Molecular alterations of coexisting thyroid papillary carcinoma and anaplastic carcinoma: identification of TERT mutation as an independent risk factor for transformation

Abstract

Thyroid papillary carcinoma is the most common endocrine neoplasm and generally carries a favorable prognosis. However, a small subset of papillary carcinomas transforms into anaplastic carcinoma, an undifferentiated cancer with a dismal prognosis. Recent studies using next-generation sequencing revealed the genomic landscape of papillary carcinoma and anaplastic carcinoma. However, risk factors for anaplastic transformation in papillary carcinoma remain obscure. In the present study, we investigated molecular alterations of papillary carcinoma and anaplastic carcinoma components in 27 tumors in which anaplastic carcinoma coexisted with antecedent papillary carcinoma. We conducted direct sequencing for BRAF, TERT promoter and PIK3CA, and immunohistochemistry for p53, TTF-1 and subunits of the SWI/SNF complex (ARID1A, ARID1B, ATRX, SMARCA2, SMARCA4, SMARCB1, and PBRM1). BRAF and TERT promoter mutated at the rate of 90% and 95%, respectively, and these mutational statuses were almost identical between the papillary carcinoma and anaplastic carcinoma components. PIK3CA mutation was positive in 33% of our samples with a heterogeneous mutation pattern of the papillary carcinoma and anaplastic carcinoma components. Aberrant expression of p53 and loss of TTF-1 were present in 63 and 59%, respectively, and these two alterations were confined to the anaplastic carcinoma components. There was a loss of the SWI/SNF complex in a subset of the tumors with a heterogeneous pattern of the papillary carcinoma and anaplastic carcinoma components: SMARCA4 in 4% and PBRM1 in 4%. In a multivariate comparison between the antecedent papillary carcinoma components and control papillary carcinomas without anaplastic transformation, TERT promoter mutation was independently associated with anaplastic transformation. Collectively, papillary carcinoma-derived anaplastic carcinomas are characterized by BRAF and TERT promoter mutations, and these mutations occur prior to anaplastic transformation. Alterations of PIK3CA and the SWI/SNF complex are relatively rare and temporally heterogeneous. Of note, a papillary carcinoma harboring TERT promoter mutation is at higher risk for anaplastic transformation.

Targeted next‑generation sequencing of cancer‑related genes in thyroid carcinoma: A single institution's experience

“…Several other studies have agreed with this hypothesis, reporting associations between development of PC and increased expression of several tumor promoting molecules, including vimentin (49), matrix metalloproteinase (50), nuclear factor-κB (51), prohibitin (52), vascular endothelial growth factor (53), and hepatocyte growth factor receptor (54). A recent report indicated that the telomerase reverse transcriptase (TERT) promoter is a poor prognostic factor in patients with PC (55).…”

Clinicopathological significance of the single nucleotide polymorphism, rs2853669 within the TERT promoter in papillary thyroid carcinoma

“…Yabuta et al did not find TERT promoter mutations in papillary thyroid microcarcinomas. Therefore, we believe TERT promoter mutations may not be implicated in the development of PTCs but may be related to the growth of PTC tumors, as well as transformation to anaplastic carcinoma …”

<i>BRAF</i> and <i>TERT</i> promoter mutations: clinical application in thyroid cancer

“…BRAF mutation has been known to be associated with iodine intake, but TERT promoter mutation is not [78]. In a multivariate comparison between the PTC with and without anaplastic transformation, TERT promoter mutation was independently associated with anaplastic transformation [79]. Collectively, PTC-derived ATCs are characterized by BRAF and TERT promoter mutations, and these mutations occur prior to anaplastic transformation.…”