Changes in global DNA methylation and hydroxymethylation in oral mucosa according to tobacco smoke exposure

20 years since the approval of first EGFR-TKI, gefitinib: Insight and foresight

Epidermal growth factor receptor (EGFR) actively involves in modulation of various cancer progression related mechanisms including angiogenesis, differentiation and migration. Therefore, targeting EGFR has surfaced as a prominent approach for the treatment of several types of cancers, including non-small cell lung cancer (NSCLC), pancreatic cancer, glioblastoma. Various first, second and third generation of EGFR tyrosine kinase inhibitors (EGFR-TKIs) have demonstrated effectiveness as an anti-cancer therapeutics. However, rapid development of drug resistance and mutations still remains a major challenge for the EGFR-TKIs therapy. Overcoming from intrinsic and acquired resistance caused by EGFR mutations warrants the further exploration of alternative strategies and discovery of novel inhibitors. In this review, we delve into the breakthrough discoveries have been made in previous 20 years, and discuss the currently ongoing efforts aimed to circumvent the chemo-resistance. We also highlight the new challenges, limitations and future directions for the development of improved therapeutic approaches such as fourth-generation EGFR-TKIs, peptides, nanobodies, PROTACs etc.

Acquired resistance to EGFR-TKIs in NSCLC mediates epigenetic downregulation of MUC17 by facilitating NF-κB activity via UHRF1/DNMT1 complex

Treatment with epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors (TKIs) has brought significant benefits to non-small cell lung cancer (NSCLC) patients with EGFR mutations. However, most patients eventually develop acquired resistance after treatment. This study investigated the epigenetic effects of mucin 17 (MUC17) in acquired drug-resistant cells of EGFR-TKIs. We found that GR/OR (gefitinib/osimertinib-resistance) cells enhance genome-wide DNA hypermethylation, mainly in 5-UTR associated with multiple oncogenic pathways, in which GR/OR cells exerted a pro-oncogenic effect by downregulating mucin 17 (MUC17) expression in a dose- and time-dependent manner. Gefitinib/osimertinib acquired resistance mediated down-regulation of MUC17 by promoting DNMT1/UHRF1 complex-dependent promoter methylation, thereby activating NF-κB activity. MUC17 increased the generation of IκB-α and inhibit NF-κB activity by promoting the expression of MZF1. In vivo results also showed that DNMT1 inhibitor (5-Aza) in combination with gefitinib/osimertinib restored sensitivity to OR/GR cells. Acquired drug resistance of gefitinib/osimertinib promoted UHRF1/DNMT1 complex to inhibit the expression of MUC17. MUC17 in GR/OR cells may act as an epigenetic sensor for biomonitoring the resistance to EGFR-TKIs.

The hMeDIP-Seq identified INPP4A as a novel biomarker for eosinophilic chronic rhinosinusitis with nasal polyps

Background: Eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) is an endotype of chronic rhinosinusitis with nasal polyps characterized by more severe symptoms, a stronger association with asthma and a greater recurrence risk. It is unknown whether DNA hydroxymethylation could influence ECRSwNP. Methods: Hydroxymethylated DNA immunoprecipitation sequencing was carried out in three distinct groups (control, ECRSwNP and NECRSwNP). Additional qRT-PCR, immunohistochemistry and analysis of the receiver operating characteristic curve were performed. Results: Between ECRSwNP and NECRSwNP, 26 genes exhibited differential DNA hydroxymethylation. Consistent with their hydroxymethylation level, GNAL, INPP4A and IRF4 expression levels were significantly different between ECRSwNP and the other two groups. The receiver operating characteristic curve revealed that INPP4A mRNA has a high predictive accuracy for ECRSwNP. Conclusion: DNA hydroxymethylation regulates the expression of multiple genes in ECRSwNP. INPP4A mRNA was markedly decreased in ECRSwNP polyps and can predict ECRSwNP.