Sub theme 3.1.1
Germ Cell Tumors

Goals of research: general outline
Scientific achievements
Future plans: special goals and approach
Running projects
Associated staff

Goals of research: general outline

Understanding at the molecular level of the peculiar aspects of the pathobiology of germ cell tumors with emphasis on Type 2 germ cell tumors (seminomas and non-seminomas):

- origin during the early development;

- genetic events causing to progression, i.p. the changes on 12p;

- remarkable treatment sensitivity and resistance in rare cases.

Early events will be studied in dysgenetic gonads of patients with various disorders of sex differentiation, as this approach has been successful in the recent past. The role of amplifications on 12p will be studie with state of the high through-put approaches, o.a. deep sequencing. Increasing understanding of the role of cancer stem cells in resistance to treatment renews the interest in the characteristics of embryonal carcinoma cells, the stem cells of nonseminomas that make them so sensitive to chemotherapy. The general approach will be to compare adult stem cells to embryonal carcinoma cells. In addition, the various spontaneous and induced in vitro and in vivo model systems will be investigated for their value to understand the pathobiology of human germ cell tumors.

Scientific achievements

The first, and as yet only, seminoma cell line (TCAM-2) was characterized. Its BRAF mutation most probably explains why it survives in vitro.

Overexpression of DMRT1 was identified as an important genetic event in the causation of spermatocytic seminoma (Type 3 germ cell tumor). DMRT1 was established as a useful immunohistochemical marker for the diagnosis of spermatocytic seminoma.

OCT3/4 was successfully applied to detect cancer cells in the semen of patients with Type 2 germ cell tumors of the testis.

Application of novel markers for germ cell differentiation to the study of differentiation lineages allowed the detection of germ lineage differentiation in Type 2 nonseminomatous germ cell tumors. Study of the earliest stages of the development of Type 2 germ cell tumors in dysgenetic gonads demonstrated the significance of persistent co-expression of OCT3/4 and TSPY in maturation-delayed gonocytes, and the expression of SCF (either paracrine or autocrine) for tumor development. In addition our study of gonadal dysgenesis resulted in a new classification of disorders of sex development (DSD) allowing better prediction of the risk of developing a Type 2 germ cell tumor.

Further studies on therapy resistance confirmed the importance of MSI in a substantially extended patient material. New is the finding that BRAF mutations also predict therapy resistance. Mutated BRAF is involved in MSI.

The reason why P53 is almost always wild type in Type 2 germ cell tumors was discovered in a collaboration with investigators of the Netherlands Cancer Institute: the downstream target of P53 being LATS2 is functionally inactivated by miR-372 and 373 due interference of these miRNA’s  (Voorhoeve et al., Cell 2006).

It was demonstrated that OCT3/4 is co-expressed with SOX17 in carcinoma in situ and seminoma cells, and with SOX2 in embryonal carcinoma cells. This switch of SOX-partners is accompanied by the reprogramming of a seminomatous cell into a pluripotent embryonal carcinoma cell, the neoplastic counterpart of embryonal stem cells.

Future plans: special goals and approach

Study of the earliest events in the causation of Type 2 germ cell tumors in dysgenetic gonads. In particular functional study of expression of TSPY and OCT3/4 in TCAM-2, as well as the c-KIT SCF pathway.

More accurate prediction of the risk of Type 2 germ cell tumors patients with disorders of sex development (DSD) in an internationally collected patient cohort.

The role of expression of SOX2 in the reprogramming of the seminomatous cell into a pluripotent embryonal carcinoma cell.

Mechanisms of induction of differentiation upon invasion of intratubular embryonal carcinoma; role hypoxia-induced factors a.o. c-MET.

Revisit the role 12p in the progression of Type 2 germ cell tumors by applying state of the art high through-put molecular analysis, i.p. deep-sequencing, to the amplified region.

Comparing embryonal carcinoma cells, the stem cells of Type 2 germ cell tumors, to adult stem cells to understand their exquisite therapy sensitivity.

Mechanisms and predictive factors of therapy resistance in Type 2 germ cell tumors using fresh frozen tissue of over 30 patients who failed therapy, collected over the past 20 years.

Diagnostic markers for germ cell tumors, in particular for non-invasive detection of carcinoma in situ cells in seminal fluid. Integrtal investigation of structural and numerical genomic changes, mRNA, miRNA and  protein expression in a series of stage I and II germ cell tumors. 

Most recent publications

1.      Kersemaekers AM, Mayer F, Van Weeren P, Oosterhuis JW, Bokemeyer C, Looijenga LHJ. Role of P53 and MDM2 in treatment response of human germ cell tumors. J Clin Oncol. 2002;20:1551-1561. (IF 15.48).

2.      Mayer F, Gillis AJM, Dinjens W, Oosterhuis W, Bokemeyer C, Looijenga LHJ. Microsatellite instabibility of germ cell tumors is associated with resistance to systemic treatment. Cancer Res. 2002;62:2758-2760. (IF 7.67).

3.      Looijenga LHJ, De Leeuw H, Van Oorschot M, Van Gurp RJHLM, Stoop H, Gillis AJM, De Gouveia Brazao CA, Weber RFA, Kirkels WJ, Van Dijk T, Von Lindern, Valk P, Lajos G, Olah E, Nesland JM, Fossa SD, Oosterhuis JW. Stem cell factor receptor (c-KIT) codon 816 mutations predict development of bilateral testicular germ cell tumors. Cancer Res. 2003; 63: 7674-7678. (IF 7.67).

4.      Looijenga LHJ, Stoop H, De Leeuw H,PJC, De Gouveia Brazao, Gillis AJM, Van Roozendaal KEP, Van Zoelen EJJ, Weber RFA, Wolffenbuttel KP, Van Dekken H, Honecker F, Bokemeyer C, Perlman EJ, Schneider DT, Kononen J, Sauter G, Oosterhuis JW. POU5F1 (OCT3/4) identifies cells with pluripotent potential in human germ cell tumors. Cancer Res. 2003; 63:2244-2250. (IF 7.67).

5.      Oosterhuis JW, Looijenga LHJ. Testicular germ cell tumors in a broader perspective. Nat Rev Cancer: 2005;5:210-222. (IF 29.19).

6.      Herszfeld D, Wolvetang E, Langton-Bunker E, Chung TL, Filipczyk AA, Houssami S, Jamshidi P, Koh K, Laslett AL, Michalska A, Nguyen L, Reubinoff BE, Tellis I, Auerbach JM, Ording CJ, Looijenga LHJ, Pera MF. CD30 is a survival factor and a biomarker for transformed human pluripotent stem cells. Nat. Biotechnol. 2006;24;351-357. (IF 22.80).

7.      Looijenga LHJ, Hersmus R, Gillis AJ, Pfundt R, Stoop HJ, van Gurp RJ, Veltman J, Beverloo HB, van Drunen E, van Kessel AG, Pera RR, Schneider DT, Summersgill B, Shipley J, McIntyre A, van der Spek P, Schoenmakers E, Oosterhuis JW. Genomic and expression profiling of human spermatocytic seminomas: primary spermatocyte as tumorigenic precursor and DMRT1 as candidate chromosome 9 gene. Cancer Res. 2006; 66: 290-302. (IF 7.67).

8.      Cools M, Drop SL, Wolffenbuttel KP, Oosterhuis JW, Looijenga LHJ. Germ cell tumors in the intersex gonad: Old paths, new directions, moving frontiers. Endocr Rev. 2006; 27: 468-484. (IF 18.49).

9.      Voorhoeve PM, Le Sage C, Schrier M, Gillis AJM, Stoop H, Nagel R, Liu YP, Van Duijse, Drost J, Griekspoor A, Zlotorynski E, De Vita G, Nojima N, Looijenga LHJ and Agami R. A genetic screen identifies miRNA-372 and miRNA-373 as oncogenes in testicular germ cell tumors. Cell 2006;124:1169-1181. (IF 29.90).

10.  Honecker F, Wermann H, Mayer F, Gillis AJM, Stoop H, Oechsle K, Steyerberg E, Hartmann JTh. Dinjens WNM, Oosterhuis JW, Bokemeyer C, Looijenga LHJ. Microsatellite Instability, Mismatch Repair Deficiency, And BRAF Mutation In Treatment Resistant Germ Cell Tumors. J. Clin. Oncol., in press. (IF 15.48).