Phorbol ester-induced apoptosis is accompanied by NGFI-A and c-fos activation in androgen-sensitive prostate cancer cells.
We have previously demonstrated the induction of the early response transcription factor NGFI-A in castration-induced regression of the rat ventral prostate. We have developed an in vitro model to investigate the role of kinase signal transduction and early transcriptional regulation in apoptosis of androgen-sensitive prostate cells. Cell death was induced in the androgen-sensitive human prostate line, LNCaP, by addition of the protein kinase activator, 12-tetradecanoylphorbol 13-acetate (TPA). TPA-induced death of LNCaP cells was asynchronous and exhibited morphological and ultrastructural features indicative of apoptosis. Specifically, cytoplasmic contraction, condensation of nuclear chromatin, and formation of membrane-bound "apoptotic bodies" were observed. Additionally, the characteristic endonuclease-generated DNA ladder, commonly associated with apoptosis, was observed in TPA-treated LNCaP cultures. TPA-induced LNCaP apoptosis was preceded by rapid yet transient induction of the early response transcription factors NGFI-A and c-fos. In dose-response experiments, NGFI-A and c-fos gene activation parallels the induction of death in LNCaP cells. TPA-induced expression of NGFI-A and c-fos and death of LNCaP cultures were blocked by pretreatment with staurosporine, a potent inhibitor of several protein kinases. Based on these studies, we suggest that activation of a TPA-inducible kinase(s) mediates apoptosis of androgen-sensitive prostate cells by means of an intracellular pathway that may involve the transient activation of the early response transcription factors NGFI-A and c-fos.
Day
M L
ML
Division of Urology, Washington University School of Medicine, St. Louis, Missouri 63110.
Zhao
X
X
Wu
S
S
Swanson
P E
PE
Humphrey
P A
PA
D000470:Alkaloids / Q000494:pharmacology; D000728:Androgens; D017209:Apoptosis / Q000187:drug effects*; D002277:Carcinoma / Q000473:pathology*; D004249:DNA Damage; D004273:DNA, Neoplasm / Q000032:analysis; D004268:DNA-Binding Proteins / Q000378:metabolism*; D051766:Early Growth Response Protein 1; D004790:Enzyme Induction / Q000187:drug effects; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects*; D006801:Humans; D017874:Immediate-Early Proteins; D008297:Male; D009376:Neoplasms, Hormone-Dependent / Q000473:pathology*; D011471:Prostatic Neoplasms / Q000473:pathology*; D011494:Protein Kinases / Q000378:metabolism; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate / Q000494:pharmacology*; D014157:Transcription Factors / Q000378:metabolism*; D015533:Transcriptional Activation; D014407:Tumor Cells, Cultured
D000470:Alkaloids; D000728:Androgens; D004273:DNA, Neoplasm; D004268:DNA-Binding Proteins; C497325:EGR1 protein, human; D051766:Early Growth Response Protein 1; C486110:Egr1 protein, rat; D017874:Immediate-Early Proteins; D016760:Proto-Oncogene Proteins c-fos; D014157:Transcription Factors; D011494:Protein Kinases; D019311:Staurosporine; D013755:Tetradecanoylphorbol Acetate