Results

The results of RT-PCR showed that all immortalized prostatic epithelial cell lines and cancer cell lines, and two CWR22 xenografts expressed one to three isoforms ofERRs (a, ß, y) (Figure 1). Among the three ERR isoforms, ERRa transcripts were expressed in all cell lines and CWR22 xenografts, with weaker expression in DU 145 and PC-3. ERRß transcripts were weakly detected in the four immortalized cell lines (HPr-1, HPr-1 AR, PNT1A, PNT2), three cancer cell lines (LNCaP, PC-3, MDA PCa 2b) and CWR22R xenograft. ERRy transcripts were expressed variably in different cell lines and CWR22 xenografts, with higher levels in C4-2B, PC-3, CWR22, and CWR22R xenografts.

Figure 1. RT-PCR of ERRs and ERs in different prostatic cell lines and CWR22 xenografts. Controls for RT-PCR were in the absence of reverse transcriptase (no RT), total RNA (no RNA) and cDNA templates (no cDNA).

ERRs also exhibited similar patterns in human hyperplastic and neoplastic prostatic tissues as shown in cell lines and xenografts. ERRa transcripts were detected in all hyperplastic and neoplastic samples, whereas and were variably expressed in hyperplastic tissues but weakly expressed or absent in neoplastic tissues. The gene expression of other steroid hormone receptors in these cell lines and xenografts was also examined and compared to ERRs. In summary, most cell lines and the two CWR22 xenografts positively expressed ERa (except DU 145, MDA PCa 2b, CWR22Rvl), ERp (Figure 1), androgen receptor (except PNT2, CA-HPV-10, DU 145), progesterone receptor (except HPr-1, HPr-1AR, PNT2, CA-HPV-10, PC-3), and glucocorticoid receptor. The results of gene expression of ERRs and different steroid hormone receptors as detected by RT-PCR are summarized in Table 1.

Figure 2. Immunohistochemistry of ERRy in normal human prostate. 2a and 2b: The glandular epithelia show positive immunosignals (2a, X100; 2b, X200). 2c: Control section stained with blocking solution with 3 % BSA (X200).

Table 1: Summary of Gene Expression of ERRs and Steroid Hormone Receptors in Prostatic Cell Lines and Xenografts'.

Cell lines and tumor xenografts

RRRa

ERRß

ERRy

ERa

ERß

AR

PR

GR

HPr-1

+

+

+

++

++

+

-

+-H-

HPr-1 AR

+

+

+

+

++

+++

-

+++

PNT1A

++

+

+

+

++

+

H—h

+++

PNT2

++

+

+

++

+

-

-

+++

CA-HPV-10

++

-

++

1 !

++

-

-

+++

LNCaP

+

+

++

+

+

++

++

++

C4-2B

i

-

+++

+

+

++

+++

+++

DU 145

+

-

-

-

+

-

I* ■}

PC-3

+

++

++

+

+

-

+++

MDA PCa 2b

++

++

-

-

+++

+++

+

+++

CWR22

+

-

+++

+

++

+++

-H-

+-H-

CWR22R

+

+

+++

+

++

+++

+

+++

CWR22Rv 1

++

-

-

-

+

++

+

++

1 Expression levels are graded in arbitrary scales: (-) Negative. (+) Weakly expressed. (++) Moderately expressed. (+++) Highly expressed.

Figure 3. Western blot analysis of ERRy in prostatic cell lines and tumor xenografts. The antiserum recognizes a band of 51 kDa in LNCaP and two CWR22 xenografts but not in DU 145 and PC-3.

Figure 3. Western blot analysis of ERRy in prostatic cell lines and tumor xenografts. The antiserum recognizes a band of 51 kDa in LNCaP and two CWR22 xenografts but not in DU 145 and PC-3.

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