Rhodiola crenulata induces an early estrogenic response and reduces proliferation and tumorsphere formation over time in MCF7 breast cancer cells.

BACKGROUND: Rhodiola crenulata is a Tibetan mountainous plant, commonly used in Eastern alternative medicine. Many phytochemicals possess estrogenic activity, a critical regulator of proliferation in mammary epithelial cells. We have previously characterized anti-cancer properties of R. crenulata in aggressive triple negative breast cancer cells, lacking the expression of estrogen receptor. Currently, it is unknown whether R. crenulata exerts estrogenic effects and as such consumption may be a concern for women with estrogen receptor positive breast cancer that use Rhodiola sp. to relieve mild to moderate depression. PURPOSE: In this study, we wished to determine whether a hydroalcoholic fraction of the R. crenulata root extract exhibits estrogenic activity in estrogen receptor positive (ER+) breast cancer cells in vitro and whether it affects normal mammary epithelial ER target gene expression in vivo. METHODS: ER transcriptional activity was analyzed in MCF7 cells expressing an ERE reporter construct and confirmed via qPCR of endogenous ER target genes. We also monitored cellular proliferation over time. Additionally, to assess stem-like properties in MCF7 cells, we performed a tumorsphere formation assay under anchorage independent conditions. We examined whether R. crenulata treatment reduced ß-catenin levels via Western blotting and measured ß-catenin transcriptional activity by a reporter assay. To examine the effects of R. crenulata on normal mammary epithelial cells, we performed immunohistochemical staining of ER and PR in the mammary glands of mice fed R. crenulata for 12 weeks. RESULTS: We show an initial activation of ER transcriptional activity by dual reporter assay, qPCR and proliferation of MCF7 ER+ cells in response to 24 h of R. crenulata treatment. However, upon longer treatment basal and R. crenulata induced transcriptional activity was suppressed. There was a decrease in cell doubling times and a decrease in tumorsphere formation. In association with these changes, ERα transcript levels were decreased and active ß-catenin levels were reduced in the cells treated for 2 weeks. Finally, we show no change in estrogen targets in normal mammary cells in vivo. CONCLUSION: These data suggest that the R. crenulata extract contains components with estrogenic activity. However, R. crenulata treatment could still be protective in ER+ breast cancer cells, as longer treatment reduced the transcriptional activity of ß-catenin and ER responses leading to reduced proliferation and tumorsphere formation. Furthermore, administration of 20 mg/kg/day R. crenulata to mice did not have an observable effect on mammary epithelial ERα target gene expression in vivo.

Antineoplastic effects of Rhodiola crenulata treatment on B16-F10 melanoma.

Melanoma is an aggressive form of skin cancer with limited treatment options for advanced stage disease. Early detection and wide surgical excision remain the initial mode of treatment for primary tumors thus preventing metastases and leading to improved prognosis. Through this work, we have evaluated the antineoplastic effects of Rhodiola crenulata (R. crenulata) root extracts on the B16-F10 melanoma cell line, both in vitro and in vivo. We observed that R. crenulata treatment resulted in increased cell death as well as a reduction in tumor cell proliferation and migration in vitro. Additionally, we observed that R. crenulata decreased the expression of integrin ß1 and vimentin and increased the expression of E-cadherin. Further, in mice treated with a topical R. crenulata-based cream therapy, tumors were more likely to have a radial growth pattern, a reduction in mitotic activity, and an increase in tumor necrosis. We also observed that mice drinking water supplemented with R. crenulata displayed a reduction of metastatic foci in disseminated models of melanoma. Collectively, these findings suggest that R. crenulata exhibits striking antitumorigenic and antimetastatic properties and that this extract may harbor potential novel adjuvant therapy for the treatment of melanoma.

Rhodiola crenulata inhibits Wnt/ß-catenin signaling in glioblastoma.

BACKGROUND: Rhodiola crenulata is a perennial plant that grows in the high altitudes of Eastern Europe and Asia. R crenulata has been used for many years in Eastern traditional medicine for a variety of medicinal purposes and it has been shown to elicit antineoplastic effects. The purpose of this study is to determine if R crenulata extract exhibits antitumor properties on glioblastoma multiforme (GBM), the most common and aggressive primary brain tumor. MATERIALS AND METHODS: Human U87 GBM cells were treated with 200 µg/mL of R crenulata or vehicle control. Cell proliferation was measured via MTS assay and clonogenic assay. The expressions of glial fibrillary acidic protein, a protein marker of differentiation, E-cadherin, and non-phospho active ß-catenin were measured with immunocytochemistry. Neurosphere assay was performed in low attachment plates. Activity of the Wnt/ß-catenin transcriptional activation was assessed via a dual-luciferase assay. RESULTS: MTS and clonogenicity assays revealed a decrease in proliferation with R crenulata therapy with an increased sensitivity to radiation. Immunocytochemistry revealed that R crenulata induced glial fibrillary acidic protein and E-cadherin expression suggestive of a more differentiated state. In agreement with the change in differentiation neurosphere formation was decreased upon treatment with R crenulata. ß-Catenin dual reporter assay revealed a decrease in Wnt promoter activity after treatment with R crenulata; this was supported by a decrease in nuclear localization of ß-catenin. CONCLUSIONS: Treatment with R crenulata extract effectively suppresses proliferation, stimulates differentiation, and eliminates tumorsphere formation of GBM cells in vitro. The observed effects are associated with inhibition of Wnt/ß-catenin signaling pathway.

The effects of diet induced obesity on breast cancer associated pathways in mice deficient in SFRP1.

BACKGROUND: Secreted frizzled-related proteins (SFRPs) are a family of proteins that block the Wnt signaling pathway and loss of Sfrp1 expression is observed in breast cancer. The molecular mechanisms by which obesity contributes to breast tumorigenesis are not well defined, but involve increased inflammation. Mice deficient in Sfrp1 show enhanced mammary gland inflammation in response to diet induced obesity (DIO). Furthermore, mammary glands from Sfrp1-/- mice exhibit increased Wnt signaling, decreased cell death responses, and excessive hyper branching. The work described here was initiated to investigate whether obesity exacerbates the aforementioned pathways, as they each play a key roles in the development of breast cancer. FINDINGS: Wnt signaling is significantly affected by DIO and Sfrp1-/- loss as revealed by analysis of Myc mRNA expression and active ß-catenin protein expression. Furthermore, Sfrp1-/- mice fed a high fat diet (HFD) exhibit an increase in mammary cell proliferation. The death response is also impaired in the mammary gland of Sfrp1-/- mice fed a normal diet (ND) as well as a HFD. In response to γ-irradiation, mammary glands from Sfrp1-/- mice express significantly less Bax and Bbc3 mRNA, caspase-3 positive cells, and p53 protein. The expression of Wnt4 and Tnfs11 are critical for normal progesterone mediated mammary gland development and in response to obesity, Sfrp1-/- mice express significantly more Wnt4 and Tnfs11 mRNA expression. Evaluation of progesterone receptor (PR) expression showed that DIO increases the number of PR positive cells. CONCLUSIONS: Our data indicate that the expression of Sfrp1 is a critical factor required for maintaining appropriate cellular homeostasis in response to the onset of obesity.

Mice deficient in Sfrp1 exhibit increased adiposity, dysregulated glucose metabolism, and enhanced macrophage infiltration.

The molecular mechanisms involved in the development of obesity and related complications remain unclear. Wnt signaling plays an important role in preadipocyte differentiation and adipogenesis. The expression of a Wnt antagonist, secreted frizzled related protein 1 (SFRP1), is increased in response to initial weight gain, then levels are reduced under conditions of extreme obesity in both humans and animals. Here we report that loss of Sfrp1 exacerbates weight gain, glucose homeostasis and inflammation in mice in response to diet induced obesity (DIO). Sfrp1(-/-) mice fed a high fat diet (HFD) exhibited an increase in body mass accompanied by increases in body fat percentage, visceral white adipose tissue (WAT) mass, and adipocyte size. Moreover, Sfrp1 deficiency increases the mRNA levels of key de novo lipid synthesis genes (Fasn, Acaca, Acly, Elovl, Scd1) and the transcription factors that regulate their expression (Lxr-α, Srebp1, Chreb, and Nr1h3) in WAT. Fasting glucose levels are elevated, glucose clearance is impaired, hepatic gluconeogenesis regulators are aberrantly upregulated (G6pc and Pck1), and glucose transporters are repressed (Slc2a2 and Slc2a4) in Sfrp1(-/-) mice fed a HFD. Additionally, we observed increased steatosis in the livers of Sfrp1(-/-) mice. When there is an expansion of adipose tissue there is a sustained inflammatory response accompanied by adipokine dysregulation, which leads to chronic subclinical inflammation. Thus, we assessed the inflammatory state of different tissues and revealed that Sfrp1(-/-) mice fed a HFD exhibited increased macrophage infiltration and expression of pro-inflammatory markers including IL-6, Nmnat, Tgf-ß2, and SerpinE1. Our findings demonstrate that the expression of Sfrp1 is a critical factor required for maintaining appropriate cellular signaling in response to the onset of obesity.