IGF2BP1 is the first positive marker for anaplastic thyroid carcinoma diagnosis [sWGS]. 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. Overall design: Shallow Whole Genome sequencing of ATC samples.

间变性甲状腺癌（Anaplastic Thyroid Carcinoma, ATC）是一类罕见但致死性最高的甲状腺恶性肿瘤。目前可用于区分ATC与其他滤泡源性甲状腺癌的特异性分子标志物及驱动因子仍未明确，这限制了该病诊断与治疗领域的研究进展。本回顾性研究采用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测序数据提示了ATC特异性蛋白标志物。对上述标志物的评估显示，ATC的特征为全新表达多种睾丸抗原，包括黑色素瘤相关抗原A3（melanoma-associated antigen A3, MAGEA3），而最关键的是癌胚胰岛素样生长因子2 mRNA结合蛋白1（IGF2 mRNA binding protein 1, IGF2BP1）。浅层全基因组测序（shallow whole genome-sequencing）基本排除了IGF2BP1上调由基因拷贝数变异导致的可能性。对三个肿瘤队列的免疫组化分析证实，ATC中选择性全新表达IGF2BP1蛋白。综上，所有检测的ATC样本中75%（27/36）呈IGF2BP1蛋白阳性，而低分化与高分化甲状腺癌组织样本中仅0.5%（1/204）呈阳性。这表明IGF2BP1蛋白表达可用于识别ATC，其诊断比值比为612（95%置信区间：74.6~5021）。此外，本研究发现MAGEA3虽表达一致性稍差，但仅在ATC中上调，其比值比为411（95%置信区间：23.8~7098.7）。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是目前已知最具潜力的ATC单基因标志物，其次为MAGEA3，相较现有技术具有显著优势。可靠的分子标志物对于区分该高级别恶性肿瘤与其他甲状腺癌、指导手术决策、治疗方案以及术后/治疗后监测策略均至关重要。整体实验设计：ATC样本的浅层全基因组测序。