5 research outputs found
Detection of human endogenous retrovirus type K-specific transcripts in testicular parenchyma and testicular germ cell tumors of adolescents and adults: clinical and biological implications
Testicular germ cell tumors (TGCTs) of adolescents and adults have been
shown to contain proteins of the human endogenous retrovirus type K
family. In a recent study, expression of these retroviral sequences was
confirmed using in situ hybridization, which also showed expression in
carcinoma in situ, the precursor of all TGCTs. Because of the clinical
significance of a test for early diagnosis of TGCTs, we studied whether
expression of human endogenous retrovirus type K genes could be an
informative parameter. Therefore, we investigated TGCTs of various
histologies and testicular parenchyma with and without carcinoma in situ
using reverse transcription-polymerase chain reaction for expression of
the gag, env, and prt genes. The gag and prt genes were expressed in all
samples tested. The env transcripts were not found in TGCTs showing
somatic differentiation only but could be detected in most normal
testicular parenchyma samples. Therefore, detection of human endogenous
retrovirus type K transcripts cannot be used for early diagnosis of TGCTs.
Simultaneous expression of multiple gag sequences was found both in normal
parenchyma and TGCTs, and we demonstrated that expression of gag sequences
with an extra G, necessary to generate a functional protein, was not
limited to TGCTs
Coamplification of DAD-R, SOX5, and EKI1 in human testicular seminomas, with specific overexpression of DAD-R, correlates with reduced levels of apoptosis and earlier clinical manifestation
Seminomas and nonseminomas represent the invasive stages of testicular
(TGCTs) of adolescents and adults. Although TGCTs are characterized by
extra copies of the short arm of chromosome 12, the genetic basis for gain
of 12p in the pathogenesis of this cancer is not yet understood. We have
demonstrated that gain of 12p is related to invasive growth and that
amplification of specific 12p sequences, i.e., 12p11.2-p12.1, correlates
with reduced apoptosis in the tumors. Here we show that three known genes
map within the newly determined shortest region of overlap of
amplification (SROA): DAD-R, SOX5, and EKI1. Whereas EKI1 maps close to
the telomeric region of the SROA, DAD-R is the first gene at the
centromeric region within the 12p amplicon. Although all three genes are
amplified to the same level within the SROA, expression of DAD-R is
significantly up-regulated in seminomas with the restricted 12p
amplification compared with seminomas without this amplicon. DAD-R is also
highly expressed in nonseminomas of various histologies and derived cell
lines, both lacking such amplification. This finding is of particular
interest because seminomas with the restricted 12p amplification and
nonseminomas are manifested clinically in the third decade of life and
show a low degree of apoptosis. In contrast, seminomas lacking a
restricted 12p amplification, showing significantly lower levels of DAD-R
with pronounced apoptosis, manifest clinically in the fourth decade of
life. A low level of DAD-R expression is also observed in normal
testicular parenchyma and in parenchyma containing the precursor cells of
this cancer, i.e., carcinoma in situ. Therefore, elevated DAD-R expression
in seminomas and nonseminomas correlates with invasive growth and a
reduced level of apoptosis associated with an earlier clinical
presentation. These data implicate DAD-R as a candidate gene responsible
in part for the pathological effects resulting from gain of 12p sequences
in TGCTs. In addition, our results also imply differences in expression
regulation of DAD-R between seminomas and nonseminomas
Restricted 12p amplification and RAS mutation in human germ cell tumors of the adult testis
Human testicular germ-cell tumors of young adults (TGCTs), both seminomas
and nonseminomas, are characterized by 12p overrepresentation, mostly as
isochromosomes, of which the biological and clinical significance is still
unclear. A limited number of TGCTs has been identified with an additional
high-level amplification of a restricted region of 12p including the K-RAS
proto-oncogene. Here we show that the incidence of these restricted 12p
amplifications is approximately 8% in primary TGCTs. Within a single cell
formation of i(12p) and restricted 12p amplification is mutually
exclusive. The borders of the amplicons cluster in short regions, and the
amplicon was never found in the adjacent carcinoma in situ cells.
Seminomas with the restricted 12p amplification virtually lacked apoptosis
and the tumor cells showed prolonged in vitro survival like seminoma cells
with a mutated RAS gene. However, no differences in proliferation index
between these different groups of seminomas were found. Although patients
with a seminoma containing a homogeneous restricted 12p amplification
presented at a significantly younger age than those lacking it, the
presence of a restricted 12p amplification/RAS mutation did not predict
the stage of the disease at clinical presentation and the treatment
response of primary seminomas. In 55 primary and metastatic tumors from 44
different patients who failed cisplatinum-based chemotherapy, the
restricted 12p amplification and RAS mutations had the same incidence a
Stem cell factor receptor (c-KIT) codon 816 mutations predict development of bilateral testicular germ-cell tumors
Testicular germ-cell tumors (TGCTs) of adolescents and adults originate
from intratubular germ cell neoplasia (ITGCN), which is composed of the
malignant counterparts of embryonal germ cells. ITGCN cells are
characterized, among others, by the presence of stem cell factor receptor
c-KIT. Once established, ITGCN will always progress to invasiveness.
Approximately 2.5-5% of patients with a TGCT will develop bilateral
disease and require complete castration, resulting in infertility, a need
for lifelong androgen replacement, and psychological stress. To date, the
only way to predict a contralateral tumor is surgical biopsy of the
contralateral testis to demonstrate ITGCN. We did a retrospective study of
224 unilateral and 61 proven bilateral TGCTs (from 46 patients, in three
independently collected series in Europe) for the presence of activating
c-KIT codon 816 mutations. A c-KIT codon 816 mutation was found in three
unilateral TGCT (1.3%), and in 57 bilateral TGCTs (93%; P < 0.0001). In
the two wild-type bilateral tumors for which ITGCN was available, the
preinvasive cells contained the mutation. The mutations were somatic in
origin and identical in both tumors. We conclude that somatic activating
codon 816 c-KIT mutations are associated with development of bilateral
TGCT. Detection of c-KIT codon 816 mutations in unilateral TGCT identifies
patients at risk for bilateral disease. These patients may undergo
tailored treatment to prevent the development of bilateral disease, with
retention of testicular hormonal function