Siegfried Loeschke

HMGA2 overexpression in non‐small cell lung cancer

Lung cancer is still the leading cause of death from cancer worldwide primarily because of the fact that most lung cancers are diagnosed at advanced stages. Overexpression of the high mobility group protein HMGA2 has been observed in a variety of malignant tumors and often correlates with poor prognosis. Herein, HMGA2 expression levels were analyzed in matching cancerous and non‐cancerous lung samples of 17 patients with adenocarcinoma (AC) and 17 patients with squamous cell carcinoma (SCC) with real‐time quantitative RT‐PCR (qRT‐PCR). Transcript levels were compared to results obtained by immunohistochemistry (IHC). HMGA2 expression was detectable by qRT‐PCR in all samples tested and varied from 5422 to 16 991 545 copies per 250 ng total RNA in the carcinoma samples and from 289 to 525 947 copies in the non‐cancerous tissue samples. In 33/34 non‐small cell lung cancer (NSCLC) samples tested, an overexpression of HMGA2 was revealed with statistically highly significant differences between non‐neoplastic and tumor samples for both AC (P < 0.0001) as well as for SCC (P < 0.0001). Expression varies strongly and is increased up to 911‐fold for AC and up to 2504‐fold for SCC, respectively, with statistically significant higher increase in SCC (P < 0.05). The results presented herein indicate that HMGA2 overexpression is a common event in NSCLC and could serve as molecular marker for lung cancer.

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.

Enhanced molecular analyses by combination of the HOPE-technique and laser microdissection

As part of an investigation aimed at illuminating the possibilities and limits of the HOPE-fixation and paraffin-embedding technique we here describe a novel procedure which was developed in order to combine the benefits of the HOPE-technique with the capabilities of laser microdissection. The presented procedure avoids the need for amplification of template-RNA thus facilitating reliable and reproducible results. The excellent preservation of nucleic acids, proteins, and morphology in HOPE-fixed, paraffin-embedded tissues enhances the molecular applications available to date with materials acquired by laser microdissection when compared to formalin fixed, paraffin-embedded tissues, thus substantially extending the methodological panel in tissue based research.

Cost-effective gel documentation using a web-cam

In search for a cost effective gel documentation system applicable for different fields of molecular biology, we analyzed the capabilities of a cheap CCD-camera originally designed to capture images for transmission through the internet (web-cam) with regard to gel documentation. The camera was connected to a personal computer by universal serial bus (USB) and used for the documentation of DNA separated on agarose gels and stained by ethidium-bromide using the software provided with the camera. The web-cam provided digital images of sufficient quality for routine documentation and combined the low set-up costs of a Polaroid system with the low running costs of video capture systems, hence is ideal as a start-up system and as augmentation to existing equipment.

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

BackgroundThyroid 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.MethodsFor 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.ResultsResults 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.ConclusionsThe results suggest THADA being a marker of dedifferentiation of thyroid tissue.