title: Sunitinib deregulates tumor adaptation to hypoxia by inhibiting HIF-1alpha synthesis in HT-29 colon cancer cells.
abstract: Sunitinib (SU11248, Sutent) is a class III/V receptor tyrosine kinase (RTK) inhibitor that exhibits potent anti-angiogenic and anticancer activities. Preclinical studies demonstrated that the sunitinib effects are attributed to inhibition of VEGFR and PDGFR phosphorylation. However, even in colon cancer cells lacking sunitinib-targeted RTKs, sunitinib effectively inhibits tumor growth in a xenograft model, and this raises a question about the mechanism underlying the in vivo anticancer action of sunitinib. Since hypoxia is a critical microenvironment that tumors face, we addressed the possibility that sunitinib deregulates tumor adaptation to hypoxia. First we found that sunitinib limits the colony growth of HT-29, which is a colon adenocarcinoma cell line lacking the RTKs, and that HIF-1alpha in the colonies is decreased by sunitinib. In cultured HT-29 cells, sunitinib suppressed HIF-1alpha under hypoxic conditions. Moreover, sunitinib repressed the activity of HIF-1alpha and subsequently decreased the expressions of HIF-1 downstream genes. Mechanistically, sunitinib blocked the 5'-UTR-dependent translation of HIF-1alpha. The HIF-1alpha suppression by sunitinib was also reproduced in a VHL-null renal cell carcinoma cell line, where HIF-1alpha is not degradable. In conclusion, the sunitinib inhibition of HIF-1 signaling could restrain tumor progression in hypoxic regions, which may contribute to anticancer effect of sunitinib.
authors.affiliation: Department of Pharmacology, Seoul National University College of Medicine, 28 Yeongeon-dong, Jongno-gu, Seoul 110-799, Republic of Korea; Department of Biomedical sciences, Seoul National University College of Medicine, 28 Yeongeon-dong, Jongno-gu, Seoul 110-799, Republic of Korea.
authors.forename: Hyun-Woo
authors.initials: HW
authors.lastname: Shin
authors.forename: Chung-Hyun
authors.initials: CH
authors.lastname: Cho
authors.forename: Tae-You
authors.initials: TY
authors.lastname: Kim
authors.forename: Jong-Wan
authors.initials: JW
authors.lastname: Park
mesh_terms: D000970:Antineoplastic Agents / Q000494:pharmacology*; D015687:Cell Hypoxia / Q000187:drug effects; D019073:HT29 Cells; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit / Q000037:antagonists & inhibitors*; D007211:Indoles / Q000494:pharmacology*; D009369:Neoplasms / Q000378:metabolism*; D014176:Protein Biosynthesis; D047428:Protein Kinase Inhibitors / Q000494:pharmacology*; D011758:Pyrroles / Q000494:pharmacology*; D015398:Signal Transduction; D000077210:Sunitinib
chemical_list: D000970:Antineoplastic Agents; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D007211:Indoles; D047428:Protein Kinase Inhibitors; D011758:Pyrroles; D000077210:Sunitinib