ABSTRACT
Stormwater runoff from urban and suburban areas can carry hazardous pollutants directly into aquatic ecosystems. These pollutants, such as metals, nutrients, aromatic hydrocarbons, pesticides, and pharmaceuticals, are very toxic to aquatic organisms. Recently, significant amounts of zinc oxide engineered nanoparticles (ZnO-NPs) have been detected in urban stormwater and its bioretention systems. This raises concerns about a potential increase of stormwater toxicity and reduced performance of the treatment infrastructures. To tackle these issues, we developed a simple, low-cost bioretention system to remediate stormwater and retain ZnO-NPs. This system retained up to 73% Zn, 66% Cu, and >99% Pb. However, the removal efficiency for Pb was lower after adding ZnO-NPs to the system, possibly due to the remobilization of Pb phosphates. The effect of ZnO-NPs on stormwater toxicity and metal accumulation in wetland plants was also evaluated.
Subject(s)
Metals, Heavy , Nanoparticles , Water Pollutants, Chemical , Zinc Oxide , Ecosystem , Lead , Rain , Solubility , Water Pollutants, Chemical/analysis , Water Pollutants, Chemical/toxicity , Zinc , Zinc Oxide/toxicityABSTRACT
Deregulation of p16INK4A is a critical event in melanoma susceptibility and progression. It is generally assumed that the major effect of loss of p16 function is mediated through the CDK-cyclin pathway via its influence on the pocket protein (PP) pRb. However, there are also two other PPs, p107 and p130, which, when phosphorylated by CDK-cyclin complexes, play a role in permitting cell progression. Cohorts of mice carrying melanocyte-specific knockouts (KOs) of various combinations of the three PPs were generated. Mice null for pRb, p107, p130 or any combination of double mutants did not develop melanoma. Surprisingly, melanocyte-specific loss of all three PPs facilitated melanoma development (median age of onset 308 days, penetrance 40% at 1 year). Tumorigenesis was exacerbated by Trp53 co-deletion (median age of onset 275 days, penetrance 82% at 1 year), with cell culture studies indicating that this difference may result from the apoptotic role of Trp53. Melanomas in PP;Trp53-deficient mice lacked either Ras or Braf mutations, and hence developed in the absence of constitutive MAPK pathway activation. The lag period between induction of total PP or PP/Trp53 KO and melanoma development indicates that additional genetic or epigenetic alterations may account for neoplastic progression. However, exome sequencing of PP;Trp53 KO melanomas failed to reveal any additional recurrent driver mutations. Analysis of the putative mutation signature of the PP;Trp53 KO melanomas suggests that melanocytes are primed for transformation via a mutagenic mechanism involving an excess of T>G substitutions, but not involving a preponderance of C>T substitutions at CpG sites, which is the case for most spontaneous cancers not driven by a specific carcinogen. In sum, deregulation of all three PPs appears central to neoplastic progression for melanoma, and the customary reference to the p16INKA/CDK4/pRB pathway may no longer be accurate; all PPs are potentially critical targets of CDK-cyclins in melanoma.
Subject(s)
Cell Transformation, Neoplastic/metabolism , Cell Transformation, Neoplastic/pathology , MAP Kinase Signaling System , Melanocytes/metabolism , Melanocytes/pathology , Animals , Humans , Melanocytes/enzymology , Mice , Mice, Knockout , Tumor Suppressor Protein p53/metabolismABSTRACT
Basal-like breast cancers are highly aggressive malignancies associated with very poor prognosis. Although these cancers may initially respond to first-line treatment, they become highly resistant to standard chemotherapy in the metastatic setting. Chemotherapy resistance in basal-like breast cancers is associated with highly selective overexpression of the homeobox transcription factor Engrailed 1 (EN1). Herein, we propose a novel therapeutic strategy using poly(glycidyl methacrylate) nanoparticles decorated with poly(acrylic acid) that enable dual delivery of docetaxel and interference peptides designed to block or inhibit EN1 (EN1-iPep). We demonstrate that EN1-iPep is highly selective in inducing apoptotic cell death in basal-like cancer cells with negligible effects in a non-neoplastic human mammary epithelial cell line. Furthermore, we show that treatment with EN1-iPep results in a highly synergistic pharmacological interaction with docetaxel in inhibiting cancer cell growth. The incorporation of these two agents in a single nanoformulation results in greater anticancer efficacy than current nanoparticle-based treatments used in the clinical setting.
Subject(s)
Antineoplastic Agents/administration & dosage , Drug Delivery Systems , Homeodomain Proteins/chemistry , Nanoparticles , Apoptosis , Breast Neoplasms , Cell Line, Tumor , Docetaxel , Humans , Peptides , Taxoids/administration & dosageABSTRACT
The expression of voltage-gated calcium channels (VGCCs) has not been reported previously in melanoma cells in spite of increasing evidence of a role of VGCCs in tumorigenesis and tumour progression. To address this issue we have performed an extensive RT-PCR analysis of VGCC expression in human melanocytes and a range of melanoma cell lines and biopsies. In addition, we have tested the functional expression of these channels using Ca(2+) imaging techniques and examined their relevance for the viability and proliferation of the melanoma cells. Our results show that control melanocytes and melanoma cells express channel isoforms belonging to the Ca(v) 1 and Ca(v) 2 gene families. Importantly, the expression of low voltage-activated Ca(v) 3 (T-type) channels is restricted to melanoma. We have confirmed the function of T-type channels as mediators of constitutive Ca(2+) influx in melanoma cells. Finally, pharmacological and gene silencing approaches demonstrate a role for T-type channels in melanoma viability and proliferation. These results encourage the analysis of T-type VGCCs as targets for therapeutic intervention in melanoma tumorigenesis and/or tumour progression.
Subject(s)
Calcium Channels/genetics , Melanoma/genetics , Skin Neoplasms/genetics , 3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethyl-5-nitro-4-(2-(trifluoromethyl)phenyl)-, Methyl ester/metabolism , Calcium/metabolism , Calcium Channel Blockers/pharmacology , Calcium Channels/metabolism , Cell Cycle/drug effects , Cell Cycle/genetics , Cell Hypoxia/drug effects , Cell Hypoxia/genetics , Cell Line, Tumor , Cell Lineage/drug effects , Cell Proliferation/drug effects , Cell Survival/drug effects , Cell Survival/genetics , Flow Cytometry , Fura-2/metabolism , Gene Expression Regulation, Neoplastic/drug effects , Humans , Manganese/metabolism , Melanocytes/drug effects , Melanocytes/metabolism , Melanocytes/pathology , Melanoma/pathology , Mibefradil/pharmacology , Molecular Imaging , Protein Isoforms/genetics , Protein Isoforms/metabolism , Reverse Transcriptase Polymerase Chain Reaction , Skin Neoplasms/metabolism , Skin Neoplasms/pathology , Up-Regulation/drug effects , Up-Regulation/geneticsABSTRACT
Research into molecular targets for drug development in melanoma is starting to bear fruit. Of the drugs tested to date in patients with metastatic melanoma, those that have yielded the best results are V600E BRAF inhibitors in melanomas carrying the V600E mutation; c-kit tyrosine kinase activity inhibitors in melanomas carrying c-kit mutations; and anti-cytotoxic T lymphocyte antigen 4 (CTLA-4) antibodies, which block the mechanisms involved in immune tolerance. Many problems have yet to be resolved in these areas, however, such as the rapid development of resistance to BRAF and c-kit inhibitors and the lack of biomarkers to predict treatment response in the case of CTLA-4 blockers. We review the results of targeted therapy with these and other drugs in metastatic melanoma and discuss what the future holds for this field.
Subject(s)
Antineoplastic Agents/therapeutic use , Melanoma/drug therapy , Molecular Targeted Therapy , Abatacept , Angiogenesis Inhibitors/pharmacology , Angiogenesis Inhibitors/therapeutic use , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Biomarkers, Tumor , Cell Adhesion Molecules/antagonists & inhibitors , Clinical Trials as Topic , Drug Design , Histone Deacetylase Inhibitors/pharmacology , Histone Deacetylase Inhibitors/therapeutic use , Humans , Immunoconjugates/therapeutic use , Immunotherapy , Melanoma/chemistry , Melanoma/genetics , Neoplasm Proteins/antagonists & inhibitors , Neoplasm Proteins/genetics , Oligonucleotides, Antisense/pharmacology , Oligonucleotides, Antisense/therapeutic use , Protease Inhibitors/pharmacology , Protease Inhibitors/therapeutic use , Protein Kinase Inhibitors/pharmacology , Protein Kinase Inhibitors/therapeutic use , Signal Transduction/drug effects , Tumor Escape/drug effectsABSTRACT
Sorafenib induces apoptosis and enhances Tumour Necrosis Factor-Related Apoptosis-Inducing Ligand (TRAIL)-induced cell killing of tumoural cells. We have investigated the effects of the multikinase inhibitor Sorafenib alone or in combination with TRAIL and agonistic Fas antibodies on endometrial carcinoma cells. We have also focused on the search of the differential molecular mechanisms by which Sorafenib induces cell death and the ones involved in sensitisation to TRAIL. In the present study, we show that Sorafenib induces apoptosis of both endometrial cancer cell lines and human primary cultures and sensitises these cells to TRAIL and agonistic Fas antibodies (aFas)-induced apoptosis. However, Raf/MEK/ERK inhibition by Sorafenib was not responsible for Sorafenib cell death or TRAIL sensitisation of endometrial cancer cells. Sorafenib treatment correlated with a downregulation of both FLICE-Inhibitory Protein (FLIP) and myeloid cell leukaemia-1 (Mcl-1), caused by a proteasomal degradation of both proteins. We evaluated the contribution of FLIP and Mcl-1 downregulation in apoptosis triggered by Sorafenib alone or Sorafenib plus TRAIL. Interestingly, cell death caused by Sorafenib was mediated by downregulation of Mcl-1, but not by FLIP. In contrast, we found that Sorafenib sensitisation of endometrial carcinoma cells to TRAIL- and Fas-induced apoptosis was dependent on FLIP but not on Mcl-1 downregulation. Altogether, we discern the dual mechanisms by which Sorafenib causes cell death from those involved in death receptor sensitisation.
Subject(s)
Adenocarcinoma/pathology , Antineoplastic Agents/pharmacology , Apoptosis/drug effects , Benzenesulfonates/pharmacology , Endometrial Neoplasms/pathology , Pyridines/pharmacology , TNF-Related Apoptosis-Inducing Ligand/pharmacology , Adenocarcinoma/metabolism , Antineoplastic Combined Chemotherapy Protocols/pharmacology , CASP8 and FADD-Like Apoptosis Regulating Protein/metabolism , Dose-Response Relationship, Drug , Drug Screening Assays, Antitumor/methods , Endometrial Neoplasms/metabolism , Female , Humans , MAP Kinase Signaling System/drug effects , Myeloid Cell Leukemia Sequence 1 Protein , Neoplasm Proteins/metabolism , Niacinamide/analogs & derivatives , Phenylurea Compounds , Protein Kinase Inhibitors/pharmacology , Proto-Oncogene Proteins c-bcl-2/metabolism , Sorafenib , Tumor Cells, Cultured , fas Receptor/immunologyABSTRACT
Somatostatin analogues (SAs) are potential anticancer agents. This study was designed to investigate the expression of somatostatin receptors (SSTRs) in melanoma cells and the effect of two SAs on cell proliferation and viability. Eighteen primary and metastatic human cutaneous melanoma cell lines were treated with octreotide and SOM230. Expression of SSTR1, SSTR2, SSTR3 and SSTR5 was assessed by real-time polymerase chain reaction. Proliferation, viability and cell death were assessed using standard assays. Inhibition was modelled by mixed-effect regression. Melanoma cells expressed one or more SSTR. Both SAs inhibited proliferation of most melanoma cell lines, but inhibition was < 50%. Neither SA affected cell viability or induced cell death. The results suggest that melanoma cell lines express SSTRs. The SAs investigated, under the conditions used in this study, did not, however, significantly inhibit melanoma growth or induce cell death. Novel SAs, combination therapy with SAs and their anti-angiogenic properties should be further investigated.
Subject(s)
Gene Expression Regulation, Neoplastic/drug effects , Melanoma/genetics , Melanoma/pathology , Octreotide/pharmacology , Receptors, Somatostatin/genetics , Somatostatin/analogs & derivatives , Cell Line, Tumor , Cell Proliferation/drug effects , Humans , Receptors, Somatostatin/metabolism , Somatostatin/pharmacologyABSTRACT
BACKGROUND: Cutaneous malignant melanoma is an aggressive type of skin cancer which causes disproportionate mortality in young and middle-aged adults. Once disseminated, melanoma can be considered an incurable disease, highly resistant to standard antineoplastic treatment, such as chemotherapy or radiation therapy. The proteasome represents a novel target for cancer therapy that can potentially be used in melanoma. OBJECTIVES: To assess the effect of four structurally different proteasome inhibitors on human cutaneous melanoma-derived cell lines. METHODS: Sixteen human cutaneous melanoma-derived cell lines which are original were obtained from patients who were treated by two of the authors. Cells were cultured, exposed to proteasome inhibitors (bortezomib, ALLN, MG-132 and epoxomicin) and then assayed for cell cycle and cell death analyses. RESULTS: Proteasome inhibitors inhibited the in vitro growth of melanoma cells, and this effect was due to a reduction in cell proliferation rate and an induction of both caspase-dependent and caspase-independent cell death. Moreover, release of apoptosis-inducing factor was observed in the presence of the broad-specificity caspase inhibitor BAF (Boc-D-fmk). In addition, the four different proteasome inhibitors induced caspase 2 processing. CONCLUSIONS: This study provides information regarding the in vitro effects of proteasome inhibitors on melanoma cell lines, and the molecular mechanisms involved. It also gives support to the future use of such inhibitors in the treatment of patients with melanoma, either administered alone or in combination with other drugs.
Subject(s)
Apoptosis/drug effects , Boronic Acids/pharmacology , Cell Death/drug effects , Melanoma/drug therapy , Protease Inhibitors/pharmacology , Pyrazines/pharmacology , Skin Neoplasms/drug therapy , Boronic Acids/administration & dosage , Bortezomib , Cell Line, Tumor , Cell Proliferation/drug effects , Drug Resistance, Multiple , Female , Humans , Male , Melanoma/etiology , Protease Inhibitors/administration & dosage , Pyrazines/administration & dosage , Skin Neoplasms/etiology , Treatment OutcomeABSTRACT
Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) has emerged as a promising antineoplastic agent because of its ability to selectively kill tumoral cells. However, some cancer cells are resistant to TRAIL-induced apoptosis. We have previously demonstrated that in endometrial carcinoma cells such resistance is caused by elevated FLICE-inhibitory protein (FLIP) levels. The present study focuses on the mechanisms by which FLIP could be modulated to sensitize endometrial carcinoma cells to TRAIL-induced apoptosis. We find that inhibition of casein kinase (CK2) sensitizes endometrial carcinoma cells to TRAIL- and Fas-induced apoptosis. CK2 inhibition correlates with a reduction of FLIP protein, suggesting that CK2 regulates resistance to TRAIL and Fas by controlling FLIP levels. FLIP downregulation correlates with a reduction of mRNA and is prevented by addition of the MG-132, suggesting that CK2 inhibition results in a proteasome-mediated degradation of FLIP. Consistently, forced expression of FLIP restores resistance to TRAIL and Fas. Moreover, knockdown of either FADD or caspase-8 abrogates apoptosis triggered by inhibition of CK2, indicating that CK2 sensitization requires formation of functional DISC. Finally, because of the possible role of both TRAIL and CK2 in cancer therapy, we demonstrate that CK2 inhibition sensitizes primary endometrial carcinoma explants to TRAIL apoptosis. In conclusion, we demonstrate that CK2 regulates endometrial carcinoma cell sensitivity to TRAIL and Fas by regulating FLIP levels.
Subject(s)
Antineoplastic Agents/pharmacology , CASP8 and FADD-Like Apoptosis Regulating Protein/biosynthesis , Casein Kinase II/metabolism , Drug Resistance, Neoplasm/drug effects , Endometrial Neoplasms/metabolism , Neoplasm Proteins/metabolism , TNF-Related Apoptosis-Inducing Ligand/pharmacology , fas Receptor/pharmacology , Antineoplastic Agents/therapeutic use , Apoptosis/drug effects , Apoptosis/genetics , CASP8 and FADD-Like Apoptosis Regulating Protein/genetics , Casein Kinase II/antagonists & inhibitors , Cell Line , Drug Resistance, Neoplasm/genetics , Endometrial Neoplasms/drug therapy , Endometrial Neoplasms/genetics , Endometrial Neoplasms/pathology , Female , Gene Expression Regulation, Neoplastic/drug effects , Gene Expression Regulation, Neoplastic/genetics , Humans , Leupeptins/pharmacology , Neoplasm Proteins/antagonists & inhibitors , Neoplasm Proteins/genetics , Proteasome Endopeptidase Complex/genetics , Proteasome Endopeptidase Complex/metabolism , TNF-Related Apoptosis-Inducing Ligand/therapeutic use , Tumor Cells, Cultured , fas Receptor/therapeutic useABSTRACT
Methyl inosine monophosphate (MIMP) augments preferentially the in vitro responses of human and murine lymphocytes to a T-cell mitogen such as phytohemagglutinin (PHA) and inconsistently to a B-cell mitogen such as pokeweed or lipopolysaccharide (LPS). In a normal interleukin-2-dependent cell line (CTLL), MIMP showed little or no effect on IL-2 action; however, in a murine CTLL line exhibiting impaired responses to IL-2, MIMP stimulated thymidine incorporation and restored the response to IL-2. MIMP augments the PHA responses of both CD4+ and CD8+ human peripheral blood T-cells. The effect of MIMP to augment the PHA response of human lymphocytes is paralleled by the parent molecule, IMP. MIMP, but not IMP, is resistant to hydrolysis by 5'nucleotidase; thus, MIMP appears to be a protected analogue of IMP which is capable of in vivo action. MIMP (100 micrograms/ml) augments the PHA responses of 15 to 24 elderly humans. MIMP also augments the PHA responses of eight HIV-infected pre-AIDS patients but not of eight AIDS patients. When PHA responses of human lymphocytes are suppressed in vitro by an HIV-derived immunosuppressive peptide, interferon alpha, or prostaglandin PGE2, MIMP (0.1-100 micrograms/ml) progressively restores the depressed response; however, when the suppression is severe (greater than 50%), MIMP cannot restore the response. These data indicate that MIMP potentiates normal T-lymphocyte mitogen responses and restores those impaired by a variety of inflammatory and immunosuppressive influences.
Subject(s)
Antiviral Agents/pharmacology , Immunosuppressive Agents/antagonists & inhibitors , Inosine Monophosphate/analogs & derivatives , Mitogens/physiology , T-Lymphocytes/drug effects , Animals , Cells, Cultured , Dinoprostone/physiology , Dose-Response Relationship, Drug , HIV Infections/drug therapy , Humans , Inosine Monophosphate/pharmacology , Interferon-alpha/drug effects , Mice , Spleen/cytology , Spleen/drug effectsSubject(s)
Antiviral Agents/pharmacology , Immunity/drug effects , Inosine Monophosphate/analogs & derivatives , Animals , Antibody Formation/drug effects , Humans , Immunity, Cellular/drug effects , Inosine Monophosphate/chemistry , Inosine Monophosphate/pharmacology , Lymphocyte Activation/drug effects , T-Lymphocytes/drug effects , T-Lymphocytes/immunologyABSTRACT
Inclusion of 10% ethanol with 6.8 ppm N-nitrosodiethylamine in the drinking water of strain A male mice resulted in a 4-fold enhancement of multiplicity of lung tumors and a 16-fold increase in incidence of fore-stomach tumors, compared with carcinogen alone. Given with 40 ppm N-nitrosopyrrolidine, ethanol caused a 5.5-fold increase in lung tumor multiplicity. The inclusion of 15% ethanol with N6-(methylnitroso)adenosine, given orally to Swiss female mice, led to reduced body weights and shortened survival time related to hemangiosarcoma occurrence or increased incidence of thymic lymphoma, depending on dose of carcinogen. The data provide additional support for the proposal that co-administered ethanol increases the tumorigenicity of nitrosamines by blocking hepatic first-pass clearance.
Subject(s)
Carcinogens/pharmacology , Ethanol/toxicity , Animals , Diethylnitrosamine/pharmacology , Drug Interactions , Female , Lung Neoplasms/chemically induced , Male , Mice , Mice, Inbred A , N-Nitrosopyrrolidine/pharmacology , Nitrosamines/pharmacologyABSTRACT
Inosine 5'-methyl monophosphate (MIMP) is a new immunomodulator designed to improve upon the activity of other thymomimetic purines. In Balb/c mice, MIMP was assessed for toxicity and activity on immune responses. The lethal dose for half the mice (LD50) exceeded 500 mg/kg of body weight by both the parenteral and oral routes. At doses of 1-100 mg/kg, the mice showed no visible untoward effects. The antibody response of splenocytes to sheep erythrocytes (SRBC) was measured by IgM plaque-forming cells (PFC) in soft agar under optimal conditions of immunization and challenge. MIMP (1-100 mg/kg) was given by both the intraperitoneal and oral routes (gavage) at the time of SRBC injection and 4 days thereafter. The PFC response was found to be significantly augmented. The maximum effect (approximately 2x) was observed at 50 and 100 mg/kg, via intraperitoneal (i.p.) and oral routes, respectively. Increases (maximally 1.5x) in the responses of splenic lymphocytes to mitogen stimulation with phytohemagglutinin (PHA) and concanavalin A (Con A) were observed under similar conditions of MIMP treatment. SRBC-induced delayed-hypersensitivity (DTH) was also measured under optimal conditions. By both i.p. and oral routes, enhancement of DTH response was produced by the lower doses of MIMP (0.01-1 mg/kg). Again, a second peak of optimum stimulation of DTH response was produced by 50 mg/kg of MIMP when administered by both routes. The effect was observed mainly on the sensitization rather than on the expression phase. MIMP qualifies as an effective immunopotentiator in normal mice.
Subject(s)
Adjuvants, Immunologic/pharmacology , Inosine Monophosphate/analogs & derivatives , Adjuvants, Immunologic/toxicity , Animals , Antibody Formation/drug effects , Antibody-Producing Cells/drug effects , Antibody-Producing Cells/immunology , Female , Hypersensitivity, Delayed , Inosine Monophosphate/pharmacology , Inosine Monophosphate/toxicity , Lethal Dose 50 , Lymphocyte Activation/drug effects , Mice , Mice, Inbred BALB C , T-Lymphocytes/drug effects , T-Lymphocytes/immunologyABSTRACT
MIMP is a new thymomimetic purine under development for immunorestorative therapy. Lymphocytes were obtained from eight patients with acquired immunodeficiency disease (AIDS), eight with symptomatic pre-AIDS (ARC), and 22 normal controls and were stimulated in vitro with phytohemagglutinin (PHA). AIDS patients (mean CD4 counts of 40) showed PHA responses less than 10% of control while ARC patients (mean CD4 counts of 544) showed responses approximately 50% of the control responses. MIMP (0.1, 1, 10 and 100 micrograms/ml) progressively augmented the PHA responses in all these groups. The augmentation of the responses of the leukocytes of AIDS patients while statistically significant was minimal. The augmentation of the responses of ARC patients was significant and their maximal responses approached control levels. The effect of 1 micrograms/ml MIMP was comparable with that observed with indomethacin (10(-6) M) and interleukin-2 (IL2 - 4 units/ml) and was additive with each of these stimulants. In a parallel manner, MIMP restored the suppression of control lymphocytes induced by the immunosuppressive 17 amino acid fragment of the P41 peptide of HIV. In vivo experiments showed that MIMP significantly delayed death in a murine FLV AIDS model at a dose of 1 mg/kg by the oral or parenteral route. MIMP is under preclinical development for early HIV disease to forestall progression to AIDS by attenuating virus-induced immunosuppression.
Subject(s)
Adjuvants, Immunologic/therapeutic use , HIV Infections/drug therapy , Inosine Monophosphate/analogs & derivatives , Adjuvants, Immunologic/pharmacology , Adult , Animals , Female , Friend murine leukemia virus , Humans , In Vitro Techniques , Indomethacin/pharmacology , Inosine Monophosphate/pharmacology , Inosine Monophosphate/therapeutic use , Interleukin-2/pharmacology , Leukemia, Experimental/drug therapy , Lymphocytes/drug effects , Mice , Mice, Inbred BALB C , Middle Aged , PhytohemagglutininsABSTRACT
Prior work has documented the thymomimetic and immunotherapeutic activity of purine molecules related in structure to inosine. Synthesis of a series of new structures has yielded a stable methylated form of IMP resistant to hydrolysis by 5' nucleotidase. With both human peripheral blood lymphocytes and murines splenocytes, Methyl Inosine Monophosphate (MIMP) augments proliferative responses to T-cell mitogens like phytohemagglutinin (PHA), but less so, or not at all, to B-cell mitogens like pokeweed or endotoxin (LPS). MIMP does not directly stimulate lymphocytes alone in the absence of mitogen. The optimal effects of MIMP parallel the optimal effects of PHA. The magnitude of the effect is greater and more consistent than with other purine immunomodulators. MIMP is non-toxic in vitro and in vivo and is orally active in mice. Significant effects are observed as low as 0.1 and 1 micrograms/ml in vitro and 0.1 or 1 mg/kg in vivo. MIMP is a candidate third generation purine under development for immunotherapeutic purposes.
Subject(s)
Adjuvants, Immunologic/pharmacology , HIV Infections/drug therapy , Inosine Monophosphate/analogs & derivatives , Adjuvants, Immunologic/therapeutic use , Animals , HIV Infections/immunology , Humans , Inosine Monophosphate/pharmacology , Inosine Monophosphate/therapeutic use , Lymphocyte Activation/drug effects , Mice , Mice, Inbred BALB C , T-Lymphocytes/drug effects , T-Lymphocytes/immunologyABSTRACT
N-Nitrosocimetidine (NCM) is a derivative of the drug cimetidine, a methylguanidine derivative used in the treatment of peptic ulcer, and is known to be inactive as a complete mouse skin carcinogen, even when given in repeated high doses for a long period. In the current experiment, NCM was tested for its ability to initiate skin tumors on Sencar mice. It was applied at doses of 1 or 0.3 mg, 5 times/week for 6 weeks, followed by the tumor promoter 12-O-tetradecanoylphorbol-13-acetate (TPA), 1 microgram, 2 times/week for 50 weeks. Controls received acetone. The higher NCM dose had significant effects on TPA-promotable tumors, resulting in shortened time to first tumor, increased incidence of all tumors (2-fold) and of malignant tumors (4-fold), and greater tumor growth rate (2-fold), compared with the acetone/TPA-treated mice. The mice given the lower NCM dose did not exhibit increased tumor incidence, but their tumors had a significantly higher growth rate (3-fold) than those of the TPA controls. NCM without TPA treatment caused no tumors. Thus, NCM is a definitive, though weak initiator of TPA-promotable tumors. Nine tumors from the NCM-treatment groups were analyzed for activated oncogenes by the NIH 3T3 cell transfection assay. Five were positive and four of these were found by selective oligonucleotide hybridization analysis to have an A to T transversion in the second position of codon 61 of the H-ras oncogene. One of two tumors from the acetone/TPA group also contained transforming DNA and demonstrated this mutation. None of the tumors had a G----A transition mutation at the second position of codon 12 of this oncogene. Tumor initiation by NCM may then be associated with the same oncogene mutation reported for mouse skin tumors initiated by other types of carcinogens, although occurrence of the mutated oncogene in TPA controls precludes a definitive conclusion.
Subject(s)
Cimetidine/analogs & derivatives , Genes, ras , Skin Neoplasms/chemically induced , Animals , Carcinogens , Cocarcinogenesis , Dose-Response Relationship, Drug , Gene Expression Regulation, Neoplastic , Mice , Mutation , Skin Neoplasms/genetics , Skin Neoplasms/pathology , Survival Analysis , Tetradecanoylphorbol AcetateABSTRACT
N-Nitrosocimetidine (NCM) is a nitrosation product of cimetidine, a commonly-prescribed pharmaceutical agent. In spite of its known genotoxicity, NCM has failed to cause tumors in assays with rats and mice, but has given indications of enhancing or suppressive effects on tumor development. This possibility was tested by administering NCM topically to the skin or in the drinking water to mice in which tumors had been initiated by treatment with chemical carcinogens. Sencar mouse skin papillomas initiated by 7,12-dimethylbenzanthracene (DMBA) and promoted by 12-O-decanoylphorbol-13-acetate (TPA), progressed more rapidly to carcinoma on mice given treatment during stage 3 (after TPA) with NCM (1 mg/week) or N-methyl-N'-nitro-N-nitrosoguanidine (MNNG, 120 micrograms/week) [corrected] than on stage 3 acetone controls. Oral NCM (1 g/l drinking water) did not have this effect but rather suppressed development of keratoacanthomas, as did stage 3 MNNG or TPA. Primary lung tumors initiated in BALB/c mice by i.p. injection of urethane; and tumors of forestomach, lung, mammary, lymphoid and skin tissues caused in (C57BL/6 X DBA/2)F1 mice by oral DMBA were not markedly affected by NCM given in drinking water (1000-1800 ppm) until 14-16 months of age. These results confirm NCM's general lack of activity as an in vivo toxicant, but show that under certain circumstances it may enhance or suppress tumor development.
Subject(s)
Cimetidine/analogs & derivatives , Neoplasms, Experimental/chemically induced , 9,10-Dimethyl-1,2-benzanthracene , Animals , Cimetidine/pharmacology , Cocarcinogenesis , Lung Neoplasms/chemically induced , Mice , Skin Neoplasms/chemically induced , UrethaneABSTRACT
N-Hydroxylaminopurines are highly mutagenic for growing as well as resting Salmonella typhimurium strain TA100 and to a lesser extent for strain TA98. Aminopurines, under similar conditions, are not mutagenic. N-Methylhydroxylaminopurine, under similar conditions, exhibits only minimal activity. The results are taken to indicate that unlike non-hydroxylated aminopurines, N-hydroxylaminopurines exert their mutagenicity not by acting as base analogs but by direct covalent binding with DNA-guanine.
Subject(s)
Adenine/analogs & derivatives , Carcinogens , Adenine/metabolism , Chemical Phenomena , Chemistry , DNA/metabolism , Purines/metabolism , Salmonella typhimurium/drug effects , Structure-Activity RelationshipABSTRACT
Cimetidine (CM), a drug widely prescribed for ulcers, readily undergoes nitrosation to form nitrosocimetidine (NCM), a genotoxic agent. In a test of the chronic effects of NCM in mice, (C57BL/6 X BALB/c)F1 mice were exposed chronically to NCM (113 or 1130 ppm) in the drinking water from preconception through prenatal and neonatal development and adult life. Each group consisted of 40 to 80 mice of each sex, and median survival time was 27 months. Other groups were given CM alone or in combination with NaNO2 (184 or 1840 ppm), or NaNO2 alone. None of the chemical treatments had large effects on reproductive parameters, survival, or incidence of nonneoplastic lesions. CM treatment was associated with a small but significant increase in incidence of lymphomas in females, 41 of 59 (69%), compared with 31 of 66 controls (47%, P = 0.01). No females receiving either dose of NCM developed mammary carcinomas (0 of 91), compared with an incidence of four of 66 controls (6%, P = 0.03). Males given the high-dose combination of CM and NaNO2 showed a higher incidence of lung tumor bearers than controls (71 of 79 versus 30 of 52, P less than 0.01) and also experienced a significant, dose-dependent increase in numbers of large lung tumors (greater than 1 cm in diameter), lung carcinoma, and metastatic lung tumors. Females given the higher dose of NCM had significantly greater incidence of mice with large lung tumors than controls (nine of 41 versus three of 66, P = 0.009). The possibility of carcinogenicity of cimetidine, nitrosocimetidine, and cimetidine plus nitrite is discussed.