A systematic approach to evaluate plausible modes of actions for mouse lung tumors in mice exposed to 4-methylimidozole.

The National Toxicology Program (NTP) reported that chronic dietary exposure to 4-methylimidazole (4-MeI) increased the incidence of lung adenomas/carcinomas beyond the normally high spontaneous rate in B6C3F1 mice. To examine plausible modes of action (MoAs) for mouse lung tumors (MLTs) upon exposure to high levels of 4-MeI, and their relevance in assessing human risk, a systematic approach was used to identify and evaluate mechanistic data (in vitro and in vivo) in the primary and secondary literature, along with high-throughput screening assay data. Study quality, relevance, and activity of mechanistic data identified across the evidence-base were organized according to key characteristics of carcinogens (KCCs) to identify potential key events in known or novel MLT MoAs. Integration of these evidence streams provided confirmation that 4-MeI lacks genotoxic and cytotoxic activity with some evidence to support a lack of mitogenic activity. Further evaluation of contextual and chemical-specific characteristics of 4-MeI was consequently undertaken. Due to lack of genotoxicity, along with transcriptomic and histopathological lung changes up to 28 and 90 days of exposure, the collective evidence suggests MLTs observed following exposure to high levels of 4-MeI develop at a late stage in the mouse chronic bioassay, albeit the exact MoA remains unclear.

Repeated exposure to nanosecond high power pulsed microwaves increases cancer incidence in rat.

High-power microwaves are used to inhibit electronics of threatening military or civilian vehicles. This work aims to assess health hazards of high-power microwaves and helps to define hazard threshold levels of modulated radiofrequency exposures such as those emitted by the first generations of mobile phones. Rats were exposed to the highest possible field levels, under single acute or repetitive exposures for eight weeks. Intense microwave electric fields at 1 MV m-1 of nanoseconds duration were applied from two sources at different carrier frequencies of 10 and 3.7 GHz. The repetition rate was 100 pps, and the duration of train pulses lasted from 10 s to twice 8 min. The effects on the central nervous system were evaluated, by labelling brain inflammation marker GFAP and by performing different behavioural tests: rotarod, T-maze, beam-walking, open-field, and avoidance test. Long-time survival was measured in animals repeatedly exposed, and anatomopathological analysis was performed on animals sacrificed at two years of life or earlier in case of precocious death. Control groups were sham exposed. Few effects were observed on behaviour. With acute exposure, an avoidance reflex was shown at very high thermal level (22 W kg-1); GFAP was increased some days after exposure. Most importantly, with repeated exposures, survival time was 4-months shorter in the exposed group, with eleven animals exhibiting a large sub-cutaneous tumour, compared to two in the sham group. A residual X-ray exposure was also present in the beam (0.8 Gy), which is probably not a bias for the observed result. High power microwaves below thermal level in average, can increase cancer prevalence and decrease survival time in rats, without clear effects on behaviour. The parameters of this effect need to be further explored, and a more precise dosimetry to be performed.

Maternal Consumption of a Low-Isoflavone Soy Protein Isolate Diet Accelerates Chemically Induced Hepatic Carcinogenesis in Male Rat Offspring.

It has been reported that maternal nutrition determines the offspring's susceptibility to chronic diseases including cancer. Here, we investigated the effects of maternal diets differing in protein source on diethylnitrosamine (DEN)-induced hepatocarcinogenesis in adult rat offspring. Dams were fed a casein (CAS) diet or a low-isoflavone soy protein isolate (SPI) diet for two weeks before mating and throughout pregnancy and lactation. Offspring were weaned to and fed a chow diet throughout the study. From four weeks of age, hepatocellular carcinomas (HCC) were induced by intraperitoneal injection of DEN once a week for 14 weeks. The SPI/DEN group exhibited higher mortality rate, tumor multiplicity, and HCC incidence compared with the CAS/DEN group. Accordingly, altered cholesterol metabolism and increases in liver damage and angiogenesis were observed in the SPI/DEN group. The SPI/DEN group had a significant induction of the nuclear factor-κB-mediated anti-apoptotic pathway, as measured by increased phosphorylation of IκB kinase ß, which may lead to the survival of precancerous hepatocytes. In conclusion, maternal consumption of a low-isoflavone soy protein isolate diet accelerated chemically induced hepatocarcinogenesis in male rat offspring in the present study, suggesting that maternal dietary protein source may be involved in DEN-induced hepatocarcinogenesis in adult offspring.

Role of TNFα and leptin signaling in colon cancer incidence and tumor growth under obese phenotype.

Epidemiological studies over the last few decades have shown a strong influence of obesity on colon cancer risk and its progression. These studies have primarily focussed on the role of adipokines in driving cancer progression. We investigated the incidence of cancerous polyp formation and tumor progression in presence and absence of functional leptin along with exploring the role of tumor necrosis factor α (TNFα), under obese condition. By utilizing diet induced obese and genetically obese mice, carcinogen induced colon polyp formation was investigated. Experiments were performed using tumor tissues and cell lines to delineate the inter-relationship between leptin and TNFα. Data shown in this report indicates that in leptin knockdown obese mice, AOM/DSS induced polyps are smaller and lesser in numbers as compared to AOM/DSS induced polyps in diet induced obese mice. Further in vitro experiments suggest that abrogation of leptin associated pathways promote TNFα induced apoptosis. Mechanistically, we report that TNFα induces p53 independent cell death through up regulation of p53 upregulated modulator of apoptosis (PUMA). TNFα induced PUMA was inhibited upon pre- exposure of cells to leptin, prior to TNFα treatment. Collectively these results indicate that obesity due to leptin non-functionality facilitates TNFα induced colon cancer cell death.

Tetrahydrofuran-induced tumors in rodents are not relevant to humans: Quantitative weight of evidence analysis of mode of action information does not support classification of tetrahydrofuran as a possible human carcinogen.

Inhalation of tetrahydrofuran (THF) causes a marginal increase in the incidence of renal tumors in male rats and an increase in the incidence of liver tumors in female mice. Quantitative weight of evidence (QWoE) was applied to assess experimental support for biologically plausible modes of action (MoA) of tumor formation by THF and their human relevance. QWoE did not obtain support for a MoA to induce kidney tumors in male rats from THF exposure via α2u -globulin nephropathy, exacerbation of chronic progressive nephropathy (CPN), DNA-damage, or recurrent cytotoxicity but obtained moderate to good support for a constitutive androgen receptor (CAR)-mediated MoA for the induction of liver tumors in female mice. Tumors as a consequence of CAR-activation are not considered relevant to humans. Considering the previous conclusion that the increases in kidney tumors in male rats are unlikely related to THF-exposure and the support for a CAR-mediated MoA in mice obtained here, these tumors should not be used as a basis for THF cancer classification.

The Effect of Mouse Strain, Sex, and Carcinogen Dose on Toxicity and the Development of Lung Dysplasia and Squamous Cell Carcinomas in Mice.

In order to translate new treatments to the clinic, it is necessary to use animal models that closely recapitulate human disease. Lung cancer develops after extended exposure to carcinogens. It has one of the highest mutation rates of all cancer and is highly heterogenic. Topical treatment with N-nitrosotris-(2-chloroethyl)urea (NTCU) induces lung squamous cell carcinoma (SCC) with nonsynonymous mutation rates similar to those reported for human non-small cell lung cancer. However, NTCU induces lung cancer with variable efficacy and toxicity depending on the mouse strain. A detailed characterization of the NTCU model is needed. We have compared the effect of three different NTCU doses (20, 30, and 40 mmol/L) in female and male of NIH Swiss, Black Swiss, and FVB mice on tumor incidence, survival, and toxicity. The main findings in this study are (1) NIH Swiss mice present with a higher incidence of SCC and lower mortality compared with Black Swiss and FVB mice; (2) 30 mmol/L NTCU dose induces SCC at the same rate and incidence as the 40 mmol/L dose with lower mortality; (3) female mice present higher grade and incidence of preinvasive lesions and SCC compared with males; (4) NTCU-induced transformation is principally within the respiratory system; and (5) NTCU treatment does not affect the ability to elicit a specific adaptive immune response. This study provides a reference point for experimental designs to evaluate either preventive or therapeutic treatments for lung SCC, including immunotherapies, before initiating human clinical trials.

A Comparison of Spontaneous Tumors in Tg.rasH2 Mice in 26-week Carcinogenicity Studies Conducted at a Single Test Facility during 2004 to 2012 and 2013 to 2018.

This article presents the historical control data of spontaneous tumors in Tg.rasH2 published in 2013 (2004-2012) and compares and contrasts it to more recent data collected from 2013 to 2018, reporting differences in the average percentage incidences or incidence ranges as well as the incidence of new tumors. In 2013, we published a comprehensive review of spontaneous tumors in Tg.rasH2 mice used in 26-week carcinogenicity studies, which included data from control dose groups from 26 studies and a total of 710 mice per sex. The total database, now including the more recent data, has nearly doubled the number of animals, completing to date a total of 52 studies in males and 51 studies in females for a total of 1,615 male mice and 1,560 female mice, respectively. In this article, we compare the data collected from 2004 to 2012 against the data collected from 2013 to 2018 and the overall tumor incidence change.

Cutaneous wound healing through paradoxical MAPK activation by BRAF inhibitors.

BRAF inhibitors are highly effective therapies for the treatment of BRAF(V600)-mutated melanoma, with the main toxicity being a variety of hyperproliferative skin conditions due to paradoxical activation of the mitogen-activated protein kinase (MAPK) pathway in BRAF wild-type cells. Most of these hyperproliferative skin changes improve when a MEK inhibitor is co-administered, as it blocks paradoxical MAPK activation. Here we show how the BRAF inhibitor vemurafenib accelerates skin wound healing by inducing the proliferation and migration of human keratinocytes through extracellular signal-regulated kinase (ERK) phosphorylation and cell cycle progression. Topical treatment with vemurafenib in two wound-healing mice models accelerates cutaneous wound healing through paradoxical MAPK activation; addition of a mitogen-activated protein kinase kinase (MEK) inhibitor reverses the benefit of vemurafenib-accelerated wound healing. The same dosing regimen of topical BRAF inhibitor does not increase the incidence of cutaneous squamous cell carcinomas in mice. Therefore, topical BRAF inhibitors may have clinical applications in accelerating the healing of skin wounds.

Calidad de vida de pacientes con cáncer de próstata en tratamiento con bloqueo androgénico continuo vs intermitente. Estudio prospectivo mediante la aplicación del cuestionario CAVIPRES / Quality of life in patients diagnosed of prostate cancer treated with continuous androgen deprivation therapy vs. intermittent therapy. Prospective study through the application of the CAVIPRES questionnaire

Fundamento: El tratamiento con bloqueo androgénico intermitente (BAI) pretende mejorar la calidad de vida de los pacientes con cáncer de próstata con los mismos resultados oncológicos que el bloqueo androgénico continuo (BAC). El presente trabajo compara la calidad de vida mediante la aplicación del cuestionario CAVIPRES entre dos grupos de pacientes, uno tratado con BAC y otro con BAI. Material y métodos: Se realizó un estudio longitudinal de 24 meses de duración que incluyó 114 pacientes. Tras 6 meses se aleatorizaron a ambos grupos de tratamiento (49 pacientes a BAC y 51 a BAI), controlándose posteriormente a los 6, 12 y 18 meses de aleatorizarlos. Se comparó la puntuación de los bloques de ítems y la puntuación global del cuestionario CAVIPRES entre ambos grupos de tratamiento y se estudió su variación a lo largo del tiempo. Resultados: Los pacientes con BAI presentaron mejor calidad de vida global que los pacientes con BAC (p=0,002). De los 5 bloques en los que se divide el cuestionario, el grupo BAI presentó mejor puntuación que el BAC en "Aspectos psicológicos" (p=0,009) y "Apoyo social y pareja" (p=0,008). El BAI mejoró la calidad de vida global de los pacientes a los 18 meses respecto al momento de la aleatorización (p=0,000), y la puntuación de "Vida Sexual" (p=0,000) y "Apoyo social y pareja" (p=0,002). El BAC no mejoró ni la calidad de vida global ni la puntuación de los diferentes bloques a largo del estudio (p>0,05). Conclusión: El BAI mejora la calidad de vida global de los pacientes a los 18 meses de la suspensión del tratamiento (AU)

Background: Treatment with intermittent androgen deprvation (IAD) seeks to improve the quality of life of patients with prostate cancer, with the same oncologic results as continuous androgen deprivation (CAD). The aim of this paper is to compare, using the CAVIPRES questionnaire, the quality of life between two groups of patients, one treated with CAD and the other with IAD. Materials and methods: A longitudinal study was performed for 24 months involving 114 patients. After 6 months, patients were randomized to two treatment groups (49 patients in CAD and 51 patients in IAD), controlled at 6, 12 and 18 months from randomisation. The score of the items and the overall score of the CAVIPRES questionnaire between the two groups was compared and their variation over time was studied. Results: Patients with IAD had a better overall score than patients with CAD (p=0.002). Of the 5 blocks of items into which the questionnaire was divided, the IAD group had a better score than CAD in "Psychological aspects" (p=0.009) and "Social and partner support" (p=0.008). At 18 months, IAD improved the overall quality of life of patients relative to the time of randomization (p=0.000), as well as the score for "Sexual Life" (p=0.000) and "Social and partner support" (p=0.002). CAD did not improve overall quality of life or the score for the different blocks throughout the study (p>0.05). Conclusions: IAD improves overall quality of life of patients at 18 months of stopping treatment (AU)

Evaluation of carcinogenic potential of the herbicide glyphosate, drawing on tumor incidence data from fourteen chronic/carcinogenicity rodent studies.

Abstract Glyphosate, an herbicidal derivative of the amino acid glycine, was introduced to agriculture in the 1970s. Glyphosate targets and blocks a plant metabolic pathway not found in animals, the shikimate pathway, required for the synthesis of aromatic amino acids in plants. After almost forty years of commercial use, and multiple regulatory approvals including toxicology evaluations, literature reviews, and numerous human health risk assessments, the clear and consistent conclusions are that glyphosate is of low toxicological concern, and no concerns exist with respect to glyphosate use and cancer in humans. This manuscript discusses the basis for these conclusions. Most toxicological studies informing regulatory evaluations are of commercial interest and are proprietary in nature. Given the widespread attention to this molecule, the authors gained access to carcinogenicity data submitted to regulatory agencies and present overviews of each study, followed by a weight of evidence evaluation of tumor incidence data. Fourteen carcinogenicity studies (nine rat and five mouse) are evaluated for their individual reliability, and select neoplasms are identified for further evaluation across the data base. The original tumor incidence data from study reports are presented in the online data supplement. There was no evidence of a carcinogenic effect related to glyphosate treatment. The lack of a plausible mechanism, along with published epidemiology studies, which fail to demonstrate clear, statistically significant, unbiased and non-confounded associations between glyphosate and cancer of any single etiology, and a compelling weight of evidence, support the conclusion that glyphosate does not present concern with respect to carcinogenic potential in humans.

Long-term α1B-adrenergic receptor activation shortens lifespan, while α1A-adrenergic receptor stimulation prolongs lifespan in association with decreased cancer incidence.

The α1-adrenergic receptor (α1AR) subtypes, α1AAR and α1BAR, have differential effects in the heart and central nervous system. Long-term stimulation of the α1AAR subtype prolongs lifespan and provides cardio- and neuro-protective effects. We examined the lifespan of constitutively active mutant (CAM)-α1BAR mice and the incidence of cancer in mice expressing the CAM form of either the α1AAR (CAM-α1AAR mice) or α1BAR. CAM-α1BAR mice have a significantly shortened lifespan when compared with wild-type (WT) animals; however, the effect was sex dependent. Female CAM-α1BAR mice lived significantly shorter lives, while the median lifespan of male CAM-α1BAR mice was not different when compared with that of WT animals. There was no difference in the incidence of cancer in either sex of CAM-α1BAR mice. The incidence of cancer was significantly decreased in CAM-α1AAR mice when compared with that in WT, and no sex-dependent effects were observed. Further study is warranted on cancer incidence after activation of each α1AR subtype and the effect of sex on lifespan following activation of the α1BAR. The implications of a decrease in cancer incidence following long-term α1AAR stimulation could lead to improved treatments for cancer.

Spontaneous and experimental malignancies in non-human primates.

Contrary to earlier established opinion that tumors in monkeys are found rarely, now the large material confirms that monkey tumors are frequent phenomenon. Tumor incidence clearly increases with age. Frequencies of benign and malignant tumors of various locations and histogenesis are slightly different. Tumors of hematopoietic system are the most frequent. Sporadic cases and enzootic outbreaks of lymphomas are described for different kinds of monkeys, including apes, and probably are caused by viruses. Two viruses were isolated by us from sick monkeys - the retrovirus C-type STLV-1 and the herpes virus papio HVP. Inoculation of virus cultures into monkeys and rabbits induces neoplasms. Monkey neoplasms can be induced by exposure to various chemical agents, and by oncogenic and non-oncogenic viruses. There is no strict species specificity of tumor viruses. The role of polyoma viruses in neoplasms etiology is discussed.

Chemopreventive efficacy of Wedelia calendulaceae against 20-methylcholanthrene-induced carcinogenesis in mice.

Present study reports the chemopreventive effect of methanol extract of Wedelia calendulaceae (MEWC) against 20-methylcholanthrene (20-MC) induced carcinogenesis in Swiss albino mice. MEWC was administered orally at 250 and 500 mg/kg body weight for 90 consecutive days after 24h of single subcutaneous administration of 20-MC (200 µg) in mice and observed for 15 weeks to record tumor incidence (fibrosarcoma) and survival. After 15 weeks the mice were sacrificed for the estimation of hematological profiles and liver biochemical parameters viz. lipid peroxidation, reduced glutathione (GSH), glutathione-S-transferase (GST), superoxide dismutase (SOD) and catalase (CAT). MEWC treatment markedly reduced tumor incidence and prolonged life span of sarcoma bearing mice as compared to 20-MC control. Hematological profiles were significantly (p<0.001) restored to normal levels in MEWC treated mice. MEWC treatment significantly (p<0.001) modulated the aforesaid liver biochemical parameters as compared to 20-MC control. Therefore, W. calendulaceae possess remarkable chemopreventive efficacy in Swiss mice.

Quantitative comparison between in vivo DNA adduct formation from exposure to selected DNA-reactive carcinogens, natural background levels of DNA adduct formation and tumour incidence in rodent bioassays.

This study aimed at quantitatively comparing the occurrence/formation of DNA adducts with the carcinogenicity induced by a selection of DNA-reactive genotoxic carcinogens. Contrary to previous efforts, we used a very uniform set of data, limited to in vivo rat liver studies in order to investigate whether a correlation can be obtained, using a benchmark dose (BMD) approach. Dose-response data on both carcinogenicity and in vivo DNA adduct formation were available for six compounds, i.e. 2-acetylaminofluorene, aflatoxin B1, methyleugenol, safrole, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline and tamoxifen. BMD(10) values for liver carcinogenicity were calculated using the US Environmental Protection Agency BMD software. DNA adduct levels at this dose were extrapolated assuming linearity of the DNA adduct dose response. In addition, the levels of DNA adducts at the BMD(10) were compared to available data on endogenous background DNA damage in the target organ. Although for an individual carcinogen the tumour response increases when adduct levels increase, our results demonstrate that when comparing different carcinogens, no quantitative correlation exists between the level of DNA adduct formation and carcinogenicity. These data confirm that the quantity of DNA adducts formed by a DNA-reactive compound is not a carcinogenicity predictor but that other factors such as type of adduct and mutagenic potential may be equally relevant. Moreover, comparison to background DNA damage supports the notion that the mere occurrence of DNA adducts above or below the level of endogenous DNA damage is neither correlated to development of cancer. These data strongly emphasise the need to apply the mode of action framework to understand the contribution of other biological effect markers playing a role in carcinogenicity.

Profile of early occurring spontaneous tumors in Han Wistar rats.

It is sometimes difficult to assess the relevance of tumors that occur in treated animals in short-term studies. This report is intended to establish a general profile of tumor occurrence in young Han Wistar rats. Data were collected and evaluated from 29 rat carcinogenicity studies and from a few 2-, 4-, 13-, and 26-week studies conducted between 1995 and 2009 at Huntingdon Life Sciences, UK. The route of administration was dietary, oral gavage, or inhalation, and the analysis was confined to sporadic deaths (decedents) in carcinogenicity studies. In Han Wistar rats, the most common and earliest occurring tumor was malignant lymphoma in both sexes, the earliest being seen in the 16th and 26th week in males and females, respectively. The incidence of malignant lymphoma was slightly higher in males than in females. The second most common type of tumor was brain tumors in males and mammary tumors in females. Compared with Sprague-Dawley rats, where the most common early tumor was pituitary tumor in females, the most common early tumor in Han Wistar rats was malignant lymphoma in both sexes. These early tumor profiles are consistent with the lifetime tumor occurrence in these strains.

E2F1 plays a direct role in Rb stabilization and p53-independent tumor suppression.

To better understand the role of E2F1 in tumor formation, we analyzed spontaneous tumorigenesis in p53(-/-)E2F1(+/+) and p53(-/-)E2F1(-/-) mice. We show that the combined loss of p53 and E2F1 leads to an increased incidence of sarcomas and carcinomas compared to the loss of p53 alone. E2F1-deficient tumors show wide chromosomal variation, indicative of genomic instability. Consistent with this, p53(-/-)E2F1(-/-) primary fibroblasts have a reduced capacity to maintain genomic stability when exposed to S-phase inhibitors or genotoxic drugs. A major mechanism of E2F1's contribution to genomic integrity lies in mediating stabilization and engagement of the Rb protein.

Niacin supplementation decreases the incidence of alkylation-induced nonlymphocytic leukemia in Long-Evans rats.

Niacin deficiency impairs poly(ADP-ribose) formation and enhances ethylnitrosourea (ENU)-induced carcinogenesis. Previous experiments were compromised by rapid progression of cancer, and the current study was designed with half the number of ENU doses. Weanling male Long-Evans rats were fed niacin deficient (ND), pair-fed (PF) control (30 mg nicotinic acid/kg), or pharmacological niacin (NA; 4 g nicotinic acid/kg) diets. After 2 wk, rats were gavaged every other day with ENU [30 mg/kg body weight (bw)] or vehicle (6 doses). Four days after the last dose of ENU, all rats were switched to AIN-93M diet and mildly feed restricted to maintain a constant food intake per bw. Rats were monitored for termination criteria and assessed for cancer development. Total cancers developed more rapidly in rats on the ND diet compared to those receiving high dose supplements of NA (P = 0.02; Gehan's generalized Wilcoxon test). Importantly, all of these differences occurred in the leukemias, especially the nonlymphocytic leukemia fraction (P = 0.008; Gehan's generalized Wilcoxon test), with incidences of 36%, 17%, and 11% in ND, PF, and NA rats, respectively. Because nonlymphocytic leukemias represent the majority of secondary cancers, these data support the concept that niacin supplementation may help protect cancer patients from the deleterious side effects of chemotherapy.