Sw. Faulkner et al., Allelic losses in carcinoma in situ and testicular germ cell tumours of adolescents and adults: evidence suggestive of the linear progression model, BR J CANC, 83(6), 2000, pp. 729-736
Testicular germ cell tumours (TGCTs) may arise through a process of multi-s
tep carcinogenesis, and loss of heterozygosity (LOH) at specific loci is li
kely to be an important early event, although this has not been studied in
detail. In order to explore the pathogenetic relationships among TGCTs, we
investigated the genetic changes in testicular tumours that exhibit a disea
se continuum through the precursor carcinoma in situ (CIS) to either semino
ma (SE) and/or non-seminomatous germ cell tumour (NSGCT). Universal amplifi
cation has been performed on 87 TGCT specimens and 36 samples of CIS cells
microdissected from single paraffin-embedded tumour sections from 40 patien
ts, including multiple specimens of CIS and TGCT cells of varied histology
microdissected from 24 individual patients. Seventy-seven microsatellite ma
rkers were used to assay these samples for LOH at candidate regions selecte
d from the literature, mapping to 3q, 5q, 9p, 11p, 11q, 120, 17p and 18q, C
onstruction of deletion maps for each of these regions identified common si
tes of deletion at 3q27-q28, 5q31, 5q34-q35, 9p22-p21 and 12q22, which corr
elate with allelic losses we have also observed in the precursor CIS cells.
Evidence for allelic loss at 3q27-q28 was observed in all of the embryonal
carcinoma samples analysed. We conclude that inactivation of gene(s) withi
n these regions are likely to be early events in the development and progre
ssion of TGCTs. These results also provide molecular evidence in support of
the hypothesis that SE is an intermediate stage of development within a si
ngle neoplastic pathway of progression from CIS precursor cells to NSGCT. (
CT) 2000 Cancer Research Campaign.