Androgen receptor expression in androgen-independent prostate cancer cell lines.
BACKGROUND
Almost all attempts at establishing prostate carcinoma cell lines have resulted in generation of cells that are androgen-independent, including commonly used LNCaP which expresses androgen receptor (AR) and AR-negative Du145 and PC-3. We attempted to clarify the mechanism(s) responsible for the failure to respond to androgen.


METHODS
Cell lines LNCaP, CWR22R, PC-3, Du145, and CA7T2CL were used to examine the AR promoter function with a reporter gene assay and its methylation status by Southern blot, PCR of bisulfite-converted DNA, and 5-aza-2'-deoxycytidine treatment. Structural abnormalities of the AR were identified by sequencing of reverse-transcribed mRNA.


RESULTS
All tested AR-positive prostate carcinoma cells were capable of AR transcription at a significantly higher level than PC-3 and Du145, thus suggesting relative deficiency of the transcription factors in the AR-negative cells, further associated with methylation. Examination of CWR22R cells, which express the AR but are androgen-independent, identified an in-frame duplication of exon 3, which resulted in insertion of 39 amino acids in the DNA-binding domain.


CONCLUSIONS
Relative deficiency of transcription factors associated with methylation is responsible for the lack of AR promoter function in most of AR-negative cell lines. Mutations in the AR gene are present in the cells that express the AR but are androgen-independent.
Chlenski
A
A
Department of Pathology and the Robert H. Lurie Cancer Center, Northwestern University Medical School, Chicago, Illinois 60611, USA. a-chlenski@nwu.edu
Nakashiro
K
K
Ketels
K V
KV
Korovaitseva
G I
GI
Oyasu
R
R
D000230:Adenocarcinoma; D000728:Androgens / Q000494:pharmacology; D000818:Animals; D019175:DNA Methylation; D004252:DNA Mutational Analysis; D004273:DNA, Neoplasm / Q000378:metabolism; D015972:Gene Expression Regulation, Neoplastic; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D011401:Promoter Regions, Genetic; D011471:Prostatic Neoplasms; D011944:Receptors, Androgen / Q000235:genetics*; D014158:Transcription, Genetic; D014407:Tumor Cells, Cultured
D000728:Androgens; D004273:DNA, Neoplasm; D011944:Receptors, Androgen