[Show abstract][Hide abstract] ABSTRACT: The molecular and biological heterogeneity of human breast cancer emphasizes the importance of a multitargeted approach for effective chemoprevention. Targeting the estrogen receptor pathway alone with the antiestrogens, Tamoxifen and Raloxifene reduces the incidence of estrogen receptor positive tumors but is ineffective against the development of hormone independent cancers. Our preclinical data indicate that the administration of omega-3 fatty acids potentiates the antitumor effects of Tamoxifen by inhibiting multiple proliferative and antiapoptotic pathways, several of which interact with estrogen receptor signaling. The complementarity in the mechanism of antitumor action of Tamoxifen and omega-3 fatty acids is well supported by our signaling, genomic, and proteomic studies. Furthermore, administration of omega-3 fatty acids allows the use of lower and, hence, likely less toxic doses of Tamoxifen. If these findings are supported in the clinical setting, the combination of omega-3 fatty acids and anteistrogens may emerge as a promising, effective, and safe chemopreventive strategy to be tested in a large multi-institutional trial using breast cancer incidence as the primary endpoint.
[Show abstract][Hide abstract] ABSTRACT: Few studies have explored the effects of omega-3 polyunsaturated fatty acid (n-3 PUFA) supplementation on immune modulation in murine models of mammary carcinogenesis. HER-2/neu and PyMT mice were randomized to 2 dietary interventions: AIN-93G-based diet with 1) 11% of diet (per gram weight) as corn oil (CO) or 2) 10% of diet as menhaden fish oil plus 1% of diet as corn oil (FO). FO significantly reduced the incidence and multiplicity of tumors (P < 0.001) in HER-2/neu, but not PyMT mice. FO-fed mice had significantly larger splenocyte counts than CO-fed mice in both the HER-2/neu and PyMT models; and in both models this was comprised of an increase in most cell types, including Gr-1(+)/CD11b(+) cells. T cells from FO-fed HER-2/neu mice produced significantly more interleukin-2 (P = 0.004) and interferon-γ (P = 0.012) in response to in vitro stimulation with anti-CD3 (0.5 µg/ml). Lastly, FO-fed HER-2/neu mice had significantly more tumor immune infiltrates than CO-fed mice, including NK1.1(+), F4/80(+), and Gr-1(+)/CD11b(+) cells (P ≤ 0.05). Greater Th1 cytokine production and significantly more tumor immune infiltrates in FO-fed Her2/neu mice may account for the cancer prevention effect of fish oil in this model.
Nutrition and Cancer 07/2015; 67(6):1-11. DOI:10.1080/01635581.2015.1060351 · 2.32 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Omega-3 polyunsaturated fatty acids (PUFAs) exert an anticancer effect by affecting multiple cellular mechanisms leading to inhibition of proliferation and induction of apoptosis. It is well known that breast cancer comprises distinct molecular subtypes which differ in their responsiveness to therapeutic and preventive agents. We tested the hypothesis that n-3FA may preferentially affect triple-negative breast cancer cells for which no targeted intervention is presently available. The in vitro antiproliferative effects of n-3 PUFA docosahexaenoic acid (DHA) and its metabolite, 4-OH-DHA as well as its putative metabolite 4-OXO-DHA, were tested in five triple-negative human basal breast cell lines at different stages of transformation (MCF-10F, trMCF, bsMCF, MDA-MB-231, and BT-549) and three luminal breast cancer cell lines (MCF-7, T-47D, and SK-BR-3). Cell proliferation was measured with the tetrazolium MTT (3-(4,5-dimethylthiazolyl-2)-2,5-diphenyltetrazolium bromide) assay. DHA and its oxidized derivatives significantly inhibited cell proliferation (20-90% reduction) of both basal and luminal breast cancer cell lines. The inhibitory effect was more pronounced on triple-negative basal breast cancer cell lines as compared to luminal breast cancer cell lines after 4-OXO-DHA treatment. Our data provide novel information regarding the preferential antitumor effect of oxidized derivatives of DHA on basal type breast cancer.
[Show abstract][Hide abstract] ABSTRACT: Percent breast density (PBD), a commonly used biomarker of breast cancer risk (BCR), is confounded by the influence of non-dense breast tissue on its measurement and factors, such as BMI, which have an impact on non-dense tissue. Consequently, BMI, a potent BCR factor, is, paradoxically, negatively correlated with PBD. We propose that absolute breast density (ABD) is a more accurate biomarker of BCR. We used a volumetric method to compare the correlation between PBD and ABD with baseline demographics and dietary and physical activity variables in a group of 169 postmenopausal women enrolled in a clinical trial prior to any intervention. As expected, a strong negative correlation between PBD and BMI was observed (Rho = -0.5, p < 5e(-12)). In contrast, we observed a strong, previously not well established, positive correlation of BMI with ABD (Rho = 0.41, p < 2.5e(-8)), which supports the use of ABD as a more accurate indicator of BCR. Correction of PBD by BMI did not frequently provide the same information as ABD. In addition, because of the strong influence of BMI on ABD, many correlations between dietary variables and ABD did not emerge, until adjustment was made for BMI. ABD corrected by BMI should be the gold standard BD measurement. These findings identify the optimal measurement of BD when testing the influence of an intervention on BD as a biomarker of BCR.
Breast Cancer Research and Treatment 06/2014; 146(2). DOI:10.1007/s10549-014-3031-6 · 3.94 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We used a proteomic approach to gain insights into the mechanisms of protection at the protein level by a high n-3:n-6 ratio in the absence and presence of Tamoxifen. Four groups were treated with 1-methyl-1-nitrosourea (MNU) and fed the following diets with varied n-3:n-6 ratios; Group 1 =1:1; Groups 2 and 3 =10:1 and 25:1, respectively; Group 4: (25:1) plus Tamoxifen(1 mg/kg diet). The plasma from 6 rats/group was pooled and analyzed with the isobaric Tags for Relative and Absolute Quantitation(iTRAQ) method; 148 proteins were identified with 95% confidence by ProteinPilot 4.0. In plasma of rats fed 10:1, 25:1 n-3:n-6, and 25:1 plus Tamoxifen the number of proteins that met our criteria(p≤0.05, error factor≤2) were 10, 14, and 19 proteins, respectively. Selected proteins were further validated by Western blotting. Compared to 1:1, both 10:1 and 25:1 diets up-regulated vitamin D binding protein, gelsolin, and 14-3-3 sigma, reported to have tumor suppressive effects, whereas A1BG, which has been reported to be elevated in the serum of breast cancer patients was decreased. Compared to 25:1, the 25:1 plus Tamoxifen diet down-regulated apolipoprotein E, haptoglobin, and ITIH4. Ingenuity Pathway Analysis determined that the trends of specific proteins were related to lipid metabolism in the 25:1 n-3:n-6 group, while the 25:1 n-3:n-6 plus Tamoxifen group included proteins involved in cancer and inflammation. Our results demonstrate that several proteins were altered in a manner consistent with chemoprevention; such proteins may serve as biomarkers to monitor efficacy of n-3 and Tamoxifen in future clinical chemoprevention trials.
Cancer Prevention Research 07/2013; 6(9). DOI:10.1158/1940-6207.CAPR-13-0152 · 4.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: Raloxifene is a 2nd-generation selective estrogen receptor modulator used for the prevention and treatment of osteoporosis and the prevention of breast cancer in postmenopausal women. Raloxifene is extensively metabolized by glucuronidation to form raloxifene-6-glucuronide (ral-6-Gluc) and raloxifene-4'-glucuronide (ral-4'-Gluc). The goal of the present study was to determine whether functional polymorphisms in active UGTs could play a role in altered raloxifene glucuronidation in vivo. Using homogenates from HEK293 UGT-overexpressing cell lines, raloxifene was shown to be glucuronidated primarily by the hepatic UGTs 1A1 and 1A9 and the extra-hepatic UGTs 1A8 and 1A10; no detectable raloxifene glucuronidation activity was found for UGT2B enzymes. Functional UGT1A1 transcriptional promoter genotypes were significantly (ptrend=0.005) associated with ral-6-Gluc formation in human liver microsomes, and, consistent with the decreased raloxifene glucuronidation activities observed in vitro with cell line over-expressing UGT1A8 variants, the UGT1A8*2 variant was significantly (p=0.023) correlated with total raloxifene glucuronide formation in human jejunum homogenates. While ral-4'-Gluc exhibited 1/100th the anti-estrogenic activity of raloxifene itself as measured by binding to the estrogen receptor, raloxifene glucuronides comprised ~99% of the circulating raloxifene dose in raloxifene-treated subjects, with ral-4'-Gluc comprising ~70% of raloxifene glucuronides. Plasma ral-6-Gluc (ptrend=0.0025), ral-4'-Gluc (ptrend=0.001), and total raloxifene glucuronides (ptrend=0.001) were increased in raloxifene-treated subjects who were predicted slow metabolizers [UGT1A8 (*1/*3)] vs intermediate metabolizers [UGT1A8 (*1/*1) or UGT1A8 (*1/*2)] vs fast metabolizers [UGT1A8 (*2/*2). These data suggest that raloxifene metabolism may be dependent on UGT1A8 genotype and that UGT1A8 genotype may play an important role in overall response to raloxifene.
Cancer Prevention Research 05/2013; 6(7). DOI:10.1158/1940-6207.CAPR-12-0448 · 4.44 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We have previously shown that a fish oil (FO)-rich diet increased the chemopreventive efficacy of tamoxifen (Tam) against N-methyl-N-nitrosourea (MNU)-induced rat mammary carcinogenesis. Herein, we provide evidence that Tam treatment modifies gene expression of mammary tumors depending upon the type of dietary fat fed to the animals. Rats initiated with MNU and treated with Tam were fed a diet rich in corn oil or FO. After 8 wk, cribriform tumors were collected and gene expression analysis was performed. Increased RNA expression of genes such as SerpinB10, Wisp2, and Apod in tumors from FO-treated rats is indicative of highly differentiated tumors. Decreased expression of H19 and Igf2 mRNA in Tam-treated groups, and Gamma Synuclein mRNA in the FO + Tam group may be related to tumor growth impairment and lower metastatic capacity. Change in the expression of genes associated with immunity in animals in the FO + Tam group may suggest a shift in the immune response. These data show that, although Tam modulates the expression of genes leading to tumor growth impairment, further modulations of genes are influenced by FO. FO modulation of Tam changes in gene expression accounts for its enhancing chemopreventive effect against MNU-induced mammary carcinogenesis. Supplemental materials are available for this article. Go to the publisher's online edition of Nutrition and Cancer to view the supplemental file.
Nutrition and Cancer 10/2012; 64(7):991-9. DOI:10.1080/01635581.2012.712736 · 2.32 Impact Factor