目的·分析线粒体相关基因SFXN3（sideroflexin 3）在头颈部鳞状细胞癌（head and neck squamous cell carcinoma，HNSCC）中的表达及其对细胞增殖的影响。方法·从公共数据库获取与线粒体相关的基因和TCGA-HNSCC数据集，使用生物信息学方法筛选出目标基因SFXN3。使用UALCAN数据库分析SFXN3在HNSCC患者样本中的表达，并根据TCGA-HNSCC队列和GEO队列（GSE65858、GSE41613和GSE27020）对不同SFXN3表达水平的患者进行生存分析，使用TCGA-HNSCC队列和GEO队列（GSE40020、GSE210287）在治疗有应答和无应答的患者之间比较SFXN3表达水平差异。通过实时荧光定量PCR（quantitative real-time PCR，qRT-PCR）在收集的HNSCC癌和癌旁组织验证SFXN3的表达情况，并检测SFXN3在人正常口腔上皮细胞和HNSCC肿瘤细胞系中的表达水平。构建稳定敲低SFXN3的HNSCC细胞株，使用Incucyte活细胞成像分析系统和平板克隆形成实验观察SFXN3对HNSCC细胞增殖能力的影响。将稳定敲低SFXN3的细胞和对照组细胞的总RNA进行转录组测序，对敲低组相比对照组差异表达下调的基因进行通路富集分析。结果·SFXN3在HNSCC患者肿瘤组织中高表达（P=0.000），SFXN3高表达组患者预后较差（均P<0.05）；治疗无应答者SFXN3表达水平高于有应答者（P=0.008），提示不良预后。并且在收集的HNSCC肿瘤组织和HNSCC细胞系上验证了SFXN3的高表达（均P<0.05）。SFXN3的表达水平敲低后，HNSCC细胞的增殖能力下降，平板克隆形成数目减少（均P<0.05）。RNA测序显示，SFXN3敲低组的HNSCC细胞差异表达下调的基因在DNA复制、细胞周期、线粒体翻译、线粒体RNA代谢过程、线粒体基因表达等通路富集。结论·SFXN3在HNSCC中高表达，与患者预后负相关。HNSCC细胞敲低SFXN3后增殖能力和平板克隆形成能力受到抑制，可能通过影响线粒体功能发挥作用。

Objective ·To analyze the expression of mitochondrial related gene SFXN3 (sideroflexin 3) in head and neck squamous cell carcinoma (HNSCC) and its effect on cell proliferation. Methods ·Mitochondrial related genes and TCGA-HNSCC dataset were obtained from public databases to identify the target gene SFXN3 by using bioinformatic methods. The expression of SFXN3 in HNSCC patient samples was analysed by using the UALCAN database, and survival analyses of patients with different SFXN3 expression levels were performed according to TCGA-HNSCC cohort and GEO cohorts (GSE65858, GSE41613 and GSE27020). By using TCGA-HNSCC cohort and GEO cohorts (GSE40020, GSE210287), the differences in SFXN3 expression levels between therapeutic responders and non-responders were compared. Quantitative real-time PCR (qRT-PCR) was used to verify the expression of SFXN3 in the collected HNSCC tumor and para-tumor tissues, and the expression level of SFXN3 in human normal oral epithelial cells and HNSCC tumor cell lines was detected. With the construction of stable-SFXN3-knockdown HNSCC cell lines, the effect of SFXN3 on the proliferation ability of HNSCC cells was observed by using the Incucyte live-cell imaging analysis system and plate colony formation assay. Transcriptome sequencing was performed on the total RNA of stably-SFXN3-knockdown cells and control cells, and pathway enrichment analysis was performed on the genes with differentially down-regulated expression in knockdown group compared with control group. Results ·SFXN3 was highly expressed in tumor tissues of HNSCC patients (P=0.000), and the prognosis of patients in the SFXN3-high-expression group was poor (all P<0.05). The expression level of SFXN3 in the non-responders was higher than that in the responders (P=0.008), indicating an unfavorable prognosis. High expression of SFXN3 was verified in the collected HNSCC tumor tissues and HNSCC cell lines (all P<0.05). After the knockdown of SFXN3 expression, the proliferation ability of HNSCC cells decreased, and the number of plate clones decreased (all P<0.05). RNA sequencing showed that the differentially expressed down-regulated genes in HNSCC cells in the SFXN3-knockdown group were enriched in DNA replication, cell cycle, mitochondrial translation, mitochondrial RNA metabolic process and mitochondrial gene expression pathways. Conclusion ·SFXN3 is highly expressed in HNSCC and it has negative correlation with the prognosis of patients. The proliferation ability and plate colony formation ability are inhibited in SFXN3-knockdown HNSCC cells, and these may work by affecting mitochondria function.