Kin-Mang Lau

Rat estrogen receptor-alpha and -beta, and progesterone receptor mRNA expression in various prostatic lobes and microdissected normal and dysplastic epithelial tissues of the Noble rats.

Semiquantitative RT-PCR was used to determine if transcripts of the two estrogen receptor (ER) subtypes, ER alpha and ER beta, and the progesterone receptor (PR) are differentially expressed and/or regulated in the various normal lobes of the Noble (NBL) rat prostate. We found that ER beta mRNA was present at comparable, high levels in all three major prostatic lobes: dorsal (DP), lateral (LP) and ventral (VP) prostate. ER alpha mRNA was, however, expressed at low levels among the various lobes in the following descending order of abundance: LP>DP>VP. Expression of PR transcript was low and paralleled the expression pattern of ER alpha mRNA. Treatments of rats with testosterone (T) plus estradiol-17beta (E2) (T+E2) or T alone induced no discernible alterations in ER alpha, ER beta, and PR mRNA levels in the VP, DP and LP, while those with E2 caused a general decline in the expression of all three transcripts. We then studied the expression of the three receptors in the normal and dysplastic epithelium of the dorsolateral prostates (DLPs) of rats treated with T+E2. Comparable levels of ER beta mRNA were found in microdissected dysplastic and normal epithelia. In contrast, significantly higher levels of PR mRNA were present in epithelial samples from dysplastic acini. ER alpha mRNA was not detected in any of the microdissected epithelial samples. Results from this study suggest that upregulation of PR mRNA expression, likely mediated via ER beta action, is involved in the genesis of T+E2-induced dysplasia in this animal model.

Expression of proinflammatory genes during estrogen-induced inflammation of the rat prostate.

Exposure of male Wistar rats to estradiol‐17β (E2) in the presence or absence of dihydrotestosterone propionate (DHT) was previously shown to result in prostate inflammation. The present study examines, for the first time, changes in the expression level of several proinflammatory genes during the course of this experimentally induced prostatitis.

Altered expression of BRCA1, BRCA2, and a newly identified BRCA2 exon 12 deletion variant in malignant human ovarian, prostate, and breast cancer cell lines

Germline mutations of BRCA1 and BRCA2 predispose to hereditary breast, ovarian, and possibly prostate cancer, yet structural mutations in these genes are infrequent in sporadic cancer cases. To better define the involvement of these genes in sporadic cancers, we characterized expression levels of BRCA1 and BRCA2 transcripts in cancer cell lines derived from neoplasms of the ovary, prostate, and breast and compared them with those expressed in primary cultures of normal epithelial cells established from these organs. We observed upregulation of BRCA1 and/or BRCA2 expression in six of seven ovarian cancer cell lines (OVCA420, OVCA429, OVCA432, ALST, DOV13, and SKOV3) when compared with levels found in normal ovary surface epithelial cells. Furthermore, five cancerous or immortalized prostatic epithelial cell lines (BPH‐1, TSU‐Pr1, LNCaP, PC‐3, and DU145) also expressed higher levels of BRCA1 and/or BRCA2 mRNA than did primary cultures of normal prostatic epithelial cells. In contrast, only the estrogen receptor–positive MCF‐7 cell line overexpressed these messages, whereas the estrogen receptor–negative breast cancer cell lines Hs578T, MDA‐MB‐231, and MDA‐MB‐468 showed no change in expression levels when compared with normal breast epithelial cells. In addition, expanding on our recent identification of a novel BRCA2 transcript variant carrying an in‐frame exon 12 deletion (BRCA2Δ12), we report increased expression of this variant in several ovarian, prostate, and mammary cancer cell lines (OVCA420, OVCA433, ALST, DOV13, SKOV3, TSU‐Pr1, DU145, and MDA‐MB‐468). Most notably, high levels of BRCA2Δ12 mRNA were detected in an estrogen receptor–positive breast cancer cell line, MCF‐7, and in an androgen‐independent prostate cancer cell line, DU‐145. Interestingly, the wild‐type BRCA2 transcript was barely detectable in DU145, which could be used as a model system for future investigations on BRCA2Δ12 function. Taken together, our data suggest disruption of BRCA1 and/or BRCA2 gene expression in certain epithelial cancer cell lines of the ovary, prostate, and breast. Because wild‐type BRCA1 and BRCA2 gene products increase during cell‐cycle progression and are believed to exert growth‐inhibitory action, enhanced expression of these genes in cancer cells may represent a negative feedback mechanism for curbing proliferation in fast‐growing cells. At present, the functionality of BRCA2Δ12 remains elusive. Mol. Carcinog. 28:236–246, 2000.

Expression of RFG/ELE1alpha/ARA70 in normal and malignant prostatic epithelial cell cultures and lines: regulation by methylation and sex steroids.

RET fused gene (RFG)/ELE1α/androgen receptor–associated protein 70(ARA70) was first found to be involved in the activation of the RET proto‐oncogene in thyroid neoplasm and has recently been shown to be a ligand‐dependent transcriptional coregulator for androgen receptor (AR). The functionality of RFG/ELE1α/ARA70 remains controversial, and little is known about factors regulating its expression in the prostate. Of significant interest is whether this molecule is involved in prostate carcinogenesis. Using reverse transcriptase–polymerase chain reaction semiquantitation, we compared RFG/ELE1α/ARA70 mRNA levels in four prostate cancer cell lines (LNCaP, TSU‐Pr1, DU‐145, and PC‐3) with those found in primary cultures of normal prostatic epithelial cells (PrECs). In addition, we examined the effects of androgen and antiandrogen, estrogen and antiestrogen, and a demethylating agent on RFG/ELE1α/ARA70 mRNA expression levels in AR− and AR+ PC‐3 cells. Reduced levels of RFG/ELE1α/ARA70 message were observed in all four prostate cancer cell lines when compared with normal PrECs in primary cultures. RFG/ELE1α/ARA70 mRNA levels in PC‐3 cells, which express both estrogen receptor subtypes, were upregulated by 17β‐estradiol and inhibited by the antiestrogen ICI‐182780. In PC‐3(AR+) cells, which were genetically engineered to express AR, exposure to androgen upregulated RFG/ELE1α/ARA70 mRNA expression, whereas treatment with 4‐hydroxyflutamide lowered expression of this transcript. Furthermore, treatment of DU‐145 cells, which did not express RFG/ELE1α/ARA70 transcripts, with a demethylating agent reactivated transcription of this gene. Polymerase chain reaction analyses of monochromosomal human‐rodent hybrid panels localized a putative RFG/ELE1α/ARA70 isoform on human chromosome 5q31.1‐31.2. In summary, we identified sex hormones and DNA hypermethylation as regulators of RFG/ELE1α/ARA70 expression in prostate cancer cells. In addition, we found reduced levels of RFG/ELE1α/ARA70 expression in prostate cancer cell lines when compared with expression levels in normal PrECs in culture. These findings suggest that RFG/ELE1α/ARA70 may be involved prostate carcinogenesis and that it may serve as a key mediator of estrogen–androgen synergism. Mol. Carcinog. 30:1–13, 2001.