PubMed Health⌕ Search

Biomedical subjects

C Leonetti

Publications and source records attributed to C Leonetti.

33 records · Page 2Linked to original sources
PubMed1995

Antitumor and antimetastatic effects of dacarbazine combined with cyclophosphamide and interleukin-2 in Lewis lung carcinoma (3LL).

The antitumor and antimetastatic activity of dacarbazine (DTIC) alone or in combination with cyclophosphamide (CY) was tested in C57BL/6 mice bearing Lewis lung carcinoma (3LL). Treatment with both agents significantly reduced tumor growth and the number of metastases. These effects were associated with marked changes of the biochemical and immunological properties of drug-treated 3LL cells, i.e. (a) reduction of alpha 6 integrin expression, (b) increased susceptibility to natural immunity in vivo, as measured in terms of rapid clearance from mouse lungs of prelabeled 3LL cells injected i.v. and (c) increased immunogenicity, as assessed by T-cell-mediated immune responses (i.e. graft rejection by intact syngeneic mice, and frequency of specific CTL precursors recognizing DTIC/CY-treated cancer cells). The immunotherapeutic advantage afforded by increased immunosensitivity and immunogenicity of 3LL cells exposed to DTIC + CY appears to be markedly reduced in vivo by the profound immunodepressive effects of these drugs. Within this context, addition of interleukin-2 was found to increase the antitumor and antimetastatic activity of this chemotherapeutic regimen. The present study shows, for the first time in a solid tumor model, that a biological response modifier increases the antitumor efficacy of drugs that are able to affect the immunological properties of cancer cells.

Animals↗
PubMed1995

Temozolomide reduces the metastatic potential of Lewis lung carcinoma (3LL) in mice: role of alpha-6 integrin phosphorylation.

The involvement of protein kinase c (PKC) in the mechanism underlying the antimetastatic properties of triazenes was studied in C57BL/6 mice bearing Lewis lung carcinoma (3LL). In vivo and in vitro treatment with temozolomide, an in-vitro active analogue of dacarbazine, or calphostin c produced a concentration-dependent reduction of spontaneous and artificial metastases. Both agents reduced the ability of 3LL cells to adhere to endothelium. Diethylaminoethyl (DEAE)-sepharose chromatography of cell extracts revealed that incubation of 3LL cells with 12-O-tetradecanoylphorbol-13-acetate (TPA) caused a rapid translocation of protein kinase c activity from cytosol to the membrane fraction. Membrane PKC activity induced by TPA was reduced by 60% after treatment with temozolomide. Coincident with these changes, TPA induced phosphorylation of alpha-6 integrin, whereas temozolomide or calphostin c abolished the appearance of this phosphoprotein. These results suggest that temozolomide reduced metastatic potential by interfering with alpha-6 phosphorylation induced by PKC activation.

Animals↗
PubMed1992

Pharmacological purging of syngeneic bone marrow ex vivo: effect of treatment with doxorubicin and lonidamine on normal and leukaemic cells of DBA/2 mice.

The in vivo effect of in vitro treatment with doxorubicin plus lonidamine on normal and leukaemic cells was investigated in a mouse model of syngeneic bone marrow transplantation. Different numbers of L5178Y tumour cells or normal bone marrow cells alone, or mixtures of bone marrow and leukaemic cells were incubated with doxorubicin (0.25, 0.5, 0.75, 1 microgram/ml) and/or lonidamine (50 micrograms/ml) and reinfused in DBA/2 mice. Lonidamine potentiated the cytotoxic effect of doxorubicin dependent on doxorubicin dosage and tumour cell concentration. Survival after injection of 10(4) in vitro-treated tumour cells was 42% for doxorubicin 0.75 micrograms/ml alone versus 100% for the combination with lonidamine and 50% for doxorubicin 1 microgram/ml alone versus 100% combination. Reinfusion of normal bone marrow incubated with doxorubicin alone or in combination with lonidamine in lethally irradiated mice did not occur in 12-14% of mice injected, indicating that the repopulating ability of stem cells was spared. These data suggest the potential usefulness of lonidamine in ex vivo purging of bone marrow before autologous bone marrow transplants in haemopoietic malignancies.

Animals↗
PubMed1992

N-methylformamide effects on cell proliferation and antigenic pattern in HT-29 colon carcinoma cell line.

The effects of the differentiating agent N-methylformamide (NMF) on cell proliferation and antigenic pattern of HT-29 colon carcinoma cells have been investigated. The cell line was cultured in the presence, or absence, of 1% NMF and tested for the above mentioned characteristics, both in vitro and after injection into nude mice. The percentage of cells in the various cell cycle compartments was estimated by flow cytometry. The presentation on the cell surface of molecules such as tumour associated antigens (TAAs), HLA class I molecules and epidermal growth factor receptor (EGF-R) was analysed by ELISA, flow cytometry and immunohistochemistry. Results demonstrate that NMF impairs HT-29 cell proliferation with a remarkable accumulation in the G0/G1 phases, as well as inducing a modification of the membrane antigenic pattern. The presence of NMF in the culture medium decreases the TAAs and EGF-R whereas HLA antigen maintains the same level of positivity in the two cell lines. These alterations are consistent with a different behaviour in vivo of the tumours originated from NMF treated and untreated cells. Tumours derived from NMF treated cells show a delay in the appearance and low levels of immunodetectable carcinoembryonic antigen (CEA) molecules.

Animals↗
PubMed1991

Different effects of sequential combinations of N-methylformamide with 5-fluorouracil on human colon carcinoma cells growing in nude mice.

The effects of the combination of N-methylformamide (NMF) with 5-fluorouracil (5-FU) on tumor growth and morphological features of human colon carcinoma cells (HT29) implanted in nude mice were assessed. Both agents were administered i.p. at tolerable doses: 5-FU at 19 mg/kg for 5 days and NMF at 200 mg/kg for 12 days. Four main schedules were tested: 5-FU alone, NMF alone, NMF followed by 5-FU and 5-FU followed by NMF. The last sequence was the most effective, as compared with the other treatment regimens. In particular, the 5-FU----NMF combination induced a tumor inhibition of about 75% at the end of the treatments (17th day) versus an inhibition of 23%-43% in the other schedules. Morphological observations, carried out by light and electron microscopy, indicated a possible relationship between the presence of structural changes and tumor growth inhibition. The results of this study renew interest in the use of NMF in sequential combination confirming sequence as a critical factor for the optimal combination of NMF and 5-FU.

Adenocarcinoma↗
PubMed1991

Cerebral blood flow in AIDS-related neurotoxoplasmosis: a preliminary 99mTc-HMPAO SPECT study.

Cerebral blood flow (CBF) was evaluated by gamma camera 99mTc-HMPAO SPECT in 11 patients with AIDS-related neurotoxoplasmosis and correlated with neurological findings and the results of CT and MRI. Evident CBF abnormalities were observed in all patients with involvement of at least two cerebral lobes. In 10 patients the abnormalities were bilateral and in 8 patients basal ganglia were involved; no specific hypoperfusion pattern was however evident. Focal lesions were found in 7 patients by CT (sensitivity: 63.6%) and in 10 patients by MRI (sensitivity: 90.9%). It may be concluded that neurotoxoplasmosis in AIDS patients is associated with a high prevalence of focal cortical and subcortical hypoperfusion but that the scintigraphic findings are not specific; that HMPAO SPECT may show focal hypoperfusion in patients with normal CT studies and/or non-focal MRI abnormalities; that the hypoperfusion may be more extensive than the corresponding MRI lesion(s) and that it may be present even in areas with normal MRI signals; and that more experience and longitudinal studies are needed to assess the possible impact of HMPAO SPECT on follow-up and therapy monitoring.

Acquired Immunodeficiency Syndrome↗
PubMed1990

IL-2 reverses the inhibition of cytotoxic T-cell responses induced by 5-(3,3' dimethyl-1-triazeno)-imidazole-4-carboxamide (DTIC) in vitro.

One of the major limitations in the use of triazene compounds for inducing increased immunogenicity of tumor cells in vivo (i.e. chemical xenogenization) is the profound immunodepressive activity of these drugs. The present study analysed the inhibitory effects of DTIC on various T-dependent immune responses in mice in an attempt to determine the mechanism of action and appropriate treatments for reverting the immune damage produced by the agent. Results obtained show that treatment with DTIC in vivo produced: (a) inhibition of spleen cell proliferation; (b) reduced IL-2 production in response to allogeneic stimuli; (c) reduction of the generation of IL-2R + CD8 + cells in allogeneic MLC; (d) inhibition of allo-CTL generation. The addition of IL-2 to MLC on day 2 of the co-culture restored full allogeneic CTL responses. These data suggest that exogenous IL-2 could be used to counteract DTIC-induced depression of T-cell reactivity, which is presumably involved in hosts' responses against autochthonous xenogenized tumor cells.

Animals↗
PubMed1990

Synergism between 5-fluorouracil and N-methylformamide in HT29 human colon cancer line.

In HT29 cells 5-fluorouracil (5FU) cytotoxicity is enhanced by subsequent incubation of cells in medium containing 1% N-methylformamide (NMF). This enhancement does not appear to be related to differences in the repair of 5FU-induced DNA damage. It is proposed that the inhibition of DNA synthesis by NMF (that is reversible and does not result in any detectable toxicity) becomes a lethal event in a cell in which DNA synthesis has already been altered by 5FU exposure. The synergism is sequence dependent (i.e. it does not occur when NMF is given before 5FU) and specific for some cell types as shown by the fact that no synergism was found in L1210 mouse leukaemia cells. In nude mice transplanted s.c. with HT29 cells daily 5FU treatment (for 5 days) followed by daily NMF treatment (for 10 days) caused much greater inhibition of tumour growth than either drug alone or the same combination given in the opposite order (NMF then 5FU). These results, if confirmed on other human colon tumours, could be of clinical interest as a means of increasing the therapeutic efficacy of 5FU in patients with colon cancer.

Adenocarcinoma↗
PubMedDate not supplied

Bcl-2 overexpression decreases BCNU sensitivity of a human glioblastoma line through enhancement of catalase activity.

The aim of this study was to evaluate the role of bcl-2 in 1,3-bis(2-chloroethyl)-1-nitrosourea (BCNU) sensitivity of the ADFS human glioblastoma cell line in vitro and in vivo. To this end, the ADFS line expressing a low level of the bcl-2 protein was transfected with a bcl-2 expression vector. We found that bcl-2 overexpressing clones were less sensitive to in vitro BCNU treatment than the control clone. Cell cycle analysis demonstrated that while BCNU induced a consistent block in S/G2-M phases of the cell cycle in the control clone, it did not affect the cell cycle phase distribution of the two bcl-2 transfectants. The different sensitivity to BCNU was unrelated to the ability of bcl-2 to inhibit apoptosis, while bcl-2 appeared to protect bcl-2 transfectants from BCNU toxicity through an increase of catalase activity. The ability of the catalase inhibitor, sodium azide, to increase the BCNU sensitivity of the bcl-2 transfectants to levels of the BCNU-treated control clone substantiated the role of the catalase activity. The effect of bcl-2 in reducing sensitivity to BCNU was also confirmed by in vivo experiments. Xenografts of bcl-2 overexpressing tumors were less sensitive to BCNU treatment than xenografts originating from control cells.

Animals↗
PubMedDate not supplied

Comparative in vitro and in vivo study of a nitroxyl derivative of 5-fluorouracil (magnizil) on human gastrointestinal tumors.

AIMS AND BACKGROUND: There is much interest in nitroxyl derivatives of cytotoxic agents. We evaluated the potential activity of magnizil, a derivative of 5-fluorouracil, on human gastrointestinal tumors in 3 different in vitro and in vivo experimental models. METHODS: The activities of magnizil and 5-fluorouracil were comparatively determined in vitro on the HT29 cell line by a clonogenic assay and on tumor clinical specimens by an antimetabolic assay. The activity of both the drugs against human tumors was also assessed in mice with the subrenal capsule assay. RESULTS: A similar cytotoxic activity was found for magnizil and 5-fluorouracil on the HT29 cell line. As regards human tumors, a lower activity was observed for the nitroxyl derivative than for 5-fluorouracil, with response rates of 25% and 50%, respectively, at comparable concentrations. Moreover, among the tumors transplanted in the subrenal capsule of mice, two were sensitive to magnizil and 3 to 5-fluorouracil. CONCLUSIONS: Even though experimental results on human tumors indicate a somewhat lower activity for magnizil than the parent compound, its low toxicity and the possibility to clinically use high doses suggest the opportunity to further investigate the potential of this new anticancer agent on larger series of colorectal cancers in experimental systems.

Animals↗
PubMedDate not supplied

[Buschke Scleredema, case report].

Buschke Scleredema is a rare connective tissue disorder of unknown aetiology, characterized by thickening of the dermis whose characteristics may mainly to mime systemic sclerosis, eosinophilic fasciitis and cutaneous amyloidosis. Scleredema may be associated with a history of an antecedent febrile illness, diabetes mellitus, or blood dyscrasia. Scleredema can be classified into three clinical groups; each has a different history, course, and prognosis. Each one of these share reduction in chest articular movements and limitation of limbs movements. The skin histology is characterised by thickened dermis and increased spaces between large collagen bundles due to increased deposition of mucopolysaccharide in the dermis. Differential diagnosis can be made considering the typical clinical features and the histologic peculiarity. No therapy has been found effective. The authors describe a case of Buschke Scleredema successfully treated by steroids and colchicine. Clinical evaluation of skin induration and thickness as well as ultrasonography were performed at baseline and after treatment.

Adrenal Cortex Hormones↗
PubMedDate not supplied

[The use of continuous cell cultures for the study of tumor heterogeneity and drug sensitivity].

Intratumoral heterogeneity was observed in two tumor lines (SbC11 and SbC12) derived from a single biopsy of a melanoma patient. Differences in drug sensitivity were observed in three cell lines of small cell lung carcinoma derived from the same patient, before (AE1), and after (AE2 and AE3) therapy with Adriamycin (ADM) and Cisplatinum (DDP). Moreover, heterogeneity in biological features and in drug sensitivity was observed in three continuous human glioma derived cell lines (LI, DF, and DP). The results show the importance of continuous cell lines for studying tumor heterogeneity and evaluating the effectiveness of antineoplastic agents.

Carcinoma, Small Cell↗
PubMedDate not supplied

Schedule-dependent effectiveness of ADM and multiple cycles of DDP on a murine reticulum sarcoma.

The therapeutic index of adriamycin (ADM) and cisplatin (DDP) combination versus repeated sequences of the more active drug (DDP) was investigated on a murine reticulum cell sarcoma of ovarian origin (M5) implanted i.m. in C57BL/6 mice. The antitumor efficacy of multiple cycles of DDP according to different regimens at a prefixed time (every 7 days) or at tumor regrowth was also evaluated. Our data demonstrate that the ADM-DDP combination did not improve the antitumoral efficacy of DDP as single agent, while repeated cycles of DDP led to a significant increase in the host life span. Differences in therapeutic effect were elicited by the two schedules: the regimen at a prefixed time showed a major effect on local tumor control, although the regimen at tumor regrowth was better tolerated.

Animals↗
PubMedDate not supplied

Human glioma lines as experimental model for biological and chemosensitivity studies.

The use of rodent tumor lines is no longer satisfactory for either biological and chemosensitivity studies because of their well demonstrated difference in behaviour when compared to human tumors. With the employment of human tumor cell lines, both in vitro and in vivo, in nude mice, it is now possible to utilize an extremely more reliable model system able to specifically evaluate many biological features of human tumors as well as their chemosensitivity. Particularly, glioma-derived human tumor lines which grow both in vitro and in nude mice, allowed to assess several parameters able to indicate new therapeutic strategies.

Animals↗