title: Dual mTORC1/2 inhibition by INK-128 results in antitumor activity in preclinical models of osteosarcoma.
abstract: Existing evidence has shown that mammalian target of rapamycin (mTOR) overactivation is an important contributor of osteosarcoma (OS) progression. Here, we studied the potential anti-OS activity of a potent mTOR kinase inhibitor: INK-128 (MLN0128). We demonstrated that INK-128 induced potent cytotoxic effects against several human OS cell lines (U2OS, MG-63 and SaOs-2), yet same INK-128 treatment was safe (non-cytotoxic) to OB-6 human osteoblastic cells and MLO-Y4 human osteocytic cells. INK-128 induced caspase-dependent apoptosis in OS cells, but not in MLO-Y4/OB-6 cells. The caspase-3 specific inhibitor (z-DVED-fmk) or the pan caspase inhibitor (z-VAD-fmk) dramatically attenuated INK-128-exerted cytotoxicity against OS cells. Molecularly, INK-128 inhibited activation of mTORC1 (S6K1 and S6 phosphorylations) and mTORC2 (AKT Ser-473 phosphorylation), without affecting AKT Thr-308 phosphorylation in U2OS cells. Significantly, AKT inhibition by MK-2206 (an AKT inhibitor), or AKT1/2 stable knockdown by targeted-shRNA, remarkably sensitized INK-128-induced activity in OS cells. In vivo, oral administration of INK-128 potently inhibited U2OS xenograft growth in severe combined immuno-deficient (SCID) mice. mTORC1/2 activation in xenograft tumors was also suppressed with INK-128 administration. In summary, we show that INK-128 exerts potent anti-OS activity in vitro and in vivo. INK-128 might be further investigated as a novel anti-OS agent.
authors.affiliation: Department of Intensive Medicine, The Quanzhou First Hospital Affiliated to Fujian Medical University, Quanzhou, 362000, China.
authors.forename: Haibin
authors.initials: H
authors.lastname: Jiang
authors.affiliation: Department of Orthopaedics, The Quanzhou First Hospital Affiliated to Fujian Medical University, Quanzhou, 362000, China. Electronic address: drzenggukevip@126.com.
authors.forename: Zhiyuan
authors.initials: Z
authors.lastname: Zeng
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000627:therapeutic use*; D017209:Apoptosis / Q000187:drug effects; D001583:Benzoxazoles / Q000627:therapeutic use*; D001859:Bone Neoplasms / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D001842:Bone and Bones / Q000187:drug effects / Q000378:metabolism / Q000473:pathology; D045744:Cell Line, Tumor; D005260:Female; D006801:Humans; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D051379:Mice; D016513:Mice, SCID; D046912:Multiprotein Complexes / Q000037:antagonists & inhibitors* / Q000378:metabolism; D012516:Osteosarcoma / Q000188:drug therapy* / Q000378:metabolism / Q000473:pathology; D011743:Pyrimidines / Q000627:therapeutic use*; D058570:TOR Serine-Threonine Kinases / Q000037:antagonists & inhibitors* / Q000378:metabolism; D000225:Adenine / Q000031:analogs & derivatives
chemical_list: D000970:Antineoplastic Agents; D001583:Benzoxazoles; D000076222:Mechanistic Target of Rapamycin Complex 1; D000076225:Mechanistic Target of Rapamycin Complex 2; D046912:Multiprotein Complexes; D011743:Pyrimidines; D058570:TOR Serine-Threonine Kinases; C572449:sapanisertib; D000225:Adenine
keywords: Apoptosis; INK-128; Osteosarcoma; mTORC1/2