pregna-4-17-diene-3-16-dione and Breast-Neoplasms

Many breast cancer cells acquire multidrug resistance (MDR) mediated by ABC transporters such as breast cancer resistance protein (BCRP/ABCG2). Here we show that incubation of human breast cancer MDA-MB-231 cells with farnesoid X receptor antagonist guggulsterone (gug) and retinoid X receptor agonist bexarotene (bex) elevated ceramide, a sphingolipid known to induce exosome secretion. The gug+bex combination reduced cellular levels of BCRP to 20% of control cells by inducing its association and secretion with exosomes. Exogenous C6 ceramide also induced secretion of BCRP-associated exosomes, while siRNA-mediated knockdown or GW4869-mediated inhibition of neutral sphingomyelinase 2 (nSMase2), an enzyme generating ceramide, restored cellular BCRP. Immunocytochemistry showed that ceramide elevation and concurrent loss of cellular BCRP was prominent in Aldefluor-labeled breast cancer stem-like cells. These cells no longer excluded the BCRP substrate Hoechst 33342 and showed caspase activation and apoptosis induction. Consistent with reduced BCRP, ABC transporter assays showed that gug+bex increased doxorubicin retention and that the combination of gug+bex with doxorubicin enhanced cell death by more than fivefold. Taken together, our results suggest a novel mechanism by which ceramide induces BCRP secretion and reduces MDR, which may be useful as adjuvant drug treatment for sensitizing breast cancer cells and cancer stem cells to chemotherapy.

Topics: ATP Binding Cassette Transporter, Subfamily G, Member 2; ATP-Binding Cassette Transporters; Bexarotene; Breast Neoplasms; Cell Death; Cell Line, Tumor; Ceramides; Down-Regulation; Doxorubicin; Drug Resistance, Neoplasm; Drug Synergism; Exosomes; Humans; Neoplasm Proteins; Pregnenediones; Tetrahydronaphthalenes

z-Guggulsterone (z-Gug) and Gugulipid (GL) have been used to treat a variety of ailments. We now report their anti-cancer effect and mechanism against human breast cancer.. Using the human estrogen receptor-positive (MCF-7) and triple-negative (MDA-MB-231) breast cancer cells as well as the normal human mammary epithelial cell line (HMEC), we evaluated the anti-breast-cancer efficacy and apoptosis inducing activity of GL. We determined the cellular and molecular mechanism of GL-inhibited breast cancer cell growth.. GL significantly inhibited growth of MCF-7 and MDA-MB-231 cells with an IC50~2 μM at pharmacologically relevant concentrations standardized to its major active constituent z-Gug. The GL-induced growth inhibition correlated with apoptosis induction as evidenced by an increase in cytoplasmic histone-associated DNA fragmentation and caspase 3 activity. The GL-induced apoptosis was associated with down-regulation of the β-Catenin signaling pathway. The decreased expression of Wnt/β-Catenin targeting genes, such as cyclin D1, C-myc and survivin, and the inhibition of the activity of the transcription factor (T-cell factor 4, TCF-4) were observed in GL-treated breast cancer cells. The GL treatment resulted in a significant reduction of β-Catenin /TCF-4 complex in both of the cancer cells. The GL-induced apoptotic cell death was significantly enhanced by RNA Interference of β-Catenin and TCF-4. On the other hand, the normal human mammary epithelial cell HMEC, compared with the human breast cancer cells, is significantly more resistant to growth inhibition and apoptosis induction by GL.. The present study indicates that the β-Catenin signaling pathway is the target for GL-induced growth inhibition and apoptosis in human breast cancer.

Topics: Apoptosis; Basic Helix-Loop-Helix Leucine Zipper Transcription Factors; beta Catenin; Breast Neoplasms; Cell Cycle; Cell Line, Tumor; Commiphora; Humans; Medicine, Ayurvedic; Plant Extracts; Plant Gums; Pregnenediones; Protein Binding; Signal Transduction; Transcription Factor 4; Transcription Factors

Νuclear factor-κB (NF-κB) and activator protein-1 (AP-1) are major transcription factors that have been associated with breast cancer metastasis by inducing matrix metalloproteinase-9 (MMP-9) expression. In this study, we investigated the inhibitory effects of guggulsterone isomers (cis or trans) on 12-O-tetradecanoylpho-bol-13-acetate (TPA)-induced MMP-9 expression. Cis-guggulsterone inhibited TPA-induced MMP expression by blocking IκB kinase (IKK)/NF-κB signaling, whereas trans-guggulsterone blocked mitogen-activated protein kinase (MAPK)/AP-1 signaling. Cis-guggulsterone was more potent than trans-guggulsterone in the inhibition of TPA-induced MMP-9 expression and invasion of MCF-7 cells. Furthermore, we found that the combination of these isomers exerted an additive effect on the inhibition of MCF-7 cell invasion. These results suggest that guggulsterone isomers downregulate MMP-9 expression and tumor cell invasion through the isomer-specific suppression of IKK/NF-κB and MAPK/AP-1 activation. In addition, the suppression of MMP-9 expression correlated well with the inhibition of cell invasion.

Topics: Antineoplastic Agents, Phytogenic; Breast; Breast Neoplasms; Cell Survival; Commiphora; Female; Humans; I-kappa B Kinase; Isomerism; Matrix Metalloproteinase 9; MCF-7 Cells; Mitogen-Activated Protein Kinases; Neoplasm Invasiveness; NF-kappa B; Pregnenediones; Signal Transduction; Tetradecanoylphorbol Acetate; Transcription Factor AP-1

Topics: Anticarcinogenic Agents; Apoptosis; Barrett Esophagus; Breast Neoplasms; Cell Proliferation; DNA-Binding Proteins; Humans; Melanoma; Pregnenediones; Receptors, Cytoplasmic and Nuclear; STAT3 Transcription Factor; Transcription Factors

Bone resorption is commonly associated with aging and with certain types of cancer, including multiple myeloma and breast cancer. What induces bone resorption is not fully understood, but the role of osteoclasts is well established. Recently, receptor activator of nuclear factor-kappaB (NF-kappaB) ligand (RANKL), a member of the tumor necrosis factor superfamily, was implicated as a major mediator of bone resorption, suggesting that agents that can suppress RANKL signaling have the potential to inhibit bone resorption or osteoclastogenesis. Guggulsterone [4,17(20)-pregnadiene-3,16-dione], isolated from the guggul tree Commiphora mukul and used to treat osteoarthritis and bone fractures, was recently shown to antagonize the farnesoid X receptor, decrease the expression of bile acid-activated genes, and suppress the NF-kappaB activation induced by various carcinogens. We investigated whether guggulsterone could modulate RANKL signaling and osteoclastogenesis induced by RANKL or tumor cells. We found that treatment of monocytes with guggulsterone suppressed RANKL-activated NF-kappaB activation (as indicated by gel-shift assay) and that this suppression correlated with inhibition of IkappaBalpha kinase and phosphorylation and degradation of IkappaBalpha, an inhibitor of NF-kappaB. Guggulsterone also suppressed the differentiation of monocytes to osteoclasts in a dose-dependent and time-dependent manner. Suppression of osteoclastogenesis by the NF-kappaB-specific inhibitory peptide implies a link between NF-kappaB and osteoclastogenesis. Finally, differentiation to osteoclasts induced by coincubating human breast tumor cells (MDA-MB-468) or human multiple myeloma (U266) cells with monocytes was also completely suppressed by guggulsterone. Collectively, our results indicate that guggulsterone suppresses RANKL and tumor cell-induced osteoclastogenesis by suppressing the activation of NF-kappaB.

Topics: Bone Resorption; Breast Neoplasms; Carrier Proteins; Cell Differentiation; Commiphora; Female; Humans; I-kappa B Kinase; Membrane Glycoproteins; Monocytes; Multiple Myeloma; NF-kappa B; Osteoclasts; Peptide Fragments; Phosphorylation; Pregnenediones; RANK Ligand; Receptor Activator of Nuclear Factor-kappa B; Tumor Cells, Cultured