Hu Je-Ming, Chang Yung-Lung, Hsieh Cheng-Chih, Huang Shih-Ming
Institute of Medical Sciences, National Defense Medical Center, Taipei, Taiwan.
Department of Surgery, Division of Colorectal Surgery, Tri-Service General Hospital, National Defense Medical Center, Taipei, Taiwan.
Front Oncol. 2022 Jun 7;12:925653. doi: 10.3389/fonc.2022.925653. eCollection 2022.
Colorectal cancer (CRC) ranks third in the United States for incidence or mortality. Surgical resection is the primary treatment for patients at an early stage, while patients with advanced and metastatic CRC receive combined treatment with chemotherapy, radiotherapy, or targeted therapy. C-RAF plays a key role in maintaining clonogenic and tumorigenic capacity in CRC cells and it might be a potential therapeutic target for CRC. Sorafenib is a popular oral multi-kinase inhibitor, including a B-RAF inhibitor that targets the RAF-MEK-ERK pathway. Sorafenib, as a single agent, has tumor-suppressing efficacy, but its clinical application is limited due to many complex drug resistance mechanisms and side effects. GW5074 is one of the C-RAF inhibitors and has the potential to enhance the efficacy of existing cancer chemotherapies. In this study, we investigated whether the combination of sorafenib with GW5074 could reduce the dosage of sorafenib and enhance its tumor-suppressive effect in two CRC cell lines, HCT116 and LoVo cells. Our findings demonstrate that GW5074 can potentiate the cytotoxicity of sorafenib and dramatically reduce the half-maximal inhibitory concentration (IC50) dose of sorafenib from 17 and 31 µM to 0.14 and 0.01 µM in HCT116 and LoVo cells, respectively. GW5074, similar to sorafenib, suppressed the cellular proliferation and induced cellular apoptosis and cytosolic ROS, but had no further enhancement on the above-mentioned effects when combined with sorafenib. The synergistic effects of GW5074 and sorafenib were mainly found in mitochondrial functions, including ROS generation, membrane potential disruption, and fission-fusion dynamics, which were examined by using the flow cytometry analysis. In summary, the C-RAF inhibitor GW5074 might potentiate the cytotoxicity of the B-RAF inhibitor sorafenib mediated through mitochondrial dysfunctions, suggesting that GW5074 potentially serves as a sensitizer for sorafenib application to reduce the risk of drug resistance of CRC treatment. Our findings also provide novel insights on using C-RAF inhibitors combined with sorafenib, the current CRC therapeutic drug choice, in CRC treatment.
结直肠癌（CRC）在美国的发病率和死亡率中排名第三。手术切除是早期患者的主要治疗方法，而晚期和转移性CRC患者则接受化疗、放疗或靶向治疗的联合治疗。C-RAF在维持CRC细胞的克隆形成能力和致瘤能力方面起关键作用，它可能是CRC的一个潜在治疗靶点。索拉非尼是一种常用的口服多激酶抑制剂，包括一种靶向RAF-MEK-ERK途径的B-RAF抑制剂。索拉非尼作为单一药物具有肿瘤抑制作用，但其临床应用因许多复杂的耐药机制和副作用而受到限制。GW5074是C-RAF抑制剂之一，具有增强现有癌症化疗疗效的潜力。在本研究中，我们研究了索拉非尼与GW5074联合使用是否能降低索拉非尼的剂量，并增强其在两种CRC细胞系HCT116和LoVo细胞中的肿瘤抑制作用。我们的研究结果表明，GW5074可以增强索拉非尼的细胞毒性，并将索拉非尼在HCT116和LoVo细胞中的半数最大抑制浓度（IC50）剂量分别从17和31μM显著降低至0.14和0.01μM。与索拉非尼类似，GW5074抑制细胞增殖，诱导细胞凋亡和胞质活性氧，但与索拉非尼联合使用时对上述作用没有进一步增强。GW5074和索拉非尼的协同作用主要体现在线粒体功能方面，包括活性氧生成、膜电位破坏和分裂融合动力学，这些通过流式细胞术分析进行检测。总之，C-RAF抑制剂GW5074可能通过线粒体功能障碍增强B-RAF抑制剂索拉非尼的细胞毒性，这表明GW5074有可能作为索拉非尼应用的增敏剂，以降低CRC治疗中耐药的风险。我们的研究结果也为在CRC治疗中使用C-RAF抑制剂与目前的CRC治疗药物索拉非尼联合使用提供了新的见解。
