Riluzole Suppresses Growth and Enhances Response to Endocrine Therapy in ER+ Breast Cancer

Background

Resistance to endocrine therapy in estrogen receptor-positive (ER+) breast cancer remains a significant clinical problem. Riluzole is FDA-approved for the treatment of amyotrophic lateral sclerosis. A benzothiazole-based glutamate release inhibitor with several context-dependent mechanism(s) of action, riluzole has shown antitumor activity in multiple malignancies, including melanoma, glioblastoma, and breast cancer. We previously reported that the acquisition of tamoxifen resistance in a cellular model of invasive lobular breast cancer is accompanied by the upregulation of GRM mRNA expression and growth inhibition by riluzole.

Methods

We tested the ability of riluzole to reduce cell growth, alone and in combination with endocrine therapy, in a diverse set of ER+ invasive ductal and lobular breast cancer-derived cell lines, primary breast tumor explant cultures, and the estrogen-independent, ESR1-mutated invasive lobular breast cancer patient-derived xenograft model HCI-013EI.

Results

Single-agent riluzole suppressed the growth of ER+ invasive ductal and lobular breast cancer cell lines in vitro, inducing a histologic subtype-associated cell cycle arrest (G0-G1 for ductal, G2-M for lobular). Riluzole induced apoptosis and ferroptosis and reduced phosphorylation of multiple prosurvival signaling molecules, including Akt/mTOR, CREB, and Fak/Src family kinases. Riluzole, in combination with either fulvestrant or 4-hydroxytamoxifen, additively suppressed ER+ breast cancer cell growth in vitro. Single-agent riluzole significantly inhibited HCI-013EI patient-derived xenograft growth in vivo, and the combination of riluzole plus fulvestrant significantly reduced proliferation in ex vivo primary breast tumor explant cultures.

Conclusion

Riluzole may offer therapeutic benefits in diverse ER+ breast cancers, including lobular breast cancer.

Environmentally Induced Sperm RNAs Transmit Cancer Susceptibility to Offspring in a Mouse Model

DNA sequence accounts for the majority of disease heritability, including cancer. Yet, not all familial cancer cases can be explained by genetic factors. It is becoming clear that environmentally induced epigenetic inheritance occurs and that the progeny's traits can be shaped by parental environmental experiences. In humans, epidemiological studies have implicated environmental toxicants, such as the pesticide DDT, in intergenerational cancer development, including breast and childhood tumors. Here, we show that the female progeny of males exposed to DDT in the pre-conception period have higher susceptibility to developing aggressive tumors in mouse models of breast cancer. Sperm of DDT-exposed males exhibited distinct patterns of small non-coding RNAs, with an increase in miRNAs and a specific surge in miRNA-10b levels. Remarkably, embryonic injection of the entire sperm RNA load of DDT-exposed males, or synthetic miRNA-10b, recapitulated the tumor phenotypes observed in DDT offspring. Mechanistically, miR-10b injection altered the transcriptional profile in early embryos with enrichment of genes associated with cell differentiation, tissue and immune system development. In adult DDT-derived progeny, transcriptional and protein analysis of mammary tumors revealed alterations in stromal and in immune system compartments. Our findings reveal a causal role for sperm RNAs in environmentally induced inheritance of cancer predisposition and, if confirmed in humans, this could help partially explain some of the "missing heritability" of breast, and other, malignancies.

OR16-5 Riluzole suppresses growth and enhances response to endocrine therapy in ER+ breast cancer

Approximately 75% of breast cancers are classified as hormone receptor-positive, most of which are estrogen receptor alpha-positive (ER+), which is the primary driver of growth in these tumors. Consequently, endocrine or anti-estrogen therapy is used for treatment. However, despite the benefits of endocrine therapeutics, treatment-resistant relapse is a significant problem that affects 30-50% of patients who initially respond to endocrine therapy. Therefore, studying resistance to endocrine therapy is critical for breast cancer research.We have shown that invasive lobular breast cancer (ILC) cells resistant to the anti-estrogen tamoxifen increase their expression of metabotropic glutamate receptors (GRMs/mGluRs). GRMs are well-known to play important roles in learning and memory in the brain and protect neurons from excitotoxicity (cell death caused by prolonged exposure to neurotransmitters). It is now appreciated that this pro-survival function of GRMs can be highjacked by cancer cells, including breast cancer. Thus, targeting GRM signaling could prove a valuable therapeutic strategy. We chose to target the GRM signaling pathway with the FDA-approved drug Riluzole currently being used to treat amyotrophic lateral sclerosis.In this study, we test the ability of Riluzole to reduce cell growth, alone and in combination with endocrine therapy, in a diverse set of ER+ invasive ductal and lobular breast cancer-derived cell lines, primary breast tumor explant cultures, and the estrogen-independent, ESR1-mutated, ILC-derived patient-derived xenograft model HCI-013EI. In addition to measuring tumor growth rate and size, primary tumors and organs were collected for immunohistochemistry analysis.Riluzole as a single agent suppressed the growth of ER+ invasive ductal and lobular breast cancer cell lines in vitro, inducing differential histologic subtype-associated cell cycle arrest (G0-G1 for ductal, G2-M for lobular). In tamoxifen-resistant ILC cells, Riluzole induced apoptotic and ferroptotic cell death, and inhibited phosphorylation of focal adhesion kinase. Riluzole combined with either fulvestrant or 4-hydroxytamoxifen additively or synergistically suppressed ER+ breast cancer cell growth in vitro. Using proliferating cell nuclear antigen (PCNA) staining as a proxy for cell proliferation, the combination of Riluzole plus Fulvestrant significantly reduced PCNA in a patient-derived explant model (t-test p = 0.013). The in vivo experiment showed reduced tumor size and growth between the control and combination treatments. However, unlike in the in vitro experiment, there was little difference between the single-agent fulvestrant and the combination groups. The observed difference between the in vitro and in vivo study may be attributed to the bioavailability of Riluzole in mice.In conclusion, our results show that Riluzole enhances response to endocrine therapy in ER+ breast cancer.

Presentation: Sunday, June 12, 2022 12:00 p.m. - 12:15 p.m.

Abstract LB229: Environmentally-induced epigeneticinheritance of cancer: Paternal exposure to pesticides induces intergenerational programming of breast cancer predisposition via sperm small RNAs

Background: DNA sequence accounts for the majority of disease heritability, including cancer. However, it is becoming clear that environmentally-induced epigenetic inheritance of disease can also occur. Epidemiological studies have shown that parental exposure to the pesticide DDT and other environmental toxicants is associated with increased tumor development, particularly breast cancer, in offspring. Here, we tested whether paternal exposure to DDT could lead to intergenerational increase in breast cancer development using a mouse model. We also investigated the mechanisms of intergenerational transmission.Methods: Male mice (c57bl/6) were exposed to DDT or to a control-vehicle (CO) solution and used for sperm collection or mating with unexposed females to produce the DDT or CO daughters. In another experiment, normal mouse embryos (zygote stage) were injected with purified sperm RNAs or synthetic miRNA-10b and implanted into surrogate mothers to produce RNA-injected offspring. DDT daughters or RNA injected females were used to study breast cancer development (carcinogen-induced or orthotopic models) and metabolic parameters. Paternal sperm was used for RNA-seq analysis and miRNA expression levels. Results: Pre-conception paternal DDT exposure altered the sperm small non-coding RNA load, with an increase in miRNAs and a specific surge in miRNA-10b levels. DDT offspring weighed less at birth and at weaning, but became overweight and showed metabolic dysfunction in adulthood compared to CO. DDT daughters also showed increased mammary tumorigenesis, developing more aggressive tumors that grew faster than in CO. This tumor phenotype was linked to suppression of the AMPK energy sensing pathway and mTOR activation in mammary tissues. Remarkably, embryonic injection of purified DDT sperm RNA or synthetic miRNA-10b recapitulated the mammary gland and tumor phenotypes observed in DDT daughters. Conclusions: To our knowledge, this is the first report of an association between paternal DDT exposure and breast cancer in offspring. Paternal DDT-induced programming of breast cancer development in daughters is mechanistically linked to sperm RNAs and, more specifically, miRNA-10b. The impact of DDT and other endocrine disrupting chemicals on sperm and programming of breast and other cancers in offspring needs to be evaluated in humans.

Citation Format: Raquel Santana Da Cruz, Hong Cao, Camile C. Fontelles, Apsra Nasir, Alexandra K. Gonsiewski, M. Idalia Cruz, Lu Jin, Sonia de Assis. Environmentally-induced epigeneticinheritance of cancer: Paternal exposure to pesticides induces intergenerational programming of breast cancer predisposition via sperm small RNAs [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2021; 2021 Apr 10-15 and May 17-21. Philadelphia (PA): AACR; Cancer Res 2021;81(13_Suppl):Abstract nr LB229.

Abstract A03: Preconception paternal DDT exposure and programming of metabolic dysfunction and breast cancer in offspring

The pesticide dichlorodiphenyltrichloroethane or DDT was widely used in agriculture or to combat insect-borne diseases until the 1970s in the United States and the 1980s in Europe. It continues to be used in developing countries to combat malaria or illegally to protect crops. Because of its prolonged half-life, DDT is a persistent environmental pollutant that still can detected in the American population, particularly in minorities and recent immigrants. Epidemiologic studies have shown that early-life (in utero and early childhood) exposure to DDT is associated with a four-fold increase in breast cancer risk in women, and these findings are supported by animal studies. While maternal DDT exposure in pregnancy has been linked to breast cancer in offspring, the effects of paternal DDT exposure on their progeny’s breast cancer development have not been investigated. Environmental exposures can induce epigenetic changes in paternal sperm and affect the risk of disease in their offspring. Here, we evaluated the effects of preconception exposure to DDT on the male sperm epigenome and programming of offspring’s susceptibility to breast cancer, using a mouse model. Male mice were exposed to DDT (1.7mg/kg body weight) by oral gavage in the preconception window. DDT and control-vehicle (CO) males were then used for sperm collection or housed with female mice, with free access to a standard chow diet, for three days. Pregnancy onset was assessed by the presence of a vaginal plug. The weight and number of pups per litter were determined two days after birth. Pups were weaned at 21 days of age and fed a standard chow diet for the extent of the study. Offspring were weighed weekly and used to study metabolic parameters. Mammary tumors were induced by administration of 15mg of medroxyprogesterone to six-week-old female offspring, followed by oral administration of 1mg 7,12-dimethylbenz[a]anthracene once a week for 3 weeks. RNA extracted from sperm CO and DDT males was used for small RNA-seq analysis. Preconception exposure to DDT altered small noncoding RNAs (e.g., miRNAs and tRNAs) in paternal sperm. In line with that, offspring of DDT-exposed fathers had a significant decrease in birth and weaning weights compared to controls. Further, DDT offspring showed metabolic dysfunction. Compared to CO, female offspring of DDT fathers had significantly accelerated breast tumor growth and a nonsignificant increase in mammary tumor incidence and shorter tumor latency. These tumor phenotypes were linked to mammary tissue inhibition of AMPK, a central metabolic sensor, and increased mTOR activity. In conclusion, our findings support a role for DDT exposure from the paternal lineage in metabolic dysfunction and increased breast cancer development in the offspring. Defining the mechanism by which paternal exposures to EDC such as DDT can promote breast cancer development in offspring is critical to identifying early detection/preventive approaches or treatments for this malignancy in a subset of women.

Citation Format: Raquel Santana da Cruz, Hong Cao, Camile Fontelles, Apsra Nasir, Volkan Tekam, M. Idalia Cruz, Lu Jin, Sonia de Assis. Preconception paternal DDT exposure and programming of metabolic dysfunction and breast cancer in offspring [abstract]. In: Proceedings of the AACR Special Conference on Environmental Carcinogenesis: Potential Pathway to Cancer Prevention; 2019 Jun 22-24; Charlotte, NC. Philadelphia (PA): AACR; Can Prev Res 2020;13(7 Suppl): Abstract nr A03.

Theaphenon E prevents fatty liver disease and increases CD4+ T cell survival in mice fed a high-fat diet

BACKGROUND & AIMS

Obesity is a major cause of non-alcoholic fatty liver disease (NAFLD). NAFLD is an epidemic affecting nearly 34% of the adult population in the US. As a chronic inflammatory disease, NAFLD influences the immune system by dysregulating T-cell activity. Remedies for the adverse effects on the immune system are urgently needed. We studied Theaphenon E (TE), a standardized formulation of green tea extract, on the adverse effects of NAFLD in C57BL/6J mice fed a high fat diet (HFD).

METHODS

Mice received HFD, low fat diet (LFD) or HFD+2% TE for 35 weeks. Hepatic lipid accumulation, cell proliferation, apoptosis and CD4+T lymphocytes were measured throughout the bioassay. The hepatic composition of fatty acids was determined. The effects of epigallocatechin gallate (EGCG) metabolites on lipid accumulation in mouse and primary human liver cells were studied.

RESULTS

Unlike mice receiving HFD, mice on HFD+2% TE maintained normal liver to body weight ratios with low levels of alanine and aspartate aminotransferase (ALT and AST). Hepatic lipid accumulation was observed in HFD mice, accompanied by increased proliferation, reduced apoptosis and loss of CD4+ T lymphocytes. TE significantly inhibited lipid accumulation, decreased proliferation, induced apoptosis and increased CD4+ T cell survival in HFD mice. It was found that the EGCG metabolite EGC-M3 reduced lipid accumulation in mouse and human hepatocytes. Linoleic acid showed the largest increase (2.5-fold) in livers of mice on a HFD and this increase was significantly suppressed by TE.

CONCLUSIONS

Livers of HFD-fed mice showed lipid accumulation, increased proliferation, reduced apoptosis, elevated linoleic acid and loss of CD4+ T cells. TE effectively ameliorated all of these adverse effects.

Parental obesity programs pancreatic cancer development in offspring

Epidemiological studies suggest that timing of obesity onset - and underlying metabolic dysfunction - is important in determining pancreatic cancer rates: early and young adult abdominal overweight/obesity is more strongly associated with this cancer than obesity that develops later in life. Parental obesity and overweight are associated with metabolic dysfunction and obesity in their children. Here, we evaluated the impact of parental overweight on offspring's susceptibility of pancreatic cancer using the P48Cre/+/KrasG12D/+ mouse model. Male mice were fed an obesity-inducing diet (OID) before conception and mated with females raised on a control diet (CO) to generate the offspring. In a separate experiment, pregnant dams were fed CO or OID throughout gestation. The resulting OID offspring from the maternal (OID-m) or paternal lineage (OID-p) were used to study body weight, metabolic parameters and pancreatic cancer development and for molecular analysis. Parental obesity increased offspring's body weight at birth, weaning and in adulthood compared to CO, with gender- and genotype-specific differences. OID-p and OID-m offspring showed metabolic disorder and accelerated development of high-grade PanIN/PDAC. OID offspring also had higher rates of acinar-to-ductal reprogramming assessed by CPA1+/SOX9+-positive pancreatic cells. Levels of Tenascin C (TNC), an ECM glycoprotein shown to suppress apoptosis, were elevated in OID offspring, particularly females. In line with that, OID offspring displayed increased collagen content and decreased apoptosis in pancreatic lesions compared to CO. An ancestral history of obesity through either the paternal or maternal lineages increases offspring's susceptibility to pancreatic cancer development.

Prevention of Lipid Peroxidation-derived Cyclic DNA Adduct and Mutation in High-Fat Diet-induced Hepatocarcinogenesis by Theaphenon E

Obesity is associated with cancer risk and its link with liver cancer is particularly strong. Obesity causes non-alcoholic fatty liver disease (NAFLD) that could progress to hepatocellular carcinoma (HCC). Chronic inflammation likely plays a key role. We carried out a bioassay in the high-fat diet (HFD)-fed C57BL/6J mice to provide insight into the mechanisms of obesity-related HCC by studying γ-OHPdG, a mutagenic DNA adduct derived from lipid peroxidation. In an 80-week bioassay, mice received a low-fat diet (LFD), high-fat diet (HFD), and HFD with 2% Theaphenon E (TE) (HFD+TE). HFD mice developed a 42% incidence of HCC and LFD mice a 16%. Remarkably, TE, a standardized green tea extract formulation, completely blocked HCC in HFD mice with a 0% incidence. γ-OHPdG measured in the hepatic DNA of mice fed HFD and HFD+TE showed its levels increased during the early stages of NAFLD in HFD mice and the increases were significantly suppressed by TE, correlating with the tumor data. Whole-exome sequencing showed an increased mutation load in the liver tumors of HFD mice with G>A and G>T as the predominant mutations, consistent with the report that γ-OHPdG induces G>A and G>T. Furthermore, the mutation loads were significantly reduced in HFD+TE mice, particularly G>T, the most common mutation in human HCC. These results demonstrate in a relevant model of obesity-induced HCC that γ-OHPdG formation during fatty liver disease may be an initiating event for accumulated mutations that leads to HCC and this process can be effectively inhibited by TE. Cancer Prev Res; 11(10); 665-76. ©2018 AACR.

Paternal malnutrition programs breast cancer risk and tumor metabolism in offspring

Background

While many studies have shown that maternal factors in pregnancy affect the cancer risk for offspring, few studies have investigated the impact of paternal exposures on their progeny’s risk of this disease. Population studies generally show a U-shaped association between birthweight and breast cancer risk, with both high and low birthweight increasing the risk compared with average birthweight. Here, we investigated whether paternal malnutrition would modulate the birthweight and later breast cancer risk of daughters.

Methods

Male mice were fed AIN93G-based diets containing either 17.7% (control) or 8.9% (low-protein (LP)) energy from protein from 3 to 10 weeks of age. Males on either group were mated to females raised on a control diet. Female offspring from control and LP fathers were treated with 7,12-dimethylbenz[a]anthracene (DMBA) to initiate mammary carcinogenesis. Mature sperm from fathers and mammary tissue and tumors from female offspring were used for epigenetic and other molecular analyses.

Results

We found that paternal malnutrition reduces the birthweight of daughters and leads to epigenetic and metabolic reprogramming of their mammary tissue and tumors. Daughters of LP fathers have higher rates of mammary cancer, with tumors arising earlier and growing faster than in controls. The energy sensor, the AMP-activated protein kinase (AMPK) pathway, is suppressed in both mammary glands and tumors of LP daughters, with consequent activation of mammalian target of rapamycin (mTOR) signaling. Furthermore, LP mammary tumors show altered amino-acid metabolism with increased glutamine utilization. These changes are linked to alterations in noncoding RNAs regulating those pathways in mammary glands and tumors. Importantly, we detect alterations in some of the same microRNAs/target genes found in our animal model in breast tumors of women from populations where low birthweight is prevalent.

Conclusions

Our study suggests that ancestral paternal malnutrition plays a role in programming offspring cancer risk and phenotype by likely providing a metabolic advantage to cancer cells.

Electronic supplementary material

The online version of this article (10.1186/s13058-018-1034-7) contains supplementary material, which is available to authorized users.

Abstract 4323: Ancestral obesity and early life metabolic dysfunction accelerates acinar-to-ductal reprogramming and PanIN/PDAC development in the P48Cre/+ /KrasG120/+ mouse model

Pancreatic cancer is virtually an incurable malignancy, with overall 5-year survival rates of about 7%. Excess body weight and metabolic dysfunction are believed to account for up to 50% of all pancreatic cancers. Epidemiological studies suggest that timing of obesity—and underlying metabolic dysfunction—onset is important in determining pancreatic cancer rates: Early and young adult abdominal obesity is more strongly associated with this cancer than obesity that develops later in life. However, the mechanisms behind this association are not understood. Children of obese parents are more likely to develop overweight, insulin resistance and diabetes. Here, we evaluated the effects of paternal overweight in the susceptibility of pancreatic cancer in offspring using the P48Cre/+ /KrasG120/+ mouse model of pancreatic cancer. LSL-KrasG120/+ and P48Cre/+ male mice were fed either an obesity-inducing (OID) or control (CO) diet for 8 weeks from weaning to sexual maturity. At the end of this period, OID- and CO-fed male mice were housed with female mice, with free access to CO diet, for 3 days. Pregnant dams were kept on the CO diet during pregnancy and after giving birth. Pups were weaned from mothers at 21 days of age, fed a standard chow diet for the extent of the study and weighed weekly. While both female and male OID offspring had higher weight at birth (p=0.005), only OID females were heavier at weaning (p=0.02) compared to CO. Those gender-specific differences were also observed in metabolic parameters with OID male, but not female, offspring showing impaired glucose tolerance (p<0.05) compared to CO. Interestingly, OID offspring also had significantly higher rates of acinar-to-ductal reprogramming as assessed by the ratio of CPA1,+Sox9+ pancreatic cells. Accordingly, we also observed accelerated development of high grade PanIN at 2 and 6-8 months of age in OID offspring compared to CO of the P48Cre/+ /KrasG120/+ genotype (p=0.02; p=0.007). Additionally, we found that the expression of Tenascin C (TNC), an ECM glycoprotein shown to suppress apoptosis, was upregulated in OID offspring (p=0.03). In line with that, OID offspring displayed increased (p=0.03) collagen content and decreased apoptosis (p=0.02) in pancreatic lesions compared to CO. In conclusion, an ancestral history of overweight through the paternal lineage and ensuing metabolic dysfunction in offspring increases their susceptibility to pancreatic cancer development. This increase was associated with higher acinar-to-ductal reprogramming and TNC expression, and reduced apoptosis in pancreatic lesions. While the exact mechanisms still need to be elucidated, our study offers some insights on why early obesity and metabolic dysfunction are more strongly associated to pancreatic cancer in humans.

Citation Format: Raquel Santana, Johan Clarke, Ana Cristina Curi, Ali Baird, M Idalia Cruz, Bhaskar Kallakury, Sonia de Assis. Ancestral obesity and early life metabolic dysfunction accelerates acinar-to-ductal reprogramming and PanIN/PDAC development in the P48Cre/+ /KrasG120/+ mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 4323.

Endoplasmic Reticulum Stress Protein GRP78 Modulates Lipid Metabolism to Control Drug Sensitivity and Antitumor Immunity in Breast Cancer

The unfolded protein response is an endoplasmic reticulum stress pathway mediated by the protein chaperone glucose regulated-protein 78 (GRP78). Metabolic analysis of breast cancer cells shows that GRP78 silencing increases the intracellular concentrations of essential polyunsaturated fats, including linoleic acid. Accumulation of fatty acids is due to an inhibition of mitochondrial fatty acid transport, resulting in a reduction of fatty acid oxidation. These data suggest a novel role of GRP78-mediating cellular metabolism. We validated the effect of GRP78-regulated metabolite changes by treating tumor-bearing mice with tamoxifen and/or linoleic acid. Tumors treated with linoleic acid plus tamoxifen exhibited reduced tumor area and tumor weight. Inhibition of either GRP78 or linoleic acid treatment increased MCP-1 serum levels, decreased CD47 expression, and increased macrophage infiltration, suggesting a novel role for GRP78 in regulating innate immunity. GRP78 control of fatty acid oxidation may represent a new homeostatic function for GRP78. Cancer Res; 76(19); 5657-70. ©2016 AACR.

Maternal intake of high n-6 polyunsaturated fatty acid diet during pregnancy causes transgenerational increase in mammary cancer risk in mice

Background

Maternal and paternal high-fat (HF) diet intake before and/or during pregnancy increases mammary cancer risk in several preclinical models. We studied if maternal consumption of a HF diet that began at a time when the fetal primordial germ cells travel to the genital ridge and start differentiating into germ cells would result in a transgenerational inheritance of increased mammary cancer risk.

Methods

Pregnant C57BL/6NTac mouse dams were fed either a control AIN93G or isocaloric HF diet composed of corn oil high in n-6 polyunsaturated fatty acids between gestational days 10 and 20. Offspring in subsequent F1–F3 generations were fed only the control diet.

Results

Mammary tumor incidence induced by 7,12-dimethylbenz[a]anthracene was significantly higher in F1 (p < 0.016) and F3 generation offspring of HF diet-fed dams (p < 0.040) than in the control offspring. Further, tumor latency was significantly shorter (p < 0.028) and burden higher (p < 0.027) in F1 generation HF offspring, and similar trends were seen in F3 generation HF offspring. RNA sequencing was done on normal mammary glands to identify signaling differences that may predispose to increased breast cancer risk by maternal HF intake. Analysis revealed 1587 and 4423 differentially expressed genes between HF and control offspring in F1 and F3 generations, respectively, of which 48 genes were similarly altered in both generations. Quantitative real-time polymerase chain reaction analysis validated 13 chosen up- and downregulated genes in F3 HF offspring, but only downregulated genes in F1 HF offspring. Ingenuity Pathway Analysis identified upregulation of Notch signaling as a key alteration in HF offspring. Further, knowledge-fused differential dependency network analysis identified ten node genes that in the HF offspring were uniquely connected to genes linked to increased cancer risk (ANKEF1, IGFBP6, SEMA5B), increased resistance to cancer treatments (SLC26A3), poor prognosis (ID4, JAM3, TBX2), and impaired anticancer immunity (EGR3, ZBP1).

Conclusions

We conclude that maternal HF diet intake during pregnancy induces a transgenerational increase in offspring mammary cancer risk in mice. The mechanisms of inheritance in the F3 generation may be different from the F1 generation because significantly more changes were seen in the transcriptome.

Electronic supplementary material

The online version of this article (doi:10.1186/s13058-017-0866-x) contains supplementary material, which is available to authorized users.

Abstract 2404: Paternal intake of an obesity-inducing diet before conception modulates the risk of pancreatic cancer in offspring in a mouse model

Pancreatic cancer is a mostly untreatable malignancy, with 5-year survival rates of about 5%. Life-style and dietary factors have been associated with pancreatic cancer risk. Particularly, the consumption of high-fat diets and obesity (and underlying metabolic dysfunction) have been linked to increased susceptibility to this cancer. Recent studies have shown that the paternal diet and life-style can have a significant influence on offspring’s health via epigenetic information transmitted in the germ-line. Paternal overweight before conception has been shown to increase offspring’s susceptibility of developing metabolic diseases and some types of cancer. Here, we evaluated the effects of paternal overweight in the susceptibility of pancreatic cancer in offspring using the P48Cre/+ /KrasG120/+ mouse model of pancreatic cancer. LSL-KrasG120/+ and P48Cre/+ male mice were fed either an obesity-inducing (OID) or control (CO) diet for 8 weeks from weaning to sexual maturity. After this period, OID-fed and CO-fed male mice were housed together with 7 week-old female mice, with free access to CO diet, for 3 days. Pregnant dams were kept on the CO diet during pregnancy and after giving birth. Pups were weaned from mothers at 21 days of age, fed a standard chow diet for the extent of the study and weighed weekly. The offspring of CO or OID fathers were used to study body weight, metabolic parameters and pancreatic cancer development. Fathers fed an OID gained significantly more weight (CO 15.7±1.0g; OID 19.7±1.3g, p=0.02) and had higher leptin levels (p=0.04), compare to CO group fathers. Body weight analyses of OID and CO offspring, showed gender-specific effects. While the OID female offspring had higher weight at birth (p=0.005) and at weaning (p=0.02), compare to CO group, no significant differences were observed between the CO and OID male offspring. Those gender-specific differences were also observed in metabolic parameters such GTT with the OID male, but not female, offspring showing impaired glucose tolerance (p=0.0004) compared to CO. While the monitoring period is still ongoing, 8-week old OID offspring present gender-specific differences in susceptibility to pancreatic cancer: Males OID offspring have higher number/area (481±25; 2.6±0.3) of pancreatic intraepithelial neoplasia (PanIn), compared to CO (359±61; 2.0±0.5). On the other hand, female OID offspring have similar levels of PanIn, but have higher incidence of PDACs compare to CO. In conclusion, an ancestral history of overweight through the paternal lineage may be associated with an increased susceptibility to pancreatic cancer development in adulthood. The mechanisms mediating this effect remain to be elucidated.

Citation Format: Raquel Santana Da Cruz, Johan Clarke, Ali Baird, Hong Cao, Carlos Benitez, M. Idalia Cruz, Sonia De Assis. Paternal intake of an obesity-inducing diet before conception modulates the risk of pancreatic cancer in offspring in a mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 2404. doi:10.1158/1538-7445.AM2017-2404

Abstract 1257: Paternal sub-optimal nutrition leads to programming of daughters' breast cancer risk in a mouse model

Background: Dietary patterns are known to induce epigenetic changes in paternal sperm. Acquired epigenetic traits have been shown to be transmitted from parents to offspring via the germ-line (eggs and sperm) and modulate disease risk in offspring. We have shown before that paternal overweight around the time of conception leads to reprogramming of the mammary gland tissue and breast cancer risk in the offspring. Here, we investigated whether paternal sub-optimal nutrition (low protein diet) could epigenetically reprogram the father's germ-line and alter daughters' likelihood of developing breast cancer, using a mouse model.

Methods: Male mice were fed control (Con) or low-protein (LP) diets from weaning until sexual maturity; at this point, males were housed together with female mice reared on control diet. Once a vaginal plug was detected, males were euthanized for sperm collection. Pregnant dams were fed the control diet throughout pregnancy and after giving birth. Pups were fed the control diet throughout the experiment. A subset of female offspring was euthanized for mammary tissue harvesting on post-natal day (PND) 50, which was used for morphologic and molecular analyses. Another sub-set of female offspring was treated with 9,12-dimethylbenz[a]anthracene (DMBA) to induce mammary tumors. 

Results: We found that male LP consumption alters the non-coding RNA content and DNA methylation patterns of the sperm in agreement with previous findings. We also observed that, compared to Con offspring, the female offspring of LP fathers had lower birth weight (p=0.035). This decrease in body weight persisted through sexual maturity when females begun to gain more weight than their control counterparts (p&gt;0.001). In addition, mammary glands of LP offspring were larger(p=0.02) and had increased epithelial density (p=0.001) when compared to Con on PND50. In addition, we found that LP mammary glands had epigenetic alterations, including in DNA methylation and the miRNA expression profiles. These changes in normal mammary tissue were associated with higher rates of DMBA-induced mammary tumor (p=0.04), increased tumor growth (p=0.03) and reduced tumor latency in LP offspring (p=0.03). Mammary tumors of LP offspring had lower rates of apoptosis, which may explain the increased tumor growth in this group. However, the mechanisms mediating this effect still needs to be elucidated.

Conclusion: Paternal sub-optimal nutrition programs the female offspring mammary gland development and breast cancer risk. Whether this increase in cancer risk is due to local mammary tissue changes or whether systemic changes play a role remains to be investigated. It also remains to be determined whether epigenetic changes in paternal sperm are functionally linked to changes in mammary gland development and cancer risk.

Citation Format: Raquel Santana, Elissa Carney, Hong Cao, Johan Clarke, M. Idalia Cruz, Lu Jin, Yi Fu, Zuolin Cheng, Joseph (Yue) Wang, Sonia de Assis. Paternal sub-optimal nutrition leads to programming of daughters' breast cancer risk in a mouse model [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2017; 2017 Apr 1-5; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2017;77(13 Suppl):Abstract nr 1257. doi:10.1158/1538-7445.AM2017-1257

Effects of In Utero Exposure to Ethinyl Estradiol on Tamoxifen Resistance and Breast Cancer Recurrence in a Preclinical Model

Background

Responses to endocrine therapies vary among patients with estrogen receptor (ER+) breast cancer. We studied whether in utero exposure to endocrine-disrupting compounds might explain these variations.

Methods

We describe a novel ER+ breast cancer model to study de novo and acquired tamoxifen (TAM) resistance. Pregnant Sprague Dawley rats were exposed to 0 or 0.1 ppm ethinyl estradiol (EE2), and the response of 9,12-dimethylbenz[a]anthracene (DMBA)-induced mammary tumors to 15 mg/kg TAM, with (n = 17 tumors in the controls and n = 20 tumors in EE2 offspring) or without 1.2 g/kg valproic acid and 5 mg/kg hydralazine (n = 24 tumors in the controls and n = 32 tumors in EE2 offspring) in the female offspring, was assessed. One-sided Chi2 tests were used to calculate P values. Comparisons of differentially expressed genes between mammary tumors in in utero EE2-exposed and control rats, and between anti-estrogen-resistant LCC9 and -sensitive LCC1 human breast cancer cells, were also performed.

Results

In our preclinical model, 54.2% of mammary tumors in the control rats exhibited a complete response to TAM, of which 23.1% acquired resistance with continued anti-estrogen treatment and recurred. Mammary tumors in the EE2 offspring were statistically significantly less likely to respond to TAM (P = .047) and recur (P = .007). In the EE2 offspring, but not in controls, adding valproic acid and hydralazine to TAM prevented recurrence (P < .001). Three downregulated and hypermethylated genes (KLF4, LGALS3, MICB) and one upregulated gene (ETV4) were identified in EE2 tumors and LCC9 breast cancer cells, and valproic acid and hydralazine normalized the altered expression of all four genes.

Conclusions

Resistance to TAM may be preprogrammed by in utero exposure to high estrogen levels and mediated through reversible epigenetic alterations in genes associated with epithelial-mesenchymal transition and tumor immune responses.

Paternal overweight is associated with increased breast cancer risk in daughters in a mouse model

While many studies have shown that maternal weight and nutrition in pregnancy affects offspring's breast cancer risk, no studies have investigated the impact of paternal body weight on daughters' risk of this disease. Here, we show that diet-induced paternal overweight around the time of conception can epigenetically reprogram father's germ-line and modulate their daughters' birth weight and likelihood of developing breast cancer, using a mouse model. Increased body weight was associated with changes in the miRNA expression profile in paternal sperm. Daughters of overweight fathers had higher rates of carcinogen-induced mammary tumors which were associated with delayed mammary gland development and alterations in mammary miRNA expression. The hypoxia signaling pathway, targeted by miRNAs down-regulated in daughters of overweight fathers, was activated in their mammary tissues and tumors. This study provides evidence that paternal peri-conceptional body weight may affect daughters' mammary development and breast cancer risk and warrants further studies in other animal models and humans.

Hydroxychloroquine inhibits autophagy to potentiate antiestrogen responsiveness in ER+ breast cancer

PURPOSE

Estrogen receptor-α (ERα)-targeted therapies including tamoxifen (TAM) or Faslodex (ICI) are used to treat ER(+) breast cancers. Up to 50% of tumors will acquire resistance to these interventions. Autophagy has been implicated as a major driver of antiestrogen resistance. We have explored the ability of hydroxychloroquine (HCQ), which inhibits autophagy, to affect antiestrogen responsiveness.

EXPERIMENTAL DESIGN

TAM-resistant MCF7-RR and ICI-resistant/TAM cross-resistant LCC9 ER(+) breast cancer cells were injected into mammary fat pads of female athymic mice and treated with TAM and/or ICI in combination with oral low-dose HCQ.

RESULTS

We show that HCQ can increase antiestrogen responsiveness in MCF7-RR and LCC9 cells and tumors, likely through the inhibition of autophagy. However, the combination of ICI+HCQ was less effective than HCQ alone in vivo, unlike the TAM+HCQ combination. Antiestrogen treatment stimulated angiogenesis in tumors but did not prevent HCQ effectiveness. The lower efficacy of ICI+HCQ was associated with ICI effects on cell-mediated immunity within the tumor microenvironment. The mouse chemokine KC (CXCL1) and IFNγ were differentially regulated by both TAM and ICI treatments, suggesting a possible effect on macrophage development/activity. Consistent with these observations, TAM+HCQ treatment increased tumor CD68(+) cells infiltration, whereas ICI and ICI+HCQ reduced peripheral tumor macrophage content. Moreover, macrophage elimination of breast cancer target cells in vitro was reduced following exposure to ICI.

CONCLUSION

HCQ restores antiestrogen sensitivity to resistant tumors. Moreover, the beneficial combination of TAM+HCQ suggests a positive outcome for ongoing neoadjuvant clinical trials using this combination for the treatment of ER(+) ductal carcinoma in situ lesions.

High-fat or ethinyl-oestradiol intake during pregnancy increases mammary cancer risk in several generations of offspring

Maternal exposures to environmental factors during pregnancy influence the risk of many chronic adult-onset diseases in the offspring. Here we investigate whether feeding pregnant rats a high-fat (HF)- or ethinyl-oestradiol (EE2)-supplemented diet affects carcinogen-induced mammary cancer risk in daughters, granddaughters and great-granddaughters. We show that mammary tumourigenesis is higher in daughters and granddaughters of HF rat dams and in daughters and great-granddaughters of EE2 rat dams. Outcross experiments suggest that the increase in mammary cancer risk is transmitted to HF granddaughters equally through the female or male germ lines, but it is only transmitted to EE2 granddaughters through the female germ line. The effects of maternal EE2 exposure on offspring's mammary cancer risk are associated with changes in the DNA methylation machinery and methylation patterns in mammary tissue of all three EE2 generations. We conclude that dietary and oestrogenic exposures in pregnancy increase breast cancer risk in multiple generations of offspring, possibly through epigenetic means.

Environmental factors can influence one's susceptibility to cancer, but it is not clear whether such an influence extends beyond the directly exposed generations. Here, feeding pregnant rats with a high-fat diet or a hormone derivative, the authors observe increased breast cancer risk in up to three subsequent generations.

Abstract 5442: MicroRNAs may mediate multigenerational epigenetic inheritance of mammary cancer risk caused by maternal exposure to high-fat diet during pregnancy

Maternal dietary exposure to high-fat (HF) during pregnancy increases mammary cancer risk in daughters and granddaughters. It also causes persistent changes in mammary gland morphology in these two HF generations. Our results further show that an increase in mammary cancer risk can be transmitted to HF granddaughters either through the female or male germlines. Disease traits resulting from environmental in utero exposures can be transmitted through multiple generations by epigenetic means. Here, we investigated whether misregulation of expression of specific miRNAs may be involved in mediating the effects of maternal HF exposure during pregnancy on mammary cancer risk in multiple generations of offspring. Pregnant Sprague-Dawley rats were fed isocaloric control or HF diets (fat source: corn oil) throughout pregnancy. The effects on mammary cancer risk in daughters and granddaughters were examined and reported earlier. Total RNA was obtained from mammary glands on postnatal day (PND) 50 from control and HF daughters (F1 generation) and granddaughters (F2 generation). MicroRNA levels were measured using Applied Biosystems TaqManR Array Rodent MicroRNA Card Set v2.0. mRNA expression levels were assessed using q-PCR. Maternal HF exposure during pregnancy increased carcinogen-induced mammary tumorigenesis in both daughters and granddaughters (p=0.049 and p=0.028, respectively). Higher mammary tumor incidence was also observed in the F2 generation even if only one parent had been exposed to HF diet in utero. Fifty one miRNAs were significantly down-regulated on PND50 in mammary glands of HF daughters compared to controls. From these, five miRNAs were also down-regulated in mammary tissue of HF granddaughters compared to controls: let-7c, miR-7a, miR-17, miR-299 and miR-770. Down-regulation of miR-7a and miR-770 was transmitted only through the male germline; i.e., they were expressed at a significantly lower level in F2 daughters of in utero HF exposed fathers, but not HF mothers. Mammary mRNA levels of the polycomb gene, EZH2, a target of let-7c, were up-regulated in both HF daughters and granddaughters compared to controls (p=0.014). Our findings indicate that maternal exposure to HF diet during pregnancy causes a persistent suppression of some miRNAs in the offspring's mammary gland that is transmitted to next generation. The down-regulation of some of these miRNAs was transmitted through the male germline. Moreover, up-regulation of EZH2 transcript, a target gene for let-7c, in mammary tissue of HF daughters and granddaughters, confirms the functional consequence of suppression of this miRNA. Additional studies are needed to elucidate the consequences of suppression of other miRNAs uncovered in this study, and whether they are causally related to increased mammary cancer risk.

Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 103rd Annual Meeting of the American Association for Cancer Research; 2012 Mar 31-Apr 4; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2012;72(8 Suppl):Abstract nr 5442. doi:1538-7445.AM2012-5442

Changes in mammary gland morphology and breast cancer risk in rats

Studies in rodent models of breast cancer show that exposures to dietary/hormonal factors during the in utero and pubertal periods, when the mammary gland undergoes extensive modeling and re-modeling, alter susceptibility to carcinogen-induced mammary tumors. Similar findings have been described in humans: for example, high birthweight increases later risk of developing breast cancer, and dietary intake of soy during childhood decreases breast cancer risk. It is thought that these prenatal and postnatal dietary modifications induce persistent morphological changes in the mammary gland that in turn modify breast cancer risk later in life. These morphological changes likely reflect epigenetic modifications, such as changes in DNA methylation, histones and miRNA expression that then affect gene transcription . In this article we describe how changes in mammary gland morphology can predict mammary cancer risk in rats. Our protocol specifically describes how to dissect and remove the rat abdominal mammary gland and how to prepare mammary gland whole mounts. It also describes how to analyze mammary gland morphology according to three end-points (number of terminal end buds, epithelial elongation and differentiation) and to use the data to predict risk of developing mammary cancer.

A Substance P Antagonist Increases Brain Intracellular Free Magnesium Concentration after Diffuse Traumatic Brain Injury in Rats

OBJECTIVE

Magnesium (Mg) deficiency has been shown to increase substance P release and induce a pro-inflammatory response that can be attenuated with the administration of a substance P-antagonist. Neurogenic inflammation has also been implicated in traumatic brain injury (TBI), a condition where brain intracellular free magnesium (Mg(f)) decline is known to occur and has been correlated with functional outcome. We therefore examined whether a substance P antagonist restores brain intracellular free magnesium concentration following TBI.

METHODS

Male, adult Sprague-Dawley rats were injured using the Cernak impact acceleration model of diffuse TBI. At 30 min after injury, animals were administered either 0.25 mg/kg i.v. n-acetyl tryptophan or equal volume saline. Prior to and 4 h after induction of injury, phosphorus magnetic resonance spectra were acquired using a 7-tesla magnet interfaced with a Bruker console. Mg(f) was calculated from the chemical shift of the beta ATP. Before injury, Mg(f) was 0.51 +/- 0.05 mM (SEM).

RESULTS

By 4 hr after injury, Mg(f) had significantly declined to 0.27 +/- 0.02 mM in saline treated rats. In contrast, rats treated with n-acetyl tryptophan had a Mg(f) of 0.47 +/- 0.06 mM at 4 h after injury, which was not significantly different from preinjury values. There were no significant differences in pH between the treatment groups.

CONCLUSION

It seems that any beneficial effect of a substance P antagonist on functional outcome following TBI may be related to improvement in brain Mg homeostasis induced by the compound.