Drugs For Cancer Prevention Research Articles

Early-Phase Development of Cancer Prevention Agents: Challenges and Opportunities

Chemoprevention is the administration of agents (drugs, biologics, dietary supplements, or nutrients) to reduce the risk of developing cancer or prevent the recurrence of cancer. The National Cancer Institute, Division of Cancer Prevention (NCI, DCP), is a major sponsor of cancer preventive preclinical and clinical research. As such, it has developed a comprehensive drug development program specifically designed to meet the requirements needed for cancer preventive drugs to achieve initial regulatory approval. Clinical development of cancer prevention agents presents unique challenges that are not encountered with most cancer therapeutic agents. To meet these challenges, NCI, DCP has implemented new approaches and programs, including phase 0 clinical trial designs and microdose studies. In addition, the PREVENT Cancer Program was recently implemented by NCI, DCP to offer a formalized structure for moving drugs forward in the prevention pipeline using a continue/not continue decision process. Likewise, DCP has implemented a Clinical Trials Consortium to further develop these agents. These and other approaches will be discussed in this commentary.

Abstract 1752: Consequences of high Chromosome Instability (CIN) in SGO1(Shugoshin1) CIN model mice.

Abstract Abstract Mitotic errors have been suspected to be a cause of aneuploidy, rapid accumulation of mutations, and tumorigenesis. In addition, recent cell biological studies demonstrated that mitotic errors can result in DNA damage, which would also aid accumulation of mutations then carcinogenesis. However, no observations in vivo have been provided to support the cell biological observations to date. Previously we developed two strains of high Chromosome Instability (CIN) model mice, which show an increase in mitotic errors due to haploinsufficiency in chromosome cohesion system component Sgo1 or mitotic spindle checkpoint component BubR1. The pathways affected by these mutations are suggested to play a role in aging and carcinogenesis in human. Consistently, compared with wild type, both mice strains showed a significant risk for tumor development in colon with chemical carcinogenesis assays. In this study, we used these CIN mice to test whether (i) spontaneous carcinogenesis occurs in the mice, (ii) spontaneous DNA damage occurs in the mice, (iii) whether associated marker expressions are altered, and (iv) if so, whether it is affected by the age. In 12 month old (middle-age) SGO1 and BUBR1 mice, we observed an increase in spontaneous epithelial cancers, although the carcinogenic effect is not aggressive (p<0.05 in SGO1). In histologically normal-looking liver tissue in the mice, increased signals of DNA damage marker pohspho-gamma-H2AX and p53 were observed (4∼5-fold higher in CIN mice), along with altered expressions of p16INK4A and Bcl2 (2∼6-fold higher in CIN mice), providing the first evidence for DNA damage in vivo with mutations that increase mitotic errors. In 4 month old (younger adult) SGO1 mice, significantly (p<0.05) higher percentage of p-H2AX signal in comparison with wild type was also observed. The results demonstrate that mitotic error and CIN-causing mutation can cause higher DNA damage in the tissue-level, indicating that an additional path to carcinogenesis is at work in vivo. Marker analysis in the CIN model mice would indicate molecular consequences of this type of mutation and would lead to the discovery of novel cancer prevention drug targets. Citation Format: Hiroshi Y. Yamada, Yuting Zhang, Wei Dai, Chinthalapally V. Rao. Consequences of high Chromosome Instability (CIN) in SGO1(Shugoshin1) CIN model mice. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1752. doi:10.1158/1538-7445.AM2013-1752

Saponins extracted from by‐product of Asparagus officinalis L. suppress tumour cell migration and invasion through targeting Rho GTPase signalling pathway

The inedible bottom part (~30-40%) of asparagus (Asparagus officinalis L.) spears is usually discarded as waste. However, since this by-product has been reported to be rich in many bioactive phytochemicals, it might be utilisable as a supplement in foods or natural drugs for its therapeutic effects. In this study it was identifed that saponins from old stems of asparagus (SSA) exerted potential inhibitory activity on tumour growth and metastasis. SSA suppressed cell viability of breast, colon and pancreatic cancers in a concentration-dependent manner, with half-maximum inhibitory concentrations ranging from 809.42 to 1829.96 µg mL(-1). However, SSA was more functional in blocking cell migration and invasion as compared with its cytotoxic effect, with an effective inhibitory concentration of 400 µg mL(-1). A mechanistic study showed that SSA markedly increased the activities of Cdc42 and Rac1 and decreased the activity of RhoA in cancer cells. SSA inhibits tumour cell motility through modulating the Rho GTPase signalling pathway, suggesting a promising use of SSA as a supplement in healthcare foods and natural drugs for cancer prevention and treatment.

Targeted Therapy for Breast Cancer Prevention

With a better understanding of the etiology of breast cancer, molecularly targeted drugs have been developed and are being testing for the treatment and prevention of breast cancer. Targeted drugs that inhibit the estrogen receptor (ER) or estrogen-activated pathways include the selective ER modulators (tamoxifen, raloxifene, and lasofoxifene) and aromatase inhibitors (AIs) (anastrozole, letrozole, and exemestane) have been tested in preclinical and clinical studies. Tamoxifen and raloxifene have been shown to reduce the risk of breast cancer and promising results of AIs in breast cancer trials, suggest that AIs might be even more effective in the prevention of ER-positive breast cancer. However, these agents only prevent ER-positive breast cancer. Therefore, current research is focused on identifying preventive therapies for other forms of breast cancer such as human epidermal growth factor receptor 2 (HER2)-positive and triple-negative breast cancer (TNBC, breast cancer that does express ER, progesterone receptor, or HER2). HER2-positive breast cancers are currently treated with anti-HER2 therapies including trastuzumab and lapatinib, and preclinical and clinical studies are now being conducted to test these drugs for the prevention of HER2-positive breast cancers. Several promising agents currently being tested in cancer prevention trials for the prevention of TNBC include poly(ADP-ribose) polymerase inhibitors, vitamin D, and rexinoids, both of which activate nuclear hormone receptors (the vitamin D and retinoid X receptors). This review discusses currently used breast cancer preventive drugs, and describes the progress of research striving to identify and develop more effective preventive agents for all forms of breast cancer.

Common drugs and treatments for cancer and age-related diseases: revitalizing answers to NCI's provocative questions

In 2011, The National Cancer Institute (NCI) has announced 24 provocative questions on cancer. Some of these questions have been already answered in "NCI's provocative questions on cancer: some answers to ignite discussion" (published in Oncotarget, 2011, 2: 1352.) The questions included "Why do many cancer cells die when suddenly deprived of a protein encoded by an oncogene?" "Can we extend patient survival by using approaches that keep tumors static?" "Why are some disseminated cancers cured by chemotherapy alone?" "Can we develop methods to rapidly test interventions for cancer treatment or prevention?" "Can we use our knowledge of aging to enhance prevention or treatment of cancer?" "What is the mechanism by which some drugs commonly and chronically used for other indications protect against cancer?" "How does obesity contribute to cancer risk?" I devoted a single subchapter to each the answer. As expected, the provocative questions were very diverse and numerous. Now I choose and combine, as a single problem, only three last questions, all related to common mechanisms and treatment of age-related diseases including obesity and cancer. Can we use common existing drugs for cancer prevention and treatment? Can we use some targeted "cancer-selective" agents for other diseases and … aging itself.

Abstract A58: High Throughput Search for a Combination Cancer Preventive Treatment

Abstract Identification of safer chemopreventive drugs is essential for the future of cancer preventive treatment. Although the feasibility for chemoprevention of estrogen receptor (ER) -positive breast cancers has been exemplified by the use of selective estrogen response modifiers (SERMs), we are still lacking preventive options for many other disease types, including breast cancers not dependent on ER status. Rexinoids are a class of agents that effectively reduce the incidence of both ER-positive and -negative tumors in animal models of breast cancer and thus may be better cancer preventive drugs than the current standard SERMs. However, significant side-effects at the effective clinical dose, including hypertriglyceridemia and weight gain, limit its generalized use. A phase II biomarker trial of the synthetic rexinoid, bexarotene (Targretin, LGD1069) demonstrated that bexarotene reduces expression of the proliferation markers Ki67 and Cyclin D1 in normal breast epithelium of postmenopausal women, suggesting that the cancer preventive effects of bexarotene are associated with its ability to elicit cell cycle blockade and inhibit proliferation of premalignant mammary epithelial cells. Here we hypothesize that the combination of repurposed drugs and some small molecule compounds with low dose rexinoid will minimize toxicity and result in effective anti-proliferative in premalignant cells. Therefore, we designed an image-based in vitro assay system to conduct high throughput screens to identify existing drugs and drug-like small molecules which enhance the growth suppressive effect of cancer preventive rexinoids. We used an automated 96 well platform to test the NIH clinical collection of drugs and a library of structurally diverse compounds (MayBridge Hitfinder) alone or in combination with 100nM bexarotene. Through multiparametric determination of cell counts, DNA content and cellular toxicity, we identified combination treatments of premalignant breast cells that fit the above criteria and report on dose-response studies and secondary screens for optimal dose and cell health. Validation of some of the candidate agents and plans for in vivo testing of their chemopreventive activity will be discussed. Citation Format: Ivan P. Uray, Powel H. Brown. High-throughput search for a combination cancer preventive treatment. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr A58.

Abstract B23: Sulfotransferase isoform 1A1 (SULT1A1) gene expression is regulated by transcription factor NF1 in human breast cancer cell lines.

Abstract Sulfotransferase isoform 1A1 (SULT1A1), a cytosolic phase II detoxification enzyme, plays a central role in drug metabolism, and breast cancer treatment and prevention drugs such as tamoxifen (TAM) and raloxifene (RAL) are among its substrates. Thus, regulation of this gene in target tissues could influence the efficacy of therapy. SULT1A1 activity varies several-fold in human populations, and genetic variants within the gene only account for a small proportion of the observed variability. Expression also varies with tissue type, with SULT1A1 being more highly expressed in breast tumors than in normal breast tissue. We have identified human nuclear factor 1(NF1) as a potential transcription factor (TF) regulating SULT1A1 gene expression in the ZR-75 breast cancer cell line. The NF1 gene family consists of NF1A, NF1B, NF1C, and NF1X. In order to determine the potential transcriptional regulation of SULT1A1 by NF1 genes in breast cancer in vitro, we measured and compared the mRNA levels of SULT1A1, NF1A, NF1B, NF1C, and NF1X in different human breast cancer cell lines (MCF7, T47D, ZR-75, and MDA-231) and the transformed human epithelial cell line MCF10A. SULT1A1 gene expression in each cell line was highly positively correlated with the gene expression of NF1B (p<0.01), NF1C (p<0.01), and NF1X (p<0.05). To determine if NF1s had a direct effect on SULT1A1 gene expression, ZR-75 cells, which have highest SULT1A1 gene expression among the cell lines tested, were transfected with siRNAs directed against NF1A, NF1B, NF1C, or NF1X for 48 hr. Real-time RT-PCR showed that mRNA levels of NF1A, NF1B, NF1C, and NF1X were decreased 70% ± 0.02, 87% ± 0.08, 81% ± 0.08, and 86% ± 0.12, respectively after transfection. SULT1A1 gene expression decreased 41% ± 0.05 (p=0.05) in siNF1A transfected cells and 64% ± 0.08 (p=0.05) in siNF1C transfected cells. ZR-75 cells were also co-transfected with siNF1A, siNF1B, and siNF1C for 48 hr. SULT1A1 mRNA level was decreased approximately 40%, indicating that there was no additive transcription regulatory effect on SULT1A1 gene expression among those three NF1s. Interestingly, SULT1A1 gene expression was decreased more than four-fold in siNF1B transfected MCF7 cells. In summary, our data demonstrates that SULT1A1 activity is partially regulated at the transcription level by transcription factors NF1A, NF1B, and NF1C. We are currently examining the expression levels of these genes in both normal and breast tumor tissue to identify a mechanistic explanation for the differential expression of SULT1A1 between normal breast tissue and breast tumors. This knowledge will lead to better predictors of therapeutic efficacy for chemopreventive agents that are substrates of SULT1A1. Citation Format: Aiwei Yao-Borengassar, Lora Rogers, Vinay Raj, Susan Kadlubar. Sulfotransferase isoform 1A1 (SULT1A1) gene expression is regulated by transcription factor NF1 in human breast cancer cell lines. [abstract]. In: Proceedings of the Eleventh Annual AACR International Conference on Frontiers in Cancer Prevention Research; 2012 Oct 16-19; Anaheim, CA. Philadelphia (PA): AACR; Cancer Prev Res 2012;5(11 Suppl):Abstract nr B23.

The Combination of Tamoxifen and the Rexinoid LG100268 Prevents ER-Positive and ER-Negative Mammary Tumors in p53-Null Mammary Gland Mice

In pursuit of effective therapeutic agents for the estrogen receptor (ER)-negative breast cancer, we previously showed that bexarotene reduced mammary tumor development by 75% in ErbB2 mice. To further improve the effectiveness of breast cancer prevention, we have now investigated the effects of a combinatorial therapy consisting of two cancer preventive drugs. On the basis of the hypothesis, rexinoid LG100268 plus tamoxifen would more effectively prevent the development of both ER-positive and ER-negative breast cancer. We treated p53-null mammary gland mice with tamoxifen and LG100268, individually and in combination. By 60 weeks of age, vehicle-treated mice developed tumors in 52% of transplanted mammary glands, whereas mice treated with tamoxifen and LG100268 developed tumors in only 13% of transplanted mammary glands. To further define the mechanistic effects of this combinatorial treatment, we investigated the effects of tamoxifen and LG100268 on mammary tissue biomarkers. In mammary tissue harvested before tumor development, the proliferation markers Ki67 and cyclin D1 were significantly reduced in mice treated with the combination therapy. In addition, the rexinoid target genes ABCA1 and ABCG1 were induced in both the rexinoid and combination treatment groups, whereas expression remained constant in tamoxifen group. These results show that tamoxifen-LG100268 combinatorial treatment is more effective in preventing mammary tumors than either agent alone. In addition, these studies have identified relevant tissue biomarkers that can be used to show the effect of these agents on mammary tissue. These results support the development of clinical trials of antiestrogen and rexinoid combinatorial therapy for the prevention of patients with high-risk breast cancer.

Celecoxib induces proliferation and Amphiregulin production in colon subepithelial myofibroblasts, activating erk1–2 signaling in synergy with EGFR

The COX-2 inhibitor Celecoxib, tested in phase III trials for the prevention of sporadic colon adenomas, reduced the appearance of new adenomas, but was unable to affect the incidence of colon cancer. Moreover the 5years follow-up showed that patients discontinuing Celecoxib treatment had an increased incidence of adenomas as compared to the placebo arm. In the APC(min/+) mouse model short term treatment with Celecoxib reduced gut adenomas, but a prolonged administration of the drug induced fibroblast activation and intestinal fibrosis with a final tumor burden. The way Celecoxib could directly activate human colon myofibroblasts (MF) has not yet been investigated.We found that MF are activated by non toxic doses of Celecoxib. Celecoxib induces erk1–2 and Akt phosphorylation within 5′. This short term activation is apparently insufficient to cause phenotypic changes, but the contemporary triggering of EGFR causes an impressive synergic effect inducing MF proliferation and the neo-expression and release of Amphiregulin (AREG), a well known EGFR agonist involved in colon cancer progression. As a confirm to these observations, the erk inhibitor U0126 and the EGFR inhibitors Tyrphostin and Cetuximab were able to contrast AREG induction.Our data provide evidence that Celecoxib directly activates MF empowering EGFR signaling. According to these results the association with EGFR (or erk1–2) inhibitors could abolish the off-target activity of Celecoxib, possibly extending the potential of this drug for colon cancer prevention.

A case for combined ovarian and breast cancer prevention

Targeted prevention of ovarian cancer is hindered by the inaccessibility of ovarian tissue, lack of accepted biomarkers and low disease incidence. However, ovarian cancer has common risk factors and shared etiologies with breast cancer. Chemoprevention of ovarian cancer has been demonstrated incidentally during testing of novel breast cancer prevention drugs. Here it is hypothesized that the development of combined ovarian and breast cancer prevention strategies is a preferable strategy for ovarian cancer prevention.

Green tea: An effective synergist with anticancer drugs for tertiary cancer prevention

Green tea is now an acknowledged cancer preventive in Japan. Based on evidence that colorectal adenomas and prostate cancer in humans have been prevented, we review here the concept that the combination of anticancer drugs with green tea catechin synergistically induces apoptosis of human cancer cells, inhibits tumor formation in mice, and enhances inhibition of tumor growth in xenograft mouse models. As a molecular mechanism by the combination, the induction of growth arrest and DNA damage-inducible 153 (GADD153, CHOP) gene expression is discussed in relation to death receptor 5 and TRAIL-apoptotic pathway. The combination of anticancer drugs with green tea could be a new cancer therapeutic strategy in humans.

Breast Cancer Prevention Drug Reduces BMD

Breast Cancer Prevention Drug Reduces BMD

The Chemopreventive Efficacy of Vandetanib, a Multikinase Inhibitor, in a Primary Respiratory Tract Epithelial Cell Transformation Model

Targeted therapies by means of compounds that inhibit multiple target molecules represent a new perspective in the treatment and prevention of cancer. Vandetanib (Zactima ™ ) is an orally active, selective inhibitor of VEGFR-2 (vascular endothelial growth factor receptor-2) receptor tyrosine kinase that also demonstrates activity against EGFR (epidermal growth factor receptor) and RET (rearranged during transfection) tyrosine kinases. As there are indications of Vandetanib being effective in advanced NSLC patients for disease free survival, we have tested Vandetanib for efficacy in a primary rat tracheal epithelial (RTE) cell transformation model, which was originally developed for identifying potential chemopreventive agents belonging to different chemical classes/biological activity. RTE cells were treated with a tobacco-specific carcinogen, benzo[ a ]pyrene (B[ a ]P) alone or with five nontoxic concentrations of Vandetanib and the resulting transformed foci at the end of 30 days were scored for inhibition of transformation. In order to understand the mechanism(s) of this inhibition, the effect on biomarkers at different stages of RTE cell transformation was also tested. The results indicated that Vandetanib at half-log concentrations ranging from 0.003 – 0.3 μM, elicited an excellent dose-related inhibition of transformation (75- 93%) compared to B[ a ]P group (p = <0.0001). A significant dose-dependent inhibition (39- 93%) of phosphorylated tyrosine kinase activity was observed in Vandetanib-treated groups compared to B[ a ]P group. There was also an approximately 2-fold induction of apoptosis at 0.3 μM, and it inhibited survivin, a late stage biomarker, at all concentrations by 18-28%. In conclusion, the data shows that there is a very good correlation between the inhibition of B[ a ]P-induced transformation and corresponding inhibition of activated tyrosine kinase and other biomarkers. Based on this data, animal studies are planned to develop this drug for lung cancer prevention by administering it directly to the lungs as it was found to be very effective at lower doses compared to therapeutic doses.

Anti-inflammatory Drugs for Cancer Prevention and Treatment: Emerging Options

Anti-inflammatory Drugs for Cancer Prevention and Treatment: Emerging Options

Antiproliferative activity of lignans against the breast carcinoma cell lines MCF 7 and BT 20

Phytoestrogens are plant-derived, non-steroidal phytochemicals with anticarcinogenic potential. The major structural classes are the isoflavones and lignans. The aim of this study was to compare the effect of the plant-derived lignans secoisolariciresinol and matairesinol with the human lignans enterodiol and enterolactone as well as with 17β estradiol and tamoxifen on cell proliferation of breast carcinoma cell lines. The influence of the lignans, 17β estradiol and tamoxifen on cell proliferation was determined using the BrdU test in MCF 7 and BT 20 cell lines. Enterodiol and enterolactone induced a stronger inhibition of cell growth in MCF 7 and BT 20 cells than secoisolariciresinol and matairesinol. The inhibition effects were less expressed in the BT 20 than in the MCF 7 cells. The human lignans enterodiol and enterolactone are more biologically active than their precursors secoisolariciresinol and matairesinol, and may be defined as the real drugs in cancer prevention.

Abstract B69: Cellular neutral lipid content is a novel biomarker of cancer preventive activity

Abstract Introduction: Commonly used biomarkers to assess the cancer preventive activity of cancer preventive agents include markers of cell proliferation or apoptosis. However, the expression of proliferation or apoptosis markers is highly variable, and measurement is often done using semi-quantitative assays. In addition, cancer preventive agents may act through mechanisms that do not depend on proliferation or apoptosis. Therefore, identification of new biomarkers indicative of the cancer preventive activity of chemopreventive agents is essential for the development of new cancer preventive drugs. Methods: We applied high-content microscopic analysis to assess the phenotypic changes occurring in normal mammary epithelial cells (HMECs) after treatment with cancer preventive drugs by measuring cell proliferation, DNA and neutral lipid content and localization, as well as cell cycle distribution of the cells. Gene specific knock-down was achieved by transfections with siRNA duplexes. Measurement of transcript levels was performed using quantitative real-time RT-PCR. Results: Multiparametric analysis of high-throughput image based studies have revealed that anti-proliferative activity of cancer preventive rexinoids is associated with increased formation of cytoplasmic lipid droplets. Accumulation of cytoplasmic neutral lipids was restricted to cell types that undergo significant growth suppression by bexarotene (HMECs, SUM225, and ZR75.1), but not observed in retinoid-resistant cells (MCF10A, HCC1937, and HCC1143). Other growth suppressive drugs including the kinase inhibitor lapatinib, vitamin D, and certain natural compounds, including epicatechine monogallate, duartin, actinonin and homoisoflavonoids, were also found to increase cellular neutral lipid content in breast cells. The addition of external fatty acids, such as oleic and palmitoleic acids did not result in dose-dependent growth suppression or accumulation of neutral esterified lipid droplets. Lipid accumulation and growth suppression were associated with the up-regulation of genes involved in regulating the formation of neutral lipids, triglycerides and phospholipids, but not genes involved in de novo fatty acid synthesis. Conversely, knock-down of key proteins controlling cellular triglyceride synthesis and storage, diacylglycerol acyltransferase 1 (DGAT1) and adipophyllin (Adfp) increased cell proliferation whereas their induction was associated with growth suppression in HMECs. Conclusion: These results suggest that increased accumulation of cellular triglycerides may be a useful biomarker to assess the preventive effect of putative cancer preventive agents. These results support the systematic testing of cellular neutral lipid levels in preclinical and clinical models testing novel chemopreventive agents. This work was supported by the grant RO1 CA 78480 (to P.H.B.). Citation Information: Cancer Prev Res 2011;4(10 Suppl):B69.

Abstract B76: Synthetic triterpenoids as candidate drugs for cancer prevention and treatment

Abstract Angiogenesis is a limiting step for the switch from a dormant to malignant state in tumor progression. During tumor development tumor cells induce profound changes in the surrounding tissue, leading to the formation of an altered tumor microenvironment that is critical in permitting further tumor growth and tumor progression. Retinoblastoma (Rb) and colorectal cancer (CRC) display the complexity of the microenvironment constituted by different cell types and their extracellular matrix. Here we assessed the efficacy of two synthetic derivates of triterpenoid CDDO, CDDO-Im and CDDO-Me, on endothelial, retinoblastoma and colon cancer cells in order to evaluate their effect on angiogenesis, cancer progression and metastatic dissemination. We observed that CDDO-Im and CDDO-Me inhibited endothelial cells proliferation, migration and tube-formation, hampering the nuclear translocation of NF-kB and affecting the MAPK pathway. In vivo, in a matrigel sponge assay CDDO-Im interfered with angiogenesis when administrated into the pellets or by intraperitoneal injection. To assess whether these compounds could successfully impairs neuroectodermal-derived tumor growth, we performed in vitro experiments on Y79 and Weri-Rb1 retinoblastoma cells. We performed MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide] and LDH (Lactate Dehydrogenase) assays to evaluate CDDO-Im effect on retinoblastoma cell viability and an Annexin V and 7-Amino-Actinomycin D staining to test apoptosis. We observed that CDDO-Im treatment induced a reduction of cell viability at nanomolar doses and early and late apoptosis at different time points. In order to overcome the side effects of standard chemotherapy drugs, such as vincristine sulphate, we evaluated if CDDO-Im could be used to lower chemotherapy doses. When we combined non-cytotoxic doses of CDDO-Im with vincristine sulphate we observed that after 72 hours of co-treatment, CDDO-Im was able to accomplish the same antiproliferative effect obtained using double doses of vincristine alone. We also tested the in vitro anti-tumour activity of CDDO-Me on human adenocarcinoma HT29 cell line. The triterpenoid was used alone or in combination with 5FU (5 Fluorouracil), the major chemotherapeutic agent used for CRC therapy. We performed an MTT assay to evaluate its effect on cell viability, an apoptosis test and an alkaline comet assay to assess the potential genotoxic damage. Preliminary results demonstrated that CDDO-Me induced an almost immediate inhibitory effect on HT29 cells, reducing cell viability already after 24 hours of treatment at 1000-fold lower concentration then 5FU. When HT29 were co-treated with both CDDO-Me and 5FU, no additive effects were observed. Respect to 5FU, CDDO-Me did not induce apoptosis even after long-term treatment, as well as genotoxicity, suggesting that it is able to block cell growth without exerting toxic effects. These data suggest that the two synthetic triterpenoid CDDO-Im and CDDO-Me could be promising compounds for cancer treatment, acting both on cancer cells and on endothelial cells that support tumor-associated angiogenesis. Our results open the possibility to use chemopreventive molecules in combination with current chemotherapic drugs, to improve their efficacy without cytotoxicity. Citation Information: Cancer Prev Res 2011;4(10 Suppl):B76.

Menstrual Cycle–related Fluctuations in Breast Density Measured by Using Three-dimensional MR Imaging

To investigate the fluctuation of fibroglandular tissue volume (FV) and percentage of breast density (PD) during the menstrual cycle and compare with postmenopausal women by using three-dimensional magnetic resonance (MR)-based segmentation methods. This study was approved by the Institutional Review Board and was HIPAA compliant. Written informed consent was obtained. Thirty healthy female subjects, 24 premenopausal and six postmenopausal, were recruited. All subjects underwent MR imaging examination each week for 4 consecutive weeks. The breast volume (BV), FV, and PD were measured by two operators to evaluate interoperator variation. The fluctuation of each parameter measured over the course of the four examinations was evaluated on the basis of the coefficient of variation (CV). The results from two operators showed a high Pearson correlation for BV (R(2) = 0.99), FV (R(2) = 0.98), and PD (R(2) = 0.96). The interoperator variation was 3% for BV and around 5%-6% for FV and PD. In the respective premenopausal and postmenopausal groups, the mean CV was 5.0% and 5.6% for BV, 7.6% and 4.2% for FV, and 7.1% and 6.0% for PD. The difference between premenopausal and postmenopausal groups was not significant (all P values > .05). The fluctuation of breast density measured at MR imaging during a menstrual cycle was around 7%. The results may help the design and interpretation of future studies by using the change of breast density as a surrogate marker to evaluate the efficacy of hormone-modifying drugs for cancer treatment or cancer prevention.

Targeting the HER/EGFR/ErbB Family to Prevent Breast Cancer

Preventing breast cancer is possible with selective estrogen receptor (ER) modulators and aromatase inhibitors, which reduce the risk of invasive disease by up to 65% (up to 73% for ER-positive and no effect for ER-negative cancer) and the risk of preinvasive disease [ductal carcinoma in situ (DCIS)] by up to 50%. Clearly, approaches for preventing ER-negative, and increased prevention of ER-positive breast cancers would benefit public health. A growing body of work (including recent preclinical and clinical data) support targeting the HER family [epidermal growth factor receptor (EGFR), or human epidermal growth factor receptor (HER) 1 or ErbB1) and HER2, HER3, and HER4] for preventing ER-negative and possibly ER-positive breast cancer. Preclinical studies of HER family-targeting drugs in mammary neoplasia show suppression of (i) ER-negative tumors in HER2-overexpressing mouse strains, (ii) ER-negative tumors in mutant Brca1/p53(+/-) mice, and (iii) ER-positive tumors in the methylnitrosourea (MNU) rat model; tumors arising in both the MNU and mutant Brca1/p53(+/-) models lack HER2 overexpression. Clinical trials include a recent placebo-controlled phase IIb presurgical trial of the dual EGFR HER2 inhibitor lapatinib that suppressed growth of breast premalignancy [including atypical ductal hyperplasia (ADH) and DCIS] and invasive cancer in patients with early-stage, HER2-overexpressing or -amplified breast cancer. These results suggest that lapatinib can clinically suppress the progression of ADH and DCIS to invasive breast cancer, an effect previously observed in a mouse model of HER2-overexpressing, ER-negative mammary cancer. The preclinical and clinical signals provide a compelling rationale for testing HER-targeting drugs for breast cancer prevention in women at moderate-to-high risk, leading perhaps to combinations that prevent ER-negative and ER-positive breast cancer.

Update on the Chemopreventive Effects of Ginger and its Phytochemicals

The rhizomes of Zingiber officinale Roscoe (Zingiberaceae), commonly known as ginger, is one of the most widely used spice and condiment. It is also an integral part of many traditional medicines and has been extensively used in Chinese, Ayurvedic, Tibb-Unani, Srilankan, Arabic, and African traditional medicines, since antiquity, for many unrelated human ailments including common colds, fever, sore throats, vomiting, motion sickness, gastrointestinal complications, indigestion, constipation, arthritis, rheumatism, sprains, muscular aches, pains, cramps, hypertension, dementia, fever, infectious diseases, and helminthiasis. The putative active compounds are nonvolatile pungent principles, namely gingerols, shogaols, paradols, and zingerone. These compounds are some of the extensively studied phytochemicals and account for the antioxidant, anti-inflammatory, antiemetic, and gastroprotective activities. A number of preclinical investigations with a wide variety of assay systems and carcinogens have shown that ginger and its compounds possess chemopreventive and antineoplastic effects. A number of mechanisms have been observed to be involved in the chemopreventive effects of ginger. The cancer preventive activities of ginger are supposed to be mainly due to free radical scavenging, antioxidant pathways, alteration of gene expressions, and induction of apoptosis, all of which contribute towards decrease in tumor initiation, promotion, and progression. This review provides concise information from preclinical studies with both cell culture models and relevant animal studies by focusing on the mechanisms responsible for the chemopreventive action. The conclusion describes directions for future research to establish its activity and utility as a human cancer preventive and therapeutic drug. The above-mentioned mechanisms of ginger seem to be promising for cancer prevention; however, further clinical studies are warranted to assess the efficacy and safety of ginger.