Showing papers in "Cancer Prevention Research in 2010"

Metformin and Cancer Risk in Diabetic Patients: A Systematic Review and Meta-analysis

Abstract: Metformin, an insulin-lowering agent, has been associated with decreased cancer risk in epidemiologic studies in diabetic patients. We performed a comprehensive literature search and meta-analysis of epidemiologic studies to assess the effect of metformin on cancer incidence and mortality in diabetic patients, using Pubmed, ISI Web of Science, Embase, and the Cochrane library until May 2009, with no language or time restrictions. Independent reports with sufficient information to allow risk estimation of cancer risk/mortality and a measure of uncertainty were reviewed and cross-checked independently by three investigators. Eleven studies were selected for relevance in terms of intervention, population studied, independence, and reporting of cancer incidence or mortality data, reporting 4,042 cancer events and 529 cancer deaths. A 31% reduction in overall summary relative risk (0.69; 95% confidence interval, 0.61-0.79) was found in subjects taking metformin compared with other antidiabetic drugs. The inverse association was significant for pancreatic and hepatocellular cancer, and nonsignificant for colon, breast, and prostate cancer. A trend to a dose-response relationship was noted. Metformin is associated with a decreased risk of cancer incidence compared with other treatments among diabetic patients. Given the retrospective nature of most studies and the possibility that the control treatments increase risk, phase II trials are needed before large cancer prevention trials are launched.

Update of the National Surgical Adjuvant Breast and Bowel Project Study of Tamoxifen and Raloxifene (STAR) P-2 Trial: Preventing Breast Cancer

Abstract: The selective estrogen-receptor modulator (SERM) tamoxifen became the first U.S. Food and Drug Administration (FDA)-approved agent for reducing breast cancer risk but did not gain wide acceptance for prevention, largely because it increased endometrial cancer and thromboembolic events. The FDA approved the SERM raloxifene for breast cancer risk reduction following its demonstrated effectiveness in preventing invasive breast cancer in the Study of Tamoxifen and Raloxifene (STAR). Raloxifene caused less toxicity (versus tamoxifen), including reduced thromboembolic events and endometrial cancer. In this report, we present an updated analysis with an 81-month median follow-up. STAR women were randomly assigned to receive either tamoxifen (20 mg/d) or raloxifene (60 mg/d) for 5 years. The risk ratio (RR; raloxifene:tamoxifen) for invasive breast cancer was 1.24 (95% confidence interval [CI], 1.05-1.47) and for noninvasive disease, 1.22 (95% CI, 0.95-1.59). Compared with initial results, the RRs widened for invasive and narrowed for noninvasive breast cancer. Toxicity RRs (raloxifene:tamoxifen) were 0.55 (95% CI, 0.36-0.83; P = 0.003) for endometrial cancer (this difference was not significant in the initial results), 0.19 (95% CI, 0.12-0.29) for uterine hyperplasia, and 0.75 (95% CI, 0.60-0.93) for thromboembolic events. There were no significant mortality differences. Long-term raloxifene retained 76% of the effectiveness of tamoxifen in preventing invasive disease and grew closer over time to tamoxifen in preventing noninvasive disease, with far less toxicity (e.g., highly significantly less endometrial cancer). These results have important public health implications and clarify that both raloxifene and tamoxifen are good preventive choices for postmenopausal women with elevated risk for breast cancer.

Metformin prevents tobacco carcinogen--induced lung tumorigenesis.

Abstract: Activation of the mammalian target of rapamycin (mTOR) pathway is an important and early event in tobacco carcinogen-induced lung tumorigenesis, and therapies that target mTOR could be effective in the prevention or treatment of lung cancer. The biguanide metformin, which is widely prescribed for the treatment of type II diabetes, might be a good candidate for lung cancer chemoprevention because it activates AMP-activated protein kinase (AMPK), which can inhibit the mTOR pathway. To test this, A/J mice were treated with oral metformin after exposure to the tobacco carcinogen 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Metformin reduced lung tumor burden by up to 53% at steady-state plasma concentrations that are achievable in humans. mTOR was inhibited in lung tumors but only modestly. To test whether intraperitoneal administration of metformin might improve mTOR inhibition, we injected mice and assessed biomarkers in liver and lung tissues. Plasma levels of metformin were significantly higher after injection than oral administration. In liver tissue, metformin activated AMPK and inhibited mTOR. In lung tissue, metformin did not activate AMPK but inhibited phosphorylation of insulin-like growth factor-I receptor/insulin receptor (IGF-1R/IR), Akt, extracellular signal-regulated kinase (ERK), and mTOR. This suggested that metformin indirectly inhibited mTOR in lung tissue by decreasing activation of insulin-like growth factor-I receptor/insulin receptor and Akt upstream of mTOR. Based on these data, we repeated the NNK-induced lung tumorigenesis study using intraperitoneal administration of metformin. Metformin decreased tumor burden by 72%, which correlated with decreased cellular proliferation and marked inhibition of mTOR in tumors. These studies show that metformin prevents tobacco carcinogen-induced lung tumorigenesis and support clinical testing of metformin as a chemopreventive agent.

Metformin Suppresses Colorectal Aberrant Crypt Foci in a Short-term Clinical Trial

Abstract: The biguanide metformin is widely used for treating diabetes mellitus. We previously showed the chemopreventive effect of metformin in two rodent models of colorectal carcinogenesis. However, besides epidemiologic studies, little is known about the effects of metformin on human colorectal carcinogenesis. The objective of this pilot study was to evaluate the chemopreventive effect of metformin on rectal aberrant crypt foci (ACF), which are an endoscopic surrogate marker of colorectal cancer. We prospectively randomized 26 nondiabetic patients with ACF to treatment with metformin (250 mg/d, n = 12) or no treatment (control, n = 14); 23 patients were evaluable for end point analyses (9 metformin and 14 control); the two groups were similar in ACF number and other baseline clinical characteristics. Magnifying colonoscopy determined the number of rectal ACF in each patient at baseline and after 1 month in a blinded fashion (as were all laboratory end point analyses). We also examined proliferative activity in colonic epithelium (via proliferating cell nuclear antigen labeling index) and apoptotic activity (via terminal deoxynucleotidyl transferase dUTP nick-end labeling). At 1 month, the metformin group had a significant decrease in the mean number of ACF per patient (8.78 +/- 6.45 before treatment versus 5.11 +/- 4.99 at 1 month, P = 0.007), whereas the mean ACF number did not change significantly in the control group (7.23 +/- 6.65 versus 7.56 +/- 6.75, P = 0.609). The proliferating cell nuclear antigen index was significantly decreased and the apoptotic cell index remained unaltered in normal rectal epithelium in metformin patients. This first reported trial of metformin for inhibiting colorectal carcinogenesis in humans provides preliminary evidence that metformin suppresses colonic epithelial proliferation and rectal ACF formation in humans, suggesting its promise for the chemoprevention of colorectal cancer.

Resveratrol modulates drug- and carcinogen-metabolizing enzymes in a healthy volunteer study

Abstract: Resveratrol has been shown to exhibit cancer-preventive activities in preclinical studies. We conducted a clinical study to determine the effect of pharmacologic doses of resveratrol on drug- and carcinogen-metabolizing enzymes. Forty-two healthy volunteers underwent baseline assessment of cytochrome P450 (CYP) and phase II detoxification enzymes. CYP1A2, CYP2D6, CYP2C9, and CYP3A4 enzyme activities were measured by the metabolism of caffeine, dextromethorphan, losartan, and buspirone, respectively. Blood lymphocyte glutathione S-transferase (GST) activity and GST-pi level and serum total and direct bilirubin, a surrogate for UDP-glucuronosyl transferase (UGT) 1A1 activity, were measured to assess phase II enzymes. After the baseline evaluation, study participants took 1 g of resveratrol once daily for 4 weeks. Enzyme assessment was repeated upon intervention completion. Resveratrol intervention was found to inhibit the phenotypic indices of CYP3A4, CYP2D6, and CYP2C9 and to induce the phenotypic index of 1A2. Overall, GST and UGT1A1 activities were minimally affected by the intervention, although an induction of GST-pi level and UGT1A1 activity was observed in individuals with low baseline enzyme level/activity. We conclude that resveratrol can modulate enzyme systems involved in carcinogen activation and detoxification, which may be one mechanism by which resveratrol inhibits carcinogenesis. However, pharmacologic doses of resveratrol could potentially lead to increased adverse drug reactions or altered drug efficacy due to inhibition or induction of certain CYPs. Further clinical development of resveratrol for cancer prevention should consider evaluation of lower doses of resveratrol to minimize adverse metabolic drug interactions.

Metformin and Other Biguanides in Oncology: Advancing the Research Agenda

Abstract: Retrospective studies that may be impractical to confirm prospectively suggest that diabetics treated with metformin have a substantially reduced cancer burden compared with other diabetics. It is unclear if this reflects a chemopreventive effect, an effect on transformed cells, or both. It also remains to be established if these data have relevance to people without diabetes. Laboratory models, however, provide independent impressive evidence for the activity of metformin and other biguanides in both cancer treatment and chemoprevention. Investigations of mechanisms of action of biguanides have revealed considerable complexity and have identified important gaps in knowledge that should be addressed to ensure the optimal design of clinical trials of these agents. Such trials may define important new indications for biguanides in the prevention and/or treatment of many common cancers.

MicroRNA expression profiling of exfoliated colonocytes isolated from feces for colorectal cancer screening

Abstract: To reduce the colorectal cancer (CRC) mortality rate, we have reported several CRC screening methods using colonocytes isolated from feces. Expression analysis of oncogenic microRNA (miRNA) in peripheral blood was recently reported for CRC detection. In the present study, we conducted miRNA expression analysis of exfoliated colonocytes isolated from feces for CRC screening. Two hundred six CRC patients and 134 healthy volunteers were enrolled in the study. miRNA expression of the miR-17-92 cluster, miR-21, and miR-135 in colonocytes isolated from feces as well as frozen tissues was analyzed by quantitative real-time PCR. The expression of the miR-17-92 cluster, miR-21, and miR-135 was significantly higher in CRC tissues compared with normal tissues. The exfoliated colonocytes of 197 CRC patients and 119 healthy volunteers were analyzed because of the presence of sufficient miRNA concentration. miR-21 expression did not differ significantly between CRC patients and healthy volunteers (P = 0.6). The expression of miR-17-92 cluster and miR-135 was significantly higher in CRC patients than in healthy volunteers (P < 0.0001). The overall sensitivity and specificity by using miRNA expression was 74.1% (146/197; 95% confidence interval, 67.4-80.1) and 79.0% (94/119; 95% confidence interval, 70.6-85.9), respectively. Sensitivity was dependent only on tumor location (P = 0.0001). miRNA was relatively well conserved in exfoliated colonocytes from feces both of CRC patients and healthy volunteers. miRNA expression analysis of the isolated colonocytes may be a useful method for CRC screening. Furthermore, oncogenic miRNA highly expressed in CRC should be investigated for CRC screening tests in the future.

Resveratrol Suppresses Colitis and Colon Cancer Associated with Colitis

Abstract: Resveratrol is a naturally occurring polyphenol that exhibits pleiotropic health beneficial effects, including anti-inflammatory, cardio-protective, and cancer-protective activities. It is recognized as one of the more promising natural molecules in the prevention and treatment of chronic inflammatory and autoimmune disorders. Ulcerative colitis is an idiopathic, chronic inflammatory disease of the colon associated with a high colon cancer risk. Here, we used a dextran sulfate sodium (DSS) mouse model of colitis, which resembles human ulcerative colitis pathology. Resveratrol mixed in food ameliorates DSS-induced colitis in mice in a dose-dependent manner. Resveratrol significantly improves inflammation score, downregulates the percentage of neutrophils in the mesenteric lymph nodes and lamina propria, and modulates CD3(+) T cells that express tumor necrosis factor-alpha and IFN-gamma. Markers of inflammation and inflammatory stress (p53 and p53-phospho-Ser(15)) are also downregulated by resveratrol. Because chronic colitis drives colon cancer risk, we carried out experiments to determine the chemopreventive properties of resveratrol. Tumor incidence is reduced from 80% in mice treated with azoxymethane (AOM) + DSS to 20% in mice treated with AOM + DSS + resveratrol (300 ppm). Tumor multiplicity also decreased with resveratrol treatment. AOM + DSS-treated mice had 2.4 +/- 0.7 tumors per animal compared with AOM + DSS + 300 ppm resveratrol, which had 0.2 +/- 0.13 tumors per animal. The current study indicates that resveratrol is a useful, nontoxic complementary and alternative strategy to abate colitis and potentially colon cancer associated with colitis.

The origins and implications of intratumor heterogeneity.

Abstract: Human tumors often display startling intratumor heterogeneity in various features including histology, gene expression, genotype, and metastatic and proliferative potential. This phenotypic and genetic heterogeneity plays an important role in neoplasia, cancer progression, and therapeutic resistance. In this issue of the journal (beginning on page 1388), Merlo et al. report their use of molecular data from 239 patients with Barrett's esophagus to evaluate the propensity of major diversity indices for predicting progression to esophageal adenocarcinoma. This work helps elucidate the implications of molecular heterogeneity for the evolution of neoplasia.

Pomegranate ellagitannin-derived compounds exhibit antiproliferative and antiaromatase activity in breast cancer cells in vitro.

Abstract: Estrogen stimulates the proliferation of breast cancer cells and the growth of estrogen-responsive tumors. The aromatase enzyme, which converts androgen to estrogen, plays a key role in breast carcinogenesis. The pomegranate fruit, a rich source of ellagitannins (ET), has attracted recent attention due to its anticancer and antiatherosclerotic properties. On consumption, pomegranate ETs hydrolyze, releasing ellagic acid, which is then converted to 3,8-dihydroxy-6H-dibenzo[b,d]pyran-6-one (“urolithin”) derivatives by gut microflora. The purpose of this study was to investigate the antiaromatase activity and inhibition of testosterone-induced breast cancer cell proliferation by ET-derived compounds isolated from pomegranates. A panel of 10 ET-derived compounds including ellagic acid, gallagic acid, and urolithins A and B (and their acetylated, methylated, and sulfated analogues prepared in our laboratory) were examined for their ability to inhibit aromatase activity and testosterone-induced breast cancer cell proliferation. Using a microsomal aromatase assay, we screened the panel of ET-derived compounds and identified six with antiaromatase activity. Among these, urolithin B (UB) was shown to most effectively inhibit aromatase activity in a live cell assay. Kinetic analysis of UB showed mixed inhibition, suggesting more than one inhibitory mechanism. Proliferation assays also determined that UB significantly inhibited testosterone-induced MCF-7aro cell proliferation. The remaining test compounds also exhibited antiproliferative activity, but to a lesser degree than UB. These studies suggest that pomegranate ET–derived compounds have potential for the prevention of estrogen-responsive breast cancers. Cancer Prev Res; 3(1); 108–13. ©2010 AACR.

Effects of Cigarette Smoke on the Human Oral Mucosal Transcriptome

Abstract: Use of tobacco is responsible for approximately 30% of all cancer-related deaths in the United States, including cancers of the upper aerodigestive tract. In the current study, 40 current and 40 age- and gender-matched never smokers underwent buccal biopsies to evaluate the effects of smoking on the transcriptome. Microarray analyses were carried out using Affymetrix HGU133 Plus 2 arrays. Smoking altered the expression of numerous genes: 32 genes showed increased expression and 9 genes showed reduced expression in the oral mucosa of smokers versus never smokers. Increases were found in genes involved in xenobiotic metabolism, oxidant stress, eicosanoid synthesis, nicotine signaling, and cell adhesion. Increased numbers of Langerhans cells were found in the oral mucosa of smokers. Interestingly, smoking caused greater induction of aldo-keto reductases, enzymes linked to polycyclic aromatic hydrocarbon-induced genotoxicity, in the oral mucosa of women than men. Striking similarities in expression changes were found in oral compared with the bronchial mucosa. The observed changes in gene expression were compared with known chemical signatures using the Connectivity Map database and suggested that geldanamycin, a heat shock protein 90 inhibitor, might be an antimimetic of tobacco smoke. Consistent with this prediction, geldanamycin caused dose-dependent suppression of tobacco smoke extract-mediated induction of CYP1A1 and CYP1B1 in vitro. Collectively, these results provide new insights into the carcinogenic effects of tobacco smoke, support the potential use of oral epithelium as a surrogate tissue in future lung cancer chemoprevention trials, and illustrate the potential of computational biology to identify chemopreventive agents.

A comprehensive survey of clonal diversity measures in Barrett's esophagus as biomarkers of progression to esophageal adenocarcinoma

Abstract: Neoplastic progression is an evolutionary process driven by the generation of clonal diversity and natural selection on that diversity within a neoplasm. We hypothesized that clonal diversity is associated with risk of progression to cancer. We obtained molecular data from a cohort of 239 participants with Barrett's esophagus, including microsatellite shifts and loss of heterozygosity, DNA content tetraploidy and aneuploidy, methylation, and sequence mutations. Using these data, we tested all major diversity measurement methods, including genetic divergence and entropy-based measures, to determine which measures are correlated with risk of progression to esophageal adenocarcinoma. We also tested whether the use of different sets of loci and alterations to define clones (e.g., selectively advantageous versus evolutionarily neutral) improved the predictive value of the diversity indices. All diversity measures were strong and highly significant predictors of progression (Cox proportional hazards model, P < 0.001). The type of alterations evaluated had little effect on the predictive value of most of the diversity measures. In summary, diversity measures are robust predictors of progression to cancer in this cohort.

Resveratrol suppresses oxidative stress and inflammatory response in diethylnitrosamine-initiated rat hepatocarcinogenesis.

Abstract: Hepatocellular carcinoma (HCC), one of the most frequent and deadliest cancers, has been increasing considerably in the United States. In the absence of a proven effective therapy for HCC, novel chemopreventive strategies are urgently needed to lower the current morbidity and mortality of HCC. Recently, we have reported that resveratrol, a compound present in grapes and red wine, significantly prevents diethylnitrosamine (DENA)-induced liver tumorigenesis in rats, although the mechanism of action is not completely understood. In the present study, we have examined the underlying mechanisms of resveratrol chemoprevention of hepatocarcinogenesis by investigating the effects of resveratrol on oxidative damage and inflammatory markers during DENA-initiated rat liver carcinogenesis. There was a significant increase in hepatic lipid peroxidation and protein oxidation in carcinogen control animals compared with their normal counterparts at the end of the study (20 weeks). Elevated expressions of inducible nitric oxide synthase and 3-nitrotyrosine were noticed in the livers of the same animals. Dietary resveratrol (50-300 mg/kg) administered throughout the study reversed all the aforementioned markers in a dose-responsive fashion in rats challenged with DENA. Resveratrol also elevated the protein and mRNA expression of hepatic nuclear factor E2-related factor 2 (Nrf2). Results of the present investigation provide evidence that attenuation of oxidative stress and suppression of inflammatory response mediated by Nrf2 could be implicated, at least in part, in the chemopreventive effects of this dietary agent against chemically induced hepatic tumorigenesis in rats. The outcome of this study may benefit the development of resveratrol in the prevention and intervention of human HCC.

Factors affecting the decision of breast cancer patients to undergo contralateral prophylactic mastectomy.

Abstract: Increasing numbers of women with breast cancer are electing for contralateral prophylactic mastectomy (CPM) to reduce the risk of developing contralateral breast cancer. The objective of this study was to identify factors that may affect a patient's decision to undergo CPM. We identified 2,504 women with stage 0 to III unilateral primary breast cancer who underwent breast surgery at our institution from January 2000 to August 2006 from a prospectively maintained database. We did logistic regression analyses to determine which factors were associated with undergoing CPM. Of 2,504 breast cancer patients, 1,223 (48.8%) underwent total mastectomy. Of the 1,223 patients who underwent mastectomy, 284 (23.2%) underwent immediate or delayed CPM. There were 33 patients (1.3%) who had genetic testing before the surgery, with the use of testing increasing in the latter years of the study (0.1% in 2000-2002 versus 2.0% in 2003-2006; P < 0.0001). Multivariable analysis revealed several factors that were associated with a patient undergoing CPM: age younger than 50 years, white ethnicity, family history of breast cancer, BRCA1/2 mutation testing, invasive lobular histology, clinical stage, and use of reconstruction. We identified specific patient and tumor characteristics associated with the use of CPM. Although genetic testing is increasing, most women undergoing CPM did not have a known genetic predisposition to breast cancer. Evidence-driven models are needed to better inform women of their absolute risk of contralateral breast cancer as well as their competing risk of recurrence from the primary breast cancer to empower them in their active decision making.

Gene expression patterns in the human breast after pregnancy.

Abstract: Epidemiologic studies have established that pregnancy has a bidirectional, time-dependent effect on breast cancer risk; a period of elevated risk is followed by a long-term period of protection. The purpose of the present study was to determine whether pregnancy and involution are associated with gene expression changes in the normal breast, and whether such changes are transient or persistent. We examined the expression of a customized gene set in normal breast tissue from nulliparous, recently pregnant (0-2 years since pregnancy), and distantly pregnant (5-10 years since pregnancy) age-matched premenopausal women. This gene set included breast cancer biomarkers and genes related to immune/inflammation, extracellular matrix remodeling, angiogenesis, and hormone signaling. Laser capture microdissection and RNA extraction were done from formalin-fixed paraffin-embedded reduction mammoplasty and benign biopsy specimens and analyzed using real-time PCR arrays containing 59 pathway-specific and 5 housekeeping genes. We report 14 of 64 (22%) of the selected gene set to be differentially regulated (at P < 0.05 level) in nulliparous versus parous breast tissues. Based on gene set analysis, inflammation-associated genes were significantly upregulated as a group in both parous groups compared with nulliparous women ( P = 0.03). Moreover, parous subjects had significantly reduced expression of estrogen receptor α ( ERα, ESR1 ), progesterone receptor ( PGR ), and ERBB2 ( Her2/neu ) and 2-fold higher estrogen receptor-β ( ESR2 ) expression compared with nulliparous subjects. These initial data, among the first on gene expression in samples of normal human breast, provide intriguing clues about the mechanisms behind the time-dependent effects of pregnancy on breast cancer risk. Cancer Prev Res; 3(3); 301–11

Association between folate levels and CpG Island hypermethylation in normal colorectal mucosa.

Abstract: Gene-specific promoter methylation of several genes occurs in aging normal tissues and may predispose to tumorigenesis. In the present study, we investigate the association of blood folate levels and dietary and lifestyle factors with CpG island (CGI) methylation in normal colorectal mucosa. Subjects were enrolled in a multicenter chemoprevention trial of aspirin or folic acid for the prevention of large bowel adenomas. We collected 1,000 biopsy specimens from 389 patients, 501 samples from the right colon and 499 from the rectum at the follow-up colonoscopy. We measured DNA methylation of estrogen receptor alpha (ERα) and secreted frizzled related protein-1 (SFRP1), using bisulfite pyrosequencing. We used generalized estimating equations regression analysis to examine the association between methylation and selected variables. For both ERα and SFRP1, percentage methylation was significantly higher in the rectum than in the right colon (P = 0.001). For each 10 years of age, we observed a 1.7% increase in methylation level for ERα and a 2.9% increase for SFRP1 (P < 0.0001). African Americans had a significantly lower level of ERα and SFRP1 methylation than Caucasians and Hispanics. Higher RBC folate levels were associated with higher levels of both ERα (P = 0.03) and SFRP1 methylation (P = 0.01). Our results suggest that CGI methylation in normal colorectal mucosa is related to advancing age, race, rectal location, and RBC folate levels. These data have important implications regarding the safety of supplementary folate administration in healthy adults, given the hypothesis that methylation in normal mucosa may predispose to colorectal neoplasia.

Chemoprevention of Cigarette Smoke–Induced Alterations of MicroRNA Expression in Rat Lungs

Abstract: We previously showed that exposure to environmental cigarette smoke (ECS) for 28 days causes extensive downregulation of microRNA expression in the lungs of rats, resulting in the overexpression of multiple genes and proteins. In the present study, we evaluated by microarray the expression of 484 microRNAs in the lungs of either ECS-free or ECS-exposed rats treated with the orally administered chemopreventive agents N-acetylcysteine, oltipraz, indole-3-carbinol, 5,6-benzoflavone, and phenethyl isothiocyanate (as single agents or in combinations). This is the first study of microRNA modulation by chemopreventive agents in nonmalignant tissues. Scatterplot, hierarchical cluster, and principal component analyses of microarray and quantitative PCR data showed that none of the above chemopreventive regimens appreciably affected the baseline microRNA expression, indicating potential safety. On the other hand, all of them attenuated ECS-induced alterations but to a variable extent and with different patterns, indicating potential preventive efficacy. The main ECS-altered functions that were modulated by chemopreventive agents included cell proliferation, apoptosis, differentiation, Ras activation, P53 functions, NF-kappaB pathway, transforming growth factor-related stress response, and angiogenesis. Some microRNAs known to be polymorphic in humans were downregulated by ECS and were protected by chemopreventive agents. This study provides proof-of-concept and validation of technology that we are further refining to screen and prioritize potential agents for continued development and to help elucidate their biological effects and mechanisms. Therefore, microRNA analysis may provide a new tool for predicting at early carcinogenesis stages both the potential safety and efficacy of cancer chemopreventive agents.

Epidermal Growth Factor Receptor Expression and Gene Copy Number in the Risk of Oral Cancer

Abstract: Leukoplakia is the most common premalignant lesion of the oral cavity. Epidermal growth factor receptor (EGFR) abnormalities are associated with oral tumorigenesis and progression. We hypothesized that EGFR expression and gene copy number changes are predictors of the risk of an oral premalignant lesion (OPL) progressing to oral squamous cell carcinoma (OSCC). A formalin-fixed, paraffin-embedded OPL biopsy specimen was collected from each of 162 patients in a randomized controlled clinical trial. We assessed EGFR expression by immunohistochemistry with two methods: a semiquantitative analysis (145 evaluable specimens) and an automated quantitative analysis (127 evaluable specimens). EGFR gene copy number was assessed by fluorescence in situ hybridization (FISH) in a subset of 49 OPLs with high EGFR expression defined by the semiquantitative analysis. We analyzed EGFR abnormalities for associations with OSCC development. High EGFR expression occurred in 103 (71%) of the 145 OPLs and was associated with a nonsignificantly higher risk of OSCC (P = 0.10). Twenty (41%) of 49 OPLs assessed by FISH had an increased EGFR gene copy number (FISH-positive). Patients with FISH-positive lesions had a significantly higher incidence of OSCC than did patients with FISH-negative (a normal copy number) lesions (P = 0.0007). Of note, 10 of 11 OSCCs that developed at the site of the examined OPL were in the FISH-positive group, leaving only one FISH-negative OPL that did so (P

Meat Processing and Colon Carcinogenesis: Cooked, Nitrite-Treated, and Oxidized High-Heme Cured Meat Promotes Mucin-Depleted Foci in Rats

Abstract: Processed meat intake is associated with colorectal cancer risk, but no experimental study supports the epidemiologic evidence. To study the effect of meat processing on carcinogenesis promotion, we first did a 14-day study with 16 models of cured meat. Studied factors, in a 2 x 2 x 2 x 2 design, were muscle color (a proxy for heme level), processing temperature, added nitrite, and packaging. Fischer 344 rats were fed these 16 diets, and we evaluated fecal and urinary fat oxidation and cytotoxicity, three biomarkers of heme-induced carcinogenesis promotion. A principal component analysis allowed for selection of four cured meats for inclusion into a promotion study. These selected diets were given for 100 days to rats pretreated with 1,2-dimethylhydrazine. Colons were scored for preneoplastic lesions: aberrant crypt foci (ACF) and mucin-depleted foci (MDF). Cured meat diets significantly increased the number of ACF/colon compared with a no-meat control diet (P = 0.002). Only the cooked nitrite-treated and oxidized high-heme meat significantly increased the fecal level of apparent total N-nitroso compounds (ATNC) and the number of MDF per colon compared with the no-meat control diet (P < 0.05). This nitrite-treated and oxidized cured meat specifically increased the MDF number compared with similar nonnitrite-treated meat (P = 0.03) and with similar nonoxidized meat (P = 0.004). Thus, a model cured meat, similar to ham stored aerobically, increased the number of preneoplastic lesions, which suggests colon carcinogenesis promotion. Nitrite treatment and oxidation increased this promoting effect, which was linked with increased fecal ATNC level. This study could lead to process modifications to make nonpromoting processed meat.

Abstract A25: Public and provider awareness and use of a CA‐125 test for ovarian cancer

Abstract: Introduction: CA‐125 is a serum marker approved for detecting recurrent ovarian cancer in women with a personal history of ovarian cancer. Several large trials have investigated the use of CA‐125 (alone or in combination with transvaginal ultrasound [TVU]) as a screening test for ovarian cancer. However, this test has generally been associated with a low positive predictive value and trials have concluded that screening asymptomatic women in the average risk population with CA‐125 is not beneficial. Still, there remains widespread discussion and marketing of ovarian cancer screening tests that include CA‐125. Since little is known about public and provider awareness of CA‐125, the objective of this study was to measure women9s familiarity with the CA‐125 test, and clinician beliefs about the effectiveness of screening for ovarian cancer with CA‐125 in the United States. Methods: In 2008, CDC funded the collection of data as part of its national awareness campaign, Inside Knowledge: Get the Facts About Gynecologic Cancer. Several questions related to CA‐125 were included as part of a standardized, survey administered annually in the contiguous United States by Porter Novelli. The HealthStyles survey included 2,991 female respondents age ≥ 18 years, and the DocStyles survey included 1,250 physician respondents of family/general practitioners (n=510), internists (n=490), and obstetrician/gynecologists (n=250). Participant responses to CA‐125‐related questions for the HealthStyles survey were weighted to match the demographic distribution of the general population. Chi‐square tests were used to assess differences with the p‐value set to 0.05. Results: Overall, most women (56%) had not heard of the CA‐125 test, 29% had heard of it, and 15% were unsure. Demographic characteristics generally were similar for women who had not heard of the CA‐125 test, except that women who had heard of the test more often were over age 45 (58% vs 37%) (p Conclusions: The large percentage of physicians who believe CA‐125 is an effective screen for ovarian cancer signals the need for improved education. Educational efforts geared toward the public and providers that include both lack of evidence for screening with CA‐125, as well as the potential harms of false‐positive CA‐125 tests should be a priority for public health programs and awareness campaigns. Citation Information: Cancer Prev Res 2010;3(1 Suppl):A25.

A Randomized, Double-Blind, Placebo-Controlled Phase 3 Skin Cancer Prevention Study of α-Difluoromethylornithine in Subjects with Previous History of Skin Cancer

Abstract: Preclinical studies have shown that the inhibition of ornithine decarboxylase (ODC) by α-difluoromethylornithine (DFMO) and resultant decreases in tissue concentrations of polyamines (putrescine and spermidine) prevents neoplastic developments in many tissue types. Clinical studies of oral DFMO at 500 mg/m 2 /day revealed it to be safe and tolerable and resulted in significant inhibition of phorbol ester–induced skin ODC activity. Two hundred and ninety-one participants (mean age, 61 years; 60% male) with a history of prior nonmelanoma skin cancer (NMSC; mean, 4.5 skin cancers) were randomized to oral DFMO (500 mg/m 2 /day) or placebo for 4 to 5 years. There was a trend toward a history of more prior skin cancers in subjects randomized to placebo, but all other characteristics including sunscreen and nonsteroidal anti-inflammatory drug use were evenly distributed. Evaluation of 1,200 person-years of follow-up revealed a new NMSC rate of 0.5 events/person/year. The primary end point, new NMSCs, was not significantly different between subjects taking DFMO and placebo (260 versus 363 cancers, P = 0.069, two-sample t test). Evaluation of basal cell (BCC) and squamous cell cancers separately revealed very little difference in squamous cell cancer between treatment groups but a significant difference in new BCC (DFMO, 163 cancers; placebo, 243 cancers; expressed as event rate of 0.28 BCC/person/year versus 0.40 BCC/person/year, P = 0.03). Compliance with DFMO was >90% and it seemed to be well tolerated with evidence of mild ototoxicity as measured by serial audiometric examination when compared with placebo subjects. The analysis of normal skin biopsies revealed a significant ( P P = 0.069) in new NMSC that was predominantly due to a marked reduction in new BCC. Based on these data, the potential of DFMO, alone or in combination, to prevent skin cancers should be explored further. Cancer Prev Res; 3(1); 35–47

Epigallocatechin Gallate Suppresses Lung Cancer Cell Growth through Ras–GTPase-Activating Protein SH3 Domain-Binding Protein 1

Abstract: Green tea is a highly popular beverage globally. Green tea contains a number of polyphenol compounds referred to as catechins, and (-)-epigallocatechin gallate (EGCG) is believed to be the major biologically active compound found in green tea. EGCG has been reported to suppress lung cancer, but the molecular mechanisms of the inhibitory effects of EGCG are not clear. We found that EGCG interacted with the Ras-GTPase-activating protein SH3 domain-binding protein 1 (G3BP1) with high binding affinity (K(d) = 0.4 micromol/L). We also showed that EGCG suppressed anchorage-independent growth of H1299 and CL13 lung cancer cells, which contain an abundance of the G3BP1 protein. EGCG was much less effective in suppressing anchorage-independent growth of H460 lung cancer cells, which express much lower levels of G3BP1. Knockdown shG3BP1-transfected H1299 cells exhibited substantially decreased proliferation and anchorage-independent growth. shG3BP1 H1299 cells were resistant to the inhibitory effects of EGCG on growth and colony formation compared with shMock-transfected H1299 cells. EGCG interfered with the interaction of G3BP1 and the Ras-GTPase-activating protein and further suppressed the activation of Ras. Additional results revealed that EGCG effectively attenuated G3BP1 downstream signaling, including extracellular signal-regulated kinase and mitogen-activated protein kinase/extracellular signal-regulated kinase kinase, in wild-type H1299 and shMock H1299 cells but had little effect on H460 or shG3BP1 H1299 cells. Overall, these results strongly indicate that EGCG suppresses lung tumorigenesis through its binding with G3BP1.

Nano-Bio-Chip sensor platform for examination of oral exfoliative cytology

Abstract: Oral cancer is a deadly and disfiguring disease that could greatly benefit from new diagnostic approaches enabling early detection. In this pilot study, we describe a nano-bio-chip (NBC) sensor technique for analysis of oral cancer biomarkers in exfoliative cytology specimens, targeting both biochemical and morphologic changes associated with early oral tumorigenesis. Here, oral lesions from 41 dental patients, along with normal epithelium from 11 healthy volunteers, were sampled using a noninvasive brush biopsy technique. Specimens were enriched, immunolabeled, and imaged in the NBC sensor according to previously established assays for the epidermal growth factor receptor (EGFR) biomarker and cytomorphometry. A total of 51 measurement parameters were extracted using custom image analysis macros, including EGFR labeling intensity, cell and nuclear size, and the nuclear-to-cytoplasmic ratio. Four key parameters were significantly elevated in both dysplastic and malignant lesions relative to healthy oral epithelium, including the nuclear area and diameter ( P P P

Synthetic triterpenoids prolong survival in a transgenic mouse model of pancreatic cancer.

Abstract: Pancreatic cancer is the fourth leading cause of cancer-related deaths in the United States and is nearly always fatal Whereas early detection offers the most promising approach for reducing the mortality of this disease, there is still a need to develop effective drugs for the prevention and treatment of pancreatic cancer We tested two promising classes of noncytotoxic drugs, synthetic oleanane triterpenoids and rexinoids, for the prevention of carcinogenesis in the highly relevant LSL-Kras(G12D/+);LSL-Trp53(R127H/+);Pdx-1-Cre (KPC) mouse model of pancreatic cancer KPC transgenic mice closely recapitulate the genetic mutations, clinical symptoms, and histopathology found in human pancreatic cancer Beginning at 4 weeks of age, mice were fed powdered control diet or a diet containing the triterpenoids CDDO-methyl ester (CDDO-Me) or CDDO-ethyl amide, the rexinoid LG100268 (LG268), or the combination, until the mice displayed overt symptoms of pancreatic cancer CDDO-Me, LG268, the combination of CDDO-Me and LG268, and the combination of CDDO-ethyl amide and LG268, all significantly (P < 005) increased survival in the KPC mice by 3 to 4 weeks Recent studies have shown that gemcitabine, the current standard of care for human pancreatic cancer, does not extend survival in KPC mice In cell lines developed from the KPC mice, the triterpenoids directly interact with both signal transducer and activator of transcription 3 and IκB kinase (IKK) to decrease constitutive interleukin-6 secretion, inhibit constitutive signal transducer and activator of transcription 3 phosphorylation, and block the degradation of IκBα when challenged with tumor necrosis factor α These results suggest that oleanane triterpenoids and rexinoids have the potential to prevent pancreatic cancer

A Large Prospective Study of SEP15 Genetic Variation, Interaction with Plasma Selenium Levels, and Prostate Cancer Risk and Survival

Abstract: The role of selenium in prostate cancer (PCa) risk remains controversial, but many epidemiologic studies suggest an inverse association with more aggressive disease. A recently discovered selenoprotein, SEP15, which is highly expressed in the prostate, may play a role either independently or by modifying the effects of selenium. We genotyped four common single-nucleotide polymorphisms capturing common variation (frequency >5%; R 2 > 0.8) within SEP15 , as well as rs5859 in the 3′ untranslated region, previously reported to reduce the efficiency of selenium incorporation into SEP15. We examined the association of these single-nucleotide polymorphisms with PCa risk and PCa-specific mortality, as well as their interactions with plasma selenium levels, in the Physicians' Health Study. In this nested case-control study (1,286 cases and 1,267 controls), SEP15 polymorphisms were not significantly associated with PCa risk. However, among the cases, three variants were significantly associated with PCa-specific mortality [rs479341 hazard ratio (HR), 1.94; 95% confidence interval (95% CI), 1.15-3.25; rs1407131 HR, 2.85; 95% CI, 1.45-5.59; rs561104 HR, 1.54; 95% CI, 1.12-2.11] with a recessive model. Additionally, rs561104 significantly modified the association of plasma selenium with PCa survival ( P interaction = 0.02); an inverse relationship of high levels of selenium with PCa mortality was apparent only among those without the increased risk genotype. This study provides evidence that SEP15 genetic variation may influence PCa mortality. Additionally, the association of selenium with PCa mortality was modified by a variant, suggesting the possibility that some men with PCa may benefit more from selenium than others, depending on their genotype. Cancer Prev Res; 3(5); 604–10. ©2010 AACR. Read the Perspective on this article by Platz, [p. 576][1] [1]: /lookup/volpage/3/576

The Core Circadian Gene Cryptochrome 2 Influences Breast Cancer Risk, Possibly by Mediating Hormone Signaling

Abstract: As transcriptional regulators, circadian genes have the potential to influence a variety of biological pathways, including many cancer-related processes. Cryptochrome 2 (CRY2) is essential for proper circadian timing, and is a key component of the circadian regulatory feedback loop. Here, we report findings from genetic, epigenetic, loss-of-function, and transcriptional profiling analyses of CRY2 in breast cancer. Six SNPs in CRY2 were identified for genotyping in a case-control population (N=441 cases and N=479 controls), and three SNPs (rs11038689, rs7123390, and rs1401417) were significantly associated with postmenopausal breast cancer risk, with significant effect modification by menopausal status (dominant model for rs11038689: odds ratio (OR) = 0.71, 95% confidence interval (CI): 0.51–0.99, P for trend = 0.028; homozygous variants for rs7123390: OR = 0.44, 95% CI: 0.22–0.86, P for trend = 0.028; and rs1401417, OR=0.44, 95% CI: 0.21–0.92, P for trend = 0.017). Interestingly, this association was only evident in women with estrogen and progesterone receptor (ER/PR) negative breast tumors, but not with ER/PR positive tumors. Breast cancer patients also had significantly higher levels of CRY2 promoter methylation relative to controls, which is consistent with tissue array data showing lower levels of CRY2 expression in tumor tissue relative to adjacent normal tissue. Furthermore, in vitro analyses identified a number of breast cancer-relevant genes which displayed altered expression following CRY2 knockdown. These findings suggest a role for CRY2 in breast tumorigenesis, and provide further evidence that the circadian system may be an important modulator of hormone-related cancer susceptibility.

Green Tea Polyphenols and Metabolites in Prostatectomy Tissue: Implications for Cancer Prevention

Abstract: Epidemiologic, preclinical, and clinical trials suggest that green tea consumption may prevent prostate cancer through the action of green tea polyphenols including (-)-epigallocatechin-3-gallate (EGCG). To study the metabolism and bioactivity of green tea polyphenols in human prostate tissue, men with clinically localized prostate cancer consumed six cups of green tea (n = 8) daily or water (n = 9) for 3 to 6 weeks before undergoing radical prostatectomy. Using high-performance liquid chromatography, 4''-O-methyl EGCG (4''-MeEGCG) and EGCG were identified in comparable amounts, and (-)-epicatechin-3-gallate was identified in lower amounts in prostatectomy tissue from men consuming green tea (38.9 +/- 19.5, 42.1 +/- 32.4, and 17.8 +/- 10.1 pmol/g tissue, respectively). The majority of EGCG and other green tea polyphenols were not conjugated. Green tea polyphenols were not detected in prostate tissue or urine from men consuming water preoperatively. In the urine of men consuming green tea, 50% to 60% of both (-)-epigallocatechin and (-)-epicatechin were present in methylated form with 4'-O-MeEGC being the major methylated form of (-)-epigallocatechin. When incubated with EGCG, LNCaP prostate cancer cells were able to methylate EGCG to 4''-MeEGCG. The capacity of 4''-MeEGCG to inhibit proliferation and NF-kappaB activation and induce apoptosis in LNCaP cells was decreased significantly compared with EGCG. In summary, methylated and nonmethylated forms of EGCG are detectable in prostate tissue following a short-term green tea intervention, and the methylation status of EGCG may potentially modulate its preventive effect on prostate cancer, possibly based on genetic polymorphisms of catechol O-methyltransferase.

Cryptotanshinone inhibits cancer cell proliferation by suppressing Mammalian target of rapamycin-mediated cyclin D1 expression and Rb phosphorylation.

Abstract: Cryptotanshinone (CPT), a natural compound isolated from the plant Salvia miltiorrhiza Bunge, is a potential anticancer agent. However, little is known about its anticancer mechanism. Here we show that CPT inhibited cancer cell proliferation by arresting cells in G1/G0 phase of the cell cycle. This is associated with inhibiting expression of cyclin D1 and phosphorylation of retinoblastoma (Rb) protein. Furthermore, we found that CPT inhibited the signaling pathway of the mammalian target of rapamycin (mTOR), a central regulator of cell proliferation. This is evidenced by the findings that CPT inhibited type I insulin-like growth factor (IGF-1) or 10% fetal bovine serum (FBS)-stimulated phosphorylation of mTOR, p70 S6 kinase 1 (S6K1) and eukaryotic initiation factor 4E (eIF4E) binding protein 1 (4E-BP1), in a concentration- and time-dependent manner. Expression of constitutively active mTOR conferred resistance to CPT inhibition of cyclin D1 expression and Rb phosphorylation, as well as cell growth. The results suggest that CPT is a novel anti-proliferative agent.

Deficiency in the 15 kDa Selenoprotein Inhibits Tumorigenicity and Metastasis of Colon Cancer Cells

Abstract: Selenium has cancer-preventive activity that is mediated, in part, through selenoproteins. The role of the 15-kDa selenoprotein (Sep15) in colon cancer was assessed by preparing and using mouse colon CT26 cells stably transfected with short hairpin RNA constructs targeting Sep15. Metabolic 75Se labeling and Northern and Western blot analyses revealed that >90% of Sep15 was downregulated. Growth of the resulting Sep15-deficient CT26 cells was reduced (P 250 lung metastases per mouse; however, mice injected with cells with downregulation of Sep15 only had 7.8 ± 5.4 metastases. To investigate molecular targets affected by Sep15 status, gene expression patterns between control and knockdown CT26 cells were compared. Ingenuity Pathways Analysis was used to analyze the 1,045 genes that were significantly (P

Genome-Wide Catalogue of Chromosomal Aberrations in Barrett's Esophagus and Esophageal Adenocarcinoma: A High-Density Single Nucleotide Polymorphism Array Analysis

Abstract: To better understand the molecular mechanisms behind esophageal adenocarcinoma (EAC) tumorigenesis, we used high-density single nucleotide polymorphism arrays to profile chromosomal aberrations at each of the four sequential progression stages, Barrett's metaplasia (BM), low-grade dysplasia (LGD), high-grade dysplasia (HGD), and EAC, in 101 patients. We observed a significant trend toward increasing loss of chromosomes with higher progression stage. For BM, LGD, HGD, and EAC, respectively, the average numbers of chromosome arms with loss per sample were 0.30, 3.21, 7.70, and 11.90 (P for trend = 4.82 x 10(-7)), and the mean percentages of single nucleotide polymorphisms with allele loss were 0.1%, 1.8%, 6.6%, and 17.2% (P for trend = 2.64 x 10(-6)). In LGD, loss of 3p14.2 (68.4%) and 16q23.1 (47.4%) was limited to narrow regions within the FHIT (3p14.2) and WWOX (16q23.1) genes, whereas loss of 9p21 (68.4%) occurred in larger regions. A significant increase in the loss of other chromosomal regions was seen in HGD and EAC. Loss of 17p (47.6%) was one of the most frequent events in EAC. Many recurrent small regions of chromosomal loss disrupted single genes, including FHIT, WWOX, RUNX1, KIF26B, MGC48628, PDE4D, C20orf133, GMDS, DMD, and PARK2, most of which are common fragile site regions in the human genome. However, RUNX1 at 21q22 seemed to be a potential tumor suppressor gene in EAC. Amplifications were less frequent than losses and mostly occurred in EAC. 8q24 (containing Myc) and 8p23.1 (containing CTSB) were the two most frequently amplified regions. In addition, a significant trend toward increasing amplification was associated with higher progression stage.