Opposing Effects of Runx2 and Estradiol on Breast Cancer Cell Proliferation: In Vitro Identification of Reciprocally Regulated Gene Signature Related to Clinical Letrozole Responsiveness

Abstract

Purpose To assess the clinical significance of the interaction between estrogen and Runx2 signaling, previously demonstrated in vitro. Experimental design MCF7/Rx2dox BCa cells were treated with estradiol and/or doxycycline to induce Runx2, and global gene expression was profiled to define genes regulated by estradiol, Runx2, or both. Anchorage-independent growth was assessed by soft agar colony formation assays. Expression of gene-sets defined using the MCF7/Rx2dox system was analyzed in pre- and on-treatment biopsies from hormone receptor-positive patients undergoing neo-adjuvant letrozole treatment in two independent studies, and short-term changes in gene expression were correlated with tumor size reduction or Ki67 index at surgery. Results Reflecting its oncogenic property, estradiol strongly promoted soft agar colony formation, whereas Runx2 blocked this process suggesting tumor suppressor property. Transcriptome analysis of MCF7/Rx2dox cells treated with estradiol and/or doxycycline demonstrated reciprocal attenuation of Runx2 and estrogen signaling. Correspondingly in BCa tumors, expression of estradiol- and Runx2-regulated genes was inversely correlated; and, letrozole increased expression of Runx2-stimulated genes as defined in the MCF7/Rx2dox model. Of particular interest was a gene-set upregulated by estradiol and downregulated by Runx2 in vitro; its short-term response to letrozole treatment associated with tumor size reduction and Ki67 index at surgery better than other estradiol-regulated gene-sets. Conclusion This work provides clinical evidence for the importance of antagonism between Runx2 and E2 signaling in BCa. Likely sensing the tension between them, letrozole responsiveness of a genomic node, positively regulated by estradiol and negatively regulated by Runx2 in vitro, best correlated with the clinical efficacy of letrozole treatment.

Detection of RUNX2 gene expression in cumulus cells in women undergoing controlled ovarian stimulation

“…RUNX2 suppresses estrogen activity by decreasing the effect of estradiol on reporter gene expression driven by the estrogen receptor response element [10]. Recent studies on breast cancer cells disclosed that ER-α physically binds RUNX2 and inhibits expression of several RUNX2 target genes, providing a strong antagonistic correlation between the two genes in a different cellular type [22,23]. This opposing effect is verified by our results.…”

Differential Effects of RUNX2 on the Androgen Receptor in Prostate Cancer: Synergistic Stimulation of a Gene Set Exemplified by SNAI2 and Subsequent Invasiveness

“…Consistent with the involvement of the respective DNA-binding domains in their physical interaction (8, 29), attenuation of the androgen response after RUNX2 induction was associated with decreased recruitment of AR to Type I genes (this study); and, attenuation of the RUNX2 response by androgens was associated with compromised recruitment to its targets (8). In breast cancer cells, a similar relationship of reciprocal attenuation has been documented for most RUNX2- and most estrogen-responsive genes (25, 26). Interestingly, however, RUNX2-stimulated SNAI2 expression in breast cancer cells followed the global trend and was attenuated by estradiol, potentially contributing to the anti-RUNX2 and protective effects that estradiol had with regard to breast cancer cell invasiveness (20).…”

Association of CYP39A1, RUNX2 and Oxidized Alpha-1 Antitrypsin Expression in Relation to Cholangiocarcinoma Progression

“…It has been known that RUNX2 controls genes involved in sterol/steroid metabolism, including Cyp11a1, Cyp39a1, Cyp51, Lss, and Dhcr7, discovered in murine osteoprogenitor cells (Teplyuk et al, 2009). In addition, the tumor suppression property of RUNX2 has been reported in breast cancer cell lines in blocking the effect of estradiol, resulting in inhibiting tumor growth (Chimge et al, 2012). Notably, we found that high expression of RUNX2 in CCA was significantly related with male than female gender.…”