Gene expression analysis comparing between pure- and mixed type testicular seminoma

We hypothesized that the comparison between pure type seminoma and seminoma components in mixed tumor (mixed type seminoma) could reveal early changes of the reprogramming process; however, only a little data is available. We performed gene expression microarray analysis of 6 pure type and 6 mixed type seminomas, and the hierarchical clustering analysis properly grouped each type of seminomas into a separated cluster. Supervised analysis between these groups identified 154 significantly dysregulated genes (Storey-adjusted q < 0.05). The genes with the highest overexpression in mixed type seminomas compared with the pure type seminomas included MT1 isoforms, PRSS8, TSC22D1, and SLC39A4; down-regulated genes included DEFB123, LMTK2, and MTRF. Functional annotation analysis of the differently expressed genes revealed the top-ranking categories related to cellular zinc metabolism, consisting of MT-1 isoforms and SLC39A4. Twelve cases of primary testicular germ cell tumor, consisting of 6 pure seminomas and 6 mixed tumors with seminoma and non-seminomatous components, were identified from the files of the Department of Laboratory Medicine, National Defense Medical College Hospital. All the cases were surgically resected specimens obtained from 2015 to 2019.