Alterations in the expression of inhibitors of apoptosis during differentiation of prostate epithelial cells.
OBJECTIVE
To investigate alterations in the apoptotic phenotype, specifically the inhibitors of apoptosis (IAP) family, in prostate epithelial cells after differentiation from an apoptotic-resistant basal cell to an apoptotic-susceptible secretory cell.


METHODS
Cells of the immortalized human prostate epithelial line HPr-1AR were cultured with and with no 5alpha-dihydrotestosterone (DHT) to drive differentiation. Western blotting and reverse transcription-polymerase chain reaction (RT-PCR) were used to determine changes in differentiation markers such as cytokeratins (CK) 14 and 18, and in XIAP, cIAP-1 and cIAP-2. Flow cytometry was used to assess viability and apoptosis, by propidium iodide DNA staining of the cells during differentiation.


RESULTS
Morphological changes and the increased CK-18 and decreased CK-14 expression confirmed differentiation of cells towards a secretory phenotype. Real-time PCR and Western blotting confirmed the expression of the IAPs in the HPr-1AR cells. There was a time-dependent decrease in the mRNA expression of XIAP, cIAP-1 and cIAP-2 after treatment with DHT. Differentiation also resulted in decreased cIAP-1 and XIAP protein expression, but cIAP-2 remained unchanged. Spontaneous apoptosis was significantly increased during cellular differentiation.


CONCLUSIONS
We show for the first time that differentiation of HPr-1AR prostate epithelial cells results in the development of a transient end-stage cell that might be explained by the loss of the IAP family of proteins.
Long
Ronan M
RM
UCD School of Medicine and Medical Science, Conway Institute of Biomolecular and Biomedical Research, University College Dublin and Dublin Molecular Medicine Centre, Dublin, Ireland. ronanlong@hotmail.com
Morrissey
Colm
C
Walsh
Sinead
S
Hamilton
Hilary J
HJ
Farrell
Nicole
N
O'Neill
Amanda
A
Fitzpatrick
John M
JM
Watson
William R
WR
D017209:Apoptosis / Q000502:physiology*; D051017:Apoptosis Regulatory Proteins / Q000378:metabolism*; D000075747:Baculoviral IAP Repeat-Containing 3 Protein; D015153:Blotting, Western; D002454:Cell Differentiation / Q000502:physiology*; D004847:Epithelial Cells / Q000502:physiology*; D005434:Flow Cytometry; D006801:Humans; D051034:Inhibitor of Apoptosis Proteins / Q000378:metabolism; D053547:Keratin-14 / Q000378:metabolism; D053538:Keratin-18 / Q000378:metabolism; D008297:Male; D011467:Prostate / Q000166:cytology*; D011471:Prostatic Neoplasms / Q000473:pathology; D020133:Reverse Transcriptase Polymerase Chain Reaction; D044767:Ubiquitin-Protein Ligases; D051636:X-Linked Inhibitor of Apoptosis Protein / Q000378:metabolism
D051017:Apoptosis Regulatory Proteins; D051034:Inhibitor of Apoptosis Proteins; D053547:Keratin-14; D053538:Keratin-18; D051636:X-Linked Inhibitor of Apoptosis Protein; C494832:BIRC3 protein, human; D000075747:Baculoviral IAP Repeat-Containing 3 Protein; D044767:Ubiquitin-Protein Ligases