10 expression required for decreased surface MICA expression and resistance to lysis. Furthermore, treatment of tumor-bearing mice with nitroglycerin, a nitric oxide mimetic, attenuated tumor growth by a mechanism that relied upon innate immune effector cells. Together, these findings reveal a novel mechanism by which the hypoxic tumor microenvironment contributes to immune escape in cancer, lending support to potential immunotherapeutic strategies involving the use of nitric oxide mimetics.
authors: Department of Anatomy and Cell Biology, Queen's University, Kingston, Ontario, Canada.
authors: Ivraym B
authors: IB
authors: Barsoum
authors: Thomas K
authors: TK
authors: Hamilton
authors: Xin
authors: X
authors: Li
authors: Tiziana
authors: T
authors: Cotechini
authors: Ellen A
authors: EA
authors: Miles
authors: D Robert
authors: DR
authors: Siemens
authors: Charles H
authors: CH
authors: Graham
mesh_terms: D051722:ADAM Proteins / Q000235:genetics / Q000378:metabolism*; D000072197:ADAM10 Protein; D053829:Amyloid Precursor Protein Secretases / Q000235:genetics / Q000378:metabolism*; D000818:Animals; D015153:Blotting, Western; D015687:Cell Hypoxia; D045744:Cell Line, Tumor; D005434:Flow Cytometry; D015395:Histocompatibility Antigens Class I / Q000378:metabolism; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000235:genetics / Q000378:metabolism; D007113:Immunity, Innate; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D051379:Mice; D008819:Mice, Nude; D009369:Neoplasms / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D009374:Neoplasms, Experimental / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D009569:Nitric Oxide / Q000378:metabolism*; D005996:Nitroglycerin / Q000494:pharmacology; D034622:RNA Interference; D014183:Transplantation, Heterologous; D047368:Tumor Burden / Q000187:drug effects; D059016:Tumor Microenvironment / Q000187:drug effects / Q000235:genetics / Q000276:immunology; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D015395:Histocompatibility Antigens Class I; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; C099187:MHC class I-related chain A; D008565:Membrane Proteins; D014665:Vasodilator Agents; D009569:Nitric Oxide; D053829:Amyloid Precursor Protein Secretases; D051722:ADAM Proteins; D000072197:ADAM10 Protein; C491236:ADAM10 protein, human; D005996:Nitroglycerin