ammonium-trichloro(dioxoethylene-o-o--)tellurate and Multiple-Myeloma

The organotellurium compound, AS101, induces G(2)/M growth arrest and apoptosis in multiple myeloma (MM) cell lines. To characterize the mechanism by which AS101 promotes these effects, an antibody microarray analysis was performed, comparing levels of proteins and phosphoproteins in untreated versus AS101-treated mouse 5T33 MM cells. We found that AS101 down-regulated Ilk-1, Cdc25C and phosphorylation of Plk-1 on Thr210, all of which can affect the onset of mitosis or cell survival. In addition, AS101 inhibited the activity of a high molecular weight matrix metalloproteinase complex corresponding to the MMP-9/NGAL complex. Another signaling pathway that was affected by AS101 involves p53 and p65/RelA. Levels of both proteins were elevated upon treatment with AS101. Thus, multiple signaling pathways are involved in the G(2)/M growth arrest and apoptosis induced by AS101 in multiple myeloma, suggesting that if one pathway becomes unresponsive, the therapeutic effect of AS101 might persist through alternative pathways.

Topics: Animals; Apoptosis; Cell Line, Tumor; Ethylenes; G2 Phase Cell Cycle Checkpoints; Immunologic Factors; M Phase Cell Cycle Checkpoints; Matrix Metalloproteinases; Mice; Molecular Weight; Multiple Myeloma; Multiprotein Complexes; Proteomics; Signal Transduction; Transcription Factor RelA; Tumor Suppressor Protein p53

We previously showed that the organotellurium compound, ammonium trichloro (dioxyethylene-0-0') tellurate (AS101), has antitumoral activity in multiple myeloma (MM) cell lines. Here, we evaluated the antimyeloma activity of AS101 combined with low-dose melphalan, and also examined the activity of AS101 in the myeloma tumor microenvironment.. Isobologram analysis was performed to determine the interactions of AS101 and melphalan as a combination therapy. Growth arrest, apoptosis, and CD81 antigen were detected by flow cytometry. Using the 5T33MM mouse model, we evaluated mouse survival and serum levels of vascular endothelial growth factor (VEGF) and IgG(2b) paraprotein. We established cocultures of MS-5 bone marrow stromal cells and 5T33 MM cells in order to examine AS101 activity in a myeloma microenvironment model.. Combined treatment of AS101 with melphalan in vitro resulted in a synergistic inhibitory effect on growth, G(2)/M phase growth arrest, reduced IgG(2b) secretion, apoptotic cell death, and reduced fibronectin-mediated adhesion of MM cells. AS101 reduced VEGF secretion and protein expression in myeloma and cocultured cells, downregulated production of the matrix metalloproteinases (MMPs), MMP-9 and MMP-2, and also inhibited growth of the treated myeloma coculture. Combined treatment using AS101 and low dose of melphalan in vivo resulted in modest survival improvement of myeloma-bearing mice and in reduced IgG(2b) and VEGF serum levels.. AS101 in combination with a subtherapeutic dose of melphalan had increased beneficial effect relative to each agent alone in a mouse MM model. In addition, AS101 might be useful for targeting interactions between myeloma cells and the bone marrow microenvironment.

Topics: Animals; Antigens, CD; Antineoplastic Combined Chemotherapy Protocols; Apoptosis; Cell Adhesion; Cell Division; Down-Regulation; Drug Screening Assays, Antitumor; Drug Synergism; Ethylenes; Fibronectins; G2 Phase; Gene Expression Regulation, Neoplastic; Immunoglobulin G; Matrix Metalloproteinase 2; Matrix Metalloproteinase 9; Melphalan; Mice; Multiple Myeloma; Neoplasm Proteins; Neoplasms, Experimental; Paraproteins; Tetraspanin 28; Vascular Endothelial Growth Factor A

Multiple Myeloma (MM) is a clonal B-cell malignancy affecting both the immune and the skeletal systems, and accounts for 10% of all hematological cancers. The immunomodulator ammonium trichloro (dioxoethylene-O,O') tellurate (AS101) is a non-toxic compound which has direct anti-tumoral properties in several tumor models. The present study examined the anti-tumoral activity of AS101 in MM by targeting the Akt/Survivin signaling pathway, crucial for survival. We showed that AS101 inhibites cell proliferation and colonies formation of MM cell lines, in a dose-dependent manner. AS101 induced G(2)/M growth arrest and increased both cyclin-dependent kinase inhibitor p21(waf1) protein levels and Cdk1 (p34(cdc2))-inhibitory phosphorylation. Longer incubation of MM cells with AS101 resulted in accumulation of apoptotic cell population and in increased caspase 9, 3 and 7 activities. We also showed that AS101 down-regulated Akt phosphorylation and decreased expression of the inhibitor of apoptosis, survivin. Since Akt and survivin are potentials targets for MM therapy, we suggest that AS101, currently being used in clinical studies, may have therapeutic implications in myeloma and other hematopoietic malignancies.

Topics: Adjuvants, Immunologic; Animals; Antineoplastic Agents; Apoptosis; Cell Line, Tumor; Cell Proliferation; Cell Survival; Dose-Response Relationship, Drug; Drug Screening Assays, Antitumor; Ethylenes; Flow Cytometry; Inhibitor of Apoptosis Proteins; Mice; Microtubule-Associated Proteins; Multiple Myeloma; Proto-Oncogene Proteins c-akt; Repressor Proteins; Signal Transduction; Survivin