Biomedical subjects

E Bonmassar

Publications and source records attributed to E Bonmassar.

At least 37 records · Page 2Linked to original sources

PubMed1999

In vitro infection of CD4+ T lymphocytes with HTLV-I generates immortalized cell lines coexpressing lymphoid and myeloid cell markers.

The human T cell leukemia/lymphoma virus (HTLV-I) is the etiologic agent of adult T cell leukemia (ATL). CD4+ lymphocytes are the preferential targets of infection, even though other cell types can be infected in vitro by the virus. Although ATL cells show CD3 and CD4 surface markers, some ATL-derived cell lines were reported to express also myeloid antigens. In order to analyze possible phenotypic changes induced by HTLV-I after infection of human lymphocytes, CD4+ cells were isolated from peripheral blood of three healthy donors, by separation through immunomagnetic beads. CD4+ lymphocytes were then infected by coculture with irradiated HTLV-I producing MT-2 cells. The phenotypic profile of infected cells was studied by flow cytometric analysis using monoclonal antibodies against lymphoid (CD3, CD4, TCR alpha/beta) and myelomonocitic markers (CD13, CD14, CD15, CD33, CD34). The results show that HTLV-I immortalized cell lines coexpressed CD13, CD33 and lymphoid markers. No expression of CD14, CD15 and CD34 was observed. These data suggest that the presence of both myeloid and lymphoid phenotype in HTLV-I infected T cells is the results of an induction rather than a selection mechanism.

Biomarkers, Tumor↗

PubMed1999

Treatment with temozolomide and poly(ADP-ribose) polymerase inhibitors induces early apoptosis and increases base excision repair gene transcripts in leukemic cells resistant to triazene compounds.

Methylating triazenes have shown marked antileukemic effects, possibly through generation of a variety of DNA adducts. Cells tolerant to O6-methylguanine due to a defect in the mismatch repair system (MRS), might become sensitive to other methyl adducts, by inhibiting the N-methylpurine repair, which requires base excision repair (BER) and poly(ADP-ribose) polymerase (PADPRP). Therefore, MRS-deficient Jurkat leukemic cells resistant to methylating triazenes, have been treated with temozolomide (TZM) and PADPRP inhibitors. Expression of PADPRP or molecules involved in the BER system [3-methylpurine-DNA glycosylase (MPG) and X-ray repair cross-complementing 1 (XRCC1)], have been explored. Cytotoxic effects of TZM associated with PADPRP inhibitors are evident shortly after treatment, suggesting that completion of cell division is not required for the lethal effect of the drug combination. Increase of PADPRP or MPG transcripts was found after treatment with TZM alone or combined with PADPRP inhibitor. XRCC1 transcript was positively modulated only in the case of drug combination. This could suggest that in the presence of PADPRP inhibitor, persistence of DNA damage triggers XRCC1 transcription. Our results suggest that association of TZM and PADPRP inhibitors might be of benefit for MRS-deficient malignancies unresponsive to the methylating agent.

Antineoplastic Agents, Alkylating↗

PubMed1999

Suppression of telomerase, reexpression of KAI1, and abrogation of tumorigenicity by nerve growth factor in prostate cancer cell lines.

Nerve growth factor (NGF) is expressed in the prostate, where it appears to be involved in the control of epithelial cell growth and differentiation. NGF production is decreased in prostate tumors. However, the role of this neurotrophin in the control of proliferation and progression of prostate cancers is still a matter of investigation. Prostate adenocarcinomas are telomerase-positive tumors. Chronic exposure of DU145 and PC3 prostate tumor cell lines to NGF resulted in a dramatic down-regulation of telomerase activity. This effect was correlated in terms of concentrations and time with a remarkable down-regulation of cell proliferation both in vitro and in vivo but was not secondary to NGF-induced quiescence. No down-regulation of telomerase activity was, in fact, detectable during serum starvation-induced quiescence. LNCaP cells, which do not express NGF receptors, appear to be insensitive to the actions of NGF. DU145 and PC3 cells do not express the KAI1 metastasis suppressor gene, which is present in the prostate and is progressively lost during the progression of prostate cancers. Chronic NGF treatment strongly induced the reexpression of this gene in these cell lines, and this effect was correlated with the suppression of their invasive potential in vitro. The data presented here suggest that NGF reverts two metastatic prostate cancer cell lines to slowly proliferating, noninvasive phenotypes characterized by a very low telomerase activity and by the expression of the KAI1 metastasis suppressor gene.

Adenocarcinoma↗

PubMed1999

Suppression of telomerase activity as an indicator of drug-induced cytotoxicity against cancer cells: in vitro studies with fresh human tumor samples.

Telomerase is a ribonucleoprotein complex with reverse-transcriptase activity responsible for telomere reconstitution. High telomerase activity was found in cancer cells, but not in differentiated homologous nonmalignant tissues. We demonstrated previously that the disappearance of telomerase activity is a reliable marker of tumor cell killing in human cancer cell lines. We have investigated the possibility of evaluating chemosensitivity of neoplastic cells of different origin [ovary, lung, breast, gastrointestinal, skin (melanoma)] obtained from cancer patients, by measuring residual telomerase activity after drug treatment in vitro. Using the classical telomeric repeat amplification protocol ("TRAP") assay based on polymerase chain reaction, we examined telomerase activity of untreated or drug-treated tumor cell suspensions, derived from the processing of surgical specimens. Feasibility and reproducibility of the assay were evaluated according to various parameters, including drug concentration, time of in vitro culture, and type of tumor. The results indicated that the assay is highly sensitive and reproducible, and can be performed using surgical specimens in a reasonable percentage of cases, ranging from 40% (breast cancer) to 100% (ovarian cancer). Moreover, the assay provides comparable results using a wide range of tumor cells, and the presence of normal cells does not interfere with the results. Prolonged tumor cell culture is not required because the assay can be completed within 24 to 72 hours after sample collection. In conclusion, the present investigation provides the technical bases for future studies to evaluate whether this assay would be able to predict patient's response to antitumor agents.

Antineoplastic Agents↗

PubMed1999

O(6)-benzylguanine enhances the in vitro immunotoxic activity of temozolomide on natural or antigen-dependent immunity.

Temozolomide (TMZ) is a new cytotoxic triazene compound of clinical interest that is able to generate methyl adducts at the O(6)-guanine of DNA, which can be repaired by O(6)-alkylguanine-DNA alkyltransferase (OGAT). It was previously found that triazene compounds are highly immunosuppressive in mice. In the present study, we investigate whether TMZ could affect immune functions of human competent cells and whether methylation of O(6)-guanine could be involved in the immunosuppressive activity of the drug. Mononuclear cells (MNCs) obtained from peripheral blood of healthy donors were tested for OGAT activity and treated with TMZ alone or combined with the OGAT inhibitor O(6)-benzylguanine. Control or drug-treated MNCs were then assayed for natural killer activity and for the ability to proliferate and to generate cytotoxic effector cells in response to interleukin-2 or allogeneic MT-2 tumor cells. The results show that TMZ inhibited both proliferation and induction of lytic activity in response to interleukin-2 or allogeneic MT-2 cells. Moreover, an inverse correlation was found between the OGAT activity of MNCs and their sensitivity to TMZ. The involvement of O(6)-guanine methylation in the immunosuppressive effects of TMZ was further confirmed by the finding that O(6)-benzylguanine increased the activity of the drug. On the other hand, the natural killer activity of MNCs was only moderately affected by TMZ, and no relationship was observed between OGAT levels and sensitivity to the drug. These data suggest that in patients with tumors who are undergoing TMZ treatment, the drug may impair immune responses involving cell proliferation, depending on OGAT levels of MNCs, and that O(6)-benzylguanine may potentiate this activity.

Antibody-Dependent Cell Cytotoxicity↗

PubMed1998

Interferons antagonize gamma-ray-induced depression of natural immunity.

PURPOSE: The aim of this study was to determine the inhibitory effects of in vitro radiation on the number and function of natural killer (NK) cells and to investigate the capability of interferons (IFNs) to restore the activity of NK, depressed by gamma-rays. METHODS AND MATERIALS: Mononuclear cells (MNC) were obtained from intact or in vitro irradiated (20 Gy) peripheral blood collected from healthy donors. Alternatively, MNC were irradiated (20 Gy) after separation from intact whole blood. The in vitro treatment of MNC with IFNs (alpha, beta, or gamma, 200 UI/ml) was performed at different times after or before radiation. The NK activity (4 h-51Cr release test), the percentage of CD16+/CD56+ cells and apoptosis (cytometric analysis), and binding (microscopic observation) were evaluated on Days 0, 1, 2, and 5 from gamma-ray exposure and IFNs treatment. RESULTS: The in vitro treatment of irradiated MNC with betaIFN after radiation completely reverses the inhibitory effects of gamma-rays on human NK activity. BetaIFN do not reduce the apoptosis induction by radiation and don't modify the number of CD16- or CD56-positive cells. The binding between irradiated effectors and tumor cells (K562) appears partially increased in betaIFN-treated MNC. CONCLUSIONS: The results of the present investigation suggest a possible role of betaIFN in reversing the detrimental effect of radiation on human natural immunity and provide a rational basis for in vivo use of betaIFN in cancer radiotherapy.

Gamma Rays↗

PubMed1998

Adjuvant treatment of breast cancer: a pilot immunochemotherapy study with CMF, interleukin-2 and interferon alpha.

Immune responses, including natural immunity (NI), potentiate the antitumor effects of chemotherapy. Since interferons and interleukin-2 (IL-2) augment NI, a pilot study was conducted to assess the tolerability and the effects on host immunity of adjuvant chemotherapy associated with IL-2 + interferon alpha (IFN) in breast cancer patients after surgery. Ten patients underwent alternating 28-day cycles of chemoimmunotherapy [cyclophosphamide + methotrexate + 5-fluorouracil (CMF, days 1, 8) + IL-2 (days 15 19) + IFN (day 22)] and chemotherapy alone (CMF). With this regimen each patient was considered to be a reasonable "control" of herself. Blood cell count and natural killer cell activity (NKA) were tested on days 1, 8, 15, 22, and 23. Preliminary in vitro studies indicated that IL-2 or IFN antagonized the severe inhibition of NKA induced by hydroxy-peroxy-cyclophosphamide (in vitro active derivative of cyclophosphamide), alone or associated with methotrexate + 5-fluorouracil. Nine patients completed all six alternating cycles, whereas one patient proved to have metastatic lesions after four cycles. The protocol was well tolerated, although leukopenia (CMF alone) and leukopenia with fever and moderate or minimal flu-like symptoms (CMF + IL-2 + IFN) were generally observed. Treatment with IL-2 facilitated complete recovery of white cell counts and NKA after the nadir on day 15. In conclusion, the present protocol appears to be well tolerated and amenable to administration on an outpatient basis. Therefore, further investigations should be performed to verify whether CMF + IL-2 + IFN would be superior to CMF alone for adjuvant treatment after surgery in breast cancer.

Antineoplastic Combined Chemotherapy Protocols↗

PubMed1998

Effect of rifampin on CD1b expression and double-negative T cell responses against mycobacteria-derived glycolipid antigen.

Non-classical antigen-presentation by CD1 molecules expressed on cytokine-activated monocytes (CAM), and cell-mediated responses supported by double-negative (DN) and by CD8+ responder alphabeta T cells, are involved in host resistance against mycobacterial infections. The CD1b protein is responsible for presentation of non-peptide, lipid antigens to T cells. In this context, a pivotal role is played by induction of CD1b protein on the membrane of human monocytes activated by GM-CSF alone, and more efficiently by GM-CSF combined with IL-4. Rifampin (RFP), a drug which is extensively utilized for chemoprophylaxis or treatment of Mycobacterium tuberculosis, is known to reduce a number of B, or T cell-dependent responses. Therefore we undertook immunopharmacological studies on RFP, to determine the effects of this agent on human macrophage function, relative to antigen presentation by CD1b molecules and on DN T cell cytolytic function. The results showed that: (a) graded concentration of RFP (2 or 10 microg/ml) induced a significant increase of CD1b expression, in CAM as evaluated by FACS analysis; (b) RFP increased significantly the specific mAb binding to CD1b on CAM surface; (c) treatment of effector cells with RFP did not reduce DN T cell-mediated cytolysis against lymphoblastoid cells transfected with CD1b cDNA (C1R.b6 cells), pulsed with M. tuberculosis. These results suggest that RFP could be of potential value in improving mycobacterial antigen presentation without impairing responder T cell function.

Antibiotics, Antitubercular↗

PubMed1998

Sensitivity of human melanoma cells to oestrogens, tamoxifen and quercetin: is there any relationship with type I and II oestrogen binding site expression?

We investigated the effect of oestrogens, anti-oestrogens and flavonoids on the growth of a human melanoma cell line (SK-Mel-28) and, at the same time, the presence of both type I oestrogen receptors (ERs) and type II oestrogen binding sites (type II EBS) to gain a fuller picture of the relationship between melanoma cell proliferation and receptor status. 17beta-Oestradiol (E2) and the flavonoid quercetin (Q) produced a marked inhibition of proliferation, but only at the highest dose used (10(-5) M) and only when added daily to the medium. Diethylstilboestrol (DES) (10(-5) M) was effective in inhibiting cell growth when the medium was renewed every 3 days and produced a more pronounced reduction when added daily to the medium. Tamoxifen (TAM) inhibited cell proliferation at a dose starting from 10(-7) M when the medium was renewed every 3 days. When added daily to the medium, it did not induce a greater inhibitory effect and it was cytotoxic at 5 x 10(-6) M and 10(-5) M. The antiproliferative effect of E2, DES and Q did not seem to be dependent on their interaction with ERs, which were minimally detected in SK-Mel-28 in both immunocytochemical and biochemical assays. Our model revealed, through a biochemical assay, a large number of type II EBSs which could be involved in the anti-oestrogen action, but this does not exclude the involvement of other mechanisms. Finally, TAM (10(-5) M) appeared to reduce the activity of the DNA repair enzyme O6-alkylguanine-DNA alkyltransferase, an effect that could be interesting from the point of view of the therapeutic efficacy of alkylating agents.

Anticarcinogenic Agents↗

PubMed1998

Effect of prostaglandin A1 on proliferation and telomerase activity of human melanoma cells in vitro.

Previous studies have shown that cyclopentenone prostaglandins are endowed with antitumour activity in various murine and human tumour models. In the present investigation four human melanoma cell lines were treated with graded concentrations (4-16microg/ml) of prostaglandin A1 (PGA1) for 24 or 48 h in vitro. At the end of the treatment, cell proliferation (measured in terms of DNA synthesis) and telomerase activity were determined. The results showed that PGA1 induced concentration-dependent inhibition of DNA synthesis at 48 h but not at 24 h in SK-MEL-28 cells. In contrast, marked inhibition of telomerase activity was detected after only 24 h of PGA1 treatment. Moreover, after 48h of treatment with the agent, inhibition of telomerase was more pronounced than inhibition of cell proliferation. Additional studies performed with three freshly generated melanoma cell lines confirmed that PGA1 produced early inhibition of cell growth accompanied by marked impairment of telomerase activity. These results suggest that PGA1 could be of potential value as antitumour agent, on the basis of two distinct mechanisms: direct cytostatic/cytotoxic effects on melanoma cells, and inhibitory activity on a tumour-associated enzymatic function (i.e. telomerase) that is responsible for cancer cell immortality.

Cell Division↗

PubMed1998

Involvement of the mismatch repair system in temozolomide-induced apoptosis.

Postreplicative mismatch repair plays a major role in mediating the cytotoxicity of agents generating O6-methylguanine in DNA. We previously showed that a methylating antitumor triazene compound, temozolomide, induces apoptosis and that the persistence of O6-methylguanine in DNA is required to trigger the process. We wanted to test whether the latter apoptotic signal is dependent on a functional mismatch repair system. To this end, we used two human lymphoblastoid cell lines (i.e., the mismatch repair-proficient TK6 line and its mismatch repair-deficient subline MT1) that are both deficient in O6-methylguanine repair. Temozolomide treatment of TK6 cells brought about efficient cell growth inhibition, G2/M arrest, and apoptosis, as indicated by the results of cytofluorimetric analysis of 5-bromo-2'-deoxyuridine incorporation and DNA content and evaluation of DNA fragmentation. The drug treatment resulted also in the induction of p53 and p21/waf-1 protein expression. In contrast, MT1 cells were highly resistant to the drug and no p53 and p21/waf-1 induction was observed. Importantly, we could show that MT1 cells are not deficient in the p53-dependent apoptosis pathway; treatment with etoposide, a topoisomerase II inhibitor, resulted in p53 and p21/waf-1 protein expression and apoptosis in both cell lines. In conclusion, we demonstrate the existence of a link between a functional mismatch repair system and the trigger of apoptosis in cells exposed to clinically relevant concentrations of temozolomide. The results also suggest that p53 induction in response to O6-guanine methylation involves the mismatch repair system.

Antineoplastic Agents, Alkylating↗

PubMed1998

Rifampin increases cytokine-induced expression of the CD1b molecule in human peripheral blood monocytes.

In recent years, it has been shown that a nonclassical, major histocompatibility complex-independent system (i.e., CD1-restricted T-cell responses) is involved in T-cell immunity against nonpeptide antigens. The CD1 system appears to function by presenting microbial lipid antigens to specific T cells, and the antigens so far identified include several known constituents of mycobacterial cell walls. Among the four known human CD1 isoforms, the CD1b protein is the best characterized with regard to its antigen-presenting function. Expression of CD1b is upregulated on human blood monocytes upon exposure to granulocyte/macrophage-colony stimulating factor, alone or in combination with interleukin-4 (IL-4) (S. A. Porcelli, Adv. Immunol. 59:1-98, 1995). Rifampin (RFP) and its derivatives are widely used for chemoprophylaxis or chemotherapy against Mycobacterium tuberculosis. However, this agent was found to reduce the mitogen responsiveness of human B and T lymphocytes, chemotaxis, and delayed-type hypersensitivity. The present study extends the immunopharmacological profile of RFP by examining its effects on CD1b expression by human peripheral blood monocytes exposed to GM-CSF plus IL-4. The results showed that clinically attainable concentrations (i.e., 2 or 10 microg/ml for 24 h) of the agent produced a marked increase in CD1b expression on the plasma membrane, as evaluated by fluorescence-activated cell sorter analysis, whereas it had no effect on cytosolic fractions, as indicated by Western blot analysis. This was found to be the result of increased CD1b gene expression, as shown by Northern blot analysis of CD1b mRNA. These results suggest that RFP could be of potential value in augmenting the CD1b-restricted antigen recognition system, thereby enhancing protective cellular immunity to M. tuberculosis.

Antibiotics, Antitubercular↗

PubMed1998

Role of wild-type p53 on the antineoplastic activity of temozolomide alone or combined with inhibitors of poly(ADP-ribose) polymerase.

The DNA repair enzyme O6-alkylguanine DNA-alkyltransferase (OGAT) and a deficient mismatch repair system play a critical role in the resistance to chemotherapeutic agents that generate adducts at the O6-position of guanine. However, DNA adducts different from O6-methylguanine might be also involved in cytotoxicity induced by methylating agents. Because the loss of p53 function is generally associated with tumor cell resistance to anticancer chemotherapy, we have investigated whether wild-type p53 might affect chemosensitivity of leukemia cells endowed with high OGAT levels to the methylating agent temozolomide (TZM). The effect of poly(ADP-ribose) polymerase (PADPRP) inhibition, which potentiates the cytotoxic effects of N7-methylguanine and N3-methylguanine, was also assessed in OGAT-proficient cells, either susceptible or tolerant to O6-methylguanine. OGAT-proficient and p53 null HL60 cells were transfected with the human p53 cDNA (p53+ cells). Treatment with TZM concentrations not toxic for the cells transduced with the control vector (p53-cells), induced apoptosis in p53+ cells. These cells were characterized by a lower level of bcl-2 protein than p53- cells, whereas bax and OGAT expression was comparable in both lines. Inhibition of PADPRP potentiated the cytotoxic and apoptotic effects of TZM in either p53- or p53+ HL60 cells. Furthermore, PADPRP inhibitors potentiated apoptosis induced by TZM in Jurkat cells, which possess a mutated p53 gene and are tolerant to O6-methylguanine adducts. The analysis of cell cycle indicated that the drug combination of TZM and PADPRP inhibitors provoked G1 arrest only in p53+ cells. Conversely, G1 arrest was not observed in p53+ cells exposed to TZM alone. It is possible to speculate that PADPRP inhibitors might affect the repair of DNA adducts that are processed differently from O6 methylguanine and induce a different pattern of cell cycle distribution. In conclusion, the results show that p53 increases apoptosis by TZM in OGAT-proficient cells and suggest the potential role of PADPRP inhibitors in enhancing TZM activity against leukemias independently of DNA repair systems.

Antineoplastic Agents, Alkylating↗

PubMed1998

Mutation of the mismatch repair gene hMSH2 and hMSH6 in a human T-cell leukemia line tolerant to methylating agents.

Cell killing by monofunctional methylating agents is due mainly to the formation of adducts at the O6 position of guanine. These methyl adducts are removed from DNA by the O6-alkylguanine DNA alkyltransferase (OGAT). The mechanism by which O6-methylguanine (O6meG) induces cell death in OGAT-deficient cells requires a functional mismatch repair system (MRS). We have previously reported that depletion of OGAT activity in the human T-cell leukemic urkat line does not sensitize these cells to the cytotoxic and apoptotic effects of the methylating triazene temozolomide (Tentori et al., 1995). We therefore decided to establish whether the tolerance of Jurkat cells to O6meG could be associated with a defect in MRS. The results of mismatch repair complementation studies indicated that Jurkat cells are defective in hMutSalpha, a heterodimer of the hMSH2 and hMSH6 proteins. Cytogenetic analysis of two Jurkat clones revealed a deletion in the short arm of chromosome region 2p15-21, indicating an allelic loss of both hMSH2 and hMSH6 genes. DNA sequencing revealed that exon 13 of the second hMSH2 allele contains a base substitution at codon 711, which changes an arginine to a termination codon (CGA-->TGA). In addition, a (C)8-->(C)7 frameshift mutation in codon 1085-1087 of the hMSH6 gene was also found. Although both hMSH2 and hMSH6 transcripts could be detected in Jurkat clones, the respective polypeptides were absent. Taken together, these data indicate that tolerance of Jurkat cells to methylation damage is linked to a loss of functional hMutSalpha.

Base Pair Mismatch↗

PubMed1998

Effect of the combined treatment with 5-fluorouracil, gamma-interferon or folinic acid on carcinoembryonic antigen expression in colon cancer cells.

5-Fluorouracil (5-FU) and human recombinant gamma-interferon (gamma-IFN) were found to increase the expression of carcinoembryonic antigen (CEA) in human cancer cells in vitro. In the present study, the antimetabolite was associated with gamma-IFN or folinic acid (FA), a biochemical modulator of cellular metabolism of 5-FU, able to increase its antineoplastic activity. Treatment of two human colon cancer cell lines (HT-29 and WiDr) with 5-FU + gamma-IFN resulted in an increase of CEA expression higher than that obtainable with both agents alone, although no synergistic effects were obtained. This was demonstrated in terms of: (a) mRNA transcripts (HT-29); (b) cytoplasm and membrane CEA protein levels detected by Western blot analysis (HT-29); and (c) plasma membrane reactivity determined by flow cytometry analysis (HT-29 and WiDr). Moreover, 5-FU + gamma-IFN increased HLA class I molecules in the HT-29 cell membrane over that obtainable with gamma-IFN alone. In contrast, both agents did not induce the expression of the costimulatory molecule B7-1. Treatment with FA enhanced the antitumor effect of 5-FU but not its ability to augment CEA expression. This suggests that the FA-sensitive biochemical mechanism of action of 5-FU is not involved in its effect on CEA expression. In vivo studies showed, for the first time, that 5-FU, alone or combined with gamma-IFN, increases the amount of CEA protein over controls, either in cancer cells or in peripheral blood of nude mice bearing HT-29 cells. These results could be of potential diagnostic and/or therapeutic value when CEA protein is the target of humoral or cell-mediated immunity.

Animals↗

PubMed1997

Cytokine-induced expression of CD1b molecules by peripheral blood monocytes: influence of 3'-azido-3'-deoxythymidine.

CD1b is a nonpolymorphic, MHC-like molecule, capable of presenting non-peptide antigens (Ags) to CD3+, CD4-, CD8-, alphabeta or gammadelta T lymphocytes. Previous studies have shown that CD1b can be induced in monocytes/macrophages by GM-CSF+IL-4, and can restrict their presentation of Mycobacterium tuberculosis antigen (Ag) to Ag-specific T cells. Since a number of HIV-positive subjects undergo mycobacterial infections, preliminary studies have been performed to explore whether anti-HIV chemotherapy would influence cytokine-induced CD1b expression in peripheral blood monocytes. The results obtained by treating monocytes with GM-CSF+IL-4, in presence or absence of 3'-azido-3'-deoxythymidine (AZT) showed that: (a) the majority of adherent mononuclear cells (AMNC) collected from peripheral blood of healthy donors, express CD1b molecule on the cell membrane, upon treatment with GM-CSF+IL-4; (b) CD1b appearance is mainly due to the de novo induction of CD1b gene expression (as confirmed by Northern blot analysis), rather than to migration of the molecule from the cytoplasm to the plasma membrane (as suggested by Western blot analysis); (c) AZT does not alter the percentage of CD1b+ AMNC treated with the cytokines; (d) however, AZT inhibits cytokine-induced proliferation of AMNC, thus reducing the overall Ag-presenting potential of the host. Our results suggest that the anti-proliferative effect of AZT could depress anti-mycobacteria immunity in AZT-treated subjects, which may have important implication for the clinical outcome of patients harbouring inadequately treated mycobacterial infections.

Anti-HIV Agents↗

PubMed1997

In vitro antitumor activity of 3'-desamino-3'(2-methoxy-4-morpholinyl) doxorubicin on human melanoma cells sensitive or resistant to triazene compounds.

A new methoxymorpholinyl derivative of Adriamycin (ADR), FCE 23762 (MRD), has recently been selected for phase I clinical trials for its reduced cardiotoxicity and for its cytotoxic activity against a broad spectrum of solid tumors and leukemias that are sensitive or resistant to ADR. The purpose of the present study was to compare the in vitro antitumor activity of MRD and ADR on human melanoma lines with different chemosensitivity to triazene compounds, among which dacarbazine remains a reference drug in the treatment of melanoma. Both MRD and ADR were tested in vitro on three melanoma lines, MI13443-MEL, SK-MEL-28, and M14, previously screened for their chemosensitivity to the triazene compound p-(3-methyl-1-triazeno) benzoic acid, potassium salt (MTBA). The three lines were also analyzed for P-170 expression, total glutathione (GSH) content, and GSH-related enzyme activity. All melanomas, whether sensitive or resistant to MTBA, were susceptible to anthracycline treatment. The cytotoxic activity of MRD was comparable with that of ADR, and no substantial difference was found in cell growth inhibition between the two drugs. When the relative chemosensitivity of the three lines was considered, SK-MEL-28 was found to be slightly less sensitive to MRD treatment than the other tumors. This finding seems to correlate with the higher GSH-peroxidase activity of this melanoma relative to that of the MI13443 and M14 lines. These results show a homogeneous response of melanoma lines to MRD treatment in vitro, suggesting that phase I clinical trials concerning this drug, which in vivo appears to be activated to a more cytotoxic metabolite, could be extended to metastatic melanomas, including those completely resistant to triazene compounds.

ATP Binding Cassette Transporter, Subfamily B, Mem↗

PubMed1997

AZT inhibits the transmission of human T cell leukaemia/lymphoma virus type I to adult peripheral blood mononuclear cells in vitro.

The effect of 3'-azido-3'-deoxythymidine (AZT) on in vitro infection of peripheral blood mononuclear cells (PBMCs) isolated from normal adult individuals with human T cell leukaemia/lymphoma virus type I (HTLV-I) was evaluated. Different PBMC samples were exposed to HTLV-I by cocultivation with MT-2 (a chronically infected cell line) in the presence of 20 U/ml of human recombinant interleukin 2 (IL-2) and graded concentrations of AZT. Control and drug-treated cultures, of both infected and uninfected PBMCs, were then grown for several weeks and monitored for virological and immunological parameters. The results showed a concentration-dependent anti-proliferative effect of AZT in both infected and non-infected cultures. Production of both proviral DNA and viral RNA was inhibited not only at the higher concentrations of AZT (8 microM and 32 microM) but also at concentrations as low as 0.1-2 microM. These results were confirmed by PCR and by flow cytometry analysis for the viral core protein p19. Moreover, treatment with AZT resulted in a decreased expression of CD25 in cultures exposed to HTLV-I as well as in non-infected PBMCs. On the other hand, HLA-DR was down-regulated to a greater extent in drug-treated, virus-exposed cultures in comparison with those not infected. No evidence of the antiviral activity of AZT was observed in PBMC cultures already infected by HTLV-I or in MT-2 cells. These findings demonstrate that treatment with AZT, when given at the time of infection with HTLV-I, has a marked protective effect on PBMCs.

Adult↗