Inflammatory breast cancer (IBC) is the most lethal and least understood form of advanced breast cancer. Its lethality originates from its nature of invading the lymphatic system and absence of a palpable tumor mass. Different from other metastatic breast cancer cells, IBC cells invade by forming tumor spheroids that retain E-cadherin-based cell–cell adhesions. Herein we describe the potential of the medicinal mushroom Ganoderma lucidum (Reishi) as an attractive candidate for anti-IBC therapy. Reishi contains biological compounds that are cytotoxic against cancer cells. We report the effects of Reishi on viability, apoptosis, invasion, and its mechanism of action in IBC cells (SUM-149). Results show that Reishi selectively inhibits cancer cell viability although it does not affect the viability of noncancerous mammary epithelial cells. Apoptosis induction is consistent with decreased cell viability. Reishi inhibits cell invasion and disrupts the cell spheroids that are characteristic of the IBC invasive pathology. Reishi decreases the expression of genes involved in cancer cell survival and proliferation (BCL-2, TERT, PDGFB), and invasion and metastasis (MMP-9), whereas it increases the expression of IL8. Reishi reduces BCL-2, BCL-XL, E-cadherin, eIF4G, p120-catenin, and c-Myc protein expression and gelatinase activity. These findings suggest that Reishi is an effective anti-IBC therapeutic.

To investigate the effects soy isoflavones in established cancers, the role of genistein, daidzein, and combined soy isoflavones was studied on progression of subcutaneous tumors in nude mice created from green fluorescent protein (GFP) tagged-MDA-MB-435 cells. Following tumor establishment, mice were gavaged with vehicle or genistein or daidzein at 10 mg/kg body weight (BW) or a combination of genistein (10 mg/kg BW), daidzein (9 mg/kg BW), and glycitein (1 mg/kg BW) three times per week. Tumor progression was quantified by whole body fluorescence image analysis followed by microscopic image analysis of excised organs for metastases. Results show that daidzein increased while genistein decreased mammary tumor growth by 38 and 33% respectively, compared to vehicle. Daidzein increased lung and heart metastases while genistein decreased bone and liver metastases. Combined soy isoflavones did not affect primary tumor growth but increased metastasis to all organs tested, which include lung, liver, heart, kidney, and bones. Phosphoinositide-3-kinase (PI3-K) pathway real time PCR array analysis and western blotting of excised tumors demonstrate that genistein significantly downregulated 10/84 genes, including the Rho GTPases RHOA, RAC1, and CDC42 and their effector PAK1. Daidzein significantly upregulated 9/84 genes that regulate proliferation and protein synthesis including EIF4G1, eIF4E, and survivin protein levels. Combined soy treatment significantly increased gene and protein levels of EIF4E and decreased TIRAP gene expression. Differential regulation of Rho GTPases, initiation factors, and survivin may account for the disparate responses of breast cancers to genistein and daidzein diets. This study indicates that consumption of soy foods may increase metastasis.Electronic supplementary materialThe online version of this article (doi:10.1007/s10585-010-9336-x) contains supplementary material, which is available to authorized users.

Background: The molecular mechanisms of soy isoflavones in metastatic cancer remain to be elucidated. Results: Equol, a daidzein metabolite, regulates eIF4G-mediated cap-independent protein synthesis initiation of proteins relevant for cancer malignancy. Conclusion: Equol is a potent regulator of the cancer promoting effects of dietary daidzein. Significance: Consumption of soy may not be advisable for patients with aggressive breast cancer.

The role of soy foods in cancer prevention is known but their effects on cancer metastasis remain to be understood. The purpose of this study is to investigate the effects and mechanism of action of dietary soy isoflavones in established carcinomas. This objective was achieved by testing the effect of the individual and combined soy isoflavones on progression of mammary fat pad tumors in nude mice created from green fluorescent protein (GFP) tagged-MDA-MB-435 metastatic cancer cells. Following tumor establishment, mice were orally gavaged with vehicle or soy isoflavones: genistein (10 mg/kg body weight (BW)), daidzein (10 mg/kg BW), or genistein (50%), daidzein (40%), and glycitein (10%) three times per week. Tumor progression was quantified by whole body fluorescence image analysis twice a week followed by microscopic image analysis of excised organs for metastases. Results show that daidzein significantly increased while genistein decreased mammary tumor growth by 38% and 33% respectively. Daidzein increased lung, heart, and kidney metastases while genistein decreased bone and liver metastases. Combined soy isoflavones did not affect primary mammary tumor growth but increased metastasis to all organs tested; i.e. lung, liver, heart, kidney, and bones. Phosphoinositide-3-kinase (PI3-K) pathway real time PCR array analysis on excised tumors demonstrates that genistein significantly downregulated 26% of the genes tested, including Rho GTPases RHOA, RAC1, and CDC42, and their downstream effector PAK1 that are known regulators of cancer cell invasion, and thus, metastasis. Daidzein upregulated 14% of the genes including CCND1, GRB2, MAPK1, JUN, CTNNB1, IRS1, EIF4G1, and GSK3B that regulate proliferation and protein synthesis. Combined soy treatment significantly increased EIF4E and decreased TIRAP expression. Western blotting of mammary tumor extracts following genistein, daidzein, or combined soy isoflavones show that genistein downregulates RhoA, Rac1, and Cdc42 while daidzein upregulates Rac1, GSK3, and eIF4G1 protein expression. Combined soy isoflavones did not show significant differences in expression of Rho GTPases or PAK. In conclusion, downregulation of Rho GTPases by genistein may reduce mammary tumor growth and metastasis while upregulation of eIF4G and Rac1 by daidzein may increase mammary tumor growth and metastasis. Consumption of soy foods that contain both genistein and daidzein may neutralize their differential effects on primary tumor growth. The increased metastasis but not primary tumor growth in response to combined soy isoflavones indicates that even though dietary soy has been implicated in cancer prevention, caution must be exercised in dietary decisions of soy foods for cancer patients and survivors. This research was supported by AICR IIG 03-31-06 and NIH/NIGMS SC3GM084824 to SD and NCCR/NIH 2G12RR003035 and S06GM050695 to UCC. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 5725.

The role of dietary soy in cancer has been the subject of intense investigation and is thought to be cancer preventive. However, the beneficial effects of soy on established breast cancer is controversial. We recently demonstrated that dietary daidzein and combined soy isoflavones (genistein, daidzein, and glycitein) promoted breast cancer progression in a nude mouse model by increasing both primary mammary tumor growth and metastasis. Dietary daidzein significantly upregulated cancer promoting molecules including eukaryotic protein synthesis initiation factors (eIF) eIF4G and eIF4E. Herein, using tumors from mice treated orally with daidzein, we show that increased eIF expression is associated with expression of mRNAs with long structured 5′ untranslated regions and internal ribosomal entry sites (IRES) that are sensitive to eIF4E and eIF4G levels. We then tested the hypothesis that daidzein upregulates protein synthesis initiation in breast cancer, but found that daidzein treatment did not affect the levels of eIFs in the same MDA-MB-435 cell line in vitro. Therefore, we tested the effect of equol that is metabolized from daidzein by the gut bacteria in mice and humans. Results show that equol specifically upregulated eIF4G, but not eIF4E, in MDA-MB-435 and MDA-MB-231 human breast cancer cells. Equol treatment also increased gene and protein expression of c-MYC and protein expression of other cell survival and proliferation promoting molecules with IRES sites. The elevated eIF4G in response to equol was not associated with eIF4E in a cap binding co-capture assay. Therefore, upregulation of eIF4G by equol may regulate cap-independent protein synthesis initiation resulting in cancer cell survival, proliferation, and thus, tumor progression. This research was supported by grant numbers US Army/BCRP W81XWH-11-1-0199 to CD, to NIH/NIGMS SC3GM084824 to SD Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 1988. doi:1538-7445.AM2012-1988