FBXW7-mediated ERK3 degradation regulates the proliferation of lung cancer cells

Extracellular signal-regulated kinase 3 (ERK3) is an atypical member of the mitogen-activated protein kinase (MAPK) family, members of which play essential roles in diverse cellular processes during carcinogenesis, including cell proliferation, differentiation, migration, and invasion. Unlike other MAPKs, ERK3 is an unstable protein with a short half-life. Although deubiquitination of ERK3 has been suggested to regulate the activity, its ubiquitination has not been described in the literature. Here, we report that FBXW7 (F-box and WD repeat domain-containing 7) acts as a ubiquitination E3 ligase for ERK3. Mammalian two-hybrid assay and immunoprecipitation results demonstrated that ERK3 is a novel binding partner of FBXW7. Furthermore, complex formation between ERK3 and the S-phase kinase-associated protein 1 (SKP1)-cullin 1-F-box protein (SCF) E3 ligase resulted in the destabilization of ERK3 via a ubiquitination-mediated proteasomal degradation pathway, and FBXW7 depletion restored ERK3 protein levels by inhibiting this ubiquitination. The interaction between ERK3 and FBXW7 was driven by binding between the C34D of ERK3, especially at Thr417 and Thr421, and the WD40 domain of FBXW7. A double mutant of ERK3 (Thr417 and Thr421 to alanine) abrogated FBXW7-mediated ubiquitination. Importantly, ERK3 knockdown inhibited the proliferation of lung cancer cells by regulating the G1/S-phase transition of the cell cycle. These results show that FBXW7-mediated ERK3 destabilization suppresses lung cancer cell proliferation in vitro.

Propofol Regulates the Proliferation and Migration of Lung Cancer Cells Through Atr Signaling Pathway

Aims: Here we aim to investigate the regulation of propofol on DNA damage caused by replication fork arrest in esophageal squamous cell carcinoma cells.Methods: A549 and NCI-H460 cells were treated with propofol and hydroxyurea (HU) in vitro. CCK-8 assay was used to examine cell proliferation. Transwell assay was employed to investigate cell migration and invasion abilities. Western blotting was carried out to study the activities of ATR signals. Laser confocal microscopy was utilized to study the formation of p-RPA32 foci.Results: Propofol treatment promoted the apoptosis and suppresses the proliferation, migration and invasion, possibly by increasing the sensitivity of A549 and NCI-H460 cells against DNA damage. Propofol treatment enhanced the sensitivity of A549 and NCI-H460 cells to damages caused by replication fork arrest, as well as the activity of ATR signaling pathway. Propofol regulated the sensitivity of A549 and NCI-H460 cells to DNA replication damage by affecting the level of H3K27me3.Conclusions: The present study demonstrates that propofol up-regulates the expression of H3K27me3 in lung cancer cells, promotes the recruitment of exonuclease MUS81 in stagnant replication fork, induces apoptosis caused by DNA damage, and thus inhibits the proliferation and metastasis of tumor cells.

Proteasome Inhibitor Immunotherapy for the Epithelial to Mesenchymal Transition: Assessing the A549 Lung Cancer Cell Microenvironment and the Role of M1, M2a and M2c ‘Hydrocortisone-Polarised’ Macrophages

Lung cancer is a leading cause of cancer-related deaths, primarily as a result of metastases. In this metastasis, the epithelial-to-mesenchymal transition (EMT) is essential. Interaction with the cancer cell microenvironment is primarily dependent on M1- and M2-polarized macrophage. In this study, we revealed the EMT-associated activity of M1, M2a and M2c macrophages in A549 lung cancer cells. We established a co-culture model of A549 lung cancer cells utilizing THP-1-derived M1/M2 polarised macrophages to explore the involvement of macrophages in the immune response, apoptosis, and EMT in lung cancer. Although multiple polarising agents are routinely used for M1 and M2 conversion, we assessed a new possible polarising agent, hydrocortisone. M1 increased A549 cell sensitivity to proteasome inhibitors and decreased A549 cell viability by inducing apoptosis. EMT was induced in the presence of M2c macrophages in A549 cells by the levels of vimentin, fibronectin, E-cadherin, NF-kB, CCL-17. We also revealed the antiproliferative effects of bortezomib and ixazomib on A549 cells in both 2D and 3D cultures. Our findings could help develop an immunotherapeutic strategy by shedding light on a previously undiscovered part of the EMT pathway. Furthermore, additional investigation may reveal that polarising tumour-associated macrophages to M1 and eliminating the M2a or particularly the M2c subtype are effective anti-cancer strategies.

Neurokinin-1 receptor promotes non-small cell lung cancer progression through transactivation of EGFR

Despite the great advances in target therapy, lung cancer remains the top cause of cancer-related death worldwide. G protein-coupled receptor neurokinin-1 (NK1R) is shown to play multiple roles in various cancers; however, the pathological roles and clinical implication in lung cancer are unclarified. Here we identified NK1R as a significantly upregulated GPCR in the transcriptome and tissue array of human lung cancer samples, associated with advanced clinical stages and poor prognosis. Notably, NK1R is co-expressed with epidermal growth factor receptor (EGFR) in NSCLC patients’ tissues and co-localized in the tumor cells. NK1R can crosstalk with EGFR by interacting with EGFR, transactivating EGFR phosphorylation and regulating the intracellular signaling of ERK1/2 and Akt. Activation of NK1R promotes the proliferation, colony formation, EMT, MMP2/14 expression, and migration of lung cancer cells. The inhibition of NK1R by selective antagonist aprepitant repressed cell proliferation and migration in vitro. Knockdown of NK1R significantly slowed down the tumor growth in nude mice. The sensitivity of lung cancer cells to gefitinib/osimertinib is highly increased in the presence of the selective NK1R antagonist aprepitant. Our data suggest that NK1R plays an important role in lung cancer development through EGFR signaling and the crosstalk between NK1R and EGFR may provide a potential therapeutic target for lung cancer treatment.