ACI Rats Research Articles

MicroRNAs in the development and neoplasia of the mammary gland.

Study on the role of microRNAs (miRs) as regulators of gene expression through posttranscriptional gene silencing is currently gaining much interest,due to their wide involvement in different physiological processes. Understanding mammary gland development, lactation, and neoplasia in relation to miRs is essential. miR expression profiling of the mammary gland from different species in various developmental stages shows their role as critical regulators of development. miRs such as miR-126, miR-150, and miR-145 have been shown to be involved in lipid metabolism during lactation. In addition, lactogenic hormones influence miR expression as evidenced by overexpression of miR-148a in cow mammary epithelial cells, leading to enhanced lactation. Similarly, the miR-29 family modulates lactation-related gene expression by regulating DNA methylation of their promoters. Besides their role in development, lactation and involution, miRs are responsible for breast cancer development. Perturbed estrogen (E2) signaling is one of the major causes of breast cancer. Increased E2 levels cause altered expression of ERα, and ERα-miR cross-talk promotes tumour progression. miRs, such as miR-206, miR-34a, miR-17-5p, and miR-125 a/b are found to be tumour suppressors; whereas miR-21, miR-10B, and miR-155 are oncogenes.Studies using an ACI rat model showed similar findings of miR dysregulation due to excess E2, and a natural phenol antioxidant ellagic acid showed therapeutic properties by reversing the miR dysregulation. This review focuses on the recent findings concerning the role of miRs in developmental stages of the mammary gland (mainly lactation and involution stages) and their involvement in breast cancer progression. Further studies in this area will help us understand the molecular details of mammary gland biology,as well as miRs that could be therapeutic targets of breast cancer.

Study on the effect of chemoembolization combined with microwave ablation for the treatment of hepatocellular carcinoma in rats.

We aimed to evaluate the combining effects of transarterial chemoembolization (TACE) and open local thermal microwave ablation in a hepatocellular carcinoma animal model. Tumor cubes were implanted into the liver of 30 male inbred ACI rats. Groups of 10 animals were treated at 13 days (TACE or microwave ablation) and 16 days (microwave ablation) postimplantation with combined therapy of TACE (0.1 mg mitomycin C; 0.1 mg iodized oil; 5.0 mg degradable starch microspheres) and microwave ablation (2450 Mhz; 45 s; 35 W) (study group A), TACE alone (control group B), or microwave ablation alone (control group C). At day 12 and day 25 tumor size was measured via magnetic resonance imaging and the relative growth ratio was calculated. Hepatic specimens were immunohistochemically examined for the expression of vascular endothelial growth factor (VEGF). Mean growth rates were 1.34±0.19 in group A, 3.19±0.13 in group B, and 4.18±0.19 in group C. Compared with control groups B and C, tumor growth rate in group A was significantly inhibited (P < 0.01). The VEGF-antibody reaction in peritumoral tissue (staining intensity at portal triad, percent antibody reaction and staining intensity at central vein) was significantly lower in group A compared with group B (P < 0.01). No significant difference between group A and group C could be observed. This investigation shows improved results of TACE followed by microwave ablation as treatment of hepatocellular carcinoma in a rat model, compared with single therapy regimen regarding the inhibition of growth rate and reduction of VEGF-level in peritumoral tissue.

Immunosuppressive effects of mesenchymal stem cells on tacrolimus therapy in rat heart transplant model

Introduction: Mesenchymal stem cells (MSCs) are used in various clinical settings for effective cell therapy by taking advantage of their immunomodulatory, regenerative, and anti-inflammatory properties. We previously investigated the effects of the regenerative and anti-inflammatory properties of MSCs for consideration of their clinical application in organ transplantation. Since immunosuppressant agents are administered in nearly all clinical cases of organ transplantation, clarification of the immunological interaction between MSCs and the calcineurin inhibitor tacrolimus (TAC) is needed.Aim: Due to potential use of MSCs in organ transplantation, we assessed immunological interactions between TAC and MSCs in vivo.Methods: Adipose tissue-derived MSCs (AT-MSCs) were obtained from wild-type Lewis rats. We then used a rat heart transplantation model to observe the immunosuppressive effects of AT-MSCs, TAC, and those in combination. Following allogeneic heterotopic heart transplantation from ACI rats to Lewis rats, graft survival was assessed in groups treated with AT-MSCs, TAC, both, or neither.Results: Median survival of the allograft was 14.5 days in the TAC-alone group and 11 days in the MSC+TAC group. Although the difference between those groups was not significant, the survival periods of both were significantly longer as compared to that of the control (median survival =5 days, P<0.05) and MSC-alone (median survival =5 days, P<0.05) groups.Conclusions: Administration of AT-MSCs did not decrease the beneficial immunosuppressive effect of TAC on heart graft survival. TAC appears to be compatible and effective for clinical use as an immunosuppressant with AT-MSCs.

Fetal mesenchymal stem cells ameliorate acute lung injury in a rat cardiopulmonary bypass model

BackgroundSystemic inflammation after prolonged cardiopulmonary bypass (CPB) can cause serious multiorgan system dysfunction. Mesenchymal stem cells (MSCs) are reported to reduce inflammation and attenuate immune response. We have focused on fetal membrane (FM) as a source to provide a large number of MSCs (FM-MSCs). Allogeneic administration of FM-MSCs has been reported to mitigate autoimmune myocarditis or glomerulonephritis. The aim of this study was to investigate whether allogeneic FM-MSCs attenuate systemic inflammatory responses and lung injury in a rat CPB model. MethodsMale Lewis rats (major histocompatibility complex haplotype: RT-1l) were divided randomly into 3 groups (n = 7 each): cannulation alone (sham group), CPB alone (control group), and CPB + MSC (MSC group). An experimental rat CPB model was established, and CPB was maintained for 30 minutes. In the MSC group, MSCs (1 × 106 cells) derived from the FM of ACI rats with a different major histocompatibility complex haplotype (RT-1a) were administrated intravenously before CPB initiation. ResultsSerum concentrations of tumor necrosis factor-α, interleukin-6, and interleukin-1β in the MSC group were significantly lower compared with the control group after CPB. Similarly, mRNA expression of proinflammatory cytokines in the lung was lower in the MSC group. Allogeneic administration of FM-MSCs remarkably decreased the lung injury score, protected alveolar structure, inhibited neutrophil infiltration to the lung interstitium, and stimulated cytoprotective cytokine production in the lung. ConclusionsAllogeneic transplantation of FM-MSCs may be a potent strategy to prevent CPB-induced systemic inflammation and acute lung injury by suppressing the expression of inflammatory cytokines and promoting protective factors in the lung.

Developmental programming of breast cancer by soy isoflavones in ACI rats

Developmental programming of breast cancer by soy isoflavones in ACI rats

Whole Genome and RNA Sequencing Identifies Genetic Factors involved in Nephron Deficiency in the HSRA Congenital Solitary Kidney Rat

The HSRA rat is a unique polygenic model of congenital abnormalities of the kidney and urogenital tract, with 50–75% of offspring developing a single kidney. The model also exhibits nephron deficiency (~20% less nephrons) in the remaining kidney, glomerular and kidney hypertrophy, and elevated single nephron GFR, which leads to progressive kidney injury and decline in kidney function with age. A number of animal studies have provided an understanding of the physiological mechanism of injury, but it remains unknown the specific genetic factors that cause failure of one kidney to develop, as well as the mechanism of nephron deficiency in the remaining kidney. A recent genome‐wide association study (GWAS) performed by others using the heterogeneous stock rat (progenitor of the HSRA model), identified genomic loci on chromosomes (RNO) 4, 10, and 14 associated with the solitary kidney trait. The confidence interval for the RNO4 locus is ~4.2 Mb containing 14 genes, the RNO10 interval is ~1.5Mb containing 15 genes, and the RNO14 locus is consistent with locus linked to solitary kidney in the ACI rat. The whole genome was sequenced to a depth of 18X coverage using the Illumina NextSeq500 platform. Sequence alignment and annotation [BN reference genome (UCSC Rn5)], identified 1,776,635 SNP, 314,786 INDEL, and 25,346 structural variants. RNA sequencing of embryonic kidney isolated at key stages of nephrogenesis (E14.5, 15.5, and 16.5) between single kidney and two‐kidney control identified dysregulation of genes linked to cellular movement (p‐value= 2.36E‐06 ‐ 1.49E‐02 n=78/451), cell morphology (p‐value= 1.86E‐05 ‐ 1.49E‐02 n=82/451) and cell‐to‐cell signaling and interaction (p‐value= 8.38E‐05 ‐1.49E‐02 n=68/451). The top canonical pathway was associated with Wnt/b‐catenin (p‐value= 4.89E‐05) which includes Wnt2/Nlk candidates genes and is highly relevant to kidney development. Based on the GWAS, whole genome sequencing, and RNA sequencing, the causative genomic loci were refined to specific genes [c‐Kit (RNO14), Fam58b and Nlk (RNO10), and Met and Wnt2 (RNO4)] that could play a role in the solitary kidney trait and nephron deficiency in the HSRA model. In summary, the identification of the specific gene defect, modifier genes, and signaling pathways that lead to loss of one kidney and nephron deficiency will provide a mechanistic link between the solitary kidney genotype and the development of kidney dysfunction exhibited by the HSRA rat.Support or Funding InformationSupported by HL094446 (Garrett), UMMC, and Robert Hearin Foundation. Genomics Core [P20 GM103476 [MS‐INBRE‐(Elarsi)], P30GM103328 (CPN‐COBRE) and P20GM104357 (Obesity‐COBRE)

The reversed paradigm of chimerism induction: Donor conditioning with recipient-derived bone marrow cells as a novel approach for tolerance induction in vascularized composite allotransplantation.

To test a new approach of donor conditioning with recipient bone marrow cells (BMC) to induce tolerance in vascularized composite allograft (VCA) transplantation. Lewis rats' (recipients) BMC were stained with PKH-26. The ACI rats (donors) were conditioned with 80×106 Lewis BMC, 24 or 72 hours before VCA (groin flap) transplantation. Forty-eight VCA were performed between ACI donors and Lewis recipients. In groups I and II, donors were preconditioned (24 and 72 hours before transplantation, respectively), and recipients received 7-day anti-αβ-TCR/cyclosporine-A post-transplantation. In groups III and IV, donors were preconditioned (24 and 72 hours before transplantation, respectively), and recipients received no systemic immunosuppression. In group V, recipients received 7-day anti-αβ-TCR/cyclosporine-A post-transplantation. In group VI, recipients received no systemic immunosuppression. Assessment included evaluation of transplant viability and induction of donor-specific chimerism via flow cytometry, immunofluorescence, and PCR. Groups III, IV, and VI rejected allografts, at an average of 14 ± 5.2, 10 ± 2.7, and 8 ± 0.7 days. In groups I, II, and V, the mean survival was 80 ± 18.2 (p = 0.0002), 64 ± 27.4 (p = 0.001), and 30 ± 4.7 (p = 0.02) days. In groups I and II, donor-specific chimerism in the blood decreased from 8.8 ± 3.4% and 8.6 ± 3.4% on day 7 to 3.7 ± 1.32% (p = 0.02) and 4.7 ± 2.7% when the flaps manifested grade 3 rejection. The presence of PKH-26+ Lewis BMC was confirmed in the donor's blood, bone marrow, lymphoid organs, and liver (preconditioned at 24 and 72 hours). Donor preconditioning is a novel approach modifying recipient's responsiveness to donor allograft and prolonging the allograft survival under short-term immunosuppression. © 2015 Wiley Periodicals, Inc. Microsurgery 36:676-683, 2016.

Transarterial administration of integrin inhibitor loaded nanoparticles combined with transarterial chemoembolization for treating hepatocellular carcinoma in a rat model.

To compare the effect of transarterial chemoembolization (TACE) plus GRGDSP (Gly-Arg-Gly-Asp-Ser-Pro, integrin-inhibitor) loaded nanoparticles with TACE alone or TACE + GRGDSP in a rat model of liver tumor. Morris hepatoma 3924A tumors were implanted in the livers of 30 ACI rats. The ACI rats were divided randomly into three groups (10 animals each). Tumor volume before treatment (V1) was examined by magnetic resonance imaging (MRI), and then, after laparotomy and placement of a PE-10 catheter into the hepatic artery, the following interventional protocols were performed: TACE (mitomycin C + lipiodol + degradable starch microspheres) + GRGDSP loaded nanoparticles for group A; TACE + GRGDSP for group B (control group 1); TACE alone for group C (control group 2). Tumor volume (V2) was assessed by MRI and the mean ratio of the post-treatment to pretreatment tumor volumes (V2/V1) was calculated. Immunohistochemical analysis was performed to assess the quantification of matrix metalloprotein 9 (MMP-9) and vascular endothelial growth factor (VEGF) positive tumor cells in each treatment group. The mean tumor growth ratios (V2/V1) were 1.3649 ± 0.1194 in group A, 2.0770 ± 0.1595 in group B, and 3.2148 ± 0.1075 in group C. Compared with groups B and C, group A showed a significant reduction in tumor volume. Lower expression of MMP-9 and VEGF in hepatocellular carcinoma was observed in group A than in groups B and C. The angiogenesis of tumor was evaluated using anti-VEGF antibodies, and the metastasis of tumor was assessed using anti-MMP-9 antibody. MMP-9 and VEGF were expressed in all specimens. The immunoexpression of these proteins was confirmed by the presence of red cytoplasmic staining in tumor cells. Lower expression of MMP-9 and VEGF in hepatocellular carcinoma was observed in group A than in groups B and C. Transarterial administration of integrin inhibitor loaded nanoparticles combined with TACE evidently retards tumor growth and intrahepatic metastases compared with TACE alone or TACE plus integrin inhibitor in an animal model of hepatocellular carcinoma.

Abstract 4646: Cumin extract prevents estrogen-associated breast cancer in ACI rats

Abstract Spices are highly chemoprotective because of their antioxidant, antiproliferative, and anti-inflammatory activities. We have previously demonstrated significant chemoprotective effects of cumin seed powder (7.5%, w/w) against estrogen-induced mammary tumorigenesis in ACI rats by inhibiting cell proliferation as well as cellular and molecular markers. Here we report the inhibition of E2-mediated mammary tumorigenesis by cumin extract (1%, w/w) that is equivalent to the dietary dose in our previous study. Three extractions of cumin seeds with 80% aqueous ethanol followed by evaporation provided 13% of total dried extract (w/w). Groups of female ACI rats were given either AIN-93M diet or diet supplemented with cumin extract and then treated with subcutaneous 17ß-estradiol silastic implants (1.2 cm; 9 mg). Two additional groups were maintained on control or experimental diet. Rats received diet and water ad libitum. Five-six animals from each group were euthanized three weeks after the E2 treatment to determine the effect of interventions on early biomarkers. The remaining animals (n = 20-22) were euthanized when estrogen-treated group on control diet reached over 90% tumor incidence. Diet consumption and body weight gain was found to be largely unaffected by the cumin extract, suggesting that it was well tolerated. The first tumor incidence in control group was after 92 days, this was significantly delayed by 35 days in cumin extract treated group. Experimental diet significantly offset estrogen-related growth of pituitary prolactinomas as early as after three weeks (p = 0.019), the effect was more pronounced at tumor time point (p &amp;lt; 0.0001). At the end of the study (25 wks), the tumor incidence was found to be 96% in control group whereas only 45% animals had tumors in the intervention group. Significant reduction in average tumor volume (474 vs. 75 mm3) and tumor multiplicity (4.1 vs. 0.8 tumors/animal) was also observed by cumin extract compared to control. The mechanistic studies including effect on the plasma prolactin levels, and the cell proliferation marker, PCNA, estrogen-associated expression of the ERα and cyclin D1 in the mammary tissues are being evaluated. Together, our data show that cumin extract can significantly delay and prevent estrogen-mediated mammary tumorigenesis. This data further support our ultimate goal to develop these spice bioactives as clinically translatable chemopreventives and therapeutics against breast cancer. (Supported by CA-125152, Helmsley Fund, and Agnes Brown Duggan Endowment). Citation Format: Farrukh Aqil, Jeyaprakash Jeyabalan, Radha Munagala, Ramesh C. Gupta. Cumin extract prevents estrogen-associated breast cancer in ACI rats. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4646. doi:10.1158/1538-7445.AM2015-4646

Effects of Flaxseed Lignan Secoisolariciresinol Diglucosideon Preneoplastic Biomarkers of Cancer Progression in a Model of Simultaneous Breast and Ovarian Cancer Development

Breast cancer prevention efforts are focused increasingly on potentially beneficial dietary modifications due to their ease of implementation and wide acceptance. Secoisolariciresinol diglucoside (SDG) is a lignan found in high concentration in flaxseed that may have selective estrogen receptor modulator-like effects resulting in antiestrogenic activity in a high estrogen environment. In parallel with a human phase II prevention trial, female ACI rats (n = 8–10/group) received 0, 10, or 100 ppm SDG in the feed. The 100 ppm SDG treatment produced similar blood lignan levels as those observed in our human pilot study. Mammary and ovarian cancer progression were induced using local ovarian DMBA treatment and subcutaneous sustained release 17β-estradiol administered starting at 7 weeks of age. Mammary gland and ovarian tissues were collected at 3 mo after initiation of treatment and examined for changes in epithelial cell proliferation (Ki-67, cell counts), histopathology, and dysplasia scores, as well as expression of selected genes involved in proliferation, estrogen signaling, and cell adhesion. Treatment with SDG normalized several biomarkers in mammary gland tissue (dysplasia, cell number, and expression of several genes) that had been altered by carcinogen. There is no indication that SDG promotes preneoplastic progression in the ovarian epithelium.

Development and characterization of a novel rat model of estrogen-induced mammary cancer.

The ACI rat model of 17β-estradiol (E2)-induced mammary cancer is highly relevant for use in establishing the endocrine, genetic, and environmental bases of breast cancer etiology and identifying novel agents and strategies for preventing breast cancer. E2 treatment rapidly induces mammary cancer in female ACI rats and simultaneously induces pituitary lactotroph hyperplasia and adenoma. The pituitary tumors can result in undesired morbidity, which compromises long-term studies focused on mammary cancer etiology and prevention. We have defined the genetic bases of susceptibility to E2-induced mammary cancers and pituitary tumors and have utilized the knowledge gained in these studies to develop a novel inbred rat strain, designated ACWi, that retains the high degree of susceptibility to E2-induced mammary cancer exhibited by ACI rats, but lacks the treatment-related morbidity associated with pituitary lactotroph hyperplasia/adenoma. When treated with E2, female ACWi rats developed palpable mammary cancer at a median latency of 116 days, an incidence of 100% by 161 days and exhibited an average of 15.6 mammary tumors per rat following 196 days of treatment. These parameters did not differ from those observed for contemporaneously treated ACI rats. None of the E2-treated ACWi rats were killed before the intended experimental end point due to any treatment-related morbidity other than mammary cancer burden, whereas 20% of contemporaneously treated ACI rats exhibited treatment-related morbidity that necessitated premature killing. The ACWi rat strain is well suited for use by those in the research community, focusing on breast cancer etiology and prevention.

Genetic etiology of renal agenesis: fine mapping of Renag1 and identification of Kit as the candidate functional gene.

Congenital anomalies of the kidney and urogenital tract (CAKUT) occur in approximately 0.5% of live births and represent the most frequent cause of end-stage renal disease in neonates and children. The genetic basis of CAKUT is not well defined. To understand more fully the genetic basis of one type of CAKUT, unilateral renal agenesis (URA), we are studying inbred ACI rats, which spontaneously exhibit URA and associated urogenital anomalies at an incidence of approximately 10%. URA is inherited as an incompletely dominant trait with incomplete penetrance in crosses between ACI and Brown Norway (BN) rats and a single responsible genetic locus, designated Renag1, was previously mapped to rat chromosome 14 (RNO14). The goals of this study were to fine map Renag1, identify the causal genetic variant responsible for URA, confirm that the Renag1 variant is the sole determinant of URA in the ACI rat, and define the embryologic basis of URA in this rat model. Data presented herein localize Renag1 to a 379 kilobase (kb) interval that contains a single protein coding gene, Kit (v-kit Hardy-Zukerman 4 feline sarcoma viral oncogene homolog); identify an endogenous retrovirus-derived long terminal repeat located within Kit intron 1 as the probable causal variant; demonstrate aberrant development of the nephric duct in the anticipated number of ACI rat embryos; and demonstrate expression of Kit and Kit ligand (Kitlg) in the nephric duct. Congenic rats that harbor ACI alleles at Renag1 on the BN genetic background exhibit the same spectrum of urogenital anomalies as ACI rats, indicating that Renag1 is necessary and sufficient to elicit URA and associated urogenital anomalies. These data reveal the first genetic link between Kit and URA and illustrate the value of the ACI rat as a model for defining the mechanisms and cell types in which Kit functions during urogenital development.

Receptor activator for nuclear factor-κB ligand signaling promotes progesterone-mediated estrogen-induced mammary carcinogenesis.

Breast cancer is a leading cause of cancer-related death in women. Prolonged exposure to the ovarian hormones estrogen and progesterone increases the risk of breast cancer. Although estrogen is known as a primary factor in mammary carcinogenesis, very few studies have investigated the role of progesterone. Receptor activator for nuclear factor-κB (NF-κB) ligand (RANKL) plays an important role in progesterone-induced mammary carcinogenesis. However, the molecular mechanism underlying RANKL-induced mammary carcinogenesis remains unknown. In our current study, we show that RANKL induces glioma-associated oncogene homolog 1 (GLI-1) in estrogen-induced progesterone-mediated mammary carcinogenesis. In vivo experiments were carried out using ACI rats and in vitro experiments were carried out in MCF-7 cells. In ACI rats, mifepristone significantly reduced the incidence of mammary tumors. Likewise, mifepristone also inhibited the proliferation of MCF-7 cells. Hormone treatments induced RANKL, receptor activator of NF-κB (RANK), and NF-κB in a protein kinase B-dependent manner and inhibited apoptosis by activation of anti-apoptotic protein Bcl2 in mammary tumors and MCF-7 cells. Mechanistic studies in MCF-7 cells reveal that RANKL induced upstream stimulatory factor-1 and NF-κB, resulting in subsequent activation of their downstream target GLI-1. We have identified that progesterone mediates estrogen-induced mammary carcinogenesis through activation of GLI-1 in a RANKL-dependent manner.

Abstract 243: Tocopherols inhibit oxidative and nitrosative stress in estrogen-induced early mammary hyperplasia in ACI rats

Abstract Tocopherols (T), members of the vitamin E family, exist in four different forms designated as α, β, δ and γ. Due to their antioxidant properties, tocopherols are suggested to reduce the risk of cancer. α-T is known as the classic vitamin E as it is the major tocopherol found in plasma and tissues. However, some large scale clinical trials with α-T have provided inconclusive results. Recent studies from our laboratory and others indicate that δ-T and γ-T have stronger anti-cancer activities than α-T in vitro and in vivo. γ-T is the most common form of vitamin E in the U.S. diet, present in vegetable oils such as soybean, corn and cottonseed. The naturally occurring γ-T-enriched mixture of tocopherols (γ-TmT) has been reported to inhibit mammary tumorigenesis in estrogen receptor positive models of breast cancer. Using ACI rats, we investigated the chemopreventive activity of γ-TmT in the early stages of estrogen-induced mammary tumorigenesis. ACI rats provide an established model of rodent mammary carcinogenesis due to their high sensitivity to estrogen. Rats were subcutaneously implanted with 9 mg of 17β-estradiol (E2) in silastic tubings and fed with 0.3% γ-TmT diet for 1, 3, 7 and 14 days. Administration of γ-TmT gradually increased the levels of tocopherols and their metabolites in the serum and mammary glands of the rats from day 1 to 14. Histological analysis showed that estrogen induced mammary hyperplasia starting at day 3. However, the induction of mammary hyperplasia was not altered by dietary γ-TmT. Interestingly, mRNA expression of PPARγ, a nuclear receptor which inhibits cell proliferation and survival, was significantly increased by γ-TmT administration at 14 days. The oxidative and nitrosative stress markers, 8-oxo-dG and nitrotyrosine, respectively, were induced in the mammary tissues of E2-treated rats as early as day 1. γ-TmT decreased the levels of these markers starting from day 7. Serum level of 8-isoprostane, a marker of oxidative stress, was also decreased by γ-TmT. Elevated mRNA levels of a transcription factor Nrf2 and its downstream antioxidant enzymes, superoxide dismutase, catalase and glutathione peroxidase, were observed in the γ-TmT fed groups as early as day 1, indicating the induction of antioxidant response by γ-TmT. In conclusion, inhibition of oxidative, nitrosative stress and stimulation of antioxidant response are the primary effects of γ-TmT administration in the early stages of E2-induced mammary tumorigenesis in ACI rats. Citation Format: Soumyasri Das Gupta, Jae Young So, Joseph Wahler, Mao-Jung Lee, Chung S. Yang, Nanjoo Suh. Tocopherols inhibit oxidative and nitrosative stress in estrogen-induced early mammary hyperplasia in ACI rats. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 243. doi:10.1158/1538-7445.AM2014-243

Abstract 240: Natural antioxidants exhibit chemopreventive characteristics through the regulation of CNC-bZip transcription factors in estrogen-induced breast carcinogenesis

Abstract Epidemiological data and studies in rodent models strongly support the role of estrogens in the development of breast cancers. Exact mechanisms underlying the initiation and progression of estrogen-related cancers are not clear. Literature evidence and our studies strongly support the role of estrogen metabolism mediated oxidative stress in estrogen-induced breast carcinogenesis. We have recently demonstrated that antioxidants vitamin C (VC) or butylated hydroxyanisole (BHA) severely inhibit 17β-estradiol (E2)-induced breast tumor development in female ACI rats. The objective of this study was to characterize the role of CNC b-zip transcription factors in antioxidant-mediated prevention of breast cancer. Human non-neoplastic breast epithelial cell line MCF-10A was treated with E2, VC, VC + E2, Resveratrol (Res) and Res + E2 for up to 72 hrs. mRNA and protein expression levels of phase-II detoxifying enzymes SOD1, SOD2, SOD3, GPx, NQO1 and transcription factors from CNC b-zip family: Nrf1, Nrf2 and Nrf3 were quantified after treatment with E2 and compared with that of cells treated with antioxidants either alone or in combination with E2. The mRNA as well as protein expression levels of SOD3 and NQO1 were suppressed in MCF-10A cells treated with E2. There was no change in mRNA and protein expression levels of SOD1, SOD2 and GPX in MCF-10A cells treated with E2. Nrf2 mRNA and protein expression levels were also significantly suppressed in E2-treated MCF-10A cells. Vitamin C or Res treatment prevented E2-mediated decrease in SOD3, NQO1 and Nrf2 mRNA and protein expression levels. A significant increase in Nrf1 mRNA and protein expression levels in MCF-10A cells treated with E2 was noted. Further, treatment with antioxidants Res or VC also increased mRNA and protein expression levels of Nrf1. Nrf3 mRNA and protein expression levels were significantly increased in MCF-10A cells treated with E2. This induction was overcome by co-treatment with E2 and VC or Res. Our studies demonstrate that antioxidant-mediated protection against estrogen-induced breast cancer could be through up regulation of phase-II detoxifying enzymes via an Nrf-dependent pathway involving a complex interplay among Nrfs 1, 2 and 3. Note: This abstract was not presented at the meeting. Citation Format: Anwesha Chatterjee, Amruta Ronghe, Fatma Abdalla, Hari K. Bhat. Natural antioxidants exhibit chemopreventive characteristics through the regulation of CNC-bZip transcription factors in estrogen-induced breast carcinogenesis. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 240. doi:10.1158/1538-7445.AM2014-240

Validation of six genetic determinants of susceptibility to estrogen-induced mammary cancer in the rat and assessment of their relevance to breast cancer risk in humans.

When treated with 17β-estradiol, female ACI rats (Rattus norvegicus) rapidly develop mammary cancers that share multiple phenotypes with luminal breast cancers. Seven distinct quantitative trait loci that harbor genetic determinants of susceptibility to 17β-estradiol−induced mammary cancer have been mapped in reciprocal intercrosses between susceptible ACI rats and resistant Brown Norway (BN) rats. A panel of unique congenic rat strains has now been generated and characterized to confirm the existence of these quantitative trait loci, designated Emca3 through Emca9, and to quantify their individual effects on susceptibility to 17β-estradiol−induced mammary cancer. Each congenic strain carries BN alleles spanning an individual Emca locus, introgressed onto the ACI genetic background. Data presented herein indicate that BN alleles at Emca3, Emca4, Emca5, Emca6, and Emca9 reduce susceptibility to 17β-estradiol−induced mammary cancer, whereas BN alleles at Emca7 increase susceptibility, thereby confirming the previous interval mapping data. All of these Emca loci are orthologous to regions of the human genome that have been demonstrated in genome-wide association studies to harbor genetic variants that influence breast cancer risk. Moreover, four of the Emca loci are orthologous to loci in humans that have been associated with mammographic breast density, a biomarker of breast cancer risk. This study further establishes the relevance of the ACI and derived congenic rat models of 17β-estradiol−induced mammary cancer for defining the genetic bases of breast cancer susceptibility and elucidating the mechanisms through which 17β-estradiol contributes to breast cancer development.

Transplantation of Allogenic Fetal Membrane-Derived Mesenchymal Stem Cells Protects against Ischemia/Reperfusion-Induced Acute Kidney Injury

Mesenchymal stem cells (MSCs) are an attractive therapeutic cell source for treating renal diseases. MSC administration has been shown to improve renal function, although the underlying mechanisms are not completely understood. We recently showed that allogenic fetal membrane-derived MSCs (FM-MSCs), which are available noninvasively in large amounts, had a renoprotective effect in an experimental glomerulonephritis model. Here we investigated whether allogenic FM-MSC administration could protect kidneys from ischemia/reperfusion (I/R) injury. Lewis rats were subjected to right nephrectomy and left renal I/R injury by clamping the left renal artery as an acute kidney injury (AKI) model. After declamping, FM-MSCs (5 × 10(5) cells) obtained from major histocompatibility complex (MHC)-mismatched ACI rats were intravenously administered. I/R-injured rats exhibited increased serum creatinine and BUN, whereas FM-MSC administration significantly ameliorated renal function. Histological analysis revealed that FM-MSC administration significantly suppressed tubular apoptosis and infiltration of macrophages and T-cells. Administration of FM-MSCs mainly homed into the lung, but increased serum IL-10 levels. Of interest is that renoprotective effects of FM-MSCs were abolished by using anti-IL-10 neutralization antibody, suggesting that IL-10 would be one of the candidate factors to protect rat kidney from I/R injury in this model. We concluded that allogenic FM-MSC transplantation is a potent therapeutic strategy for the treatment of AKI.

Tocopherols inhibit oxidative and nitrosative stress in estrogen-induced early mammary hyperplasia in ACI rats.

Oxidative stress is known to play a key role in estrogen-induced breast cancer. This study assessed the chemopreventive activity of the naturally occurring γ-tocopherol-rich mixture of tocopherols (γ-TmT) in early stages of estrogen-induced mammary hyperplasia in ACI rats. ACI rats provide an established model of rodent mammary carcinogenesis due to their high sensitivity to estrogen. Female rats were implanted with 9 mg of 17β-estradiol (E2) in silastic tubings and fed with control or 0.3% γ-TmT diet for 1, 3, 7, and 14 d. γ-TmT increased the levels of tocopherols and their metabolites in the serum and mammary glands of the rats. Histological analysis revealed mammary hyperplasia in the E2 treated rats fed with control or γ-TmT diet. γ-TmT decreased the levels of E2-induced nitrosative and oxidative stress markers, nitrotyrosine, and 8-oxo-dG, respectively, in the hyperplastic mammary tissues. 8-Isoprostane, a marker of oxidative stress in the serum, was also reduced by γ-TmT. Noticeably, γ-TmT stimulated Nrf2-dependent antioxidant response in the mammary glands of E2 treated rats, evident from the induced mRNA levels of Nrf2 and its downstream antioxidant enzymes, superoxide dismutase, catalase, and glutathione peroxidase. Therefore, inhibition of nitrosative/oxidative stress through induction of antioxidant response is the primary effect of γ-TmT in early stages of E2-induced mammary hyperplasia. Due to its cytoprotective activity, γ-TmT could be a potential natural agent for the chemoprevention of estrogen-induced breast cancer.

Ept7 influences estrogen action in the pituitary gland and body weight of rats

Estrogens control many aspects of pituitary gland biology, including regulation of lactotroph homeostasis and synthesis and secretion of prolactin. In rat models, these actions are strain specific and heritable, and multiple quantitative trait loci (QTL) have been mapped that impact the responsiveness of the lactotroph to estrogens. One such QTL, Ept7, was mapped to RNO7 in female progeny generated in an intercross between BN rats, in which the lactotroph population is insensitive to estrogens, and ACI rats, which develop lactotroph hyperplasia/adenoma and associated hyperprolactinemia in response to estrogen treatment. The primary objective of this study was to confirm the existence of Ept7 and to quantify the impact of this QTL on responsiveness of the pituitary gland of female and male rats to 17β-estradiol (E2) and diethylstilbestrol (DES), respectively. Secondary objectives were to determine if Ept7 influences the responsiveness of the male reproductive tract to DES and to identify other discernible phenotypes influenced by Ept7. To achieve these objectives, a congenic rat strain that harbors BN alleles across the Ept7 interval on the genetic background of the ACI strain was generated and characterized to define the effect of administered estrogens on the anterior pituitary gland and male reproductive tissues. Data presented herein indicate Ept7 exerts a marked effect on development of lactotroph hyperplasia in response to estrogen treatment, but does not affect atrophy of the male reproductive tissues in response to hormone treatment. Ept7 was also observed to exert gender specific effects on body weight in young adult rats.

Methylation and miRNA Effects of Resveratrol on Mammary Tumors vs. Normal Tissue

We reported that resveratrol decreased DNA methyltransferase (DNMT) 1 and 3b expression in vitro and demethylates tumor suppressor RASSF-1a in women at increased breast cancer risk. We investigated the effects of resveratrol on DNMT and miRNA expression in normal and tumor mammary tissue in a rodent model of estrogen dependent mammary carcinoma. Eighty-nine female ACI rats received estradiol plus: low dose (lo) resveratrol, high dose (hi) resveratrol, 5-aza-2-deoxycytidine (Aza), a known inhibitor of DNMTs, or control (no additional treatment). After 21 wk of treatment, animals were sacrificed and mammary glands harvested. Matched tumor/normal tissues were available from 36 rats. DMNT3b (but not DNMT1) differed in tumor vs. normal tissue after lo (P = .04) and hi (P = .007) resveratrol and Aza treatment. With hi resveratrol, DNMT3b decreased in tumor but increased normal tissue. Hi resveratrol increased miR21, −129, −204, and −489 >twofold in tumor and decreased the same miRs in normal tissue 10–50% compared to control. There was an inverse association between DNMT3b and miR129, −204, and −489 in normal and/or tumor tissue. Treatment with resveratrol differentially influences tumor vs. normal tissue DNMT3b and miRNA expression. This mechanism of action of resveratrol to influence mammary carcinogenesis warrants further investigation.