Cinnamophilin enhances temozolomide-induced cytotoxicity against malignant glioma: the roles of ROS and cell cycle arrest

Identification and validation of a novel prognostic signature based on mitochondria and oxidative stress related genes for glioblastoma

BACKGROUND

Mitochondria represent a major source of reactive oxygen species (ROS) in cells, and the direct increase in ROS content is the primary cause of oxidative stress, which plays an important role in tumor proliferation, invasion, angiogenesis, and treatment. However, the relationship between mitochondrial oxidative stress-related genes and glioblastoma (GBM) remains unclear. This study aimed to investigate the value of mitochondria and oxidative stress-related genes in the prognosis and therapeutic targets of GBM.

METHODS

We retrieved mitochondria and oxidative stress-related genes from several public databases. The LASSO regression and Cox analyses were utilized to build a risk model and the ROC curve was used to assess its performance. Then, we analyzed the correlation between the model and immunity and mutation. Furthermore, CCK8 and EdU assays were utilized to verify the proliferative capacity of GBM cells and flow cytometry was used to analyze apoptosis rates. Finally, the JC-1 assay and ATP levels were utilized to detect mitochondrial function, and the intracellular ROS levels were determined using MitoSOX and BODIPY 581/591 C11.

RESULTS

5 mitochondrial oxidative stress-related genes (CTSL, TXNRD2, NUDT1, STOX1, CYP2E1) were screened by differential expression analysis and Cox analysis and incorporated in a risk model which yielded a strong prediction accuracy (AUC value = 0.967). Furthermore, this model was strongly related to immune cell infiltration and mutation status and could identify potential targeted therapeutic drugs for GBM. Finally, we selected NUDT1 for further validation in vitro. The results showed that NUDT1 was elevated in GBM, and knockdown of NUDT1 inhibited the proliferation and induced apoptosis of GBM cells, while knockdown of NUDT1 damaged mitochondrial homeostasis and induced oxidative stress in GBM cells.

CONCLUSION

Our study was the first to propose a prognostic model of mitochondria and oxidative stress-related genes, which provided potential therapeutic strategies for GBM patients.

Activated TRPA1 plays a therapeutic role in TMZ resistance in glioblastoma by altering mitochondrial dynamics

Background

Glioblastoma (GBM) represents nearly one-half of primary brain tumors, and the median survival of patients with GBM is only 14.6 months. Surgery followed by radiation with concomitant temozolomide (TMZ) therapy is currently the standard of care. However, an increasing body of evidence suggests that GBM acquires resistance to TMZ, compromising the effect of the drug. Thus, further exploration into the mechanism underlying this resistance is urgently needed. Studies have demonstrated that TMZ resistance is associated with DNA damage, followed by altered reactive oxygen species (ROS) production in mitochondria. Studies have also showed that Ca2+-related transient receptor potential (TRP) channels participate in GBM cell proliferation and metastasis, but the detailed mechanism of their involvement remain to be studied. The present study demonstrates the role played by TRPA1 in TMZ resistance in GBM and elucidates the mechanism of resistance.

Methods

U251 and SHG-44 cells were analyzed in vitro. A CCK-8 assay was performed to verify the effect of TMZ toxicity on GBM cells. Intracellular ROS levels were detected by DCFH-DA assay. A MitoSOX Red assay was performed to determine the mitochondrial ROS levels. Intracellular Ca2+ levels in the cells were determined with a Fluo-4 AM calcium assay kit. Intracellular GSH levels were determined with GSH and GSSG Assay Kit. MGMT protein, Mitochondrial fission- and fusion-, apoptosis- and motility-related protein expression was detected by western blot assay. A recombinant lentiviral vector was used to infect human U251 cells to overexpress shRNA and generate TRPA1+/+ and negative control cells. All experiments were repeated.

Results

In the U251 and SHG-44 cells, TMZ induced a small increase in the apoptosis rate and intracellular and mitochondrial ROS levels. The expression of antioxidant genes and antioxidants in these cells was also increased by TMZ. However, pretreatment with a TRPA1 agonist significantly decreased the level of antioxidant gene and antioxidants expression and enhanced intracellular and mitochondrial ROS levels. Also TMZ induced the level of MGMT protein increased, and pretreatment with a TRPA1 agonist decreased the MGMT expression. Moreover, Ca2+ influx, mitochondrial damage and cell apoptosis were promoted, and the balance between mitochondrial fission and fusion protein expression was disrupted in these GBM cells. Pretreatment with a TRPA1 inhibitor slightly enhanced the level of antioxidant gene expression and reduced the apoptosis rate. TRPA1 gene overexpression in the U251 cells was similar to that after inhibitor intervention, confirming the aforementioned experimental results.

Conclusion

The present study proved that activating TRPA1 in glioma cells, which leads to mitochondrial damage and dysfunction and ultimately to apoptosis, may decrease the TMZ resistance of GBM cells.

Synergistic Effects of A Combined Treatment of Glioblastoma U251 Cells with An Anti-miR-10b-5p Molecule and An AntiCancer Agent Based on 1-(3',4',5'-Trimethoxyphenyl)-2-Aryl-1H-Imidazole Scaffold

(1) Background: In the development of new and more effective anticancer approaches, combined treatments appear of great interest. Combination therapy could be of importance in the management of glioblastoma (GBM), a lethal malignancy that accounts for 42% of cancer of the central nervous system, with a median survival of 15 months. This study aimed to verify the activity on a glioblastoma cancer cell line of one of the most active compounds of a novel series of tubulin polymerization inhibitors based on the 1-(3′,4′,5′-trimethoxyphenyl)-2-aryl-1H-imidazole scaffold, used in combination with a miRNA inhibitor molecule targeting the oncomiRNA miR-10b-5p. This microRNA was selected in consideration of the role of miR-10b-5p on the onset and progression of glioblastoma. (2) Methods: Apoptosis was analyzed by Annexin-V and Caspase 3/7 assays, efficacy of the anti-miR-10b-5p was assessed by determining the miR-10b-5p content by RT-qPCR. (3) Results: The results obtained show that a “combination therapy” performed by combining the use of an anti-miR-10b-5p and a 1-(3′,4′,5′-trimethoxyphenyl)-2-aryl-1H-imidazole derivative is an encouraging strategy to boost the efficacy of anticancer therapies and at the same time to reduce side effects.