Isham Crescent R, Netzel Brian C, Bossou Ayoko R, Milosevic Dragana, Cradic Kendall W, Grebe Stefan K, Bible Keith C
Division of Medical Oncology (C.R.I., A.R.B., K.C.B.), Department of Oncology, and Department of Laboratory Medicine and Pathology (B.C.N., D.M., K.W.C., S.K.B.), and the Endocrine Malignancies Disease Oriented Group (C.R.I., A.R.B., S.K.G., K.C.B.), Mayo Clinic, Rochester, Minnesota 55905.
J Clin Endocrinol Metab. 2014 Jun;99(6):E936-43. doi: 10.1210/jc.2013-2658. Epub 2014 Mar 14.
Vascular endothelial growth factor-targeted kinase inhibitors have emerged as highly promising therapies for radioiodine-refractory metastatic differentiated thyroid cancer. Unfortunately, drug resistance uniformly develops, limiting their therapeutic efficacies and thereby constituting a major clinical problem.
To study acquired drug resistance and elucidate underlying mechanisms in this setting, BHP2-7 human differentiated thyroid cancer cells were subjected to prolonged continuous in vitro selection with 18 μM pazopanib, a clinically relevant concentration; acquisition of pazopanib resistance was serially assessed, with the resulting resistant cells thereafter subcloned and characterized to assess potential mechanisms of acquired pazopanib resistance.
Stable 2- to 4-fold in vitro pazopanib resistance emerged in response to pazopanib selection associated with similar in vitro growth characteristics but with markedly more aggressive in vivo xenograft growth. Selected cells were cross-resistant to sunitinib and to a lesser extent sorafenib but not to MAPK kinase (MEK1/2) inhibition by GSK1120212. Genotyping demonstrated acquisition of a novel activating KRAS codon 13 GGC to GTT (glycine to valine) mutation, consistent with the observed resistance to upstream vascular endothelial growth factor receptor inhibition yet sensitivity to downstream MAPK kinase (MEK1/2) inhibition.
Selection of thyroid cancer cells with clinically utilized therapeutics can lead to acquired drug resistance and altered in vivo xenograft behavior that can recapitulate analogous drug resistance observed in patients. This approach has the potential to lead to insights into acquired treatment-related drug resistance in thyroid cancers that can be subjected to subsequent validation in serially collected patient samples and that has the potential to yield preemptive and responsive approaches to dealing with this important clinical problem.
血管内皮生长因子靶向激酶抑制剂已成为放射性碘难治性转移性分化型甲状腺癌极具前景的治疗方法。不幸的是，耐药性会普遍出现，限制了它们的治疗效果，从而构成一个主要的临床问题。
为了研究获得性耐药并阐明其潜在机制，将BHP2-7人分化型甲状腺癌细胞用18 μM帕唑帕尼（一种临床相关浓度）进行长时间连续体外筛选；连续评估帕唑帕尼耐药性的获得情况，随后对产生的耐药细胞进行亚克隆和特性分析，以评估获得性帕唑帕尼耐药的潜在机制。
在帕唑帕尼筛选后出现了稳定的2至4倍体外帕唑帕尼耐药性，其体外生长特性相似，但体内异种移植生长明显更具侵袭性。筛选出的细胞对舒尼替尼交叉耐药，对索拉非尼的交叉耐药性较低，但对GSK1120212抑制丝裂原活化蛋白激酶（MEK1/2）不耐药。基因分型显示获得了一种新的KRAS激活密码子13从GGC到GTT（甘氨酸到缬氨酸）的突变，这与观察到的对上游血管内皮生长因子受体抑制的耐药性以及对下游丝裂原活化蛋白激酶（MEK1/2）抑制的敏感性一致。
用临床使用的治疗方法筛选甲状腺癌细胞可导致获得性耐药，并改变体内异种移植行为，这可重现患者中观察到的类似耐药性。这种方法有可能深入了解甲状腺癌中获得性治疗相关耐药性，可在连续收集的患者样本中进行后续验证，并且有可能产生应对这一重要临床问题的先发制人和响应性方法。
