Qsox1, or quiescin sulfhydryl oxidase 1, is an enzyme that oxidizes thiols during protein folding, reducing molecular oxygen to hydrogen peroxide [7]. It is involved in multiple biological functions, such as disulfide bond formation in proteins [4,7].

In cancer-related research, knockdown of Qsox1 has been shown to suppress tumor growth and invasion in vitro and in vivo [4]. For example, in EGFR-mutant non-small-cell lung cancer, aberrant m5C hypermethylation mediates intrinsic resistance to gefitinib through the NSUN2/YBX1/QSOX1 axis. NSUN2 methylates the QSOX1 coding sequence region, enhancing QSOX1 translation [1]. In esophageal cancer, Qsox1 facilitates dormant cancer stem cells to evade immune elimination via PD-L1 upregulation and CD8 T cell exclusion, and blocking Qsox1 can help eradicate residual dormant cancer stem cells [2]. In preeclampsia, hypoxia-induced upregulation of Qsox1 increases apoptosis in placentae by elevating intracellular hydrogen peroxide levels [5]. In hepatocellular carcinoma, Qsox1 promotes sorafenib-induced ferroptosis by inhibiting NRF2 activation and drives EGFR endosomal trafficking [6]. In colorectal cancer, N6-methyladenosine-modified circular RNA QSOX1 promotes resistance to anti-CTLA-4 therapy through induction of intratumoral regulatory T cells [8].

In summary, Qsox1 plays crucial roles in various biological processes, especially in cancer development and drug resistance. Loss-of-function studies, like knockdown experiments, have revealed its significance in these disease conditions, providing potential targets for therapeutic strategies. Additionally, in non-cancer related research, Qsox1 knockout mice have impaired mucus barrier function in the gut due to sialylation defects, indicating its importance in maintaining mucosal function [3].