Increased expression of FAT4 suppress metastasis of lung adenocarcinoma through regulating MAPK pathway and associated with immune cells infiltration

Development of a prognostic model for lung adenocarcinoma polarity-related genes and analysis of immune landscape

Despite the progress made in the management of lung adenocarcinoma (LUAD), the overall prognosis for LUAD individuals remains suboptimal. While the role of cell polarity in tumor invasion and metastasis is well established, its prognostic significance in LUAD is still unknown. Differential analysis was performed on the Cancer Genome Atlas (TCGA)-LUAD and normal lung tissue, and candidate genes were identified by intersecting differentially expressed genes with polarity-related genes (PRGs). A prognostic model was constructed using univariate and multivariate Cox regression and LASSO regression. To enhance the robustness of the analysis, an independent prognostic analysis was conducted by incorporating relevant clinical information. The accuracy and sensitivity of the model were validated using survival analysis and ROC curves. Finally, immune landscape, immune therapy, tumor mutation burden, and drug sensitivity analysis were carried out on high- and low-risk patients. Ten prognostic genes were screened to divide LUAD patients into different risk groups. Survival analysis, ROC curves, and univariate/multivariate Cox regression analyses collectively demonstrated the favorable predictive performance of the model, which could be an independent prognostic factor. The nomogram, in conjunction with the calibration curve, demonstrated the model's compelling predictive capacity in prognosticating the overall survival of LUAD individuals. Low-risk LUAD patients exhibited heightened levels of immune cell infiltration, immune scores, and immune checkpoint expression compared to high-risk individuals. So, they may have a greater likelihood of benefiting from immune therapy. The high-risk group demonstrated a remarkably higher tumor mutation burden (TMB) in contrast with the low-risk group. XAV-939, Fulvestrant, and SR16157 may have potential value in the clinical use of LUAD. We revealed the potential linkage between PRGs and LUAD prognosis, and the application of these prognostic factors in risk stratification and prognosis prediction of LUAD patients may be of great significance.

FAT4 activation inhibits epithelial-mesenchymal transition (EMT) by promoting autophagy in H2228/Cer cells

As a tumor suppressor in lung cancer, FAT atypical cadherin 4 (FAT4) has a critical role in epithelial-mesenchymal transition (EMT). However, the role of FAT4 in ceritinib-resistant anaplastic lymphoma kinase (ALK) positive non-small cell lung cancer (NSCLC) EMT has not been reported. It is necessary to discuss the role of FAT4 in this process and its potential mechanism of interaction. We found that the expression level of FAT4 was downregulated markedly in ceritinib-resistant NCI-H2228 (H2228/Cer) cells. Jujuboside A, a FAT4 activator, diminished EMT and metastasis of H2228/Cer cells. Importantly, autophagy inhibition inverted the inhibitory effect of FAT4 activation on EMT. Furthermore, we found the regulatory action of FAT4 on autophagy was related to proteasome 26S subunit ubiquitin receptor and non-ATPase 4 (PSMD4) and proteasome 20S subunit beta 4 (PSMB4), and the inhibitory effect of autophagy on EMT might be related to ROS/NF-κB/IκB-α and Wnt/β-catenin pathways. In conclusion, FAT4 activation can inhibit the process of EMT in H2228/Cer cells by promoting autophagy, which provides a potential target for ceritinib-resistant ALK positive NSCLC therapy.