title: KLF9, a transcription factor induced in flutamide-caused cell apoptosis, inhibits AKT activation and suppresses tumor growth of prostate cancer cells.
abstract: BACKGROUND
  Kruppel-like factors (KLFs) are involved in various biological processes; emerging studies have indicated that KLF9 plays a critical role in regulating tumorigenesis. The role of KLF9 in prostate cancer (PCa), however, has not yet been investigated.
  
  
  METHODS
  The expression of KLF members, AKT- and apoptosis-related proteins were analyzed by Western blot or qRT-PCR. Tet-On inducible KLF9 expression was established for the evaluation of the effects of KLF9 on cell proliferation, apoptosis, and xenograft tumor growth in nude mice. Cell cycle and apoptosis were determined by flow cytometry.
  
  
  RESULTS
  KLF9 was induced in a time-dependent manner in flutamide-caused apoptosis, and knockdown of KLF9 significantly decreased flutamide-induced growth inhibition and apoptosis in LNCaP cells. The levels of KLF9 were relatively lower in PCa cell lines, particularly in androgen-independent cell lines compared with those in nontumorous prostate epithelial cell lines. Overexpression of KLF9 dramatically suppressed cell proliferation and caused cell cycle arrest in the G2/M phase and cell apoptosis in the androgen-independent cell lines, PC3 and DU145. Intriguingly, KLF9 expression severely suppressed the activation of AKT and its downstream targets. AKT reactivation partially rescued the KLF9-mediated inhibitory effects on the proliferation of PCa cells. More importantly, we found that KLF9 overexpression efficiently inhibited the xenograft tumor growth of PCa cells.
  
  
  CONCLUSIONS
  These data collectively showing that KLF9 substantially inhibits AKT activation and abrogates tumor growth of PCa cells, suggest the potential of either genetic or pharmacological activation of KLF9 in the therapeutic treatment of castration-resistant PCa.
authors.affiliation: Department of Urology, The Fifth People's Hospital of Shanghai, Fudan University, Shanghai, P.R., China.
authors.forename: Pengliang
authors.initials: P
authors.lastname: Shen
authors.forename: Jiabin
authors.initials: J
authors.lastname: Sun
authors.forename: Guiqin
authors.initials: G
authors.lastname: Xu
authors.forename: Li
authors.initials: L
authors.lastname: Zhang
authors.forename: Zhaojuan
authors.initials: Z
authors.lastname: Yang
authors.forename: Suhua
authors.initials: S
authors.lastname: Xia
authors.forename: Yang
authors.initials: Y
authors.lastname: Wang
authors.forename: Yongzhong
authors.initials: Y
authors.lastname: Liu
authors.forename: Guowei
authors.initials: G
authors.lastname: Shi
mesh_terms: D000818:Animals; D017209:Apoptosis / Q000187:drug effects* / Q000502:physiology; D015153:Blotting, Western; D048708:Cell Growth Processes / Q000187:drug effects / Q000502:physiology; D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects; D005434:Flow Cytometry; D005485:Flutamide / Q000494:pharmacology*; D064593:Heterografts; D006801:Humans; D020287:In Situ Nick-End Labeling; D053208:Kaplan-Meier Estimate; D051741:Kruppel-Like Transcription Factors / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C; D008819:Mice, Nude; D064129:Prostatic Neoplasms, Castration-Resistant / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D051057:Proto-Oncogene Proteins c-akt / Q000037:antagonists & inhibitors* / Q000235:genetics / Q000378:metabolism; D012334:RNA, Neoplasm / Q000737:chemistry / Q000235:genetics; D060888:Real-Time Polymerase Chain Reaction
chemical_list: C489676:KLF9 protein, human; D051741:Kruppel-Like Transcription Factors; D012334:RNA, Neoplasm; D005485:Flutamide; D051057:Proto-Oncogene Proteins c-akt
keywords: AKT; Kruppel-like factor 9; apoptosis; flutamide; prostate cancer