Gene Signature Associated with Nervous System in an Experimental Radiation- and Estrogen-Induced Breast Cancer Model

Breast cancer is frequently the most diagnosed female cancer in the world. The experimental studies on cancer seldom focus on the relationship between the central nervous system and cancer. Despite extensive research into the treatment of breast cancer, chemotherapy resistance is an important issue limiting the efficacy of treatment. Novel biomarkers to predict prognosis or sensitivity to chemotherapy are urgently needed. This study examined nervous-system-related genes. The profiling of differentially expressed genes indicated that high-LET radiation, such as that emitted by radon progeny, in the presence of estrogen, induced a cascade of events indicative of tumorigenicity in human breast epithelial cells. Bioinformatic tools allowed us to analyze the genes involved in breast cancer and associated with the nervous system. The results indicated that the gene expression of the Ephrin A1 gene (EFNA1), the roundabout guidance receptor 1 (ROBO1), and the kallikrein-related peptidase 6 (KLK6) was greater in T2 and A5 than in the A3 cell line; the LIM domain kinase 2 gene (LIMK2) was greater in T2 than A3 and A5; the kallikrein-related peptidase 7 (KLK7), the neuroligin 4 X-linked gene (NLGN4X), and myelin basic protein (MBP) were greater than A3 only in T2; and the neural precursor cell expressed, developmentally down-regulated 9 gene (NEDD9) was greater in A5 than in the A3 and E cell lines. Concerning the correlation, it was found a positive correlation between ESR1 and EFNA1 in BRCA-LumA patients; with ROBO1 in BRCA-Basal patients, but this correlation was negative with the kallikrein-related peptidase 6 (KLK6) in BRCA-LumA and -LumB, as well as with LIMK2 and ROBO1 in all BRCA. It was also positive with neuroligin 4 X-linked (NLGN4X) in BRCA-Her2 and BRCA-LumB, and with MBP in BRCA-LumA and -LumB, but negative with KLK7 in all BRCA and BRCA-LumA and NEDD9 in BRCA-Her2. The differential gene expression levels between the tumor and adjacent tissue indicated that the ROBO1, KLK6, LIMK2, KLK7, NLGN4X, MBP, and NEDD9 gene expression levels were higher in normal tissues than in tumors; however, EFNA1 was higher in the tumor than the normal ones. EFNA1, LIMK2, ROBO1, KLK6, KLK7, and MBP gene expression had a negative ER status, whereas NEDD9 and NLGN4X were not significant concerning ER status. In conclusion, important markers have been analyzed concerning genes related to the nervous system, opening up a new avenue of studies in breast cancer therapy.

Acetylcholine, Another Factor in Breast Cancer

Acetylcholine (ACh) is a neurotransmitter that regulates multiple functions in the nervous system, and emerging evidence indicates that it could play a role in cancer progression. However, this function is controversial. Previously, we showed that organophosphorus pesticides decreased the levels of the enzyme acetylcholinesterase in vivo, increasing ACh serum levels and the formation of tumors in the mammary glands of rats. Furthermore, we showed that ACh exposure in breast cancer cell lines induced overexpression of estrogen receptor alpha (ERα), a key protein described as the master regulator in breast cancer. Therefore, here, we hypothesize that ACh alters the ERα activity through a ligand-independent mechanism. The results here reveal that the physiological concentration of ACh leads to the release of Ca+2 and the activity of MAPK/ERK and PI3K/Akt pathways. These changes are associated with an induction of p-ERα and its recruitment to the nucleus. However, ACh fails to induce overexpression of estrogen-responsive genes, suggesting a different activation mechanism than that of 17ß-estradiol. Finally, ACh promotes the viability of breast cancer cell lines in an ERα-dependent manner and induces the overexpression of some EMT markers. In summary, our results show that ACh promotes breast cancer cell proliferation and ERα activity, possibly in a ligand-independent manner, suggesting its putative role in breast cancer progression.

Association of Germline Variation in Driver Genes with Breast Cancer Risk in Chilean Population

Cancer is a genomic disease, with driver mutations contributing to tumorigenesis. These potentially heritable variants influence risk and underlie familial breast cancer (BC). This study evaluated associations between BC risk and 13 SNPs in driver genes MAP3K1, SF3B1, SMAD4, ARID2, ATR, KMT2C, MAP3K13, NCOR1, and TBX3, in BRCA1/2-negative Chilean families. SNPs were genotyped using TaqMan Assay in 492 cases and 1285 controls. There were no associations between rs75704921:C>T (ARID2); rs2229032:A>C (ATR); rs3735156:C>G (KMT2C); rs2276738:G>C, rs2293906:C>T, rs4075943T:>A, rs13091808:C>T (MAP3K13); rs178831:G>A (NCOR1); or rs3759173:C>A (TBX3) and risk. The MAP3K1 rs832583 A allele (C/A+A/A) showed a protective effect in families with moderate BC history (OR = 0.7 [95% CI 0.5-0.9] p = 0.01). SF3B1 rs16865677-T (G/T+T/T) increased risk in sporadic early-onset BC (OR = 1.4 [95% CI 1.0-2.0] p = 0.01). SMAD4 rs3819122-C (A/C+C/C) increased risk in cases with moderate family history (OR = 2.0 [95% CI 1.3-2.9] p ≤ 0.0001) and sporadic cases diagnosed ≤50 years (OR = 1.6 [95% CI 1.1-2.2] p = 0.006). SMAD4 rs12456284:A>G increased BC risk in G-allele carriers (A/G + G/G) in cases with ≥2 BC/OC cases and early-onset cases (OR = 1.2 [95% CI 1.0-1.6] p = 0.04 and OR = 1.4 [95% CI 1.0-1.9] p = 0.03, respectively). Our study suggests that specific germline variants in driver genes MAP3K1, SF3B1, and SMAD4 contribute to BC risk in Chilean population.

The Role of MicroRNAs in Breast Cancer and the Challenges of Their Clinical Application

MicroRNAs (miRNAs) constitute a subclass of non-coding RNAs that exert substantial influence on gene-expression regulation. Their tightly controlled expression plays a pivotal role in various cellular processes, while their dysregulation has been implicated in numerous pathological conditions, including cancer. Among cancers affecting women, breast cancer (BC) is the most prevalent malignant tumor. Extensive investigations have demonstrated distinct expression patterns of miRNAs in normal and malignant breast cells. Consequently, these findings have prompted research efforts towards leveraging miRNAs as diagnostic tools and the development of therapeutic strategies. The aim of this review is to describe the role of miRNAs in BC. We discuss the identification of oncogenic, tumor suppressor and metastatic miRNAs among BC cells, and their impact on tumor progression. We describe the potential of miRNAs as diagnostic and prognostic biomarkers for BC, as well as their role as promising therapeutic targets. Finally, we evaluate the current use of artificial intelligence tools for miRNA analysis and the challenges faced by these new biomedical approaches in its clinical application. The insights presented in this review underscore the promising prospects of utilizing miRNAs as innovative diagnostic, prognostic, and therapeutic tools for the management of BC.

Occurrence and exposure assessment of glyphosate in the environment and its impact on human beings

Glyphosate is a broad-spectrum and one of the most widely used herbicides in the world, which has led to its high environmental dissemination. In 2015, the International Agency for Research on Cancer stated that glyphosate was a probable human carcinogen. Since then, several studies have provided new data about the environmental exposure of glyphosate and its consequences on human health. Thus, the carcinogenic effects of glyphosate are still under debate. This work aimed to review glyphosate occurrence and exposure since 2015 up to date, considering studies associated with either environmental or occupational exposure and the epidemiological assessment of cancer risk in humans. These articles showed that herbicide residues were detectable in all spheres of the earth and studies on the population showed an increase in the concentration of glyphosate in biofluids, both in the general population and in the occupationally exposed population. However, the epidemiological studies under review provided limited evidence for the carcinogenicity of glyphosate, which was consistent with the International Agency for Research on Cancer classification as a probable carcinogen.

PI3K/AKT/mTOR Signaling Pathway in HPV-Driven Head and Neck Carcinogenesis: Therapeutic Implications

High-risk human papillomaviruses (HR-HPVs) are the causal agents of cervical, anogenital and a subset of head and neck carcinomas (HNCs). Indeed, oropharyngeal cancers are a type of HNC highly associated with HR-HPV infections and constitute a specific clinical entity. The oncogenic mechanism of HR-HPV involves E6/E7 oncoprotein overexpression for promoting cell immortalization and transformation, through the downregulation of p53 and pRB tumor suppressor proteins, among other cellular targets. Additionally, E6/E7 proteins are involved in promoting PI3K/AKT/mTOR signaling pathway alterations. In this review, we address the relationship between HR-HPV and PI3K/AKT/mTOR signaling pathway activation in HNC with an emphasis on its therapeutic importance.

Glyphosate mimics 17β-estradiol effects promoting estrogen receptor alpha activity in breast cancer cells

Glyphosate, the active ingredient in several broad-spectrum herbicide formulations, has been validated and widely used throughout the world. Recent reports have questioned its safety, showing that glyphosate may act as an endocrine disruptor by promoting estrogenic activity. However, the molecular mechanism involved in this phenomenon remains unclear. Therefore, here we aimed to elucidate the mechanism by which glyphosate induces estrogenic activity using estrogen-sensitive breast cancer cell line models. Our results show that glyphosate mimics the cell effects of 17β-estradiol (E2), promoting estrogen receptor α (ERα) phosphorylation, its degradation, and transcriptional activity at high concentrations. The molecular mechanism seems involved in the ERα ligand-binding domain (LBD). Molecular simulations suggest a plausible interaction between glyphosate and the LBD through a coordinated complex involving divalent cations such as Zn (II). In addition, glyphosate exposure alters the level of Cyclin-dependent kinase 7 that contribute to ERα phosphorylation. Finally, glyphosate increases cell proliferation rate and levels of cell cycle regulators, accompanied by an increase in anchorage-independent growth capacity. These findings suggest that glyphosate at high concentrations, induces estrogen-like effects through an ERα ligand binding site-dependent mechanism, leading to cellular responses resulting from a complex interplay of genomic and non-genomic events.

Breast carcinogenesis induced by organophosphorous pesticides

Breast cancer is a major health threat to women worldwide and the leading cause of cancer-related death. The use of organophosphorous pesticides has increased in agricultural environments and urban settings, and there is evidence that estrogen may increase breast cancer risk in women. The mammary gland is an excellent model for examining its susceptibility to different carcinogenic agents due to its high cell proliferation capabilities associated with the topography of the mammary parenchyma and specific stages of gland development. Several experimental cellular models are presented here, in which the animals were exposed to chemical compounds such as pesticides, and endogenous substances such as estrogens that exert a significant effect on normal breast cell processes at different levels. Such models were developed by the effect of malathion, parathion, and eserine, influenced by estrogen demonstrating features of cancer initiation in vivo as tumor formation in rodents; and in vitro in the immortalized normal breast cell line MCF-10F, that when transformed showed signs of carcinogenesis such as increased cell proliferation, anchorage independence, invasive capabilities, modulation of receptors and genomic instability. The role of acetylcholine was also demonstrated in the MCF-10F, suggesting a role not only as a neurotransmitter but also with other functions, such as induction of cell proliferation, playing an important role in cancer. Of note, this is a unique experimental approach that identifies mechanistic signs that link organophosphorous pesticides with breast carcinogenesis.

Cell Adhesion Molecules Affected by Ionizing Radiation and Estrogen in an Experimental Breast Cancer Model

Cancer develops in a multi-step process where environmental carcinogenic exposure is a primary etiological component, and where cell–cell communication governs the biological activities of tissues. Identifying the molecular genes that regulate this process is essential to targeting metastatic breast cancer. Ionizing radiation can modify and damage DNA, RNA, and cell membrane components such as lipids and proteins by direct ionization. Comparing differential gene expression can help to determine the effect of radiation and estrogens on cell adhesion. An in vitro experimental breast cancer model was developed by exposure of the immortalized human breast epithelial cell line MCF-10F to low doses of high linear energy transfer α particle radiation and subsequent growth in the presence of 17β-estradiol. The MCF-10F cell line was analyzed in different stages of transformation that showed gradual phenotypic changes including altered morphology, increase in cell proliferation relative to the control, anchorage-independent growth, and invasive capability before becoming tumorigenic in nude mice. This model was used to determine genes associated with cell adhesion and communication such as E-cadherin, the desmocollin 3, the gap junction protein alpha 1, the Integrin alpha 6, the Integrin beta 6, the Keratin 14, Keratin 16, Keratin 17, Keratin 6B, and the laminin beta 3. Results indicated that most genes had greater expression in the tumorigenic cell line Tumor2 derived from the athymic animal than the Alpha3, a non-tumorigenic cell line exposed only to radiation, indicating that altered expression levels of adhesion molecules depended on estrogen. There is a significant need for experimental model systems that facilitate the study of cell plasticity to assess the importance of estrogens in modulating the biology of cancer cells.

Health Effects of Pesticide Exposure in Latin American and the Caribbean Populations: A Scoping Review

BACKGROUND

Multiple epidemiological studies have shown that exposure to pesticides is associated with adverse health outcomes. However, the literature on pesticide-related health effects in the Latin American and the Caribbean (LAC) region, an area of intensive agricultural and residential pesticide use, is sparse. We conducted a scoping review to describe the current state of research on the health effects of pesticide exposure in LAC populations with the goal of identifying knowledge gaps and research capacity building needs.

METHODS

We searched PubMed and SciELO for epidemiological studies on pesticide exposure and human health in LAC populations published between January 2007 and December 2021. We identified 233 publications from 16 countries that met our inclusion criteria and grouped them by health outcome (genotoxicity, neurobehavioral outcomes, placental outcomes and teratogenicity, cancer, thyroid function, reproductive outcomes, birth outcomes and child growth, and others).

RESULTS

Most published studies were conducted in Brazil (37%, n = 88 ) and Mexico (20%, n = 46 ), were cross-sectional in design (72%, n = 167 ), and focused on farmworkers (45%, n = 105 ) or children (21%, n = 48 ). The most frequently studied health effects included genotoxicity (24%, n = 62 ) and neurobehavioral outcomes (21%, n = 54 ), and organophosphate (OP) pesticides were the most frequently examined (26%, n = 81 ). Forty-seven percent (n = 112 ) of the studies relied only on indirect pesticide exposure assessment methods. Exposure to OP pesticides, carbamates, or to multiple pesticide classes was consistently associated with markers of genotoxicity and adverse neurobehavioral outcomes, particularly among children and farmworkers.

DISCUSSION

Our scoping review provides some evidence that exposure to pesticides may adversely impact the health of LAC populations, but methodological limitations and inconsistencies undermine the strength of the conclusions. It is critical to increase capacity building, integrate research initiatives, and conduct more rigorous epidemiological studies in the region to address these limitations, better inform public health surveillance systems, and maximize the impact of research on public policies. https://doi.org/10.1289/EHP9934.

Epstein–Barr Virus Association with Breast Cancer: Evidence and Perspectives

Simple Summary

Epstein–Barr virus (EBV) is a very ubiquitous and persistent virus present in ~90% of the world population. The infection is generally asymptomatic during the lifetime, though it can cause lymphoid tumors and carcinomas in some subjects. The role of EBV in breast cancer (BC) has yet to be determined. In this review, we present the historical background and scientific evidence regarding the presence and potential role of EBV in this malignancy and we propose possible molecular mechanisms. Knowledge of EBV´s role in BC will contribute to establishing prevention strategies, early detection, and control of this highly aggressive and prevalent malignancy.

Abstract

Epstein–Barr virus (EBV) is an enveloped DNA virus that belongs to the gamma Herpesviridae family. The virus establishes a latent/lytic persistent infection, though it can be involved in cancer development in some subjects. Indeed, evidence supports an etiological role of EBV in undifferentiated nasopharyngeal carcinoma (NPC), a subset of gastric carcinomas and lymphomas. Additionally, EBV has been detected in breast carcinomas (BCs) although its role has not been established. In this review, we summarize epidemiological information regarding the presence of EBV in BC and we propose mechanistic models. However, additional epidemiological and experimental evidence is warranted to confirm these models.

Muscarinic Receptors Associated with Cancer

Simple Summary

Recently, cancer research has described the presence of the cholinergic machinery, specifically muscarinic receptors, in a wide variety of cancers due to their activation and signaling pathways associated with tumor progression and metastasis, providing a wide overview of their contribution to different cancer formation and development for new antitumor targets. This review focused on determining the molecular signatures associated with muscarinic receptors in breast and other cancers and the need for pharmacological, molecular, biochemical, technological, and clinical approaches to improve new therapeutic targets.

Abstract

Cancer has been considered the pathology of the century and factors such as the environment may play an important etiological role. The ability of muscarinic agonists to stimulate growth and muscarinic receptor antagonists to inhibit tumor growth has been demonstrated for breast, melanoma, lung, gastric, colon, pancreatic, ovarian, prostate, and brain cancer. This work aimed to study the correlation between epidermal growth factor receptors and cholinergic muscarinic receptors, the survival differences adjusted by the stage clinical factor, and the association between gene expression and immune infiltration level in breast, lung, stomach, colon, liver, prostate, and glioblastoma human cancers. Thus, targeting cholinergic muscarinic receptors appears to be an attractive therapeutic alternative due to the complex signaling pathways involved.

Interplay between Epstein-Barr virus infection and environmental xenobiotic exposure in cancer

Epstein-Barr virus (EBV) is a herpesvirus associated with lymphoid and epithelial malignancies. Both B cells and epithelial cells are susceptible and permissive to EBV infection. However, considering that 90% of the human population is persistently EBV-infected, with a minority of them developing cancer, additional factors are necessary for tumor development. Xenobiotics such as tobacco smoke (TS) components, pollutants, pesticides, and food chemicals have been suggested as cofactors involved in EBV-associated cancers. In this review, the suggested mechanisms by which xenobiotics cooperate with EBV for carcinogenesis are discussed. Additionally, a model is proposed in which xenobiotics, which promote oxidative stress (OS) and DNA damage, regulate EBV replication, promoting either the maintenance of viral genomes or lytic activation, ultimately leading to cancer. Interactions between EBV and xenobiotics represent an opportunity to identify mechanisms by which this virus is involved in carcinogenesis and may, in turn, suggest both prevention and control strategies for EBV-associated cancers.

Glyphosate and the key characteristics of an endocrine disruptor: A review

Glyphosate is a large-spectrum herbicide that was introduced on the market in 1974. Due to its important impact on the crop industry, it has been significantly diversified and expanded being considered the most successful herbicide in history. Currently, its massive use has led to a wide environmental diffusion and its human consumption through food products has made possible to detect it in urine, serum, and breast milk samples. Nevertheless, recent studies have questioned its safety and international agencies have conflicting opinions about its effects on human health, mainly as an endocrine-disrupting chemical (EDC) and its carcinogenic capacity. Here, we conduct a comprehensive review where we describe the most important findings of the glyphosate effects in the endocrine system and asses the mechanistic evidence to classify it as an EDC. We use as guideline the ten key characteristics (KCs) of EDC proposed in the expert consensus statement published in 2020 (La Merrill et al., 2020) and discuss the scopes of some epidemiological studies for the evaluation of glyphosate as possible EDC. We conclude that glyphosate satisfies at least 8 KCs of an EDC, however, prospective cohort studies are still needed to elucidate the real effects in the human endocrine system.

Breast and prostate glands affected by environmental substances (Review)

Environmental endocrine disruptor chemicals are substances that can alter the homeostasis of the endocrine system in living organisms. They can be released from several products used in daily activities. Once in the organism, they can disrupt the endocrine function by mimicking or blocking naturally occurring hormones due to their similar chemical structure. This endocrine disruption is the most important cause of the well‑known hormone‑associate types of cancer. Additionally, it is decisive to determine the susceptibility of each organ to these compounds. Therefore, the present review aimed to summarize the effect of different environmental substances such as bisphenol A, dichlorodiphenyltrichloroethane and polychlorinated biphenyls in both the mammary and the prostate tissues. These organs were chosen due to their association with the hormonal system and their common features in carcinogenic mechanisms. Outcomes derived from the present review may provide evidence that should be considered in future debates regarding the effects of endocrine disruptors on carcinogenesis.

Role of organophosphorous pesticides and acetylcholine in breast carcinogenesis

Breast cancer is the leading cause of cancer-related death in women worldwide. Several studies have addressed the association between cancer in humans and agricultural pesticide exposure. Evidence indicates that exposure to organophosphorous pesticides such as parathion and malathion occurs as a result of occupational factors since they are extensively used to control insects. On the other hand, estrogens have been considered beneficial to the organism; however, epidemiological studies have pointed out an increased breast cancer risk in both humans and animals. Experimental female rat mammary gland cancer models were developed after exposure to parathion, malathion, eserine, an acetylcholinesterase inhibitor, and estrogen allowing the analysis of the signs of carcinogenicity as alteration of cell proliferation, receptor expression, genomic instability, and cell metabolism in vivo and in vitro. Thus, pesticides increased proliferative ducts followed by ductal carcinoma; and 17β-estradiol increased proliferative lobules followed by lobular carcinomas. The combination of both pesticides and either eserine or estrogen induced tumors with both types of structures followed by mammary gland tumors and metastasis to the lung and kidneys after 240 days of a 5-day treatment. Studies also showed that these pesticides and eserine decreased three to five times the acetylcholinesterase activity in the serum compared to controls whereas terminal end buds increased in number, being inhibited by atropine. Genomic instability was analyzed in such tissues (mp53, CYP1A2, c-myc, c-fos, ERα, M2R) and pesticides increased protein expression that was stimulated by estrogens but inhibited by atropine. Eserine also transformed the epithelium of the rat mammary gland in the presence of estrogen and increased the number of terminal end buds after treatment inducing mammary carcinomas. Then, enzymatic digestion of such structures gave rise to cells with increased DNA synthesis and induced anchorage independence. Thus, there were changes in the epithelium of the mammary gland influencing breast carcinogenesis. Furthermore, these substances and acetylcholine also showed the signs of carcinogenicity in vitro as cell proliferation, receptor expression (ERα, ErbB2, M2R), genomic instability (c-myc, mp53, ERα, M2R), and cell metabolism. A unique cellular model is also presented here based on the use of MCF-10 F, a non-tumorigenic cell line that represents a valuable clinically translatable experimental approach that identifies mechanistic links for pesticides and estrogen as suspect human carcinogenic agents.

Signs of carcinogenicity induced by parathion, malathion, and estrogen in human breast epithelial cells (Review)

Cancer development is a multistep process that may be induced by a variety of compounds. Environmental substances, such as pesticides, have been associated with different human diseases. Organophosphorus pesticides (OPs) are among the most commonly used insecticides. Despite the fact that organophosphorus has been associated with an increased risk of cancer, particularly hormone-mediated cancer, few prospective studies have examined the use of individual insecticides. Reported results have demonstrated that OPs and estrogen induce a cascade of events indicative of the transformation of human breast epithelial cells. In vitro studies analyzing an immortalized non-tumorigenic human breast epithelial cell line may provide us with an approach to analyzing cell transformation under the effects of OPs in the presence of estrogen. The results suggested hormone-mediated effects of these insecticides on the risk of cancer among women. It can be concluded that, through experimental models, the initiation of cancer can be studied by analyzing the steps that transform normal breast cells to malignant ones through certain substances, such as pesticides and estrogen. Such substances cause genomic instability, and therefore tumor formation in the animal, and signs of carcinogenesis in vitro. Cancer initiation has been associated with an increase in genomic instability, indicated by the inactivation of tumor-suppressor genes and activation of oncogenes in the presence of malathion, parathion, and estrogen. In the present study, a comprehensive summary of the impact of OPs in human and rat breast cancer, specifically their effects on the cell cycle, signaling pathways linked to epidermal growth factor, drug metabolism, and genomic instability in an MCF-10F estrogen receptor-negative breast cell line is provided.

Markers of epithelial-mesenchymal transition in an experimental breast cancer model induced by organophosphorous pesticides and estrogen

Breast cancer is a major health problem and accounted for 11.6% of all new cancer cases and 6.6% of all cancer deaths among women worldwide in 2018. However, its etiology has remained elusive. According to epidemiological studies, environmental factors are influencing the increase in the incidence of breast cancer risk. Components such as chemicals, including pesticides, are agents that produce deleterious effects on wildlife and humans. Among them, the organophosphorus pesticides, such as malathion, have largely been considered in this etiology. The epithelial-mesenchymal transition serves a key role in tumor progression and it is proposed that malathion is closely associated with the origin of this transition, among other causes. Moreover, proteins participating in this process are primordial in the transformation of a normal cell to a malignant tumor cell. The aim of the current study was to evaluate markers that indicated oncogenic properties. The results indicated greater expression levels of proteins associated with the epithelial-to-mesenchymal transition, including E-cadherin, Vimentin, Axl, and Slug in the rat mammary glands treated with malathion alone and combined with estrogen. Atropine was demonstrated to counteract the malathion effect as a muscarinic antagonist. The understanding of the use of markers in experimental models is crucial to identify different stages in the cancer process. The alteration of these markers may serve as a predicting factor that can be used to indicate whether a person has altered ducts or lobules in breast tissue within biopsies of individuals exposed to OPs or other environmental substances.

Human Papillomavirus 16 E7 Promotes EGFR/PI3K/AKT1/NRF2 Signaling Pathway Contributing to PIR/NF-κB Activation in Oral Cancer Cells

A subset of oral carcinomas is etiologically related to high-risk human papillomavirus (HR-HPV) infection, with HPV16 being the most frequent HR-HPV type found in these carcinomas. The oncogenic role of HR-HPV is strongly dependent on the overexpression of E6 and E7 oncoproteins, which, in turn, induce p53 and pRb degradation, respectively. Additionally, it has been suggested that HR-HPV oncoproteins are involved in the regulation of nuclear factor kappa-light-chain-enhancer of activated B cells (NF-κB), inducing cancer progression and metastasis. Previously, we reported that HPV16 E7 oncoprotein promotes Pirin upregulation resulting in increased epithelial–mesenchymal transition (EMT) and cell migration, with Pirin being an oxidative stress sensor and activator of NF-κB. In this study, we demonstrate the mechanism by which HPV16 E7-mediated Pirin overexpression occurs by promoting EGFR/PI3K/AKT1/NRF2 signaling, thus causing PIR/NF-κB activation in oral tumor cells. Our results demonstrate a new mechanism by which E7 contributes to oral cancer progression, proposing PIR as a potential new therapeutic target.

Endocrine disruptors from the environment affecting breast cancer

Evaluation of carcinogenic substances from the environment is a challenge for scientists. Recently, a novel approach based on 10 key characteristics of human carcinogens classified by the International Agency for Research on Cancer (IARC) has emerged. Carcinogenesis depends on different mechanisms and factors, including genetic, infectious (bacteria, viruses) and environmental (chemicals) factors. Endocrine disruptors are exogenous chemicals that can interfere and impair the function of the endocrine system due to their interaction with estrogen receptors or their estrogen signaling pathways inducing adverse effects in the normal mammary development, originating cancer. They are heterogeneous chemicals and include numerous synthetic substances used worldwide in agriculture, industry and consumer products. The most common are plasticizers, such as bisphenol A (BPA), pesticides, such as dichlorodiphenyltrichloroethane, and polychlorinated biphenyls (PCBs). Xenoestrogens appear to serve an important role in the increased incidence of breast cancer in the United States and numerous other countries. Several studies have demonstrated the role of organochlorine xenoestrogens in breast cancer. Therefore, the overall cumulative exposure of women to estrogens results in an increased risk for this type of cancer. Factors like lifestyle and diet also serve a role in the increased incidence of this disease. The aim of the present study was to analyze these chemical compounds based on the key characteristics given by the IARC, with a special focus on breast cancer, to establish whether these compounds are carcinogens, and to create a model for future analysis of other endocrine disruptors.

Merkel cell polyomavirus detected in head and neck carcinomas from Chile

Background

The role of human polyomaviruses (HPyVs) in epithelial tumors such as head and neck carcinomas (HNSCCs) including oral and oropharyngeal carcinomas has not been established. In this study, we evaluated for the first time the presence of Merkel cell polyomavirus (MCPyV), BK human polyomavirus (BKPyV), and JC human polyomavirus (JCPyV) in HNSCCs from Chilean subjects.

Methods

One hundred and twenty HNSCCs were analyzed for the presence of MCPyV, BKPyV and JCPyV using real-time polymerase chain reaction procedures. In addition, 54 oral brushes from age- and sex-paired subjects were analyzed.

Results

Of the total of 120 HNSCCs, 15 were positive for MCPyV (12.5%). Only one case was positive for BKPyV (0.8%) and none for JCPyV (0%). In subjects without cancer, only one case (1.8%) resulted positive for MCPyV and none for JCPyV and BKPyV. MCPyV was associated with HNSCCs (p = 0.0239; OR = 7.571; 95% CI: 1.192–81.46). No association was found between age (p = 0.1996), gender (p = 0.7111) or differentiation status (p > 0.9999) and MCPyV presence in HNSCCs.

Conclusions

MCPyVs were detected in HNSCCs from Chilean patients and were not detected in oral brushes from patients without cancer. More studies are warranted for defining an etiological role and clinical/molecular consequences of these viruses in HNSCCs.

Curcumin rescues breast cells from epithelial‑mesenchymal transition and invasion induced by anti‑miR‑34a

Breast cancer is the most prevalent type of cancer among women worldwide and it is characterized by a high morbidity. Curcumin is a naturally occurring compound derived from the rhizome of Curcuma longa and is known to have antioxidant and anticarcinogenic properties. Emerging evidence has indicated that microRNAs (miRNAs or miRs) function as oncogenes or tumor suppressor genes to control invasion and migration. The aim of this study was to evaluate the effects of curcumin on genes implicated in epithelial-mesenchymal transition (EMT) and to examine the involvement of Rho-A in the migration and invasion of MCF-10F and MDA-MB-231 breast cell lines. Furthermore, to the best of our knowledge, this is the first study to examine the effects of curcumin on Rho-A and on genes involved in EMT, such as Axl, Slug and CD24 in order to determine whether the compound is able to prevent migration and invasion by targeting miRNAs as a regulator of such genes. Specifically, we focused on miR-34a which acts as a tumor suppressor gene in human breast cell lines. The present study demonstrated that the Axl, Slug and CD24 genes were implicated in EMT, and Rho-A was also involved in the migration and invasion of MCF-10F and MDA-MB-231 cell lines. Curcumin also acted upon the miRNA as a regulator of genes implicated in EMT and upon Rho-A as well, affecting the migration and invasion of the cells. This occurred independently of their estrogen receptor (ER), progesterone receptor (PgR) and human epidermal growth factor receptor 2 (HER2) receptors in the non-malignant MCF-10F and malignant MDA-MB-231 breast cell lines, which are both negative for such receptors.

Frequency of hematologic malignancies in the population of Arica, Chile

Hematologic diseases are a heterogeneous group of malignancies that affect people worldwide such as leukemia, lymphoma and multiple myelomas. The aim of this study was to characterize the frequency of hematological diseases in the population of Arica, Chile (18°S, 70°W), between 2011 and 2014. A total of 108 cases of hematologic malignancies were registered at Dr. Juan Noé Crevani Regional Hospital in this period; 40 male and 52 female cases were included in this retrospective and descriptive analysis. The overall median age at diagnosis for hematological malignancies was 59 years (range, 17 to 96 years). The results indicated that the frequency of hematological diseases such as non-Hodgkin lymphoma and leukemia was not associated with sex, ethnicity and type of disease. However, in 2012 there was an increased number of cases of Hodgkin lymphoma compared with any other year in the study, whereas the number of multiple myeloma cases decreased between 2011 and 2014. No significant differences were observed among different types of disease, nor among the types of leukemia. However, when intervals of age were considered, it was revealed that patients >75 years had the highest incidence of hematological malignancies, mainly multiple myeloma, compared with other age groups. However, young adults were more commonly diagnosed with Hodgkin lymphoma than other disease types. A non-significant difference was observed in leukemia between 2011 and 2014 when sex was taken into consideration, in which the incidence rate was higher in females compared with males. Hodgkin lymphoma was most commonly at stage II and non-Hodgkin lymphoma was most commonly at stage IV. No significant differences were observed between the nodal and extranodal type, mixed cellularity and nodular sclerosis or in the morphology of non-Hodgkin lymphoma cell type. Overall, there was a decrease in the frequency of hematological malignancies between 2011 and 2014, but no significant differences were observed in males or females. This study provided for the first time the pattern and distribution of hematological diseases in Arica, Chile.

Curcumin decreases epithelial‑mesenchymal transition by a Pirin‑dependent mechanism in cervical cancer cells

Curcumin is a natural antioxidant polyphenol, which decreases epithelial‑mesenchymal transition (EMT) and cell migration in cervical cancer cells. However, the mechanism by which such a decrease occurs is unclear. It is well established that cervical cancer can be caused by high‑risk human papillomavirus (HPV), which overexpresses E6 and E7 oncoproteins. Recent findings have suggested that viral oncoproteins regulate the expression of Pirin, which is an oxidative stress sensor involved in EMT and cell migration. Molecular markers associated with EMT, pirin and HPV were evaluated using reverse transcription‑reverse quantitative PCR and western blotting. In addition, the migratory ability of cells was evaluated using a Transwell assay. In order to evaluate the role of Pirin in curcumin‑mediated inhibition of EMT, SiHa cervical carcinoma cells, which contain two integrated copies of HPV16, were exposed to curcumin. Cell migration, and the expression levels of EMT biomarkers and the pirin protein, which is a product of the PIR gene, were subsequently evaluated. The results demonstrated a significant decrease in EMT following exposure to 20 µM curcumin for 72 h. This finding was supported by a decrease in the protein expression levels of N‑cadherin, Vimentin and Slug. Furthermore, it was observed that PIR expression and Pirin protein levels were significantly decreased when SiHa cells were exposed to curcumin. Subsequently, to analyze the effects of Pirin on EMT, SiHa cells were transfected with a small interfering RNA (siRNA) to knockdown PIR. A significant increase in E‑cadherin mRNA expression and a decrease in N‑cadherin protein expression were observed. In addition, a similar decrease was observed when SiHa cells were exposed to both PIR siRNA and curcumin. Finally, a significant decrease in SiHa cell migration was observed in the presence of 20 µM curcumin compared with in the control group. These findings suggested that curcumin may decrease EMT, at least in part by a Pirin‑dependent mechanism. Therefore, Pirin protein may be an important pharmacological target for cervical cancer treatment.

Tobacco Exposure Enhances Human Papillomavirus 16 Oncogene Expression via EGFR/PI3K/Akt/c-Jun Signaling Pathway in Cervical Cancer Cells

High-risk human papillomavirus (HR-HPV) infection is not a sufficient condition for cervical cancer development because most infections are benign and naturally cleared. Epidemiological studies revealed that tobacco smoking is a cofactor with HR-HPV for cervical cancer initiation and progression, even though the mechanism by which tobacco smoke cooperates with HR-HPV in this malignancy is poorly understood. As HR-HPV E6/E7 oncoproteins overexpressed in cervical carcinomas colocalize with cigarette smoke components (CSC), in this study we addressed the signaling pathways involved in a potential interaction between both carcinogenic agents. Cervical cancer-derived cell lines, CaSki (HPV16; 500 copies per cell) and SiHa (HPV16; 2 copies per cell), were acutely exposed to CSC at various non-toxic concentrations and we found that E6 and E7 levels were significantly increased in a dose-dependent manner. Using a reporter construct containing the luciferase gene under the control of the full HPV16 long control region (LCR), we also found that p97 promoter activity is dependent on CSC. Non-synonymous mutations in the LCR-resident TPA (12-O-tetradecanoylphorbol 13-acetate)-response elements (TRE) had significantly decreased p97 promoter activation. Phosphoproteomic arrays and specific inhibitors revealed that CSC-mediated E6/E7 overexpression is at least in part reliant on EGFR phosphorylation. In addition, we showed that the PI3K/Akt pathway is crucial for CSC-induced E6/E7 overexpression. Finally, we demonstrated that HPV16 E6/E7 overexpression is mediated by JUN. overexpression, c-Jun phosphorylation and recruitment of this transcription factor to TRE sites in the HPV16 LCR. We conclude that acute exposure to tobacco smoke activates the transcription of HPV16 E6 and E7 oncogenes through p97 promoter activation, which involves the EGFR/PI3K/Akt/C-Jun signaling pathway activation in cervical cancer cells.

Upregulation of PIR gene expression induced by human papillomavirus E6 and E7 in epithelial oral and cervical cells

The hallmark of high-risk human papillomavirus (HR-HPV)-related carcinogenesis is E6 and E7 oncogene overexpression. The aim of this work was to characterize epithelial oral and cervical cancer cells that express HR-HPV E6 and E7 oncoproteins. Transcriptomic assay using DNA microarrays revealed that PIR gene expression was detected in oral cells in an HR-HPV E6/E7-dependent manner. In addition, PIR was overexpressed in HPV-positive SiHa and Ca Ski cells, whereas it was undetectable in HPV-negative C33A cells. The PIR expression was dependent on functional HR-HPV E6 and E7 oncoproteins even though the E7 oncoprotein had higher activity to induce PIR overexpression in comparison with E6. In addition, using an siRNA for PIR silencing in oral cells ectopically expressing HR-HPV E6/E7, there was a significant increase in E-cadherin transcripts and a decrease in Vimentin, Slug, Zeb and Snail transcripts, suggesting that HR-HPV-induced PIR overexpression is involved in epithelial–mesenchymal transition. Furthermore, migration of PIR-silenced cells was significantly decreased. Finally, using inhibitors of some specific pathways, it was found that EGFR/ERK and PI3 K/AKT signalling pathways are important for E7-mediated PIR overexpression. It can be concluded that PIR gene expression is highly dependent on the expression of HR-HPV oncoproteins and is important for EMT regulation.

Oxidative stress in female cancers

Breast, cervical and ovarian cancers are highly prevalent in women worldwide. Environmental, hormonal and viral-related factors are especially relevant in the development of these tumors. These factors are strongly related to oxidative stress (OS) through the generation of reactive oxygen species (ROS). The OS is caused by an imbalance in the redox status of the organism and is literally defined as "an imbalance between ROS generation and its detoxification by biological system leading to impairment of damage repair by cell/tissue". The multistep progression of cancer suggests that OS is involved in cancer initiation, promotion and progression. In this review, we described the role of OS and the interplay with environmental, host and viral factors related to breast, cervical and ovarian cancers initiation, promotion and progression. In addition, the role of the natural antioxidant compound curcumin and other compounds for breast, cervical and ovarian cancers prevention/treatment is discussed.

Effect of curcumin on the cell surface markers CD44 and CD24 in breast cancer

Human breast cell lines are often characterized based on the expression of the cell surface markers CD44 and CD24. CD44 is a type I transmembrane glycoprotein that regulates cell adhesion and cell-cell, as well as cell-extracellular matrix interactions. CD24 is expressed in benign and malignant solid tumors and is also involved in cell adhesion and metastasis. The aim of the present study was to investigate the effects of curcumin on the surface expression of CD44 and CD24 in breast epithelial cell lines. An established breast cancer model derived from the MCF-10F cell line was used. The results revealed that curcumin decreased CD44 and CD24 gene and protein expression levels in MCF-10F (normal), Alpha5 (premalignant) and Tumor2 (malignant) cell lines compared with the levels in their counterpart control cells. Flow cytometry revealed that the CD44+/CD24+ cell subpopulation was greater than the CD44+/CD24- subpopulation in these three cell lines. Curcumin increased CD44+/CD24+ to a greater extent and decreased CD44+/CD24- subpopulations in the normal MCF-10F and the pre-tumorigenic Alpha5 cells, but had no significant effect on Tumor2 cells compared with the corresponding control cells. Conversely, curcumin increased CD44 and decreased CD24 gene expression in MCF-7 breast cancer cells, and decreased CD44 gene expression in MDA-MB-231 cell line, while CD24 was not present in these cells. Curcumin did not alter the CD44+/CD24+ or CD44+/CD24- subpopulations in the MCF-7 cell line. However, it increased CD44+/CD24+ and decreased CD44+/CD24- subpopulations in MDA-MB-231 cells. In breast cancer specimens from patients, normal tissues were negative for CD44 and CD24 expression, while benign lesions were positive for both markers, and malignant tissues were found to be negative for CD44 and positive for CD24 in most cases. In conclusion, these results indicated that curcumin may be used to improve the proportion of CD44+/CD24+ cells and decrease the proportion of CD44+/CD24- cells. Therefore, it may be suggested that curcumin decreased cancerous types of breast cells.

Metastatic genes targeted by an antioxidant in an established radiation- and estrogen-breast cancer model

Breast cancer remains the second most common disease worldwide. Radiotherapy, alone or in combination with chemotherapy, is widely used after surgery as a treatment for cancer with proven therapeutic efficacy manifested by reduced incidence of loco-regional and distant recurrences. However, clinical evidence indicates that relapses occurring after radiotherapy are associated with increased metastatic potential and poor prognosis in the breast. Among the anticarcinogenic and antiproliferative agents, curcumin is a well-known major dietary natural yellow pigment derived from the rhizome of the herb Curcuma longa (Zingiberaceae). The aim of the present study was to analyze the differential expression of metastatic genes in radiation- and estrogen-induced breast cancer cell model and the effect of curcumin on such metastatic genes in breast carcinogenesis. Expression levels of TGF-α and TGFβ1 genes were upregulated in MCF-10F and downregulated in Tumor2 cell lines treated with curcumin. Expression levels of other genes such as caspase 9 and collagen 4 A2 were upregulated in both MCF-10F and Tumor2-treated cell lines. Integrin α5 and cathepsin B and D decreased its expression in Tumor2, whereas E-Cadherin, c-myc and CD44 expressions were only increased in MCF-10F. It can be concluded that metastatic genes can be affected by curcumin in cancer progression and such substance can be used in breast cancer patients with advanced disease without side-effects commonly observed with therapeutic drugs.

Abstract 1478: Curcumin inhibits epithelial-mesenchymal transition and invasion in breast cancer cells by controlling miR-34a expression

Breast cancer in advanced stages tends to develop metastases and / or chemoresistance, in both cases therapeutic options are limited and have low probability of success, which represents the biggest obstacle in reducing mortality from this disease. There is a close connection between the Epithelial-Mesenchymal Transition (EMT) process of cancer cells and the acquisition of invasive and metastatic ability. Numerous EMT mediators have been described in cancer and among them miRNAs play a fundamental role in regulating such process, suggesting that it could be a therapeutic target to address this phenotype. Curcumin (diferuloylmethane) is a derivative compound of Curcuma longa that has therapeutic properties in various cancers as blocking initiation and tumor progression through its anti-inflammatory, antioxidant, proapoptotic, antiangiogenic and antimetastatic effects. The role of curcumin on EMT in non-cancerous breast cells MCF-10F and in breast cancer cell lines MCF-7 and MDA-MB-231 was evaluated. This work shows that in all these cell lines curcumin induced the expression of tumor suppressor microRNA miR-34a and repressed the expression of several genes involved in EMT and metastasis as Axl, Slug, Twist, N-cadherin, vimentin, fibronectin, among others. Consequently, curcumin inhibited the migration and invasiveness in these cells, irrespective of the expression of estrogen and progesterone receptors and p53 mutational status. Blockade of miR-34a by transfection with antagomiR-34a inhibited the effect of curcumin on EMT genes and on the migratory/invasive potential of cells indicating that miR-34a plays a central role in the Curcumin-mediated suppression of EMT and invasion. Therefore, results confirm the suppressive effect of curcumin on EMT and invasion in breast cancer cells, showing that such substance exerts this effect by inducing expression of miRNA miR-34a and consequently the repression of several of its target genes. Supported by Tarapacá University, Arica, Chile (GMC).

Citation Format: Marcela Gallardo, Richard Ponce-Cusi, Gloria M. Calaf. Curcumin inhibits epithelial-mesenchymal transition and invasion in breast cancer cells by controlling miR-34a expression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1478. doi:10.1158/1538-7445.AM2017-1478

Abstract 4806: Strategies to overcome the heterogeneity of tumor cells in breast cancer therapy

Breast carcinogenesis is a multistage process that involves mutations and alterations attributed to exposure to exogenous environmental substances and endogenous agents as female hormones. To overcome the heterogeneity of tumor cells in breast cancer therapy several strategies must be considered from the bench to clinical settings. It is proposed four strategies: Analysis to determine 1) Apoptosis, 2) Epithelial-mesenchymal transition (EMT), 3) CD44/CD24 gene and protein expression in cells derived from mammospheres and 4) MicroRNAs as miR34a and others by the effects of chemotherapeutic drugs (as pamidronate (Pam), 5-Fluorouracil (5-FU) and antioxidants as Curcumin (Cur) (diferuloylmethane) derived from Curcuma longa. Pam, a bisphosphonate is used in the treatment of breast cancer. 5-FU is a chemotherapeutic agent for the treatment of a variety of solid cancers that arrest cell cycle and induce apoptosis in cancer cells. We evaluated genes and proteins targeted by these drugs and antioxidants in a triple positive cell line, as MCF7 and a negative, MDA-MB-231 for hormonal receptors, respectively and in an in vitro breast cancer model induced by radiation and estrogen that was developed with a normal immortalized breast epithelial cell line, MCF-10F exposed to low doses of high LET (linear energy transfer) alpha particles (150 keV/μm) of radiation, and cultured in presence of 17β-estradiol. We used: i) MCF-10F, ii) Alpha3, a malignant non-tumorigenic, iii) Alpha5, a tumorigenic one and iv) Tumor2 cell line derived from Alpha5 injected into the nude mice. Previous results showed increased cell proliferation, anchorage independency, invasive capabilities and tumor formation in nude mice, microsatellite instability and loss of heterozygosity in chromosomes 6, 8, 11 and 17 and mutations of c-Ha-ras and Rho-A in Alpha5 and Tumor2 compared to the control MCF-10F and their counterparts. Pam, 5-FU and Cur inhibited migration and invasion in both cell lines, and also decreased c-Ha-ras, Rho-A, p53, and Cav-1 gene expression by RT-qPCR. These compounds also induced 1) apoptotic effect on Bcl-xL and Bax gene and protein expression and by flow cytometry; 2) changes in EMT markers such as Snail, Slug, Axl, 3) CD44/CD24 alterations and 4) target MicroRNAs as miR34a on different process. It can be concluded that strategies to overcome the heterogeneity of tumor cells can be used to interfere with genes involved in critical steps in breast carcinogenesis. Grant: Tarapacá University, Arica, Chile (GMC).

Short tittle: Strategies in breast cancer therapy

Citation Format: Gloria M. Calaf, Marcela Gallardo, Debasish Roy, Richard Ponce-Cusi. Strategies to overcome the heterogeneity of tumor cells in breast cancer therapy [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 4806. doi:10.1158/1538-7445.AM2017-4806

Association between non-melanoma and melanoma skin cancer rates, vitamin D and latitude

Vitamin D synthesis takes place in the skin due to solar ultraviolet-B (UVB) radiation. Several studies have shown the association between low sun exposure, non-melanoma skin cancer (NMSC) and a lack of vitamin D synthesis. Since such synthesis in the body depends on the exposure of the skin to solar UVB radiation (290-320 nm), experimental measurements of this type of solar radiation are important. Tarapaca University in Arica, Chile, established a solar UV radiation laboratory in 2006 and since then this laboratory has performed systematic experimental solar UVB measurements using a calibrated biometer instrument. The results, which are presented in the current study, showed the association between NMSC and MSC rates, and the time required to produce 1,000 IU vitamin D with latitudinal variation. Solar UV index (UVI) levels reported in 6 cities from the north to the south of Chile indicated that the UVI ratio of monthly mean values was 1.8 times higher in Arica than in Punta Arenas in January (summer in Chile), whereas it was 14 times higher in June (winter). This factor is an important consideration, since vitamin D synthesis is directly associated with the exposure of individuals to solar UVB radiation. A similar trend was observed in Antofagasta, Santiago, Concepcion, Valdivia and Punta Arenas. It can be concluded from these data that there is a direct association between NMSC rates and mortality, and UVB radiation, meaning that this type of cancer would not depend on vitamin D synthesis and therefore on calcium uptake. By contrast, MSC rates increased with decreased levels of vitamin D, and thus calcium uptake, in all cities, with the only exception being Punta Arenas.

Effect of curcumin and paclitaxel on breast carcinogenesis

Global cancer burden increased to 14.1 million new cases in 2012; and breast cancer is the most common cancer in women worldwide, with nearly 1.7 million new cases diagnosed in 2012. Curcumin is the major bioactive ingredient extracted from the rhizome of the plant Curcuma longa (turmeric). Paclitaxel is a microtubule-stabilizing agent originally isolated from the bark of Taxus brevifolia. Curcumin and paclitaxel were evaluated with two human breast cancer cell lines as the luminal MCF-7 and the basal-like MDA-MB-231 that are either positive or negative for hormonal receptors estrogen receptor, progesterone receptor and HER2, respectively. Results indicated that curcumin combined with paclitaxel decreased c-Ha-Ras, Rho-A, p53 and Bcl-xL gene expression in comparison to control and substances alone in MCF-7 cell line. These two substances alone and combined decreased gene expression of Bcl-2 and NF-κB. However, CCND1 increased when both substances were combined in MCF-7 cells. Such substances decreased Bcl-2 and increased Bax protein expression. However, curcumin alone decreased IκBα and Stat-3 gene expression. Paclitaxel alone and combined increased IκBα and Stat-3. Curcumin alone and combined with paclitaxel increased p53, Bid, caspase-3, caspase-8 and Bax gene expression in MDA-MB-231, whereas Bcl-xL decreased such expression in MDA-MB-231 cells. When paclitaxel and curcumin were combined the expression of Bcl-2 protein was decreased. However, either substance alone and combined increased Bax protein expression corroborating the apoptotic effect of these substances. It can be concluded that curcumin may be of considerable value in synergistic therapy of breast cancer reducing the associated toxicity with use of drugs.

Influence of doxorubicin on apoptosis and oxidative stress in breast cancer cell lines

Breast cancer is one of the leading causes of mortality among women worldwide due to aggressive behavior, early metastasis, resistance to existing chemotherapeutic agent and high mortality rate. Doxorubicin (Dox) is a powerful antitumoral drug. It is one of the most active agents for treatment of breast cancer. The aim of the present study was to evaluate the influence of Dox in apoptosis and oxidative stress in the breast cancer cell lines MCF-10F, MCF-7 and MDA-MB-231. These studies showed that Dox decreased anti-apoptotic Bcl-2 protein expression and affected oxidative stress by increasing hydrogen peroxide production and simultaneously decreasing NF-κB gene and protein expression in MCF-7, a tumorigenic triple-positive cell line. Results also indicated that Dox induced apoptosis by upregulating Bax, caspase-8 and caspase-3 and downregulation of Bcl-2 protein expression. On the contrary, ROS damage decreased by increasing SOD2 gene and protein expression and hydrogen peroxide production with parallel NF-κB protein expression decrease in MDA-MB-231, a tumorigenic triple-negative breast cancer cell line. It can be concluded that Dox activated apoptosis by inducing proteolytic processing of Bcl-2 family, caspases and simultaneously decreased oxidative stress by influencing ROS damage in MCF-7 and MDA-MB-231 cell lines.

Ras protein expression as a marker for breast cancer

Breast cancer, the most common neoplasm in women of all ages, is the leading cause of cancer-related mortality in women worldwide. Markers to help to predict the risk of progression and ultimately provide non-surgical treatment options would be of great benefit. At present, there are no available molecular markers to predict the risk of carcinoma in situ progression to invasive cancer; therefore, all women diagnosed with this type of malignancy must undergo surgery. Breast cancer is a heterogeneous complex disease, and different patients respond differently to different treatments. In breast cancer, analysis using immunohistochemical markers remains an essential component of routine pathological examinations, and plays an import role in the management of the disease by providing diagnostic and prognostic strategies. The aim of the present study was to identify a marker that can be used as a prognostic tool for breast cancer. For this purpose, we firstly used an established breast cancer model. MCF-10F, a spontaneously immortalized breast epithelial cell line was transformed by exposure to estrogen and radiation. MCF-10F cells were exposed to low doses of high linear energy transfer (LET) α particles (150 keV/μm) of radiation, and subsequently cultured in the presence of 17β-estradiol. Three cell lines were used: i) MCF-10F cells as a control; ii) Alpha5 cells, a malignant and tumorigenic cell line; and iii) Tumor2 cells derived from Alpha5 cells injected into nude mice. Secondly, we also used normal, benign and malignant breast specimens obtained from biopsies. The results revealed that the MCF-10F cells were negative for c-Ha-Ras protein expression; however, the Alpha5 and Tumor2 cell lines were positive for c-Ha-Ras protein expression. The malignant breast samples were also strongly positive for c-Ha-Ras expression. The findings of our study indicate that c-Ha-Ras protein expression may be used as a marker to predict the progression of breast cancer; this marker may also ultimately provide non-surgical treatment options for patients who are at a lower risk.

Curcumin and epithelial-mesenchymal transition in breast cancer cells transformed by low doses of radiation and estrogen

Breast cancer is a major cause of global mortality in women. Curcumin exerts anti-proliferative, anti-migratory and apoptotic effects. The aim of this study was to evaluate gene expression involved in epithelial-mesenchymal transition (EMT). An in vitro model was developed with the MCF-10F immortalized breast epithelial cell line exposed to low radiation doses of high LET (linear energy transfer) α-particles (150 keV/µm) and cultured in the presence of 17β-estradiol (estrogen). The following cell lines were used: i) MCF-10F, normal; ii) Alpha5, pre-tumorigenic, and iii) Tumor2 derived from Alpha5 injected into the nude mice. Our previous results have shown that Alpha5 and Tumor2 increased cell proliferation, anchorage independency, invasive capabilities and tumor formation in nude mice in comparison to control. Results indicated that curcumin decreased expression of EMT-related genes in Tumor2 cell line when compared to its counterpart as E-cadherin, N-cadherin, ZEB2, Twist1, Slug, Axl, vimentin, STAT-3, fibronectin; and genes p53 and caveolin-1, as well as apoptotic genes caspase-3, caspase-8, and others such as cyclin D1 and NFκB. All these changes induced a decrease in migratory and invasive capabilities of such a cell line. Thus, it seems that curcumin may impinge upon apoptosis and metastatic properties of the malignant cells exerting antitumor activity in breast cancer cells transformed by low doses of α-particles and estrogen in vitro.

Apoptotic effect of noscapine in breast cancer cell lines

Cancer is a public health problem in the world and breast cancer is the most frequently cancer in women. Approximately 15% of the breast cancers are triple-negative. Apoptosis regulates normal growth, homeostasis, development, embryogenesis and appropriate strategy to treat cancer. Bax is a protein pro-apoptotic enhancer of apoptosis in contrast to Bcl-2 with antiapoptotic properties. Initiator caspase-9 and caspase-8 are features of intrinsic and extrinsic apoptosis pathway, respectively. NF-κB is a transcription factor known to be involved in the initiation and progression of breast cancer. Noscapine, an alkaloid derived from opium is used as antitussive and showed antitumor properties that induced apoptosis in cancer cell lines. The aim of the present study was to determine the apoptotic effect of noscapine in breast cancer cell lines compared to breast normal cell line. Three cell lines were used: i) a control breast cell line MCF-10F; ii) a luminal-like adenocarcinoma triple-positive breast cell line MCF-7; iii) breast cancer triple-negative cell line MDA-MB-231. Our results showed that noscapine had lower toxicity in normal cells and was an effective anticancer agent that induced apoptosis in breast cancer cells because it increases Bax gene and protein expression in three cell lines, while decreases Bcl-xL gene expression, and Bcl-2 protein expression decreased in breast cancer cell lines. Therefore, Bax/Bcl-2 ratio increased in the three cell lines. This drug increased caspase-9 gene expression in breast cancer cell lines and caspase-8 gene expression increased in MCF-10F and MDA-MB-231. Furthermore, it increased cleavage of caspase-8, suggesting that noscapine-induced apoptosis is probably due to the involvement of extrinsic and intrinsic apoptosis pathways. Antiapoptotic gene and protein expression diminished and proapoptotic gene and protein expression increased noscapine-induced expression, probably due to decrease in NF-κB gene and protein expression and also by increase of IκBα gene expression induced by this drug.

Apoptotic activity of 5-fluorouracil in breast cancer cells transformed by low doses of ionizing α-particle radiation

Globally, breast cancer in women is the leading cause of cancer death. This fact has generated an interest to obtain insight into breast tumorigenesis and also to develop drugs to control the disease. Ras is a proto-oncogene that is activated as a response to extracellular signals. As a member of the Ras GTPase superfamily, Rho-A is an oncogenic and a critical component of signaling pathways leading to downstream gene regulation. In chemotherapy, apoptosis is the predominant mechanism by which cancer cells die. However, even when the apoptotic machinery remains intact, survival signaling may antagonize the cell death by signals. The aim of this study was to evaluate 5-fluorouracil (5-FU) in cells transformed by low doses of ionizing α-particle radiation, in breast cancer cell lines on these genes, as well as apoptotic activity. We used two cell lines from an in vitro experimental breast cancer model. The MCF-10F and Tumor2 cell lines. MCF-10F was exposed to low doses of high linear energy transfer (LET) α-particles radiation (150 keV/µm). Tumor2, is a malignant and tumorigenic cell line obtained from Alpha5 (60cGy+E/60cGy+E) injected into the nude mice. Results indicated that 5-FU decreased H-ras, Rho-A, p53, Stat1 and increased Bax gene expression in Tumor2 and decreased Rac1, Rho-A, NF-κB and increased Bax and caspase-3 protein expression in Tumor2. 5-FU decreased H-ras, Bcl-xL and NF-κB and increased Bax gene expression. 5-FU decreased Rac1, Rho-A protein expression and increased Bax and caspase-3 protein expression in MDA-MB-231. Flow cytometry indicated 21.5% of cell death in the control MCF-10F and 80% in Tumor2 cell lines. It can be concluded that 5-FU may exert apoptotic activity in breast cancer cells transformed by low doses of ionizing α-particles in vitro regulating genes of Ras family and related to apoptosis such as Bax, Bcl-xL and NF-κB expression.

Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead

Low-dose exposures to common environmental chemicals that are deemed safe individually may be combining to instigate carcinogenesis, thereby contributing to the incidence of cancer. This risk may be overlooked by current regulatory practices and needs to be vigorously investigated.

Lifestyle factors are responsible for a considerable portion of cancer incidence worldwide, but credible estimates from the World Health Organization and the International Agency for Research on Cancer (IARC) suggest that the fraction of cancers attributable to toxic environmental exposures is between 7% and 19%. To explore the hypothesis that low-dose exposures to mixtures of chemicals in the environment may be combining to contribute to environmental carcinogenesis, we reviewed 11 hallmark phenotypes of cancer, multiple priority target sites for disruption in each area and prototypical chemical disruptors for all targets, this included dose-response characterizations, evidence of low-dose effects and cross-hallmark effects for all targets and chemicals. In total, 85 examples of chemicals were reviewed for actions on key pathways/mechanisms related to carcinogenesis. Only 15% (13/85) were found to have evidence of a dose-response threshold, whereas 59% (50/85) exerted low-dose effects. No dose-response information was found for the remaining 26% (22/85). Our analysis suggests that the cumulative effects of individual (non-carcinogenic) chemicals acting on different pathways, and a variety of related systems, organs, tissues and cells could plausibly conspire to produce carcinogenic synergies. Additional basic research on carcinogenesis and research focused on low-dose effects of chemical mixtures needs to be rigorously pursued before the merits of this hypothesis can be further advanced. However, the structure of the World Health Organization International Programme on Chemical Safety ‘Mode of Action’ framework should be revisited as it has inherent weaknesses that are not fully aligned with our current understanding of cancer biology.

Mechanisms of environmental chemicals that enable the cancer hallmark of evasion of growth suppression

As part of the Halifax Project, this review brings attention to the potential effects of environmental chemicals on important molecular and cellular regulators of the cancer hallmark of evading growth suppression. Specifically, we review the mechanisms by which cancer cells escape the growth-inhibitory signals of p53, retinoblastoma protein, transforming growth factor-beta, gap junctions and contact inhibition. We discuss the effects of selected environmental chemicals on these mechanisms of growth inhibition and cross-reference the effects of these chemicals in other classical cancer hallmarks.

Abstract LB-086: Genes targeted by drugs and curcumin in a breast carcinogenesis model

Breast carcinogenesis is a multistage process that involves mutations and cellular phenotypic alterations attributed to exposure to exogenous environmental substances as well as endogenous agents as female hormones. Pamidronate (Pam), one of the nitrogen-containing bisphosphonates, is used in the treatment of bone metastases of breast cancer. It has recently been reported that it is also related to cell proliferation and apoptosis. 5-Fluorouracil (5-FU) is a chemotherapeutic agent for the treatment of a variety of solid cancers that arrest cell cycle and induce apoptosis in cancer cells. Curcumin (Cur) is an antioxidant known as a dietary natural yellow pigment derived from the rhizome of the herb Curcuma longa. The aim of this study was to evaluate genes that could be targeted by these drugs and curcumin in a breast carcinogenesis in vitro model induced by radiation and estrogen. Such model was developed with a normal immortalized breast epithelial cell line, MCF-10F that was exposed to low doses of high LET (linear energy transfer) alpha particles (150 keV/μm) of radiation, and cultured in presence of 17β-estradiol. This model consisted of the following cell lines: i) MCF-10F, ii) Alpha3, a malignant non-tumorigenic, iii) Alpha5, a tumorigenic one and iv) Tumor2, derived from Alpha5 injected into the nude mice. Previous results showed that Alpha5 and Tumor2 increased cell proliferation, presented anchorage independency, invasive capabilities and tumor formation in nude mice, as well as microsatellite instability and loss of heterozygosity in chromosomes 6, 8, 11 and 17 and mutations of c-Ha-ras and Rho-A among others. Pam, 5-FU and Cur were analyzed with MCF-10F by MTT indicating that the mean LD50 was 10, 2 and 30 μM after 48 hrs, respectively. Such substances inhibited migration and invasion in both Alpha5 and Tumor2 cell lines compared to the control MCF-10F and their counterparts, and also decreased c-Ha-ras, Rho-A, p53, Serpin-1 and Cav-1 gene expression in Alpha5 and significantly in Tumor2 cell lines by RT-qPCR. A significant apoptotic activity was observed by flow cytometry in Alpha5 and Tumor2 cell lines in comparison to control MCF-10F and their counterparts. These compounds had a direct antitumor and apoptotic effect on Bcl-xL and Bax by down-regulation of a transcription factor as NFĸB gene expression in Alpha5 and Tumor2 cell lines. It can be concluded that c-Ha-ras, RhoA, p53, Serpin-1 and Cav-1 genes were targeted by drugs and curcumin in a model transformed by low doses of alpha particles and estrogen. Such genes are involved in critical steps in breast carcinogenesis. Supported by FONDECYT #1120006 (GMC) and Ministry of Education (MINEDUC), Universidad de Tarapacá, Arica, Chile

Citation Format: Gloria M. Calaf, Debasish Roy, Richard Ponce-Cusi. Genes targeted by drugs and curcumin in a breast carcinogenesis model. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr LB-086. doi:10.1158/1538-7445.AM2015-LB-086

Ultraviolet light exposure, skin cancer risk and vitamin D production

The danger of overexposure to solar ultraviolet radiation has been widely reviewed since the 1980s due to the depletion of the ozone layer. However, the benefits of mild exposure of the skin to ultraviolet (UV) light have not been widely investigated. Numerous reports have demonstrated that an association exists between low light exposure to the sun, non-melanoma skin cancer and a lack of vitamin D synthesis. As vitamin D synthesis in the body depends on skin exposure to UVB radiation from the sun (wavelength, 290-320 nm), experimental measurements for this type of solar radiation are important. The present study analyzed data obtained from a laboratory investigating UV radiation from the sun at the University of Tarapacá (Arica, Chile), where systematic experimental UVB measurements had been performed using a calibrated biometer instrument since 2006. These data were compared with skin cancer data from the local population. The results demonstrated that the incidence of skin cancer systematically increased from 7.4 to 18.7 in men and from 10.0 to 21.7 in women between 2000 and 2006 in Arica, respectively; this increase may be due to multiple factors, including the lack of adequate levels of vitamin D in risk groups such as post-menopausal women and senior age. This marked increase may also be due to the high levels of UV radiation measured in this region throughout the year. However, it is not certain that the local population has adequate vitamin D levels, nor that their skin has been predominantly exposed to artificial light that does not allow adequate vitamin D synthesis. Thus, the current study presents the association between skin type IV, the time to induce solar erythema and the time required to produce 1,000 international units of vitamin D.

Antitumor activity of pamidronate in breast cancer cells transformed by low doses of α-particles and estrogen in vitro

Human breast cancer is a major cause of global morbidity and mortality in women and it is a process that involves numerous molecular and cellular alterations attributed to environmental substances and agents such as hormones. Bisphosphonates, such as pamidronate, are potent antiresorptive drugs used to the treatment of metabolic bone disease, exerting anti-proliferative, anti-migratory and apoptotic effects. The aim of this study was to evaluate gene and protein expression involved in these processes. An in vitro model was developed with the MCF-10F immortalized breast epithelial cell line exposed to low radiation doses of high LET (linear energy transfer) α-particles (150 keV/µm) and cultured in the presence of 17β-estradiol (estrogen). This model consisted of the following cell lines: i) MCF-10F, normal; ii) Alpha3, non-malignant; iii) Alpha5, pre-tumorigenic, and iv) Tumor2, derived from Alpha5 injected into the nude mice. Our previous results have shown that Alpha5 and Tumor2 increased cell proliferation, anchorage independency, invasive capabilities and tumor formation in nude mice in comparison to control. Expression of the gene (RT-qPCR) and protein (western blotting, flow cyto-metry) was measured. The results indicated that pamidronate decreased invasion, migration and Rho-A, c-Ha-ras, p53, Serpin-1, Caveolin-1, Bcl-xL and NFκB gene and protein expression. Thus, it seems that pamidronate may impinge upon cellular proliferation, invasion, metastasis and apoptosis and it may exert antitumor activity in breast cancer cells transformed by low doses of α-particles and estrogen in vitro.