Ret/PTC chimeric transcripts in an Irish cohort of sporadic papillary thyroid carcinoma.

Abstract

Ret rearrangements are common in papillary thyroid carcinoma (PTC), with ret/PTC-3 commonly seen in children exposed to ionizing radiation. In this context ret/PTC-3 has been correlated with solid variant morphology, poorer prognosis, and aggressive tumor behavior. We aimed to assess the prevalence of the common ret chimeric transcripts (ret/PTC-1 and ret/PTC-3) in a group of sporadic PTC and correlate them with tumor morphology. Thyroid follicular cells were laser capture microdissected from sections of archival PTC (n = 28). Total RNA was extracted and analyzed for expression of glyceraldehyde 3-phosphate dehydrogenase, ret/PTC-1, and ret/PTC-3 using TaqMan PCR. Ret/PTC rearrangements were detected in 60% of PTCs. Specifically transcripts of ret/PTC-1 and ret/PTC-3 were detected in 43% and 18% of PTCs, respectively. Ret/PTC-3 was detected in only follicular variant subtype (60%) and was not detected in classic PTC. One case of tall cell variant demonstrated chimeric expression of both ret/PTC-1 and ret/PTC-3 transcripts within the same tumor. This study demonstrated a high prevalence of the two common ret rearrangements in an Irish cohort of PTCs. A correlation of tumor morphology with these common ret rearrangements is suggested.