Hypoxia-induced ROS promotes mitochondrial fission and cisplatin chemosensitivity via HIF-1α/Mff regulation in head and neck squamous cell carcinoma.

Chemotherapy based on cisplatin (CDDP) has been established as the treatment of choice for head and neck squamous cell carcinoma (HNSCC). Malignant tumors respond to microenvironmental alterations through a dynamic balance between mitochondrial fission and fusion. HNSCCs are known to exhibit hypoxic conditions, yet the respective effects and underlying mechanisms of hypoxia on chemosensitivity and mitochondrial dynamics remain to be resolved. The effect of hypoxia on the chemosensitivity of HNCC cells was determined by flow cytometry. Mitochondrial fission factor (Mff) expression was assessed by RT-PCR and Western blotting in hypoxic HNSCC cells, and further verified in primary CDDP-sensitive and CDDP-resistant HSNCC samples. The biological function of Mff was evaluated by loss of function and gain of function analyses, both in vitro and in vivo. We found that hypoxia promoted mitochondrial fission and CDDP sensitivity in HNSCC cells. Importantly, Mff was found to be correlated with chemosensitivity in primary clinical samples under hypoxic conditions. Hypoxia-inducible factor 1α (HIF-1α) was found to markedly increase Mff transcription and to directly bind to Mff. Hypoxia enhanced the release of reactive oxygen species (ROS) and upregulated the expression of Mff via HIF-1α in HNSCC cells. ROS depletion in HNSCC cells attenuated HIF-1α expression, Mff expression and mitochondrial fission. Moreover, Mff knockdown led to suppression of hypoxia-induced mitochondrial fission and to decreased CDDP chemosensitivity in vivo and in vitro. Our findings indicate that hypoxia-induced release of ROS can promote mitochondrial fission and CDDP chemosensitivity via HIF1α/Mff regulation in HNSCC cells, indicating that Mff may serve as a biomarker to predict neoadjuvant chemosensitivity in HNSCC patients and as a target for overcoming chemoresistance.

Wu K ，Mao YY ，Chen Q ，Zhang B ，Zhang S ，Wu HJ ，Li Y ... -  《-》

Hypoxia-induced SENP3 promotes chemosensitivity and mitochondrial fission via deSUMOylation of Drp1.

The study aimed to investigate the effect of the SUMOylation status of Drp1 on mitochondrial fission in CDDP-treated HNSCC cells cultured under hypoxic conditions. The effect of hypoxia on the chemosensitivity of HNCC cells was evaluated by flow cytometry and CCK-8 assays. The biological function of SUMO-specific peptidase 3 (SENP3) was evaluated by loss-of-function assays both in vitro and in vivo. SENP3-regulated deSUMOylation of Drp1 were performed with co-IP assays. SENP3 expression correlated with chemosensitivity in clinical HNSCC samples subjected to hypoxic conditions. Hypoxia-induced ROS increased HIF-1α/SENP3 expression and mitochondrial fission in CDDP-treated HNSCC cells, and these effects were reversed by NAC treatment. SENP3 knockdown reversed hypoxia-induced mitochondrial fission and inhibited HNSCC cell apoptosis, which decreased CDDP sensitivity. Furthermore, hypoxia-induced SENP3 deconjugated SUMO2 from Drp1. Our findings revealed that hypoxia-induced SENP3 facilitates CDDP sensitivity and mitochondrial fission via deSUMOylation of Drp1.

Mao Y ，Liu K ，Yang Y ，Liang Y ，Gong Z ，Wu K ... -  《-》

miR-483-5p determines mitochondrial fission and cisplatin sensitivity in tongue squamous cell carcinoma by targeting FIS1.

Fan S ，Chen WX ，Lv XB ，Tang QL ，Sun LJ ，Liu BD ，Zhong JL ，Lin ZY ，Wang YY ，Li QX ，Yu X ，Zhang HQ ，Li YL ，Wen B ，Zhang Z ，Chen WL ，Li JS ... -  《-》

Mitochondrial fission determines cisplatin sensitivity in tongue squamous cell carcinoma through the BRCA1-miR-593-5p-MFF axis.

Fan S ，Liu B ，Sun L ，Lv XB ，Lin Z ，Chen W ，Chen W ，Tang Q ，Wang Y ，Su Y ，Jin S ，Zhang D ，Zhong J ，Li Y ，Wen B ，Zhang Z ，Yang P ，Zhou B ，Liang Q ，Yu X ，Zhu Y ，Hu P ，Chu J ，Huang W ，Feng Y ，Peng H ，Huang Q ，Song E ，Li J ... -  《Oncotarget》

LncRNA UCA1 promotes proliferation and cisplatin resistance of oral squamous cell carcinoma by sunppressing miR-184 expression.

Chemotherapy resistance has become the main obstacle for the effective treatment of human cancers. Long non-coding RNA urothelial cancer associated 1 (UCA1) is generally regarded as an oncogene in some cancers. However, the function and molecular mechanism of UCA1 implicated in cisplatin (CDDP) chemoresistance of oral squamous cell carcinoma (OSCC) is still not fully established. UCA1 expression in tumor tissues and cells was tested by qRT-PCR. MTT, flow cytometry and caspase-3 activity analysis were explored to evaluate the CDDP sensitivity in OSCC cells. Western blot analysis was used to measure BCL2, Bax and SF1 protein expression. Luciferase reporter assay was conducted to investigate the molecular relationship between UCA1, miR-184, and SF1. Nude mice model was used to confirm the functional role of UCA1 in CDDP resistance in vivo. UCA1 expression was upregulated in OSCC tissues, cell lines, and CDDP resistant OSCC cells. Function analysis revealed that UCA1 facilitated proliferation, enhanced CDDP chemoresistance, and suppressed apoptosis in OSCC cells. Mechanisms investigation indicated that UCA1 could interact with miR-184 to repress its expression. Rescue experiments suggested that downregulation of miR-184 partly reversed the tumor suppression effect and CDDP chemosensitivity of UCA1 knockdown in CDDP-resistant OSCC cells. Moreover, UCA1 could perform as a miR-184 sponge to modulate SF1 expression. The OSCC nude mice model experiments demonstrated that depletion of UCA1 further boosted CDDP-mediated repression effect on tumor growth. UCA1 accelerated proliferation, increased CDDP chemoresistance and restrained apoptosis partly through modulating SF1 via sponging miR-184 in OSCC cells, suggesting that targeting UCA1 may be a potential therapeutic strategy for OSCC patients.

Fang Z ，Zhao J ，Xie W ，Sun Q ，Wang H ，Qiao B ... -  《Cancer Medicine》