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Two mutations of the ATM gene were recently suggested to confer breast cancer risks similar to mutations of BRCA1 or BRCA2. Here, we set out to confirm these findings in 961 families with non-BRCA1/BRCA2 breast cancer from diverse geographical regions. We did not detect the ATM 7271T-->G mutation in any family. The ATM IVS10-6T-->G mutation was detected in eight families, which was similar to its frequency among population-matched control individuals (pooled Mantel-Haenszel odds ratio = 1.60; 95% confidence interval = 0.48 to 5.35; P = 0.44). Bayesian analysis of linkage in the ATM IVS10-6T-->G-positive families showed an overall posterior probability of causality for this mutation of 0.008. We conclude that the ATM IVS10-6T-->G mutation does not confer a significantly elevated breast cancer risk and that ATM 7271T-->G is a rare event in familial breast cancer.

Background: Using array analysis for screening RNA from BRCA1-mutated and sporadic breast tumors, we observed that AIGF/FGF-8 expression was lost in BRCA1-mutated breast tumors. Since this growth factor is induced by androgens, we studied the androgen receptor (AR) expression in BRCA-mutated tumors and in matched sporadic breast tumors., Methods: Paraffin embedded breast tumors of carriers of a BRCA1 mutation (n=41, median age of patients at time of surgery was 41 years [range 28-59 years]) or a BRCA2 mutation (n=14, median age 41 years [range 31-85 years]) were analyzed for the presence of ER-alpha, PR, P53 and AR using standard immunohistochemical techniques. All statistical tests used, Pearson chi2 and Fisher exact, were two-sided., Results: The AR was only present in 12% of BRCA1-mutated tumors, with mutations located at the C-terminal half of the BRCA1-gene. The AR expression was significantly more prevalent, however, in a series of 61 sporadic breast tumors (80%) and in BRCA2-mutated tumors (50%). In contrast to an increased percentage of p53 positive cells, in 66% of the BRCA1-mutated tumors, the ER-alpha expression was observed only in 25% and the PR in 13% of these specimens. The three steroid hormone receptors were expressed in about half of the BRCA2-mutated specimens studied., Conclusions: Our data add to the emerging evidence that the biological phenotype of BRCA1-associated tumors may be different from BRCA2 and non-hereditary cases. The loss of the AR expression, as shown by immunohistochemistry, together with the observed loss of other steroid hormone receptors in BRCA1-mutated tumors may lead to a hormone-independent growth or to anti-hormone resistant growth of these tumors.

Fibroblast growth factors (FGFs) comprise a family of 22 distinct proteins with pleiotropic signaling functions in development and homeostasis. These functions are mediated principally by four fibroblast growth factor receptors (FGFRs), members of the receptor tyrosine kinase family, with heparin glycosaminoglycan as an important cofactor. Developmental studies in chick and mouse highlight the critical role of FGF-receptor signaling in multiple phases of limb development, including the positioning of the limb buds, the maintenance of limb bud outgrowth, the detailed patterning of the limb elements, and the growth of the long bones. Corroborating these important roles, mutations of two members of the FGFR family (FGFR1 and FGFR2) are associated with human disorders of limb patterning; in addition, mutations of FGFR3 and FGF23 affect growth of the limb bones. Analysis of FGFR2 mutations in particular reveals a complex pattern of genotype/phenotype correlation, which will be reviewed in detail. Circumstantial evidence suggests that the more severe patterning abnormalities are mediated by illegitimate paracrine signaling in the mesoderm, mediated by FGF10 or by a related FGF, and this is beginning to gain some experimental support. A further test of this hypothesis is provided by a unique family segregating two FGFR2 mutations in cis (S252L; A315S), in which severe syndactyly occurs in the absence of the craniosynostosis that typically accompanies FGFR2 mutations., (Copyright 2002 Wiley-Liss, Inc.)

Several germ cell tumors that occur in adult men likely originate from gonocytes that are impaired in their development. To select candidate genes that are involved in the normal development of the gonocytes, we constructed a complementary DNA (cDNA) library from rat gonocytes as well as from single, paired, and aligned A spermatogonia (A(s), A(pr), and A(all) spermatogonia, respectively), their direct descendants. Five hundred gonocyte clones were differentially screened using both libraries. Successive verification by dot blot assays yielded 7 clones that were consistently highly abundant only in the gonocyte cDNA library. Also, in situ hybridization of these clones confirmed their differential expression. They encoded for, respectively, succinate dehydrogenase, ribosomal protein S15a, and the 65-kilodalton scaffolding subunit (a isoform) of protein phosphatase 2A. No clues regarding the nature of the remaining four clones could be found. Hence, using differential screening on both constructed cDNA libraries, we were able to select several genes that are interesting candidates for studying the molecular mechanisms of normal gonocyte development.

Spermatogonial cell lines were established by transfecting a mixed population of purified rat A(s) (stem cells), A(pr) and A(al) spermatogonia with SV40 large T antigen. Two cell lines were characterized and found to express Hsp90alpha and oct-4, specific markers for germ cells and A spermatogonia, respectively. Expression of c-kit, normally expressed in A spermatogonia from late A(al) spermatogonia onwards, could not be detected in either cell line. Furthermore, no expression of vimentin (Sertoli cell marker) and alpha-smooth muscle actin (peritubular cell marker) could be found. Upon transplantation of these cell lines into recipient mice, the cells were found to be able to migrate to the basement membrane and to colonize seminiferous tubules. Taken together, we conclude that our cell lines have spermatogonial stem cell characteristics. These first spermatogonial cell lines with stem cell characteristics can now be used to study spermatogonial gene expression in comparison with more advanced germ cells.