The impact of low-dose carcinogens and environmental disruptors on tissue invasion and metastasis

Level of polychlorinated biphenyls in tumor and blood serum of breast cancer patients and control subjects from Punjab, Pakistan

The current study examined the level of Polychlorinated biphenyls (PCBs) in tumor and blood serum of female breast cancer patients and control individuals recruited from Punjab, Pakistan. Breast tumor and blood serum from 40 patients and only blood serum from ten control subjects were obtained and concentration of 32 PCB congeners was analyzed through Gas chromatography coupled with Mass spectrophotometry. Sociodemographic variables of the patients along with essential clinical and haematological parameters were taken as covariates. Tumor reflects the highest median (min-max) concentration (ng g-1 lw) of ƩPCBs at 115.94 (0.05-17.75) followed by 16.53 (0.09-2.94) and 5.24 (0.01-0.59) in blood serum of cancer patients and control group respectively. Median concentrations (ng g-1 lw) of non-dioxine like ƩPCBs were considerably higher at 83.04, 32.89 and 4.27 compared to 13.03 and 3.50 and 0.97 for dioxin like ƩPCBs in tumor, serum of breast cancer patients and control subjects respectively. PCB-87 was most dominant congeners in tumor followed by PCB-170 and -82 whereas PCB-28 and -52 reflected greatest contribution in serum of breast cancer patients. Blood haemoglobin, potassium and chloride ions showed significant positive whereas body mass index reflect inverse relationship when regressed with ƩPCBs in tumor. This pioneer study depicts elevated concentrations of PCBs in patients compared to control, reflecting potential positive association of PCBs with breast cancer which need further confirmation. We concluded that chronic exposure to PCBs might be associated with an increasing number of breast cancer incidences in developing countries like Pakistan, which should be further elucidated through detail in vitro and in vivo studies.

NLRP3 and cancer: Pathogenesis and therapeutic opportunities

More than a decade ago IL-1 blockade was suggested as an add-on therapy for the treatment of cancer. This proposal was based on the overall safety record of anti-IL-1 biologics and the anti-tumor properties of IL-1 blockade in animal models of cancer. Today, a new frontier in IL-1 activity regulation has developed with several orally active NLRP3 inhibitors currently in clinical trials, including cancer. Despite an increasing body of evidence suggesting a role of NLRP3 and IL-1-mediated inflammation driving cancer initiation, immunosuppression, growth, and metastasis, NLRP3 activation in cancer remains controversial. In this review, we discuss the recent advances in the understanding of NLRP3 activation in cancer. Further, we discuss the current opportunities for NLRP3 inhibition in cancer intervention with novel small molecules.

Mechanisms of breast cancer progression induced by environment-polluting aryl hydrocarbon receptor agonists

Breast cancer is the most common invasive malignancy among women worldwide and constitutes a complex and heterogeneous disease. Interest has recently grown in the role of the aryl hydrocarbon receptor (AhR) in breast cancer and the contribution of environment-polluting AhR agonists. Here, we present a literature review addressing AhR ligands, including pesticides hexachlorobenzene and chlorpyrifos, polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxins and dibenzofurans, polychlorinated biphenyls, parabens, and phthalates. The objectives of this review are a) to summarize recent original experimental, preclinical, and clinical studies on the biological mechanisms of AhR agonists which interfere with the regulation of breast endocrine functions, and b) to examine the biological effects of AhR ligands and their impact on breast cancer development and progression. We discuss biological mechanisms of action in cell viability, cell cycle, proliferation, epigenetic changes, epithelial to mesenchymal transition, and cell migration and invasion. In addition, we examine the effects of AhR ligands on angiogenic processes, metastasis, chemoresistance, and stem cell renewal. We conclude that exposure to AhR agonists stimulates pathways that promote breast cancer development and may contribute to tumor progression. Given the massive use of industrial and agricultural chemicals, ongoing evaluation of their effects in laboratory assays and preclinical studies in breast cancer at environmentally relevant doses is deemed essential. Likewise, awareness should be raised in the population regarding the most harmful toxicants to eradicate or minimize their use.

Incidence of malignancies after lung transplantation and their effect on the outcome. 26 years' experience

Background

Malignancy is a significant, life-limiting complication after lung transplantation (LuTx) and the second common long-term cause of death. We aimed to investigate its incidence and effect on the outcome.

Methods

This is a retrospective observational study. Between 1996 and 2022, n = 627 lung transplantations (LuTx) were performed in our department. We used our institutional database to identify recipients with malignancies after LuTx and examined the malignancies' incidence and mortality.

Results

N = 59 malignancies occurred in n = 55 (8.8%) LuTx recipients. The post-LTx malignancies incidence was 9.4% (59/627). We report the following rates based on their location: n = 17/55 (28,8% of all recipients diagnosed with malignancies) skin, n = 10/55 (16,95%) gastrointestinal, n = 9/55 (15,3%) respiratory, n = 5/55 (8,48%) lymphatic, n = 13/55 (23,6%) other, n = 5 (8,48%) multiple synchronous.During this study period, a total of n = 328 deaths after LuTx was determined. N = 29 (8,84% of all deaths) were malignancy induced, corresponding to a total malignancy-induced mortality of 4.6% (n = 29/627). The majority of deaths were attributed to GI adenocarcinoma and PTLD. Malignancies' origin, primary COPD diagnosis, type, and specific age group were significantly survival-related (p-values <0.05). The most affected organ was skin and showed the best prognosis. PTLD had the fastest and pancreatic the latest onset.

Conclusions

This is the first report of its kind in a large cohort of german LuTx recipients. The prevalence ranking of the three commonest malignancy were skin > colorectal > PTLD. Post-LTx malignancy was the second commonest cause of death. Further studies are needed, while post-LuTx malignomas remain a serious impairment of long-term LuTx survival.

Ursolic and oleanolic acids in combination therapy inhibit migration of colon cancer cells through down-regulation of the uPA/uPAR-dependent MMPs pathway

BACKGROUND

Colorectal cancer is one the most lethal cancers worldwide. Since chemotherapy is burdened with harmful effects, agents capable of enhancing the chemotherapeutic effect are being sought. Ursolic acid (UA) and oleanolic acid (OA) were analyzed for such properties. The aim of the study was to evaluate the ability of UA and OA administered individually and in combination with each other and/or a cytostatic drug camptothecin-11 (CPT-11) to limit the viability and migration of colorectal cancer cells.

MATERIALS AND METHODS

The cytotoxic effect of UA, OA and CPT-11 and impact on normal and cancer cell migration rate were assessed. Furthermore, the effect on factors crucial in cancer metastasis: MMP-2 and -9, uPA/uPAR, and E-cadherin were assessed with ELISA, Western Blotting and immunofluorescence assays. Statistical analysis was performed with One-Way Anova with Dunnett's test.

RESULTS

The studied compounds exhibited the most favorable properties, i.e. they reduced the viability and migration of cancer cells. Furthermore, the secretion, activity, and cellular level of cancer MMP-2 and -9 were decreased, as a result of uPA/uPAR down-regulation. The agents also increased the level of cellular E-cadherin. The effect of the studied agents on normal cells was milder.

CONCLUSIONS

The compounds exhibited stronger activity when administered in combination and, combined with CPT-11, enhanced anti-tumorigenic activity of the drug. The migration-limiting activity was based on down-regulation of the uPA/uPAR-dependent MMP pathway. Moreover, UA and OA exhibited a protective effect towards normal cells.

Oxidative stress in Hashimoto's thyroiditis: possible adjuvant therapies to attenuate deleterious effects

A number of studies have shown that oxidative stress is related to the pathogenesis of several immunological diseases, such as Hashimoto's thyroiditis (HT), although there is no plausible mechanism to explain it. Thus, we aimed at hypothesizing and providing some possible mechanisms linking oxidative stress to autoimmunity aspects and its implications for HT, as well as adjuvant therapeutic proposals to mitigate the deleterious effects. Our hypothesis is that deficient eating habits, autoimmune regulator gene predisposing gene, dysbiosis and molecular mimicry, unfolded proteins and stress in the endoplasmic reticulum, and thymus involution appear to be the main potential factors leading to HT oxidative stress. Likewise, we show that the use of minerals selenium and zinc, vitamins D and C, as well as probiotics, can be interesting adjuvant therapies for the control of oxidative damage and poor prognosis of HT. Further clinical trials are needed to understand the real beneficial and side effects of these supplements.

β-Caryophyllene Counteracts Chemoresistance Induced by Cigarette Smoke in Triple-Negative Breast Cancer MDA-MB-468 Cells

Exposure to cigarette smoke (CS) has been associated with an increased risk of fatal breast cancers and recurrence, along with chemoresistance and chemotherapy impairment. This strengthens the interest in chemopreventive agents to be exploited both in healthy and oncological subjects to prevent or repair CS damage. In the present study, we evaluated the chemopreventive properties of the natural sesquiterpene β-caryophyllene towards the damage induced by cigarette smoke condensate (CSC) in triple negative breast cancer MDA-MB-468 cells. Particularly, we assessed the ability of the sesquiterpene to interfere with the mechanisms exploited by CSC to promote cell survival and chemoresistance, including genomic instability, cell cycle progress, autophagy/apoptosis, cell migration and related pathways. β-Caryophyllene was found to be able to increase the CSC-induced death of MDA-MB-468 cells, likely triggering oxidative stress, cell cycle arrest and apoptosis; moreover, it hindered cell recovery, autophagy activation and cell migration; at last, a marked inhibition of the signal transducer and activator of transcription 3 (STAT3) activation was highlighted: this could represent a key mechanism of the chemoprevention by β-caryophyllene. Although further studies are required to confirm the in vivo efficacy of β-caryophyllene, the present results suggest a novel strategy to reduce the harmful effect of smoke in cancer patients and to improve the survival expectations in breast cancer women.

Role of the Synergistic Interactions of Environmental Pollutants in the Development of Cancer

There is a growing awareness that the large number of environmental pollutants we are exposed to on a daily basis are causing major health problems. Compared to traditional studies that focus on individual pollutants, there are relatively few studies on how pollutants mixtures interact. Several studies have reported a relationship between environmental pollutants and the development of cancer, even when pollutant levels are below toxicity reference values. The possibility of synergistic interactions between different pollutants could explain how even low concentrations can cause major health problems. These intricate that molecular interactions can occur through a wide variety of mechanisms, and our understanding of the physiological effects of mixtures is still limited. The purpose of this paper is to discuss recent reports that address possible synergistic interactions between different types of environmental pollutants that could promote cancer development. Our literature studies suggest that key biological pathways are frequently implicated in such processes. These include increased production of reactive oxygen species, activation by cytochrome P450, and aryl hydrocarbon receptor signaling, among others. We discuss the need to understand individual pathological vulnerability not only in relation to basic genetics and gene expression, but also in terms of measurable exposure to contaminants. We also mention the need for significant improvements in future studies using a multitude of disciplines, such as the development of high-throughput study models, better tools for quantifying pollutants in cancer patients, innovative pharmacological and toxicological studies, and high-efficiency computer analysis, which allow us to analyze the molecular mechanisms of mixtures.

Can Exposure to Environmental Pollutants Be Associated with Less Effective Chemotherapy in Cancer Patients?

Since environmental pollutants are ubiquitous and many of them are resistant to degradation, we are exposed to many of them on a daily basis. Notably, these pollutants can have harmful effects on our health and be linked to the development of disease. Epidemiological evidence together with a better understanding of the mechanisms that link toxic substances with the development of diseases, suggest that exposure to some environmental pollutants can lead to an increased risk of developing cancer. Furthermore, several studies have raised the role of low-dose exposure to environmental pollutants in cancer progression. However, little is known about how these compounds influence the treatments given to cancer patients. In this work, we present a series of evidences suggesting that environmental pollutants such as bisphenol A (BPA), benzo[a]pyrene (BaP), persistent organic pollutants (POPs), aluminum chloride (AlCl₃), and airborne particulate matter may reduce the efficacy of some common chemotherapeutic drugs used in different types of cancer. We discuss the potential underlying molecular mechanisms that lead to the generation of this chemoresistance, such as apoptosis evasion, DNA damage repair, activation of pro-cancer signaling pathways, drug efflux and action of antioxidant enzymes, among others.

The Parental Pesticide and Offspring's Epigenome Study: Towards an Integrated Use of Human Biomonitoring of Exposure and Effect Biomarkers

In Morocco, due to the lack of education and the presence of a counterfeit market, pesticides constitute a major problem to be addressed by occupational and environmental health agencies. This paper aims to introduce the PaPOE (Parental Pesticides and Offspring Epigenome) prospective study and its goals, to motivate the study rationale and design, and to examine comprehensively whether multi-residue exposure to commonly used pesticides could induce epigenetic alterations through the oxidative stress pathway. The PaPOE project includes a cross-sectional study assessing the occupational exposure among 300 farmworkers in Meknes, and initiates a birth cohort of 1000 pregnant women. Data and biological samples are collected among farmworkers, and throughout pregnancy, and at birth. Oxidative stress biomarkers include Glutathione, Malondialdehyde, and 8-OHdG. Global and gene-specific DNA methylation is assessed. The study began enrollment in 2019 and is ongoing. As of 30 June 2021, 300 farmworkers and 125 pregnant women have enrolled. The results are expected to showcase the importance of biomonitoring for understanding individual risks, and to identify a number of regions where DNA methylation status is altered in the pesticides-exposed population, paving the way for an integrated biomonitoring system in Morocco and Africa to assess environmental exposures and their long-term health consequences.

Exposure to airborne cadmium and breast cancer stage, grade and histology at diagnosis: findings from the E3N cohort study

Molecular studies suggest that cadmium due to its estrogenic properties, might play a role in breast cancer (BC) progression. However epidemiological evidence is limited. This study explored the association between long-term exposure to airborne cadmium and risk of BC by stage, grade of differentiation, and histological types at diagnosis. A nested case-control study of 4401 cases and 4401 matched controls was conducted within the French E3N cohort. A Geographic Information System (GIS)-based metric demonstrated to reliably characterize long-term environmental exposures was employed to evaluate airborne exposure to cadmium. Multivariable adjusted odds ratios (OR) and 95% confidence intervals (CI) were estimated using conditional logistic regression models. There was no relationship between cadmium exposure and stage of BC. Also, no association between cadmium exposure and grade of differentiation of BC was observed. However, further analyses by histological type suggested a positive association between cadmium and risk of invasive tubular carcinoma (ITC) BC [OR_{Q5 vs Q1} = 3.4 (95% CI 1.1-10.7)]. The restricted cubic spline assessment suggested a dose-response relationship between cadmium and ITC BC subtype. Our results do not support the hypothesis that airborne cadmium exposure may play a role in advanced BC risk, but suggest that cadmium may be associated with an increased risk of ITC.

Research progress on the association between environmental pollutants and the resistance mechanism of PARP inhibitors in ovarian cancer

The occurrence and progression of ovarian cancer are closely related to genetics and environmental pollutants. Poly(ADP-ribose) polymerase (PARP) inhibitors have been a major breakthrough in the history of ovarian cancer treatment. PARP is an enzyme responsible for post-translational modification of proteins and repair of single-stranded DNA damage. PARP inhibitors can selectively inhibit PARP function, resulting in a synthetic lethal effect on tumor cells defective in homologous recombination repair. However, with large-scale application, drug resistance also inevitably appears. For PARP inhibitors, the diversity and complexity of drug resistance mechanisms have always been difficult problems in clinical treatment. Herein, we mainly summarized the research progress of DNA damage repair and drug resistance mechanisms related to PARP inhibitors and the impact of environmental pollutants on DNA damage repair to aid the development prospects and highlight urgent problems to be solved.

Curation of cancer hallmark-based genes and pathways for in silico characterization of chemical carcinogenesis

Exposure to toxic substances in the environment is one of the most important causes of cancer. However, the time-consuming process for the identification and characterization of carcinogens is not applicable to a huge amount of testing chemicals. The data gaps make the carcinogenic risk uncontrollable. An efficient and effective way of prioritizing chemicals of carcinogenic concern with interpretable mechanism information is highly desirable. This study presents a curation work for genes and pathways associated with 11 hallmarks of cancer (HOCs) reported by the Halifax Project. To demonstrate the usefulness of the curated HOC data, the interacting HOC genes and affected HOC pathways of chemicals of the three carcinogen lists from IARC, NTP and EPA were analyzed using the in silico toxicogenomics ChemDIS system. Results showed that a higher number of affected HOCs were observed for known carcinogens than the other chemicals. The curated HOC data is expected to be useful for prioritizing chemicals of carcinogenic concern.

Database URL: The HOC database is available at https://github.com/hocdb-KMU-TMU/hocdb and the website of Database journal as Supplementary Data.

Risk of breast cancer associated with long-term exposure to benzo[a]pyrene (BaP) air pollution: Evidence from the French E3N cohort study

BACKGROUND

Benzo[a]pyrene (BaP) is an endocrine-disrupting pollutant formed during incomplete combustion of organic materials. It has been recognized as a reproductive and developmental toxicant, however epidemiological evidence of the long-term effect of ambient air BaP on breast cancer (BC) is limited. Thus we evaluated associations between ambient air BaP exposure and risk of BC, overall and according to menopausal status and molecular subtypes (estrogen receptor negative/positive (ER-/ER+) and progesterone receptor negative/positive (PR-/PR+)), stage and grade of differentiation of BC in the French E3N cohort study.

METHODS

Within a nested case-control study of 5222 incident BC cases and 5222 matched controls, annual BaP exposure was estimated using a chemistry-transport model (CHIMERE) and was assigned to the geocoded residential addresses of participants for each year during the 1990-2011 follow-up period. Multivariable conditional logistic regression models were used to estimate odds ratios (ORs) and 95% confidence intervals (CIs).

RESULTS

Overall, cumulative airborne BaP exposure was significantly associated with the overall risk of BC, for each 1 interquartile range (IQR) increase in the concentration levels of BaP (1.42 ng/m³), the OR = 1.15 (95% CI: 1.04-1.27). However, by menopausal status, the significant positive association remained only in women who underwent menopausal transition (i.e. premenopausal women at inclusion who became postmenopausal at diagnosis), OR per 1 IQR = 1.20 (95% CI: 1.03-1.40). By hormone receptor status, positive associations were observed for ER+, PR + and ER + PR + BC, with ORs = 1.17 (95% CI: 1.04-1.32), 1.16 (95% CI: 1.01-1.33), and 1.17 (95% CI: 1.01-1.36) per 1 IQR, respectively. There was also a borderline positive association between BaP and grade 3 BC (OR per 1 IQR = 1.15 (95% CI: 0.99-1.34).

CONCLUSIONS

We provide evidence of increased risk of BC associated with cumulative BaP exposure, which varied according to menopausal status, hormone receptor status, and grade of differentiation of BC. Our results add further epidemiological evidence to the previous experimental studies suggesting the adverse effects of BaP.

Environmental chemicals, breast cancer progression and drug resistance

Breast cancer (BC) is one of the most common causes of cancer in the world and the second leading cause of cancer deaths among women. Mortality is associated mainly with the development of metastases. Identification of the mechanisms involved in metastasis formation is, therefore, a major public health issue. Among the proposed risk factors, chemical environment and pollution are increasingly suggested to have an effect on the signaling pathways involved in metastatic tumor cells emergence and progression. The purpose of this article is to summarize current knowledge about the role of environmental chemicals in breast cancer progression, metastasis formation and resistance to chemotherapy. Through a scoping review, we highlight the effects of a wide variety of environmental toxicants, including persistent organic pollutants and endocrine disruptors, on invasion mechanisms and metastatic processes in BC. We identified the epithelial-to-mesenchymal transition and cancer-stemness (the stem cell-like phenotype in tumors), two mechanisms suspected of playing key roles in the development of metastases and linked to chemoresistance, as potential targets of contaminants. We discuss then the recently described pro-migratory and pro-invasive Ah receptor signaling pathway and conclude that his role in BC progression is still controversial. In conclusion, although several pertinent pathways for the effects of xenobiotics have been identified, the mechanisms of actions for multiple other molecules remain to be established. The integral role of xenobiotics in the exposome in BC needs to be further explored through additional relevant epidemiological studies that can be extended to molecular mechanisms.

Bisphenol A and polychlorinated biphenyls enhance the cancer stem cell properties of human ovarian cancer cells by activating the WNT signaling pathway

Cancer stem cells (CSCs) are a very small subpopulation that have stem-cell qualities, such as exhibiting self-renewal, immortality, and pluripotency, and the capability to differentiate into different tumor cell subtypes. CSCs contribute to tumor onset, expansion, metastasis, resistance and recurrence. Meanwhile, organic pollutants, including nonpersistent pollutants, such as bisphenol A (BPA), and persistent pollutants, such as polychlorinated biphenyls (PCBs), are toxic chemicals that can be readily ingested via dietary exposure and other exposure routes and can accumulate through the food chain. Many organic pollutants increase the risk of ovarian cancer depending on their estrogenic effects. Nonetheless, most previous studies have focused on the toxic effects of these pollutants on the proliferation, metastasis and development of ovarian cancer cells. However, little research has investigated the adverse effect of these pollutants on ovarian cancer stem cells. The current study found that BPA, PCB126 and PCB153 greatly enhanced the formation of cancer stem-like cell spheres of OVCAR-3 cells (human ovarian cancer cells) under low-dose exposure. In parallel, the CD44^highCD24^low cell subpopulation was increased in treated cells relative to untreated cells. Elevated expression of cancer stem cell markers, including ALDH1A1, CD133, SOX2, NANOG and OCT4, was demonstrated in treated cells compared to untreated cells. In summary, these data demonstrate that the oncogenic effects of pollutants can be evaluated according to changes in caner stem cell properties.

Dietary phytochemicals as the potential protectors against carcinogenesis and their role in cancer chemoprevention

Health-threatening consequences of carcinogen exposure are mediated via occurrence of electrophiles or reactive oxygen species. As a result, the accumulation of biomolecular damage leads to the cancer initiation, promotion or progression. Accordingly, there is an association between lifestyle factors including inappropriate diet or carcinogen formation during food processing, mainstream, second or third-hand tobacco smoke and other environmental or occupational carcinogens and malignant transformation. Nevertheless, increasing evidence supports the protective effects of naturally occurring phytochemicals against carcinogen exposure as well as carcinogenesis in general. Isolated phytochemicals or their mixtures present in the whole plant food demonstrate efficacy against malignancy induced by carcinogens widely spread in our environment. Phytochemicals also minimize the generation of carcinogenic substances during the processing of meat and meat products. Based on numerous data, selected phytochemicals or plant foods should be highly recommended to become a stable and regular part of the diet as the protectors against carcinogenesis.

Associations between persistent organic pollutants and risk of breast cancer metastasis

BACKGROUND

Breast cancer (BC) is a major public health concern with over 2 million new cases diagnosed and over 600,000 deaths in 2018 in women worldwide. When distant metastases are present at diagnosis, the 5-year survival rate is only 26%. Recent studies have suggested that persistent organic pollutants (POPs) that accumulate in adipose tissue (AT) can influence tumor phenotype and stimulate cellular processes important for metastasis such as invasion. We, therefore, tested the hypothesis that POP exposure is associated with BC metastasis.

METHODS

We conducted an exploratory case-control study in which the concentrations of 49 POPs were measured in both AT and serum samples from BC patients, with or without lymph node metastasis, who underwent partial or total mastectomies, lymph node biopsies and sampling of the adipocytic tumor microenvironment. Adjusted, unconditional logistic models were used to study the associations between the POP concentrations and the risk of metastasis and other hallmarks of cancer aggressiveness.

RESULTS

2.3.7.8-TCDD concentrations in AT are positively associated with the risk of metastasis in 43 patients who have BMIs equal or higher than 25 kg/m2 (odds ratio: 4.48 (1.32-20.71)). Furthermore, the concentrations of 2.3.7.8-TCDD and two coplanar PCBs (77&169) in AT also were positively associated with the risk of lymph node metastasis and the tumor size.

CONCLUSION

Our study suggests that 2.3.7.8-TCDD and some PCBs contribute to the development of tumor metastasis and other hallmarks of cancer aggressiveness. While these results should be considered with caution, this is the first study to identify such potential risk factors. Larger longitudinal studies are necessary to confirm our results. Clinical Trial Protocol Record: 2013-A00663-42.

Arsenic promotes the COX2/PGE2-SOX2 axis to increase the malignant stemness properties of urothelial cells

Chronic arsenic exposure is associated with the development of urothelial carcinoma of the bladder (UCB). To elucidate the contribution of arsenic exposure to urothelial cancer stem cell (CSC) generation, we established an in vitro stepwise malignant model transformed by chronically exposing human urothelial cells to arsenic. Using this model, we found that chronic arsenic exposure endows urothelial cells with malignant stemness properties including increased expression of stemness-related factors such as SOX2, sphere formation, self-renewal, invasion and chemoresistance. SOX2 was gradually and irreversibly overexpressed in line with acquired sphere-forming and self-renewal abilities. Following gene set enrichment analyses of arsenic-exposed and arsenic-unexposed cells, we found COX2 as an enriched gene for oncogenic signature. Mechanistically, arsenic-induced COX2/PGE2 increases SOX2 expression that eventually promotes malignant stem cell generation and repopulation. In urine samples from 90 subjects exposed to arsenic and 91 control subjects, we found a significant linear correlation between SOX2 and COX2 expression and the potential of SOX2 and COX2 expression as urinary markers to detect subjects exposed to arsenic. Furthermore, the combination marker yielded a high sensitivity for UCB detection in a separate cohort. Finally, our in vitro model exhibits basal-type molecular features and dual inhibition of EGFR and COX2 attenuated stem cell enrichment more efficiently than an EGFR inhibitor alone. In conclusion, the COX2/PGE2-SOX2 axis promotes arsenic-induced malignant stem cell transformation. In addition, our findings indicate the possible use of SOX2 and COX2 expression as urinary markers for the risk stratification and detection of UCB.

Filling the gap between chemical carcinogenesis and the hallmarks of cancer: A temporal perspective

BACKGROUND

Cancer is believed to arise through the perturbation of pathways and the order of pathway perturbation events can enhance understanding and evaluation of carcinogenicity. This order has not been examined so far, and this study aimed to fill this gap by attempting to gather evidence on the potential temporal sequence of events in carcinogenesis.

DESIGN

The methodology followed was to discuss first the temporal sequence of hallmarks of cancer from the point of view of pathological specimens of cancer (essentially branched mutations) and then to consider the hallmarks of cancer that one well-known carcinogen, benzo(a)pyrene, can modify.

RESULTS

Even though the sequential order of driving genetic alterations can vary between and within tumours, the main cancer pathways affected are almost ubiquitous and follow a generally common sequence: resisting cell death, insensitivity to antigrowth signals, sustained proliferation, deregulated energetics, replicative immortality and activation of invasion and metastasis. The first 3 hallmarks can be regarded as almost simultaneous while angiogenesis and avoiding immune destruction are perhaps the only hallmarks with a varying position in the above sequence.

CONCLUSIONS

Our review of hallmarks of cancer and their temporal sequence, based on mutational spectra in biopsies from different cancer sites, allowed us to propose a hypothetical temporal sequence of the hallmarks. This sequence can add molecular support to the evaluation of an agent as a carcinogen as it can be used as a conceptual framework for organising and evaluating the strength of existing evidence.

Delineating Potential Transcriptomic Association with Organochlorine Pesticides in the Etiology of Epithelial Ovarian Cancer

Background

Recent studies have shown that there is an increased risk of Epithelial Ovarian Cancer (EOC) with Organochlorine Pesticides (OCPs). However, the alteration in the gene expression profile has not been explored so far. The goal of the present study is to understand the probable molecular mechanism of OCPs toxicity towards discovery of dysregulation of signaling pathway associated with differential gene expression and candidate transcriptomic set of markers in the pathophysiology of EOC in OCPs exposed population.

Methods

The OCP levels were estimated by gas chromatography and whole genome differential expression study was carried out using expression microarray and candidate genes were validated using Real time RT-PCR.

Results

Significant level of OCP residues such as β-hexachlorocyclohexane (β-HCH), Heptachlor, Heptachlor epoxide B (HTEB), dichlorodiphenyldichloroethylene (p'p'-DDE) and endosulfan-I was found between healthy and EOC patients. The transcriptome profile of several genes revealed regulation of various important cellular processes such as metabolism, inflammation, cytoskeleton dysregulation of TGF and WNT pathway in EOC cases with high OCPs.

Conclusion

This study provides the first evidence showing that differentially expressed genes and dysregulation of signaling pathways might be associated with significant level of OCPs exposure in ovary tissue of epithelial ovarian cancer patients. Moreover, significant correlation of these genes with OCPs revealed that OCPs exposure played vital role in dysregulation of related pathways in the etiology of EOC.

Endocrine Disruptors Leading to Obesity and Related Diseases

The review aims to comprehensively present the impact of exposure to endocrine disruptors (EDs) in relation to the clinical manifestation of obesity and related diseases, including diabetes mellitus, metabolic syndrome, cardiovascular diseases, carcinogenesis and infertility. EDs are strong participants in the obesity epidemic scenery by interfering with cellular morphological and biochemical processes; by inducing inflammatory responses; and by presenting transcriptional and oncogenic activity. Obesity and lipotoxicity enhancement occur through reprogramming and/or remodeling of germline epigenome by exposure to EDs. Specific population groups are vulnerable to ED exposure due to current dietary and environmental conditions. Obesity, morbidity and carcinogenicity induced by ED exposure are an evolving reality. Therefore, a new collective strategic approach is deemed essential, for the reappraisal of current global conditions pertaining to energy management.

A Perspective Discussion on Rising Pesticide Levels and Colon Cancer Burden in Brazil

Agriculture is a mainstay of many developing countries’ economy, such as Brazil. According to the Food and Agriculture Organization of the United Nations, Brazil is the major global consumer of pesticides. Irrespective of the fact that the International Agency for Research on Cancer suggests that pesticides promote human cancer risk, a prospective study reports that colorectal cancer (CRC) burden will increase in developing countries by approximately 60% in the coming decades. Here, we review the literature and public data from the Brazilian Federal Government to explore why pesticides levels and new cases of colon cancer (CC) are rising rapidly in the country. CC incidence is the second most common malignancy in men and women in the South and the Southeast of Brazil. However, while these regions have almost doubled their pesticide levels and CC mortality in 14 years, the amount of sold pesticides increased 5.2-fold with a corresponding 6.2-fold increase in CC mortality in Northern and Northeastern states. Interestingly, mortality from endocrine, nutritional, and metabolic diseases are rapidly increasing, in close resemblance with the pesticide detection levels in food. Taken together, we discuss the possibility that pesticides might alter the risk of CC.

Cellular acidification as a new approach to cancer treatment and to the understanding and therapeutics of neurodegenerative diseases

During the last few years, the understanding of the dysregulated hydrogen ion dynamics and reversed proton gradient of cancer cells has resulted in a new and integral pH-centric paradigm in oncology, a translational model embracing from cancer etiopathogenesis to treatment. The abnormalities of intracellular alkalinization along with extracellular acidification of all types of solid tumors and leukemic cells have never been described in any other disease and now appear to be a specific hallmark of malignancy. As a consequence of this intracellular acid-base homeostatic failure, the attempt to induce cellular acidification using proton transport inhibitors and other intracellular acidifiers of different origins is becoming a new therapeutic concept and selective target of cancer treatment, both as a metabolic mediator of apoptosis and in the overcoming of multiple drug resistance (MDR). Importantly, there is increasing data showing that different ion channels contribute to mediate significant aspects of cancer pH regulation and etiopathogenesis. Finally, we discuss the extension of this new pH-centric oncological paradigm into the opposite metabolic and homeostatic acid-base situation found in human neurodegenerative diseases (HNDDs), which opens novel concepts in the prevention and treatment of HNDDs through the utilization of a cohort of neural and non-neural derived hormones and human growth factors.

Low-Dose Mixture Hypothesis of Carcinogenesis Workshop: Scientific Underpinnings and Research Recommendations

BACKGROUND

The current single-chemical-as-carcinogen risk assessment paradigm might underestimate or miss the cumulative effects of exposure to chemical mixtures, as highlighted in recent work from the Halifax Project. This is particularly important for chemical exposures in the low-dose range that may be affecting crucial cancer hallmark mechanisms that serve to enable carcinogenesis.

OBJECTIVE

Could ongoing low-dose exposures to a mixture of commonly encountered environmental chemicals produce effects in concert that lead to carcinogenesis? A workshop held at the NIEHS in August 2015 evaluated the scientific support for the low-dose mixture hypothesis of carcinogenesis and developed a research agenda. Here we describe the science that supports this novel theory, identify knowledge gaps, recommend future methodologies, and explore preventative risk assessment and policy decision-making that incorporates cancer biology, environmental health science, translational toxicology, and clinical epidemiology.

DISCUSSION AND CONCLUSIONS

The theoretical merits of the low-dose carcinogenesis hypothesis are well founded with clear biological relevance, and therefore, the premise warrants further investigation. Expert recommendations include the need for better insights into the ways in which noncarcinogenic constituents might combine to uniquely affect the process of cellular transformation (in vitro) and environmental carcinogenesis (in vivo), including investigations of the role of key defense mechanisms in maintaining transformed cells in a dormant state. The scientific community will need to acknowledge limitations of animal-based models in predicting human responses; evaluate biological events leading to carcinogenesis both spatially and temporally; examine the overlap between measurable cancer hallmarks and characteristics of carcinogens; incorporate epigenetic biomarkers, in silico modelling, high-performance computing and high-resolution imaging, microbiome, metabolomics, and transcriptomics into future research efforts; and build molecular annotations of network perturbations. The restructuring of many existing regulatory frameworks will require adequate testing of relevant environmental mixtures to build a critical mass of evidence on which to base policy decisions. Citation: Miller MF, Goodson WH III, Manjili MH, Kleinstreuer N, Bisson WH, Lowe L. 2017. Low-Dose Mixture Hypothesis of Carcinogenesis Workshop: scientific underpinnings and research recommendations. Environ Health Perspect 125:163-169; http://dx.doi.org/10.1289/EHP411.

Natural Compounds As Modulators of Non-apoptotic Cell Death in Cancer Cells

Cell death is an innate capability of cells to be removed from microenvironment, if and when they are damaged by multiple stresses. Cell death is often regulated by multiple molecular pathways and mechanism, including apoptosis, autophagy, and necroptosis. The molecular network underlying these processes is often intertwined and one pathway can dynamically shift to another one acquiring certain protein components, in particular upon treatment with various drugs. The strategy to treat human cancer ultimately relies on the ability of anticancer therapeutics to induce tumor-specific cell death, while leaving normal adjacent cells undamaged. However, tumor cells often develop the resistance to the drug-induced cell death, thus representing a great challenge for the anticancer approaches. Numerous compounds originated from the natural sources and biopharmaceutical industries are applied today in clinics showing advantageous results. However, some exhibit serious toxic side effects. Thus, novel effective therapeutic approaches in treating cancers are continued to be developed. Natural compounds with anticancer activity have gained a great interest among researchers and clinicians alike since they have shown more favorable safety and efficacy then the synthetic marketed drugs. Numerous studies in vitro and in vivo have found that several natural compounds display promising anticancer potentials. This review underlines certain information regarding the role of natural compounds from plants, microorganisms and sea life forms, which are able to induce non-apoptotic cell death in tumor cells, namely autophagy and necroptosis.

Advances in Understanding How Heavy Metal Pollution Triggers Gastric Cancer

With the development of industrialization and urbanization, heavy metals contamination has become a major environmental problem. Numerous investigations have revealed an association between heavy metal exposure and the incidence and mortality of gastric cancer. The mechanisms of heavy metals (lead, cadmium, mercury, chromium, and arsenic) contamination leading to gastric cancer are concluded in this review. There are four main potential mechanisms: (1) Heavy metals disrupt the gastric mucosal barrier by decreasing mucosal thickness, mucus content, and basal acid output, thereby affecting the function of E-cadherin and inducing reactive oxygen species (ROS) damage. (2) Heavy metals directly or indirectly induce ROS generation and cause gastric mucosal and DNA lesions, which subsequently alter gene regulation, signal transduction, and cell growth, ultimately leading to carcinogenesis. Exposure to heavy metals also enhances gastric cancer cell invasion and metastasis. (3) Heavy metals inhibit DNA damage repair or cause inefficient lesion repair. (4) Heavy metals may induce other gene abnormalities. In addition, heavy metals can induce the expression of proinflammatory chemokine interleukin-8 (IL-8) and microRNAs, which promotes tumorigenesis. The present review is an effort to underline the human health problem caused by heavy metal with recent development in order to garner a broader perspective.