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At least 19 recordsLinked to original sources

PubMed2026

Magrolimab Plus Azacitidine Versus Placebo Plus Azacitidine in Patients With Untreated Higher-Risk Myelodysplastic Syndromes: The Phase III ENHANCE Study.

PURPOSE: To evaluate the efficacy and safety of the cluster of differentiation 47-targeted antibody magrolimab plus azacitidine (Magro/Aza) versus azacitidine alone in treatment-naïve patients with higher-risk myelodysplastic syndromes (MDS) in the phase III ENHANCE study (ClinicalTrials.gov identifier: NCT04313881). METHODS: Based on the Revised International Prognostic Scoring System, patients with intermediate- to very-high-risk MDS were randomly assigned to receive Magro (1 mg/kg on days [D]1 and 4; 15 mg/kg on D8; 30 mg/kg on D11 and D15, and then once per week for five doses, followed by 30 mg/kg maintenance doses once every 2 weeks)/Aza (75 mg/m2 daily on D1-7 or on D1-5 and 8-9 in 28-day cycles) or matched placebo plus azacitidine (Placebo/Aza). Dual primary end points were complete remission (CR) rate (per 2006 International Working Group criteria) and overall survival (OS). RESULTS: At final analysis, 539 patients were randomly assigned to Magro/Aza (n = 268) or Placebo/Aza (n = 271) arms. Baseline characteristics were generally well balanced between treatment arms. In the Magro/Aza versus Placebo/Aza arms, the CR rate was 21.3% versus 23.6% (odds ratio, 0.876 [95% CI, 0.585 to 1.312]; P = .5218), and median OS was 15.9 versus 18.6 months (hazard ratio, 1.203 [95% CI, 0.947 to 1.528]; P = .1299). Magro/Aza had a higher incidence of grade ≥3 adverse events (AEs; 92.8% v 79.2%), AE-associated study drug discontinuations (24.0% v 12.1%), serious AEs (71.9% v 51.5%), and fatal AEs (15.2% v 9.8%) versus Placebo/Aza. CONCLUSION: ENHANCE did not meet the primary end points of CR rate and OS, and showed more frequent severe AEs in patients treated in the Magro/Aza arm.

Humans↗

PubMed2026

Azacitidine-Venetoclax or Induction Chemotherapy for Acute Myeloid Leukemia.

BACKGROUND: Induction chemotherapy has long been a key component of curative therapy for fit patients with acute myeloid leukemia (AML), despite its frequently severe side effects and substantial health care utilization. For patients who are ineligible for induction chemotherapy, hypomethylating therapy plus venetoclax is the standard treatment owing to its efficacy and side-effect profile. METHODS: In this multicenter, phase 2 trial, we randomly assigned, in a 1:1 ratio, previously untreated adults with AML who were eligible for induction chemotherapy to receive either azacitidine plus venetoclax or induction chemotherapy. Patients with core binding factor fusions, mutations in the gene encoding FMS-like tyrosine kinase 3 (FLT3), or mutations in the gene encoding nucleophosmin-1 (NPM1; unless the patient was ≥60 years of age) were excluded. The primary end point was event-free survival. RESULTS: A total of 172 patients underwent randomization, with 86 patients assigned to each group. The median age of the patients was 64 years. A total of 72% of the patients had adverse-risk disease according to the European LeukemiaNet 2022 classification. At a median follow-up of 21.9 months, the median event-free survival was 14.5 months (95% confidence interval [CI], 10.4 to 24.4) in the azacitidine-venetoclax group, as compared with 6.2 months (95% CI, 4.1 to 10.1) in the induction chemotherapy group, corresponding to a hazard ratio for event or death of 0.57 (95% CI, 0.39 to 0.84; P = 0.002 by the stratified log-rank test). Infection of grade 3 or higher occurred in 28% of the patients (95% CI, 19 to 39) receiving azacitidine-venetoclax and in 41% of those (95% CI, 30 to 52) receiving induction chemotherapy; hemorrhage of grade 3 or higher occurred in 2% (95% CI, 0.3 to 8) and 12% (95% CI, 6 to 20), respectively. CONCLUSIONS: In this phase 2, randomized trial, azacitidine-venetoclax therapy led to significantly longer event-free survival than induction chemotherapy among induction-eligible patients with AML. (Funded by AbbVie and others; PARADIGM ClinicalTrials.gov number, NCT04801797.).

Adult↗

PubMed2026

Health-system burden of higher-risk myelodysplastic syndromes in England: a literature-based micro-cost analysis.

OBJECTIVES: To quantify the per-patient-per-month (PPPM) cost for each phase of care in higher-risk myelodysplastic syndromes (HR-MDS) and the overall cost of a base-case (illustrative) non-curative management pathway followed by a patient with HR-MDS in England. DESIGN: We conducted a retrospective, literature-based, micro-costing analysis from the National Health Service (NHS) England provider perspective using published sources and publicly available price lists. No individual-patient data were used. Based on literature, a base-case management pathway followed by a patient with HR-MDS was defined as a diagnostic work-up at month 0, 12 cycles of azacitidine (given for 7 days in each 28-day cycle), 5 months of post-hypomethylating agent (HMA) failure supportive care and 1 month of terminal care. SETTING: Healthcare resource utilisation was analysed for adults with HR-MDS who received first-line azacitidine in routine practice if cycle-level or phase-level transfusion and admission rates were reported in the literature. Patients who required allogeneic haematopoietic stem cell transplantation or whose HR-MDS transformed to acute myeloid leukaemia were excluded because the diagnostic and/or therapeutic pathways differ. Unit costs for 2024/2025 were taken from published English national sources and an English trust tariff. RESULTS: PPPM costs were £8721.58 during active azacitidine therapy, £5399.58 after HMA failure and £12 554.58 for hospital-dominant terminal care; a one-off diagnostic work-up with genomics cost £2710 to £2810. The total cost for the base-case management pathway was £146 921 per patient. An alternative pathway excluding genomic testing and assuming hospice-dominant terminal care reduced the total cost to approximately £136 840 to £140 990, depending on whether the lower or upper bound of hospice bed-day costs is applied. CONCLUSIONS: The direct NHS-provider cost burden of this non-curative HR-MDS management pathway is concentrated in azacitidine acquisition and administration during active treatment, transfusions and admissions after HMA failure and setting-dependent costs at the end of life. The total cost for the illustrative management pathway followed by a patient with HR-MDS (£146 921) is of a similar order to the estimate in the National Institute for Health and Care Excellence technology appraisal for azacitidine uprated to £124 848 for 2024/2025. This comparison is provided for context only and should not be interpreted as validation of the present model, given differences in population, model structure, treatment duration and price year. The phase-specific PPPM estimates can inform, subject to local validation and scenario testing, UK budget-impact analyses, service planning and future economic models.

Humans↗

PubMed2026

Genomic Evolution of Myeloproliferative Neoplasms and Therapy-Associated Mutagenesis.

UNLABELLED: Philadelphia-negative myeloproliferative neoplasms are chronic blood neoplasms. Treatments control blood counts, but disease can progress to myelofibrosis or acute myeloid leukemia. We performed longitudinal whole-genome and targeted sequencing in 30 patients, integrating clonal dynamics with 7,986 blood counts and clinical histories. Distinct evolutionary patterns distinguished stable from progressive disease, with leukemic transformation arising via TP53 loss, stepwise driver mutation acquisition within complex clones, or emergence of independent leukemic clones. In contrast, stable disease showed long-term clonal equilibrium without new drivers. Phylogenetic analysis using 203 whole-genomes of hematopoietic colonies revealed age-appropriate polyclonal hematopoiesis in triple-negative essential thrombocythemia and germline predisposition to thrombocytosis, supporting non-neoplastic origins. Therapy-associated mutagenesis was observed, including C > G mutations following azacitidine and characteristic T > A/T > G after hydroxycarbamide exposure in blood cells, although not in skin where UV damage predominated. These findings demonstrate that progression is genomically encoded years in advance and support serial monitoring and further study of treatment-related mutagenesis. SIGNIFICANCE: Longitudinal whole-genome sequencing shows MPN progression is genomically encoded years before clinical transformation, with distinct evolutionary routes to leukemia and MF. It identifies DNA mutagenesis associated with HC and 5-azacitidine, suggests some triple-negative cases are nonclonal, and supports serial clinical genomic monitoring for improved risk stratification and long-term management. See related commentary by Agarwal and Sankaran, p. 1724.

Humans↗

PubMed2026

Genome agnostic, multi-level non-oncogene addiction-based systems pharmacology for rescuing metastatic relapsed/refractory neoplasias.

Rescue therapies for relapsed/refractory (r/r) metastatic neoplasias present significant unmet needs. Tumor tissue editing regimen for 13 r/r tumor types, carcinomas, sarcomas and hematologic neoplasias, included in 15 phase I/II trials, nuclear/cytokine receptor agonists, pioglitazone, plus/minus dexamethasone or all-trans retinoic acid or interferon-α to counterbalance tumor tissue homeostasis and reprogramming of cancer hallmarks, stress response inhibitors, COX-2 inhibitor, everolimus, lenalidomide, or clarithromycin, and a stress response inducer, low-dose metronomic chemotherapy with treosulfan, trofosfamide, capecitabine, or azacitidine. CR in three, cCR in another five r/r neoplasias, as the best response occurred after transcriptional reprogramming of cancer hallmarks, inflammation control or differentiation induction. Receptor agonist combinations for cCR induction can be identical among quite different tumor types and diversified within the same tumor histology. Data reveal ubiquitous, differential transcriptional access to non-oncogene addiction (NOA) networks that cope with cancer hallmarks/stress responses and three levels of therapeutic NOA targeting. (1) Agonists of nuclear/cytokine receptor NOAs critically target tumor identity and viability, while (2) transcriptional reprogramming of NOA networks that contribute to tumor tissue addiction, thereby genome-agnostically counteracting oncogene addictions. (3) Targeting edited NOAs may improve long-term outcome with CR/cCR (everolimus, IMiD). Transcriptionally accessible NOA targets offer high specificity, modest toxicity profile, low cost of therapy and outpatient treatment, independent of comorbidities. Adaptive targeting of the transcriptomic landscapes of tumor cell compartments breaks tumor tissue addiction and overcomes M-CRAC, post-therapy metastasis, cancer cell recolonization, acquired resistance and genetic heterogeneity. Thus, editing approaches provide a template for controlling metastatic r/r tumors. In the future, diagnostics of NOA networks and transcription factors involved in tumor tissue addiction may be as valuable for therapy selection as histological/molecular genetic tumor typing for the establishment of personalized hematology/oncology.

Hodgkin’s lymphoma↗

PubMed2025

Diagnostic and Monitoring Strategies for VEXAS Syndrome: Evaluating Sanger Sequencing, NGS, and the SWIM-Score.

VEXAS syndrome is an adult-onset autoinflammatory disorder caused by somatic UBA1 variants, but there are no standardized criteria for genetic testing or diagnostics. This study compared Sanger sequencing and next-generation sequencing (NGS) for detecting UBA1 variants in patients with suspected VEXAS, assessed the ability of Sanger sequencing to estimate variant allele fractions (VAFs), and evaluated the Maeda et al. scoring system for selecting patients for genetic testing in a primary cohort and a validation cohort. In the primary cohort of 104 patients, Sanger sequencing identified VEXAS variants in 12%, with no additional cases detected by NGS. Sanger sequencing accurately quantified VAFs ranging from 0.1 to 0.9. In a small longitudinal subset (n = 3), VAFs in blood correlated with CRP levels, increased over time despite various treatments, but decreased in two patients after initiation of Azacitidine treatment. The novel parameters, VAF in myeloid cells and VEXAS cell concentration, showed promise as exploratory markers for patient monitoring. The Maeda-score, requiring a threshold score of 2 for 100% sensitivity, exhibited low specificity-29% in the primary cohort and 41% in the validation cohort (n = 62, with 2 carrying VEXAS variants). In contrast, the simplified SWIM-score-based on Skin involvement, Weight loss, Inflammation, and Macrocytic anemia-achieved 100% sensitivity in both cohorts, with higher specificities of 47% and 65%, respectively. In conclusion, Sanger sequencing reliably detected UBA1 variants and quantified VAFs. Monitoring VAF and VEXAS cell concentration may track disease progression, and the SWIM-score demonstrated potential for accurately selecting patients for UBA1 testing.

Humans↗

PubMed2026

Late acquisition of BCR::ABL1 during clonal evolution of SAMD9-associated MDS with phenotypic shift from AML to B-ALL.

We describe a unique case of SAMD9-associated myelodysplastic syndrome (MDS) with monosomy 7 that evolved over 16 years into BCR::ABL1-positive acute myeloid leukemia (AML) and subsequently manifested as B-cell acute lymphoblastic leukemia (B-ALL). Genomic analysis at AML diagnosis revealed a germline SAMD9 mutation together with somatic RUNX1 and PPM1D mutations, supporting stepwise clonal evolution, with BCR::ABL1 emerging as a late leukemogenic event. The dominant leukemic population at AML onset showed myeloid morphology and immunophenotype, whereas a minor CD19+CD10+ population was already detectable. Following venetoclax and azacitidine therapy, the dominant leukemic phenotype shifted to B-ALL while retaining BCR::ABL1 positivity. Detection of the Philadelphia chromosome in mature neutrophils at both AML onset and ALL relapse supported multilineage involvement of a multipotent BCR::ABL1-positive clone. Ponatinib achieved disease control. This case highlights late acquisition of BCR::ABL1 during SAMD9-associated clonal evolution and therapy-driven phenotypic shift within a shared Ph-positive leukemic stem-cell hierarchy.

Humans↗

PubMed2026

Targeting DNA Methylation: New Paradigms and the Advent of Gene-Selective Tools.

DNA methylation can function as a toxic alkylation reaction exploited by chemotherapeutic agents to induce cancer cell death. However, finely tuned DNA methylation plays a fundamental role in cellular physiology, particularly in the epigenetic regulation of gene expression. Once thought to act solely as a repressor of gene transcription, its functional role has since been elucidated as genomic locus-specific and deeply connected with other epigenetic factors. Following the clinical approval of DNA methyltransferase inhibitors, such as Azacitidine and Decitabine, for the treatment of hematological malignancies, considerable efforts have been devoted to developing pharmacological tools that modulate epigenetic DNA methylation. However, the lack of gene selectivity in these agents limits their therapeutic efficacy and increases off-target toxicity. Moreover, the non-gene-selective nature of current DNA methylation-targeting molecules fails to meet the standards required to discern the nuanced roles of DNA methylation across diverse pathophysiological contexts and genomic loci, particularly in an era where next-generation sequencing and omics technologies enable high-resolution epigenetic analyses. In this review, we examine the mechanisms and roles of DNA methylation in epigenetic regulation, evaluate the current landscape of DNA methylation modulators, from traditional DNMT inhibitors to cutting-edge CRISPR-dCas9 fusion systems and protein-protein interaction disruptors, and discuss their clinical relevance. Finally, we emphasize the need for precise, locus-specific tools to advance both cancer research and therapeutic strategies.

Humans↗

PubMed1976

A comparative clinical trial of 5-azacytidine and guanazole in previously treated adults with acute nonlymphocytic leukemia.

Adults with previously treated acute nonlymphocytic leukemia received either 5-azacytidine or guanazole in a randomized study. Eighteen patients were treated with 5-azacytidine at a dosage of 200-250 mg/m2/day X 5 intravenously (i.v.) and six achieved a remission (five complete). The median duration of complete remission was 100 days. Among the 12 patients who received guanazole, at a dosage of 25-30 g/m2/day X 5 by continuous i.v. infusion, only one partial remission ensued. Pm 600 WBC/mm3) than nonresponders (median 1700 WBC/mm3). Both the time taken to reach the nadir white blood coung (median, 14 days) and theduration of the nadir (median, 17 days) were long after each course of 5-azacytidine, particularly for those patients who achieved a remission. Principal toxicities seen after 5-azacytidine administration were gastrointestinal tolerance, fever, and neuromuscular toxicity. Fever was the principal toxicity observed after guanazole therapy; one patient developed erythema nodosum with arthralgias and another, recurrent pulmonary infiltrates. Survival from the start of therapy was clearly longer for the patients receiving 5-azacytidine (median 140 days) because of the prolongation of survival seen in the responding patients (median 266 + days). 5-Azacytidine has significant activity as an induction agent in adults with acute nonlymphocytic leukemia, but guanazole does not appear to be of particular value for patients with this disease.

Acute Disease↗

PubMed1978

Diffuse pulmonary malignant mesothelioma: response to doxorubicin and 5-azacytidine.

A 46-year-old patient who developed a right pleural mesothelioma 18 years after asbestos exposure was found to have diffuse reticular nodular infiltrates in both lungs. Lung biopsy by fiberoptic bronchoscopy revealed alveolar and interstitial spread of the neoplastic cells. A dramatic clinical and radiologic response occurred after treatment with a combination of doxorubicin (Adriamycin) and 5-Azacytidine.

Azacitidine↗

PubMed1978

5-azacytidine in acute leukemia.

101 patients with acute leukemia in relapse were treated with 5-azacytidine according to three schedules: Regimen A--300 mg/m2(day divided intravenously at 8 hour intervals for 5 days; Regimen B--750 mg/m2 as a single iv pulse dose administered at 2 to 3 weeks intervals; and Regimen C--300 mg/m2/day by continuous infusion daily for 5 days. Twelve patients achieved a complete remission (CR) and six achieved a partial remission (PR) for an overall 18% response rate. Of 78 patients receiving an adequate trial the response rate was 23%. An average of 1.5 courses and a median of 5 weeks were necessary to achieve a response. The median duration of CR patients was 21 weeks and for PR patients it was 5 weeks. Response rates were 24% for Regimen A, 0 for Regimen B, and 1 of 8 for Regimen C. The CR rate for AML and AMML was 13%. Two of eight AMoL patients achieved a CR. Only 2 of 23 ALL patients responded, one of whom achieved a CR. Toxicity included moderate to severe nausea and vomiting, diarrhea, stomatitis, skin rash, and prolonged myelosuppression. 5-azacytidine has significant activity in the acute nonlymphoblastic leukemias.

Acute Disease↗

PubMed1992

Phenotypic and functional similarities between 5-azacytidine-treated T cells and a T cell subset in patients with active systemic lupus erythematosus.

OBJECTIVE: Antigen-specific CD4+ T cells treated with DNA methylation inhibitors become autoreactive, suggesting a novel mechanism for autoimmunity. To test whether this mechanism might be involved in systemic lupus erythematosus (SLE), phenotypic markers for the autoreactive cells were sought. METHODS: Cloned normal T cells were treated with the DNA methylation inhibitor 5-azacytidine (5-azaC) and studied for altered gene expression. T cells from patients with active SLE were then studied for a similar change in gene expression, and cells expressing the marker were tested for autoreactivity. RESULTS: 5-azaC-treated normal T cells had increased CD11a (leukocyte function-associated antigen 1 alpha) expression relative to other membrane molecules. A T cell subset with similar CD11a expression was found in patients with active SLE. This subset contained cells that spontaneously lysed autologous macrophages, with a specificity similar to that of 5-azaC-treated cells.

Antigens, CD↗

PubMed1992

Expression of the complement regulatory proteins CD21, CD55 and CD59 on Burkitt lymphoma lines: their role in sensitivity to human serum-mediated lysis.

On a panel of nine human B cell lines we showed that the expression of the complement regulatory factors complement receptor type 2 (CR2; CD21), decay-accelerating factor, (DAF; CD55) and homologous restriction factor (HRF20, CD59) is not correlated. All lines expressed DAF, six lines carried detectable amounts of CR2 and three carried HRF20. Upon incubation in human serum, under conditions which allowed the activation of complement through the alternative pathway, the CR2-carrying lines bound C3 fragments and two of them (Ramos and one of its two sublines) were damaged. These two lines had the lowest DAF expression, less than 50% of the cells reacted with the IA10 monoclonal antibody. By modulating the expression of the complement regulatory molecules, the lytic sensitivity of the B cell lines could be altered. Blockade of DAF on the HRF20-, CR2+ lines with the specific monoclonal antibodies increased their sensitivity to lysis by human serum. With the DAF- and HRF20+ cells significant lytic effect was obtained only when they were pretreated with both of the specific antibodies. Interferon-gamma or tumor necrosis factor-alpha treatment elevated the amount of CR2 on the low-CR2 expressor line (Ramos/HR1K) which thereafter bound higher amounts of C3 fragments and was lysed when incubated in human serum. This line had relatively low DAF level and lacked HRF20. The cytokine treatment did not alter the expression of these molecules. The CR2+ Ramos and the CR2- Rael cells were treated with 5-azacytidine which induced HRF20 and increased DAF expression. In parallel with this change Ramos cells became resistant to C-mediated lysis. The experiments with the panel of human B cell lines showed thus that cytolysis through activation of complement in homologous serum can be regulated at several steps by cell surface molecules. While expression of CR2 was required for C3 fixation, DAF and HRF20 inhibited lysis. By independent modulation of the quantities of these molecules, cells acquired or lost their sensitivity.

Antibodies, Monoclonal↗

PubMed1992

Tumor-associated karyotypic lesions coselected with in vitro macrophage differentiation.

Several cytogenetic lesions in chromosomes 2, 5, 12, and 16 have been repeatedly coselected with in vitro macrophage differentiation in a clonal murine thymic tumor cell line. Parental-type subclones, which show an extremely immature hemopoietic phenotype, do not carry the aberrations. The frequency of the stable differentiated variants is elevated by 5-azacytidine and bromodeoxyuridine, consistent with chromosome breakage being responsible for the phenotype. The frequency is also raised by dexamethasone. Since variants are 300-3,000-fold more resistant to dexamethasone than parental clones, we interpret this to be largely due to selection. Three of the lesions, on chromosome 2, match those previously described as associated specifically with in vivo-generated murine myeloid tumors, induced by X irradiation and corticosteroid treatment. Several implications follow from these observations. (1) In vitro differentiation in clonal tumor cell lines can be used to select for tumor-associated lesions. This should allow genetic and molecular analysis of the chromosome 2 lesions and of others that may pinpoint genes critical to macrophage differentiation and transformation. (2) Myeloid and lymphoid tumors that occur in response to X irradiation may diverge from a common initiating tumor. (3) The hemopoietic lineage switch phenomenon, previously described by several authors, may be caused by similar or identical chromosome aberrations.

Abelson murine leukemia virus↗

PubMed1992

Enhancement of hepatitis-B surface-antigen expression by 5-azacytidine in a hepatitis-B-virus-transfected cell line.

The human hepatoblastoma-derived cell line HB611 secretes hepatitis-B surface antigen (HBsAg) and hepatitis-B e antigen (HBeAg) into the medium. Hepatitis-B-virus (HBV) DNA integrated into the cellular genome was found to be hypermethylated. When the cells were treated with 5-azacytidine for 3 days, the level of HBsAg in the medium increased, while the level of HBeAg remained constant. The level of alpha-fetoprotein (AFP) decreased with the 5-azacytidine treatment. Southern blot analysis of DNA digested with HpaII or MspI showed that 5-azacytidine treatment resulted in hypomethylation of the integrated HBV DNA, suggesting that 5-azacytidine increased HBsAg production in the cells through hypomethylation of the HBV genomic DNA.

Azacitidine↗

PubMed1976

A phase I study of 5-azacytidine (NSC-102816).

5-Azacytidine was administered daily to 12 patients in a five-day schedule and to 15 patients in a weekly schedule as part of a phase I trial. The daily dose ranged from 50 mg/m2 to 158 mg/m2 and the weekly dose, from 200 mg/m2 to 633 mg/m2. The maximum total dose was 2000 mg in the daily schedule and 3775 mg in the weekly schedule. The major toxicity was gastrointestinal, with nausea and vomiting occurring in all patients in this study. Myelosuppression was less frequently encountered and appeared to be related to the increase in 5-azacytidine dose. Patients receiving 5-azacytidine in a weekly schedule of administration appeared to tolerate the drug better and to be more willing to continue their therapy.

Azacitidine↗

PubMed1977

Alterations in differentiation and pyrimidine pathway enzymes in 5-azacytidine resistant variants of a myoblast line.

5-azacytidine at concentrations higher than 5 muM inhibited the differentiation of a rat myoblast line in vitro. It was also somewhat cytotoxic at this level. Variants resistant to the cytotoxic effect of 5-azacytidine were obtained which were simultaneously unable to differentiate into myotubes and exhibited altered morphology. These characteristics were retained by the variants when subcultured in the absence of the drug for over 700 generations. Several of the azacytidine resistant cells were more susceptible than the parental line to the lethal action of 5-bromodeoxyuridine and adenosine, but not that of cytosine arabinoside, ouabain or 8-azaguanine. The variants were capable of transporting uridine, thymidine and 5-azacytidine. The uridine kinase activity was one-half to one-third of than in the parental cells but it was not missing completely in any of the variants. Two independently isolated variants selected for detailed study showed a 2- to 3-fold increase in the activity of orotidylic acid decarboxylase. This enzyme in the variants in contrast to that of the parental cells was completely insensitive to the inhibitory effect of a nucleotide generated from ATP and 5-azacytidine in cell extracts (probably 5-azacytidine monophosphate). These observations point to the possibility the 5-azacytidine resistance arises in myoblasts due to an alteration of the components of two target pathways of this drug, viz., the de novo pyrimidine pathway and an undefined sequence leading to the synthesis of membrane components.

Adenosine↗

PubMed1992

Repression of SV40 T oncoprotein expression by DMSO.

SV40 large T oncoprotein-transformed murine mesenchymal 3T3 T stem cells (CSV3 cells) can be induced to growth arrest and then differentiate into adipocytes. When differentiation occurs, SV40 T oncoprotein expression is repressed (Estervig et al., J Virol 63:2718, 1989). To determine if repression of T oncoprotein expression can also be induced pharmacologically, the effect of a variety of agents that have been reported to effect differentiation in various cell types but not in 3T3 T or CSV3 cells was tested. This rationale suggests that if any of these agents repress T oncoprotein expression in CSV3 cells, then the results would establish that repression of T oncoprotein expression can be mediated by mechanisms independent of overt differentiation. The results show that dimethylsulfoxide (DMSO) is the only agent tested that represses T oncoprotein expression in CSV3 cells. Repression occurs in a dosage-dependent manner within 24-96 hours after exposure to DMSO. The effect of DMSO on T oncoprotein expression is mediated by posttranslational mechanisms that decrease the stability of the T oncoprotein. DMSO-induced repression of T oncoprotein expression is also associated with reversion of the transformed phenotype in CSV3 cells as demonstrated by the loss of responsiveness to a specific transformation-associated mitogen. These data support the conclusion that the pharmacological repression of T oncoprotein expression represents a form of cancer suppressor activity that can be mediated by a distinct molecular mechanism.

Acetamides↗