title: Antileukemic roles of human phospholipid scramblase 1 gene, evidence from inducible PLSCR1-expressing leukemic cells.
abstract: Phospholipid scramblase 1 (PLSCR1) is a multiply palmitoylated protein which is localized in either the cell membrane or nucleus depending on its palmitoylated state. The increasing evidence showed the biological roles of PLSCR1 in cell signaling, maturation and apoptosis. To investigate the functions of PLSCR1 in leukemic cells, we generated an inducible PLSCR1-expressing cell line using myeloid leukemic U937 cells. In this cell line, PLSCR1 was tightly regulated and induced upon tetracycline withdrawal. Our results showed that inducible PLSCR1 expression arrested the proliferation of U937 cells at G1 phase. Meanwhile, PLSCR1-overexpressing U937 cells also underwent granulocyte-like differentiation with increased sensitivity to etoposide-induced apoptosis. Furthermore, we also found that PLSCR1 induction increased cyclin-dependent kinase inhibitors p27(Kip1) and p21(Cip1) proteins, together with downregulation of S phase kinase-associated protein 2 (SKP2), an F-box subunit of the ubiquitin-ligase complex that targets proteins for degradation. Additionally, PLSCR1 induction significantly decreased c-Myc protein and antiapoptotic Bcl-2 protein. Although the exact mechanism by which PLSCR1 regulates these cellular events and gene expression remains unresolved, our results suggest that PLSCR1 plays the antagonistic role regarding leukemia development. These data will shed new insights into understanding the biochemical and biological functions of PLSCR1 protein.
authors.affiliation: Institute of Health Science, Shanghai Institutes for Biological Sciences and Graduate School of Chinese Academy of Sciences, Shanghai Jiao Tong University School of Medicine (SJTU-SM, formerly Shanghai Second Medical University), Shanghai, China.
authors.forename: Y
authors.initials: Y
authors.lastname: Huang
authors.forename: Q
authors.initials: Q
authors.lastname: Zhao
authors.forename: C-X
authors.initials: CX
authors.lastname: Zhou
authors.forename: Z-M
authors.initials: ZM
authors.lastname: Gu
authors.forename: D
authors.initials: D
authors.lastname: Li
authors.forename: H-Z
authors.initials: HZ
authors.lastname: Xu
authors.forename: T
authors.initials: T
authors.lastname: Wiedmer
authors.forename: P J
authors.initials: PJ
authors.lastname: Sims
authors.forename: K-W
authors.initials: KW
authors.lastname: Zhao
authors.forename: G-Q
authors.initials: GQ
authors.lastname: Chen
mesh_terms: D017209:Apoptosis / Q000187:drug effects / Q000235:genetics; D002453:Cell Cycle / Q000235:genetics; D002454:Cell Differentiation / Q000235:genetics; D002460:Cell Line; D049109:Cell Proliferation; D005047:Etoposide / Q000494:pharmacology; D016193:G1 Phase; D005786:Gene Expression Regulation; D015973:Gene Expression Regulation, Leukemic; D006801:Humans; D007938:Leukemia / Q000235:genetics* / Q000378:metabolism; D022423:Myeloid Cells; D049294:Phospholipid Transfer Proteins / Q000235:genetics / Q000378:metabolism / Q000502:physiology*; D014162:Transfection; D014407:Tumor Cells, Cultured; D020298:U937 Cells
chemical_list: C493422:PLSCR1 protein, human; D049294:Phospholipid Transfer Proteins; D005047:Etoposide