[804] Overexpression of TCL1 in Testicular Germ Cell Tumors

D Cao, RW Allan, CC Guo, Y Peng, J Li. Washington University School of Medicine, Saint Louis; University of FLorida, Gainesville; The University of Texas-MD Anderson Cancer Center, Houston; The University of Texas-Southwestern Medical Center, Dallas

Background: The T cell leukemia/lymphoma 1 (TCL1) gene plays an important role in early embryogenesis. Recent studies have shown that in embryonic stem cells TCL1 is regulated by OCT3/4. OCT3/4 has been shown to be a sensitive diagnostic marker for testicular germ cell tumors (GCTs). The purpose of this study is to investigate the diagnostic utility of TCL1 in testicular GCTs.
Design: 88 primary [61 pure and 27 mixed, 47 with intratubular germ cell neoplasias (ITGCNs)] and 62 metastatic testicular GCTs (tumor type and component in tables 1 and 2) were retrieved for immunohistochemical staining with a TCL1 antibody. The percentage of tumor cells stained was scored semiquantitatively as: 0 (no tumor cell staining), 1+ (<=30%), 2+ (31-60%), 3+ (61-90%), and 4+ (>90%).
Results: The staining results with TCL1 were summarized in table 1 (primary) and table 2 (metastatic).

TCL1 immunostaining in 88 primary testicular GCTs

Tumor (pure or component)	Staining Pattern
	0	1+	2+	3+	4+
ITGCNs (N=47)	0	0	0	0	47 (100%)
seminomas (N=51)	0	1(2%)	2 (4%)	2 (4%)	46 (88%)
Spermatocytic seminomas (N=5)	5 (100%)	0	0	0	0
ECs (N=32)	29 (91%)	3 (9%)	0	0	0
YSTs (N=25)	25 (100%)	0	0	0	0
Teratomas (N=20)	20 (100%)	0	0	0	0
Choriocarcinomas (N=3)	2 (67%)	1(33%)	0	0	0

TCL1 immunostaining in 62 metastatic testicular GCTs

Tumor type	Staining Pattern
	0	1+	2+	3+	4+
Seminomas (N=19)	1(5%)	4(21%)	3 (16%)	2 (10%)	9 (47%)
ECs (N=19)	19 (100%)
YSTs (N=8)	8 (100%)
Teratomas (N=11)	11 (100%)
Choriocarcinomas (N=5)	5 (100%)

The staining pattern was nuclear and cytoplasmic. TCL1 staining was seen in 69/70 seminoms and all 47 ITGCNs. Only 3/51 embryonal carcinomas (ECs) and 1/8 choriocarcinomas (in mononucleated trophoblasts) showed very focal weak TCL1 staining (1-5% tumor cells) whereas all spermatocytic seminomas, yolk sac tumors (YSTs), and teratomas were negative for TCL1. Normal seminferous tubules were negative for TCL1.
Conclusions: TCL1 overexpression is essentially limited to ITGCNs and seminomas. TCL1 dysregulation may play some role in the pathogenesis of ITGCNs and seminomas. TCL1 is a sensitive diagnostic marker for these 2 tumors (100% and 99%sensitivity, respectively).
Category: Genitourinary (including renal tumors)

Monday, March 22, 2010 1:00 PM

Poster Session II # 98, Monday Afternoon