Carcinogenic Events Research Articles

Sorafenib Action in Hepatitis B Virus X-Activated Oncogenic Androgen Pathway in Liver through SHP-1.

Hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) shows a higher incidence in men, mainly because of hepatitis B X (HBx)-mediated enhancement of androgen receptor (AR) activity. We aimed to examine this pathway in hepatocarcinogenesis and to identify drug(s) specifically blocking this carcinogenic event in the liver. HBx transgenic mice that spontaneously develop HCC (n = 28-34 per group) were used, either by knockout of hepatic AR or by castration. Efficacy of several HCC-targeted drugs in suppressing HBx-induced AR activity was evaluated, and cellular factors mediating suppression were investigated in cultured cells. Tissue specificity of the candidate drug was validated using mouse tissues. Data were analyzed with Chi-square and Student's t tests. All statistical tests were two-sided. The androgen pathway was shown to be important in early stage hepatocarcinogenesis of HBx transgenic mice. The tumor incidence was decreased from 80% to 32% by AR knockout (P < .001) and from 90% to 25% by early castration (P < .001). Sorafenib markedly inhibited the HBx-enhanced AR activity through activating the SHP-1 phosphatase, which antagonized the activation of Akt/GSK3β and c-Src by HBx. Moreover, SHP-1 protein level was much higher in the liver than in testis, which enabled sorafenib to inhibit aberrant AR activity in the HBx-expressing liver, while not affecting the physiological AR function in normal liver or testis. The androgen pathway may be a druggable target for the chemoprevention of HBV-related HCC, and sorafenib might be used as a tissue- and disease-specific regimen for the chemoprevention of HBV-related HCC.

Interactional role of microRNAs and bHLH-PAS proteins in cancer (Review).

MicroRNAs (miRNAs) are recognized as an emerging class of master regulators that regulate human gene expression at the post-transcriptional level and are involved in many normal and pathological cellular processes. Mammalian basic HLH (helix-loop-helix)-PER-ARNT-SIM (bHLH-PAS) proteins are heterodimeric transcriptional regulators that sense and respond to environmental signals (such as chemical pollutants) or to physiological signals (for instance hypoxia). In the normal state, bHLH-PAS proteins are responsible for multiple critical aspects of physiology to ensure the cell accurate homeostasis, but dysregulation of these proteins has been shown to contribute to carcinogenic events such as tumor initiation, promotion, and progression. Increasing epidemiological and experimental studies have shown that bHLH-PAS proteins regulate a panel of miRNAs, whereas some miRNAs also target bHLH-PAS proteins. The interaction between miRNAs and certain bHLH-PAS proteins [hypoxia-inducible factor (HIF) and aryl hydrocarbon receptor (AHR)] is relevant to many vital events associated with tumorigenesis. This review will summarize recent findings on the interesting and complicated underlying mechanisms that miRNAs interact with HIFs or AHR in tumors, hopefully to benefit the discovery of novel drug-interfering targets for cancer therapy.

Trypanosomiasis-induced megacolon illustrates how myenteric neurons modulate the risk for colon cancer in rats and humans.

BackgroundTrypanosomiasis induces a remarkable myenteric neuronal degeneration leading to megacolon. Very little is known about the risk for colon cancer in chagasic megacolon patients. To clarify whether chagasic megacolon impacts on colon carcinogenesis, we investigated the risk for colon cancer in Trypanosoma cruzi (T. cruzi) infected patients and rats.MethodsColon samples from T. cruzi-infected and uninfected patients and rats were histopathologically investigated with colon cancer biomarkers. An experimental model for chemical myenteric denervation was also performed to verify the myenteric neuronal effects on colon carcinogenesis. All experiments complied the guidelines and approval of ethical institutional review boards.ResultsNo colon tumors were found in chagasic megacolon samples. A significant myenteric neuronal denervation was observed. Epithelial cell proliferation and hyperplasia were found increased in chagasic megacolon. Analyzing the argyrophilic nucleolar organiser regions within the cryptal bottom revealed reduced risk for colon cancer in Chagas’ megacolon patients. T. cruzi-infected rats showed a significant myenteric neuronal denervation and decreased numbers of colon preneoplastic lesions. In chemical myenteric denervated rats preneoplastic lesions were reduced from the 2nd wk onward, which ensued having the colon myenteric denervation significantly induced.Conclusion/SignificanceOur data suggest that the trypanosomiasis-related myenteric neuronal degeneration protects the colon tissue from carcinogenic events. Current findings highlight potential mechanisms in tropical diseases and cancer research.

Interleukin-1 receptor antagonist (IL1RN) is associated with suppression of early carcinogenic events in human oral malignancies.

Inflammatory abnormalities have been implicated in the pathogenesis of various human diseases, including cancer. Interleukin-1 receptor antagonist (IL1RN) is a potent anti-inflammatory molecule that modulates the biological activity of the proinflammatory cytokine, interleukin-1. The aim of this study was to examine the expression of IL1RN in oral squamous cell carcinomas (OSCCs), and to determine its clinical significance. Expression levels of IL1RN in matched normal and tumor specimens from 39 OSCCs were evaluated using real-time quantitative polymerase chain reaction methods, and immunohistochemical analysis. Protein expression of IL1RN was also examined in 18 oral premalignant lesions (OPLs). Expression of IL1RN mRNA was significantly downregulated in OSCCs compared with normal tissues. Decreased expression of IL1RN protein was also observed in OPLs and OSCCs. The IL1RN expression level was lower in the OPL cases with severe dysplasia compared to those with mild/moderate dysplasia. Significantly downregulated IL1RN expression was observed in all OSCC lesion sites examined when compared with the matched normal tissues. However, the decreased level of IL1RN expression did not correspond with tumor progression. Noteworthy, IL1RN expression was higher in the advanced OSCC cases (T3/T4) compared to early cases (T1/T2). Among OSCC samples, relatively higher IL1RN expression was associated with active tumor development in the OSCCs occurring in the buccal mucosa, oral floor, fauces and gingiva, but not the tongue. These data suggest that IL1RN may exhibit opposing characteristics in oral malignancies depending on the stage of cancer development, suppressing early carcinogenic events, yet promoting tumor development in some lesion sites. Thus, IL1RN could represent a reliable biomarker for the early diagnosis of OSCCs. Furthermore, IL1RN may possess unknown and complex functions in the developed OSCC.

Cytological Evaluation of Tongue Cells and Buccal Mucosa Cells

Objective: C-erbB-2 expression has been detected in 40 to 60% of head and neck squamous cell carcinomas (HNSCC). With regard to preneoplastic lesions, thus suggesting that the loss of CerbB-2 expression is a carcinogenic molecular event. Study Design: This study was conducted on a total of 20 paraffin-embedded HNSCC samples, which were histopathologically diagnosed at the Department of Pathology of medicine Hospital between 2010 and 2011. Paraffin-embedded HNSCC samples 3 mm in thickness, were then cut. The slides were stained with C-erbB-2. Results: There was significant relationship between staining density and differentiation grade (R1⁄4 0,922671). Conclusions: Consequently, it was concluded that cerbB-2 is a poor prognostic factor in HNSCC like in breast tumour.

Helicobacter pyloriCagA Suppresses Apoptosis through Activation of AKT in a Nontransformed Epithelial Cell Model of Glandular Acini Formation

H. pylori infection is the most important environmental risk to develop gastric cancer, mainly through its virulence factor CagA. In vitro models of CagA function have demonstrated a phosphoprotein activity targeting multiple cellular signaling pathways, while cagA transgenic mice develop carcinomas of the gastrointestinal tract, supporting oncogenic functions. However, it is still not completely clear how CagA alters cellular processes associated with carcinogenic events. In this study, we evaluated the capacity of H. pylori CagA positive and negative strains to alter nontransformed MCF-10A glandular acini formation. We found that CagA positive strains inhibited lumen formation arguing for an evasion of apoptosis activity of central acini cells. In agreement, CagA positive strains induced a cell survival activity that correlated with phosphorylation of AKT and of proapoptotic proteins BIM and BAD. Anoikis is a specific type of apoptosis characterized by AKT and BIM activation and it is the mechanism responsible for lumen formation of MCF-10A acini in vitro and mammary glands in vivo. Anoikis resistance is also a common mechanism of invading tumor cells. Our data support that CagA positive strains signaling function targets the AKT and BIM signaling pathway and this could contribute to its oncogenic activity through anoikis evasion.

Beneficial bacteria stimulate host immune cells to counteract dietary and genetic predisposition to mammary cancer in mice

Recent studies suggest health benefits including protection from cancer after eating fermented foods such as probiotic yogurt, though the mechanisms are not well understood. Here we tested mechanistic hypotheses using two different animal models: the first model studied development of mammary cancer when eating a Westernized diet, and the second studied animals with a genetic predilection to breast cancer. For the first model, outbred Swiss mice were fed a Westernized chow putting them at increased risk for development of mammary tumors. In this Westernized diet model, mammary carcinogenesis was inhibited by routine exposure to Lactobacillus reuteri ATCC-PTA-6475 in drinking water. The second model was FVB strain erbB2 (HER2) mutant mice, genetically susceptible to mammary tumors mimicking breast cancers in humans, being fed a regular (non-Westernized) chow diet. We found that oral supplement with these purified lactic acid bacteria alone was sufficient to inhibit features of mammary neoplasia in both models. The protective mechanism was determined to be microbially-triggered CD4+CD25+ lymphocytes. When isolated and transplanted into other subjects, these L. reuteri-stimulated lymphocytes were sufficient to convey transplantable anti-cancer protection in the cell recipient animals. These data demonstrate that host immune responses to environmental microbes significantly impact and inhibit cancer progression in distal tissues such as mammary glands, even in genetically susceptible mice. This leads us to conclude that consuming fermentative microbes such as L. reuteri may offer a tractable public health approach to help counteract the accumulated dietary and genetic carcinogenic events integral in the Westernized diet and lifestyle.What's new?Can eating fermented foods like yogurt ward off cancer? Recent studies have suggested it's possible. To find out how, these authors isolated the probiotic bacteria involved in fermentation and fed them to mice that were susceptible to mammary tumors. These mice either had genetic changes predisposing them to cancer or were fed a diet known to increase their likelihood of developing the tumors. Eating the lactic acid bacteria stimulated an immune response that delayed the onset of tumors in both models, suggesting a potential avenue to prevent the cancer in humans.

Altered expression of inflammation-associated genes in oviductal cells following follicular fluid exposure: Implications for ovarian carcinogenesis

Evidence indicates that high-grade serous ovarian carcinoma (HGSOC) may originate from lesions within the distal fallopian tube epithelium (FTE). Our previous studies indicate that fallopian tube epithelial cells from carriers of germline mutations in breast cancer susceptibility genes exhibit a pro-inflammatory gene expression signature during the luteal phase, suggesting that delayed resolution of postovulatory inflammatory signaling may contribute to predisposition to this ovarian cancer histotype. To determine whether exposure of tubal epithelial cells to periovulatory follicular fluid alters expression of inflammation-associated genes, we used an ex vivo culture system of bovine oviductal epithelial cells. Oviductal cells grown on collagen IV-coated transwell membranes assumed a cobblestone appearance and immunocytochemistry for FoxJ1 and Pax8 indicated that both ciliated and secretory epithelial cells were maintained in the cultures. Oviductal cells were exposed to human follicular fluid or culture medium for 24 h following which total cellular RNA was extracted at various time points. Expression of genes associated with inflammation was determined by quantitative real-time RT-PCR. Exposure to follicular fluid transiently increased the transcript levels of interleukin 8 (IL8) and cyclooxygenase 2 (PTGS2), and decreased the expression of mitochondrial superoxide dismutase (SOD2), glutathione peroxidase 3 (GPX3), disabled homolog 2 (DAB2), and glucocorticoid receptor (NR3C1). Tumor necrosis factor (TNF) and IL6 levels were also decreased while those of nicotinomide phosphoribosyltransferase (NAMPT) were unaffected. This study demonstrates that periovulatory follicular fluid can act directly upon oviductal epithelial cells to alter gene expression that might contribute to early carcinogenic events. Furthermore, these findings illustrate the potential use of bovine oviductal cells to study signaling events implicated in ovarian carcinogenesis.

Emodin modulates epigenetic modifications and suppresses bladder carcinoma cell growth

The deregulation of epigenetics was involved in early and subsequent carcinogenic events. Reversing cancer epigenetics to restore a normal epigenetic condition could be a rational approach for cancer treatment and specialized prevention. In the present study, we found that the expression levels of two epigenetic markers, histone H3K27 trimethylation (H3K27me3), was low but histone H3S10 phosphorylation (pH3Ser10) was high in human bladder cancer tissues, which showed opposite expression patterns in their normal counterparts. Thus, we investigated whether a natural product, emodin, has the ability to reverse these two epigenetic modifications and inhibit bladder cancer cell growth. Emodin significantly inhibited the cell growth of four bladder cancer cell lines in a dose- and time-dependent manner. Emodin treatment did not induce specific cell cycle arrest, but it altered epigenetic modifications. Emodin treatment resulted in the suppression of pH3Ser10 and increased H3K27me3, contributing to gene silencing in bladder cancer cells. Microarray analysis demonstrated that oncogenic genes including fatty acid binding protein 4 (FABP4) and fibroblast growth factor binding protein 1 (HBP17), RGS4, tissue inhibitor of metalloproteinase 3 (TIMP3), WNT5b, URB, and collagen, type VIII, alpha 1 (COL8A1) responsible for proliferation, survival, inflammation, and carcinogenesis were significantly repressed by emodin. The ChIP assays also showed that emodin increased H3K27me3 but decreased pH3Ser10 modifications on the promoters of repressed genes, which indicate that emodin reverses the cancer epigenetics towards normal epigenetic situations. In conclusion, our work demonstrates the significant anti-neoplastic activity of emodin on bladder cancer cells and elucidates the novel mechanisms of emodin-mediated epigenetic modulation of target genes. Our study warrants further investigation of emodin as an effective therapeutic or preventive agent for bladder cancer.

Procalcitonin beyond the acute phase: novel biomediator properties?

Since inflammation has been linked to carcinogenic events, discovery of relevant biomarkers may have important preventative implications. Procalcitonin (ProCT) has been shown to be an important prognostic biomarker in severe inflammatory conditions, but there is no data regarding its biomarker role, if any, beyond the acute phase. In a recent study published in BMC Medicine, Cotoi et al. analyzed whether serum ProCT levels in healthy individuals are associated with mortality outcomes. The results are affirmative in that baseline ProCT was shown to be strongly and independently associated with all-cause and cancer mortality and with the incidence of colon cancer in men. By contrast, the study indicated that high sensitivity C-reactive protein was independently associated with cardiovascular mortality but not with cancer mortality in men. Thus, baseline levels of ProCT appear to have prognostic biomarker implications potentially related to its emerging biomediator action(s).

HDAC Up-Regulation in Early Colon Field Carcinogenesis Is Involved in Cell Tumorigenicity through Regulation of Chromatin Structure

Normal cell function is dependent on the proper maintenance of chromatin structure. Regulation of chromatin structure is controlled by histone modifications that directly influence chromatin architecture and genome function. Specifically, the histone deacetylase (HDAC) family of proteins modulate chromatin compaction and are commonly dysregulated in many tumors, including colorectal cancer (CRC). However, the role of HDAC proteins in early colorectal carcinogenesis has not been previously reported. We found HDAC1, HDAC2, HDAC3, HDAC5, and HDAC7 all to be up-regulated in the field of human CRC. Furthermore, we observed that HDAC2 up-regulation is one of the earliest events in CRC carcinogenesis and observed this in human field carcinogenesis, the azoxymethane-treated rat model, and in more aggressive colon cancer cell lines. The universality of HDAC2 up-regulation suggests that HDAC2 up-regulation is a novel and important early event in CRC, which may serve as a biomarker. HDAC inhibitors (HDACIs) interfere with tumorigenic HDAC activity; however, the precise mechanisms involved in this process remain to be elucidated. We confirmed that HDAC inhibition by valproic acid (VPA) targeted the more aggressive cell line. Using nuclease digestion assays and transmission electron microscopy imaging, we observed that VPA treatment induced greater changes in chromatin structure in the more aggressive cell line. Furthermore, we used the novel imaging technique partial wave spectroscopy (PWS) to quantify nanoscale alterations in chromatin. We noted that the PWS results are consistent with the biological assays, indicating a greater effect of VPA treatment in the more aggressive cell type. Together, these results demonstrate the importance of HDAC activity in early carcinogenic events and the unique role of higher-order chromatin structure in determining cell tumorigenicity.

Tipifarnib and farnesyltransferase inhibitors in the treatment of inflammatory breast cancer: is the story over? A review

Inflammatory breast cancer (IBC) is a rare but aggressive form of breast cancer with unique clinicopathological features and poor prognosis. Its epidemiology is distinct from noninflammatory locally advanced breast cancer (LABC), which points to different etiology. With the advent of multimodality treatment for LABC, the outcomes for women with IBC have improved, but remain significantly inferior to outcomes for noninflammatory LABC. This review focuses on new research in epidemiology and molecular pathways characteristic for IBC. One of the critical carcinogenic events apparently driving the development and progression of IBC is activation of the RhoC protein, which is a part of the Ras oncogene superfamily. These proteins, like other Ras proteins, require posttranslational prenylation for their activation and transfer to cell membranes. Farnesylation is a common type of prenlyation that can be blocked with a new class of drugs - farnesyltransferase inhibitors. The most advanced farnesyltransferase inhibitor in development, tipifarnib, has been evaluated in Phase II clinical trials as monotherapy and in combination with antihormonal agents and trastuzumab in metastatic and locally advanced breast cancer. A few tumor responses have been observed in these trials, but not enough to warrant a Phase III trial. Potential combinations of tipifarnib with other novel agents targeting enzymes downstream to RhoC are reviewed. Some of these drugs, such as imatinib and crizotinib, are already commercially available. Others like perifosine and anti-vascular endothelial growth factor 3 antibody are currently under development. Innovative trial designs to address this rare type of cancer are discussed.

Abstract 5557: BoxA and ethyl pyruvate offer novel therapeutic approaches for human malignant mesothelioma.

Abstract Human malignant mesothelioma (MM) is an aggressive and highly lethal cancer that has been linked to asbestos and erionite exposure. MM causes about 3,000 deaths per year in the US and more than 100,000 deaths per year worldwide. We previously found that the damage-associated molecular pattern (DAMP) high-mobility group box-1 protein (HMGB1) plays a critical role in the early carcinogenic events in MM development by inducing tumor necrosis factor-alpha (TNF-α) secretion, potentiating survival of fiber-exposed primary human mesothelial cells (HM) and enabling HM malignant transformation. We recently showed that HMGB1 is upregulated in MM tumor tissues and cell lines and its levels to be significantly higher in the blood of MM patients compared to healthy individuals. Moreover, MM cells are “addicted” to HMGB1 and HMGB1 promotes proliferation, viability, motility and invasiveness of MM cells. Here we show that the use of the HMGB1 antagonists BoxA or ethyl pyruvate (EP) inhibit the motility, survival and progression of MM cells in vitro and reduce the growth of MM xenografts in SCID mice. BoxA is a fragment of HMGB1 protein that corresponds to the one of the two highly conserved DNA binding domains, and behaves as a competitive inhibitor. EP is the ethyl ester of pyruvic acid, is known to suppress oxygen radical formation, and suppresses HMGB1 secretion. Both BoxA and EP have been shown to down-regulate the activation of the proinflammatory transcription factor, NF-κB, as well as the expression of several proinflammatory proteins, such as TNF-α, IL-6, and HMGB1 itself. Taken together, our results provide a preclinical proof-of-principle that inhibition of HMGB1 activity using either BoxA or EP is sufficient to elicit therapeutic activity, offering novel therapeutic approaches for MM treatment. Citation Format: Sandro L. Jube, Zeyana Rivera, Maura Casalgrandi, Marco Bianchi, Harvey I. Pass, Giovanni Gaudino, Michele Carbone, Haining Yang. BoxA and ethyl pyruvate offer novel therapeutic approaches for human malignant mesothelioma. [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 5557. doi:10.1158/1538-7445.AM2013-5557

Insights into the field carcinogenesis of ovarian cancer based on the nanocytology of endocervical and endometrial epithelial cells

Ovarian cancer ranks fifth in cancer fatalities among American women. Although curable at early stages with surgery, most women are diagnosed with symptoms of late-stage metastatic disease. Moreover, none of the current diagnostic techniques are clinically recommended for at-risk women as they preferentially target low-grade tumors (which do not affect longevity) and fail to capture early signatures of more lethal serous tumors which originate in the fimbrae region of the fallopian tubes. Hence, the early detection of ovarian cancer is challenging given the current strategy. Recently, our group has developed a novel optical imaging technique, partial wave spectroscopic (PWS) microscopy, that can quantify the nanoscale macromolecular density fluctuations within biological cells via a biomarker, disorder strength (Ld ). Using the concept of field carcinogenesis, we propose a method of detecting ovarian cancer by PWS assessment of endometrial and endocervical columnar cells. The study includes 26 patients (controls = 15, cancer = 11) for endometrium and 23 (controls = 13, cancer = 10) for endocervix. Our results highlight a significant increase in Ld (% fold-increase > 50%, p-value < 0.05) for columnar epithelial cells obtained from cancer patients compared to controls for both endocervix and endometrium. Overall, the quantification of field carcinogenic events in the endometrium and the novel observation of its extension to the cervix are unique findings in the understanding of ovarian field carcinogenesis. We further show independent validation of the presence of cervical field carcinogenesis with micro-RNA expression data.

BK virus–associated urinary bladder carcinoma in transplant recipients: report of 2 cases, review of the literature, and proposed pathogenetic model

Despite strong experimental evidence, BK polyomavirus involvement in human cancers has been controversial. We report 2 cases of kidney ± pancreas transplant recipients with evidence of BK polyomavirus reactivation, who developed aggressive urinary bladder urothelial carcinomas with adenocarcinomatous and/or micropapillary differentiation. Diffuse strong nuclear positivity for viral T antigen, p53, Ki-67, and p16 was observed in both malignancies. The BK polyomavirus role in promoting urothelial neoplasia in transplant recipients may be partly indirect, based on the demonstration by polymerase chain reaction in both tumors of BK polyomavirus with intact open reading frames and close phylogenetic clustering with known replication-competent strains, and viral capsid protein VP1 messenger RNA and intranuclear virions by electron microscopy in 1 tumor. No unique cancer-associated mutations were found, but some viral T antigen mutations were potentially associated with increased rate of viral replication and risk for "rare" carcinogenic events. The BK polyomavirus-induced profound effects on cell activation, cell cycle shift to proliferation, and apoptosis inhibition, in the context of marked immunosuppression, constitute a potentially ideal background for malignant transformation. The long time lapse between transplantation and tumor manifestation, 7 and 11 years, respectively, further supports the concept of multistep carcinogenesis cascade and long-term risk for these patients. We propose a model of changes ranging from viral reactivation to dysplasia to invasive carcinoma. Clinical vigilance is warranted for early diagnosis of BK polyomavirus-related urothelial malignancies in transplant recipients.

Obesity, metabolism and the microenvironment: Links to cancer

Historically, cancer research has focused on identifying mutations or amplification of genes within the tumor, which informed the development of targeted therapies against affected pathways. This work often considers tumor cells in isolation; however, it is becoming increasingly apparent that the microenvironment surrounding tumor cells strongly influences tumor onset and progression. This is the so-called “seed and soil” hypothesis wherein the seed (cancer cell) is fed and molded by the metabolites, growth factors, modifications of the extracellular matrix or angiogenic factors provided by the soil (or stroma). Currently, 65% of the US population is obese or overweight; similarly staggering figures are reported in US children and globally. Obesity mediates and can exacerbate, both normal and tumor microenvironment dysfunction. Many obesity-associated endocrine, metabolic and inflammatory mediators are suspected to play a role in oncogenesis by modifying systemic nutrient metabolism and the nutrient substrates available locally in the stroma. It is vitally important to understand the biological processes linking obesity and cancer to develop better intervention strategies aimed at curbing the carcinogenic events associated with obesity. In this review, obesity-driven changes in both the normal and tumor microenvironment, alterations in metabolism, and release of signaling molecules such as endocrine, growth, and inflammatory mediators will be highlighted. In addition, we will discuss the effects of the timing of obesity onset or particular “windows of susceptibility,” with a focus on breast cancer etiology.

Abstract P4-13-07: Meta-analysis of epidemiological studies of Insulin Glargine and Breast Cancer Risk

Abstract After having lain dormant for a while, the association between diabetes, its risk factors and treatments, and cancer risk and death is now high on the clinical and research agenda. The microscope is currently focused on the relationships between Pioglitazone and Bladder Cancer, Exenatide and Pancreas Cancer, Liraglutide and pancreas cancer and insulin use and lung cancer. The potential association between use of insulin glargine and breast cancer risk has been the subject of recent major studies. All data regarding cancer risk and use of insulin glargine has been assembled and meta-analyses performed using state-of-the-art statistical methodology. A random effects model was employed with tests for heterogeneity (I2) and publication bias. These meta-analyses are based on reports from 21 epidemiological studies involving over one million patients and 3 million person-years of observation. Based on independent estimates from these studies, the Summary Relative Risk (SRR) for all forms of cancer was (SRR = 0.91, 95% CI (0.84, 0.99)), and for breast cancer SRR = 1.11 (95% CI (1.00, 1.48)). For new users of glargine, the SRR for breast cancer was SRR = 1.22 (95% CI (1.00, 1.48)). For colorectal cancer the SRR = 0.83 (95% CI (0.74, 0.94)) and for prostate cancer SRR = 1.14 (95% CI (0.93, 1.39)). Overall, the risk of developing cancer among users of insulin glargine is reduced compared to the risk of users of other insulins. Similarly, the risk of colorectal cancer is reduced among users of glargine. While the lower bound of the 95% confidence interval is 1.00, the risk of breast cancer does not increase with increasing duration of use of glargine. In some studies the trend in risk with increasing duration of use goes in opposite directions. The development of a detectable breast cancer from the initial carcinogenic event depends on the tumour doubling time. The time for a de novo breast cancer to become detectable ranges from 12.3 years for a doubling time of 150 days; 16.4 years for a doubling time of 200 days; and 20.5 years for a doubling time of 250 days. Most published studies have a maximum of 3–4 years of glargine use. The databases employed in these analyses were not designed for such epidemiological investigation. A major limitation is the absence of knowledge as to why a potential treatment was prescribed for an individual and why a change in therapy was indicated. Further potential limitations to this meta-analysis include that the comparison group was not the same in all studies but this could also be seen as a strength. The meta-analysis of the randomized trials had several insulin comparators and the retinopathy study had NPH as the comparator. This is not likely to invalidate the findings of this analysis nor would the fact that different adjustments were made in the individual studies. The current evidence gives no support to the hypothesis that insulin glargine is associated with an increased risk of cancer as compared to other insulins and should give reassurance to physicians and their patients. In respect to breast cancer, there is no indication of a causal association between use of insulin glargine and increased risk of breast cancer. Citation Information: Cancer Res 2012;72(24 Suppl):Abstract nr P4-13-07.

Local bone marrow renin–angiotensin system in primitive, definitive and neoplastic haematopoiesis

The locally active ligand peptides, mediators, receptors and signalling pathways of the haematopoietic BM (bone marrow) autocrine/paracrine RAS (renin-angiotensin system) affect the essential steps of definitive blood cell production. Haematopoiesis, erythropoiesis, myelopoiesis, formation of monocytic and lymphocytic lineages, thrombopoiesis and other stromal cellular elements are regulated by the local BM RAS. The local BM RAS is present and active even in primitive embryonic haematopoiesis. ACE (angiotensin-converting enzyme) is expressed on the surface of the first endothelial and haematopoietic cells, forming the marrow cavity in the embryo. ACE marks early haematopoietic precursor cells and long-term blood-forming CD34(+) BM cells. The local autocrine tissue BM RAS may also be active in neoplastic haematopoiesis. Critical RAS mediators such as renin, ACE, AngII (angiotensin II) and angiotensinogen have been identified in leukaemic blast cells. The local tissue RAS influences tumour growth and metastases in an autocrine and paracrine fashion via the modulation of numerous carcinogenic events, such as angiogenesis, apoptosis, cellular proliferation, immune responses, cell signalling and extracellular matrix formation. The aim of the present review is to outline the known functions of the local BM RAS within the context of primitive, definitive and neoplastic haematopoiesis. Targeting the actions of local RAS molecules could represent a valuable therapeutic option for the management of neoplastic disorders.

The Attenuation of Early Benzo(a)Pyrene-Induced Carcinogenic Insults by Diallyl Disulfide (DADS) in MCF-10A Cells

Diallyl disulfide (DADS), a garlic organosulfur compound, has been researched as a cancer prevention agent; however, the role of DADS in the suppression of cancer initiation in nonneoplastic cells has not been elucidated. To evaluate DADS inhibition of early carcinogenic events, MCF-10A cells were pretreated (PreTx) with DADS followed by the ubiquitous carcinogen benzo(a)pyrene (BaP), or cotreated (CoTx) with DADS and BaP for up to 24 h. The cells were evaluated for changes in cell viability/proliferation, cell cycle, induction of peroxide formation, and DNA damage. BaP induced a statistically significant increase in cell proliferation at 6 h, which was attenuated with DADS CoTx. PreTx with 6 and 60 μM of DADS inhibited BaP-induced G2/M arrest by 68% and 78%, respectively. DADS, regardless of concentration or method, inhibited BaP-induced extracellular aqueous peroxide formation within 24 h. DADS attenuated BaP-induced DNA single-strand breaks at all time points through both DADS Pre- and CoTx, with significant inhibition for all treatments sustained after 6 h. DADS was effective in inhibiting BaP-induced cell proliferation, cell cycle transitions, reactive oxygen species, and DNA damage in a normal cell line, and thus may inhibit environmentally induced breast cancer initiation.

Protection by silibinin against experimental ischemic stroke: Up-regulated pAkt, pmTOR, HIF-1α and Bcl-2, down-regulated Bax, NF-κB expression

Inflammation and apoptosis play an important role in cerebral ischemic pathogenesis and may represent a target for treatment. Silibinin has been proved to elicit a variety of biological effects through its anti-inflammatory and anti-apoptotic properties in hepatotoxic, cancer and carcinogenic events. Whether this protective effect applies to ischemic injury in brain is still unknown, we therefore investigated the potential protective role of silibinin in ischemic stroke and the underlying mechanisms. Silibinin was administered intragastric 30min before permanent middle cerebral artery occlusion (pMCAO). We found that silibinin significantly alleviated neurological deficit, reduced infarct volume, and suppressed brain edema, which were accompanied with upregulation of pAkt, pmTOR, HIF-1α, Bcl-2 and downregulation of Bax, NF-κB in ischemic brain tissue after stroke. Our results show that silibinin might exert anti-inflammatory and anti-apoptotic effects in ischemic brain through activating Akt/mTOR signaling.