Biomedical subjects

B Bonavida

Publications and source records attributed to B Bonavida.

261 records · Page 15Linked to original sources

PubMedDate not supplied

Natural killer cell anergy to cytokine stimulants in a subgroup of patients with heart failure: relationship to norepinephrine.

Heart failure is a disease characterized by chronically high levels of plasma norepinephrine and anergy in the cytotoxicity of circulating natural killer (NK) lymphocytes. This study shows that NK anergy extends to a significantly reduced cytotoxicity in response to the powerful NK stimulants, interleukin (IL)-2 and interferon (IFN)-alpha. Fifteen patients with heart failure, New York Heart Association stage III or IV, were studied for NK-cell-mediated cytotoxicity. The patients were divided into two groups based upon their NK cytotoxicity function: (1) those who had minimal baseline cytotoxicity and failed to respond following stimulation by IL-2 and IFN-alpha (n = 6), and (2) those who were about at the level of normal controls, and were responsive to IL-2 and IFN-alpha (n = 9). There was no relationship between the anergy and the etiology of the heart failure, laboratory indicators of heart failure, serum albumin or sodium, state anxiety, age or sex of the subjects. There was a statistically significant negative correlation between the response of NK cells to the stimulators IL-2 and IFN-alpha and the level of plasma norepinephrine in the heart failure patients. This was corroborated by in vitro testing of direct effects of norepinephrine on normal NK cells, which indicated that baseline cytotoxicity and the ability of these cells to respond to IL-2 were inhibited in a dose-dependent manner. The findings indicate that the NK cell anergy seen in heart failure patients extends to the response to the stimulators IL-2 and IFN-alpha in a subgroup of patients.

Adult↗

PubMedDate not supplied

Chemoimmunosensitization of the T24 human bladder cancer line to Fas-mediated cytotoxicity and apoptosis by cisplatin and 5-fluorouracil.

Previous studies have demonstrated that cisplatin (CDDP) sensitizes bladder cancer cells to Fas-mediated cytotoxicity and that CDDP also enhances the cytotoxic effect of 5-fluorouracil (5-FU). These agents mediate apoptosis and may share common intracellular pathways leading to cell killing. We reasoned that combination treatment with CDDP, 5-FU and anti-Fas monoclonal antibody (mAb) might overcome the drug-resistance. We investigated whether CDDP, 5-FU and anti-Fas mAb synergize in cytotoxicity and apoptosis against the T24 bladder cancer line. Cytotoxicity was monitored by a one day microculture tetrazolium dye assay. Treatment of T24 cells with anti-Fas mAb in combination with CDDP or 5-FU resulted in a synergistic cytotoxic effect. In addition, combination treatment of T24 cells with CDDP, 5-FU and anti-Fas mAb further enhanced the synergistic cytotoxicity achieved by two agents. The synergy achieved in cytotoxicity with CDDP, 5-FU and anti-Fas mAb was also achieved in apoptosis. The current study demonstrates that combination treatment of bladder cancer cells with CDDP, 5-FU and anti-Fas mAb overcomes their resistance. In addition, the sensitization required low concentrations of CDDP and 5-FU, and thus supporting the potential in vivo application of combination of CDDP, 5-FU and immunotherapy in the treatment of drug-resistant bladder cancer.

Antibodies, Monoclonal↗

PubMedDate not supplied

Oncostatin M (OM) promotes the growth of DU 145 human prostate cancer cells, but not PC-3 or LNCaP, through the signaling of the OM specific receptor.

BACKGROUND: Oncostain M (OM) is a member of the interleukin-6 (IL-6) cytokine family and all members utilize gp130 as a common signal transducing receptor. Tyrosine phosphorylation of the transcription factor STAT3 plays an important role in IL-6 cytokine family-mediated reactions. OM signals are transduced through two different OM receptor complexes: a leukemia inhibitory factor (LIF)/OM receptor (a heterodimer of LIFR beta and gp130) and an OM specific receptor (a heterodimer of OMR beta and gp130). This study examined the expression of these two OM receptors as well as the effect of OM on the growth of prostate carcinoma cell lines. MATERIALS AND METHODS: PC-3, DU 145 and LNCaP cells were used. The expression of OMR beta and LIFR beta was determined by RT-PCR. Tyrosine phosphorylation of STAT3 was analyzed by Western blotting. RESULTS: OM promoted the growth of DU 145 but not that of PC-3 and LNCaP. LIF had no effect on the growth of any of these cell lines. DU 145 and PC-3 expressed much higher levels of OMR beta mRNA than those of LIFR beta mRNA. Neither OMR beta nor LIFR beta mRNA was detected in LNCaP. OM, but not LIF, induced rapid tyrosine phosphorylation of STAT3 in DU 145. PC-3 lacked STAT3 expression. CONCLUSIONS: OM has been known to be a cytostatic cytokine for tumor cells. Conversely, we show that OM promotes the growth of DU 145. Further, our findings suggest that the growth-promoting signals of OM is mediated through the OM specific receptor with subsequent activation of STAT3.

Cell Division↗

PubMedDate not supplied

Potentiation of fludarabine cytotoxicity on non-Hodgkin's lymphoma by pentoxifylline and rituximab.

BACKGROUND: Fludarabine has become a drug of prominent use in hematopoietic malignancies exhibiting indolent growth profiles. Some studies show, however, that nearly 50% of patients are fludarabine-resistant from the very onset of therapy. Others relapse after an initial response rarely lasting more than 2 years. For this reason, modulating agents have been considered for use with fludarabine to potentiate fludarabine cytotoxicity and circumvent drug resistance. The chimeric anti-CD20 monoclonal antibody, Rituximab (IDEC-C2B8), is used to treat patients with low grade and follicular B-cell non-Hodgkin's lymphoma. Rituximab is known to inhibit the cell progression of tumor B cells and to sensitize them to chemotherapeutic drugs. A slower cell progression may enhance the efficacy of fludarabine incorporation, thus increasing its cytotoxicity. Therefore, the use of fludarabine and Rituximab in combination could potentiate fludarabine cytotoxicity. The methylxanthine, pentoxifylline, disrupts DNA repair mechanisms within a cell by not allowing a cell to arrest at the G2/M checkpoint. By not allowing cells to repair fludarabine DNA incorporation, pentoxifylline was thought to increase fludarabine-induced cytotoxicity in tumor cells. We tested these hypotheses in vitro. MATERIALS AND METHODS: Analysis of cytotoxicity was performed using the XTT assay on tumor cell lines and patient samples. RESULTS: Tumor cell models, including two B-cell non-Hodgkin's lymphoma cell lines and a T-cell leukemia cell line, were shown to respond more effectively to fludarabine therapy in the presence of Rituximab or pentoxifylline. Two freshly derived B-cell chronic lymphocytic leukemia patient samples were also seen to exhibit a better response with a combination of fludarabine and pentoxifylline than with either alone. CONCLUSION: This study proves the hypothesis that Rituximab and pentoxifylline may provide a clinical approach to hinder the outgrowth of drug refractory tumor cells and achieve a longer period of remission.

Antibodies, Monoclonal↗

PubMedDate not supplied

Activation of human peripheral-blood-derived monocytes by cis-diamminedichloroplatinum: enhanced tumoricidal activity and secretion of tumor necrosis factor-alpha.

The anticancer agent cis-diamminedichloroplatinum (CDDP) has been shown to have immunopotentiating and immuno-suppressive properties depending on the CDDP concentration used. Treatment of human peripheral-blood-derived monocytes (PBM) in vitro with low concentrations of CDDP resulted in a significant potentiation of antitumor cytotoxicity as assessed in an 18-hour 51Cr release assay. The potentiation of cytotoxicity by CDDP was also observed with PBM treated with recombinant interferon-gamma (rIFN-gamma). The monocyte-mediated cytotoxicity was significantly inhibited when antitumor necrosis factor (TNF) antibody was added to the assay culture. The role of TNF in the cytotoxic mechanism was further corroborated by demonstrating that significant levels of immunoreactive TNF-alpha in the supernatants were detected by ELISA. Further, supernatants derived from CDDP-treated monocytes were cytotoxic to the TNF-sensitive tumor cells and the cytotoxicity was neutralized by the addition of anti-TNF antibody. The secretion of TNF-alpha by CDDP-treated monocytes was readily detected as early as 4 h after culture and was dependent on de novo protein synthesis as inhibitors of RNA and protein synthesis abolished TNF-alpha secretion. Altogether, these results demonstrate that CDDP can potentiate monocyte-mediated antitumor cytotoxicity and stimulates TNF-alpha synthesis and secretion.

Cisplatin↗

PubMedDate not supplied

Cytotoxic activity of synthetic aza alkyl lysophospholipids against drug sensitive and drug resistant human tumor cell lines.

The anti-tumor cytotoxic activity of four newly synthesized aza alkyl lysophospholipids (AALP), namely BN 52205, BN 52207, BN 52208 and BN 52211, was investigated. Using the 51Cr release assay, the four compounds were endowed with cytotoxic activity, in a concentration-dependent fashion, against various human tumor cell lines of different histological origin. Two different mechanisms appear to be involved in the AALP-mediated cytotoxicity. A rapid membrane damaging effect was observed in less than one hour's incubation of tumor cells with AALP and cytotoxicity was temperature-independent when AALP were used at greater than or equal to 200 micrograms/ml. A slower cytotoxic mechanism was observed after 18 hours incubation at 37 degrees C when AALP were used at concentrations of 30-100 micrograms/ml. The pattern and magnitube of the cytotoxic activity achieved with all the 4 AALP compounds tested were similar and the cytotoxicity mediated by combination of two compounds was additive. In addition to the cytotoxic effect, the AALP compounds also exerted a cytostatic anti-tumor effect, as assessed by inhibition of 3H TdR incorporation. Using a variety of human tumor cell lines as targets, the cytotoxic effect observed with the AALP was noted with tumor cells that were either sensitive or resistant to TNF-alpha and/or chemotherapeutic drugs such as mitomycin C, adriamycin and cis-platinum. The LD50 toxicity in mice was 100-125 mg/kg. The present findings demonstrate that AALP are cytotoxic to a variety of human tumor cell lines and do not appear to discriminate between drug/cytokine sensitive or resistant cells. Thus the present study suggests that some aza alkyl lysophospholipids may be considered as potential anticancer agents.

Drug Screening Assays, Antitumor↗

PubMedDate not supplied

Augmentation of cytotoxicity of lymphokine activated killer cells on ovarian tumor cells by various biological response modifiers.

The effect of combining lymphokine activated killer (LAK) cells with either recombinant interleukin-2 (rlL-2), recombinant interferon-alpha (rIFN-alpha), recombinant tumor necrosis factor (rTNF) or streptococcal preparation OK-432 were assessed, using Raji, 2 kinds of cultured ovarian lines (PA-1 and SKOV-3), and 7 fresh ovarian tumor lines. LAK cells were generated by culturing peripheral blood lymphocytes (PBL) with rIL-2 for 3-5 days. The simultaneous combination of LAK cells with rIFN alpha or OK-432 augmented the cytotoxicity of LAK cells. The susceptibility of tumor cells to LAK cells also increased after the pretreatment of tumor cells with OK-432. These results suggest that the simultaneous injection of LAK cells with rIFN-alpha or OK-432 and the intralesional injection of OK-432 prior to the adoptive transfer of LAK cells may be a beneficial combination treatment for LAK treatment.

Biological Products↗

PubMedDate not supplied

Natural killer cell subsets: maturation, differentiation and regulation.

Studies of the maturation and differentiation of human peripheral blood-derived natural killer (NK) cells were examined on isolated three subsets of NK cells. These subsets were separated based on their ability to bind and/or kill the target cells. Flow cytometry and cell-sorting analyses enabled the separation of free, binder and killer cells. These three subsets were subjected to various phenotypic and functional analyses. The findings suggest that the three subsets belong to the same lineage of maturation and differentiation, e.g. free and binders can mature into killer cells. The killer cells are not terminally differentiated as they respond to IL-2 and targets and proliferate. The response of free cells to IL-2 and IFN-alpha proceeds by distinct pathways, namely IL-2-mediated activation and proliferation is under the control of endogenous TNF-alpha production but not IFN-alpha-mediated activation. Regulation of several surface markers' expression is associated with functional maturation. In addition to activation, the cells can also undergo inactivation or anergy following interaction with targets. The binder and killer cells are the predominant subsets that become inactivated for cytotoxicity and their response to IL-2 is inhibited. The studies also show that various events associated with activation of cytotoxicity are under different regulatory controls than those for proliferation and secretion. These studies suggest that biochemical and molecular events associated with signalling and differentiation are now possible to unravel using the NK subsets.

Cell Differentiation↗

PubMedDate not supplied

Dexamethasone enhances expression of membrane and soluble interleukin-6 receptors by prostate carcinoma cell lines.

BACKGROUND: Primary prostate carcinoma cells constitutively secrete interleukin-6 (IL-6), and high levels of IL-6 receptor are detected in prostate carcinoma tissues. These findings have implicated IL-6 in the growth and differentiation of prostate carcinomas. Herein, we examined the regulation of IL-6 receptor complex (IL-6R alpha/gpl30) in prostate carcinoma cell lines. We also analyzed the production of soluble IL-6R alpha (IL-6sR) because IL-6sR can confer the IL-6 responsiveness on IL-6R alpha-lacking cells. MATERIAL AND METHODS: Three established prostate carcinoma cell lines, PC-3, DU 145 and LNCaP, were analyzed. Protein tyrosine-phosphorylation was detected by immunoblotting. The expression of IL-6R alpha, gpl30 and IL-6sR was determined by RT-PCR, flow cytometry and ELISA. RESULTS: IL-6 induced tyrosine-phosphorylated proteins in LNCaP but not in PC-3 or DU 145, indicating that LNCaP cells express the functional IL-6 receptor. Dexamethasone (Dex)-treatment induced functional IL-6 receptors on DU 145 and PC-3 through upregulation of IL-6R alpha and gpl30. In addition, LNCaP, Dex-treated PC-3 and Dex-treated DU 145 secreted large amounts of IL-6sR. CONCLUSIONS: The expression of IL-6 receptor by prostate carcinoma cell lines was augmented by glucocorticoid. We propose prostate carcinomas as IL-6sR producing tumors, and IL-6sR may modulate the behavior of not only the tumor cells but also the surrounding cells.

Animals↗