Department of Otorhinolaryngology, Head and Neck Surgery, Medical University of Innsbruck, Innsbruck, Austria.
Department of Therapeutic Radiology and Oncology, Medical University of Innsbruck, Innsbruck, Austria.
Sci Rep. 2022 Aug 2;12(1):13255. doi: 10.1038/s41598-022-16829-5.
Mitochondrial dysfunction promotes cancer aggressiveness, metastasis, and resistance to therapy. Similar traits are associated with epithelial mesenchymal transition (EMT). We questioned whether mitochondrial dysfunction induces EMT in head and neck cancer (HNC) cell lines. We induced mitochondrial dysfunction in four HNC cell lines with carbonyl cyanide-4(trifluoromethoxy)phenylhydrazone (FCCP), a mitochondrial electron transport chain uncoupling agent, and oligomycin, a mitochondrial ATP synthase inhibitor. Extracellular flux analyses and expression of the cystine/glutamate antiporter system xc (xCT) served to confirm mitochondrial dysfunction. Expression of the EMT-related transcription factor SNAI2, the mesenchymal marker vimentin and vimentin/cytokeratin double positivity served to detect EMT. In addition, holotomographic microscopy was used to search for morphological features of EMT. Extracellular flux analysis and xCT expression confirmed that FCCP/oligomycin induced mitochondrial dysfunction in all cell lines. Across the four cell lines, mitochondrial dysfunction resulted in an increase in relative SNAI2 expression from 8.5 ± 0.8 to 12.0 ± 1.1 (mean ± SEM; p = 0.007). This effect was predominantly caused by the CAL 27 cell line (increase from 2.2 ± 0.4 to 5.5 ± 1.0; p < 0.001). Similarly, only in CAL 27 cells vimentin expression increased from 2.2 ± 0.5 × 10 to 33.2 ± 10.2 × 10 (p = 0.002) and vimentin/cytokeratin double positive cells increased from 34.7 ± 5.1 to 67.5 ± 9.8% (p = 0.003), while the other 3 cell lines did not respond with EMT (all p > 0.1). Across all cell lines, FCCP/oligomycin had no effect on EMT characteristics in holotomographic microscopy. Mitochondrial dysfunction induced EMT in 1 of 4 HNC cell lines. Given the heterogeneity of HNC, mitochondrial dysfunction may be sporadically induced by EMT, but EMT does not explain the tumor promoting effects of mitochondrial dysfunction in general.
线粒体功能障碍促进癌症侵袭性、转移和对治疗的耐药性。类似的特征与上皮间质转化 (EMT) 有关。我们质疑线粒体功能障碍是否会诱导头颈部癌症 (HNC) 细胞系发生 EMT。我们使用羰基氰化物-4(三氟甲氧基)苯腙 (FCCP)，一种线粒体电子传递链解偶联剂，和寡霉素，一种线粒体 ATP 合酶抑制剂，在四种 HNC 细胞系中诱导线粒体功能障碍。细胞外通量分析和胱氨酸/谷氨酸反向转运蛋白系统 xc (xCT) 的表达用于确认线粒体功能障碍。上皮间质转化相关转录因子 SNAI2、间充质标志物波形蛋白和波形蛋白/细胞角蛋白双阳性的表达用于检测 EMT。此外，全断层显微镜用于寻找 EMT 的形态学特征。细胞外通量分析和 xCT 表达证实，FCCP/寡霉素在所有细胞系中均诱导线粒体功能障碍。在这四种细胞系中，线粒体功能障碍导致相对 SNAI2 表达从 8.5±0.8 增加到 12.0±1.1（平均值±SEM；p=0.007）。这种作用主要是由 CAL 27 细胞系引起的（从 2.2±0.4 增加到 5.5±1.0；p<0.001）。同样，只有在 CAL 27 细胞中，波形蛋白表达从 2.2±0.5×10 增加到 33.2±10.2×10（p=0.002），波形蛋白/细胞角蛋白双阳性细胞从 34.7±5.1%增加到 67.5±9.8%（p=0.003），而其他 3 种细胞系没有发生 EMT（均 p>0.1）。在所有细胞系中，FCCP/寡霉素对全断层显微镜中的 EMT 特征没有影响。线粒体功能障碍在 4 种 HNC 细胞系中的 1 种中诱导 EMT。鉴于 HNC 的异质性，线粒体功能障碍可能偶尔由 EMT 诱导，但 EMT 并不能解释线粒体功能障碍在总体上促进肿瘤的作用。
