B-Raf激酶抑制剂，如维穆拉非尼（PLX4032）和达布拉非尼，在BRAF突变的甲状腺癌治疗中疗效有限。癌症干细胞（CSCs）在肿瘤复发、药物抵抗和转移中起着重要作用。CSCs是否在抑制B-Raf激酶抑制剂的抗肿瘤活性中发挥作用尚不清楚。在这里，我们报道说维穆拉非尼（PLX4032）诱导了两种无定形甲状腺癌细胞系SW1736和8505C中的几个干细胞相关基因的表达，包括Gli1，蜗牛，BMI1和SOX2，但降低了这些基因在人类黑素瘤细胞系A375中的表达。PLX4032促进了甲状腺癌干细胞的自我更新，如由增加的醛脱氢酶（ALDH）阳性细胞和甲状腺球体所证实。在机制上，PLX4032通过HER3活化PI-3和MAP激酶信号通路，进而通过Gli1（蜗牛的一个转录因子）激活了sonic hedgehog（Shh）信号通路。GANT61，一个特异性的Gli1抑制剂，在体外和体内抑制了PLX4032处理的甲状腺癌细胞中干细胞相关基因的表达，在两个甲状腺癌异种移植模型中也有相同的效果。单独使用GANT61治疗略微抑制了SW1736肿瘤的生长，但在与PLX4032联合使用时增强了其抗肿瘤活性。我们的研究为了解甲状腺癌不良对B-Raf激酶抑制剂的反应提供了机制上的洞察，并建议在联合作用下靶向B-Raf和Shh信号通路可能克服甲状腺癌的药物抵抗。

B-Raf kinase inhibitors such as vemurafenib (PLX4032) and dabrafenib have limited therapeutic efficacy on BRAF-mutated thyroid cancer. Cancer stem cells (CSCs) play important roles in tumor recurrence, drug resistance, and metastasis. Whether CSCs play a role in dampening the antitumor activity of B-Raf kinase inhibitors remains unknown. Here, we report that vemurafenib (PLX4032) induced the expression of several stemness-related genes including Gli1, Snail, BMI1, and SOX2 in two anaplastic thyroid cancer cell lines, SW1736 and 8505C, but decreased the expression of these genes in A375 cells, a human melanoma cell line. PLX4032 promoted thyroid cancer stem cell self-renewal, as evidenced by increased numbers of aldehyde dehydrogenase (ALDH)-positive cells and thyrospheres. Mechanistically, PLX4032 activates the PI-3 and MAP kinase pathways through HER3 to cross-activate Gli1, a transcription factor of the sonic hedgehog (Shh) pathway. GANT61, a specific inhibitor of Gli1, blocked the expression of the stemness-related genes in PLX4032-treated thyroid cancer cells in vitro and in vivo in two thyroid cancer xenograft models. GANT61 treatment alone weakly inhibited SW1736 tumor growth but enhanced the antitumor activity of PLX4032 when used in combination. Our study provides mechanistic insights into how thyroid cancer poorly responds to B-Raf kinase inhibitors and suggests that targeting B-Raf and the Shh pathway in combination may overcome thyroid cancer drug resistance.