Instituto de Biotecnología, Centro de Investigación Biomédica, Universidad de Granada, Granada, Spain.
Departamento de Fisiología, Facultad de Medicina, Universidad de Granada, Granada, Spain.
Oxid Med Cell Longev. 2019 Feb 28;2019:7187128. doi: 10.1155/2019/7187128. eCollection 2019.
Head and neck cancer is the sixth leading cancer by incidence worldwide. Unfortunately, drug resistance and relapse are the principal limitations of clinical oncology for many patients, and the failure of conventional treatments is an extremely demoralizing experience. It is therefore crucial to find new therapeutic targets and drugs to enhance the cytotoxic effects of conventional treatments without potentiating or offsetting the adverse effects. Melatonin has oncostatic effects, although the mechanisms involved and doses required remain unclear. The purpose of this study is to determine the precise underlying mitochondrial mechanisms of melatonin, which increase the cytotoxicity of oncological treatments, and also to propose new melatonin treatments in order to alleviate and reverse radio- and chemoresistant processes. We analyzed the effects of melatonin on head and neck squamous cell carcinoma (HNSCC) cell lines (Cal-27 and SCC-9), which were treated with 0.1, 0.5, 1, and 1.5 mM melatonin combined with 8 Gy irradiation or 10 M cisplatin. Clonogenic and MTT assays, as well as autophagy and apoptosis, involving flow cytometry and western blot, were performed in order to determine the cytotoxic effects of the treatments. Mitochondrial function was evaluated by measuring mitochondrial respiration, mtDNA content (RT-PCR), and mitochondrial mass (NAO). ROS production, antioxidant enzyme activity, and GSH/GSSG levels were analyzed using a fluorometric method. We show that high concentrations of melatonin potentiate the cytotoxic effects of radiotherapy and CDDP in HNSCC, which are associated with increased mitochondrial function in these cells. In HNSCC, melatonin induces intracellular ROS, whose accumulation plays an upstream role in mitochondria-mediated apoptosis and autophagy. Our findings indicate that melatonin, at high concentrations, combined with cisplatin and radiotherapy to improve its effectiveness, is a potential adjuvant agent.
头颈部癌症是全球发病率第六位的癌症。不幸的是，耐药性和复发是许多患者临床肿瘤学的主要限制，常规治疗的失败是一种极其令人沮丧的经历。因此，寻找新的治疗靶点和药物以增强常规治疗的细胞毒性作用而不增强或抵消不良反应至关重要。褪黑素具有抗肿瘤作用，尽管涉及的机制和所需剂量尚不清楚。本研究的目的是确定褪黑素增加肿瘤治疗细胞毒性的确切潜在线粒体机制，并提出新的褪黑素治疗方法，以减轻和逆转放射和化学耐药过程。我们分析了褪黑素对头颈部鳞状细胞癌（HNSCC）细胞系（Cal-27 和 SCC-9）的影响，这些细胞系用 0.1、0.5、1 和 1.5mM 褪黑素与 8Gy 照射或 10μM 顺铂联合处理。进行集落形成和 MTT 测定，以及涉及流式细胞术和蛋白质印迹的自噬和细胞凋亡，以确定治疗的细胞毒性作用。通过测量线粒体呼吸、mtDNA 含量（RT-PCR）和线粒体质量（NAO）来评估线粒体功能。使用荧光法分析 ROS 产生、抗氧化酶活性和 GSH/GSSG 水平。我们表明，高浓度褪黑素增强了 HNSCC 中的放射治疗和 CDDP 的细胞毒性作用，这与这些细胞中线粒体功能的增加有关。在 HNSCC 中，褪黑素诱导细胞内 ROS，其积累在线粒体介导的细胞凋亡和自噬中起上游作用。我们的研究结果表明，高浓度的褪黑素与顺铂和放射治疗联合使用以提高其疗效，是一种潜在的辅助剂。
