Jacqueline Parada

Abstract 2264: Anticancer effect of gedunin against pancreatic cancer cell lines.

Pancreatic cancer is 4 th leading cause of cancer related deaths. It is highly aggressive and resistant to most chemotherapeutic treatments. Unfortunately, treatment options for pancreatic cancer are limited, leading to a poor prognosis and high mortality rates. The development of resistance to chemotherapeutic agents is a major obstacle to the treatment of cancer. Current therapies often target a single oncogenic protein; due to genetic plasticity/instability, pancreatic cancer cells are able to circumvent the drug effects. This type of resistance may be avoided, if multiple cancer signaling pathways are targeted simultaneously with a single therapeutic agent. Thus, novel therapeutic approaches are needed to treat pancreatic cancer. Natural products have been shown to play an important role as anticancer agents. Neem (Azadirachta indica) tree is known for its medicinal values. All parts of the tree including leaves, flowers, seeds, fruits, roots and bark are known to possess a wide range of medicinal properties. Neem leaf extracts, which are non-toxic and non-mutagenic, have been shown to possess anti-inflammatory, antioxidant, anticarcinogenic, and potent immuno-stimulant activities in many cancer cells. We have demonstrated that ethanolic fraction of neem leaves has potent anticancer effect against mammary carcinogenesis. Gedunin is a tetraterpinoid isolated from neem leaves. Gedunin has been established as a potent inhibitor of heat shock protein 90 (Hsp90). The family of 90 kDa heat shock proteins (Hsp90) has emerged as a novel drug target that mediates multiple signaling nodes to combat cancer. In the current study, we investigated the anticancer effect of gedunin against pancreatic cancer cell lines. Our preliminary data clearly demonstrates that gedunin inhibits the growth of pancreatic cancer cell lines. We also explored the molecular mechanism underlying the anti-cancer effect of gedunin on pancreatic cancer cells. As expected gedunin decreased the expression of Hsp90. Gedunin treatment also decreased the phosphorylation of mTOR, 4EBP. Furthermore, gedunin also induced autophagy and apoptosis simultaneously by regulating key factors involved in these processes like LC3B, WIPI-1, VMP-1, pJNK, cleavage of caspases and PARP. Overall, our preliminary results strongly suggest that gedunin could be a potential anticancer compound for the treatment of pancreatic cancer. Citation Format: Thiyagarajan Boopalan, Anirudh Chaudhary, Sowmiya Murali, Arunkumar Arumugam, Rebecca Lopez, Sushmita Nandy, Christina Gutierrez, Jacqueline Parada, Pamela Agullo, Rajkumar Lakshmanaswamy. Anticancer effect of gedunin against pancreatic cancer cell lines. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2264. doi:10.1158/1538-7445.AM2013-2264

Abstract 2573: Serum proteomic analysis of early pregnancy-induced protection against breast cancer.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC The incidence of breast cancer is very high in western countries and is increasing rapidly in the third world. It is the most common cancer in women worldwide. Since it is difficult to defeat breast cancer after it has occurred, finding new strategies to delay or prevent the development of breast cancer has been an important area for clinical and experimental investigations. Women who undergo a full- term pregnancy before the age of 20, with or without lactation, have about one half the risk of developing breast cancer compared to women who undergo their first pregnancy after the age of 35 or women who have never undergone a full term pregnancy. This universal protective effect of pregnancy serves as a major clue and starting point in the search for new strategies and novel biomarkers related to the prevention of breast cancer. For the current study, women were recruited into one of the following categories; 1) had their first child ≤ 25 years of age [early parous], 2) had their first child ≥ 35 years of age [late parous], and 3) a control group of women the same age as those in groups 1 and 2 but who have never given birth [nulli parous]. Blood was collected these women and serum was separated. A high throughput proteomic analysis was performed with the samples collected. Briefly, protein was extracted from the samples and conjugated to a phosphoexplorer antibody array, detected with Cy3- streptavidin, and scanned with a microarray scanner. Using bioinformatic software, significantly differentially expressed proteins of interest have been found in late parous and nulli parous samples when compared to the early parous samples. We have identified the top 20 differentially expressed total (LIMK1, p53, Paxillin, Ret, Tyrosine hydroxylase) and phosphorylated (p14-3-3 theta, p14-3-3 zeta, pCav1, pCD3Z, pDok-1) proteins between the different groups. Several proteins identified using the phosphoexplorer antibody arrays have been validated using Western blots. Overall, this study focuses on the analysis of human breast tissue and serum to gain a deeper understanding of how early parity confers protection against breast cancer. Citation Format: Christina Gutierrez, Arunkumar Arumugam, Rebecca Lopez, Thiyagarajan Boopalan, Sushmita Nandy, Pamela Agullo, Jacqueline Parada, Susan Love, Rajkumar Lakshmanaswamy. Serum proteomic analysis of early pregnancy-induced protection against breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2573. doi:10.1158/1538-7445.AM2013-2573

Abstract 5011: Molecular alterations in mammary stem cells in response to pregnancy or short-term estradiol treatment leads to the reduced risk of breast cancer.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC Breast cancer is the most common cancer in women worldwide. Early pregnancy is the only known natural phenomenon that reduces the risk of breast cancer. Rodents like rats and mice that undergo a full term pregnancy also have a greatly reduced susceptibility to chemical carcinogen induced mammary carcinogenesis compared to nulliparous rats and mice. Earlier we have demonstrated that short-term treatment with pregnancy levels of estradiol is highly effective in conferring protection against mammary carcinogenesis. Carcinogenesis is a multistep process which includes initiation, promotion and progression. In the current study our objective was to determine the molecular mechanisms underlying the protective effect conferred by parity and short-term treatment with pregnancy levels of estradiol against mammary carcinogenesis. We mainly focused on the differences in mammary stem cells between virgin, parous and short-term estradiol treated groups. Virgin Lewis rats were implanted with Alzet mini pumps releasing 1 microgram of estradiol/day at 7 weeks of age. The Alzet pumps were removed 3 weeks later. Rats were mated between 6-7 weeks of age. The pups and mother were weaned after three weeks of lactation. Six weeks after weaning or withdrawal of hormone treatment (16 weeks of age), the rats were treated with 50 mg/kg of N-methyl-N-nitorosurea (MNU). Rats from all the three groups were euthanized at different timepoints. Mammary gland was surgically removed and mammary stem cells were sorted using flow cytometry. Cells that were positive for aldehyde dehydrogenase, CD44 and low or negative for CD24 were sorted and used for molecular analysis. Using stem cell signaling PCR arrays we have attempted to identify differences in gene expression among mammary stem cells obtained from the three groups of animals. We observed clear differences in expression of fibroblast growth factor receptos (FGFRs), notch, smads, and transcription factors between virgin mammary stem cells in comparison to parous and short-term estratiol treated mammary stem cells. These findings are currently being validated using quantitative RTPCR and immunoblotting. The results obtained will be presented. The current data indicates that there are molecular differences in the mammary stem cells between animals that are susceptible to mammary carcinogenesis compared to animals that are protected against mammary carcinogenesis. Citation Format: Sushmita B. Nandy, Arunkumar Arumugam, Jacqueline Parada, Rebecca Lopez, Thiyagarajan Boopalan, Christina Gutierrez, Pamela Agullo, Rajkumar Lakshmanaswamy. Molecular alterations in mammary stem cells in response to pregnancy or short-term estradiol treatment leads to the reduced risk of breast cancer. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 5011. doi:10.1158/1538-7445.AM2013-5011

Abstract 199: Short-term treatment with pregnancy levels of estradiol prevents breast cancer by delaying promotion and progression.

Proceedings: AACR 104th Annual Meeting 2013; Apr 6-10, 2013; Washington, DC A full term pregnancy early in life reduces the risk of breast cancer in women. A similar phenomenon is also observed in rats and mice. Recent findings indicate that estradiol alone replacement therapy in postmenopausal women also reduces the risk of breast cancer. We have earlier demonstrated that short-term treatment with pregnancy levels of estradiol (STET) is very effective in preventing mammary carcinogenesis. In the current study our objective was to determine whether STET conferred protection against mammary carcinogenesis by blocking initiation or promotion. Rats were injected with N-methyl-N-nitrosourea at 7 weeks of age and divided into 2 groups. One group (n=30) did not receive any further treatment and served as controls and the second group (n=30) of rats was treated with 1 microgram of estradiol per day for 3 weeks using a subcutaneous implant of Alzet osmotic mini pump. A subset (n=5) were terminated 3 and 6 months post carcinogen treatment. The other animals were terminated 9 months post carcinogen treatment. Mammary gland wholemounts were prepared at each termination timepoint and examined for the presence of latent microscopic mammary cancers (LMMC). In another experiment we surgically isolated LMMC and transplanted them back into a host from the same group (control to control or STET to STET) or to a host from the other group (control to STET or STET to control). Short-term treatment with pregnancy levels of estradiol drastically reduced the incidence of overt mammary cancers. Although a significant reduction of overt cancers was observed in the pregnancy levels of estradiol treated groups, there was no difference in the incidence of LMMC between the estradiol treated and the controls. LMMC were isolated from the mammary glands. Breast cancer and estrogen receptor signaling specific microarrays were performed to find differences in gene expression in LMMC between the controls and STET groups. We were able to identify clear differences in gene expression in LMMC between the two groups. Genes involved in angiogenesis (Thbs1, Vegfa), apoptosis (Bad, Bcl2) and cell cycle (Ccnd1, Cdk2) were differentially expressed. Further several transcription factors (Esr1, Esr2, Gata3, Rb1) were also differentially expressed in LMMC between the controls and STET groups. The transplantation experiment indicated that the progression of LMMC was dependent on the systemic environment it is exposed to. The LMMC derived from control were not able to progress further to make overt cancers when transplanted STET hosts, while the LMMC derived from STET were able to progress to overt cancers when transplanted to control hosts. These findings demonstrate that STET confers protection against mammary cancer development by blocking promotion and progression of transformed cells. Understanding this phenomenon shall assist in the design of novel prevention and therapeutic strategies against breast cancer. Citation Format: Arunkumar Arumugam, Maricarmen Stout, Cathy Tsin, Amar Bhat, Taylor Yong, Sushmita Nandy, Christina Gutierrez, Rebecca Lopez, Thiyagarajan Boopalan, Jacqueline Parada, Rajkumar Lakshmanaswamy. Short-term treatment with pregnancy levels of estradiol prevents breast cancer by delaying promotion and progression. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 199. doi:10.1158/1538-7445.AM2013-199

Abstract 1862: Prediabetic and diabetic levels of glucose enhance the proliferation of normal and malignant breast epithelial cells via increased leptin signaling and activation of mTOR.

Introduction: It is now well-appreciated that diabetes and obesity increase the risk of breast cancer in women and result in worse disease progression once breast cancer is diagnosed. Moreover, breast cancer rates are increasing worldwide and breast cancer is now the most common malignancy in women across the globe. However, the exact etiology behind increased breast cancer incidence and severity observed in overweight/diabetic patients remains to be fully elucidated. Many experts now concede that diabetes/obesity have reached epidemic proportions globally. Therefore, it is particularly important to understand how these two chronic diseases promote and enhance the development of breast cancer, as well as, other common forms of cancer. Methods: A normal breast epithelial cell line (MCF10A) and two malignant breast epithelial cell lines (MCF7, MB-MDA-231) were treated with three different glucose concentrations: normal (5.5mM), prediabetic (10mM), and diabetic (25mM). The effects of increasing glucose on cell proliferation and intracellular signaling were assessed at 24hr, 48hr, and 72hr. MTS assay was used to monitor cell proliferation and Annexin V/propidium iodide staining was used to monitor apoptosis/cell death. Intracellular signaling intermediates were assessed via Western blot. Results: Prediabetic and diabetic glucose enhanced proliferation of both normal and malignant breast cells. Normal cells exhibited the greatest increase in cell growth. No major changes in apoptosis or cell death were observed for either normal or malignant cells. The three most abundant leptin receptor isoforms were significantly upregulated with increasing glucose in both normal and malignant cells. Likewise, GRB2, PTP1B, and SOCS3 were significantly upregulated with increasing glucose. Transient increases in JAK2 phosphorylation also occurred in all three cell lines with increasing glucose. In contrast, STAT3 phosphorylation was not significantly altered in malignant cells but was transiently increased in normal cells with increasing glucose. Transient but significant increases in mTOR phosphorylation were also observed for all three cell lines with increasing glucose and this generally corresponded with transient suppression of AMPK phosphorylation. Conclusions: To our knowledge, we demonstrate for the first time that in the absence of hyperleptinemia or hyperinsulinemia increasing glucose levels can, by themselves, directly impact leptin-receptor signaling in breast epithelial cells. Our results implicate leptin-receptor signaling in the pathogenesis of hyperglycemia in both normal and malignant cells. Components of this pathway may be useful targets for the prevention and treatment of diabetes, obesity, and ultimately breast cancer. Citation Format: Rebecca Lopez, Pamela Agullo, Arunkumar Arumugam, Riya Joseph, Kanika Monga, Sushmita Nandy, Thiyagarajan Boopalan, Christina Gutierrez, Jacqueline Parada, Rajkumar Lakshmanaswamy. Prediabetic and diabetic levels of glucose enhance the proliferation of normal and malignant breast epithelial cells via increased leptin signaling and activation of mTOR. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 1862. doi:10.1158/1538-7445.AM2013-1862

Abstract 571: Prevention of breast cancer by delaying promotion and progression

A full term pregnancy early in life reduces the risk of breast cancer in women. A similar phenomenon is also observed in rats and mice. Short-term treatment with pregnancy levels of estradiol is also highly effective in preventing mammary carcinogenesis. In the current study our objective was to determine whether short-term treatment with pregnancy levels of estradiol conferred protection against mammary carcinogenesis by blocking initiation or promotion. Rats were injected with N-methyl-N-nitrosourea at 7 weeks of age and treated with 20 µg, 100 µg, 200 µg or 30 mg of estradiol in silastic capsules for 3-weeks. The experiments were terminated 9 months post carcinogen treatment. Mammary gland wholemounts were prepared at termination and examined for the presence of latent microscopic mammary cancers. Short-term treatment with pregnancy levels of estradiol drastically reduced the incidence of overt mammary cancers. 100 µg, 200 µg and 30 mg doses of estradiol resulted in levels of estradiol equivalent to pregnancy level and were effective in preventing overt mammary cancer incidence compared to control or 20 µg estradiol treatment which did not result in pregnancy levels of estradiol in the circulation. Although a significant reduction of overt cancers was observed in the pregnancy levels of estradiol treated groups, there was no difference in the incidence of microscopic mammary cancers between the estradiol treated and the controls. Proliferation of microscopic mammary cancers was examined using immunohistochemistry for cyclin D1 expression. Proliferation in the microscopic mammary cancers of the protected groups was significantly lower (∼ 2-3 fold) than the microscopic mammary cancers in the unprotected groups. These findings clearly demonstrate that short-term treatment with pregnancy levels of estradiol confers protection against mammary cancer development by blocking promotion and progression of carcinogen initiated cells. 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 571. doi:1538-7445.AM2012-571

Abstract 1318: Progesterone promotes estrogen induced mammary carcinogenesis through activation of RANKL

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Ovarian hormones estrogen and progesterone play a vital role in normal development and function of breast tissue. Over exposure to ovarian hormones, especially estrogens and progesterone increase the risk of breast cancer. Epidemiological and experimental studies argue that estrogens are central to its etiology. It has been demonstrated that ovary intact ACI rats given estrogen induced high incidence of mammary cancers while ovariectomized rats given the same dose of estrogen for the same length of time did not induce mammary cancers. Recently, we demonstrated that ovariectomized ACI rats given estrogen plus progesterone had a high incidence of mammary cancer. Hence, it is essential to understand the possible role of progesterone in mammary carcinogenesis. Our goal was to determine the mechanism by which progesterone promotes estrogen induced mammary carcinogenesis in ACI rats. To achieve our goal, we designed the following experiment. Ovary intact (7 week old) and ovariectomized (at 5 weeks; treatment starting at 7 weeks) rats were used in this study. The groups (n=30) tested were as follows: 1) ovary intact control (no hormone treatment); 2) ovary intact rats given 30 mg estradiol; 3) ovary intact rats given 30 mg estradiol plus 30 mg mifepristone(progesterone antagonist); 4) ovary intact rats given 30 mg progesterone; 5) ovariectomized control (no hormone treatment); 6) ovariectomized rats given 30 mg estrogen; and 7) ovariectomized rats given 30 mg estradiol plus 30 mg progesterone. Mammary glands were surgically excised and snap frozen in liquid nitrogen and stored at -80°C from a subset (n=4) animals after four weeks of treatment. Mammary carcinogenesis was followed for nine months in rest of the animals. Estradiol induced mammary cancers in ovary intact rats and not in ovariectomized rats. Treatment with progesterone plus estradiol to ovariectomized rats induced high incidence of mammary cancer. Mifepristone treatment inhibited estradiol induced mammary carcinogenesis in ovary intact rats. Pathway focused microarray analysis of mammary glands from the rats of different groups and treatment indicated alterations in apoptosis and PI3K pathways. Estrogen plus progesterone treatment down regulated apoptotic genes such as Apaf1, Bad, Bax, Bid, Casp9 and up regulated Nfkb1, Nfkbia and Tollip when compared with estrogen alone treatment in ovariectomized rats. RANK and RANKL expression was significantly increased by estradiol plus progesterone, than estradiol alone or ovariectomized controls. We have observed that progesterone mediates estrogen induced mammary carcinogenesis through RANKL and RANK both at transcriptional and translational levels. Our results clearly demonstrate that progesterone promotes activation of NF-κB by activation of RANKL in estrogen induced carcinogenesis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1318. doi:10.1158/1538-7445.AM2011-1318

Abstract 4238: Azadirachta indica leaf extract inhibits mammary carcinogenesis by altering key signaling pathways

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL It is estimated that 20-60% of cancer patients utilize some form of alternative medicine. Plant products play a major role in complimentary medicine. Azadirachta indica tree commonly known as neem has been known for centuries to possess medicinal properties like immunomodulatory, anti-inflammatory, antimutagenic, and anticarcinogenic. We have previously shown that A. indica leaf extract has potent anticarcinogenic capabilities in N-methyl-N-nitrosurea (MNU)-induced mammary cancer model. The aim of our study is to explore the molecular pathways through which A. indica induces mammary tumor regression. Seven week old female Lewis rats were administered MNU. On the appearance of the first palpable tumor the rats were divided into groups receiving different doses of ethanolic A. indica leaf extract (ALE): group 1 control, no treatment; group 2 0.125mg/day; group 3: 0.250mg/day; group 4: 0.500mg/day; group 5: 1mg/day. Treatment was daily for 4 weeks intraperitoneally. The animals were euthanized 12 weeks after the termination of treatment and mammary tumor tissue samples were snap frozen and also fixed in formalin. To analyze key gene expression changes we performed pathway focused PCR microarrays for apoptosis, PI3-Kinase, and angiogenesis signaling pathways. Our results show that ALE induces tumor regression, decreases tumor volume, and inhibits mammary tumor growth by altering specific molecular pathways, linked to the stimulation (Bax, caspases) and inhibition (Bcl-2, CDC42)of apoptosis, up-regulation of tumor suppressor genes (PTEN), down-regulation of proto-oncogene Jun, and inhibition of cell survival (Foxg1, BTK, Akt). ALE treatment down-regulated genes fundamental to migration, adhesion and proliferation of tumor cells (EFNA1, Hif1a). Timp1 (TIMP family matrix metalloproteinase inhibitor) and cyclin D1 expression exhibited a clear dose response. Our data indicates that ALE treatment inhibits mammary tumor development by altering apoptosis, PI3-Kinase and angiogenesis pathways. In conclusion, ALE could be used as a novel complimentary agent that offers anticarcinogenic effects against breast cancer and could also be used along with the current standard treatment options. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 4238. doi:10.1158/1538-7445.AM2011-4238

Abstract 863: Molecular alterations associated with the protective effect of short-term estradiol treatment against mammary carcinogenesis

Proceedings: AACR 102nd Annual Meeting 2011‐‐ Apr 2‐6, 2011; Orlando, FL Early childbirth is the only known physiological factor to have a protective effect against the development of breast cancer. Rats that have been exposed to carcinogens before or after a full-term pregnancy are protected from mammary carcinogenesis. Hormonal prevention strategies have used exogenous hormonal treatment to mimic the protective effect of early full-term pregnancy against breast cancer. We have previously demonstrated that short-term administration of pregnancy levels of estradiol alone or in combination with progesterone confers long-term protection against mammary carcinogenesis. In the present study our aim was to define a gene and protein expression profile that would serve as a signature for assessing the efficacy of the protective hormone treatment. Nine week old female Lewis rats were divided into the three following groups (n=15): (i) control, (ii) 10µg estradiol (non-protective dose), and (iii) 200µg estradiol (protective dose). Each treatment was given in the form of silastic capsule and continued for the length of gestation (3 weeks) in rats. At the end of the treatment, the silastic capsule was removed. The rats were terminated 8 and 16 weeks following removal of the hormone treatment. Mammary glands were removed, immediately snap frozen. Our data indicate that several genes like igfbp5, Rbp2, Egr1, igfbp2, Cd47, Prkra, Perp, Tdag, Spint2 and Hat1 involved in apoptosis, DNA repair and growth inhibition are upregulated in the mammary glands of rats that received pregnancy levels of estradiol treatment compared to the rats that received non-pregnancy levels of estradiol and untreated controls. By contrast, there were consistent decreases in genes involved in growth regulation (II18, THBS, Tshr), angiogenesis (MMp11), anti-apoptosis (Mt1a) and cell cycle regulation (Cdk2,Cdk4) in the mammary glands of pregnancy level estradiol treated rats compared to the non pregnancy level estradiol treated rats and untreated controls. These alterations were consistent at both time points indicating that these changes are constitutive. Furthermore, estrogen receptor pathway analysis revealed that ER-α is downregulated following administration of 10µg and 200µg estradriol. ER-β is upregulated in the 200 µg estradiol treatment and downregulated in the 10 µg estradiol treatment. In conclusion, short term treatment with pregnancy levels of estradiol leads to persistent down regulation of genes involved in, cell cycle, growth promotion, anti-apoptosis, oncogenesis, angiogenesis and also alters the balance between ER-α and ER-β. In contrast, the same protective treatment persistently up-regulated genes associated with, apoptosis, DNA repair and growth inhibition. The results obtained offer key insights into the protective effect imparted by early pregnancy and shall lead to the design of novel prevention strategies against breast cancer. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 863. doi:10.1158/1538-7445.AM2011-863

Abstract 1317: Estradiol and progesterone promotes breast tumor growth through induction of AKT/mTOR pathway and inhibition of apoptosis

Breast cancer development is accomplished by unbalanced regulation of several signaling pathways. Studies indentifying potential targets for mammary cancer treatment and prevention are vital. Copenhagen strain of rat is a well known animal model which is resistant to carcinogen-induced mammary carcinogenesis. In our laboratory, we were able to induce a very high incidence of mammary cancers in these rats using combination of carcinogen N-methyl-N-nitrosourea (MNU), followed by estradiol and progesterone treatment. We have demonstrated that the resistance to mammary carcinogenesis in these rats is not due to inhibition of initiation but due to reduced hormone promotional environment and we further extend our research to investigate the molecular mechanisms involved behind this hormone-induced promotion. In the present study, we exposed 7 week old female Copenhagen rats to N-methyl-N-nitrosourea (MNU; 50mg/kg body weight). Immediately after MNU treatment the rats were divided into the following groups: 1) Control 2) 17β-estradiol (30mg) 3) progesterone (30mg) and 4) 17β-estradiol (30mg) plus progesterone (30mg). All hormone treatments were administered via individual silastic pellets for a period of 9 months post carcinogen treatment. At the end of the treatment period rat mammary tumors were excised and used for molecular analysis. Quantitative RT-PCR and western blot analysis showed that ovarian hormones treatment triggered the AKT/mTOR pathway along with increased cell cycle progression. Intra cellular MAPK signaling was increased through activation of AKT/PI3K pathway. Hormone administration decreased the levels of caspase-3, caspase-8 and caspase-9. Together, our result indicates that hormone treatment induces mammary tumor growth through activation of AKT/PI3K/mTOR pathways and simultaneously inhibiting apoptosis. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 102nd Annual Meeting of the American Association for Cancer Research; 2011 Apr 2-6; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2011;71(8 Suppl):Abstract nr 1317. doi:10.1158/1538-7445.AM2011-1317