Occupational exposure to magnetic fields and breast cancer among Canadian men

Houttuynia cordata Thunb. Hexane fraction induces MDA-MB-231 cell apoptosis via caspases, ER stress, cell cycle arrest and attenuated Akt/ERK signaling

Houttuynia cordata Thunb. (HCT) is a perennial plant used in traditional Thai medicine for many centuries. This study aimed to investigate the antiproliferative effect of the hexane fraction, which has not been explored before. HCT ethanol extract (crude extract) was sequentially fractionated to obtain a hexane (H) fraction. GC-MS was used to determine the phytochemicals. The H fraction consisted of lipids, mainly α-linolenic acid and some terpenoids. MTT assay was used to determine the cytotoxic effects of H fraction in MCF-7, MDA-MB-231, NIH3T3 and PBMCs. The mode of cell death and cell cycle analysis were determined by flow cytometry. The mechanisms of cell death were defined by mitochondrial transmembrane potential (MTP) reduction and activation of caspase-3, -8 and -9. The expression levels of the Bcl-2 family, cell cycle-related, endoplasmic reticulum (ER) stress-associated proteins; and Akt/ERK signaling molecules were investigated by immunoblotting. The H fraction was toxic to MDA-MB-231 more than MCF-7 cells but not to NIH3T3 and PBMCs. The growth of MDA-MB-231 cells was inhibited through apoptosis. MTP was disrupted whereas caspase-3, -8 and -9 were activated. The expression of pro-apoptotic Bax and Bak was upregulated, while Bid and anti-apoptotic Bcl-xL proteins were downregulated. Cyclin D1 and CDK4 levels were downregulated. The cell cycle was arrested at G1. Moreover, GRP78 and CHOP elevation indicated ER stress-mediated pathway. The expression ratio of pAkt/Akt and pERK/ERK were reduced. Taken together, the molecular mechanisms of MDA-MB-231 cell apoptosis were via intrinsic/extrinsic pathways, cell cycle arrest, ER stress and abrogation of Akt/ERK survival pathways. According to the most current research, the H fraction may be used as an adjuvant in the BC treatment; however, before the anticancer strategy can be applied to patients, it is important to determine each active compound's effects in cell lines and in vivo when compared with a combined mixture.

Magnetic Fields and Cancer: Epidemiology, Cellular Biology, and Theranostics

Humans are exposed to a complex mix of man-made electric and magnetic fields (MFs) at many different frequencies, at home and at work. Epidemiological studies indicate that there is a positive relationship between residential/domestic and occupational exposure to extremely low frequency electromagnetic fields and some types of cancer, although some other studies indicate no relationship. In this review, after an introduction on the MF definition and a description of natural/anthropogenic sources, the epidemiology of residential/domestic and occupational exposure to MFs and cancer is reviewed, with reference to leukemia, brain, and breast cancer. The in vivo and in vitro effects of MFs on cancer are reviewed considering both human and animal cells, with particular reference to the involvement of reactive oxygen species (ROS). MF application on cancer diagnostic and therapy (theranostic) are also reviewed by describing the use of different magnetic resonance imaging (MRI) applications for the detection of several cancers. Finally, the use of magnetic nanoparticles is described in terms of treatment of cancer by nanomedical applications for the precise delivery of anticancer drugs, nanosurgery by magnetomechanic methods, and selective killing of cancer cells by magnetic hyperthermia. The supplementary tables provide quantitative data and methodologies in epidemiological and cell biology studies. Although scientists do not generally agree that there is a cause-effect relationship between exposure to MF and cancer, MFs might not be the direct cause of cancer but may contribute to produce ROS and generate oxidative stress, which could trigger or enhance the expression of oncogenes.

Combined effect of co-exposure to di (2-ethylhexyl) phthalates and 50-Hz magnetic-fields on promoting human amniotic cells proliferation

Di (2-ethylhexyl) phthalate (DEHP) and extremely low-frequency electromagnetic fields (ELF-EMFs) exist far and wide in our surroundings. Studies have reported that both of DEHP and ELF-EMFs could promote cell proliferation which is related with adverse bioeffects. In this study, we investigated whether there is the combined effect between DEHP and 50-Hz magnetic fields (MFs) on cell proliferation in human amniotic (FL) cells. Results revealed that the low-concentration DEHP (1 μM) could promote FL cell proliferation, whereas the high-dose DEHP (100 μM) inhibited cell proliferation. When FL cells were treated jointly by a 50-Hz, 0.2-mT MF and 0.1 μM DEHP, the proliferation rate of cells was significantly higher than that of single factor exposure. Additionally, co-exposure to under-threshold MF and DEHP could cooperatively activate protein kinase B (Akt), sphingosine kinase 1 (SphK1) and extracellular signal regulated kinase (ERK) in a cascade manner, and finally mediate cell proliferation. Taken together, the findings of this study indicated that the co-exposure to under-threshold MF and DEHP could jointly promote cell proliferation through activating proliferation-related signal pathway, which warned us that it should be cautious about assessing the underlying health hazards of co-exposure to MFs and DEHP at under-threshold levels.

Breast cancer and occupational exposures: an integrative review of the literature

Occupational factors can lead to breast cancer, though the relationship between these variables is not well established. The objective of this study was to search the relevant literature for information on the association between breast cancer and exposure to occupational risk factors. For that purpose, electronic databases were searched using the following keywords: breast cancer and occupational exposures. A total of 40 articles published in the 10-year period from 2009 to 2019 were included in this review. Workers exposed to metals such as cadmium, chemical products, radiation and night work were more susceptible to breast cancer. The findings showed significant evidence to support an association between breast cancer and some chemical products, ionizing radiation and night work. However, most studies have difficulty establishing a causal relationship between these variables, pointing to the need for further investigation of these issues.

Occupational exposures and male breast cancer: A nested case-control study in the Nordic countries

BACKGROUND

Male breast cancer (MBC) is a rare and understudied disease. There is limited evidence on association between environmental and occupational agents and MBC. Some similarities in risk factors may be shared with female breast cancer. We evaluated solvents, metals, exhaust gases and other agents in relation to MBC within the large Nordic Occupational Cancer Study (NOCCA).

METHODS

The study included 1469 MBC cases and 7345 controls from Finland, Iceland and Sweden, matched for the date of birth, sex and country. Cases were identified through national cancer registries. Data on occupation and other demographic indicators were collected from census records and population registries. Overall, 24 occupational exposures were assessed. Exposure estimates were assigned by linking job titles to job-exposure matrices (NOCCA-JEM). Odds ratios (OR) and 95% confidence intervals (95% CI) were estimated by using conditional logistic regression models.

RESULTS

Significantly decreased overall OR was observed for physical workload (OR = 0.78, 95% CI 0.67-0.91). Protective effect of physical workload was stronger by increasing exposure level with significant dose-response relationship (p-trend<0.01). Non-significantly increased ORs were observed for trichloroethylene, iron, lead, chromium, welding fumes and wood dust, and decreased ORs for asbestos, silica dust and perchloroethylene. However, these results were not consistent across all analyses.

CONCLUSIONS

The current study showed 20-25% protective effect for physical workload at work, while no strong evidence for other agents was observed.

Evaluation in humans of ELF-EMF exposure on chromogranin A, a marker of neuroendocrine tumors and stress

Chromogranin A (CgA), which is a major protein in adrenal chromaffin cells and adrenergic neurons, is a clinically relevant endocrine and neuroendocrine tumor marker including pheochromocytomas, neuroblastomas, and related neurogenic tumors. In this study, we looked at the effect in humans of chronic daily exposure to a 50-Hz magnetic field. We examined in 15 men (38.0 ± 0.9 years) the effects of chronic daily exposure to a 50-Hz magnetic field for 1-20 yrs both at home and at work. EMDEX II dosimeters were used to record magnetic field all day long every 30 s. for 1 week. The weekly geometric mean of the individual exposures ranged from 0.1 to 2.6 μT. Blood samples were taken hourly between 20:00 h and 08:00 h. CgA patterns of exposed subjects were compared to age-matched controls. The results of exposed subjects were compared with those for 15 unexposed men who served as controls and whose individual exposure was ten times lower ranging from 0.004 to 0.092 μT. This work shows that in the control group the serum CgA levels exhibited a nighttime peak with a progressive decline of the serum concentrations and a nadir in the morning. Both the profile and the serum concentrations of CgA, a marker of neuroendocrine tumors and stress, did not appear to be impaired in the subjects chronically exposed over a long period (up to 20 yrs) to magnetic fields though a trend toward lower levels were found at the highest exposure (>0.3 μT). This does not rule out, however, that the potential deleterious risk of ELF-EMF on frail populations such as children and the elderly may be greater at low exposure and should hence be documented, at least for their residential exposure.

Extremely low frequency electromagnetic fields and cancer: How source of funding affects results

While there has been evidence indicating that excessive exposure to magnetic fields from 50 to 60 Hz electricity increases risk of cancer, many argue that the evidence is inconsistent and inconclusive. This is particularly the case regarding magnetic field exposure and childhood leukemia. A major goal of this study is to examine how source of funding influences the reported results and conclusions. Several meta-analyses dating from about 2000 all report significant associations between exposure and risk of leukemia. By examining subsequent reports on childhood leukemia it is clear that almost all government or independent studies find either a statistically significant association between magnetic field exposure and childhood leukemia, or an elevated risk of at least OR = 1.5, while almost all industry supported studies fail to find any significant or even suggestive association. A secondary goal of this report is to examine the level of evidence for exposure and elevated risk of various adult cancers. Based on pooled or meta-analyses as well as subsequent peer-reviewed studies there is strong evidence that excessive exposure to magnetic fields increases risk of adult leukemia, male and female breast cancer and brain cancer. There is less convincing but suggestive evidence for elevations in several other cancer types. There is less clear evidence for bias based on source of funding in the adult cancer studies. There is also some evidence that both paternal and maternal prenatal exposure to magnetic fields results in an increased risk of leukemia and brain cancer in offspring. When one allows for bias reflected in source of funding, the evidence that magnetic fields increase risk of cancer is neither inconsistent nor inconclusive. Furthermore adults are also at risk, not just children, and there is strong evidence for cancers in addition to leukemia, particularly brain and breast cancer.

Ursolic acid a promising candidate in the therapeutics of breast cancer: Current status and future implications

Breast cancer [BC] is the deadliest neoplasm in women globally and the second leading cause of cancer associated deaths. Current treatment methods include chemotherapy, hormonal therapy, radiation therapy and surgery. However, BC has shown resistance to these therapies and are often associated with side effects, multidrug resistance, recurrence are the major issues in BC treatment. Currently, dietary phytocompounds have emerged as beneficial agents for the prevention and treatment of cancer because of their safe and cost effective nature. Ursolic acid [UA] is widely spread in fruits and vegetables having the ability to inhibit BC proliferation, angiogenesis and metastasis, arrest cell cycle, induced apoptosis, scavenge free radicals and regulate several anti-apoptotic and pro-apoptotic proteins. UA has also shown potential anticancer, anti-inflammatory and antioxidant activities in several human BC cells. This review paper encompasses the role of UA against BC and their mechanism of action in vitro and in vivo studies.

Dietary Isoflavones and Breast Cancer Risk

Breast cancer is the deadliest neoplasm in women globally, resulting in a significant health burden. In many cases, breast cancer becomes resistant to chemotherapy, radiation, and hormonal therapies. It is believed that genetics is not the major cause of breast cancer. Other contributing risk factors include age at first childbirth, age at menarche, age at menopause, use of oral contraceptives, race and ethnicity, and diet. Diet has been shown to influence breast cancer incidence, recurrence, and prognosis. Soy isoflavones have long been a staple in Asian diets, and there appears to be an increase, albeit modest, compared to Asian populations, in soy consumption among Americans. Isoflavones are phytoestrogens that have antiestrogenic as well as estrogenic effects on breast cancer cells in culture, in animal models, and in clinical trials. This study will investigate anticancer and tumor promoting properties of dietary isoflavones and evaluate their effects on breast cancer development. Furthermore, this work seeks to elucidate the putative molecular pathways by which these phytochemicals modulate breast cancer risk by synergizing or antagonizing the estrogen receptor (ER) and in ER-independent signaling mechanisms.

Occupational exposure to magnetic fields and breast cancer among Canadian men

Occupational magnetic field (MF) exposure has been suggested as a risk factor for breast cancer in both men and women. Due to the rarity of this disease in men, most epidemiologic studies investigating this relationship have been limited by small sample sizes. Herein, associations of several measures of occupational MF exposure with breast cancer in men were investigated using data from the population-based case-control component of the Canadian National Enhanced Cancer Surveillance System. Lifetime job histories were provided by 115 cases and 570 controls. Average MF exposure of individual jobs was classified into three categories (<0.3, 0.3 to <0.6, or ≥0.6 μT) through expert blinded review of participant's lifetime occupational histories. The impact of highest average and cumulative MF exposure, as well as exposure duration and specific exposure-time windows, on cancer risk was examined using logistic regression. The proportion of cases (25%) with a highest average exposure of ≥0.3 μT was higher than among controls (22%). We found an elevated risk of breast cancer in men who were exposed to ≥0.6 μT (odds ratio [OR] = 1.80, 95% CI = 0.82-3.95) when compared to those with exposures <0.3 μT. Those exposed to occupational MF fields for at least 30 years had a nearly threefold increase in risk of breast cancer (OR = 2.77, 95% CI = 0.98-7.82) when compared to those with background levels of exposure. Findings for the other time-related MF variables were inconsistent. Our analysis, in one of the largest case-control studies of breast cancer in men conducted to date, provides limited support for the hypothesis that exposure to MF increases the risk breast cancer in men.