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Fulltext The potential for chemical mixtures from the environment to enable the cancer hallmark of sustained proliferative signalling

Engström W, Darbre P, Eriksson S, Gulliver L, Hultman T, Karamouzis MV, et al.

Carcinogenesis, 2015 Jun;36 Suppl 1:S38-60.
PMID: 26106143 DOI: 10.1093/carcin/bgv030

The aim of this work is to review current knowledge relating the established cancer hallmark, sustained cell proliferation to the existence of chemicals present as low dose mixtures in the environment. Normal cell proliferation is under tight control, i.e. cells respond to a signal to proliferate, and although most cells continue to proliferate into adult life, the multiplication ceases once the stimulatory signal disappears or if the cells are exposed to growth inhibitory signals. Under such circumstances, normal cells remain quiescent until they are stimulated to resume further proliferation. In contrast, tumour cells are unable to halt proliferation, either when subjected to growth inhibitory signals or in the absence of growth stimulatory signals. Environmental chemicals with carcinogenic potential may cause sustained cell proliferation by interfering with some cell proliferation control mechanisms committing cells to an indefinite proliferative span.

Matched MeSH terms: Neoplasms/chemically induced*
Fulltext Endometrial carcinoma can develop in patients on tamoxifen therapy

Omar SZ, Sivanesaratnam V

Med J Malaysia, 1999 Jun;54(2):280-2.
PMID: 10972045
Matched MeSH terms: Endometrial Neoplasms/chemically induced*
Areca nut: a review

Arjungi KN

Arzneimittelforschung, 1976;26(5):951-6.
PMID: 786304

Areca cattechu Linn is commonly known as areca nut or betel nut. It is a very widely cultivated plant in eastern countries like India, Bangladesh, Ceylon, Malaya, the Philippines and Japan. The importance of this nut is due to its use for chewing purposes. It had an important place as a pharmaceutical in Ayurveda--the ancient Indian system of medicine--also in the Chinese medicinal practices. The pharmaceutical importance of areca nut is due to the presence of an alkaloid, arecoline. Synthetic arecoline hydrobromide is also shown to possess numerous pharmacological properties. Chewing of "betel quid" or areca nut is a typical oriental habit. Betel quid comprises betel leaf, areca nut, catechu, lime and sometimes also tobacco. It is shown that there exists a correlationship between betel quid or areca nut chewing habit and oral cancer. A number of investigators have been able to produce cellular changes such as leukoplakia by application of betel quid or areca nut extract to the buccal mucosa of different animal.

Matched MeSH terms: Mouth Neoplasms/chemically induced
Effects of different mycotoxins on humans, cell genome and their involvement in cancer (Review)

Ahmed Adam MA, Tabana YM, Musa KB, Sandai DA

Oncol Rep, 2017 Mar;37(3):1321-1336.
PMID: 28184933 DOI: 10.3892/or.2017.5424

The chemical nature of most of the mycotoxins makes them highly liposoluble compounds that can be absorbed from the site of exposure such as from the gastrointestinal and respiratory tract to the blood stream where it can be dissimilated throughout the body and reach different organs such as the liver and kidneys. Mycotoxins have a strong tendency and ability to penetrate the human and animal cells and reach the cellular genome where it causes a major mutagenic change in the nucleotide sequence which leads to strong and permanent defects in the genome. This defect will eventually be transcribed, translated and lead to the development of cancer. In this review, the chemical and physical nature of mycotoxins, the action of mycotoxins on the cellular genome and its effect on humans, mycotoxins and their carcinogenicity and mycotoxins research gaps are discussed, and new research areas are suggested. The research review posed various questions. What are the different mycotoxins that can cause cancer, what is the role of mycotoxins in causing cancer and what types of cancers can be caused by mycotoxins? These questions have been selected due to the significant increase in the mycotoxin contamination and the cancer incidence rate in the contemporary world. By revealing and understanding the role of mycotoxins in developing cancer, measures to reduce the risks and incidents of cancer could be taken.

Matched MeSH terms: Neoplasms/chemically induced
Fulltext Assessing the carcinogenic potential of low-dose exposures to chemical mixtures in the environment: the challenge ahead

Goodson WH, Lowe L, Carpenter DO, Gilbertson M, Manaf Ali A, Lopez de Cerain Salsamendi A, et al.

Carcinogenesis, 2015 Jun;36 Suppl 1:S254-96.
PMID: 26106142 DOI: 10.1093/carcin/bgv039

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.

Matched MeSH terms: Neoplasms/chemically induced*
Fulltext Chemopreventive Properties and Toxicity of Kelulut Honey in Sprague Dawley Rats Induced with Azoxymethane

Saiful Yazan L, Muhamad Zali MF, Mohd Ali R, Zainal NA, Esa N, Sapuan S, et al.

Biomed Res Int, 2016;2016:4036926.
PMID: 27525267 DOI: 10.1155/2016/4036926

Ethnopharmacological Relevance. Colon cancer has been a major problem worldwide. Kelulut honey (KH) is produced by the stingless bees from Trigona species and has strong antioxidant activities that could be one of the potential chemopreventive agents from natural resources. Aim of This Study. This study investigated the chemopreventive properties and toxicity of KH in Sprague Dawley rats induced with azoxymethane (AOM). Material and Method. Twenty-four male Sprague Dawley rats aged 5 weeks were divided into 4 groups: (G1) untreated group not induced with AOM, (G2) untreated group induced with AOM, (G3) treated group induced with AOM, and (G4) treated group not induced with AOM. Injection of AOM (15 mg/kg) was via intraperitoneal route once a week for two subsequent weeks. The treatment groups were given oral administration of KH (1183 mg/kg body weight) twice daily for 8 weeks. Results. Treatment with KH significantly reduced the total number of aberrant crypt foci (ACF) and aberrant crypts (AC) and crypt multiplicity. KH was not toxic to the animals since the level of blood profile parameters, liver enzymes, and kidney functions was in normal range. Conclusions. The current finding shows that KH has chemopreventive properties in rats induced with colorectal cancer and also was found not toxic towards the animals.

Matched MeSH terms: Colorectal Neoplasms/chemically induced
Prevention of oral carcinogenesis in rats by Dracaena cinnabari resin extracts

Al-Afifi N, Alabsi A, Kaid F, Bakri M, Ramanathan A

Clin Oral Investig, 2019 May;23(5):2287-2301.
PMID: 30291495 DOI: 10.1007/s00784-018-2685-6

OBJECTIVES: In vivo study was performed to determine the chemopreventive efficacy of the DC resin methanol extract on a 4-nitroquinoline-1-oxide (4NQO) oral cancer animal model.
MATERIALS AND METHODS: This study involves administration of 4NQO solution for 8 weeks alone (cancer induction) or with Dracaena cinnabari (DC) extract at 100, 500, and 1000 mg/kg. DC extract administration started 1 week before exposure until 1 week after the carcinogen exposure was stopped. All rats were sacrificed after 22 weeks, and histological analysis was performed to assess any incidence of pathological changes. Immunohistochemical expressions of selected tumor marker antibodies were analyzed using an image analyzer computer system, and the expression of selected genes involved in apoptosis and proliferative mechanism related to oral cancer were evaluated using RT2-PCR.
RESULTS: The incidence of OSCC decreased with the administration of DC extract at 100, 500, and 1000 mg/kg compared to the induced cancer group. The developed tumor was also observed to be smaller when compared to the induced cancer group. The DC 1000 mg/kg group inhibits the expression of Cyclin D1, Ki-67, Bcl-2, and p53 proteins. It was observed that DC 1000 mg/kg induced apoptosis by upregulation of Bax and Casp3 genes and downregulation of Tp53, Bcl-2, Cox-2, Cyclin D1, and EGFR genes when compared to the induced cancer group.
CONCLUSIONS: The data indicated that systemic administration of the DC resin methanol extract has anticarcinogenic potency on oral carcinogenesis.
CLINICAL RELEVANCE: Chemoprevention with DC resin methanol extract may significantly reduce morbidity and possibly mortality from OSCC.

Matched MeSH terms: Mouth Neoplasms/chemically induced
Genetic, epigenetic, and lineage-directed mechanisms in benzene-induced malignancies and hematotoxicity targeting hematopoietic stem cells niche

Dewi R, Hamid ZA, Rajab NF, Shuib S, Razak SA

Hum Exp Toxicol, 2020 May;39(5):577-595.
PMID: 31884827 DOI: 10.1177/0960327119895570

Benzene is a known hematotoxic and leukemogenic agent with hematopoietic stem cells (HSCs) niche being the potential target. Occupational and environmental exposure to benzene has been linked to the incidences of hematological disorders and malignancies. Previous studies have shown that benzene may act via multiple modes of action targeting HSCs niche, which include induction of chromosomal and micro RNA aberrations, leading to genetic and epigenetic modification of stem cells and probable carcinogenesis. However, understanding the mechanism linking benzene to the HSCs niche dysregulation is challenging due to complexity of its microenvironment. The niche is known to comprise of cell populations accounted for HSCs and their committed progenitors of lymphoid, erythroid, and myeloid lineages. Thus, it is fundamental to address novel approaches via lineage-directed strategy to elucidate precise mechanism involved in benzene-induced toxicity targeting HSCs and progenitors of different lineages. Here, we review the key genetic and epigenetic factors that mediate hematotoxicological effects by benzene and its metabolites in targeting HSCs niche. Overall, the use of combined genetic, epigenetic, and lineage-directed strategies targeting the HSCs niche is fundamental to uncover the key mechanisms in benzene-induced hematological disorders and malignancies.

Matched MeSH terms: Neoplasms/chemically induced*
Fulltext Metabolic reprogramming and dysregulated metabolism: cause, consequence and/or enabler of environmental carcinogenesis?

Robey RB, Weisz J, Kuemmerle NB, Salzberg AC, Berg A, Brown DG, et al.

Carcinogenesis, 2015 Jun;36 Suppl 1(Suppl 1):S203-31.
PMID: 26106140 DOI: 10.1093/carcin/bgv037

Environmental contributions to cancer development are widely accepted, but only a fraction of all pertinent exposures have probably been identified. Traditional toxicological approaches to the problem have largely focused on the effects of individual agents at singular endpoints. As such, they have incompletely addressed both the pro-carcinogenic contributions of environmentally relevant low-dose chemical mixtures and the fact that exposures can influence multiple cancer-associated endpoints over varying timescales. Of these endpoints, dysregulated metabolism is one of the most common and recognizable features of cancer, but its specific roles in exposure-associated cancer development remain poorly understood. Most studies have focused on discrete aspects of cancer metabolism and have incompletely considered both its dynamic integrated nature and the complex controlling influences of substrate availability, external trophic signals and environmental conditions. Emerging high throughput approaches to environmental risk assessment also do not directly address the metabolic causes or consequences of changes in gene expression. As such, there is a compelling need to establish common or complementary frameworks for further exploration that experimentally and conceptually consider the gestalt of cancer metabolism and its causal relationships to both carcinogenesis and the development of other cancer hallmarks. A literature review to identify environmentally relevant exposures unambiguously linked to both cancer development and dysregulated metabolism suggests major gaps in our understanding of exposure-associated carcinogenesis and metabolic reprogramming. Although limited evidence exists to support primary causal roles for metabolism in carcinogenesis, the universality of altered cancer metabolism underscores its fundamental biological importance, and multiple pleiomorphic, even dichotomous, roles for metabolism in promoting, antagonizing or otherwise enabling the development and selection of cancer are suggested.

Matched MeSH terms: Neoplasms/chemically induced*
Fulltext Estimation of arecoline contents in commercial areca (betel) nuts and its relation to oral precancerous lesions

Awang MN

Singapore Med J, 1986 Aug;27(4):317-20.
PMID: 3798144

Areca catechu (betel) nut is widely used as a chewing agent. The nut alkaloids have been implicated in the pathogenesis of oral precancerous lesions. Quantitative analysis of the chloroform extracts by gas-liquid chromatography of ten commercial nut samples from Bombay have shown a wide variations In their arecoline contents (0% - 1.4%; mean: 0.7%). Nut samples of Identical processing method also vary in their arecoline levels. These variations were suggested to be due to the difference In the raw materials and processing methods. Comparisons were made between the arecoline contents and the Incidence of oral precancerous lesions from the present studies and also from those of Kerala and Mysore. It was concluded that the difference in nut arecoline contents not only reflect their appeal, potency but also influence upon the incidence of these diseases.

Matched MeSH terms: Mouth Neoplasms/chemically induced*
Fertility control and the risk of gynecological malignancies

Sivanesaratnam V

Obstet Gynecol Surv, 1991 Mar;46(3):131-7.
PMID: 1849623
Matched MeSH terms: Breast Neoplasms/chemically induced*; Trophoblastic Neoplasms/chemically induced