Klemke Markus, Drieschner Norbert, Laabs Anne, Rippe Volkhard, Belge Gazanfer, Bullerdiek Jörn, Sendt Wolfgang
Center for Human Genetics, University of Bremen, Germany.
Cancer Genet. 2011 Jun;204(6):334-9. doi: 10.1016/j.cancergen.2011.05.001.
The chromosomal translocation t(2;3)(q13;p25) characterizes a subgroup of tumors originating from the thyroid follicular epithelium and was initially discovered in a few cases of adenomas. Later, a fusion of the genes PAX8 and PPARG resulting from this translocation was frequently observed in follicular carcinomas and considered as a marker of follicular thyroid cancer. According to subsequent studies, however, this rearrangement is not confined to carcinomas but also occurs in adenomas, with considerably varying frequencies. Only five cases of thyroid adenomas with this translocation detected by conventional cytogenetics have been documented. In contrast, studies using reverse-transcription polymerase chain reaction (RT-PCR) detected fusion transcripts resulting from that translocation in an average of 8.2% of adenomas. The aim of this study was to determine the frequency of the PAX8-PPARG fusion in follicular adenomas and to use the HMGA2 mRNA level of such tumors as an indicator of malignancy. In cytogenetic studies of 192 follicular adenomas, the t(2;3)(q13;p25) has been identified in only two cases described herein. Histopathology revealed no evidence of malignancy in either case, and, concordantly, HMGA2 mRNA levels were not elevated. In summary, the fusion is a rare event in follicular adenomas and its prevalence may be overestimated in many RT-PCR-based studies.
染色体易位t(2;3)(q13;p25)是源自甲状腺滤泡上皮的肿瘤亚群的特征，最初在少数腺瘤病例中被发现。后来，这种易位导致的PAX8和PPARG基因融合在滤泡癌中经常被观察到，并被视为甲状腺滤泡癌的标志物。然而，根据后续研究，这种重排不仅局限于癌，也发生在腺瘤中，频率差异很大。通过传统细胞遗传学检测到这种易位的甲状腺腺瘤仅有5例被记录在案。相比之下，使用逆转录聚合酶链反应（RT-PCR）的研究平均在8.2%的腺瘤中检测到了由该易位产生的融合转录本。本研究的目的是确定滤泡性腺瘤中PAX8-PPARG融合的频率，并将此类肿瘤的HMGA2 mRNA水平用作恶性肿瘤的指标。在对192例滤泡性腺瘤的细胞遗传学研究中，仅在本文所述的2例中发现了t(2;3)(q13;p25)。组织病理学显示这两例均无恶性证据，相应地，HMGA2 mRNA水平也未升高。总之，这种融合在滤泡性腺瘤中是罕见事件，在许多基于RT-PCR的研究中其发生率可能被高估了。
