Wilms' tumor protein 1: an early target of progestin regulation in T-47D breast cancer cells that modulates proliferation and differentiation

Abstract

Progesterone regulates the proliferation and differentiation of normal mammary epithelium. In breast cancer cells, progesterone and its synthetic analogs, progestins, induce long-term growth inhibition and differentiation. However, the mechanisms responsible are not fully understood. When T-47D breast cancer cells were treated with the synthetic progestin ORG 2058 (16a-ethoxy-21-hydroxy-19-norpregn-4-en-3,20-dione), all isoforms of Wilms' tumor protein 1 (Wt1) mRNA and protein were rapidly downregulated. We reasoned that the decrease in Wt1 levels may contribute to the long-term antiproliferative and differentiative effects of progestins as proliferation and differentiation are known end points of Wt1 action. Consistent with this idea, Wt1 small interfering RNA led to a decrease in S phase and cyclin D1 levels, and increased Oil-Red-O staining, indicating increased lipogenesis. Conversely, overexpression of Wt1 attenuated the decrease in S phase induced by ORG 2058 at 48-96 h. This was accompanied by the sustained expression of cyclin D1 despite progestin treatment, and increased levels of retinoblastoma (Rb) phosphorylation at sites targeted by cyclin D1-Cdk4 (Ser249/Thr252). Wt1 overexpression also attenuated the ORG 2058-mediated increase in fatty acid synthase levels and reduced lipogenesis. Thus, Wt1 downregulation was sufficient to mimic the effects of progestin and was necessary for complete progestinmediated proliferative arrest and subsequent differentiation. Furthermore, Wt1 overexpression modulated the effects of progestins but not anti-estrogens or androgens. These results indicate that Wt1 is an important early target of progestins that regulates both proliferation and differentiation in breast cancer cells.

Detection of Expressional Changes Induced by Intrauterine Growth Restriction in the Developing Rat Mammary Gland via Exploratory Pathways Analysis

“…So far the exact role of WT1 in the female reproductive system is not fully understood. In healthy endometrium progesterone induces WT1 isoforms which in turn leads to the differentiation into decidua [64], while in breast cancer cells progesterone analogs reduce WT1 expression thereby inducing differentiation [65]. As we examined mammary tissue without overt pathologic alterations, the observed induction of WT1 might point to premature differentiation, which is supported by the findings of our whole mount analyses showing smaller mammary glands and by the fact that an early increase in progesterone is detected in IUGR animals at day 28.…”

High Wilms’ tumor 1 mRNA expression correlates with basal-like and ERBB2 molecular subtypes and poor prognosis of breast cancer

“…Though Miyoshi et al (18) found that the prognosis of patients with high WT1 expression was significantly worse than that in patients with low WT1 expression, Camcı et al failed to confirm this finding in a later study (23). In the present study, we concluded that WT1 mRNA high expression predicted poor prognosis of breast cancer patients when using 3.1 as cutoff value, which might be due to the facts that WT1 could promote proliferation, invasion, migration, response to hypoxia and drug resistance of cancer cells (19)(20)(21)(22)35,37,38).…”

“…Miyoshi et al found that WT1 mRNA significantly correlated with the poor prognosis of breast cancer (18). In addition, WT1 could promote the proliferation and restrain the apoptosis of breast cancer cells (19)(20)(21), all of which indicate that WT1 might serve as an oncogene in breast cancer. Therefore, it is necessary to clarify the oncogenic or tumor suppressive role of WT1 in breast cancer.…”

Flubendazole, FDA-approved anthelmintic, targets breast cancer stem-like cells

“…To explore whether flubendazole induces breast cancer cell differentiation, we performed Oil Red O staining in CS-like cell enriched MDA-MB-231 cells before and after flubendazole treatment (0.125 μM, 3 weeks) [31]. We observed that flubendazole dramatically increased positively staining cells ( p <0.05) (Fig.…”

“…Oil-Red-O staining for the detection of lipid droplets was performed as previously described [31]. Images were obtained under microscope.…”