For patients exhibiting non-small-cell lung cancer (NSCLC) with activating epidermal growth factor receptor (EGFR) mutations, epidermal growth factor receptor tyrosine kinase inhibitors (EGFR-TKIs) are a first-line treatment. However, most patients who initially responded to EGFR-TKIs eventually developed acquired resistance, limiting the effectiveness of therapy. It has long been known that epithelial–mesenchymal transition (EMT) leads to acquired resistance to EGFR-TKIs in NSCLC. However, the mechanisms underlying the resistance dependent on EMT are unknown. This research aimed to reveal the effects of LMNA in the regulation of acquired resistance to erlotinib by EMT in NSCLC. The acquired erlotinib-resistant cells (HCC827/ER) were induced by gradual increase of concentrations of erlotinib in erlotinib-sensitive HCC827 cells. RNA sequencing and bioinformatics analysis were performed to uncover the involvement of LMNA in the EMT process that induced acquired resistance to erlotinib. The effect of LMNA on cell proliferation and migration was measured by clone-formation, wound-healing, and transwell assays, respectively. The EMT-related protein, nuclear shape and volume, and cytoskeleton changes were examined by immunofluorescence. Western blot was used to identify the underlying molecular mechanism of LMNA regulation of EMT. HCC827/ER cells with acquired resistance to erlotinib underwent EMT and exhibited lower LMNA expression compared to parental sensitive cells. LMNA negatively regulated the expression of EMT markers; HCC827/ER cells showed a significant up-regulation of mesenchymal markers, such as CDH2, SNAI2, VIM, ZEB1, and TWIST1. The overexpression of LMNA in HCC827/ER cells significantly inhibited EMT and cell proliferation, and this inhibitory effect of LMNA was enhanced in the presence of 2.5 μM erlotinib. Furthermore, a decrease in LMNA expression resulted in a higher nuclear deformability and cytoskeletal changes. In HCC827/ER cells, AKT, FGFR, ERK1/2, and c-fos phosphorylation levels were higher than those in HCC827 cells; Furthermore, overexpression of LMNA in HCC827/ER cells reduced the phosphorylation of AKT, ERK1/2, c-fos, and FGFR. In conclusion, our findings first demonstrated that downregulation of LMNA promotes acquired EGFR-TKI resistance in NSCLC with EGFR mutations by EMT. LMNA inhibits cell proliferation and migration of erlotinib-resistant cells via inhibition of the FGFR/MAPK/c-fos signaling pathway. These findings indicated LMNA as a driver of acquired resistance to erlotinib and provided important information about the development of resistance to erlotinib treatment in NSCLC patients with EGFR mutations.

Background: Head and neck squamous cell carcinoma (HNSCC) represents almost 95% of head and neck cancer cases and ranks as the sixth most prevalent malignant tumor globally. Several treatment strategies, such as surgery, radiation, and chemotherapy, are implemented to boost the outcomes for patients with HNSCC. However, the overall survival rate for patients with HNSCC has remained poor. MBP346 is a novel pyrazole pyrimidine compound that is cytotoxic to HNSCC cells. Therefore, this study aims to investigate its effect on HNSCC and to explore its possible molecular mechanism. Methods: Cell viability of HNSCC (Cal33 and Scc15) cells and normal NOK cells treated with MBP346 was determined by Methylthiazolyldiphenyl-tetrazolium bromide (MTT) assay. Colony formation assay and Edu assay were used to detect cell proliferation. Cell cycle and apoptosis were analyzed by flow cytometry. Western blot was used for detecting cell cycle-related and cell apoptotic-related proteins. Immunofluorescence assay was performed to analyze the effect of MBP346 on reactive oxygen species (ROS) and mitochondrial membrane potential (MMP). Results: MBP346 significantly inhibited the proliferation of Cal33 and Scc15 cells, with half inhibitory concentrations of 1.56 ± 0.13 μmol·L⁻¹ and 4.41 ± 0.28 μmol·L⁻¹, respectively. The cell cycle-related proteins CyclinD1, CyclinA2, and CDK2 were downregulated, and P21 was upregulated in Cal33 and Scc15 cells treated with MBP346, which blocked the cell cycle in the S phase. MBP346 induced cell apoptosis in Cal33 and Scc15 cells by inducing ROS production. In addition, the elevated ROS decreased MMP to accelerate apoptosis. N-acetylcysteine (NAC), an ROS inhibitor, suppressed MBP346-induced cell apoptosis. Conclusions: MBP346 may serve as a therapeutic agent in HNSCC by inducing cell death. It achieves this by halting cell proliferation through cell cycle arrest and enhancing apoptosis due to increased ROS, which results in mitochondrial dysfunction.