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The main event in the progression of pulmonary fibrosis is the appearance of myofibroblasts. Recent evidence supports pericytes as a major source of myofibroblasts. TGFβ/Smad2/3 and PDGF/Erk signaling pathways are important for regulating pericyte activation. Previous studies have demonstrated that PDGFβR and TGFβR are modified by core fucosylation (CF) catalyzed by α-1,6-fucosyltransferase (FUT8). The aim of this study was to compare the effect of inhibiting CF versus the PDGFβR and TGFβR signaling pathways on pericyte activation and lung fibrosis. FUT8shRNA was used to knock down FUT8-mediated CF both in vivo and in isolated lung pericytes. The small molecule receptor antagonists, ST1571 (imatinib) and LY2109761, were used to block the PDGFβ/pErk and TGFβ/pSmad2/3 signaling pathways, respectively. Pericyte detachment and myofibroblastic transformation were assessed by immunofluorescence and Western blot. Histochemical and immunohistochemical staining were used to evaluate the effect of the intervention on pulmonary fibrosis. Our findings demonstrate that FUT8shRNA significantly blocked pericyte activation and the progression of pulmonary fibrosis, achieving intervention effects superior to the small molecule inhibitors. The PDGFβ and TGFβ pathways were simultaneously affected by the CF blockade. FUT8 expression was upregulated with the transformation of pericytes into myofibroblasts, and silencing FUT8 expression inhibited this transformation. In addition, there is a causal relationship between CF modification catalyzed by FUT8 and pulmonary fibrosis. Our findings suggest that FUT8 may be a novel therapeutic target for pulmonary fibrosis.

Lung cancer is one of the most common causes of morbidity and mortality among malignant tumors worldwide. The poor prognosis of patients with lung adenocarcinomas is primarily due to its strong ability to invade and metastasize. Recent research has indicated that RNA-binding protein 10 (RBM10) is mutated in lung adenocarcinoma, and is closely associated with tumor proliferation and apoptosis; however, the precise role of RBM10 in lung adenocarcinoma remains unclear. Our preliminary experiments (unpublished data) revealed that RBM10 expression was upregulated in lung adenocarcinoma cell lines and tissues. In this study, we first detected the protein expression level of RBM10 in lung adenocarcinoma cells and tissues, and we then examined the effects of RBM10 overexpression and downregulation (via small interfering RNA) on the proliferation and apoptosis of stable lung adenocarcinoma cells, along with its possible mechanisms of action. We also used clinical samples of lung adenocarcinomas to verify our results. We found that RBM10 protein was overexpressed in lung adenocarcinoma cells and tissues, and it reduced p53 expression (as detected by immunofluorescence assay and western blot analysis) in A549 cells and inhibited apoptosis (as shown by flow cytometric assay). RBM10 also promoted cell growth and proliferation in vitro and increased cell migration in a cell wound scratch assay. Furthermore, we found that RBM10 activated key proliferative signaling pathways [such as the epidermal growth factor receptor (EGFR), mitogen-activated protein kinase (MAPK) and phosphoinositide 3-kinase (PI3K)-AKT pathways] and inhibited apoptotic pathways. In addition, we demonstrated that a high expression of RBM10 protein in patient tissue samples was associated with a shorter overall survival time and a poor prognosis. On the whole, the findings of this study indicate that RBM10 may function as an oncogene in lung cancer, and may thus prove to be a novel therapeutic target for the prophylaxis and treatment of lung adenocarcinomas.

Background The epidermal growth factor receptor (EGFR) is closely implicated in cancer, and sequencing analyses have revealed a high mutation rate of EGFR in lung cancer. Recent advances have provided novel insights into the endocytic regulation of wild-type EGFR, but that of mutated EGFR remains elusive. In the present study, we aim to investigate the endocytic degradation of a frequently occurred exon 19-deleted mutant in lung cancer. Methods The EGF-induced endocytic degradation of EGFR was examined in a panel of lung cancer cells using immunoblotting. The subcellular distribution of internalized EGFR was investigated using immunofluorescence and confocal microscopy. The effects of dynamin were assessed using its small molecule inhibitors, while the influence of RTN3 was tested using shRNA-mediated knockdown. Finally the ubiquitylation status of EGFR mutant was studied using immunoprecipitation under steady state and tyrosine kinase inhibitor-treated conditions. Results EGF induced various rates of EGFR endocytic degradation in lung cancer cells. Interestingly, the exon 19 deletion mutant is constantly internalized and sorted to lysosome for degradation, and this process is independent of dynamin activity. EGF stimulation and HSP90 inhibition further enhance the endocytic degradation of the exon 19 deletion mutant, in a dynamin activity-dependent and -independent manner, respectively. Albeit with different modes of internalization, the uptake of the exon 19-deleted EGFR is mediated through receptor ubiquitylation. Conclusions The internalized EGFR mutant is constantly routed through endosome to lysosome for degradation. The endocytosis of EGFR mutant occurs through both dynamin activity-dependent and -independent mechanisms. Our findings gain novel insights into the endocytic regulation of mutated EGFR and may have potential clinical implications.

Lung cancer is a leading cause of death worldwide, with mutations in EGFR frequently detected that render this receptor tyrosine kinase constantly active. Targeted therapy against EGFR has proved effective in lung cancer treatment, but secondary mutations in EGFR frequently cause drug resistance. In the efforts made to investigate alternative ways to inhibit mutant EGFR, we observed that the dynamin inhibitor dynasore effectively suppressed the exon 19-deleted mutant of EGFR. This agent inhibited cell proliferation, colony formation, cell migration, and cell cycle progression of HCC827 and H1650 cells driven by the exon 19-deleted EGFR mutant. From a mechanistic point of view, dynasore suppressed the activation of AKT and MEK in HCC827 and H1650 cells. However, dynasore failed to alter the subcellular distribution of EGFR, and another dynamin inhibitor, dyngo-4a, did not phenocopy the effects of dynasore, suggesting a dynamin activity-independent effect of dynasore. Finally, we show that dynasore induced the potent ubiquitylation of the exon 19-deleted mutant of EGFR. Our observations will shed light on the development of alternative therapeutic strategies that target mutant EGFR in lung cancer.

BPTF, a subunit of NURF, is well known to be involved in the development of eukaryotic cell, but little is known about its roles in cancers, especially in non-small-cell lung cancer (NSCLC). Here we showed that BPTF was specifically overexpressed in NSCLC cell lines and lung adenocarcinoma tissues. Knockdown of BPTF by siRNA significantly inhibited cell proliferation, induced cell apoptosis and arrested cell cycle progress from G1 to S phase. We also found that BPTF knockdown downregulated the expression of the phosphorylated Erk1/2, PI3K and Akt proteins and induced the cleavage of caspase-8, caspase-7 and PARP proteins, thereby inhibiting the MAPK and PI3K/AKT signaling and activating apoptotic pathway. BPTF knockdown by siRNA also upregulated the cell cycle inhibitors such as p21 and p18 but inhibited the expression of cyclin D, phospho-Rb and phospho-cdc2 in lung cancer cells. Moreover, BPTF knockdown by its specific shRNA inhibited lung cancer growth in vivo in the xenografts of A549 cells accompanied by the suppression of VEGF, p-Erk and p-Akt expression. Immunohistochemical assay for tumor tissue microarrays of lung tumor tissues showed that BPTF overexpression predicted a poor prognosis in the patients with lung adenocarcinomas. Therefore, our data indicate that BPTF plays an essential role in cell growth and survival by targeting multiply signaling pathways in human lung cancers.