Leendert H.J. Looijenga

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Endogenous small RNAs (miRNAs) regulate gene expression by mechanisms conserved across metazoans. While the number of verified human miRNAs is still expanding, only few have been functionally annotated. To perform genetic screens for novel functions of miRNAs, we developed a library of vectors expressing the majority of cloned human miRNAs and created(More)
Despite intense investigation of intrinsic and extrinsic factors that regulate pluripotency, the process of initial fate commitment of embryonic stem (ES) cells is still poorly understood. We used a genome-wide short hairpin RNA screen in mouse ES cells to identify genes that are essential for initiation of differentiation. Knockdown of the scaffolding(More)
The in vitro culture conditions allowing survival and initial proliferation of murine primordial germ cells from 10.5 days post coitum embryos, which include the use of a murine embryonal fibroblast (STO) feeder, were applied to 21 human seminomas, composed of tumour cells which are considered as the malignant counterparts of human primordial germ cells.(More)
The presence of the BCL-2 protein was studied in nine non-Hodgkin's lymphomas with testicular localisation. A consistent presence of the BCL-2 protein was found. The chromosomal translocation (14;18) was seen neither by cytogenetic analysis (n = 4) nor by polymerase chain reaction amplification and Southern blotting (n = 9). Therefore, this translocation is(More)
Although the receptor tyrosine kinase (RTK) MET is widely expressed in head and neck squamous cell carcinoma (HNSCC), its prognostic value remains unclear. This might be due to the use of a variety of antibodies and scoring systems. Here, the reliability of five commercial C-terminal MET antibodies (D1C2, CVD13, SP44, C-12 and C-28) was evaluated before(More)
One of the main obstacles encountered when trying to culture human seminoma (SE) cells in vitro is massive degeneration of the tumour cells. We investigated whether dissociation of tumour tissue, to obtain single-cell suspensions for in vitro culture, results in the onset of apoptosis. Using morphological analysis and in situ end labelling, less than 4% of(More)
Tyrosine-kinase inhibitors of the hepatocyte growth factor receptor MET are under investigation for the treatment of hormone-refractory prostate cancer (HRPC) metastasis. Analysis of MET protein expression and genetic alterations might contribute to therapeutic stratification of prostate cancer patients. Our objective was to investigate MET on protein, DNA(More)
The value of endoscopic Barrett esophagus (BE) surveillance based on histological diagnosis of low-grade dysplasia (LGD) remains debated given the lack of adequate risk stratification. The aim of this study was to evaluate the predictive value of cyclin A expression and to combine these results with our previously reported immunohistochemical p53, AMACR,(More)
Testicular germ cell tumours (TGCTs) of adolescents and adults morphologically mimic different stages of embryogenesis. Established cell lines of these cancers are used as informative models to study early development. We found that, in contrast to normal development, TGCTs show a consistent biallelic expression of imprinted genes, including H19,(More)
Germ cell development is influenced by activin and inhibin, which are produced by Sertoli cells. Activin also affects differentiation of mouse embryonal carcinoma cells, which, to a certain extent, resemble the embryonal carcinoma component of germ cell tumours. Therefore, the expression of inhibin/activin subunits, of activin receptors and of the(More)