title: Identification of DNA-PKcs as a primary resistance factor of salinomycin in osteosarcoma cells.
abstract: Malignant osteosarcoma (OS) is still a deadly disease for many affected patients. The search for the novel anti-OS agent is extremely urgent and important. Our previous study has proposed that salinomycin is a novel anti-OS agent. Here we characterized DNA-dependent protein kinase catalytic subunit (DNA-PKcs) as a primary salinomycin resistance factor in OS cells. DNA-PKcs inhibitors (NU7026, NU7441 and LY294002) or DNA-PKcs shRNA knockdown dramatically potentiated salinomycin-induced death and apoptosis of OS cells (U2OS and MG-63 lines). Further, forced-expression of microRNA-101 ("miR-101") downregulated DNA-PKcs and augmented salinomycin's cytotoxicity against OS cells. Reversely, over-expression of DNA-PKcs in OS cells inhibited salinomycin's lethality. For the mechanism study, we show that DNA-PKcs is required for salinomycin-induced pro-survival autophagy activation. DNA-PKcs inhibition (by NU7441), shRNA knockdown or miR-101 expression inhibited salinomycin-induced Beclin-1 expression and autophagy induction. Meanwhile, knockdown of Beclin-1 by shRNA significantly sensitized salinomycin-induced OS cell lethality. In vivo, salinomycin administration suppressed U2OS xenograft tumor growth in severe combined immuno-deficient (SCID) mice, and its anti-tumor activity was dramatically potentiated with co-administration of the DNA-PKcs inhibitor NU7026. Together, these results suggest that DNA-PKcs could be a primary resistance factor of salinomycin in OS cells. DNA-PKcs inhibition or silence may thus significantly increase salinomycin's sensitivity in OS cells.
authors.affiliation: The Center of Diagnosis and Treatment for Children's Bone Diseases, The Children's Hospital Affiliated to Soochow University, Suzhou, China.
authors.forename: Yun-Fang
authors.initials: YF
authors.lastname: Zhen
authors.affiliation: The Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China.
authors.forename: Song-Tao
authors.initials: ST
authors.lastname: Li
authors.affiliation: Department of Orthopedics, The Affiliated Jiangyin Hospital of Medical College of Southeast University, Jiangyin, China.
authors.forename: Yun-Rong
authors.initials: YR
authors.lastname: Zhu
authors.affiliation: The Center of Diagnosis and Treatment for Children's Bone Diseases, The Children's Hospital Affiliated to Soochow University, Suzhou, China.
authors.forename: Xiao-Dong
authors.initials: XD
authors.lastname: Wang
authors.affiliation: The Department of Orthopedics, The Second Affiliated Hospital of Soochow University, Suzhou, China.
authors.forename: Xiao-Zhong
authors.initials: XZ
authors.lastname: Zhou
authors.affiliation: The Center of Diagnosis and Treatment for Children's Bone Diseases, The Children's Hospital Affiliated to Soochow University, Suzhou, China.
authors.forename: Lun-Qing
authors.initials: LQ
authors.lastname: Zhu
mesh_terms: D000818:Animals; D000970:Antineoplastic Agents / Q000008:administration & dosage / Q000494:pharmacology; D001859:Bone Neoplasms / Q000235:genetics / Q000378:metabolism*; D045744:Cell Line, Tumor; D049109:Cell Proliferation / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D002867:Chromones / Q000008:administration & dosage* / Q000494:pharmacology; D051747:DNA-Activated Protein Kinase / Q000235:genetics* / Q000378:metabolism; D019008:Drug Resistance, Neoplasm / Q000187:drug effects; D004357:Drug Synergism; D006801:Humans; D051379:Mice; D035683:MicroRNAs / Q000235:genetics; D009025:Morpholines / Q000008:administration & dosage* / Q000494:pharmacology; D009368:Neoplasm Transplantation; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D012516:Osteosarcoma / Q000235:genetics / Q000378:metabolism*; D011714:Pyrans / Q000008:administration & dosage* / Q000494:pharmacology; D000095662:Polyether Polyketides
chemical_list: D000970:Antineoplastic Agents; D002867:Chromones; D051747:DNA-Activated Protein Kinase; D035683:MicroRNAs; D009025:Morpholines; D009687:Nuclear Proteins; D011714:Pyrans; C479235:2-(morpholin-4-yl)benzo(h)chromen-4-one; C534072:MIRN101 microRNA, human; C010327:salinomycin; D000095662:Polyether Polyketides; C497263:PRKDC protein, human
keywords: DNA-PKcs; autophagy; microRNA-101; osteosarcoma (OS); salinomycin