title: GLI1 confers profound phenotypic changes upon LNCaP prostate cancer cells that include the acquisition of a hormone independent state.
abstract: The GLI (GLI1/GLI2) transcription factors have been implicated in the development and progression of prostate cancer although our understanding of how they actually contribute to the biology of these common tumours is limited. We observed that GLI reporter activity was higher in normal (PNT-2) and tumourigenic (DU145 and PC-3) androgen-independent cells compared to androgen-dependent LNCaP prostate cancer cells and, accordingly, GLI mRNA levels were also elevated. Ectopic expression of GLI1 or the constitutively active ΔNGLI2 mutant induced a distinct cobblestone-like morphology in LNCaP cells that, regarding the former, correlated with increased GLI2 as well as expression of the basal/stem-like markers CD44, β1-integrin, ΔNp63 and BMI1, and decreased expression of the luminal marker AR (androgen receptor). LNCaP-GLI1 cells were viable in the presence of the AR inhibitor bicalutamide and gene expression profiling revealed that the transcriptome of LNCaP-GLI1 cells was significantly closer to DU145 and PC-3 cells than to control LNCaP-pBP (empty vector) cells, as well as identifying LCN2/NGAL as a highly induced transcript which is associated with hormone independence in breast and prostate cancer. Functionally, LNCaP-GLI1 cells displayed greater clonal growth and were more invasive than control cells but they did not form colonies in soft agar or prostaspheres in suspension suggesting that they do not possess inherent stem cell properties. Moreover, targeted suppression of GLI1 or GLI2 with siRNA did not reverse the transformed phenotype of LNCaP-GLI1 cells nor did double GLI1/GLI2 knockdowns activate AR expression in DU145 or PC-3 cells. As such, early targeting of the GLI oncoproteins may hinder progression to a hormone independent state but a more detailed understanding of the mechanisms that maintain this phenotype is required to determine if their inhibition will enhance the efficacy of anti-hormonal therapy through the induction of a luminal phenotype and increased dependency upon AR function.
authors.affiliation: Centre for Cutaneous Research, Blizard Institute of Cell and Molecular Science, Barts and the London School of Medicine and Dentistry, Queen Mary University of London, London, United Kingdom.
authors.forename: Sandeep K
authors.initials: SK
authors.lastname: Nadendla
authors.forename: Allon
authors.initials: A
authors.lastname: Hazan
authors.forename: Matt
authors.initials: M
authors.lastname: Ward
authors.forename: Lisa J
authors.initials: LJ
authors.lastname: Harper
authors.forename: Karwan
authors.initials: K
authors.lastname: Moutasim
authors.forename: Lucia S
authors.initials: LS
authors.lastname: Bianchi
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Naase
authors.forename: Lucy
authors.initials: L
authors.lastname: Ghali
authors.forename: Gareth J
authors.initials: GJ
authors.lastname: Thomas
authors.forename: David M
authors.initials: DM
authors.lastname: Prowse
authors.forename: Michael P
authors.initials: MP
authors.lastname: Philpott
authors.forename: Graham W
authors.initials: GW
authors.lastname: Neill
mesh_terms: D000728:Androgens / Q000378:metabolism; D015153:Blotting, Western; D002448:Cell Adhesion; D002460:Cell Line; D045744:Cell Line, Tumor; D049109:Cell Proliferation; D048430:Cell Shape; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008156:Luciferases / Q000235:genetics / Q000378:metabolism; D008297:Male; D020411:Oligonucleotide Array Sequence Analysis; D011471:Prostatic Neoplasms / Q000235:genetics / Q000378:metabolism / Q000473:pathology; D034622:RNA Interference; D011944:Receptors, Androgen / Q000235:genetics* / Q000378:metabolism; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014157:Transcription Factors / Q000235:genetics* / Q000378:metabolism; D000071676:Zinc Finger Protein GLI1
chemical_list: D000728:Androgens; C400551:GLI1 protein, human; D011944:Receptors, Androgen; D014157:Transcription Factors; D000071676:Zinc Finger Protein GLI1; D008156:Luciferases