title: Clinical aggressiveness of myxofibrosarcomas associates with down-regulation of p12CDK2AP1: prognostic implication of a putative tumor suppressor that induces cell cycle arrest and apoptosis via mitochondrial pathway.
abstract: BACKGROUND
  Attenuated endogenous protein levels of cyclin-dependent kinase 2 associated protein 1 (p12(CDK2AP1)) and its active homodimer p25(CDK2AP1) were found in myxofibrosarcoma-derived cell lines. Clinical and biological significances of this putative tumor suppressor in myxofibrosarcoma were studied.
  
  
  METHODS
  Plasmids carrying the CDK2AP1 gene and small hairpin RNA interference (shRNAi) targeting CDK2AP1 were transfected into NMFH-1 and/or OH931 cells to evaluate the effects on the CDK2, active caspase 3 (CASP3), cleaved-CASP8 and -CASP9 levels, cell cycle regulation, and/or apoptotic responses. Immunostaining of p12(CDK2AP1) was interpretable in 102 primary myxofibrosarcomas and correlated with clinicopathological variables, CDK2, Ki-67 and active CASP3 protein levels, and disease-specific survival.
  
  
  RESULTS
  Exogenous expression of p12(CDK2AP1) in NMFH-1 and OH931 cells significantly induced G0/G1 cell cycle arrest and down-regulated CDK2 protein level. In NMFH-1 cells, these aspects were reversed by shRNAi targeting CDK2AP1 gene. Increased active CASP3 and cleaved-CASP9, but not -CASP8, were detected after CDK2AP1 overexpression, suggesting the cellular apoptosis were induced through the mitochondrial pathway. Immunostains of p12(CDK2AP1) were aberrantly decreased in 56.9 % of cases; positively and negatively correlated with protein levels of CDK2 (p = 0.023), Ki-67 (p = 0.001) and active CASP3 (p < 0.001), respectively. Following by high histological grades, p12(CDK2AP1) down-regulation was predictive of worse disease-specific survival in univariate (p = 0.003) and multivariate (p = 0.004) analyses.
  
  
  CONCLUSIONS
  Through down-regulation of CDK2, high p12(CDK2AP1) level induced cell cycle arrest and the mitochondrial-dependent apoptotic pathway. Low p12(CDK2AP1) level represents a poor prognostic factor in patients with myxofibrosarcoma.
authors.affiliation: Department of Pathology, Chi Mei Medical Center, Tainan, Taiwan.
authors.forename: Chien-Feng
authors.initials: CF
authors.lastname: Li
authors.forename: Hsuan-Ying
authors.initials: HY
authors.lastname: Huang
authors.forename: Wen-Ren
authors.initials: WR
authors.lastname: Wu
authors.forename: Shih-Shin
authors.initials: SS
authors.lastname: Liang
authors.forename: Yi-Ling
authors.initials: YL
authors.lastname: Chen
authors.forename: Lih-Ren
authors.initials: LR
authors.lastname: Chen
authors.forename: Yu-Ting
authors.initials: YT
authors.lastname: Peng
authors.forename: Hui-Chieh
authors.initials: HC
authors.lastname: Lee
authors.forename: Yow-Ling
authors.initials: YL
authors.lastname: Shiue
mesh_terms: D017209:Apoptosis / Q000235:genetics; D053148:Caspase 3 / Q000032:analysis / Q000378:metabolism; D053181:Caspase 8 / Q000378:metabolism; D053453:Caspase 9 / Q000378:metabolism; D059447:Cell Cycle Checkpoints / Q000235:genetics; D045744:Cell Line, Tumor; D002470:Cell Survival; D000090266:Chromobox Protein Homolog 5; D051357:Cyclin-Dependent Kinase 2 / Q000032:analysis / Q000378:metabolism; D005260:Female; D005354:Fibrosarcoma / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics*; D006801:Humans; D019394:Ki-67 Antigen / Q000032:analysis; D008297:Male; D008875:Middle Aged; D008928:Mitochondria / Q000378:metabolism*; D008940:Mitotic Index; D009236:Myxosarcoma / Q000737:chemistry / Q000201:enzymology* / Q000235:genetics*; D010957:Plasmids; D012333:RNA, Messenger / Q000378:metabolism; D034741:RNA, Small Interfering / Q000235:genetics; D015996:Survival Rate; D014162:Transfection; D025521:Tumor Suppressor Proteins / Q000235:genetics*
chemical_list: C000715594:CBX5 protein, human; C096151:CDK2AP1 protein, human; D019394:Ki-67 Antigen; D012333:RNA, Messenger; D034741:RNA, Small Interfering; D025521:Tumor Suppressor Proteins; D000090266:Chromobox Protein Homolog 5; D051357:Cyclin-Dependent Kinase 2; D053148:Caspase 3; D053181:Caspase 8; D053453:Caspase 9