The effect of low-dose radiation spillage during stereotactic radiosurgery for brain metastases on the development of de novo metastases.

PURPOSE/OBJECTIVES: Stereotactic radiosurgery (SRS) for metastatic disease to the brain is associated with higher in-brain failures compared to whole brain radiation therapy (WBRT). Here we investigated the relationship between low-dose fall off during SRS and location of new brain lesions. MATERIALS AND METHODS: One hundred sixty-seven patients treated with single fraction or fractionated SRS for intact or resected brain metastases at our institution from January 2016 to June 2018 were reviewed. Patients with imaging findings of new brain metastases after the initial SRS were included. Patients with WBRT before SRS were excluded. MRI scans for repeat treatments were fused with initial SRS plan. New lesions were outlined on the initial SRS planning CT. The mean dose that the site of new lesions received from initial SRS was tabulated. RESULTS: Thirty-eight patients met inclusion criteria. 165 new lesions were evaluated. There was a lower propensity to develop new brain lesions with increasing dose received by the regions from prior SRS, with 66%, 34%, 19%, 13%, 6%, 5%, 2% and 1% of new lesions appearing in regions that received less than 1 Gy, greater than or equal to 1, 2, 3, 4, 5, 6, and 7 Gy, respectively. Higher doses are received by smaller brain volumes during SRS. After accounting for volume, 14, 14, 11, 7, 2, 2, 1 and 1 new lesions appeared per 100 cm3 of brain in regions that received doses of less than 1 Gy, greater than or equal to 1, 2, 3, 4, 5, 6, and 7 Gy, respectively, from prior SRS. CONCLUSIONS: We identified low dose spillage during SRS to be associated with lower incidence of new brain metastases. Validation in larger dataset or prospective study of the combination of SRS with low dose WBRT would be crucial in order to establish causality of these findings.

Cardiac Irradiation Predicts Activity Decline in Patients Receiving Concurrent Chemoradiation for Locally Advanced Lung Cancer.

PURPOSE: Many patients with lung cancer are inactive due to their disease and underlying comorbidities, and activity levels can decline further during cancer therapy. Here we explore dosimetric predictors of activity decline in a cohort of patients who underwent continuous activity monitoring during definitive concurrent chemoradiotherapy (CRT) for locally advanced lung cancer. METHODS AND MATERIALS: We identified patients who participated in prospective clinical trials involving the use of a commercial fitness tracker throughout the course of CRT. For each patient, we applied linear regression to log-transformed daily step counts to compute the weekly rate of activity change from 1 week before radiation therapy (RT) initiation to 2 weeks after RT completion. Clinical and dosimetric factors were tested as predictors of activity change using linear regressions. RESULTS: Forty-six patient met the eligibility criteria. Median age was 66 years (range, 38-90). Pretreatment Eastern Cooperative Oncology Group performance status was 0, 1, and 2 for 17%, 70%, and 13%, respectively. Mean lung dose ranged from 5.0 to 23.5 Gy, mean esophagus dose from 1.1 to 39.6 Gy, and mean heart dose from 0.6 to 31.5 Gy. Median daily step count average was 5861 (interquartile range, 3540-8282) before RT and 3422 (interquartile range, 2364-5395) 2 weeks after RT completion. Rate of activity change was not significantly associated with age, performance status, or mean RT dose received by lungs or esophagus. In multivariate analysis, mean heart dose was significantly associated with rate of activity decline, with a 3.1% reduction in step count per week for every 10 Gy increase in mean heart dose (95% confidence interval: 0.5-5.7, P = .023). CONCLUSIONS: Extent of cardiac irradiation is associated with the rate of physical activity decline during CRT for lung cancer. Our novel finding contributes to the growing body of evidence that adverse effects of cardiac irradiation may be manifested at early time points.

Clinical characteristics and dose-volume histogram parameters associated with the development of pleural effusions in non-small cell lung cancer patients treated with chemoradiation therapy.

BACKGROUND: To investigate descriptive characteristics and dose metric (DM) parameters associated with development of pleural effusions (PlEf) in non-small cell lung cancer (NSCLC) treated with definitive chemoradiation therapy (CRT). MATERIALS AND METHODS: We retrospectively assessed treatment records and follow-up imaging of 66 NSCLC patients to identify PlEf formation after CRT. PlEf association between mean heart dose (MHD), mean lung dose (MLD), heart V5-V60 (HV), and lung V5-V60 (LV) were evaluated using Cox Proportional Hazard Models. RESULTS: A total of 52% (34 of 66 patients) of our population developed PlEf and the actuarial rates at 6 months, 12 months, and 18 months were 7%, 30%, and 42%, respectively. Median time to diagnosis was five months (range 0.06-27 months). The majority of PlEfs were grade one (67%) and developed at a median of four (0.06-13) months, followed by grade two (15%) at a median 11 (5-12) months, and grade three (18%) at a median of 11 (3-27) months. On multivariate analysis, increasing HV5-HV50, LV5-LV50, MHD, and MLD were associated with greater risk of PlEf. Higher grade PlEf was also associated with higher doses of radiation to the heart, while lung DM parameters were not significantly associated with higher PlEf grades. At five-months post-CRT, MHD of 25 Gy was associated with a 100% chance of grade one PlEf, an 82% risk of grade two PlEf, and a 19% risk of grade three PlEf. CONCLUSIONS: Post-CRT PlEf is common in NSCLC with the majority being grade one. Increasing heart and lung irradiation was associated with increased risk of PlEf. Increasing heart irradiation also correlated with development of increasing grades of PlEf. The impact of potential cardiopulmonary toxicity and resultant PlEfs after CRT requires additional study.

Dietary tocopherols inhibit cell proliferation, regulate expression of ERα, PPARγ, and Nrf2, and decrease serum inflammatory markers during the development of mammary hyperplasia.

Previous clinical and epidemiological studies of vitamin E have used primarily α-tocopherol for the prevention of cancer. However, γ-tocopherol has demonstrated greater anti-inflammatory and anti-tumor activity than α-tocopherol in several animal models of cancer. This study assessed the potential chemopreventive activities of a tocopherol mixture containing 58% γ-tocopherol (γ-TmT) in an established rodent model of mammary carcinogenesis. Female ACI rats were utilized due to their sensitivity to 17ß-estradiol (E2 ) to induce mammary hyperplasia and neoplasia. The rats were implanted subcutaneously with sustained release E2 pellets and given dietary 0.3% or 0.5% γ-TmT for 2 or 10 wk. Serum E2 levels were significantly reduced by the treatment with 0.5% γ-TmT. Serum levels of inflammatory markers, prostaglandin E2 and 8-isoprostane, were suppressed by γ-TmT treatment. Histology of mammary glands showed evidence of epithelial hyperplasia in E2 -treated rats. Immunohistochemical analysis of the mammary glands revealed a decrease in proliferating cell nuclear antigen (PCNA), cyclooxygenase-2 (COX-2), and estrogen receptor α (ERα), while there was an increase in cleaved-caspase 3, peroxisome proliferator-activated receptor γ (PPARγ), and nuclear factor (erythroid-derived 2)-like 2 (Nrf2) in γ-TmT-treated rats. In addition, treatment with γ-TmT resulted in a decrease in the expression of ERα mRNA, whereas mRNA levels of ERß and PPARγ were increased. In conclusion, γ-TmT was shown to suppress inflammatory markers, inhibit E2 -induced cell proliferation, and upregulate PPARγ and Nrf2 expression in mammary hyperplasia, suggesting that γ-TmT may be a promising agent for human breast cancer prevention.

Combination of atorvastatin with sulindac or naproxen profoundly inhibits colonic adenocarcinomas by suppressing the p65/ß-catenin/cyclin D1 signaling pathway in rats.

Evidence supports the protective role of nonsteroidal anti-inflammatory drugs (NSAID) and statins against colon cancer. Experiments were designed to evaluate the efficacies atorvastatin and NSAIDs administered individually and in combination against colon tumor formation. F344 rats were fed AIN-76A diet, and colon tumors were induced with azoxymethane. One week after the second azoxymethane treatment, groups of rats were fed diets containing atorvastatin (200 ppm), sulindac (100 ppm), naproxen (150 ppm), or their combinations with low-dose atorvastatin (100 ppm) for 45 weeks. Administration of atorvastatin at 200 ppm significantly suppressed both adenocarcinoma incidence (52% reduction, P = 0.005) and multiplicity (58% reduction, P = 0.008). Most importantly, colon tumor multiplicities were profoundly decreased (80%-85% reduction, P < 0.0001) when given low-dose atorvastatin with either sulindac or naproxen. Also, a significant inhibition of colon tumor incidence was observed when given a low-dose atorvastatin with either sulindac (P = 0.001) or naproxen (P = 0.0005). Proliferation markers, proliferating cell nuclear antigen, cyclin D1, and ß-catenin in tumors of rats exposed to sulindac, naproxen, atorvastatin, and/or combinations showed a significant suppression. Importantly, colon adenocarcinomas from atorvastatin and NSAIDs fed animals showed reduced key inflammatory markers, inducible nitric oxide synthase and COX-2, phospho-p65, as well as inflammatory cytokines, TNF-α, interleukin (IL)-1ß, and IL-4. Overall, this is the first report on the combination treatment using low-dose atorvastatin with either low-dose sulindac or naproxen, which greatly suppress the colon adenocarcinoma incidence and multiplicity. Our results suggest that low-dose atorvastatin with sulindac or naproxen might potentially be useful combinations for colon cancer prevention in humans.

A novel Gemini vitamin D analog represses the expression of a stem cell marker CD44 in breast cancer.

CD44 is a multifunctional transmembrane protein involved in cell proliferation, angiogenesis, invasion, and metastasis. CD44 is identified as a cancer stem cell marker, and the CD44-positive breast cancer cells are enriched in residual breast cancer cell populations after conventional therapies, suggesting that CD44 may be an important target for cancer prevention and therapy. Therefore, we investigated for the inhibitory effect of a novel Gemini vitamin D analog, 1α,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol (BXL0124), on mammary tumor growth and CD44 expression in MCF10DCIS.com human breast cancer in vitro and in vivo. MCF10DCIS.com cells were injected into mammary fat pads in immunodeficient mice, and BXL0124 was then administered intraperitoneally (0.1 µg/kg body weight) or orally (0.03 or 0.1 µg/kg body weight) 6 days a week for 5 weeks. At necropsy, mammary tumors and blood were collected for evaluating tumor growth, CD44 expression, and serum calcium level. BXL0124 suppressed mammary tumor growth and markedly decreased the expression of CD44 protein in MCF10DCIS xenograft tumors without causing hypercalcemic toxicity. BXL0124 also inhibited the expression of CD44 protein and mRNA as well as the transcriptional activity of the CD44 promoter in cultured MCF10DCIS.com cells. The repression of CD44 expression induced by BXL0124 was blocked by siRNA vitamin D receptor (VDR), indicating that the regulation of CD44 expression by BXL0124 is a VDR-dependent event. The novel Gemini vitamin D analog, BXL0124, represses CD44 expression in MCF10DCIS.com cells in vitro and in xenograft tumors, suggesting an inhibitory role of a Gemini vitamin D derivative on breast cancer stem cells.

Synthesis and biological evaluation of retinoid-chalcones as inhibitors of colon cancer cell growth.

Based on the observed anticancer activity of chalcones and retinoids, a novel class of retinoid-chalcone hybrids was designed and synthesized. As part of our ongoing studies to discover natural product based anticancer compounds, the retinoid-chalcone hybrids were tested against the colon cancer cell line HT-29. Retinoid like moiety was introduced through Friedel-Crafts alkylation of toluene. Among the synthesized compounds, the cyano derivative (E)-3-(3-oxo-3-(3,5,5,8,8-pentamethyl-5,6,7,8-tetrahydronaphthalen-2-yl)prop-1-enyl)benzonitrile 8 showed submicromolar inhibitory activity with an IC(50) of 0.66 µM.

In vitro and in vivo studies on stilbene analogs as potential treatment agents for colon cancer.

Based on the potential of resveratrol as a colon cancer chemopreventive agent, a set of 26 stilbenes were synthesized and tested against the colon cancer cell lines HT-29 and Caco-2. (Z)-4-(3,5-Dimethoxystyryl)aniline (4), (Z)-methyl-4-(3,5-dimethoxystyryl)benzoate (6), and (Z)-1,3-dimethoxy-5-(4-methoxystyryl)benzene (10) showed strong inhibitory activity in vitro. In vivo studies using HT-29 xenografts in immunodeficient mice were conducted with 4, 6 and 10, together with their corresponding trans isomers (3, 5, and 9, respectively), at the dose of 10 mg/kg body weight. Tumor volume was significantly lowered in 3-, 4-, and 9-treated groups. The cis- and trans-amino analogs (4 and 3, respectively) had similar effect on tumor growth, a 40% decrease compared to the control. Analysis of the serum revealed that 4 isomerized to 3, which may explain their similar effects in SCID mice. Stilbenes 5, 6, 9, and 10 retained their configurations in the serum. Stilbenes 6 and 10 lacked tumor-suppressive effect in SCID mice; the serum levels of these analogs were low (18.8 and 15.5 ng/mL, respectively). Stilbene 9, while weakly active in vitro demonstrated good activity in vivo, was found at higher levels in the serum (69.9 ng/mL) compared to 10. The anti-tumorigenic activity of these stilbene analogs may be partly linked to their effects on proteins involved in cell proliferation, as observed by lowered expression of proliferating cell nuclear antigen and upregulation of the cyclin-dependent kinase inhibitor, p27, in the tumor tissues. Overall, identification of the anti-tumorigenic potential of these compounds provides opportunities for their use against colorectal cancer.

Gemini vitamin D analog suppresses ErbB2-positive mammary tumor growth via inhibition of ErbB2/AKT/ERK signaling.

Numerous synthetic vitamin D analogs have been studied for their effects on the prevention and treatment of breast cancer. However, the inhibitory effects of naturally occurring 1alpha,25-dihydroxyvitamin D3 or its synthetic analogs on ErbB2 overexpressing mammary tumorigenesis have not been reported. Gemini vitamin D analogs are novel synthetic vitamin D derivatives with a unique structure of two six-carbon chains at C-20. We have previously shown that Gemini vitamin D analogs significantly inhibited carcinogen-induced estrogen receptor (ER)-positive mammary tumorigenesis and reduced ER-negative MCF10DCIS.com xenograft tumor growth without hypercalcemic toxicity. In the present study, we have determined the inhibitory effect of a potent Gemini vitamin D analog BXL0124 (1alpha,25-dihydroxy-20R-21(3-hydroxy-3-deuteromethyl-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-cholecalciferol) on the ErbB2/Her-2/neu overexpressing mammary tumorigenesis. The Gemini BXL0124 inhibits ErbB2-positive mammary tumor growth and down-regulates the phosphorylation of ErbB2, ERK and AKT in tumors of MMTV-ErbB2/neu transgenic mice. These effects of Gemini BXL0124 in vivo were confirmed by using the ErbB2 overexpressing tumor cells derived from the mammary tumors of MMTV-ErbB2/neu mice. In conclusion, the Gemini vitamin D analog BXL0124 inhibits the growth of ErbB2 overexpressing mammary tumors through regulating the ErbB2/AKT/ERK signaling pathways, suggesting that Gemini vitamin D analog may be considered for translational studies.

Dietary intake of pterostilbene, a constituent of blueberries, inhibits the beta-catenin/p65 downstream signaling pathway and colon carcinogenesis in rats.

Stilbenes are phytochemicals present in grapes, berries, peanuts and red wine. A widely studied stilbene, resveratrol (trans-3,5,4'-trihydroxystilbene), has been shown to exert antioxidant, anti-inflammatory, chemopreventive and antiaging effects in a number of biological systems. We reported earlier that pterostilbene (trans-3,5-dimethoxy-4'-hydroxystilbene), a structurally related stilbene found in blueberries, was effective in reducing the incidence and multiplicity of aberrant crypt foci formation in the colon of rats injected with azoxymethane (AOM). Our present study was to identify the chemopreventive potential of pterostilbene with colonic tumor formation as an end point and further to evaluate the mechanistic action of pterostilbene during colon carcinogenesis. F344 rats were given two AOM injections subcutaneously when they were 7 and 8 weeks old and continuously fed the control or 40 p.p.m. pterostilbene diet for 45 weeks. Overall analyses indicated that pterostilbene reduced colon tumor multiplicity of non-invasive adenocarcinomas, lowered proliferating cell nuclear antigen and downregulated the expression of beta-catenin and cyclin D1. Pterostilbene decreased mucosal levels of the proinflammatory cytokines, tumor necrosis factor-alpha, interleukin (IL)-1beta and IL-4. Colon tumors from pterostilbene-fed animals showed reduced expression of inflammatory markers as well as nuclear staining for phospho-p65, a key molecule in the nuclear factor-kappaB pathway. In HT-29 cells, pterostilbene reduced the protein levels of beta-catenin, cyclin D1 and c-MYC, altered the cellular localization of beta-catenin and inhibited the phosphorylation of p65. Our data with pterostilbene in suppressing colon tumorigenesis, cell proliferation as well as key inflammatory markers in vivo and in vitro suggest the potential use of pterostilbene for colon cancer prevention.

Mixed tocopherols prevent mammary tumorigenesis by inhibiting estrogen action and activating PPAR-gamma.

PURPOSE: Tocopherols are lipophilic antioxidants present in vegetable oils. Although the antioxidant and anticancer activities of alpha-tocopherol (vitamin E) have been studied for decades, recent intervention studies with alpha-tocopherol have been negative for protection from cancer in humans. The tocopherols consist of four isoforms, which are the alpha, beta, gamma, and delta variants, and recent attention is being given to other isoforms. In the present study, we investigated the inhibitory effect of a tocopherol mixture rich in gamma- and delta-tocopherols against mammary tumorigenesis. EXPERIMENTAL DESIGN: Female Sprague Dawley rats were treated with N-methyl-N-nitrosourea (NMU), and then fed diets containing 0.1%, 0.3%, or 0.5% mixed tocopherols rich in gamma- and delta-tocopherols for 9 weeks. Tumor burden and multiplicity were determined, and the levels of markers of inflammation, proliferation, and apoptosis were evaluated in the serum and in mammary tumors. The regulation of nuclear receptor signaling by tocopherols was studied in mammary tumors and in breast cancer cells. RESULTS: Dietary administration of 0.1%, 0.3%, or 0.5% mixed tocopherols suppressed mammary tumor growth by 38%, 50%, or 80%, respectively. Tumor multiplicity was also significantly reduced in all three mixed tocopherol groups. Mixed tocopherols increased the expression of p21, p27, caspase-3, and peroxisome proliferator activated receptor-gamma, and inhibited AKT and estrogen signaling in mammary tumors. Our mechanistic study found that gamma- and delta-tocopherols, but not alpha-tocopherol, activated peroxisome proliferator activated receptor-gamma and antagonized estrogen action in breast cancer. CONCLUSION: The results suggest that gamma- and delta-tocopherols may be effective agents for the prevention of breast cancer.

Anti-inflammatory action of pterostilbene is mediated through the p38 mitogen-activated protein kinase pathway in colon cancer cells.

Oxidative/nitrosative stress and generation of proinflammatory cytokines are hallmarks of inflammation. Because chronic inflammation is implicated in several pathologic conditions in humans, including cancers of the colon, anti-inflammatory compounds may be useful chemopreventive agents against colon cancer. Stilbenes, such as resveratrol, have diverse pharmacologic activities, which include anti-inflammation, cancer prevention, a cholesterol-lowering effect, enhanced insulin sensitivity, and increased life span. We previously showed that pterostilbene (trans-3,5-dimethoxy-4'-hydroxystilbene), a structural analogue of resveratrol, is present in blueberries and that pterostilbene inhibited expression of certain inflammation-related genes in the colon and suppressed aberrant crypt foci formation in rats. Here, we examined molecular mechanisms of the action of pterostilbene in colon cancer. Pterostilbene reduced cell proliferation, down-regulated the expression of c-Myc and cyclin D1, and increased the level of cleaved poly(ADP-ribose) polymerase. A combination of cytokines (tumor necrosis factor-alpha, IFN-gamma, and bacterial endotoxin lipopolysaccharide) induced inflammation-related genes such as inducible nitric oxide synthase and cyclooxygenase-2, which was significantly suppressed by treatment with pterostilbene. We further identified upstream signaling pathways contributing to the anti-inflammatory activity of pterostilbene by investigating multiple signaling pathways, including nuclear factor-kappaB, Janus-activated kinase-signal transducer and activator of transcription, extracellular signal-regulated kinase, p38, c-Jun NH(2)-terminal kinase, and phosphatidylinositol 3-kinase. Cytokine induction of the p38-activating transcription factor 2 pathway was markedly inhibited by pterostilbene among the different mediators of signaling evaluated. By silencing the expression of the p38 alpha isoform, there was significant reduction in cytokine induction of inducible nitric oxide synthase and cyclooxygenase-2. Our data suggest that the p38 mitogen-activated protein kinase cascade is a key signal transduction pathway for eliciting the anti-inflammatory action of pterostilbene in cultured HT-29 colon cancer cells.

Gemini vitamin D analogues inhibit estrogen receptor-positive and estrogen receptor-negative mammary tumorigenesis without hypercalcemic toxicity.

Numerous preclinical, epidemiologic, and clinical studies have suggested the benefits of vitamin D and its analogues for the prevention and treatment of cancer. However, the hypercalcemic effects have limited the use of 1alpha,25(OH)(2)D(3), the hormonally active form of vitamin D. To identify vitamin D analogues with better efficacy and low toxicity, we have tested >60 novel Gemini vitamin D analogues with a unique structure of two side chains for growth inhibition of breast cancer cells. Our initial studies found that some Gemini analogues are 5-15 times more active than 1alpha,25(OH)(2)D(3) in growth inhibition assay. In vivo experiments were designed to study the inhibitory effect of selected Gemini vitamin D analogues against mammary carcinogenesis by using (a) an N-methyl-N-nitrosourea-induced estrogen receptor (ER)-positive mammary tumor model and (b) an MCF10DCIS.com xenograft model of ER-negative mammary tumors. Among vitamin D analogues we tested, Gemini 0072 [1alpha,25-dihydroxy-20S-21(3-trideuteromethyl-3-hydroxy-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-19-nor-cholecalciferol] and Gemini 0097 [1alpha,25-dihydroxy-20R-21(3-trideuteromethyl-3-hydroxy-4,4,4-trideuterobutyl)-23-yne-26,27-hexafluoro-19-nor-cholecalciferol] administration inhibited by 60% the NMU-induced mammary tumor burden compared with the NMU-treated control group, but these compounds were devoid of hypercalcemia toxicity. In an ER-negative xenograft model, Gemini 0097 significantly suppressed tumor growth without hypercalcemia toxicity. We found that the inhibitory effect of Gemini 0097 was associated with an increased level of cyclin-dependent kinase inhibitor p21 and the insulin-like growth factor binding protein 3 in both ER-positive and ER-negative mammary tumors. Our results suggest that Gemini vitamin D analogues may be potent agents for the prevention and treatment of both ER-positive and ER-negative breast cancer without hypercalcemia toxicity.

Activation of bone morphogenetic protein signaling by a Gemini vitamin D3 analogue is mediated by Ras/protein kinase C alpha.

Bone morphogenetic proteins (BMP) are members of the transforming growth factor-beta superfamily, and they play an important role for embryonic development, for bone and cartilage formation, and during carcinogenesis. We have previously shown that the novel Gemini vitamin D(3) analogue, Ro-438-3582 [Ro3582; 1 alpha,25-dihydroxy-20S,21(3-hydroxy-3-methylbutyl)-23-yne-26,27-hexafluorocholecalciferol], inhibited cell proliferation and activated the BMP/Smad signaling pathway in MCF10AT1 breast epithelial cells. In this report, we investigated the upstream signaling pathways responsible for the activation of BMP/Smad signaling by Ro3582. Among seven different serine/threonine kinase inhibitors that we tested, protein kinase C (PKC) inhibitors blocked the effects of Ro3582 on the phosphorylation of Smad1/5, mRNA synthesis for BMP-2 and BMP-6, and cell growth in MCF10AT1 cells. Overexpression of PKC alpha, but not PKC epsilon, PKC delta or PKC zeta isoforms, increased Ro3582-induced phosphorylation of Smad1/5, suggesting that PKC alpha mediates the activation of Smad signaling and inhibition of cell proliferation. Interestingly, the activation of Smad signaling by Ro3582 was shown in Ha-ras-transfected MCF10AT1 cells, but not in the parent cell line (MCF10A without Ras). Inhibiting Ras activity blocked the translocation of PKC alpha to the plasma membrane and the phosphorylation of Smad1/5 induced by Ro3582, indicating that Ras is necessary for the activation of PKC alpha and Smad signaling. In conclusion, Ro3582 inhibits cell proliferation and activates BMP/Smad signaling via a Ras and PKC alpha pathway in breast epithelial cells.

Mixed tocopherols inhibit N-methyl-N-nitrosourea-induced mammary tumor growth in rats.

Tocopherols are present in significant amounts in vegetable oils used in human foods. The most prevalent tocopherols in foods are the alpha, beta, gamma, and delta variants with (RRR) stereochemistry. Tocopherols are lipophilic phenolic antioxidants, produced by plants. In the United States, gamma-tocopherol is the most prominent dietary tocopherol due to its high amount in the dominant commercially produced vegetable oils such as soybean, corn, and cottonseed. In this report, experiments were designed to study the inhibitory effect of mixed tocopherols against N-methyl-N-nitrosourea-induced mammary tumor growth in female Sprague-Dawley rats. Beginning at 21 days of age, rats were treated with a single intraperitoneal injection of 50 mg/kg body weight of N-methyl-N-nitrosourea. One wk later, the rats were fed experimental diets containing 0 or 0.1% mixed tocopherols containing over 50% gamma-tocopherol. At 9 wk after N-methyl-N-nitrosourea treatment, all rats were evaluated for inhibition of mammary tumor growth and proliferating cell nuclear antigen. Dietary administration of mixed tocopherols significantly suppressed mammary tumor growth (P < 0.05) and proliferating cell nuclear antigen (P < 0.01) and also moderately suppressed tumor multiplicity. The treatment increased the serum levels of gamma- and delta-tocopherols without affecting the body weight. The results of this study suggest that mixed tocopherols may be safe and effective agents for the prevention of breast cancer.

Pterostilbene, an active constituent of blueberries, suppresses aberrant crypt foci formation in the azoxymethane-induced colon carcinogenesis model in rats.

PURPOSE: Epidemiologic studies have linked the consumption of fruits and vegetables to reduced risk of several types of cancer. Laboratory animal model studies have provided evidence that stilbenes, phenolic compounds present in grapes and blueberries, play a role in inhibiting the risk of certain cancers. Pterostilbene, a naturally occurring stilbene from blueberries, was tested for its preventive activity against colon carcinogenesis. EXPERIMENTAL DESIGN: Experiments were designed to study the inhibitory effect of pterostilbene against the formation of azoxymethane-induced colonic aberrant crypt foci (ACF) preneoplastic lesions in male F344 rats. Beginning at 7 weeks of age, rats were treated with azoxymethane (15 mg/kg body weight s.c., once weekly for 2 weeks). One day after the second azoxymethane treatment, rats were fed experimental diets containing 0 or 40 ppm of pterostilbene. At 8 weeks after the second azoxymethane treatment, all rats were sacrificed, and colons were evaluated for ACF formation and for inhibition of inducible nitric oxide synthase (iNOS) and proliferating cell nuclear antigen. Effects on mucin MUC2 were also determined. RESULTS: Administration of pterostilbene for 8 weeks significantly suppressed azoxymethane-induced formation of ACF (57% inhibition, P < 0.001) and multiple clusters of aberrant crypts (29% inhibition, P < 0.01). Importantly, dietary pterostilbene also suppressed azoxymethane-induced colonic cell proliferation and iNOS expression. Inhibition of iNOS expression by pterostilbene was confirmed in cultured human colon cancer cells. CONCLUSIONS: The results of the present study suggest that pterostilbene, a compound present in blueberries, is of great interest for the prevention of colon cancer.