MGMT expression

In our cohort, MGMT expression seems helpful as a biomarker of good prognosis (low-grade and absence of muscle invasion). A heterogeneous methylation pattern in the MGMT gene requires additional investigation to elucidate its potential implications.

This meta-analysis highlights that Lev use may prolong survival in IDH wild-type GB patients. Further randomized trials are needed to confirm these findings and identify subgroups benefiting most from Lev treatment.

Targeting higher isoform Var2 of hnRNPA1 specifically induces chemosensitization in MGMT expressed Temozolomide resistant U87MG as well as in MGMT non-expressed LN229 TMZ resistant cells.

AP-2α activation by gene overexpression or RA treatment reveals the suppressive effects on glioma relapse, providing a novel therapeutic strategy against malignant refractory gliomas.

Additionally, we explore the benefits of combining Temozolomide and immunotherapy in MGMT hypermethylated subgroups. Future studies can focus on optimizing Temozolomide administration to induce specific immunomodulatory changes.

MiRNA is a promising epigenetic modulator that might be utilized in HGG management. A better understanding on the role of miRNA in HGG patients might be able to improve clinical outcome.

This study serves as a proof of concept for the utilization of CRISPR-based gene suppression to overcome TMZ resistance and enhance the lethal effect of TMZ in glioblastoma tumor cells.

In resistant SF763 mouse tumor xenografts, LND plus ACNU significantly inhibited tumor growth with fewer side effects than ACNU alone. Finally, we proposed a new "HMAGOMR" chemo-sensitizing mechanism through which LND may act as a potential chemo-sensitizer to reverse ACNU resistance in glioblastoma: moderate inhibition of hexokinase (HK) activity (H); mitochondrial dysfunction (M); suppressing adenosine triphosphate (ATP)-dependent drug efflux (A); changing redox homeostasis to inhibit GSH-mediated drug inactivation (G) and increasing intracellular oxidative stress (O); downregulating MGMT expression through intracellular acidification (M); and partial inhibition of energy-dependent DNA repair (R).

We first demonstrated that muscone suppressed TOP2A expression through the EGFR/Integrin β1/FAK pathway, hence restoring anoikis sensitivity in TMZ-resistant GBM cells. These data suggest that muscone may be a promising co-therapeutic agent for enhancing GBM treatment, particularly in cases of TMZ-resistant GBM with elevated TOP2A expression.

GBM 101.8 is a reliable model for further investigation due to its similarity to high-grade human GBMs, while GBM 11-9-2 and GBM 14-4-5 correspond to Grade 2-3 gliomas.

The regulation of MGMT ubiquitination by USP19 plays a critical role in DNA methylation damage repair and GBM patients' temozolomide chemotherapy response.

O6-methylguanine-DNA-methyltransferase (MGMT) promoter methylation status is the central molecular biomarker linked to both the response to temozolomide, the standard chemotherapy drug employed for GBM, and to patient survival...Our method provides promising results, reducing dimensionality (by more than 95%) when employed on two large-scale proteomic datasets (7k SomaScan® panel and CPTAC) for all our analyses. The computational results indicate that the proposed approach provides 14 shared serum biomarkers that may be helpful for diagnostic, prognostic, and/or predictive operations for GBM-related processes, given further validation.

The following systematic review details a comprehensive investigation of the current literature and highlights several potential key CpG sites that demonstrate significant association with OS, PFS, and MGMT expression. However, the relationship between extent of MGMT promoter methylation and survival may be non-linear and could be influenced by potential CpG hotspots, the extent of methylation at each CpG site, and MGMT enhancer methylation status. There were several limitations within the studies such as smaller sample sizes, variance between methylation testing methods, and differences in the various statistical methods to test for association to outcome. Further studies of high impact CpG sites in MGMT methylation is warranted.

Lastly, EPIC-0628 enhanced TMZ efficacy in GBM in vitro and vivo. Hence, this study provided evidence for the combination of epigenetic drugs EPIC-0628 with TMZ for GBM treatment through the above mechanisms.

P2/3, N=147, Active, not recruiting, National Cancer Institute (NCI) | N=485 --> 147 | Trial completion date: Aug 2024 --> Mar 2025 | Trial primary completion date: Aug 2024 --> Apr 2023

The increase in H3K9ac appears to enhance the recruitment of the transcription factor SP1 to its binding sites within the MGMT locus, consequently upregulating MGMT expression and driving TMZ resistance in GBM.

Methylation of the MGMT promoter, which predicts the response to temozolomide, is a well-established prognostic marker for glioblastoma...Finally, we report that the expression of DIAPH3 is at least partially regulated by the methylation of three CpG sites in the promoter region. We propose that combining the DIAPH3 expression with MGMT methylation could offer a better prediction of survival and more adapted postsurgical treatment for patients with MGMT-methylated glioblastoma.

Spherical growth, however, was positively correlated with high levels of Hif1α, CDK4, PTEN, and PDGFRβ, whereas correlations with stemness factors or MGMT (MGMT expression and promoter methylation) were low or missing. Factors highly expressed by all SLGC lines, irrespective of their degree of stemness and growth behavior, are Cathepsin-D, CD99, EMMPRIN/CD147, Intβ1, the Galectins 3 and 3b, and N-Cadherin.

The effectiveness of temozolomide (TMZ) treatment in GBM is linked to the methylation status of O6-methyl-guanine DNA methyltransferase (MGMT) promoter...These findings contribute to a better understanding of the immune response in MGMT-H tumors, emphasizing their potential for immunotherapy. Further studies are warranted to investigate on the mechanisms of MGMT expression and antitumor immunity.

The CORT/NF-κB/MGMT axis might be regarded as a molecular mechanism contributing to the resistance of glioma to TMZ. Our data also suggest that CORT regulates the viability and metastatic potential of glioma cells, independent of its effects on TMZ resistance, providing evidence of novel therapeutic targets for glioma that should be evaluated in further studies.

We conclude that chemotherapy with TMZ can be dramatically enhanced by delivering at the daily maximum of tumor Bmal1 expression and minimum of MGMT activity and that scoring MGMT methylation status requires controlling for time of day of biopsy.

Temozolomide (TMZ) is the most preferred and approved chemotherapeutic drug for either first- or second-line chemotherapy for glioma patients across the globe...Furthermore, MGMT promoter methylation, stability of MGMT protein, and related subsequent adaptive responses are also important contributors to strategic developments in glioma therapy. With applications to its identification as a prognostic biomarker, thus predicting response to advanced glioma therapy, this review aims to concentrate on the mechanistic role and regulation of MGMT gene expression at epigenetic, transcriptional, post-transcriptional, and post-translational levels functioning under the control of multiple signaling dynamics.

In the present study notable depletion of survivality was established in the Imatinib resistance patients manifesting genetic malfunction of BCR-ABL transcripts among the North East Indian inhabitants and advocating for the expansion of the disease.

Western blot analysis indicated that treatment of GBM cells with CTS combined with TMZ more significantly decreased the expression of MGMT and STAT3, than that with TMZ alone. Combined treatment with CTS and TMZ might be an effective option to overcome the chemoresistance of GBM cells in a long-term treatment strategy.

Temozolomide (TMZ) offers substantial therapeutic benefits for glioblastoma (GB), yet its efficacy is hindered the development of chemoresistance...In conclusion, a novel CREB/LINC00473/CEBPα/MGMT pathway was revealed in the GB TMZ-resistance formation. In addition, an exosome-based mechanism of chemoresistance transmission was revealed, which suggested that LINC00473 could be used as a novel therapeutic target for GB.

It was further determined that chronic low dose of Cr(VI) exposure-transformed BEAS-2B cells display impaired DNA damage repair capacity and a high sensitivity to the toxicity of the alkylating chemotherapeutic drug Temozolomide...Further mechanistical studies revealed that chronic low dose of Cr(VI) exposure down-regulates MGMT expression through epigenetic mechanisms by increasing DNA methylation and histone H3 repressive modifications. Taken together, these findings suggest that epigenetic down-regulation of a crucial DNA damage repair protein MGMT contributes significantly to the genotoxic effect and cell transformation caused by chronic low dose of Cr(VI) exposure.

Similarly, across cancers, MGMT has been identified as the major contributor of chemoresistance against DNA alkylating agents like Temozolomide (TMZ)...Mechanistically, luciferase reporter and chromatin-immunoprecipitation assays demonstrated that p68 interacts with the MGMT promoter via TCF4-LEF, RelA and SP1 sites to enhance its transcription. To the best of our knowledge, this is the first report of p68 as a transcriptional co-activator of MGMT promoter and our study identifies p68 as a novel and master regulator of MGMT gene expression.

Overall, our newly developed isogenic rat and mouse glioma models recapitulate MGMT-dependent TMZ sensitivity and provide useful preclinical tools for studying MGMT as a biomarker and potential therapeutic target in GBM. In addition, these syngeneic models facilitate studies on the immune modulation of chemotherapeutic agents in the context of MGMT expression and allows for testing of chemoimmunotherapy combinations.

TRC102 (methoxyamine), a small molecule DNA base-excision repair (BER) inhibitor, reverses temozolomide (TMZ) resistance in preclinical glioma models...If sufficient activity was identified, arm 2 was planned in bevacizumab-refractory patients... rGBM patients with elevated levels of MPG and DDR molecular signature may have impaired BER and respond better to TRC102+TMZ.

We identified an interface between DNA damage response and miRNA degradation that mediate intra-tumoral heterogeneity and subsequent temozolomide resistance. This resistance mechanism is distinct from modulation of the mean MGMT expression of the population.

γδ T cells successfully infused with peripheral TMZ-based lymphodepletion evidenced with near or below normal range T, B, and NK subsets for up to 1 year. DRI T cells have manageable toxicity with encouraging trend in PFS with enriched γδ T cell remaining despite peripheral lymphodepletion.

TRC102 (methoxyamine), a small molecule DNA base-excision repair (BER) inhibitor, reverses temozolomide (TMZ) resistance in preclinical glioma models...If sufficient activity was identified, arm 2 was planned in bevacizumab-refractory patients... rGBM patients with elevated levels of MPG and DDR molecular signature may have impaired BER and respond better to TRC102+TMZ.

Further, we provide novel evidence that the demethylating agent 5-Azacitidine (5-Aza) reactivates TUSC3 expression in MGMT-M GSCs, whereas the combination of 5-Aza and MGMT inhibitor Lomeguatrib is necessary for TUSC3 reactivation in MGMT-UM GSCs. Collectively, our findings provide a framework and rationale to further explore TUSC3-mediated epigenetic reprogramming strategies that could enhance TMZ sensitivity and outcomes in GBM. Mechanistic and translational evidence gained from such studies could contribute towards optimal design of impactful trials for MGMT-UM GBMs that currently do not have good treatment options.

This decreased MGMT mRNA expression was observed to have an inverse relationship with MGMT methylation levels. In this study, we found that the MGMT methylation level could potentially serve as a valuable prognostic indicator for the transition from ASC-US/LSIL to cervical cancer.

The 64 TMZ efficacy-related CpGs and in particular the 10-CpG risk signature may serve as promising predictive biomarker candidates for guiding optimal usage of TMZ in G-CIMP-/unMGMT GBMs.

MGMT promoter methylation is a positive factor for the prognosis of Glioblastoma (GBM), which can prolong overall survival and progression-free survival, reduce the resistance of tumor cells to temozolomide treatment, and improve the prognosis...Further studies exploring new methods targeting MGMT with better curative effect and less toxicity are advocated. We anticipate that these developments will be progressive and sufficiently used for clinical application.

Targeting MGMT via temozolomide, a DNA alkylating drug, and HR via Olaparib, a PARP1 inhibitor, caused synthetic lethality in human and murine AML samples expressing GFI1 -36N (3-fold, p<0.01), whereas the effects were insignificant in non-malignant GFI1 -36S or GFI1 -36N cells. GFI1 -36N impedes DNA repair in AML cells, opening a novel approach to treat AML on a personalized basis by targeting DNA repair. The observed findings are currently being validated in independent patient cohorts in cooperation with other groups.

P2, N=102, Active, not recruiting, IFOM ETS - The AIRC Institute of Molecular Oncology | Recruiting --> Active, not recruiting | Trial completion date: Dec 2023 --> Dec 2024 | Trial primary completion date: Sep 2023 --> Jun 2024

The results support the clinical benefit demonstrated for concomitant TTFields with TMZ plus CCNU, showing that the efficacy of TMZ and CCNU may be enhanced by TTFields, with synergism seen for the latter case in cells not expressing MGMT. The BRCAness state induced by TTFields rationalizes this, as in the absence of MGMT DNA damage induced by CCNU requires the FA-BRCA pathway for repair.

Targeting MGMT via temozolomide, a DNA alkylating drug, and HR via olaparib, a PARP1 inhibitor, caused synthetic lethality in human and murine AML samples expressing GFI1-36N, whereas the effects were insignificant in non-malignant GFI1-36S or GFI1-36N cells. This suggests that reduced MGMT expression leaves GFI1-36N leukemic cells particularly vulnerable to DNA damage initiating chemotherapeutics. Our data provide critical insights into novel options to treat AML patients carrying the GFI1-36N variant.

The reduction of MGMT expression levels reversed TMZ resistance in TMZ-resistant glioblastoma cell lines resulting in TMZ induced dose-dependent cell death rates. In conclusion, we demonstrate targeted RNA-guided methylation of the MGMT promoter as a promising tool to overcome chemoresistance and improve the cytotoxic effect of TMZ in glioblastoma.