The present study was designed to investigate the chemopreventive properties of watercress, including whether watercress reduces cancer risk by inducing detoxification enzymes in a genotype-dependent manner. Watercress is a member of the cruciferous vegetables family, the consumption of which has been reported to reduce the risk of cancer. Proposed mechanisms include the inhibition of phase I and the induction of phase II enzymes. In the study, the in vitro and in vivo effects of watercress on chemopreventive parameters were studied using human peripheral blood mononuclear cells. Peripheral blood mononuclear cells were incubated either with a crude extract of fresh watercress (0.1–10 μL/mL with 8.2 g watercress per 1 mL extract) or with a key watercress compound, phenethyl isothiocyanate (1–10 μM), to conduct in vitro gene expression and enzyme activity experiments. In an additional in vivo intervention study, human subjects consumed 85 g watercress per day for eight weeks. Gene expression and glutathione S-transferase (GST) polymorphisms were determined in peripheral blood mononuclear cells obtained from the participants. The impact of watercress consumption on gene expression was assessed for detoxification enzymes such as superoxide dismutase 2 (SOD2) and glutathione peroxidase 1 (GPX1). The SOD and GPX activities in red blood cells were also analyzed with respect to glutathione S-transferase genotypes. Exposure of peripheral blood mononuclear cells to watercress extract or phenethyl isothiocyanate for 24 hours was found to markedly increase gene expression for both detoxification enzymes GPX1 (5.5-fold, 1 μL/mL watercress extract and 3.7-fold 1 μM phenethyl isothiocyanate) and SOD2 (12.1-fold, 10 μL/mL watercress extract and 7.3-fold, 10 μM phenethyl isothiocyanate). Watercress extract also increased SOD2 activity 1.9-fold. However, the watercress intervention experiment with human subjects produced no significant effects overall on peripheral blood mononuclear cell gene expression since high individual variations were found. However, for GSTM1*0 (but not GSTM1*1) individuals, a small but significant increase in GPX (p = 0.025) and SOD enzyme activity (p = 0.054) in red blood cells was observed (the GSTT1 genotype had no impact). The authors conclude that watercress is able to modulate the enzymes SOD and GPX in blood cells in vitro and in vivo. They further suggest that the capacity of moderate intake of cruciferous vegetables to induce detoxification is partly dependent on the GSTM1 genotype.

The present study was designed to investigate how histone deacetylase (HDAC) inhibition affects tamoxifen-induced autophagy in breast cancer cells. Autophagy is a type of cell self-digestion which can stop normal cells from developing into cancer cells and lead to cell death. However, autophagy can also protect breast cancer cells by neutralizing the effectiveness of anticancer drugs. Most patients with estrogen receptor-positive (ER+) breast cancer who experience an initial response to tamoxifen or aromatase inhibitors eventually develop resistance. In fact, many breast tumors are resistant to anti-estrogens from the outset of treatment. One of the known survival strategies of breast cancer cells treated with hormone therapy is the induction of autophagy. During autophagy, cellular components are catabolized in autophagic lysosomes, enabling the removal of damaged organelles and recycling of nutrients during periods of starvation. Treatment with both aromatase inhibitors and tamoxifen has been shown to be associated with upregulating expression of the essential autophagy protein beclin-1. Reduction of autophagy in breast cancer cells increases the cytotoxicity of tamoxifen, suggesting that autophagy in such cells is oncogenic and that autophagy is a potential contributor to tamoxifen resistance. The authors have demonstrated that the cytotoxicity of tamoxifen in breast cancer cells is enhanced by HDAC inhibitors, raising the possibility that HDAC inhibitors achieve synergy with tamoxifen by inhibiting autophagy. In the current study, several HDAC inhibitors were found to cause a synergistic increase in apoptosis and cell death in combination with tamoxifen. Adding an HDAC inhibitor to tamoxifen resulted in enhanced autophagy, in a time- and dose-dependent manner. However, HDAC inhibition promotes transition from autophagic cell preservation to apoptotic cell death. Functional estrogen-mediated signaling was found to be required for such increased autophagy; depletion of ER by siRNA or treatment with fulvestrant did not result in increased autophagy. The authors note that breast cancer cells react with an autophagic survival response as a result of nutrient starvation, tamoxifen treatment, and exposure to DNA damaging agents. The study findings further suggest that HDAC inhibitors act in synergy with tamoxifen to prevent the excess of autophagic lysosomes from sustaining self-preservation, thereby triggering elimination of cells by apoptotic cell death in a fatal switch. The authors conclude that combining tamoxifen with an HDAC inhibitor may represent a new therapeutic approach to overcome hormone therapy resistance.

Sulforaphane [1-isothiocyanato-4-(methylsulfinyl)butane] is an isothiocyanate in cruciferous vegetables with a number of potential chemopreventive actions. The current study examined the effects of sulforaphane on the proliferation of human MCF-7 breast cancer cells and on the expression of estrogen receptor α (ERα) protein and mRNA in the cells. Sulforaphane was found to inhibit cell proliferation and ERα protein expression. Lowered ERα expression was also found to be accompanied by decreased progesterone receptor expression. MCF-7 cell mRNA expression was inhibited by sulforaphane at relatively high doses, but not at low sulforaphane concentrations. The authors conclude that sulforaphane can inhibit proliferation of MCF-7 breast cancer cells and down-regulation of hormone receptor expression.

The present case-control population study investigated the independent and combined effects of Brassica vegetable intake and the GSTP1 Ile105Val genetic polymorphism on breast cancer risk. The study included 3,035 cases and 3,037 controls in the Shanghai Breast Cancer Study for whom diet and genetic data were available (87% of cases and 85% of controls). Cruciferous vegetables are the main dietary source of isothiocyanates and other glucosinolate derivatives that are known to induce phase II detoxifying enzymes, including glutathione S-transferases (GSTs). The GSTP1 Val/Val genotype was found to be significantly associated with greater risk of breast cancer (OR = 1.50; 95% CI: 1.12 - 1.99). The association was significantly higher in premenopausal women (OR = 1.69; 95% CI: 1.17- 2.43) than in postmenopausal women (OR = 1.20; 95% CI: 0.74-1.92). While total overall cruciferous vegetable consumption was not significantly associated with breast cancer risk, women reporting greater turnip and Chinese cabbage intakes were found to have a significantly lower postmenopausal breast cancer risk. Women with the GSTP1 Val/Val genotype and low cruciferous vegetable intake had a 1.74-times higher breast cancer risk than that of women with the Ile/Ile or Ile/Val genotype (95% CI: 1.13, 2.67). This association between low cruciferous vegetable intake and the Val/Val genotype was found predominantly among premenopausal women (OR = 2.08; 95% CI = 1.20, 3.59). The authors conclude that cruciferous vegetable intake may reduce breast cancer risk through high isothiocyanate exposure. Cruciferous vegetable consumption may also ameliorate the effects of the GSTP1 genotype.

The present study was designed to investigate the effects of broccoli (Brassica oleracea var. italica) and watercress (Rorripa nasturtium aquaticum) extracts in hormone receptor-negative MDA-MB-231 breast cancer cells. Aberrant overexpression of matrix metalloproteinases, including metalloproteinase-9, has been observed to be associated with increased invasive potential in cancer cells. In the study, the inhibitory effects of broccoli and watercress extracts on 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced cancer cell invasion and matrix metalloproteinase-9 activity were examined. Both extracts were found to suppress TPA-induced MMP-9 activity and invasiveness in a dose-dependent manner as determined by zymographic analysis. In addition, fractionation of individual extracts followed by liquid chromatography mass spectroscopy analysis showed that the inhibitory effects of each vegetable were associated with the presence of 4-methysulfinylbutyl (sulforaphane) and 7-methylsulphinylheptyl isothiocyanates. Taken together, the results indicate that isothiocyanates derived form broccoli and watercress suppress the invasive potential of human MDA-MB-231 breast cancer cells.

The current study was designed to evaluate the cytotoxicity of various organic brassica isothiocyanates in human breast cancer, mammary epithelium, and kidney cells. The isothiocyanates included 1-naphthyl isothiocyanate (NITC), benzyl isothiocyanate (BITC), ß-phenethyl isothiocyanate (PEITC), and sulforaphane. MCF-7/sensitive (wt) and MCF-7/Adr (which overexpresses P-glycoprotein) human breast cancer cells, as well as MCF-12A human mammary epithelium cells and a second human epithelial cell line, human kidney HK-2 cells, were used. The cytotoxicity of NITC, BITC, PEITC, and sulforaphane, as well as the cytotoxicity of the chemotherapeutic agents daunomycin and vinblastine, were assessed. Cell growth was measured using a sulforhodamine B assay. BITC and PEITC were found to inhibit the growth of human breast cancer cells and human mammary epithelium cells at concentrations similar to those of the chemotherapeutic drug daunomycin. Sulforaphane and NITC exhibited higher IC50 values. The authors conclude that the effects of these isothiocyanates on cell growth may translate into the suppression of the growth of preclinical tumors, and may indicate a potential use of these compounds as chemotherapeutic agents in cancer treatment.

Brassica vegetable (e.g., Chinese cabbage) consumption provides isothiocyanates (ITC) and other glucosinolate derivatives capable of inducing apoptosis, changing steroid hormone metabolism, regulating estrogen receptor response, and attenuating cellular proliferation. The present study investigated the rates of breast cancer in Shanghai, China, using urinary isothiocyanate (ITC) levels as a biological measure of glucosinolate intake. A representative subgroup of 337 cases providing presurgery, fasting, and first-morning urine specimens was matched by age, menopausal status, date of urine collection, and day of laboratory assay to population controls. Urinary ITC levels were found to be inversely related to breast cancer adjusted for age, menopausal status, soy protein, fibroadenoma history, family breast cancer, physical activity, waist-to-hip ratio, body mass index, age at menarche, and parity. This protective association was found in both premenopausal and postmenopausal women. In contrast, total brassica vegetable intake estimated from a food questionnaire was not found to be associated with breast cancer. The authors conclude that greater brassica vegetable consumption was associated with significantly reduced breast cancer risk among Chinese women.