Glypican 3: A Novel Marker in
Testicular
Germ Cell Tumors
Debra L. Zynger,MD,* Nikolay D. Dimov,MD,* Chunyan Luan,MS,* Bin Tean
Teh,MD, PhD,w
and Ximing J. Yang, MD, PhD*
From the *Department of Pathology, Feinberg School of Medicine,
Northwestern University, Chicago, IL; and Laboratory of Cancer
Genetics, Van Andel Research Institute
American Journal of Surgical Pathology 2006;30:1570–1575
指導老師: 方嘉郎醫師
Intern 林培豐
Introduction-1
 Glypicans(GPC)
A family of heparin sulfate proteoglycans.
6 members in mouse and human.
Extracellular proteins bound to the cell surface
by a glycophosphatidylinositol anchor
 glypican 3(GPC3)
Regulate growth through interactions with
morphogenic or growth factorsWnt5a,
fibroblast growth factor 2, bone morphogenic
protein 7, and tissue factor pathway inhibitor
Introduction-2
Normally expressed in trophoblasts and fetal
tissues
Limited expression in adult tissues: ovary,
breast, lung, and mesothelium
 Mammary carcinoma, ovarian carcinoma, lung
adenocarcinoma, and malignant mesothelioma
GPC3 mRNA level ↓
Mutations Simpson-Golabi-Behmel (SGB)
syndrome, a rare X-linked overgrowth syndrome
characterized by numerous craniofacial, skeletal,
and genitourinary abnormalities.
Introduction-3
Maybe an oncofetal protein
GPC3 mRNA level↑hepatocellular carcinoma,
hepatoblastoma, Wilms tumor, neuroblastoma,
rhabdomyosarcoma, Wilms tumor,
hepatocellular carcinoma, and hepatoblastoma.
Testicular germ cell tumors
 Common cell of origin, but differ with degree
of differentiation.
MATERIALS-1
 71 primary testicular germ cell tumors
between 1996 and 2005 were obtained from
Northwestern Memorial Hospital
 46 mixed tumors; 25 pure seminomas
MATERIALS-2
 Mixed tumors: 17 to 60 years (mean=30.9 y)
 The mixed germ cell tumors
 37stage I
 5stage II
 4stage III
 Pure seminomas：24 to 55 years (mean=35.6 y).
 24 stage I
 1 stage III
 Benign testicular tissues from 58 cases  negative control
 Immature and mature placental tissues positive control
METHONDS
 Sections (5 mm) from 1 to 3 representative blocks
deparaffinized, rehydrated in graded alcohols, and
epitope retrieval in 0.1M citrate buffer at pH 6.0 in
a microwave for 20 minutes
 Primary monoclonal antibody of 1:200 for 1 hour at
room temperature
 Rabbit antimouse secondary antibody
 semiquantitatively evaluated as
negative (0, <5% of cells stained)
focally positive (1+, 5% to 10% of cells stained)
positive (2+, 11% to 50% of cells stained)
diffusely positive (3+, >50% of cells stained
RESULTS-1
 Positive control :
strong GPC3 (+) in syncytiotrophoblasts;
weaker staining in cytotrophoblasts.
 Negative control
germ cells, Sertoli cells, Leydig cells, blood
vessels, fibroblasts, and hematopoietic cells,
intratubular germ cell neoplasia  GPC(-)
RESULTS-2
 Yolk sac tumor hematoxylin and eosin (H&E)
and diffuse, strong GPC3 immunoreactivity.
C: GPC3 immunostaining, Yolk sac tumor and Embryonal
carcinoma
D, GPC3 immunostaining, yolk sac tumor and teratoma
with mature elements
 E and F, Choriocarcinoma H&E and GPC3 immunostaining
showing strong immunoreactivity in syncytiotrophoblasts
and weaker staining in cytotrophoblasts.
 A and B, Teratoma with immature neuroectodermal
elements H&E and GPC3 immunostaining
showing strong immunoreactivity.
 C and D, Teratoma with mature squamous
epithelium H&E and negative GPC3.
E and F, Embryonal carcinoma H&E and
GPC3 immunostaining without reactivity or
background.
 G and H, Embryonal carcinoma H&E and GPC3
immunostaining demonstrating weak, focal positivity
 Peripheral teratoma: mature glandular epithelium, GPC3(-)
 Seminoma
DISCUSSION-1
 Previously reported by Sugimura et al
Testicular germ cell tumors revealed
differential expression of a large number of
genes.
 GPC3: 3rd most overexpressed gene in yolk
sac tumors
mRNA level 4.2-fold ↑ comparing other
non-seminoma
 embryonal carcinoma 10-fold ↓
DISCUSSION-2
 In current studies
 GPC3 expression (+): yolk sac tumor, choriocarcinoma
 GPC3 expression(-): non-neoplastic testicular
parenchyma, intratubular germ cell neoplasia,
seminomas, teratomas with mature elements, and the
majority of embryonal carcinomas and teratomas
with immature elements
 In this study diagnostic value in identifying yolk
sac tumor from other germ cell tumor subtypes
DISCUSSION-3
 GPC3 mutations  SGB syndrome
in prenatal and postnatal overgrowth correlated with
GPC3-deficient mice models
 GPC3 widely expressed in fetal tissues, esp. in liver, lung,
kidney and placental tissues
 In adult, GPC3 expression is restricted in the epithelium of
breast, ovary, lung, and mesothelium
 In mammary carcinoma, ovarian carcinoma, lung
adenocarcinoma, and malignant mesothelioma, GPC3
expression was reduced or silenced
 GPC3: negative regular of growth and tissue-specific
tumor supressor activity
 Loss of function or reduced expression contribute to
the malignant phenotype of certain tumors.
DISCUSSION-4
 10% cases of SGB syndromes acquire a
malignancy, including neuroblastoma,
gonadoblastoma, Wilms tumor, hepatoblastoma,
or hepatocellular carcinoma.
 Sporadic forms of these tumor have increased
GPC3 expression
 GPC3 conversely acted as oncofetal protein
GPC3 is a growth inhibitor or oncofetal protein
depending upon the tissue
Discussion-5
 Interestingly, the expression of GPC3 in other
embryonal tumors varies
 Rhabdomyosarcoma: GPC 3 protein(+)
 But Ewing sarcoma or medulloblastoma: GPC3 protein(-
)
 UnclearGPC3 expression
↑ plays a critical role
in tumor development
 Perhaps GPC3 is expressed in tumors with a
certain level of fetal differentiation, but is negative
in poorly differentiated embryonal malignancies.
 GPC3 may play a role in lineage or stage specific
germ cell tumor differentiation.
Discussion-6
 Yolk sac tumor：most frequently overlooked and
close association with embryonal carcinoma
clinical significance in metastasis, recurrence
 GPC3 immunostaining makes it easy to
distinguish, whereas more than 90% of embryonal
carcinomas were negative.
 α-FP(+) in 74~100% of yolk sac tumors and
0% ~33% of embryonal carcinomas.
 Further experiments are needed to compare the
sensitivity and specificity of GPC3 and α-FP in
yolk sac tumor.
Discussion-7
 Certain patterns of yolk sac tumor may seem
similar to seminoma.
 This study revealed that all seminomatous components
and intratubular germ cell neoplasia were GPC(-)
 Future studiessensitivity and specificity of GPC3
in distinguishing yolk sac tumor from seminoma in
comparison with other markers such as OCT4, ckit, keratin, placental alkaline phosphatase, and αFP
Discussion-8
 Choriocarcinoma：GPC3 exhibited a similar
pattern as β-HCG
 more intense staining in syncytiotrophoblasts than in
cytotrophoblasts.
 Serum test for GPC3 in non-seminoma germ cell
tumors
 Recent studies, GPC3 more sensitive and specific
serum marker for hepatocellular carcinoma than
α-FP
 Potential therapeutic target
CONCLUSION
 GPC3 is a novel marker in all yolk sac tumors and
choriocarcinomas, but not in seminomas,
teratomas with mature elements, and the majority
of embryonal carcinomas and teratomas with
immature elements.
 This study not only suggests a possible role of
GPC3 in germ cell tumor lineage-specific
differentiation, but also provides evidence for a
new promising diagnostic marker of testicular
germ cell tumors.