• Bioinformatic analysis uncovering the role of microRNAs in conferring resistance to temozolomide treatment in glioblastoma.
  • Mahsa Seydi,1 Fateme Saadat pour,2 Somayeh Zamani,3 Ehsan Arefian,4,*
    1. Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran
    2. Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran
    3. Department of Cellular and Molecular Biology, Faculty of Biological Sciences, North Tehran Branch, Islamic Azad University, Tehran, Iran
    4. Department of Microbiology, School of Biology, College of Science, University of Tehran, Tehran, Iran


  • Introduction: Glioblastoma multiforme (GBM) is a common primary brain tumor. This tumor is characterized by rapid growth and poor prognosis with a median survival of only 14 to 15 months, even with aggressive interventions. Temozolomide (TMZ), is the standard treatment for GBM, typically administered in conjunction with radiotherapy; however, its effectiveness is often limited. Resistance to TMZ is a critical obstacle in managing of GBM treatment and stems from various factors, including tumor heterogeneity, the protective blood-brain barrier, and specific genetic alterations such as MGMT promoter methylation status. The heterogeneity within the tumor allows for diverse cell populations, some of which may inherently resist chemotherapy. Moreover, mechanisms like the activation of DNA repair pathways further complicate treatment outcomes, enabling tumor cells to survive despite TMZ treatment. Consequently, there is an urgent need for innovative therapeutic strategies that can address these resistance mechanisms and enhance survival rates for patients with GBM.
  • Methods: we conducted a search for glioblastoma and temozolomide resistance Using the Geo DataSets within the NCBI database. We selected and analyzed studies GSE234762 ،GSE151680، GSE217366 ،GSE208773 ،GSE200031، GSE182220، GSE154337، GSE98126، GSE110130 ،GSE111231 ،GSE111247، GSE138942، GSE140441، GSE148740 ،GSE153907، GSE165624 through GEO2R analysis. We organized the genes based on log2 fold change (log2FC) and identified those with reduced expression in temozolomide-resistant samples, applying the criterion of log2FC ≤ -1. A study published at 2022 aimed at identifying potential cell-free microRNAs (cfmiRs) that differentiate between patients with primary glioblastoma (pGBM) and those with recurrent glioblastoma (rGBM) found that cfmiR-3180-3p and cfmiR-5739 could be useful for diagnosing both types of tumors through a minimally invasive blood assay .
  • Results: The overlap between the target genes of miR-3180-3P and miR-5739 that was extracted from the TargetScan database and the genes with increased expression in temozolomide-resistant samples revealed three key genes: TFAP2A, HRH4, and CACNG8. Genes TFAP2A, HRH4, and CACNG8 are targeted by miR-5739 with Total context++ score of -0.32, -0.31, and -0.22, in order, while miR-3180 targets these genes with Total context++ score of -0.35, -0.21, and -0.19, respectively. The log2 fold change levels of all three genes have demonstrated a decrease in expression in samples associated with temozolomide resistance across at least two Geodata sets.
  • Conclusion: In addition to the role of microRNAs in tumor biology, each of these genes plays a distinct role in tumor biology and potential therapeutic strategies. The downregulation of TFAP2A, HRH4, and CACNG8 genes plays a critical role in glioblastoma multiforme (GBM) progression. TFAP2A, a transcription factor, is essential for regulating cellular processes such as differentiation and proliferation. Its decreased expression in GBM correlates with increased tumor aggressiveness and poor prognosis, suggesting it acts as a tumor suppressor in this context. Similarly, HRH4, which encodes a histamine receptor involved in immune response regulation, also shows reduced expression in GBM. This downregulation may hinder the immune system's ability to recognize and combat tumor cells, facilitating unchecked tumor growth. CACNG8, part of the calcium channel family, is associated with critical signaling pathways that influence apoptosis and cell cycle regulation. Its decreased expression can disrupt these processes, further promoting tumor survival and resistance to therapies. The combined effect of reduced expression of these three genes contributes to the complex biology of GBM, enabling tumor progression and treatment resistance. Understanding the roles of TFAP2A, HRH4, and CACNG8 in GBM may provide insights into potential therapeutic targets. Targeting these genes could lead to novel strategies for overcoming resistance and improving patient outcomes in glioblastoma treatment. As a recommendation for further research, utilizing anti-miRs could allow us to examine the changes in expression levels of these three genes and their impact on resistance to temozolomide treatment.
  • Keywords: GBM, TMZ Resistance, miR