Xi Su1, Peng Li1, Bin Han1, Hao Jia1, Qingzhuang Liang1, Haichao Wang1, Mengwei Gu2, Jiaxuan Cai1, Shaolei Li1, Yaqi Zhou3, Xin Yi1, Wei Wei4. 1. 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. 2. Department of Merchandising, Walmart (China) Investment Co., Ltd, Shenzhen, China. 3. Department of Otorhinolaryngology, Peking University Shenzhen Hospital, ShenZhen Peking University-The Hong Kong University of Science and Technology Medical Centre, Shenzhen, China. 4. 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. rxwei1123@163.com.
Abstract
BACKGROUND: 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. METHODS: The antitumor efficacy of combination therapy with PLX4032 and Vitamin C on BRAFMT 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. RESULTS: PLX4032 or Vitamin C monotherapy was mildly effective in treating BRAFMT 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. CONCLUSION: Vitamin C promotes the antitumor effect of PLX4032 in BRAFMT 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 BRAFMT thyroid cancer.
BACKGROUND: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. METHODS: The antitumor efficacy of combination therapy with PLX4032 and Vitamin C on BRAFMT 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. RESULTS:PLX4032 or Vitamin C monotherapy was mildly effective in treating BRAFMT 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. CONCLUSION:Vitamin C promotes the antitumor effect of PLX4032 in BRAFMT 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 BRAFMT thyroid cancer.
Entities:
Keywords:
BRAFV600E; MAPK/ERK pathway; PLX4032; Thyroid Cancer; Vitamin C