MGMT overexpression

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.

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

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.

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.

Our study provides the first evidence that quercetin may induce apoptosis in MGMTGBM cells via dual inhibition of the Wnt3a/β-Catenin pathway and the Akt/NF-κB signaling pathway. These findings suggest that quercetin could be a novel agent for improving GBM treatment, especially in TMZ-resistant GBM with high MGMT expression.

Down-regulation of Wnt antagonist secreted frizzled-related protein 4 (sFRP4) in GBM and GSCs, indicating activation of the Wnt/β-catenin pathway, which could be involved in the conversion of iPSCs to CSCs. From future perspectives, our study will help in the creation of a rapid cell-based platform for understanding the complexity of GBM.

Reactive oxygen species-mediated DNA damage is at least partially involved. Combinational administration of NCT503 and TMZ may represent a novel and promising treatment strategy to enhance TMZ efficacy in patients with MGMT-high glioblastoma.

COL6A2 high-expression is an indicator for adverse glioma prognosis, and is correlated with TMZ-resistant and immune response. Meanwhile, it may be a prospective biomarker for treatment.

Those mechanisms must be evaluated to get a better understanding of the origin of the resistance. These data may support the development of new treatment strategies.

Mannose inhibited MGMT to enhance sensitivity of glioma cells to TMZ, with Wnt/β-catenin pathway involvement. Our data suggested that mannose could be an innovative agent to improve glioma treatment, particularly in TMZ-resistant glioma with high MGMT.

Our finding indicated that MGMT upregulation is induced via its DNA promoter hypomethylation. The highly expressed MGMT prevents the NOCs-induced cell malignant transformation and tumorigenesis, which suggests a potential novel approach for chemical carcinogenesis intervention by regulating aberrant epigenetic mechanisms.

The intracranial GBM mouse model also demonstrated that the synergy between PP and TMZ could be achieved through down-regulating β-catenin and MGMT, which prolonged the survival time of tumor-bearing mice. Taken together, our data suggest that PP may serve as the prospect medicine to improve the chemotherapeutic effect on GBM, especially for chemoresistant to TMZ induced by MGMT overexpression.

Moreover, intracellular levels of reactive oxygen species were elevated especially when NCT503 and TMZ treatments were combined, and the synergistic effects could be partially negated by NAC, a classic scavenger of reactive oxygen species. Taken together, these results suggest that NCT503 may be a promising agent for augmenting TMZ efficacy in the treatment of GBM, especially in TMZ-resistant GBMs with high expression of MGMT.

Here, we show that autophagy-deficient liver cancer cells exhibit increased DNA damage caused by the chemotherapeutic agent epirubicin...In the absence of autophagy, the chemosensitivity of liver cancer cells was increased, but this was reversed by MGMT overexpression, indicating that autophagy mediates resistance to chemotherapy in liver cancer cells via MGMT. These findings demonstrate a direct link between autophagy, MGMT, and DNA damage repair in liver cancer cells, and show that MGMT not only regulates chemosensitivity to alkylating agents, but may also be involved in other DNA damage repair processes in autophagy-deficient cells.

We conclude that after initial efficacy of ALK treatment, a pause followed by ALK rechallenge might be appropriate to prolong tumor control, improve quality of life and limit long-term adverse events. Increased MGMT expression under ALK might explain low efficacy of ALK rechallenge.

Overexpression of MYC and overexpression of MGMT were prognostic markers associated with unfavorable clinical outcomes in PCNSL.