Data from DNMT3L Is a Novel Marker and Is Essential for the Growth of Human Embryonal Carcinoma

Abstract

<div>Abstract<p><b>Purpose:</b> Testicular germ cell tumors (TGCT) have a unique epigenetic profile distinct from that of other types of cancer. Elucidation of these properties has a potential to identify novel markers for TGCTs.</p><p><b>Experimental Design:</b> We conducted comprehensive analysis of <i>DNA methyltransferase</i> (<i>DNMT</i>) gene expression in TGCTs. Based on the expression profiles of <i>DNMT</i> genes in TGCTs, we generated a rabbit polyclonal anti-human DNMT3L antibody. We then studied the role of DNMT3L in TGCTs by the treatment of two embryonal carcinoma (EC) cell lines with a small interfering RNA system. Finally, we evaluated the immunohistochemical detection of DNMT3L in TGCT tissues. We also compared the patterns of DNMT3L immunohistochemistry with those of CD30 and SOX2.</p><p><b>Results:</b> Among the <i>DNMT</i> genes, we found that mRNA for <i>DNMT3L</i> was specifically expressed in TGCTs, but neither in normal testicular tissues nor in cancer cells of somatic tissue origin. DNMT3L protein was strongly expressed in two EC cell lines, but not in the cell lines of somatic tissue origin. Transfection of small interfering RNA for <i>DNMT3L</i> significantly reduced DNMT3L expression and resulted in growth suppression and apoptosis in EC cells. Immunohistochemical analysis showed that DNMT3L protein was present only in EC cells, but not in the other types of TGCT components and cancer cells of somatic tissue origin. DNMT3L staining was more prominent and specific than CD30 or SOX2 staining for detecting EC cells.</p><p><b>Conclusion:</b> DNMT3L is a novel marker and is essential for the growth of human embryonal carcinoma. Clin Cancer Res; 16(10); 2751–9. ©2010 AACR.</p></div>