frondoside-a and Breast-Neoplasms

In the present study, we investigated the effect of Salinomycin on the survival of three human breast cancer cell lines MCF-7, T47D and MDA-MB-231 grown in adherent culture conditions.. Cell viability was measured by Cell Titer-Glo and Trypan blue exclusion assay. Apoptosis was determined by caspase 3/7 activation, PARP cleavage and Annexin V staining. Cell cycle distribution was assessed by propidium iodide flow cytometry. Senescence was confirmed by measuring the senescence-associated β-galactosidase activity. Changes in protein expression and histone hyperacetylation was determined by western blot and confirmed by immunofluorescence assay.. Salinomycin was able to inhibit the growth of the three cell lines in time- and concentration-dependent manners. We showed that depending on the concentrations used, Salinomycin elicits different effects on the MDA-MB-231 cells. High concentrations of Salinomycin induced a G2 arrest, downregulation of survivin and triggered apoptosis. Interestingly, treatment with low concentrations of Salinomycin induced a transient G1 arrest at earlier time point and G2 arrest at later point and senescence associated with enlarged cellmorphology, upregulation of p21 protein, increase in histone H3 and H4 hyperacetylation and expression of SA-β-Gal activity. Furthermore, we found that Salinomycin was able to potentiate the killing of the MCF-7 and MDA-MB-231 cells, by the chemotherapeutic agents, 4-Hydroxytamoxifen and frondo side A, respectively.. Our data are the first to link senescence and histone modifications to Salinomycin.. This study provides a new insight to better understand the mechanism of action of Salinomycin, at least in breast cancer cells.

Topics: Acetylation; Anti-Bacterial Agents; Apoptosis; Breast Neoplasms; Cell Line, Tumor; Cell Proliferation; Cellular Senescence; Cyclin-Dependent Kinase Inhibitor p21; Cytoskeletal Proteins; Female; G2 Phase; Glycosides; Histones; Humans; Inhibitor of Apoptosis Proteins; Pyrans; Survivin; Triterpenes

Frondoside A, derived from the sea cucumber Cucumaria frondosa has demonstrable anticancer activity in several models, however, the ability of Frondoside A to affect tumor metastasis has not been reported. Using a syngeneic murine model of metastatic breast cancer, we now show that Frondoside A has potent antimetastatic activity. Frondoside A given i.p. to mice bearing mammary gland-implanted mammary tumors, inhibits spontaneous tumor metastasis to the lungs. The elevated Cyclooxygenase-2 activity in many malignancies promotes tumor growth and metastasis by producing high levels of PGE(2) which acts on the prostaglandin E receptors, chiefly EP4 and EP2. We examined the ability of Frondoside A to modulate the functions of these EP receptors. We now show that Frondoside A antagonizes the prostaglandin E receptors EP2 and EP4. (3)H-PGE(2) binding to recombinant EP2 or EP4-expressing cells was inhibited by Frondoside A at low μM concentrations. Likewise, EP4 or EP2-linked activation of intracellular cAMP as well as EP4-mediated ERK1/2 activation were also inhibited by Frondoside A. Consistent with the antimetastatic activity observed in vivo, migration of tumor cells in vitro in response to EP4 or EP2 agonists was also inhibited by Frondoside A. These studies identify a new function for an agent with known antitumor activity, and show that the antimetastatic activity may be due in part to a novel mechanism of action. These studies add to the growing body of evidence that Frondoside A may be a promising new agent with potential to treat cancer and may also represent a potential new modality to antagonize EP4.

Topics: Animals; Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cyclic AMP; Female; Glycosides; Humans; Inhibitory Concentration 50; Lung Neoplasms; MAP Kinase Signaling System; Mice; Mice, Inbred BALB C; Receptors, Prostaglandin E, EP2 Subtype; Receptors, Prostaglandin E, EP4 Subtype; Second Messenger Systems; Triterpenes; Tumor Burden; Xenograft Model Antitumor Assays

Metastasis and invasion are among the main causes of death in patients with malignant tumors. The aim of this study was to determine the anti-invasive activity of frondoside A against human breast cancer cells. We investigated the inhibitory effect of frondoside A on cell clonogenicity, invasion and migration in TPA-stimulated human breast cancer cells at non-cytotoxic concentrations. Frondoside A significantly attenuated TPA-induced colony formation, invasion and migration in MBA-MB-231 human breast cancer cells. Induction of MMP-9 is especially important for the metastasis of many cancer tumor cell types. Additionally, we found that frondoside A suppresses TPA-induced MMP-9 enzymatic activity, secretion and expression. This effect was associated with reduced activation of AP-1 and NF-κB, and correlated with enhanced expression of TIMP-1 and TIMP-2. Frondoside A significantly inhibited the TPA-induced MMP-9 expression possibly via the suppression of AP-1 and NF-κB signaling pathways. Frondoside A reduces the activation of the PI3K/Akt, ERK1/2 and p38 MAPK signals. These results suggest that the anti-metastatic effects of frondoside A on human breast cancer cells might result from inhibited TPA activation of AP-1 and NF-κB and reduced TPA activation of PI3K/Akt, ERK1/2 and p38 MAPK signals, ultimately leading to downregulation of MMP-9 expression. These results indicate the role of frondoside A in metastasis and its underlying molecular mechanisms, thus, suggesting frondoside A as a chemopreventive agent for metastatic breast cancer.

Topics: Antineoplastic Agents; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Extracellular Signal-Regulated MAP Kinases; Female; Glycosides; Humans; MAP Kinase Signaling System; Matrix Metalloproteinase 9; Neoplasm Invasiveness; Neoplasm Metastasis; NF-kappa B; p38 Mitogen-Activated Protein Kinases; Phosphatidylinositol 3-Kinases; Proto-Oncogene Proteins c-akt; RNA Interference; RNA, Small Interfering; Tetradecanoylphorbol Acetate; Transcription Factor AP-1; Triterpenes

Breast cancer is a major challenge for pharmacologists to develop new drugs to improve the survival of cancer patients. Frondoside A is a triterpenoid glycoside isolated from the sea cucumber, Cucumaria frondosa. It has been demonstrated that Frondoside A inhibited the growth of pancreatic cancer cells in vitro and in vivo. We investigated the impact of Frondoside A on human breast cancer cell survival, migration and invasion in vitro, and on tumor growth in nude mice, using the human estrogen receptor-negative breast cancer cell line MDA-MB-231. The non-tumorigenic MCF10-A cell line derived from normal human mammary epithelium was used as control. Frondoside A (0.01-5 μM) decreased the viability of breast cancer cells in a concentration- and time-dependent manner, with 50%-effective concentration (EC50) of 2.5 μM at 24h. MCF10-A cells were more resistant to the cytotoxic effect of Frondoside A (EC50 superior to 5 μM at 24 h). In the MDA-MB-231 cells, Frondoside A effectively increased the sub-G1 (apoptotic) cell fraction through the activation of p53, and subsequently the caspases 9 and 3/7 cell death pathways. In addition, Frondoside A induced a concentration-dependent inhibition of MDA-MB-231 cell migration and invasion. In vivo, Frondoside A (100 μg/kg/dayi.p. for 24 days) strongly decreased the growth of MDA-MB-231 tumor xenografts in athymic mice, without manifest toxic side-effects. Moreover, we found that Frondoside A could enhance the killing of breast cancer cells induced by the chemotherapeutic agent paclitaxel. These findings identify Frondoside A as a promising novel therapeutic agent for breast cancer.

Topics: Animals; Breast Neoplasms; Cell Line, Tumor; Cell Movement; Cell Proliferation; Cell Survival; Female; Glycosides; Humans; Mice; Neoplasm Invasiveness; Signal Transduction; Triterpenes; Xenograft Model Antitumor Assays