erucylphospho-n-n-n-trimethylpropylammonium and Multiple-Myeloma

Alkylphosphocholines are highly active against multiple myeloma (MM) cells in vitro and are devoid of myelotoxicity. Little is known about the determinants of MM cell responsiveness or resistance to these drugs. In this study we investigated the effects of disease-relevant cytokines, such as interleukin-6 (IL-6) and osteopontin (OPN), on the in vitro antimyeloma activity of erufosine and perifosine. The role of the Raf/MEK/ERK pathway was also studied. Exogenous IL-6 reduced the cytotoxicity of erufosine against OPM-2 cells and, to a smaller extent, against U-266 cells. This was accompanied by inhibition of apoptosis in OPM-2 cells. The efficacy of perifosine was similarly affected, but to a greater extent. IL-6 slightly enhanced the sensitivity of RPMI-8226 cells to erufosine, thus emphasizing the heterogeneity of MM. Induced overexpression of OPN isoforms made OPM-2 cells less sensitive to erufosine. In all cases of IL-6- or OPN-induced resistance, the effective concentrations of erufosine were still within the clinically achievable range. Like other alkylphosphocholines, erufosine enhanced Raf/MEK/ERK signaling in MM cells but in some cases this contributed to cytotoxicity.

Topics: Antineoplastic Agents; Cell Line, Tumor; Dose-Response Relationship, Drug; Drug Resistance, Neoplasm; Gene Expression Regulation, Neoplastic; Humans; Interleukin-6; MAP Kinase Signaling System; Multiple Myeloma; Organophosphates; Osteopontin; Phosphorylcholine; Proto-Oncogene Proteins c-raf; Quaternary Ammonium Compounds; Signal Transduction; Treatment Outcome

Erufosine is an i.v. injectable alkylphosphocholine which is active against various haematological malignancies in vitro. In the present study, its effects on multiple myeloma (MM) cell lines and on murine and human hematopoietic progenitor cells (HPCs) were investigated.. The following MM cell lines were used: RPMI-8226, U-266 and OPM-2. The cytotoxicity of erufosine against these cell lines was determined by the MTT-dye reduction assay. Bcl-2, Bcl-X(L) and pAkt expression levels, activation of caspases, as well as cleavage of PARP, were studied by Western blotting. Migration was evaluated by a modified Boyden-chamber assay. The haematologic toxicity of erufosine was assessed using clonogenicity assays with normal HPCs of murine or human origin.. Significant cytotoxic activity of erufosine against the MM cell lines was found. Comparison of the characteristics of erufosine-induced cell death in the three cell lines revealed a complex mode of action with apoptotic mechanisms prevailing in OPM-2 cells and non-apoptotic mechanisms prevailing in U-266 cells. The sensitivity of the MM cell lines to erufosine-induced apoptosis correlated inversely with the Bcl-X(L) expression level. Erufosine participated in synergistic interactions with various drugs. Furthermore, it showed potent migration-inhibiting activity in RPMI-8226 cells. Erufosine was not toxic to normal HPCs of murine or human origin and even stimulated progenitors from human umbilical cord blood to form granulocyte/macrophage colonies. Moreover, erufosine ameliorated the toxicity of bendamustine to murine HPCs.. Overall, the data presented reveal that erufosine could have potential as an antimyeloma drug and deserves further development.

Topics: Animals; Antineoplastic Agents; Apoptosis; bcl-X Protein; Blotting, Western; Cell Line, Tumor; Cell Movement; Drug Synergism; Female; Gene Expression Regulation, Neoplastic; Hematopoietic Stem Cells; Humans; Male; Mice; Mice, Inbred ICR; Multiple Myeloma; Organophosphates; Quaternary Ammonium Compounds

Multiple myeloma (MM) is a frequent hematological malignancy that is incurable despite recent developments, such as proteasome and angiogenic inhibitors. Erucylphospho-N,N,N-trimethylpropylammonium (erufosine) is an i.v. injectable alkylphosphocholine with antineoplastic activity based on an unusual mode of action and is currently undergoing clinical trials in leukemia patients. The aim of this investigation was to evaluate the efficacy of erufosine in MM cells and to study the modulation of cell-death pathways. The cytotoxicity of erufosine against three MM cell lines (RPMI-8226, U-266, and OPM-2) was determined by the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide-dye reduction assay. All MM cell lines responded to erufosine, RPMI-8226 cells being most and U-266 being least sensitive. The respective IC(50) values were 3.2 and 16.2 micromol/L. Various cell-death characteristics were studied in response to erufosine, such as morphological changes, oligonucleosomal DNA fragmentation, caspase activation, and poly (ADP)-ribose polymerase cleavage. Erufosine was found to cause cell shrinkage, chromatin condensation, and caspase-8 and -3 activation. Taken together, our data indicate that erufosine is a potential antimyeloma drug eliciting specific features of apoptotic cell death in vitro.

Topics: Apoptosis; Blotting, Western; Caspase 3; Caspase 8; Caspase 9; Cell Line, Tumor; Cell Proliferation; Cell Shape; Cell Survival; Chromatin; DNA Fragmentation; Dose-Response Relationship, Drug; Enzyme Activation; Humans; Indoles; Inhibitory Concentration 50; Microscopy, Fluorescence; Multiple Myeloma; Organophosphates; Poly(ADP-ribose) Polymerases; Quaternary Ammonium Compounds