Prevention of Cancer

Clin CancerRes.2007 Jan 1;13(1):350-5.

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

Suh N¹,Paul S, Hao X, Simi B, Xiao H, Rimando AM, Reddy BS.

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Abstract

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 pterostilbeneagainst 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 pterostilbenefor 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 pterostilbenealso suppressed azoxymethane-induced colonic cell proliferation and iNOS expression. Inhibition of iNOS expression by pterostilbenewas confirmed in cultured human colon cancercells.

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.

PMID: 17200374

Carcinogenesis.2010 Jul;31(7):1272-8. doi: 10.1093/carcin/bgq004. Epub 2010 Jan 8.

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

Paul S¹, DeCastro AJ, Lee HJ, Smolarek AK, So JY, Simi B, Wang CX, Zhou R, Rimando AM, Suh N.

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Abstract

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.

PMID: 20061362

J Agric Food Chem.2010 Aug 11;58(15):8833-41. doi: 10.1021/jf101571z.

Pterostilbene inhibits colorectal aberrant crypt foci (ACF) and colon carcinogenesis via suppression of multiple signal transduction pathways in azoxymethane-treated mice.

Chiou YS¹, Tsai ML, Wang YJ, Cheng AC, Lai WM, Badmaev V, Ho CT, Pan MH.

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Abstract

Pterostilbene (PS), a natural dimethylated analogue of resveratrol, is known to have diverse pharmacologic activities including anticancer, anti-inflammation, antioxidant, apoptosis, antiproliferation, and analgesic potential. This paper reports the inhibitory effect of dietary administration of pterostilbene against the formation of azoxymethane (AOM)-induced colonic aberrant crypt foci (ACF) preneoplastic lesions and adenomas in male ICR mice and delineates its possible molecular mechanisms. ICR mice were given two AOM injections intraperitoneal and continuously fed a 50 or 250 ppm pterostilbene diet for 6 or 23 weeks. It was found that the dietary administration of pterostilbene effectively reduced AOM-induced formation of ACF and adenomas and inhibited the transcriptional activation of iNOS and COX-2 mRNA and proteins in mouse colon stimulated by AOM. Treatment with pterostilbene resulted in the induction of apoptosis in mouse colon. Moreover, administration of pterostilbene for 23 weeks significantly suppressed AOM-induced GSK3beta phosphorylation and Wnt/beta-catenin signaling. It was also found that pterostilbene significantly inhibited AOM-induced expression of VEGF, cyclin D1, and MMPs in mouse colon. Furthermore, pterostilbene markedly inhibited AOM-induced activation of Ras, phosphatidylinositol 3 kinase/Akt, and EGFR signaling pathways. All of these results revealed that pterostilbene is an effective antitumor agent as well as its inhibitory effect through the down-regulation of inflammatory iNOS and COX-2 gene expression and up-regulation of apoptosis in mouse colon, suggesting that pterostilbene is a novel functional agent capable of preventing inflammation-associated colon tumorigenesis.

PMID: 20681671

J Agric Food Chem.2011 Mar 23;59(6):2725-33. doi: 10.1021/jf2000103. Epub 2011 Feb 28.

Pterostilbene is more potent than resveratrol in preventing azoxymethane (AOM)-induced colon tumorigenesis via activation of the NF-E2-related factor 2 (Nrf2)-mediated antioxidant signaling pathway.

Chiou YS¹, Tsai ML, Nagabhushanam K, Wang YJ, Wu CH, Ho CT, Pan MH.

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Abstract

Inflammatory bowel diseases have been a risk factor of colorectal cancer (CRC). The reactive oxygen species (ROS) generated by inflammatory cells create oxidative stress and contribute to neoplastic transformation, proliferation, and even metastasis. Previously, resveratrol (RS) and pterostilbene (PS) had been reported to prevent chemical-induced colon carcinogenesis by anti-inflammatory and pro-apoptotic properties. In this study, we investigated whether RS and PS could prevent the azoxymethane (AOM)-induced colon tumorigenesis via antioxidant action and to explore possible molecular mechanisms. Male BALB/c mice were injected with AOM (5 mg/kg of body weight) with or without RS or PS, and at the end of the protocol, all of the mice were euthanized and colons were analyzed. Administrations of PS can be more effective than RS in reducing AOM-induced formation of aberrant crypt foci (ACF), lymphoid nodules (LNs), and tumors. We also find that PS is functioning more effectively than RS to reduce nuclear factor-κB (NF-κB) activation by inhibiting the phosphorylation of protein kinase C-β2 (PKC-β2) and decreasing downstream target gene expression, including inducible nitric oxide synthase (iNOS), cyclooxygenase-2 (COX-2), and aldose reductase (AR) in mouse colon stimulated by AOM. Moreover, administration of RS and PS for 6 weeks significantly enhanced expression of antioxidant enzymes, such as heme oxygenase-1 (HO-1) and glutathione reductase (GR), via activation of NF-E2-related factor 2 (Nrf2) signaling. When the above findings are taken together, they suggest that both stilbenes block cellular inflammation and oxidative stress through induction of HO-1 and GR, thereby preventing AOM-induced colon carcinogenesis. In comparison, PS was a more potent chemopreventive agent than RS for the prevention of colon cancer. This is also the first study to demonstrate that PS is a Nrf2 inducer and AR inhibitor in the AOM-treated colon carcinogenesis model.

PMID: 21355597

Asian Pac J CancerPrev.2012;13(12):6403-7.

Potential chemoprevention activity of pterostilbene by enhancing the detoxifying enzymes in the HT-29 cell line.

Harun Z¹, Ghazali AR.

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Abstract

Detoxifying enzymes are present in most epithelial cells of the human gastrointestinal tract where they protect against xenobiotics which may cause cancer. Induction of examples such as glutathione S-transferase (GST) and its thiol conjugate, glutathione (GSH) as well as NAD(P)H: quinoneoxidoreductase (NQO1) facilitate the excretion of carcinogens and thus preventing colon carcinogenesis. Pterostilbene, an analogue of resveratrol, has demonstrated numerous pharmacological activities linked with chemoprevention. This study was conducted to investigate the potential of pterostilbene as a chemopreventive agent using the HT-29 colon cancer cell line to study the modulation of GST and NQO1 activities as well as the GSH level. Initially, our group, established the optimum dose of 24 hours pterostilbene treatment using MTT assays. Then, effects of pterostilbene (0-50 μM) on GST and NQO1 activity and GSH levels were determined using GST, NQO1 and Ellman assays, respectively. MTT assay of pterostilbene (0-100 μM) showed no cytotoxicity toward the HT-29 cell line. Treatment increased GST activity in the cell line significantly (p<0.05) at 12.5 and 25.0 μM. In addition, treatment at 50 μM increased the GSH level significantly (p<0.05). Pterostilbene also enhanced NQO1 activity significantly (p<0.05) at 12.5 μM and 50 μM. Hence, pterostilbene is a potential chemopreventive agent capable of modulation of detoxifiying enzyme levels in HT-29 cells.

PMID: 23464466

J Agric Food Chem.2012 Jun 13;60(23):5693-708. doi: 10.1021/jf204084f. Epub 2012 Feb 22.

Influence of berry polyphenols on receptor signaling and cell-death pathways: implications for breast cancer prevention.

Aiyer HS¹, Warri AM, Woode DR, Hilakivi-Clarke L, Clarke R.

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Abstract

Breast cancer is the most commonly diagnosed cancer among women worldwide. Many women have become more aware of the benefits of increasing fruit consumption, as part of a healthy lifestyle, for the prevention of cancer. The mechanisms by which fruits, including berries, prevent breast cancer can be partially explained by exploring their interactions with pathways known to influence cell proliferation and evasion of cell-death. Two receptor pathways, estrogen receptor (ER) and tyrosine kinase receptors, especially the epidermal growth factor receptor (EGFR) family, are drivers of cell proliferation and play a significant role in the development of both primary and recurrent breast cancer. There is strong evidence to show that several phytochemicals present in berries such as cyanidin, delphinidin, quercetin, kaempferol, ellagic acid, resveratrol, and pterostilbene interact with and alter the effects of these pathways. Furthermore, they also induce cell death (apoptosis and autophagy) via their influence on kinase signaling. This review summarizes in vitro data regarding the interaction of berry polyphenols with the specific receptors and the mechanisms by which they induce cell death. This paper also presents in vivo data of primary breast cancer prevention by individual compounds and whole berries. Finally, a possible role for berries and berry compounds in the prevention of breast cancer and a perspective on the areas that require further research are presented.

PMID: 22300613

Food Funct.2012 Nov;3(11):1185-94. doi: 10.1039/c2fo30105a.

Pterostilbene, a natural analogue of resveratrol, potently inhibits 7,12-dimethylbenz[a]anthracene (DMBA)/12-O-tetradecanoylphorbol-13-acetate (TPA)-induced mouse skin carcinogenesis.

Tsai ML¹, Lai CS, Chang YH, Chen WJ, Ho CT, Pan MH.

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Abstract

We reported previously that pterostilbene, a natural analogue of resveratrol from blueberries, strongly suppressed lipopolysaccharide-induced up-expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in murine macrophages. In this study, we further investigated pterostilbene’s molecular mechanism of action and its anti-tumor properties. Pretreatment with pterostilbene has resulted in the reduction of 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced nuclear translocation of the nuclear factor-κB (NFκB) subunits. Pterostilbene also reduced TPA-induced phosphorylation of IκBα and p65 and caused subsequent degradation of IκBα. Moreover, pterostilbene markedly suppressed TPA-induced activation of extracellular signal-regulated kinase (ERK)1/2, p38 mitogen-activated protein kinase (MAPK), c-Jun N-terminal kinase (JNK)1/2, phosphatidylinositol 3-kinase (PI3K) and Akt, which are upstream of NFκB and activator protein 1 (AP-1). Furthermore, pterostilbene significantly inhibited 7,12-dimethylbenz[a]anthracene (DMBA)/TPA-induced skin tumor formation measured by the tumor multiplicity of papillomas at 20 weeks. The presented data has, for the first time, revealed that pterostilbene is an effective anti-tumor agent that functions by downregulating inflammatory iNOS and COX-2 gene expression in mouse skin. It is suggested that pterostilbene is a novel functional agent capable of preventing inflammation-associated tumorigenesis.

PMID: 22842666

J Agric Food Chem.2012 Nov 21;60(46):11533-41. doi: 10.1021/jf302778a. Epub 2012 Nov 7.

Chemopreventive effects of pterostilbene on urethane-induced lung carcinogenesis in mice via the inhibition of EGFR-mediated pathways and the induction of apoptosis and autophagy.

Chen RJ¹, Tsai SJ, Ho CT, Pan MH, Ho YS, Wu CH, Wang YJ.

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Abstract

Lung cancer is the most commonly diagnosed cancer and the leading cause of cancer deaths globally. Due to the lack of successful chemopreventive agents for lung cancer, there is an emerging need to evaluate new and effective agents for lung cancer prevention. Pterostilbene, a naturally occurring analogue of resveratrol, has been reported to be an effective chemopreventive agent against many cancers. The aim of this study is to investigate the chemopreventive effects of pterostilbene in urethane-induced murine lung tumors. Pretreatment with pterostilbene at 50 or 250 mg/kg significantly reduced tumor multiplicity by 26 and 49%, respectively. Pterostilbene also significantly inhibited tumor volume by 25 and 34% and decreased the tumor burden per mouse by 45 and 63%, respectively. The mechanisms by which pterostilbene suppresses lung tumorigenesis have been investigated in lung tissues and homogenates. The results indicate that the pterostilbene-mediated chemopreventive effects in vivo were a result of the inhibition of epidermal growth factor receptor (EGFR) and its downstream pathways, leading to retarded cell cycle progression, and of the induction of apoptosis and autophagy during urethane-induced lung tumorigenesis.

PMID: 23113763

Free Radic Biol Med.2015 Aug;85:1-11. doi: 10.1016/j.freeradbiomed.2015.03.027. Epub 2015 Apr 4.

Topical treatment with pterostilbene, a natural phytoalexin, effectively protects hairless mice against UVB radiation-induced skin damage and carcinogenesis.

Sirerol JA¹,Feddi F², Mena S¹, Rodriguez ML¹, Sirera P¹, Aupí M¹, Pérez S¹, Asensi M³, Ortega A³, Estrela JM⁴.

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Abstract

The aim of our study was to investigate in the SKH-1 hairless mouse model the effect of pterostilbene(Pter), a natural dimethoxy analog of resveratrol (Resv), against procarcinogenic ultraviolet B radiation (UVB)-induced skin damage. Pter prevented acute UVB (360 mJ/cm(2))-induced increase in skin fold, thickness, and redness, as well as photoaging-associated skin wrinkling and hyperplasia. Pter, but not Resv, effectively prevented chronic UVB (180 mJ/cm(2), three doses/week for 6 months)-induced skin carcinogenesis (90% of Pter-treated mice did not develop skin carcinomas, whereas a large number of tumors were observed in all controls). This anticarcinogenic effect was associated with (a) maintenance of skin antioxidant defenses (i.e., glutathione (GSH) levels, catalase, superoxide, and GSH peroxidase activities) close to control values (untreated mice) and (b) an inhibition of UVB-induced oxidative damage (using as biomarkers 8-hydroxy-2′-deoxyguanosine, protein carbonyls, and isoprostanes). The molecular mechanism underlying the photoprotective effect elicited by Pter was further evaluated using HaCaT immortalized human keratinocytes and was shown to involve potential modulation of the Nrf2-dependent antioxidant response.

KEYWORDS: Free radicals; Oxidative stress; Photocarcinogenesis; Phytochemicals; Polyphenols; Pterostilbene; Resveratrol; Skin damage; Stilbenes; UV radiation

PMID: 25845487

Food Chem Toxicol.2017 Jan;99:182-189. doi: 10.1016/j.fct.2016.11.007. Epub 2016 Nov 9.

Enhanced chemoprevention by the combined treatment of pterostilbeneand lupeol in B[a]P-induced mouse skin tumorigenesis.

Singh P¹,Arora D¹, Shukla Y².

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Abstract

The present study is aimed to evaluate the inhibitory effect of the combination of two phytochemicals; pterostilbeneand lupeol (generally obtained from blue berries, grapes, white cabbage, green pepper, olive and mangoes) on mouse skin tumorigenesis. We hypothesized that the concomitant topical treatment of selected phytochemicals would lead to improved impediment of skin cancer. Swiss albino mice (n = 25) received a topical dose of Benzo[a]pyrene (B[a]P, 5 μg/animal) with pre/post application of pterostilbene(16 μM/0.2 ml acetone/animal) and/or lupeol (500 μM/0.2 ml acetone/animal) for 32 weeks. Results showed that pterostilbeneand/or lupeol treatment resulted in a significant delay in onset of tumorigenesis. However, a more promising effect on tumor suppression was noted with the combination of both the phytochemicals. A significant reduction in average tumor volume, cumulative number of tumors and tumor multiplicity was recorded in combination treated group. The histopathological analysis illustrated the marked suppression in epidermal hyperplasia and necrotic cells in combination treated groups. Our study suggests that the combination of pterostilbeneand lupeol was more effective in prevention of skin canceras compared to either of the phytochemical alone. Therefore, the combined treatment of phytochemicals has better potential to prevent skin carcinogenesis.

KEYWORDS: Benzo[a]pyrene; Chemoprevention; Lupeol; Phytochemical; Pterostilbene

PMID: 27836749