HMGA2 expression distinguishes between different types of postpubertal testicular germ cell tumour.

The group of postpubertal testicular germ cell tumours encompasses lesions with highly diverse differentiation - seminomas, embryonal carcinomas, yolk sac tumours, teratomas and choriocarcinomas. Heterogeneous differentiation is often present within individual tumours and the correct identification of the components is of clinical relevance. HMGA2 re-expression has been reported in many tumours, including testicular germ cell tumours. This is the first study investigating HMGA2 expression in a representative group of testicular germ cell tumours with the highly sensitive method of quantitative real-time PCR as well as with immunohistochemistry. The expression of HMGA2 and HPRT was measured using quantitative real-time PCR in 59 postpubertal testicular germ cell tumours. Thirty specimens contained only one type of tumour and 29 were mixed neoplasms. With the exception of choriocarcinomas, at least two pure specimens from each subgroup of testicular germ cell tumour were included. In order to validate the quantitative real-time PCR data and gather information about the localisation of the protein, additional immunohistochemical analysis with an antibody specific for HMGA2 was performed in 23 cases. Expression of HMGA2 in testicular germ cell tumours depended on the histological differentiation. Seminomas and embryonal carcinomas showed no or very little expression, whereas yolk sac tumours strongly expressed HMGA2 at the transcriptome as well as the protein level. In teratomas, the expression varied and in choriocarcinomas the expression was moderate. In part, these results contradict data from previous studies but HMGA2 seems to represent a novel marker to assist pathological subtyping of testicular germ cell tumours. The results indicate a critical role in yolk sac tumours and some forms of teratoma.

Detection of PAX8-PPARG fusion transcripts in archival thyroid carcinoma samples by conventional RT-PCR.

The t(2;3)(q13;p25) occurs in a subgroup of follicular-patterned thyroid tumors and leads to a fusion of the genes encoding for the thyroid-specific transcription factor paired box 8 (PAX8) and the peroxisome proliferator-activated receptor gamma (PPARγ). Although initially discovered in follicular carcinomas (FTC), the fusion transcripts were also detected in a small fraction of follicular adenomas and rarely in follicular variants of papillary carcinomas (FV-PTC). In most RT-PCR based studies, fresh or snap-frozen tissue samples were used. The aim of the present study was to develop a method for the detection of chimeric PAX8-PPARG transcripts in formalin-fixed paraffin-embedded (FFPE) thyroid tumor samples by conventional RT-PCR. For this purpose, RNA from FFPE samples of 21 FTC, seven FV-PTC, and one bone metastasis derived from an FTC was subjected to RT-PCR with subsequent gel electrophoretic separation of the products. Fusion transcripts were detected in 2/21 primary FTC (9.5%) and in the bone metastasis, but they were undetectable in all seven FV-PTC under investigation. The RT-PCR approach described herein allows to detect all known variants of PAX8-PPARG fusion transcripts and is applicable to FFPE tissues. Thus, it can be used to screen archival thyroid tumor samples for the gene fusion.

Decrease in thyroid adenoma associated (THADA) expression is a marker of dedifferentiation of thyroid tissue.

BACKGROUND: Thyroid adenoma associated (THADA) has been identified as the target gene affected by chromosome 2p21 translocations in thyroid adenomas, but the role of THADA in the thyroid is still elusive. The aim of this study was to quantify THADA gene expression in normal tissues and in thyroid hyper- and neoplasias, using real-time PCR. METHODS: For the analysis THADA and 18S rRNA gene expression assays were performed on 34 normal tissue samples, including thyroid, salivary gland, heart, endometrium, myometrium, lung, blood, and adipose tissue as well as on 85 thyroid hyper- and neoplasias, including three adenomas with a 2p21 translocation. In addition, NIS (sodium-iodide symporter) gene expression was measured on 34 of the pathological thyroid samples. RESULTS: Results illustrated that THADA expression in normal thyroid tissue was significantly higher (p < 0.0001, exact Wilcoxon test) than in the other tissues. Significant differences were also found between non-malignant pathological thyroid samples (goiters and adenomas) and malignant tumors (p < 0.001, Wilcoxon test, t approximation), anaplastic carcinomas (ATCs) and all other samples and also between ATCs and all other malignant tumors (p < 0.05, Wilcoxon test, t approximation). Furthermore, in thyroid tumors THADA mRNA expression was found to be inversely correlated with HMGA2 mRNA. HMGA2 expression was recently identified as a marker revealing malignant transformation of thyroid follicular tumors. A correlation between THADA and NIS has also been found in thyroid normal tissue and malignant tumors. CONCLUSIONS: The results suggest THADA being a marker of dedifferentiation of thyroid tissue.

6p21 rearrangements in uterine leiomyomas targeting HMGA1.

To quantify the expression of HMGA1 mRNA in uterine leiomyomas, the expression of HMGA1 was analyzed in a series including tumors with aberrations of chromosome 6 (n = 7) and cytogenetically normal tumors (n = 8) as a control group by quantitative reverse transcriptase-polymerase chain reaction. The average expression level in the 6p21 group was found to be 5.6 times higher than that in the control group, and with one exception, all cases with 6p21 alteration revealed a high expression of HMGA1 mRNA than cytogenetically normal tumors. Nevertheless, compared to fibroids with a normal karyotype, the upregulation of the HMGA1 mRNA in these cases was much less strong than that of HMGA2 mRNA in case of 12q14∼15 aberrations identified in previous studies.

Upregulation of HMGA2 in thyroid carcinomas: a novel molecular marker to distinguish between benign and malignant follicular neoplasias.

The identification of molecular markers allowing to differentiate between benign and malignant thyroid tumors remains a diagnostic challenge. Herein, we have used the expression of the high mobility group protein gene HMGA2 and its protein, respectively, as a possible marker detecting malignant growth of thyroid tumors. HMGA2 belongs to the high mobility group proteins, i.e. small, highly charged DNA-binding proteins. While HMGA2 is highly expressed in most embryonic tissues, its expression in adult tissues is very low. However, a reactivation of HMGA2 expression has been described for various malignant tumors and often correlates with the aggressiveness of the tumors. The aim of this study was to investigate whether the HMGA2 expression can be used to detect malignant thyroid tumors. RNA from 64 formalin-fixed paraffin-embedded thyroid tissues including normal tissue (n = 3), thyroiditis (n = 2), and follicular adenomas (n = 19) as well as follicular (n = 9), papillary (n = 28), and anaplastic (n = 3) carcinomas was reverse transcribed. Finally, real-time quantitative RT-PCR was performed. Expression differences of up to 400-fold were detected between benign and malignant thyroid tumors. Based on HMGA2 expression alone, it was possible to distinguish between benign and malignant thyroid tissues with a sensitivity of 95.9% and a specificity of 93.9%. There was a highly significant (P < 0.001) difference with histology of the tumors being the gold standard between the benign lesions and malignant tumors. Our results show that even as a stand-alone marker HMGA2 expression has a high potential to improve diagnoses of follicular neoplasms of the thyroid.