Effect of antineoplastic drugs on human leukocyte-mediated cytotoxicity against herpes simplex virus infected cells

Chemotherapy-induced Apoptosis of S-type Neuroblastoma Cells Requires Caspase-9 and Is Augmented by CD95/Fas Stimulation

Stromal or S-type tumor cells are a distinct lineage found in neuroblastoma tumors and have an important role in the biology of this disease. Anticancer agents induce apoptosis through death receptor- and mitochondria-initiated pathways. The object of this work was to determine the involvement of these pathways in the response to doxorubicin (Dox) and cisplatin (CDDP) in S-type neuroblastoma cells. Both drugs activated caspase-9 and caspase-3 but not caspase-8. Caspase-9-specific inhibition blocked S-type cell death induced by Dox. SH-EP1 cells transfected to express dominant negative mutant caspase-9, but not those expressing DN caspase-8, were resistant to Dox- and CDDP-induced apoptosis. The lack of caspase-8 involvement in chemotherapy-induced death was not the result of an intrinsic inability of these cells to activate this enzyme because when they were treated with tumor necrosis factor-related apoptosis-inducing ligand, caspase-8 was activated. We also found that both drugs up-regulated CD95/Fas expression but that CD95/Fas signaling was not necessary for cell killing. Experiments testing the response of chemotherapy-treated cells to agonists of the CD95/Fas receptor established that Dox and CDDP treatment sensitizes cells to CD95/Fas killing. Together, these results are consistent with a model in which caspase-9 is of central importance in the death mechanism utilized by these drugs in S-type cells. Although the death response is not dependent on CD95/Fas, concomitant stimulation of this receptor amplifies the death response in drug-treated cells.

Constitutively active NFkappa B is required for the survival of S-type neuroblastoma

The NFkappaB transcription factors can both promote cell survival and induce apoptosis depending on cell type and context. Neuroblastoma (NB) cells display two predominant culture phenotypes identified as N- and S-types. Malignant S-type cells express neither high levels of MYCN nor Bcl-2, suggesting that other survival mechanisms are important. We characterized NFkappaB activity in S-type cells and determined its role in their survival. S-type lines (SH-EP1 and SK-N-AS) were treated with pyrrolidine dithiocarbamate (PDTC), a NFkappaB inhibitor, or l-1-tosylamido-2-phenylethyl chloromethyl ketone (TPCK), a serine protease inhibitor that blocks IkappaBalpha degradation. Both agents induced cell death, suggesting that constitutive NFkappaB activity is required for survival. The transient expression of a super-repressor IkappaBalpha mutant killed S-type cells. The inhibition of NFkappaB produced an apoptotic response characterized by the collapse of the mitochondrial transmembrane electrochemical gradient, caspase-9 activation, and apoptotic DNA changes. Constitutive NFkappaB DNA binding activity specifically involving p65 and p50 was demonstrated in S- but not N-type cells by electromobility supershift and gene reporter assays. This study demonstrates a role for NFkappaB in the survival of S-type NB tumor cells and suggests that NFkappaB activity and function differ according to NB tumor cell phenotype.

Effect of anticancer drugs on the release of interleukin-6 in vitro

This study investigates the effects of anticancer drugs and immunomodulating agents on the release of interleukin-6 (IL-6) from lipopolysaccharide-stimulated human peripheral blood mononuclear leucocytes in vitro. The addition of non-cytotoxic concentrations of Adriamycin (doxorubicin), vincristine and 4-OOH-cyclophosphamide (the in vitro active analogue of cyclophosphamide) resulted in suppression of IL-6 release. The drugs bleomycin, FK156 [D-lactoyl-L-alanyl-gamma-D-glutamyl-(L)-meso-diaminopimelyl-(L)-g lycine], FK565 [heptanoyl-gamma-D-glutamyl-(L)-meso-diaminopimelyl-(D)-alan ine] and the immunosuppressive agent cyclosporin A did not alter the release of IL-6 in the same experimental system.

Inhibition of release of interleukin-2 by vincristine and vinblastine

The antineoplastic drugs Vincristine (VCR) and Vinblastine (VBL) were tested for their effects on Concanavalin A induced Interleukin-2 (IL-2) release by rat splenocytes. Both drugs were found to inhibit IL-2 release in vitro. This effect was noted at doses of 10 ng/ml and 100 ng/ml in case of VBL and at doses of 1 ng/ml, 10 ng/ml and 100 ng/ml with VCR. The in vivo effect of these drugs was studied by injection into rats three days before culture of splenocytes. This also resulted in inhibition of IL-2 release. The effect was manifested with VCR at doses of 0.1 mg/kg bw and 0.5 mg/kg bw and with VBL at 2 mg/kg bw. These drugs were also tested for their effect on Interleukin-1 (IL-1) release by lipopolysaccharide (LPS) stimulated rat peritoneal exudate cells (PEC's) in vitro. No modulation of the production of IL-1 was seen.

Activity of rabbit monocytes, macrophages, and neutrophils in antibody-dependent cellular cytotoxicity of herpes simplex virus-infected corneal cells

Rabbit phagocytes were examined for their ability to kill target cells infected with herpes simplex virus by antibody-dependent cellular cytotoxicity. Two sources of rabbit corneal cells were used as targets: Staaten Seruminstitut Rabbit Cornea (a continuous cell line) and stromal keratocytes from the middle layer of corneas excised from New Zealand white rabbits. Peritoneal exudate and alveolar macrophages were found to be the most active effector cells, followed by blood neutrophils and monocytes. Peritoneal exudate and alveolar macrophages killed target cells with dilutions of antibody as high as 1:10,000. Monocyte antibody-dependent cellular cytotoxicity activity was absent in over one-third of the rabbits tested and was only weakly active in positive rabbits. In vitro aging of monocytes did not enhance activity. Antibody reactive with peritoneal exudate macrophages, alveolar macrophages, and blood neutrophil effector cells appeared 7 days after intracorneal injection of infectious herpes simplex virus. Results of these studies show that in vitro assays with a complete rabbit system (effectors cells, antibody, and target cells) can be developed to monitor herpetic disease and suggest an active role for rabbit phagocytes in cytotoxicity of herpes simplex virus-infected cells.