Breast Cancer In Sprague-Dawley Rats Research Articles

Zingiberene exerts chemopreventive activity against 7,12-dimethylbenz(a)anthracene-induced breast cancer in Sprague-Dawley rats.

Breast cancer is the primary cause of cancer-related death in females, wherein increased mortality of breast cancer patients is recorded worldwide. Zingiberene is a monocyclic sesquiterpene from the ginger plant and has many pharmacological benefits. In this exploration, we assessed the anticancer actions of Zingiberene against the 7,12-dimethylbenz(a)anthracene (DMBA)-stimulated mammary carcinogenesis in rats and MDA-MB-231 cells. Breast cancer was induced in the Female Sprague-Dawley rats through the 25 mg/kg of DMBA in 0.5 ml of corn oil and then treated with 20 and 40 mg/kg of Zingiberene, respectively. The body weight of animals and tumor volume was measured. Hematological parameters, transaminases, lipid profile, lipid peroxidation, and antioxidants status were scrutinized using standard techniques. The estrogen receptor-α and inflammatory markers were inspected by using respective assay kits. Histological damage scores were determined. In vitro experiments were conducted to scrutinize Zingiberene's effect on cell viability and apoptotic cell death in MDA-MB-231 cells. Zingiberene substantially modulated the DMBA-stimulated physiological and hematological changes and decreased the transaminases, and lipid peroxidation in the DMBA-stimulated animals. Zingiberene also elevated the antioxidant level and suppressed the inflammatory markers. Histological study revealed the protective effects of Zingiberene. The viability of MDA-MB-231 cells was noticeably diminished by the Zingiberene, thus inducing apoptotic cell death. Overall, our findings reliably proved the anticancer potential of Zingiberene against the DMBA-stimulated mammary tumorigenesis, and it could be a promising chemotherapeutic agent.

Herniarin, a natural coumarin, inhibits mammary carcinogenesis by modulating liver X receptor-α/β-PI3K-Akt-Maf1 Pathway in sprague-dawley rats

Background: The massive tumor burden following breast cancer initiation requires a constant supply of energy achieved by modification of different metabolic pathways. Enhanced lipid synthesis associated with glucose metabolism modification triggered by a battery of signaling events promotes unregulated cell division and growth. Coumarins with their diversified bioactivity are also recognized for their therapeutic efficacy in breast cancer. Objectives: Thus, this study was performed to assess the chemotherapeutic potential of herniarin (HER), a 7-methoxycoumarin derivative against polycyclic aromatic hydrocarbon-induced mammary cancer. Materials and Methods: In silico molecular docking was carried out to identify the interactions of HER with LXR α and β, 3-hydroxy-3-methylglutaryl-coenzyme A reductase (HMGCoAR), PI3K, and Akt followed by in vitro evaluation of HMGCoAR inhibitory potential of HER. Detailed in vivo studies was then performed in 7,12-dimethylbenz(a) anthracene-induced breast cancer model in Sprague-Dawley (SD) rats using HER at doses 20 mg/kg, b. w. and 40 mg/kg, b. w. along with molecular-level analysis (messenger RNA and proteins) by real-time quantitative polymerase chain reaction, Western blot, and enzyme-linked immunosorbent assay. Results: The docking studies revealed a significant binding affinity of HER to the aforesaid receptors and its HMGCoAR inhibitory potential (IC50 =103.1 nM) validated the docking studies. HER successfully re-established the lipid and lipoprotein levels along with the activities of lipid-metabolizing enzymes and glycolytic enzymes that were altered following cancer induction. The molecular biology evaluations reflected the efficiency of HER as it evidently alleviated the overexpression of HMGCOAR, PI3K, and Akt along with the lipogenic genes fatty acid synthase and acetyl-CoA carboxylase 1 in the carcinoma-developed animals by upregulating LXR (α and β) and Maf1. Conclusion: The bioactive moiety HER efficiently controlled alterations in metabolic pathways, thus balancing energy consumption, attenuating tumor progression through LXR/PI3K/Akt/Maf1 axis in breast cancer in SD rats.

Taxifolin Inhibits 7,12-Dimethylbenz(a)anthracene-induced Breast Carcinogenesis by Regulating AhR/CYP1A1 Signaling Pathway.

Background:Breast cancer (BC), because of its invasive characteristics, is one of the most common and deadliest cancers among the female population around the world. Research has demonstrated that AhR signaling also plays a vital role in BC initiation and development as well. Therefore, blocking this pathway to natural interferences paves a new channel for the prevention of BC. Several natural compounds such as flavonoids possess the anticancer activities against different cancers.Objective:The present study has been designed to estimate the chemotherapeutic potential of taxifolin (TAX) against 7,12-dimethylbenz(a)anthracene (DMBA)-induced mammary carcinoma in Sprague-Dawley rats.Materials and Methods:Initially, the molecular docking analysis of AhR and cytochrome P450s (CYPs) (CYP1A1 and CYP1B1) was performed using MAESTRO tool, in an attempt to rationalize the activity of TAX, based on their CYP1-binding potential. The in vitro CYP1A1 activity was determined by luciferase assay with CYP1A1 substrate luciferin CEE. The in vivo analysis was performed by administrating TAX at 10, 20, 40 mg/kg BW for 28 days intragastrically in DMBA induced (25 mg/animal dose) at 55 days of age Sprague-Dawley (SD) rats. BC initiates after 90 days of tumor induction phase. The molecular mechanism of TAX on Ahr and CYPs was also examined through the mRNA and protein expressions using reverse transcription-quantitative polymerase chain reaction and Western blotting analysis.Results:Furthermore, TAX altered the energy regulation on DMBA-induced BC in SD rats by considerably restoring the cancer-induced modulations in tumor growth. Our results showed that TAX reduced the expressions of CYP1A1 and CYP1B1 in DMBA-induced mammary carcinoma by downregulating the AhR signaling pathway.Conclusion:This study revealed that TAX might be able to act as a chemotherapeutic agent against CYP1A1- and CYP1B1-mediated cancer and the inhibition of the DMBA-induced mammary carcinogenesis in a rat model.Abbreviations used: CYPs: Cytochrome P450s; PAH: polycyclic aromatic hydrocarbons; HRP- Horseradish peroxidase; BSA: Bovine serum albumin; DTTP: Deoxythymidine Triphosphate (nucleotide); RT-qPCR: Real Time quantitative polymerase chain reaction; CADD: Computer Aided Drug Drafting.

Abstract 837: Reproducibility of efficacy results for chemopreventive agents in the methylnitrosourea-induced rat mammary cancer model

Abstract Perhaps the greatest question in biological science is: Can results be reproduced? This problem is of particular concern for a group whose primary mission is to screen for potentially effective agents and rank results by activity. The reproducibility of testing specific agents for chemopreventive activity, testing the same agent in various protocols, and testing multiple agents of a given mechanistic class in the MNU-induced model of ER+ breast cancer in Sprague-Dawley rats is presented. The model employs female virgin Sprague-Dawley rats on a standard 4% Teklad diet which develop ER+ mammary cancers (adenocarcinomas) following MNU injection at 50 days of age (DOA). Preventive agents were given by gavage or diet starting at 55 DOA, and animals monitored for tumor development until approximately 170 DOA. Seven agents which we had previously studied and which were strongly positive [tamoxifen, vorozole (an aromatase inhibitor), Targretin, gefitinib] or strongly negative (naproxen, Lipitor, metformin) were examined in the assays presented. These study results confirmed our previous data. We next tested these same agents in animals given a Western diet (high fat, low calcium) and again obtained the same results. We had thought that the altered physiology and potentially altered pharmacokinetics of rats on a Western diet might alter the observed chemopreventive efficacy. These studies show that the direct repetition of clearly positive and negative agents can be achieved and, in fact, repeated with a significant variation in diet. Importantly, in terms of reproducibility, we find that multiple agents of the same mechanistic class give similar results. Thus, various SERMs (tamoxifen, toremifene, Arzoxifene), RXR agonists (targretin, UAB-30, 4Me-UAB-30), EGFR inhibitors (gefitinib, Erlotinib, lapatinib) are all highly positive (70-95% reduction of cancer multiplicity). In contrast, the negative classes COX inhibitors (naproxen, sulindac, aspirin) or statins (atorvastatin or simvastatin) have been consistently negative (<20% reduction). Therefore, reproducibility of efficacy results appears to be quite solid in our chemoprevention agent development program for rat mammary cancer testing, and we can, with significant certainty, trust our results. Citation Format: Vernon E. Steele, Ronald A. Lubet, Clinton J. Grubbs. Reproducibility of efficacy results for chemopreventive agents in the methylnitrosourea-induced rat mammary cancer model. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 837.

Evaluation of oral bioavailability and anticancer potential of raloxifene solid lipid nanoparticles.

The objective of the present investigation was formulation of raloxifene loaded solid lipid nanoparticles (R-SLN) for oral administration and evaluation of its anticancer potential in 7,12- dimethylbenzanthracene (DMBA)-induced breast cancer in Sprague-Dawley rats. Optimized R-SLN formulation prepared by modified micro-emulsion method resulted in R-SLN of 288.0±28.5 nm size and 95.56% entrapment efficiency. R-SLN exhibited in vitro prolonged release of raloxifene for 72 h in phosphate buffered saline. R-SLN was stable in simulated gastro-intestinal (GIT) fluids consisting of pH 1.2, pH 7.4, simulated gastric fluid and simulated intestinal fluid. A two-fold increase was observed in raloxifene oral bioavailability from R-SLN. R-SLN exhibited enhanced efficacy and chemopreventive activity over pure raloxifene as indicated by evaluation of tumor burden (P < 0.001) and tumor incidence (P < 0.001). The results indicate the potential of raloxifene solid lipid nanoparticles in optimizing chemoprevention of breast cancer by R-SLN.

Evaluation of bioavailability, efficacy, and safety profile of doxorubicin-loaded solid lipid nanoparticles

We investigated the bioavailability, efficacy, and toxicity of doxorubicin-loaded solid lipid nanoparticles (DOX-SLNs) prepared by a simple modified double-emulsification method. A 3-factor, 3-level Box–Behnken statistical design was adopted in the optimization of DOX-SLN formulation considering dependent factors particle size and entrapment efficiency. Optimized SLN formulation composed of lipid (2 %) consisting of soya lecithin and Precirol ATO 5 (1:3) with Pluronic F68 (0.3 %) resulted in 217.36 ± 3.31 nm particle size and 59.45 ± 1.75 % entrapment efficiency. DOX-SLN exhibited significant enhancement (p < 0.05) in bioavailability as compared with free DOX in Sprague–Dawley (SD) rats. DOX-SLN exhibited higher peak plasma concentration (6.761 ± 0.08 vs. 2.412 ± 0.04 μg/ml), increased AUC (61.368 ± 3.54 vs. 5.812 ± 0.49 μg/ml h), decreased clearance (36 ± 0.01 vs. 619 ± 0.005 mL/h kg), and volume of distribution (733 ± 0.092 vs. 2,064 ± 0.061 mL/kg) when compared to free DOX. The collective results of cardiac and kidney enzyme assay, antioxidant enzyme levels, hematological parameters, effect on body weight and tumor volume, tumor necrosis factor-α level, histopathological examination, and survival analysis confirmed the improved efficacy and safety profile of DOX-SLN in 7,12-dimethyl benzanthracene-induced breast cancer in SD rats.

Effects of 50- or 60-hertz, 100 microT magnetic field exposure in the DMBA mammary cancer model in Sprague-Dawley rats: possible explanations for different results from two laboratories.

In line with the possible relationship between electric power and breast cancer risk and the underlying melatonin hypothesis, 50-Hz magnetic field (MF) exposure at microtesla flux densities for either 13 or 27 weeks significantly increased the development and growth of mammary tumors in a series of experiments from Löscher's group in Germany. Löscher's group used the 7,12-dimethylbenz[a]anthracene (DMBA) model of breast cancer in Sprague-Dawley rats. The finding could not be replicated when a similar experimental protocol was used in a study conducted by Battelle in the United States. In the present paper, investigators from the two groups discuss differences between their studies that might explain the apparent discrepancies between the results. These differences include the use of different substrains of Sprague-Dawley rats (the U.S. rats were more susceptible to DMBA than the European rats), different sources for diet and DMBA, differences in environmental conditions, and differences in MF exposure metrics. Furthermore, the effects of MF exposure reported by Löscher's group, albeit significant, were weak. We also discuss the general problem of replicating such weak effects.

Exposure of Female Rats to a 100-μT 50 Hz Magnetic Field Does Not Induce Consistent Changes in Nocturnal Levels of Melatonin

The hypothesis whereby alternating (50 or 60 Hz) magnetic fields such as those produced by electric power reduce the nocturnal production of melatonin in the pineal gland and thereby indirectly enhance development and growth of breast cancer has attracted a great deal of interest. In view of the potential importance of this hypothesis that there is a link between electric power and breast cancer, which is also known as the "melatonin hypothesis", we undertook various experiments in female Sprague-Dawley rats to evaluate whether 100-microT 50 Hz magnetic-field exposure, i.e. a flux density shown recently to exert a tumor (co)promoting effect in the 7,12-dimethylbenz[a]anthracene (DMBA) model of breast cancer in Sprague-Dawley rats, consistently reduces melatonin levels and, if not, which factors may be involved in the inconsistent effects of magnetic-field exposure on production of melatonin. Long-term exposure of female Sprague-Dawley rats to magnetic fields for 13 weeks did not alter the nocturnal levels of melatonin in the pineal gland or serum (determined 5 h after the onset of darkness) significantly, irrespective of whether rats were treated with DMBA or not. In one experiment, when blood was sampled 3, 5 and 6 h after the onset of darkness after 2 weeks of magnetic-field or sham exposure, a significant decrease in melatonin was seen in magnetic-field-exposed rats at 6 h. However, the results could not be reproduced in two subsequent experiments in other groups of rats. Shorter (1 day, 1 week) or longer (4, 8, 13 weeks) exposure periods also did not result in any significant effects of the magnetic field on melatonin levels when blood sampling was performed either 5 or 6 h after onset of the dark phase. Various potential sources of variation in melatonin levels or in magnetic-field effects on melatonin levels were evaluated, but the reason(s) for the inconsistent effect of magnetic-field exposure remains unclear. Thus the present study failed to demonstrate a consistent effect of 100-microT 50 Hz magnetic-field exposure on melatonin levels in Sprague-Dawley rats.