Stéphanie Jean

Deoxypodophyllotoxin Isolated from Juniperus communis Induces Apoptosis in Breast Cancer Cells

The study of anticancer properties from natural products has regained popularity as natural molecules provide a high diversity of chemical structures with specific biological and medicinal activity. Based on a documented library of the most common medicinal plants used by the indigenous people of North America, we screened and isolated compounds with anti-breast cancer properties from Juniperus communis (common Juniper). Using bioassay-guided fractionation of a crude plant extract, we identified the diterpene isocupressic acid and the aryltetralin lignan deoxypodophyllotoxin (DPT) as potent inducers of caspase-dependent programmed cell death (apoptosis) in malignant MB231 breast cancer cells. Further elucidation revealed that DPT, in contrast to isocupressic acid, also concomitantly inhibited cell survival pathways mediated by the MAPK/ERK and NFκB signaling pathways within hours of treatment. Our findings emphasize the potential and importance of natural product screening for new chemical entities with novel anticancer activities. Natural products research complemented with the wealth of information available through the ethnobotanical and ethnopharmacological knowledge of the indigenous peoples of North America can provide new candidate entities with desirable bioactivities to develop new cancer therapies.

Adiponectin influences progesterone production from MA-10 Leydig cells in a dose-dependent manner

Obesity in men is associated with lower testosterone levels, related to reduced sperm concentration and the development of various diseases with aging. Hormones produced by the adipose tissue may have influences on both metabolism and reproductive function. Among them, the production and secretion of adiponectin is inversely correlated to total body fat. Adiponectin receptors (AdipoR1 and AdipoR2) have been found to be expressed in testicular Leydig cells (producing testosterone). Since StAR and Cyp11a1 are essential for testosterone synthesis and adiponectin has been shown to regulate StAR mRNA in swine granulosa cells, we hypothesized that adiponectin might also regulate these genes in Leydig cells. Our objective was to determine whether adiponectin regulates StAR and Cyp11a1 genes in Leydig cells and to better define its mechanisms of action. Methods used in the current study are qPCR for the mRNA levels, transfections for promoter activities, and enzyme-linked immunosorbent assay for the progesterone concentration. We have found that adiponectin cooperates with cAMP-dependent stimulation to activate StAR and Cyp11a1 mRNA expressions in a dose-dependent manner in MA-10 Leydig cells as demonstrated by transfection of a luciferase reporter plasmid. These results led to a significant increase in progesterone production from MA-10 cells. Thus, our data suggest that high doses of adiponectin typical of normal body weight may promote testosterone production from Leydig cells.

Mammaglobin 1 promotes breast cancer malignancy and confers sensitivity to anticancer drugs

Mammaglobin 1 (MGB1), a member of the secretoglobin family, is expressed in mammary epithelial tissues and is overexpressed in most mammary carcinomas. Despite the extensive research correlating MGB1 expression profiles to breast cancer pathogenesis and disease outcome, the biological significance of MGB1 in cancer processes is still unclear. We have thus set out to conduct a functional evaluation of the molecular and cellular roles of MGB1 in breast cancer processes leading to disease progression. Using a series of breast cancer cell models with conditional MGB1 expression, we demonstrate that MGB1 promotes cancer cell malignant features. More specifically, loss of MGB1 expression resulted in a decrease of cell proliferation, soft agar spheroid formation, migration, and invasion capacities of breast cancer cells. Concomitantly, we also observed that MGB1 expression activates signaling pathways mediated by MAPK members (p38, JNK, and ERK), the focal adhesion kinase (FAK), matrix metalloproteinases (MMPs) and NFκB. Moreover, MGB1 regulates epithelial to mesenchymal (EMT) features and modulates Snail, Twist and ZEB1 expression levels. Interestingly, we also observed that expression of MGB1 confers breast cancer cell sensitivity to anticancer drug‐induced apoptosis. Together, our results support a role for MGB1 in tumor malignancy in exchange for chemosensitivity. These findings provide one of the first descriptive overview of the molecular and cellular roles of MGB1 in breast cancer processes and may offer new insight to the development of therapeutic and prognostic strategies in breast cancer patients.

Breast Cancer Malignant Processes are Regulated by Pax-5 Through the Disruption of FAK Signaling Pathways.

The study of genetic factors regulating breast cancer malignancy is a top priority to mitigate the morbidity and mortality associated with this disease. One of these factors, Pax-5, modulates cancer aggressiveness through the regulation of various components of the epithelial to mesenchymal transitioning (EMT) process. We have previously reported that Pax-5 expression profiles in cancer tissues inversely correlate with those of the Focal Adhesion Kinase (FAK), a potent activator of breast cancer malignancy. In this study, we set out to elucidate the molecular and regulatory relationship between Pax-5 and FAK in breast cancer processes. Interestingly, we found that Pax-5 mediated suppression of breast cancer cell migration is dependent of FAK activity. Our mechanistic examination revealed that Pax-5 inhibits FAK expression and activation. We also demonstrate that Pax-5 is a potent modulator of FAK repressors (p53 and miR-135b) and activator (NFκB) which results in the overall suppression of FAK-mediated signaling cascades. Altogether, our findings bring more insight to the molecular triggers regulating phenotypic transitioning process and signaling cascades leading to breast cancer progression.

Influence of the adipose derived hormone resistin on signal transducer and activator of transcription factors, steroidogenesis and proliferation of Leydig cells

Abstract Objective To explore whether resistin, an adipose derived hormone linked to insulin resistance, influence steroidogenic genes expressions and Leydig cells function or not. Methods Various Leydig cell lines were exposed to increasing doses of resistin with or without cAMP. Changes were monitored at the protein level for signal transducer and activator of transcription (STAT) factors and steroidogenic components, steroidogenic acute regulatory protein (STAR) and cholesterol side-chain cleavage enzyme (CYP11A1), for progesterone production and cell viability. Results Resistin had no effect on progesterone production, despite an increase in nuclear translocation of STAT1, STAT3 and STAT5 and unexpected synergy with cAMP in the synthesis of STAR and CYP11A1. In addition, exposure to normal levels of resistin (10 ng/mL) seemed to have beneficial effects on Leydig cell function, as it increased cells viability and proliferation. Conclusions Our results suggest that resistin may function as an endocrine mediator linking metabolism and male reproduction.

Dibenz[b,f]oxepin and Antimycobacterial Chalcone Constituents of Empetrum nigrum

Two new dibenz[b,f]oxepins, empetroxepins A and B (1 and 2), and seven known compounds (3-9) were isolated from an extract of the Canadian medicinal plant Empetrum nigrum that significantly inhibited the growth of Mycobacterium tuberculosis H37Ra. The structures of 1 and 2 were established through analysis of NMR and MS data. The antimycobacterial activity of the plant extract was attributed primarily to the presence of two chalcone derivatives (6 and 7) that exhibited selective antimycobacterial activity (IC50 values of 23.8 and 32.8 μM, respectively) in comparison to mammalian (HEK 293) cells (IC50 values of 109 and 249 μM, respectively).

Abstract 2266: The characterization of anti-breast cancer compounds isolated from the Juniperus communis.

Breast cancer is the most common form of cancer in the female population worldwide where approximately 30% of these women will succumb to their disease. The identification of novel, efficacious and safe anticancer drugs is thus essential to mitigate the morbidity and mortality associated with this disease. More recently, the study of anticancer properties from natural products has regained popularity as natural entities provide more biodiversity of chemical structures with biological and medicinal activity. Based on a documented library of the most common medicinal plants used by the indigenous people of North America, we have examined the anti-breast cancer properties of extracts from Juniperus communis (common juniper). Using methanolic extracts from juniper needles and branches, we conducted bioassay-guided fractionation to assess growth inhibition of the highly malignant MB231 breast cancer cell line. The isolation and identification of active juniper constituents were performed through high performance liquid chromatography (HPLC) and standard spectroscopic analysis (1D- and 2D-nuclear magnetic resonance [NMR] and low-resolution and high-resolution mass spectrometry). We characterized the diterpene isocupressic acid and the aryltetralin lignan deoxypodophyllotoxin as very potent inhibitors of cancer cell growth using dose-response and kinetic cell viability assays. Using a series of cellular and molecular tests, we also found that isocupressic acid and deoxypodophyllotoxin block MB231 cell cycling through the suppression of the ERK/MAPK and the NFκB signaling pathways. In addition to the blockade of the cell9s survival cascade, both compounds concomitantly induced CASPASE-3-dependant apoptosis of MB231 cells within hours of treatment. Our findings emphasize the potential and importance of natural products screening for new chemical entities with novel anticancer activities. Natural products research complemented with the wealth of information available through the ethnobotanical and ethnopharmacological knowledge of the indigenous natives will provide new candidate entities with desirable bioactivities to develop new cancer therapies. Citation Format: Gilles A. Robichaud, Nadia Picot, Stephanie Jean, Caitlyn Carpenter, Chris A. Gray. The characterization of anti-breast cancer compounds isolated from the Juniperus communis. [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 2266. doi:10.1158/1538-7445.AM2013-2266

Abstract 298: Breast cancer malignancy and drug sensitivity are regulated by mammaglobin 1.

Breast cancer metastasis, a complex process enabling tumour cells dissemination, accounts for more than 90% of breast cancer mortality. The identification of genes involved in breast cancer metastasis is thus essential mitigate disease progression One of these factors, mammaglobin 1 (MGB1), is specifically expressed in mammary epithelial tissues and overexpressed in mammary cancers. Normally, MGB1 plays an essential role in cellular homeostasis. More recently, studies show that MGB1 is a useful biomarker for prognostic application and the detection of metastastatic breast cancer. However, no studies reveal the cellular and molecular function of MGB1 in this disease. We therefore set out to elucidate the role of MGB1 in breast cancer processes. We developed a breast cancer model with conditioned MGB1 expression to assess the molecular and cellular processes regulated by that protein which lead to breast cancer cell malignancy. After investigation, we observed that loss of MGB1 expression led to the reduction of cancer cell growth which was supported by the suppression of p38, JNK, ERK and NFκB activities. We also found that MGB1 promotes cell migration which is supported through increased activities of FAK and matrix metalloproteinases. MGB1 also seems to foster epithelial to mesenchymal transitioning of cancer cells via the activation of Snail, Twist and Zeb1 pathways. Interestingly, we also found that MGB1 confers breast cancer cell sensitivity to apoptosis and to various anti-cancer drug treatments. Our study provides the first in dept molecular elucidation of MGB1 function in breast cancer processes. In summary, it extends our knowledge on the biology of breast cancer malignancy and gives us new tools to achieve new therapeutic and diagnostic strategies against this disease. Citation Format: Nadia Picot, Annie-Pier Beauregard, Roxann Guerette, Stephanie Jean, Gilles A. Robichaud. Breast cancer malignancy and drug sensitivity are regulated by mammaglobin 1. [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 298. doi:10.1158/1538-7445.AM2013-298