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.

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.

Transferrin-Targeted Nanoparticles Containing Zoledronic Acid as a Potential Tool to Inhibit Glioblastoma Growth

The treatment of glioblastoma (GBM) is a challenge for the biomedical research since cures remain elusive. Its current therapy, consisted on surgery, radiotherapy, and concomitant chemotherapy with temozolomide (TMZ), is often uneffective. Here, we proposed the use of zoledronic acid (ZOL) as a potential agent for the treatment of GBM. Our group previously developed self-assembling nanoparticles, also named PLCaPZ NPs, to use ZOL in the treatment of prostate cancer. Here, we updated the previously developed nanoparticles (NPs) by designing transferrin (Tf)-targeted self-assembling NPs, also named Tf-PLCaPZ NPs, to use ZOL in the treatment of brain tumors, e.g., GBM. The efficacy of Tf-PLCaPZ NPs was evaluated in different GBM cell lines and in an animal model of GBM, in comparison with PLCaPZ NPs and free ZOL. Tf-PLCaPZ NPs were characterized by a narrow size distribution and a high incorporation efficiency of ZOL. Moreover, the presence of Tf significantly reduced the hemolytic activity of the formulation. In vitro, in LN229 cells, a significant uptake and cell growth inhibition after treatment with Tf-PLCaPZ NPs was achieved. Moreover, the sequential therapy of TMZ and Tf-PLCaPZ NPs lead to a superior therapeutic activity compared to their single administration. The results obtained in mice xenografted with U373MG, revealed a significant anticancer activity of Tf-PLCaPZ NPs, while the tumors remained unaffected with free TMZ. These promising results introduce a novel type of easy-to-obtain NPs for the delivery of ZOL in the treatment of GBM tumors.

Targeted therapy for brain tumours: role of PARP inhibitors

The prognosis of malignant glioma and metastatic brain tumours is still extremely poor, despite recent advances in therapeutic strategies with molecular-targeted agents. Poly(ADP-ribose) polymerase (PARP) inhibitors are a promising, novel class of anticancer drugs to be used either as single agents or in combination with chemotherapy and radiotherapy. PARP-1 and PARP-2 are the only PARP proteins that bind to DNA single strand breaks (SSBs), facilitating the repair process by the base excision repair. For this reason, PARPs have been extensively investigated as targets of novel drugs that may be used to enhance the antitumour activity of SSBs inducing agents, such as the methylating compound temozolomide, which is the drug of choice for glioblastoma, or ionizing radiations. Moreover, PARP inhibitors exert cytotoxic effects in monotherapy in BRCA mutated tumours, which are defective in the homologous recombination (HR) repair. Finally, recent studies have shown that inhibition of PARP function might also induce anti-angiogenic effects which might contribute to impair tumour growth. Many clinical trials with PARP inhibitors are ongoing for the treatment of a variety of advanced solid tumours, including primary or secondary brain tumours. This review discusses the implications of targeting PARP on the design of new treatment regimens.

Pharmacological inhibition of poly(ADP-ribose) polymerase (PARP) activity in PARP-1 silenced tumour cells increases chemosensitivity to temozolomide and to a N3-adenine selective methylating agent

We recently demonstrated that poly(ADP-ribose) polymerase (PARP)-1 is involved in angiogenesis and tumour aggressiveness. In this study we have compared the influence of abrogation of PARP-1 expression by stable gene silencing to that of the pharmacological inhibition of cellular PARP activity using PARP-1/-2 inhibitors on the chemosensitivity of tumour cells to the wide spectrum methylating agent temozolomide (TMZ) and to the N3-adenine selective methylating agent {1-methyl-4-[1-methyl-4-(3-methoxysulfonylpropanamido)pyrrole-2-carboxamido]-pyrrole-2-carboxamido}propane (Me-Lex). Silencing of PARP-1 in melanoma or cervical carcinoma lines enhanced in vitro sensitivity to TMZ and Me- Lex, and induced a higher level of cell accumulation at the G2/M phase of cell cycle with respect to controls. GPI 15427, which inhibits both PARP-1 and PARP-2, increased sensitivity to TMZ and Me-Lex both in PARP-1-proficient and - deficient cells. However, it induced different cell cycle modulations depending on PARP-1 expression, provoking a G2/M arrest only in PARP-1 silenced cells. Treatment of PARP-1 silenced cells with TMZ or Me-Lex resulted in a more extensive phosphorylation of Chk-1 and p53 as compared to PARP-1 proficient cells. The combination of the methylating agents with GPI 15427 increased Chk-1 and p53 phosphorylation both in PARP-1 proficient or deficient cells. When mice challenged with PARP-1 silenced melanoma cells were treated with the TMZ and PARP inhibitor combination there was an additional reduction in tumour growth with respect to treatment with TMZ alone. These results suggest the involvement of PARP-2 or other PARPs, in the repair of DNA damage provoked by methylating agents, highlighting the importance of targeting both PARP-1 and PARP-2 for cancer therapy.

[Recurrent new-onset uveitis in a patient with rheumatoid arthritis during anti-TNFalpha treatment]

Inflammation involving the uveal tract of the eye, termed uveitis, is frequently associated with various rheumatic disease, including seronegative spondylarthropathies, juvenile rheumatoid arthritis, Crohn's disease and Behçet's disease. Scleritis and keratitis may be associated with rheumatoid arthritis and systemic vasculitides such as Wegener's granulomatosis. Immune-mediated uveitis can have a chronic relapsing course and produce numerous possible complications, many of which can result in permanent vision loss. Treatment typically includes topical or systemic corticosteroids with cycloplegic-mydriatic drugs and/or noncorticosteroid immunosuppressants, but often there is an insufficient clinical effectiveness. Anti-TNFalpha therapy is promising in the treatment of sight threatening uveitis, particularly in patients with Behçet's disease. However, there have been also reports of new-onset uveitis during treatment of joint disease with TNFalpha inhibitors. We describe a case of new-onset uveitis in a patient with rheumatoid arthritis during therapy with etanercept at first and infliximab at last. Although we cannot exclude uveitis as linked to rheumatoid arthritis, it is unlike that the uveitis arises when the joint disease is well controlled. The hypothetical paradoxical effect of anti-TNF is here discussed.

Targeting different signaling pathways with antisense oligonucleotides combination for cancer therapy

The evidence that cancer development is a complex and multistep process, characterized by alterations of genes involved in the regulation of proliferation, apoptosis and angiogenesis, has led to development of new therapeutic strategies based on the use of agents able to selectively inhibit key molecules of these pathways. In particular, antisense oligonucleotides (ASOs) have proved their efficacy as targeted therapy in preclinical studies, have been well tolerated and able to modulate target protein expression in clinical studies. Although these agents have shown considerable promise for antitumoral therapy, treatment with ASOs used as single agent does not seem particularly promising because of the multigenic alterations of tumors. Based on these considerations, approaches based on the combination of ASOs targeting oncogenes involved in different molecular pathways have been investigated. Moreover, the role of this novel strategy when integrated with conventional drugs or signaling inhibitors, has been assessed. This review addresses some advances in the ASOs combination and reports the potential application of this strategy for the treatment of human cancer.

[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.

High activity of salvage treatment with biweekly paclitaxel-gemcitabine combination in heavily pretreated breast cancer patients

The treatment of refractory metastatic breast cancer is primarily palliative, without a significant impact on overall survival. Among the innovative combinations in this unfavourable setting, paclitaxel and gemcitabine showed a possible synergistic action and an encouraging activity in some clinical trials. This phase II study was carried out to evaluate paclitaxel-gemcitabine combination in very heavily pretreated advanced breast cancer on a bi-weekly schedule.Thirty-nine women with advanced breast cancer were treated with paclitaxel 150 mg/m2 as 3 hrs infusion, and gemcitabine 1,500 mg/m2 as 30 mins infusion, both drugs administered on days 1, 15, with cycles repeated every 28 days. All but two patients received granulocyte colony stimulating factor (G-CSF) on days 7 to 9 and 20 to 22 of every cycle. More than two third (71%) of the patients had previously received two or more chemotherapy regimens for advanced disease, including almost all active agents in this disease. Objective responses were observed in 18 out of 34 evaluable patients (53%; 95% CI, 36% to 70%). Disease remained stable in 7 patients (21%). Responses by sites were 67% in soft tissue and in bone, and 48% in visceral disease. Median time to progression and overall survival were 9 and 20 months, respectively. Treatment was well tolerated, with G3-4 neutropenia in 8%, and G 1-2 thrombocytopenia in 13% of the patients; non-hematological toxicities were mild, with G3 hepatotoxicity in 5% of the patients, and G3 peripheral neurotoxicity in 10% of the patients. Biweekly paclitaxel/gemcitabine combination with G-CSF support appears to be very active as salvage therapy in heavily pretreated breast cancer patients, with a very favourable safety profile.

Supplementation of L-arginine prevents glucocorticoid-induced reduction of bone growth and bone turnover abnormalities in a growing rat model

The present study was designed to evaluate the effects of glucocorticoid (GC) treatment on bone turnover and bone mineral density in the growing rat. Because of the recent evidence that nitric oxide (NO) can counteract prednisolone-induced bone loss in mature rats, we examined the effect on bone of the NO donor L: -arginine in young male rats, in which bone mass is increased by the same biological mechanism as in children and adolescents. Thirty-six 10-week-old Sprague-Dawley male rats were assigned to six groups of six animals each, and treated for 4 weeks with either vehicle (once a week subcutaneous injection of 100 microl of sesame oil); prednisolone sodium succinate, 5 mg/kg, 5 days per week by intramuscular injection (i.m.); L-arginine, 10 mg/kg intraperitoneally (i.p.) once a day; N(G)-nitro-L-arginine methylester (L-NAME), 50 mg/kg subcutaneously once a day; prednisolone sodium succinate 5 mg/kg, 5 days per week i.m. +L-arginine 10 mg/kg i.p. once a day; or prednisolone sodium succinate, 5 mg/kg, 5 days per week i.m. +L-NAME 50 mg/kg subcutaneously once a day. Serum calcium, alkaline phosphatase (ALP), osteocalcin, and the C-terminal telopeptides of type I collagen (RatLaps) were measured at baseline conditions and after 2 and 4 weeks. Prior to treatment, and after 2 and 4 weeks, the whole body, vertebral, pelvic, and femoral bone mineral density (BMD) was measured by dual-energy X-ray absorptiometry (DXA) scanning. Prednisolone and prednisolone+L-NAME treated rats had significantly lower ALP and osteocalcin levels than controls at 2 and 4 weeks, and significantly higher levels of Rat-Laps than controls at 4 weeks. Prednisolone, L-NAME, and prednisolone+L-NAME produced a significant inhibition of bone accumulation and bone growth at all sites measured. Supplementation with L-arginine appeared to prevent the inhibition of bone growth and increase in bone resorption induced by prednisolone. These data would suggest, for the first time, that supplementation with an NO donor could be considered as a treatment for steroid-induced osteoporosis in the developing skeleton.

A role for c-myc in DNA damage-induced apoptosis in a human TP53-mutant small-cell lung cancer cell line

Based on the role of p53 in the control of apoptosis following DNA damage, the status of the TP53 gene has been implicated as a major determinant of tumour responsiveness to cytotoxic therapies. In spite of the high frequency of TP53 mutations, small-cell lung cancer (SCLC) is recognised as one of the most chemoresponsive solid tumours. Since the relevance of the TP53 gene status in the modulation of tumour responsiveness is dependent on the molecular/biological context, in the present study, we have examined the relationship between chemosensitivity and susceptibility to apoptosis of a TP53-mutant human SCLC cell line. The cell line, in spite of TP53 mutation, retained an efficient response to genotoxic stress as documented by cells ability to modulate the p53 protein, arrest in the G1 and G2 phases of the cell cycle and its marked susceptibility to apoptosis following treatment with DNA damaging agents. Exposure to DNA-damaging agents caused an increase of c-Myc, a DNA damage-responsive transcription factor. An analysis of damage-induced apoptosis in the presence of an anti-Fas/CD95 inhibitory antibody indicated that Fas/CD95 was not required for the apoptotic response. The results support an implication of c-myc in sensitising cells to apoptosis, since inhibition of c-Myc expression with an antisense oligodeoxynucleotide (AS-ODN) almost abolished the drug-induced apoptotic response. In conclusion, the present results support a role for c-myc in the induction of apoptosis by genotoxic stress in the absence of a functional p53 and provide new insights into the mechanisms that may influence apoptosis in TP53-mutant cells. Elucidation of this pathway and of the possible cooperation with p53-dependent mechanisms may provide a basis for therapeutic intervention.

In vitro and in vivo inhibition of SK-N-MC neuroblastoma growth using cyclic nucleotide phosphodiesterase inhibitors

The effect of cyclic nucleotide phosphodiesterase (PDE) inhibitors Zaprinast and DC-TA-46 has been tested on SK-N-MC neuroblastoma growth. Antiproliferative activity of the tested drugs was assayed both in vitro and in the xenograft model of nude mice. In clonal density experiments, the IC50 value was 3.3 microM for Zaprinast and 1.9 microM for DC-TA-46, while 7.5 microM BCNU alkylating agent was required to obtain the same effect. SK-N-MC cells xenografted in the nude mouse showed that the administration of Zaprinast and DC-TA-46 caused a significant 50% decrease of the tumour weight. These data demonstrate that PDE inhibitors may be useful for at least reducing tumour growth; they may be of interest for further evaluation as alternative molecules in the design of multiple agent protocols for neuroblastoma treatment.

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.

Encapsulation of c-myc antisense oligodeoxynucleotides in lipid particles improves antitumoral efficacy in vivo in a human melanoma line

Phosphorothioate c-myc antisense oligodeoxynucleotides [S]ODNs (free INX-6295) were encapsulated in a new liposome formulation and the antitumor activity was compared to the unencapsulated antisense in a human melanoma xenograft. The systemic administration of INX-6295 encapsulated in stabilized antisense lipid particles (SALP INX-6295) improved plasma AUC (area under the plasma concentration-time curve) and initial half-life of free INX-6295, resulting in a significant enhancement in tumor accumulation and improvement in tumor distribution of antisense oligodeoxynucleotides. Animals treated with SALP INX-6295 exhibited a prolonged reduction of c-myc expression, reduced tumor growth and increased mice survival. When administered in combination with cisplatin (DDP), SALP INX-6295 produced a complete tumor regression in approximately 30% of treated mice, which persisted for at least 60 days following the first cycle of treatment. Finally, the median survival of mice treated with DDP/SALP INX-6295 increased by 105% compared to 84% for animals treated with the combination DDP/free INX-6295. These data indicate that the biological activity and the therapeutic efficacy of c-myc antisense therapy may be improved when these agents are administered in lipid-based delivery systems.

Increased TGFbeta type II receptor expression suppresses the malignant phenotype and induces differentiation of human neuroblastoma cells

TGFbeta can modulate neuroblastoma (NB) cell proliferation and differentiation in vitro. In this study we used a NB cell line (LAN-5) which has been shown to partially respond to TGFbeta and to present high levels of TGFbeta receptor type I and low levels of receptor type II (TbetaRII) on the cell surface. To evaluate the role of TbetaRII in mediating TGFbeta effects, LAN-5 cells were transfected with an expression vector containing the human full-length TbetaRII cDNA or with the empty vector pcDNA3. Compared to control CLV3 cells (transfected with empty plasmid) and parental LAN-5 cells, isolated neomycin-resistant clones (CL1 and CL3) expressed higher levels of TbetaRII, had reduced cell growth rate in vitro, and were unable to form tumors in vivo. Furthermore, isolated clones modified their morphology, assuming a terminally differentiated neuronal phenotype. Immunocytochemical staining demonstrated a basal increased expression of neural-specific markers, such as axonal growth-associated protein (GAP43) and neurofilaments (NF200). TGFbeta treatment further increased the synthesis of NF200 and GAP43 in the transfected clones as revealed by Western blot analysis. These data indicate that TbetaRII overexpression potentiates the TGFbeta signal transduction pathway, reverting NB cell neoplastic phenotype with the reduction of proliferation rate and the induction of terminal maturation.

Sensitivity to DNA cross-linking chemotherapeutic agents in mismatch repair-defective cells in vitro and in xenografts

Together with tolerance to killing induced by methylating agents, loss of mismatch repair (MMR) has previously been found to be associated with hypersensitivity to the DNAcross-linking agent 1-(2-chloroethyl)-3-cyclohexyl-nitrosourea(CCNU) in several human tumor cell lines (Aquilina et al., 1998). Here, we have investigated whether MMR might act as an efficient repair pathway and provide protection against the clastogenicity induced by CCNU and whether the hypersensitivity of MMR-defective cells is extended to other cross-linking agents. An increase in cell killing and in the frequency of micronuclei was observed after CCNU exposure in 2 hPMS2-defective clones (clones 6 and 7) compared with the parental HeLa cells. Introduction of a wild-type copy of chromosome 7 in clone 7 led to re-expression of the hPMS2 protein and brought survival and chromosomal damage upon CCNU exposure to parental levels. Our data indicate that MMR protects against the clastogenic damage induced by this drug. The hPMS2-defective HeLa cells were also hypersensitive to killing by mitomycin C. Mitomycin C sensitivity was confirmed in an hMLH1-defective clone derived from Raji cells and in msh2-defective mouse embryo fibroblasts derived from knock-out mice. hPMS2-defective and parental HeLa cells were transplanted into nude mice, and the animals were treated with mitomycin C. While parental cell growth rate was unaffected, the growth of MMR-defective tumor was significantly reduced. Our results indicate that the in vitro hypersensitivity to mitomycin C conferred by loss of MMR is paralleled in vivo and may have implications for the chemotherapy of MMR-defective tumors.

Antibiotics for preventing respiratory tract infections in adults receiving intensive care

OBJECTIVES

Pneumonia is an important cause of mortality in intensive care units. The objective of this review was to assess the effects of antibiotics for preventing respiratory tract infections and overall mortality in adults receiving intensive care.

SEARCH STRATEGY

We searched MEDLINE, proceedings of scientific meetings and reference lists of articles from January 1984 to September 1997. We also contacted investigators in the field.

SELECTION CRITERIA

Randomised trials of antibiotic prophylaxis for respiratory tract infections and deaths among adult intensive care unit patients.

DATA COLLECTION AND ANALYSIS

Trials were assessed for quality and investigators contacted for additional information.

MAIN RESULTS

Overall 33 trials involving 5727 people were included. There was variation in the antibiotics used, patient characteristics and the risk of respiratory tract infections and mortality in the control groups. In 16 trials (involving 3493 patients) of a topical and systemic antibiotic combination, the average rates of respiratory tract infections and deaths in the control group were 33% and 28% respectively. There was a significant reduction of both respiratory tract infections (odds ratio 0.36, 95% confidence interval 0.30 to 0. 43) and total mortality (odds ratio 0.80, 95% confidence interval 0. 68 to 0.93). On average five patients needed to be treated to prevent one infection and 23 treated to prevent one death. In 17 trials (involving 2366 patients) of topical antimicrobials the rates of respiratory tract infections and deaths in the control groups were 30% and 24% respectively. There was a significant reduction of respiratory tract infections (odds ratio 0.57, 95% confidence interval 0.46 to 0.69) but not in total mortality (odds ratio 1.01, 95% confidence interval 0.84 to 1.22).

REVIEWER'S CONCLUSIONS

A combination of topical and systemic prophylactic antibiotics can reduce respiratory tract infections and overall mortality in adult patients receiving intensive care. [This abstract has been prepared centrally.]

Enhanced anti-tumor effects with microencapsulated c-myc antisense oligonucleotide

A phosphorothioate c-myc antisense oligonucleotide was complexed with zinc and encapsulated into injectable biodegradable microspheres. The efficacy of this novel formulation was compared with intravenous administration of the unencapsulated drug in human melanoma and leukemia xenografts in immunocompromised mice. The microencapsulated formulation was more effective as shown by reduced tumor growth, a decreased number of metastases, reduced c-myc expression, and increased survival in the melanoma model, and decreased metastatic potential and increased survival in the leukemia model. These results show that, as has been demonstrated previously with protein and peptide drugs, greater therapeutic efficacy can be obtained when antisense oligonucleotides are delivered from sustained-release formulations.

Increase of cisplatin sensitivity by c-myc antisense oligodeoxynucleotides in a human metastatic melanoma inherently resistant to cisplatin

In this study, we evaluated the role of the c-myc oncogene in response to cisplatin (DDP) treatment using two melanoma lines derived from the primary tumor (LP) and metastatic lymph node (LM) of the same patient. These cell lines, which retain the phenotypic profile of the original tumors, were studied for growth behavior, expression of c-Myc oncoprotein, and HLA-I antigen. The LM line shows a higher tumorigenic ability, an increased expression of c-Myc protein, and a lack of HLA-I antigen, compared with the LP line. In addition, LP tumor was relatively sensitive to DDP administration, whereas LM tumor was resistant to DDP treatment. To verify whether the increased c-Myc expression observed in the LM line might be responsible for DDP resistance, a c-myc antisense phosphorothioate oligodeoxynucleotide ([S]ODN) was used to down-regulate c-Myc expression. The administration of DDP plus c-myc antisense [S]ODNs produced a decrease in c-Myc protein levels of approximately 50%, accompanied by a tumor weight inhibition of 65%, similar to that obtained when the sensitive line was treated with DDP alone (tumor weight inhibition = 70%). Analysis of apoptosis demonstrated that the sensitivity to DDP of the LP line was related to the ability of tumor cells to undergo apoptosis. Conversely, DDP treatment was not able to induce apoptosis in the LM line, whereas apoptosis was evident both after treatment with c-myc antisense [S]ODNs alone and, more extensively, in combination with DDP. Taken together, these results clearly indicate an important role of c-myc oncogene in the resistance of melanoma to DDP and demonstrate that treatment with c-myc antisense [S]ODN sensitizes a human melanoma line to DDP treatment.

Levels of expression of hRPB11, a core subassembly subunit of human RNA polymerase II, affect doxorubicin sensitivity and cellular differentiation

We have previously shown that the human RNA polymerase II subunit 11 (hRPB11) is among the proteins specifically downregulated upon Doxorubicin (Dox) treatment of human cancer cell lines, and that Dox resistant clones derived upon drug selection express about 20% of the protein present in the original parental cell line. Given the prominent role that this subunit appears to have in eukaryotic cells, and the fact that its deletion causes lethality in yeast, we wanted to test the effect of the reintroduction of parental cell line levels of this subunit in Dox resistant colon cancer cells (LoVoDX). Stable transfectants of LoVoDX expressing parental (LoVoH) levels of hRPB11 showed a reduced sensitivity to the drug without changing the response of these cells to other chemotherapeutic agents, confirming a specific inverse correlation between cellular Dox sensitivity anti-hRPB11 levels of expression. In addition we show here that the levels of expression of this same RNA polymerase II subunit directly affect cellular differentiation, reducing the rate of cell proliferation, clonogenicity and increasing the expression of E-cadherin, a marker of epithelial cell differentiation. As expected from cells with these characteristics, upon in vivo administration of these clones in nude mice, we detected a significant reduction in the size and time of appearance of the primary tumors and overall metastatic capability. Finally, the role played by hRPB11 in regulating the transcription of specific genes is underlined by transient transfection experiments that show transactivation of the E-cadherin promoter by this protein.

Effectiveness of antibiotic prophylaxis in critically ill adult patients: systematic review of randomised controlled trials

OBJECTIVE

To determine whether antibiotic prophylaxis reduces respiratory tract infections and overall mortality in unselected critically ill adult patients.

DESIGN

Meta-analysis of randomised controlled trials from 1984 and 1996 that compared different forms of antibiotic prophylaxis used to reduce respiratory tract infections and mortality with aggregate data and, in a subset of trials, data from individual patients.

SUBJECTS

Unselected critically ill adult patients; 5727 patients for aggregate data meta-analysis, 4343 for confirmatory meta-analysis with data from individual patients.

MAIN OUTCOME MEASURES

Respiratory tract infections and total mortality.

RESULTS

Two categories of eligible trials were defined: topical plus systemic antibiotics versus no treatment and topical preparation with or without a systemic antibiotic versus a systemic agent or placebo. Estimates from aggregate data meta-analysis of 16 trials (3361 patients) that tested combined treatment indicated a strong significant reduction in infection (odds ratio 0.35; 95% confidence interval 0.29 to 0.41) and total mortality (0.80; 0.69 to 0.93). With this treatment five and 23 patients would need to be treated to prevent one infection and one death, respectively. Similar analysis of 17 trials (2366 patients) that tested only topical antibiotics indicated a clear reduction in infection (0.56; 0.46 to 0.68) without a significant effect on total mortality (1.01; 0.84 to 1.22). Analysis of data from individual patients yielded similar results. No significant differences in treatment effect by major subgroups of patients emerged from the analyses.

CONCLUSIONS

This meta-analysis of 15 years of clinical research suggests that antibiotic prophylaxis with a combination of topical and systemic drugs can reduce respiratory tract infections and overall mortality in critically ill patients. This effect is significant and worth while, and it should be considered when practice guidelines are defined.

c-myc antisense oligodeoxynucleotides enhance the efficacy of cisplatin in melanoma chemotherapy in vitro and in nude mice

This study was designed to assess the efficacy of a new antimelanoma therapeutic strategy that relies on the use of a c-myc antisense 15-mer phosphorothioate oligodeoxynucleotide ([S]ODN), in combination with cisplatin (cis-diamminedichloroplatinum; DDP), which is currently used in the clinical management of melanoma patients. Proliferation and colony formation of melanoma cells were both inhibited by the DDP/c-myc antisense [S]ODN combination to a greater extent than that observed with either agent alone. Inhibition was most effective when DDP was followed by c-myc antisense [S]ODNs. Cell cycle flow cytometric analysis of cells exposed to the two agents either alone or in combination demonstrated that (a) c-myc antisense [S]ODNs induced an accumulation of cells in S phase and apoptosis in a fraction of the cells, detectable at day 5 after the beginning of treatment; (b) DDP induced a block in G2-M phase detectable at day 1, which was partially recovered, and apoptosis similar in extent to that induced by c-myc antisense [S]ODNs; and (c) DDP and c-myc antisense [S]ODNs together induced arrest in G2-M phase, which was maximum at day 3, i.e., delayed as compared to the block induced by DDP. The combination induced a higher percentage of apoptosis, evident at day 3 from the start of treatment, that correlated with a marked reduction in Bcl-2 expression. Mice bearing human melanoma xenografts and treated sequentially with DDP and c-myc antisense [S]ODNs showed a higher inhibition of tumor growth, reduction in the number of lung metastases, and increase in life span compared with those treated with either agent alone. Together, these data lend support to the development of anticancer therapies involving oncogene-targeted antisense ODNs and conventional antineoplastic drugs.

N-methylformamide induces changes on adhesive properties and lung-colonizing potential of M14 melanoma cells

We have studied whether N-methylformamide can affect the expression pattern of adhesion molecules and the attachment behaviour of M14 human melanoma cells. The role of N-methylformamide on experimental and spontaneous pulmonary metastases from M14 cells in nude mice was also investigated. We demonstrate that N-methylformamide in vitro pretreatment of M14 cells, although inducing a significant increase in the expression of alpha2beta1, alpha6beta1 and alpha(v)beta3 integrin receptors, slightly modifies alpha5beta1 heterodimer and beta1 subunit expression. After this modulation, enhancement of cell adhesion to laminin, collagen I, vitronectin and fibrinogen, which is blocked by specific anti-integrin antibodies, also occurs. No changes in binding to fibronectin are observed. In vitro N-methylformamide pretreatment also results in an increased number of experimental nodules and in a decrease in spontaneous metastases. Moreover, in vivo treatment with N-methylformamide significantly reduces the number of spontaneous metastases. Collectively, these data show that N-methylformamide modulates the expression of some adhesion receptors, cell adhesion to laminin, collagen I, vitronectin and fibrinogen as well as the metastatic behaviour of M14 cells. Our data also suggest that the effect of N-methylformamide might be evaluated in combination with antineoplastic agents for the treatment of human melanoma.

[An index of daily intensive care unit activity]

OBJECTIVE

To set up an index for the evaluation of type of interventions and procedures applied a prerequisite for the evaluation of appropriateness of ICU's activity.

DESIGN

Observation prospective study.

PATIENTS

2507 patients out of the 5030 enrolled in the cohort study.

MEASUREMENTS

A cross-sectional assessment of the volume and intensity of treatment--level of care--delivered to patients was performed at a preidentified index day. A check list of procedures was utilized. Intensive high level treatment was demonstrated by the application of procedures suggesting one or more organs or vital functions intensively supported. Sub-intensive treatment was defined by the application of procedures indicating monitoring or treatments not exclusively performed in intensive environment.

RESULTS

3955 samples were collected over 9 index days; 2707 (68.3%) resulted in intensive, 1227 (30.7%) subintensive or intermediate and 41 (1%) ward treatments. Out of the intensive samples, 63.4% received only one intensive procedure, while 27.9% two. Ventilatory support was the most frequently (90.4%) utilized intensive procedure. Overall 99% of the samples were characterized by treatments/procedures too invasive for normal ward.

CONCLUSIONS

The proposed method gives the opportunity to easily evaluate the level of care and then the appropriateness of ICU care.

Bcl-2 overexpression enhances the metastatic potential of a human breast cancer line

Bcl-2 protein has been shown to contribute to oncogenesis because it can transform and immortalize cells in cooperation with c-myc, ras, or viral genes. However, in vivo studies have not yet established whether bcl-2 can play a role in metastasis. Here we investigate the potential metastatic role of bcl-2. We introduced the human bcl-2 gene into a low bcl-2 expressing human breast cancer cell line MCF7 ADR. We demonstrate that two bcl-2 overexpressing clones injected intravenously or intramuscularly into nude mice induce a significantly higher number of experimental and spontaneous lung metastases compared to the control transfectant clone. We demonstrate that bcl-2 overexpressing clones are more invasive and migratory in response to chemotactic stimuli than the control transfectant clone. Furthermore, zymographic analysis shows that secretion of 72 and 92 kDa gelatinases increases in the two bcl-2 overexpressing transfectants. Tumors originating from bcl-2 overexpressing clones also show a decrease in the latency period of tumor appearance. In conclusion, our data show that bcl-2 overexpression enhances both tumorigenicity and metastatic potential of MCF7 ADR cells by inducing metastasis-associated properties.

Functional role of alpha4beta1 and alpha5beta1 integrin fibronectin receptors expressed on adriamycin-resistant MCF-7 human mammary carcinoma cells

Cytofluorimetric and reverse-transcription polymerase chain reaction (RT-PCR) analysis showed that adriamycin-resistant (ADRR), but not sensitive (WT), MCF-7 human mammary carcinoma cell lines express alpha4beta1 and alpha5beta1 integrins. ADR(R) cells adhere to fibronectin (FN), and only alpha5beta1 is involved in cell adhesion to this glycoprotein, while alpha4beta1 mediates cell binding to the cellular counter-receptor VCAM-1. Proliferation assays showed that FN, but not VCAM-1, delivers a mitogenic signal to quiescent ADR(R) MCF-7 cells. The activating signal is mediated by alpha5beta1, since cell proliferation is inhibited in the presence of RGD peptide or specific antibody. Cell cycle analysis demonstrated that cell/FN interaction induces the re-entry of ADR(R) MCF-7 into S phase, and prevents them from undergoing serum deprivation-induced apoptosis. Our data suggest that the presence of alpha5beta1 on the resistant cells enables them to draw advantage from FN for both cell growth and survival.

Effect of cisplatin and c-myb antisense phosphorothioate oligodeoxynucleotides combination on a human colon carcinoma cell line in vitro and in vivo

We investigated the effect of c-myb antisense phosphorothioate oligodeoxynucleotides [(S)ODNs] and cisplatin (CDDP) combination on the human colon carcinoma cell line LoVo Dx both in vitro and in nude mice bearing LoVo Dx solid tumour. We show that antisense (S)ODN treatment decreases c-myb mRNA and protein expression, induces growth arrest in the G1 phase of the cell cycle, and inhibits cell proliferation. In vivo treatment with c-myb antisense (S)ODNs results in a reduction in tumour growth. A greater inhibition of cell proliferation in vitro and a higher increase of tumour growth inhibition and growth delay in vivo were obtained with the combination of (S)ODNs and CDDP than when the two agents were administered separately. This comparative study, using the same tumour cell line in vitro and in vivo, suggests that c-myb antisense (S)ODNs might be useful in the therapy of colon cancer in combination with antineoplastic drugs.

Antitumor effect of c-myc antisense phosphorothioate oligodeoxynucleotides on human melanoma cells in vitro and and in mice

BACKGROUND

Phosphorothioate oligodeoxynucleotides ([S]ODNs) contain a modified internucleoside phosphate backbone. Antisense [S]ODNs targeted to specific oncogenes have been used with some therapeutic success in animal models human leukemia; however, the potential for antisense [S]ODN treatment of solid tumors has only recently been explored.

PURPOSE

We evaluated the effects of antisense [S]ODNs targeted to the c-myc oncogene on the proliferation of human melanoma cells in vitro and on the growth of human melanoma xenografts in CD-1 nude (nu/nu) mice,

METHODS

The effects of 15-mer [S]ODNs containing c-myc sense, c-myc antisense, and two different scrambled sequences on the proliferation and viability of cultures of three established human melanoma cell lines (M14, JR8, and PLF2) were determined by measuring cell numbers and use of the trypan blue exclusion test. The induction of apoptosis in these cells following treatment with [S]ODNs was evaluated by fluorescence-activated cell sorter (FACS) analysis. FACS analysis was also used to determine the effects of [S]ODN treatment on the proliferation of primary cultures of a human melanoma explant (NG cells). The expression of c-Myc protein in cultured NG cells after treatment with [S]ODNs was examined by western blot analysis. The antitumor activity and the toxic effects of several [S]ODN treatment regimens were monitored by measuring differences in tumor weight (percent tumor weight inhibition), tumor growth rate (tumor growth inhibition), animal lifespan (percent increase in lifespan), the number of toxic deaths and the median number of long metastases in treated and control mice bearing NG xenografts. c-Myc protein expression in NG tumor cells following [S]ODN treatment was evaluated by FACS analysis, and the extent of apoptosis in these cells was determined by FACS analysis and morphologic examination.

RESULTS

Treatment with antisense [S]ODNs, but not the others, inhibited the growth of all tested melanoma cultures in vitro; FACS analysis revealed that growth inhibition was associated with the induction of apoptosis. Antisense [S]ODN treatment also led to reduced celluLar levels of c-Myc protein. In vivo, [S]ODN antitumor activity and toxicity were dose and schedule dependent; however, only antisense [S]ODNs exhibited antitumor activity. Mice bearing NG xenografts treated with antisense [S]ODNs showed a marked inhibition of tumor growth, a reduction in the number of long metastases, and an increase in life span. Reduced levels of c-Myc protein and increased levels of apoptosis were also observed in NG tumor cells following antisense [S]ODN treatment.

CONCLUSIONS

treatment of human melanoma cells and solid tumors with antisense [S]ODNs targeted to c-Myc inhibits their growth and is associated with the induction of apoptosis.

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.

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.

Ruboxyl, a new nitroxyl derivative of daunorubicin - acute toxicity and antitumor effect in animals

Ruboxyl (RBX), a new nitroxyl derivative anthracycline, showed an interesting cytotoxic effect on in vitro established human cell lines and an antitumor activity in tumor-bearing animals. In this study, we further investigated the antitumor effect of this drug compared to Doxorubicin (DX) in four in vivo systems of experimental murine tumors. Our data demonstrate that RBX had little effect on the growth of primary tumor, and on the survival, in mice bearing Lewis lung carcinoma (3LL), while the drug showed a higher effect on the growth of B 16 melanoma. In both the experimental murine systems the activity of RBX was similar to that exerted by DX. As regards the leukemia models, RBX induced a significant increase on survival in mice bearing both L1210 or L5178Y leukemias. However, the effect on survival and the number of long-term survivors (LTS) were lower than that observed following DX treatment.

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.