The answer to chemoprevention has perhaps been available to the general public since the dawn of time. The epigenetic diet is of extreme interest, for research suggests that cruciferous vegetables are not only an important source of nutrients, but perhaps a key to eliminating cancer as life threatening disease. Cruciferous vegetables such as kale, cabbage, Brussels sprouts, and broccoli sprouts contain chemical components, such as sulforaphane (SFN) and indole-3-carbinol (I3C), which have been revealed to be regulators of microRNAs (miRNAs) and inhibitors of histone deacetylases (HDACs) and DNA methyltransferases (DNMTs). The mis-regulation and overexpression of these genes are responsible for the uncontrolled cellular proliferation and viability of various types of cancer cells. The field of epigenetics and its incorporation into modern medicinal investigation is an exponentially growing field of interest and it is becoming increasingly apparent that the incorporation of an epigenetic diet may in fact be the key to chemoprevention.

Since dietary polyphenols can have beneficial effects in prevention and treatment of cancer, we tested the hypothesis that breast cancer patients’ intestinal microbiota is modulated by genistein (GE), an isoflavone found in soy, and that microbial alterations may offset the side effects brought about by chemotherapy. We demonstrated successful humanization of germ-free mice by transplanting fecal samples from breast cancer patients before and after chemotherapy. Mice were then grouped based on chemotherapy status and GE or control diet. We did not find any significant differences between pre-chemotherapy and post-chemotherapy bacterial composition and abundances. Germ-free mice on a GE diet showed differences in microbial composition as compared to mice on control diet. Four weeks after introduction of the customized GE diet, there was distinct clustering of GE-fed mice as compared to the control-fed group. In the gut microbiome of GE-treated humanized mice, there was an increase in abundance of genera Lactococcus and Eubacterium. Phylum Verrucomicrobia showed statistically significant (p = 0.02) differences in abundances between the GE-fed and control-fed groups. There was an increase in bacteria belonging to family Lachnospiraceae and Ruminococcaceae in GE-fed mice. Marked changes were observed in GE catabolism in mice humanized with fecal material from two of three patients’ post-chemotherapy with complete disappearance of 4-ethylphenol and 2-(4-hydroxyphenol) propionic acid conjugates. The post-tumor samples did not show any distinct clustering of the gut microbiota between the two diet groups. There was an increase in latency of about 25% for tumor growth of the humanized mice that were on a GE diet as compared to humanized mice on a control diet. The average tumor size for the GE group was significantly decreased compared to the non-GE group. Collectively, our results suggest that the intestinal microbiota becomes altered with a GE diet before induction of tumor. Our findings indicate that GE modulates the microbiome in humanized mice that may contribute to its effects on increasing the latency of breast tumor and reducing tumor growth.

Little is known about the effects of combinatorial dietary compounds on the regulation of epigenetic mechanisms involved in breast cancer prevention. The human diet consists of a multitude of components, and there is a need to elucidate how certain compounds interact in collaboration. Withaferin A (WA), found in the Indian winter cherry and documented as a DNA methyltransferase (DNMT) inhibitor, and sulforaphane (SFN), a well-known histone deacetylase (HDAC) inhibitor found in cruciferous vegetables, are two epigenetic modifying compounds that have only recently been studied in conjunction. The use of DNMT and HDAC inhibitors to reverse the malignant expression of certain genes in breast cancer has shown considerable promise. Previously, we found that SFN + WA synergistically promote breast cancer cell death. Herein, we determined that these compounds inhibit cell cycle progression from S to G2 phase in MDA-MB-231 and MCF-7 breast cancer. Furthermore, we demonstrate that this unique combination of epigenetic modifying compounds down-regulates the levels of Cyclin D1 and CDK4, and pRB; conversely, the levels of E2F mRNA and tumor suppressor p21 are increased independently of p53. We find these events coincide with an increase in unrestricted histone methylation. We propose SFN + WA-induced breast cancer cell death is attributed, in part, to epigenetic modifications that result in the modulated expression of key genes responsible for the regulation of cancer cell senescence.

We observed geographic and racial/ethnic disparities in breast cancer mortality: NH-Black and Hispanic breast cancer deaths were more concentrated in southern, lower SES counties.

With cancer often classified as a disease that has an important epigenetic component, natural compounds that have the ability to regulate the epigenome become ideal candidates for study. Humans have a complex diet, which illustrates the need to elucidate the mechanisms of interaction between these bioactive compounds in combination. The natural compounds withaferin A (WA), from the Indian winter cherry, and sulforaphane (SFN), from cruciferous vegetables, have numerous anti-cancer effects and some report their ability to regulate epigenetic processes. Our study is the first to investigate the combinatorial effects of low physiologically achievable concentrations of WA and SFN on breast cancer cell proliferation, histone deacetylase1 (HDAC1) and DNA methyltransferases (DNMTs). No adverse effects were observed on control cells at optimal concentrations. There was synergistic inhibition of cellular viability in MCF-7 cells and a greater induction of apoptosis with the combinatorial approach than with either compound administered alone in both MDA-MB-231 and MCF-7 cells. HDAC expression was down-regulated at multiple levels. Lastly, we determined the combined effects of these bioactive compounds on the pro-apoptotic BAX and anti-apoptotic BCL-2 and found decreases in BCL-2 and increases in BAX. Taken together, our findings demonstrate the ability of low concentrations of combinatorial WA and SFN to promote cancer cell death and regulate key epigenetic modifiers in human breast cancer cells.