Inhibition of cyclin D expression in human breast carcinoma cells by retinoids in vitro

Abstract

Transfection and transgenic mouse experiments supported an oncogenic role for cyclin D1 in breast cancer. We recently reported that noninvasive carcinoma in situ lesions of the human breast overexpress cyclin D, suggesting that this molecular event may represent a valuable target for chemoprevention. The purpose of the present series of investigations was to identify agents which could reduce the cyclin D expression of breast cells. We report that 9-cis retinoic acid (9-cis RA) and all trans retinoic acid (tRA) inhibited the cyclin D1 and D3 expression levels of human MCF-7, ZR-75 and T-47D breast carcinoma cells in vitro. Where detectable, similar trends were observed in the immortalized, HBL-100 and MCF-10A breast cell lines. Cyclin D2 was undetectable. The e ect of retinoids was both dose-and time-dependent, and correlated with altered cell cycle kinetics and proliferative status. Retinoids were also found to inhibit the expression levels of other cell cycle related proteins, including Cdk2 and Cdk4, resulting in lower kinase activities. In contrast to other breast prevention studies, no synergistic e ect was observed with retinoids and tamoxifen. The data indicate that retinoids can potently reduce cyclin D expression levels in a variety of breast cell lines in vitro, and suggest further consideration of this mechanism for the chemoprevention of breast cancer.

Novel retinoic acid metabolism blocking agents have potent inhibitory activities on human breast cancer cells and tumour growth

“…Furthermore, we also observed significant accumulation of cells in the sub-G1 phase of the treated cells, which may represent cells undergoing apoptosis (Table 3). Given the well-established involvement of cyclins in the regulation of cell cycle progression and the previous findings that cyclin D1 is overexpressed in many cancers and cancer cell lines (Teixeira and Pratt, 1997;Zhou et al, 1997;Niu et al, 2001), we investigated the effects of our RAMBAs on the level of cyclin D1 expression. As shown in Figure 5A, ATRA, RAMBAs and 4-HPR, each significantly decreased cyclin D1 protein expression by 480% in MCF-7 cells as compared with untreated control.…”

RAR agonists stimulate SOX9 gene expression in breast cancer cell lines: evidence for a role in retinoid-mediated growth inhibition

“…The anti-proliferative effect of the RAR-agonist, all-trans retinoic acid (RA), in breast cancer cell lines results from inhibition of growth (Seewaldt et al, 1997a,b;Toma et al, 1997;van der Leede et al, 1995) and this effect appears to result from a delay in the transition between the G0-G1 and S phase of the cell cycle (Seewaldt et al, 1997b(Seewaldt et al, , 1999. Rb, cyclin D and E, cyclin dependent kinases 2, 4, and 6, and their inhibitors p15, p16, p21 and p27 have all been suggested as potential targets for retinoids in normal and malignant breast cells as well as other cell types that are sensitive to retinoidmediated growth inhibition (Langenfeld et al, 1996;Seewaldt et al, 1997b;Zhou et al, 1997). In addition to mediating cell cycle changes, apoptosis of retinoid responsive cells has been observed by several investigators (Jinno et al, 1999;Mangiarotti et al, 1998;Shao et al, 1995;Sheikh et al, 1995;Teixeira and Pratt, 1997).…”

Lycopene inhibition of cell cycle progression in breast and endometrial cancer cells is associated with reduction in cyclin D levels and retention of p27Kip1 in the cyclin E–cdk2 complexes

“…Most interestingly, many anticancer agents, including those used for breast cancer therapy, convey their inhibitory e ect in G 1 phase primarily by reducing cyclin D1 levels. These include pure antiestrogens (Watts et al, 1994), tamoxifen (Planas Silva and Weinberg, 1997), retinoids (Teixeira and Pratt, 1997;Zhou et al, 1997), progestins (Musgrove et al, 1998), as well as 1.25-dihydroxyvitamin D 3 (Wang et al, 1996) and TGF-b (Mazars et al, 1995).…”

“…For example, antiestrogens upregulate the CDK inhibitors p21 Cip1/Waf1 and p27 Kip1 (Watts et al, 1995), whereas retinoic acid does not alter p27 levels but reduces p21 protein abundance (Zhou et al, 1997). The inhibitory e ect of retinoids is mediated partly by reduction in cdk2 protein levels (Teixeira and Pratt, 1997), while antiestrogens and tamoxifen do not alter kinase protein abundance (Planas Silva and Weinberg, 1997;Watts et al, 1995).…”