This Article Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Schmidt, B. A. Articles by Ackermann, R. Search for Related Content PubMed PubMed Citation Articles by Schmidt, B. A. Articles by Ackermann, R.

Up-Regulation of Cyclin-dependent Kinase 4/Cyclin D2 Expression but Down-Regulation of Cyclin-dependent Kinase 2/Cyclin E in Testicular Germ Cell Tumors¹

Department of Urology, Heinrich-Heine-University of Duesseldorf, 40225 Duesseldorf, Germany [B. A. S., A. R., C. S., R. A.], and Department of Urology, Hospital of the Armed Forces, 22099 Hamburg, Germany [M. H.]

Testicular germ cell tumors (GCT) characteristically display two chromosome 12 abnormalities: the isochromosome i(12p) and concomitant deletions of the long arm. Some genes important in the control of the G₁-S cell cycle checkpoint G₁-S, i.e., cyclin-dependent kinases 2 and 4, cyclin D2 are located on this chromosomal region. Therefore, testicular GCTs were analyzed as to the expression of CDK2, CDK4, CDK6, and the expression of their catalytic partners cyclins D1, D2 and E by semiquantitative reverse transcription-PCR. Cyclin D2, located on 12p, was overexpressed in 69% (31 of 45) of the tumors by a mean factor of 8, including all histological subtypes. In addition, the cyclin D2 partner CDK4 was increased in 41% (21 of 51) of all tumors by a factor of 6, most strongly in embryonal carcinomas. Sixty-four percent of the seminomas and 23% of the non-seminomas had decreased expression of CDK6 by a mean factor of 5 (P = 0.009). Statistical analysis using configural frequency analysis and regression analysis revealed that cyclin D2 and CDK4 expression were strongly correlated (r² = 0.682; P = 0.000052), whereas expression of CDK6 did not correlate with either of them (r² = 0.382; P = 0.00085). CDK2 and its catalytic partner cyclin E were down-regulated in 40% (19 of 47) and 42% (19 of 45) of the tumors, respectively, by a factor of 7 each. Western blots and immunohistochemical experiments confirmed cyclin D2 and CDK4 overrepresentation and reduced expression of cyclin E and CDK2 tumors in the few tumors under protein study. Despite its localization on 12q13, a hot spot for loss of heterozygosity in testicular GCTs (>40%), Southern blotting revealed no gross DNA alteration of the CDK2 gene. Because up-regulation of the cyclin D2/CDK4 complex and down-regulation of cyclin E/CDK2 complex were found in seminomas as well as in non-seminomas and in all tumor stages, these findings seem to be early events during tumorigenesis of testicular GCTs. Together with previous findings that retinoblastoma mRNA and protein expression is strongly decreased in these tumors, these data suggest an unusual deregulated G₁-S checkpoint as a decisive event for germ cell tumors.

This article has been cited by other articles:

				E. Susaki, K. Nakayama, and K. I. Nakayama Cyclin D2 Translocates p27 out of the Nucleus and Promotes Its Degradation at the G0-G1 Transition Mol. Cell. Biol., July 1, 2007; 27(13): 4626 - 4640. [Abstract] [Full Text] [PDF]

				I. M. Veltman, L. A. Vreede, J. Cheng, L. H.J. Looijenga, B. Janssen, E. F.P.M. Schoenmakers, E. T.H. Yeh, and A. G. van Kessel Fusion of the SUMO/Sentrin-specific protease 1 gene SENP1 and the embryonic polarity-related mesoderm development gene MESDC2 in a patient with an infantile teratoma and a constitutional t(12;15)(q13;q25) Hum. Mol. Genet., July 15, 2005; 14(14): 1955 - 1963. [Abstract] [Full Text] [PDF]

				T. Virolle, A. Krones-Herzig, V. Baron, G. De Gregorio, E. D. Adamson, and D. Mercola Egr1 Promotes Growth and Survival of Prostate Cancer Cells. IDENTIFICATION OF NOVEL Egr1 TARGET GENES J. Biol. Chem., March 28, 2003; 278(14): 11802 - 11810. [Abstract] [Full Text] [PDF]

				V. Bourdon, F. Naef, P. H. Rao, V. Reuter, S. C. Mok, G. J. Bosl, S. Koul, V. V. V. S. Murty, R. S. Kucherlapati, and R. S. K. Chaganti Genomic and Expression Analysis of the 12p11-p12 Amplicon Using EST Arrays Identifies Two Novel Amplified and Overexpressed Genes Cancer Res., November 1, 2002; 62(21): 6218 - 6223. [Abstract] [Full Text] [PDF]