title: Human chorionic gonadotropin modulates prostate cancer cell survival after irradiation or HMG CoA reductase inhibitor treatment.
abstract: The impact of human chorionic gonadotropin (hCG) on prostate carcinoma viability was investigated. Treatment of LNCaP and PC-3 cells with hCG modestly reduced cell viability within 96 h. Treatment of cells with hCG followed by exposure to ionizing radiation enhanced radiosensitivity. Exposure of LNCaP cells to hCG promoted activation of epidermal growth factor receptor (ERBB1) via a Galpha(i)-, mitogen-activated protein kinase kinase (MEK)1/2-, and metalloprotease-dependent paracrine mechanism, effects that were further enhanced after radiation exposure, and that were causal in prolonged intense activation of poly(ADP-ribose) polymerase (PARP). Inhibition of ERBB1, MEK1, or PARP1 function suppressed the radiosensitizing properties of hCG. Radiosensitization was also, in part, dependent upon c-Jun NH2-terminal kinase 1/2 signaling. PARP1-dependent radiosensitization was suppressed by a pan-caspase inhibitor and by knockdown of apoptosis-inducing factor expression. Inhibition of phosphatidylinositol 3-kinase, expression of dominant-negative AKT, or treatment with the HMG CoA reductase inhibitor lovastatin suppressed AKT phosphorylation and enhanced the cytotoxic effects of hCG. The enhancing effect of lovastatin was reproduced by incubation with a geranylgeranyl transferase inhibitor and blocked by coexposure to geranylgeranyl pyrophosphate. Treatment with hCG and lovastatin decreased expression of BCL-(XL) and XIAP, and increased expression of IkappaB. The cytotoxic effects of hCG were enhanced by expression of dominant-negative IkappaB, and they were abolished by coexpression of activated AKT. Expression of activated AKT maintained BCL-(XL) levels in cells expressing dominant-negative IkappaB. The promotion of hCG lethality by lovastatin was abolished by overexpression of BCL-(XL), and was dependent upon activation of caspase-9. Thus, hCG, in combination with radiation and lovastatin, may represent a novel approach to kill prostate cancer cells.
authors.affiliation: Department of Biochemistry, 401 College St., Massey Cancer Center, Room 2-108, Box 980035, Virginia Commonwealth University, Richmond VA 23298-0035, USA.
authors.forename: Adly
authors.initials: A
authors.lastname: Yacoub
authors.forename: William
authors.initials: W
authors.lastname: Hawkins
authors.forename: David
authors.initials: D
authors.lastname: Hanna
authors.forename: Hong
authors.initials: H
authors.lastname: Young
authors.forename: Margaret A
authors.initials: MA
authors.lastname: Park
authors.forename: Mark
authors.initials: M
authors.lastname: Grant
authors.forename: John D
authors.initials: JD
authors.lastname: Roberts
authors.forename: David T
authors.initials: DT
authors.lastname: Curiel
authors.forename: Paul B
authors.initials: PB
authors.lastname: Fisher
authors.forename: Kristoffer
authors.initials: K
authors.lastname: Valerie
authors.forename: Steven
authors.initials: S
authors.lastname: Grant
authors.forename: Michael P
authors.initials: MP
authors.lastname: Hagan
authors.forename: Paul
authors.initials: P
authors.lastname: Dent
mesh_terms: D045744:Cell Line, Tumor; D002470:Cell Survival / Q000187:drug effects* / Q000528:radiation effects; D006063:Chorionic Gonadotropin / Q000494:pharmacology*; D004791:Enzyme Inhibitors / Q000627:therapeutic use; D018773:Genes, erbB-1 / Q000187:drug effects; D006801:Humans; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors / Q000494:pharmacology*; D008297:Male; D011471:Prostatic Neoplasms / Q000188:drug therapy / Q000473:pathology* / Q000532:radiotherapy
chemical_list: D006063:Chorionic Gonadotropin; D004791:Enzyme Inhibitors; D019161:Hydroxymethylglutaryl-CoA Reductase Inhibitors