Progesterone and estradiol effects on SRC-1 and SRC-3 expression in human astrocytoma cell lines

Abstract

Progesterone (P(4)) and estradiol (E(2)) regulate many cell functions through their interaction with specific intracellular receptors, which require the participation of coactivators such as SRC-1 and SRC-3 for enhancing their transcriptional activity. Coactivator expression is altered in many cancers and in some of them their expression is regulated by P(4) and E(2). In this study, we determined progesterone and estrogen receptor isoform expression in two human astrocytoma cell lines with different evolution grade (U373, grade III; and D54, grade IV) by Western Blot. We studied the role of P(4) and E(2) on SRC-1 and SRC-3 expression in U373 and D54 cell lines by RT-PCR and Western blot. In U373 cells, P(4) did not modify SRC-1 expression, but in D54 cells it increased SRC-1 mRNA expression after 12 h of treatment without significant changes after 24 h. P(4) also increased SRC-1 protein content after 24 h, but reduced it after 48 h. E(2) did not change SRC-1 expression in any cell line. SRC-3 expression was not regulated by either E(2) or P(4). Our data suggest that SRC-1 and SRC-3 expression is differentially regulated by sex steroid hormones in astrocytomas and that P(4) regulates SRC-1 expression depending on the evolution grade of human astrocytoma cells.

Progesterone receptor and SRC-1 participate in the regulation of VEGF, EGFR and Cyclin D1 expression in human astrocytoma cell lines

“…Interestingly, we observed that P increases SRC-1 protein content in D54 cells transfected with shSRC-1 and shControl. Consistent with these observations in our laboratory we have demonstrated that P increases SRC-1 mRNA expression in D54 cells 12 h after its administration, this increase was reflected at SRC-1 protein content 12 h later [17]. This could limit the effects of SRC-1 depletion by shSRC-1 transfection.…”

“…In fact, it has been reported that PR-A and PR-B modify the expression of different genes in the uterus and breast cancer cells [52]. We have recently reported that P significantly increases SRC-1 expression in D54 cells but not in U373 cells [17]. This suggests a cell-specific modulation of SRC-1 expression by P in astrocytomas that should be related to an increase in transcriptional activation of PR in D54 cells.…”

“…In astrocytomas, a direct relation between the content of PR and the tumor grade has been reported, suggesting that PR-positive tumors possess a high proliferative potential [8,14]. Our group has found that P induces cell proliferation in U373 and D54 human astrocytoma cell lines (grades III and IV, respectively), which is blocked by its antagonist RU 486, suggesting that P effects are mediated by PR [15] whose both isoforms have been detected in U373 and D54 cells [16,17].It has been demonstrated that the expression of VEGF, EGFR and cyclin D1 directly correlates with the tumor grade and the recurrence of astrocytomas [3,5]. Several studies have established that natural and synthetic progestins increase VEGF, EGFR and cyclin D1 expression (mRNA and protein) in human endothelial, Ishikawa endometrial carcinoma and breast cancer cells (BT-474, T47D and HCC-1428) through a PR-mediated mechanism [18][19][20][21].…”

“…Previous studies in our laboratory have demonstrated that PR isoforms expression pattern was different in U373 and D54 cells. Thus, PR-B was the predominant isoform in U373 cells, whereas in D54 cells PR-A was the predominant one [16,17]. This suggests that PR isoforms should exert a differential role in the regulation of VEGF, EGFR and cyclin D1 by P in human astrocytoma cells.…”

“…It has been reported that disruption of SRC-1 gene in mice suppresses breast cancer metastasis [34]. Studies in our laboratory have demonstrated that SRC-1 is expressed in U373 and D54 cells, and its expression was up-regulated by P in D54 cells [17].…”