IGF2BP1 is the first positive marker for anaplastic thyroid carcinoma diagnosis [sWGS]

Anaplastic thyroid carcinomas (ATC) are rare, but represent the most lethal malignancy of the thyroid. Selective molecular markers and drivers distinguishing ATC from other thyroid carcinomas of follicular origin remain largely unknown, limiting advances in diagnosis and treatment. In a retrospective study, we analyzed gene expression in 36 ATC, 18 poorly-differentiated, 132 papillary and 55 follicular thyroid carcinoma, as well as 124 paired and un-paired normal thyroid tissues in three independent cohorts by RNA-sequencing and immunohistochemistry. RNA-sequencing data in the test cohort suggested selective ATC protein biomarkers. Evaluation of these revealed that ATCs are characterized by the de novo expression of various testis antigens, including melanoma-associated antigen A3 (MAGEA3), but most importantly the oncofetal IGF2 mRNA binding protein 1 (IGF2BP1). Shallow whole genome-sequencing essentially excluded, that IGF2BP1 upregulation results from gene copy number alterations. Immunohistochemical analyses in all three tumor cohorts confirmed selective de novo expression of IGF2BP1 protein in ATC. In sum, 75 % (27/36) of all tested ATC and 0.5 % (1/204) of poorly and well-differentiated thyroid carcinoma tissue samples were positive for IGF2BP1 protein. This indicates that IGF2BP1 protein expression identifies ATC with a diagnostic odds ratio of 612 (95 % CI: 74.6 to 5021). In addition, we found that MAGEA3 is exclusively, although less consistently upregulated in ATC, presenting with an odds ratio of 411 (95 % CI: 23.8 to 7098.7). Importantly, we provide confirmatory evidence that IGF2BP1 and MAGEA3 expression distinguishes ATC from partially differentiated thyroid carcinomas (PDTCs). IGF2BP1 furthermore identified ATC foci within low-grade follicular thyroid carcinoma. In conclusion, IGF2BP1 represents the most promising single-gene marker available for ATC, followed by MAGEA3, improving on current techniques. Robust markers are essential to help distinguish this high-grade malignancy from other thyroid carcinomas, to guide surgical decision making, therapy and post-resection/therapy monitoring strategies. Shallow Whole Genome sequencing of ATC samples.

间变性甲状腺癌（Anaplastic Thyroid Carcinoma, ATC）较为罕见，却是致死性最强的甲状腺恶性肿瘤。目前可区分ATC与其他滤泡起源甲状腺癌的选择性分子标志物及驱动基因仍未明确，这极大限制了该病的诊疗进展。本回顾性研究通过RNA测序（RNA-sequencing）与免疫组化（immunohistochemistry）技术，在三个独立队列中分析了36例ATC、18例低分化甲状腺癌、132例乳头状甲状腺癌、55例滤泡状甲状腺癌，以及124例配对与非配对正常甲状腺组织的基因表达情况。
测试队列的RNA测序数据提示存在选择性ATC相关蛋白质生物标志物。对这些标志物的评估显示，ATC的特征为从头表达多种睾丸抗原，包括黑色素瘤相关抗原A3（MAGEA3），其中最关键的标志物为癌胚胰岛素样生长因子2 mRNA结合蛋白1（IGF2BP1）。浅层全基因组测序基本排除了IGF2BP1上调由基因拷贝数变异所致的可能。对三个肿瘤队列的免疫组化分析证实，ATC中选择性从头表达IGF2BP1蛋白。
综上，在所有检测的ATC样本中，75%（27/36）的IGF2BP1蛋白呈阳性；而在低分化与高分化甲状腺癌组织样本中，仅0.5%（1/204）呈阳性。该结果表明，IGF2BP1蛋白表达可用于识别ATC，其诊断优势比为612（95%置信区间：74.6至5021）。此外，我们发现MAGEA3虽表达一致性稍差，但仅在ATC中上调，其诊断优势比为411（95%置信区间：23.8至7098.7）。重要的是，本研究提供了验证性证据，证明IGF2BP1与MAGEA3的表达可区分ATC与部分分化型甲状腺癌（PDTCs）。IGF2BP1还可识别低级别滤泡状甲状腺癌中的ATC病灶。
综上，IGF2BP1是目前最具潜力的ATC单基因标志物，其次为MAGEA3，二者优于现有检测技术。可靠的标志物对于将这种高级别恶性肿瘤与其他甲状腺癌区分开来、指导手术决策、治疗方案以及术后/治疗后监测策略至关重要。本研究还对ATC样本进行了浅层全基因组测序。