Department of Thyroid and Breast Surgery, Peking University Shenzhen Hospital, ShenZhen Peking University-The Hong Kong University of Science and Technology Medical Centre, No.1120, LianHua Road, FuTian district, Shenzhen, 518036, China.
Department of Merchandising, Walmart (China) Investment Co., Ltd, Shenzhen, China.
J Exp Clin Cancer Res. 2021 Jan 19;40(1):34. doi: 10.1186/s13046-021-01831-y.
BRAFV600E mutation is the most common mutation in thyroid cancer. It strongly activates MAPK/ERK pathway and indicates an invasive subtype of thyroid cancer. PLX4032 is a selective oral inhibitor of the BRAFV600 kinase although with limited effect in treating this panel of thyroid cancer, due to the feedback activation of MAPK/ERK as well as PI3K/AKT pathways. It was investigated that Vitamin C plays a positive role in inhibiting these pathways in thyroid cancer. However, whether Vitamin C could enhance the antitumor effect of PLX4032 remains largely unclear.
The antitumor efficacy of combination therapy with PLX4032 and Vitamin C on BRAF thyroid cancer cell was assessed by the MTT assay, EdU assay and colony formation, Chou-Talalay way was employed to analyze the synergistic effect. Flow cytometry were employed to assess cells' apoptosis and cell cycle arrest in response to combination therapy. Xenograft models were used to test its in vivo antitumor activity. Western blot and IHC were applied to investigate the mechanism underlying synergistic effect.
PLX4032 or Vitamin C monotherapy was mildly effective in treating BRAF thyroid cancer cell and xenografts model. The combination therapy significantly inhibited cancer cell proliferation and tumor growth in nude mice, and induced cell apoptosis and cell cycle arrest compared to either monotherapy. PLX4032 monotherapy induced feedback activation of MAPK/ERK as well as PI3K/AKT pathway; while combination therapy significantly relieved this feedback.
Vitamin C promotes the antitumor effect of PLX4032 in BRAF thyroid cancer cell and xenografts model via relieving the feedback activation of MAPK/ERK as well as PI3K/AKT pathway. PLX4032/Vitamin C combination may be a potential therapeutic approach to treat BRAF thyroid cancer.
BRAFV600E 突变是甲状腺癌中最常见的突变。它强烈激活 MAPK/ERK 通路，并提示甲状腺癌为侵袭性亚型。PLX4032 是 BRAFV600 激酶的选择性口服抑制剂，但由于 MAPK/ERK 和 PI3K/AKT 通路的反馈激活，对这组甲状腺癌的治疗效果有限。研究表明，维生素 C 在抑制甲状腺癌细胞中的这些通路方面发挥积极作用。然而，维生素 C 是否能增强 PLX4032 的抗肿瘤作用在很大程度上仍不清楚。
通过 MTT 分析、EdU 分析和集落形成实验评估 PLX4032 和维生素 C 联合治疗 BRAF 甲状腺癌细胞的抗肿瘤疗效，采用 Chou-Talalay 方法分析协同作用。流式细胞术评估联合治疗对细胞凋亡和细胞周期阻滞的影响。异种移植模型用于测试其体内抗肿瘤活性。Western blot 和 IHC 用于研究协同作用的机制。
PLX4032 或维生素 C 单药治疗对 BRAF 甲状腺癌细胞和异种移植模型均有轻度疗效。与单药治疗相比，联合治疗显著抑制了裸鼠中癌细胞的增殖和肿瘤生长，并诱导了细胞凋亡和细胞周期阻滞。PLX4032 单药治疗诱导了 MAPK/ERK 和 PI3K/AKT 通路的反馈激活；而联合治疗则显著缓解了这种反馈。
维生素 C 通过缓解 MAPK/ERK 和 PI3K/AKT 通路的反馈激活，促进了 PLX4032 在 BRAF 甲状腺癌细胞和异种移植模型中的抗肿瘤作用。PLX4032/维生素 C 联合治疗可能是治疗 BRAF 甲状腺癌的一种潜在治疗方法。
