MZT2A promotes NSCLC viability and invasion by increasing Akt phosphorylation via the MOZART2 domain

Dysregulation of Microtubule Nucleating Proteins in Cancer Cells

Simple Summary

The dysfunction of microtubule nucleation in cancer cells changes the overall cytoskeleton organization and cellular physiology. This review focuses on the dysregulation of the γ-tubulin ring complex (γ-TuRC) proteins that are essential for microtubule nucleation. Recent research on the high-resolution structure of γ-TuRC has brought new insight into the microtubule nucleation mechanism. We discuss the effect of γ-TuRC protein overexpression on cancer cell behavior and new drugs directed to γ-tubulin that may offer a viable alternative to microtubule-targeting agents currently used in cancer chemotherapy.

Abstract

In cells, microtubules typically nucleate from microtubule organizing centers, such as centrosomes. γ-Tubulin, which forms multiprotein complexes, is essential for nucleation. The γ-tubulin ring complex (γ-TuRC) is an efficient microtubule nucleator that requires additional centrosomal proteins for its activation and targeting. Evidence suggests that there is a dysfunction of centrosomal microtubule nucleation in cancer cells. Despite decades of molecular analysis of γ-TuRC and its interacting factors, the mechanisms of microtubule nucleation in normal and cancer cells remains obscure. Here, we review recent work on the high-resolution structure of γ-TuRC, which brings new insight into the mechanism of microtubule nucleation. We discuss the effects of γ-TuRC protein dysregulation on cancer cell behavior and new compounds targeting γ-tubulin. Drugs inhibiting γ-TuRC functions could represent an alternative to microtubule targeting agents in cancer chemotherapy.

Identification of Key Genes Related to CD8+ T-Cell Infiltration as Prognostic Biomarkers for Lung Adenocarcinoma

Background

CD8+ T cells are one of the central effector cells in the immune microenvironment. CD8+ T cells play a vital role in the development and progression of lung adenocarcinoma (LUAD). This study aimed to explore the key genes related to CD8+ T-cell infiltration in LUAD and to develop a novel prognosis model based on these genes.

Methods

With the use of the LUAD dataset from The Cancer Genome Atlas (TCGA), the differentially expressed genes (DEGs) were analyzed, and a co-expression network was constructed by weighted gene co-expression network analysis (WGCNA). Combined with the CIBERSORT algorithm, the gene module in WGCNA, which was the most significantly correlated with CD8+ T cells, was selected for the subsequent analyses. Key genes were then identified by co-expression network analysis, protein–protein interactions network analysis, and least absolute shrinkage and selection operator (Lasso)-penalized Cox regression analysis. A risk assessment model was built based on these key genes and then validated by the dataset from the Gene Expression Omnibus (GEO) database and multiple fluorescence in situ hybridization experiments of a tissue microarray.

Results

Five key genes (MZT2A, ALG3, ATIC, GPI, and GAPDH) related to prognosis and CD8+ T-cell infiltration were identified, and a risk assessment model was established based on them. We found that the risk score could well predict the prognosis of LUAD, and the risk score was negatively related to CD8+ T-cell infiltration and correlated with the advanced tumor stage. The results of the GEO database and tissue microarray were consistent with those of TCGA. Furthermore, the risk score was higher significantly in tumor tissues than in adjacent lung tissues and was correlated with the advanced tumor stage.

Conclusions

This study may provide a novel risk assessment model for prognosis prediction and a new perspective to explore the mechanism of tumor immune microenvironment related to CD8+ T-cell infiltration in LUAD.

Calponin 3 suppresses proliferation, migration and invasion of non-small cell lung cancer cells

Calponin 3 (CNN3) is known to serve a role in certain types of cancer, such as gastric cancer and colorectal cancer. The present study investigated the clinical significance of CNN3 in non-small cell lung cancer (NSCLC) by evaluating its expression profile and relationship with disease prognosis using the Gene Expression Omnibus repository, Gene Expression Profiling Interactive Analysis 2 (GEPIA2) and Kaplan-Meier plotter analysis. CNN3 mRNA expression was measured using reverse transcription-quantitative PCR, while the protein expression level was measured using western blot analysis. Cell proliferation, cell cycle and apoptosis, and migration and invasion were analyzed using MTS assay, flow cytometry and Transwell assays, respectively. These results revealed that CNN3 mRNA expression was downregulated in NSCLC tissues compared with that in normal tissues. Additionally, CNN3 expression had a high diagnostic value based on the GSE2514 dataset and the data from The Cancer Genome Atlas and the Genotype Tissue Expression database, whereas it had a low diagnostic value based on the GSE10072 dataset. Furthermore, CNN3 expression was associated with survival in patients with lung adenocarcinoma (LUAD), whereas it was not associated with survival in patients with lung squamous cell carcinoma (LUSC) according to the Kaplan-Meier plotter results. According to the data from GEPIA2, and the GSE72094, GSE41271 and GSE31210 datasets, CNN3 expression was not associated with the prognosis of patients with LUAD and LUSC. The mRNA and protein expression levels of CNN3 were lower in two NSCLC cell lines (A549 and SK-MES-1) than in a human bronchial epithelial cell line (BEAS-2B). CNN3 overexpression suppressed cell proliferation, migration and invasion, induced G₁-phase arrest, promoted apoptosis and suppressed PI3K/AKT signaling pathway activation in the NSCLC cell lines, whereas CNN3 overexpression had no effect on cell morphology. In conclusion, CNN3 suppressed the proliferation and metastasis of NSCLC cells by downregulating the PI3K/AKT signaling pathway, making it a potential therapeutic target in this disease.

MZT2A promotes NSCLC viability and invasion by increasing Akt phosphorylation via the MOZART2 domain

Mitotic spindle organizing protein 2A (MZT2A) is localized at the centrosome and regulates microtubule nucleation activity in cells. This study assessed the role of MZT2A in non-small-cell lung cancer (NSCLC). Differential MZT2A expression was bioinformatically assessed using TCGA database, the GEPIA database, and Kaplan-Meier survival data to determine the association between MZT2A expression and NSCLC prognosis. Furthermore, NSCLC tissue specimens were evaluated by immunohistochemistry. MZT2A was overexpressed or knocked down in NSCLC cells using cDNA and siRNA, respectively. The cells were subjected to various assays and treated with the selective Akt inhibitor LY294002 or co-transfected with galectin-3-binding protein (LGALS3BP) siRNA. MZT2A mRNA and protein levels were upregulated in NSCLC lesions and MTZ2A expression was associated with poor NSCLC prognosis. MZT2A protein was also highly expressed in NSCLC cells compared with the expression in normal bronchial cells. MZT2A expression promoted NSCLC cell viability and invasion, whereas MTZ2A siRNA had the opposite effect on NSCLC cells in vitro. At the protein level, MZT2A induced Akt phosphorylation, promoting NSCLC proliferation and invasion (but the selective Akt inhibitor blocked these effects) through upregulation of LGALS3BP via the MTZ2A MOZART2 domain, whereas LGALS3BP siRNA suppressed MTZ2A activity in NSCLC cells. The limited in vivo experiments confirmed the in vitro data. In conclusion, MZT2A exhibits oncogenic activity by activating LGALS3BP and Akt in NSCLC. Future studies will assess MTZ2A as a biomarker to predict NSCLC prognosis or as a target in the control of NSCLC progression.