Critical review of dose-response options for F344 rat mammary tumors for acrylamide - additional insights based on mode of action

Hyperprolactinaemia is common in Chinese premenopausal women with breast diseases

Purpose: Hyperprolactinaemia has been proposed to play a role in breast lesions pathophysiology. Thus far, controversial results have been reported for the relationship between hyperprolactinaemia and breast lesions. Moreover, the prevalence of hyperprolactinaemia in a population with breast lesions is scarcely reported. We aimed to investigate the prevalence of hyperprolactinaemia in Chinese premenopausal women with breast diseases, and explore the associations between hyperprolactinaemia with different clinical characteristics. Methods: This was a retrospective cross-sectional study performed in the department of breast surgery of Qilu hospital of Shandong University. Overall, 1,461 female patients who underwent the serum prolactin (PRL) level assay before breast surgery from January 2019 to December 2020 were included. Patients were divided into two groups: before and after menopause. Data were analyzed using SPSS 18.0 software. Results: The results showed an elevated PRL level in 376 of the 1,461 female patients with breast lesions (25.74%). Furthermore, the proportion of hyperprolactinemia among premenopausal patients with breast disease (35.75%, 340/951) was significantly higher than among postmenopausal patients with breast disease (7.06%, 36/510). In premenopausal patients, the proportion of patients with hyperprolactinaemia and the mean serum PRL level were significantly higher in those diagnosed with fibroepithelial tumours (FETs) and in younger patients (aged < 35 years) than in those with non-neoplastic lesions and in those aged ≥ 35 years (both p < 0.05). Especially, the prolactin level exhibited steady ascending tendency for positive correlation with FET. Conclusion: Hyperprolactinaemia is prevalent in Chinese premenopausal patients with breast diseases, especially in those with FETs, which implies a potential association, to some extent, between the PRL levels in various breast diseases.

Dietary exposure to acrylamide and breast cancer risk: results from the NutriNet-Santé cohort

BACKGROUND

Acrylamide is classified as a probable human carcinogen by the International Agency for Research on Cancer but epidemiologic evidence on the carcinogenicity of acrylamide from dietary sources is limited.

OBJECTIVES

This study aimed to investigate the associations between dietary acrylamide and breast cancer risk in the NutriNet-Santé cohort, accounting for menopausal and hormone receptor status.

METHODS

This prospective cohort study included 80,597 French females (mean ± SD age at baseline: 40.8 ± 14 y) during a mean ± SD follow-up of 8.8 ± 2.3 y. Acrylamide intake was evaluated using repeated 24-h dietary records (n ± SD = 5.5 ± 3.0), linked to a comprehensive food composition database. Associations between acrylamide intake and breast cancer risk (overall, premenopausal, and postmenopausal) were assessed by Cox hazard models adjusted for known risk factors (sociodemographic, anthropometric, lifestyle, medical history, and nutritional factors).

RESULTS

The mean ± SD dietary acrylamide intake was 30.1 ± 21.9 µg/d (main contributors: coffee, potato fries and chips, pastries, cakes, bread). During follow-up, 1016 first incident breast cancer cases were diagnosed (431 premenopausal, 585 postmenopausal). A borderline significant positive association was observed between dietary acrylamide exposure and breast cancer risk overall (HR for quartile 4 compared with 1: 1.21; 95% CI: 1.00, 1.47) and a positive association was observed with premenopausal cancer (HRQ4vs.Q1: 1.40; 95% CI: 1.04, 1.88). Restricted cubic spline analyses suggested evidence for nonlinearity of these associations, with higher HRs for intermediate (quartile 2) and high (quartile 4) exposures. Receptor-specific analyses revealed positive associations with estrogen receptor-positive breast cancer (total and premenopausal). Acrylamide intake was not associated with postmenopausal breast cancer.

CONCLUSIONS

Results from this large prospective cohort study suggest a positive association between dietary acrylamide and breast cancer risk, especially in premenopausal females, and provide new insights that support continued mitigation strategies to reduce the content of acrylamide in food.This trial was registered at clinicaltrials.gov as NCT03335644.

Acrylamide impairs ovarian function by promoting apoptosis and affecting reproductive hormone release, steroidogenesis and autophagy-related genes: An in vivo study

Acrylamide (ACR) toxicity is quite common due to its widespread use in industry and due to the Maillard browning reaction that occurs in foods containing high concentrations of hydrocarbons subjected to high temperatures. This study aimed to elucidate the female reproductive toxicity of ACR in vivo. Fifty-day-old Wistar-Albino female rats were treated with different dosages of ACR (2.5, 10, and 50 mg/kg/day). After treatment, the animals were sacrificed, and serum and ovary samples were collected for histological examination, hormone analysis, TUNEL analysis, and RT-PCR studies. We found that ACR acts by significantly reducing ovarian weight and serum progesterone and estradiol concentrations. In addition, ACR treatment led to pyknotic, heterochromatic characteristics and nuclear fragmentation, as evidenced by hematoxylin staining. The TUNEL assay revealed that granulosa cells were affected after the oral administration of ACR, leading to the apoptosis of follicles at different stages of growth. Compared with the control condition, high doses of ACR (50 mg/kg/day) significantly induced the overexpression of INSL3, CYP17a, IGF1, ESR1, ESR2, ATG5, ATG12 and LC3 in the ovary. Moreover, LC3 mRNA levels significantly increased with increasing doses of ACR (2.5, 10 and 50 mg/kg/day), suggesting that ACR treatment induced autophagy. In conclusion, ACR induced ovarian dysfunction by affecting steroid hormone release, increasing apoptosis and mRNA levels of autophagy-related genes. The eventual correlation between apoptotic granulosa cell death and autophagy needs to be further explored.

Derivation of a No significant risk level (NSRL) for acrylamide

Acrylamide is included on the State of California's Proposition 65 list as a carcinogen. Acrylamide is found in cigarette smoke and in many types of foods, including breads, cereals, coffee, cookies, French fries, and potato chips. In 1990, California's Office of Environmental Health Hazard Assessment (OEHHA) established a no significant risk level (NSRL) of 0.2 μg/day for acrylamide. Since then, multiple cancer studies have been published. In this report, we developed an updated NSRL for acrylamide. Using benchmark dose modeling and a weight-of-evidence, non-threshold approach to identify the most sensitive species, cancer slope factors (CSFs) were derived based on combined incidences of statistically significant neoplastic lesions in the Harderian gland, lung, and stomach in male mice. We then used a toxicokinetic (TK)-based scaling approach to convert the animal CSF to a human equivalent CSF, which served as the basis for the NSRL of 1.1 μg/day at the cancer risk level of 1 in 100,000. This NSRL can be used in quantitative exposure assessments to assess compliance with Proposition 65 to ascertain either the need for or exemption from the Proposition 65 labeling requirement and drinking water discharge prohibition.

Sensitivity of glutathione S-transferases to high doses of acrylamide in albino wistar rats: Affinity purification, biochemical characterization and expression analysis

The main objectives of this study were to purify the glutathione S-transfereses (GSTs) and assess the effect of high doses of acrylamide (ACR) on male albino Wistar rat liver, kidney, testis and bran GST activities, and expression analysis of GST. ACR (50 mg/300 ml) was ingested for 40 days (20 doses) in drinking water on alternative days, on 40 day post ingestion the control and treated tissues were collected for GST purification by affinity column and biochemical characterization of GSTs by substrate specificities, and GST expression by immuno dot blots. In the analysis of the purified GSTs, we observed that liver GSTs were resolved in to three bands known as Yc, Yb and Ya; kidney GSTs were resolved in to two bands known as Yc and Ya; testis and brain GSTs were resolved as four bands known as Yc, Yb, Yβ and Yδ on 12.5% sodium dodecyl sulfate polyacrylamide gel (SDS PAGE). In the analysis of biochemical characterization, we observed a significant decrease (p < 0.05) in the specific activities of liver GST isoforms with the substrates 1-chloro 2,4-dinitrobenzene (CDNB), bromosulfophthalein (BSP), p-nitrophenyl acetate (pNPA), p-nitrobenzyl chloride (pNBC) and cumene hydroperoxide (CHP), but showed no activity with ethacrynic acid (ECA) and significant decrease (p < 0.05) in the specific activities of kidney GST isoforms with the substrates CDNB, pNPA, pNBC and CHP, but showed no activity with BSP and ECA, and a significant decrease (p < 0.05) in the specific activities of testis and brain GST isoforms with the substrates CDNB, BSP, pNPA, pNBC, ECA and CHP. In the analysis of immuno dot blots, we observed a decreased expression of liver, kidney, testis and brain GSTs. Through the affinity purification and biochemical characterization, we observed a tissue specific distribution of GSTs that is liver GSTs possess Yc, Yb and Ya sub units known as alpha (α) and mu (μ) class GSTs; kidney GSTs possess Yc and Ya sub units known as (α) alpha class GST; testis and brain GSTs possess Yc, Yb, Yβ and Yδ sub units known as alpha (α), mu (μ) and pi (π) class GSTs. Purification studies, biochemical characterization and immuno dot blot analysis were revealed the GSTs were sensitive to high doses of ACR and the high level exposure to ACR cause the damage of detoxification function of GST due to decreased expression and hence lead to cellular dysfunction of vital organs.

Glutathione S-transferase is a good biomarker in acrylamide induced neurotoxicity and genotoxicity

Glutathione S-transferases (GSTs) are major defence enzymes of the antioxidant enzymatic system. Cytosolic GSTs are more involved in the detoxification than mitochondrial and microsomal GSTs. GSTs are localized in the cerebellum and hippocampus of the rat brain. Acrylamide (AC) is a well assessed neurotoxin of both animals and humans and it produces skeletal muscle weakness and ataxia. AC is extensively used in several industries such as cosmetic, paper, textile, in ore processing, as soil conditioners, flocculants for waste water treatment and it is present in daily consumed food products, like potato chips, French fries, bread, breakfast cereals and beverages like coffee; it is detected on tobacco smoking. GST acts as a biomarker in response to acrylamide. AC can interact with DNA and therefore generate mutations. In rats, low level expression of glutathione S-trasferase (GST) decreases both memory and life span. The major aim of this review is to provide better information on the antioxidant role of GST against AC induced neurotoxicity and genotoxicity.

Interaction between dietary acrylamide intake and genetic variants for estrogen receptor-positive breast cancer risk

Purpose

The association between dietary acrylamide intake and estrogen receptor-positive (ER+) breast cancer risk in epidemiological studies is inconsistent. By analyzing gene-acrylamide interactions for ER+ breast cancer risk, we aimed to clarify the role of acrylamide intake in ER+ breast cancer etiology.

Methods

The prospective Netherlands Cohort Study on diet and cancer includes 62,573 women, aged 55–69 years. At baseline, a random subcohort of 2589 women was sampled from the total cohort for a case–cohort analysis approach. Dietary acrylamide intake of subcohort members (n = 1449) and ER+ breast cancer cases (n = 844) was assessed with a food frequency questionnaire. We genotyped single nucleotide polymorphisms (SNPs) in genes in acrylamide metabolism, sex steroid systems, oxidative stress and DNA repair. Multiplicative interaction between acrylamide intake and SNPs was assessed with Cox proportional hazards analysis, based on 20.3 years of follow-up.

Results

Unexpectedly, there was a statistically non-significant inverse association between acrylamide and ER+ breast cancer risk among all women but with no clear dose–response relationship, and no association among never smokers. Among the results for 57 SNPs and 2 gene deletions, rs1056827 in CYP1B1, rs2959008 and rs7173655 in CYP11A1, the GSTT1 gene deletion, and rs1052133 in hOGG1 showed a statistically significant interaction with acrylamide intake for ER+ breast cancer risk.

Conclusions

This study did not provide evidence for a positive association between acrylamide intake and ER+ breast cancer risk. If anything, acrylamide was associated with a decreased ER+ breast cancer risk. The interaction with SNPs in CYP1B1 and CYP11A1 suggests that acrylamide may influence ER+ breast cancer risk through sex hormone pathways.

Electronic supplementary material

The online version of this article (10.1007/s00394-018-1619-z) contains supplementary material, which is available to authorized users.