# MZT2B promotes malignant phenotypes in NSCLC cells by enhancing mitochondrial function and COX5B expression

## TL;DR

This study shows that MZT2B promotes lung cancer growth by improving mitochondrial function and increasing COX5B levels, making it a potential new target for treatment.

## Contribution

MZT2B is identified as a novel oncogenic driver in NSCLC that regulates mitochondrial function and COX5B expression.

## Key findings

- MZT2B is significantly upregulated in NSCLC and linked to poor patient outcomes.
- MZT2B depletion reduces cancer cell viability and mitochondrial function.
- COX5B is a key downstream target of MZT2B in NSCLC progression.

## Abstract

Non-small cell lung cancer (NSCLC) remains a leading cause of cancer-related mortality, necessitating the identification of novel therapeutic targets. Here, we identify mitotic spindle organizing protein 2B (MZT2B) as a critical oncogenic driver and potential therapeutic vulnerability in NSCLC. TCGA analysis revealed significant MZT2B upregulation in NSCLC tissues, correlating with adverse clinicopathological features and poor prognosis of patients. Single-cell RNA sequencing analysis confirmed predominant MZT2B enrichment within malignant epithelial cells, particularly in proliferating carcinoma subsets, across primary tumors and metastatic sites (brain, lymph node, pleural effusions). Functional enrichment analyses highlighted MZT2B’s association with pathways critical for cellular respiration and mitochondrial ATP synthesis, coupled electron transport. Experimental validation in human NSCLC clinical specimens and various cell types further confirmed consistent MZT2B overexpression. Genetic silencing (via shRNA) or CRISPR/Cas9-mediated knockout of MZT2B in various NSCLC cell types significantly impeded cell viability, proliferation, migration, and invasion, inducing G1-S phase cell cycle arrest, and activating the intrinsic apoptotic pathway. Conversely, MZT2B overexpression promoted aggressive malignant phenotypes of NSCLC cells. Further investigation demonstrated MZT2B’s criticality for mitochondrial respiration and overall function, and its silencing or knockout inhibited oxygen consumption rates, ATP production, mitochondrial membrane potential, and cellular redox homeostasis (ROS, GSH/GSSG ratio). Integrated bioinformatic and experimental approaches identified cytochrome c oxidase subunit 5B (COX5B) as a significant downstream effector regulated by MZT2B in NSCLC cells. Restoring COX5B expression or increasing glucose concentration attenuated MZT2B depletion-induced anti-NSCLC cell effects. In vivo studies using subcutaneous xenograft models confirmed that MZT2B knockdown markedly impaired NSCLC tumor growth, reduced proliferation, increased apoptosis, downregulated COX5B expression and diminished mitochondrial function. Collectively, these findings establish MZT2B as a consistently upregulated gene in NSCLC correlating with adverse clinicopathological features and poor prognosis. MZT2B critically regulates mitochondrial function and promotes NSCLC progression, at least partially, through promoting COX5B expression.