BCAR1 plays critical roles in the formation and immunoevasion of invasive circulating tumor cells in lung adenocarcinoma.

Background: We investigated the roles of breast cancer anti-estrogen resistance 1 (BCAR1/p130Cas) in the formation and immunoevasion of invasive circulating tumor cells (CTCs) in lung adenocarcinoma (LUAD). Methods: Biomarkers of CTCs including BCAR1 and CD274, were evaluated by the CanPatrol method. Proteomics analysis of LUAD cells and exosomes after BCAR1 overexpression (BCAR1-OE) was performed by mass spectrometry. Cell functions and relevant signaling pathways were investigated after BCAR1 knockdown (BCAR1-KO) or BCAR1-OE in LUAD cells. Lastly, in vitro and in vivo experiments were performed to confirm the roles of BCAR1 in the formation and immunoevasion of CTCs. Results: High expression of BCAR1 by CTCs correlated with CD274 expression and epithelial-to-mesenchymal transition (EMT). RAC1, together with BCAR1, was found to play an important role in the carcinogenesis of LUAD. RAC1 functioned with BCAR1 to induce EMT and to enhance cell proliferation, colony formation, cell invasion and migration, and anoikis resistance in LUAD cells. BCAR1 up-regulated CD274 expression probably by shuttling the short isoform of BRD4 (BRD4-S) into the nucleus. CTCs, as well as tumor formation, were prohibited in nude mice xenografted with BCAR1-KO cells. The co-expression of BCAR1/RAC1 and BCAR1/CD274 was confirmed in LUAD. BCAR1 expression in LUAD is an indicator of poor prognosis, and it associates with immunoevasion. Conclusion: BCAR1, as a new target for the treatment of LUAD, plays roles in the formation and immunoevasion of invasive CTCs. The mechanism includes triggering EMT via RAC1 signaling and up-regulating CD274 expression by shuttling BRD4-S into the nucleus.

Circulating tumor cells with epithelial-mesenchymal transition markers as potential biomarkers for the diagnosis of lung cancer.

BACKGROUND: Circulating tumor cells (CTCs) can be clustered into three subtypes according to epithelial-mesenchymal transition (EMT) markers: CTCs with epithelial markers (E-CTCs), CTCs with mesenchymal markers (M-CTCs), and CTCs with both markers (E&M-CTCs). CTC detection has clinical implications in the diagnosis of lung cancer (LC). AIM: To clarify the diagnostic value of CTCs categorized by EMT markers in LC. METHODS: The study included 106 patients with lung adenocarcinoma, including 42 ground-glass opacities (GGO) and 64 solid lesions, who underwent surgery between July 2015 and December 2019. Eleven patients with benign tumors and seventeen healthy controls were included. CTCs in peripheral blood and associated EMT markers were detected preoperatively using the CanPatrolTM technique. The diagnostic power of CTCs for discriminating LC cases from controls was analyzed by the receiver operating characteristic (ROC) curve. The CytoploRare technique was used in 20 cases and 18 controls for validation, and Kappa values were calculated to evaluate consistency between techniques. RESULTS: Of the 106 LC cases, 94 (89.6%) had at least one CTC. CTCs were detectable in 35 (83.3%) of 42 GGO cases. Total CTCs and E&M-CTCs were significantly more frequent in LC cases than in benign or healthy controls. The proportion of M-CTCs plus E&M-CTCs increased gradually from healthy controls, to benign controls, to LC cases. The area under the ROC curve of total CTCs and E&M-CTCs was > 0.8 and > 10.75, respectively. The combined sensitivity of total-CTCs and E&M-CTCs was 85.85% for LC patients (80.95% for GGO patients) and the specificity was 78.57%. The Kappa value was 0.415, indicating relative consistency between CanPatrolTM and CytoploRare. CONCLUSION: CTC detection is valuable for distinguishing LC from controls, and particularly E&M-CTC detection warrants further study.

BCAR1 promotes proliferation and cell growth in lung adenocarcinoma via upregulation of POLR2A.

BACKGROUND: This study was designed to investigate the effects of a novel carcinogenetic molecule, p130cas (breast cancer antiestrogen resistance protein 1 or BCAR1) on proliferation and cell growth in lung adenocarcinoma. The study also aimed to identify the possible underlying signal networks of BCAR1. METHODS: First, we evaluated proliferation, cell colony formation, apoptosis, and cell cycle after BCAR1 was knocked out (KO) using CRISPR-Cas9 technology in H1975 and H1299 human lung adenocarcinoma cells. Subsequently, BCAR1 was upregulated in 293T cells and immunoprecipitation-mass spectrometry (IP-MS) was used with bioinformatics analysis to screen for potential networks of BCAR1 interacting proteins. Ultimately, we validated the correlated expressions of BCAR1 and a selected hub gene, RNA polymerase II subunit A (POLR2A), in 54 lung adenocarcinoma tissues, as well as in H1975 and H1299 cells. RESULTS: Cell proliferation of H1975 and H1299 was significantly inhibited following BCAR1-KO. Colony formation of H1975 cells was also significantly decreased following BCAR1-KO. IP-MS demonstrated 419 potential proteins that may interact with BCAR1. Among them, 68 genes were significantly positively correlated to BCAR1 expression, as verified by TCGA. Six hub genes were revealed by PPI String. High expression of POLR2A, MAPK3, MOV10, and XAB2 predicted poor prognosis in lung adenocarcinoma, as verified by the K-M plotter database. POLR2A and MAPK3 are involved in both catalytic activity and transferase activity. POLR2A and BCAR1 were significantly increased in lung cancer tissues as compared with matched normal tissues. High expression of POLR2A was significantly positively correlated to BCAR1 overexpression and predicted poor prognosis in 54 lung cancer cases. POLR2A expression was significantly decreased following BCAR1-KO in H1975 and H1299 cells. CONCLUSIONS: BCAR1 promotes proliferation and cell growth, probably via upregulation of POLR2A and subsequent enhancement of catalytic and transferase activities. However, additional robust studies are required to elucidate the mechanisms involved.