Familial predisposition to Wilms' tumour does not map to the short arm of chromosome 11

Wilms' tumour of the kidney usually occurs sporadically, but can also segregate as an autosomal dominant trait with incomplete penetrance. Patients with the WAGR syndrome of aniridia, genitourinary anomalies, mental retardation and high risk of Wilms' tumour have overlapping deletions of chromosome 11p13 which has suggested a possible location for a Wilms' tumour locus. Moreover, many sporadic tumours have lost a portion of chromosome 11p. A second locus at 11p15 is implicated by association of the tumour with the Wiedemann-Beckwith syndrome and by tumour-specific losses of chromosome 11 confined to 11p15. Here we report a multipoint linkage analysis of a family segregating for Wilms' tumour, using polymorphic DNA markers mapped to chromosome 11p. The results exclude the predisposing mutation from both locations. In a second family, the 11p15 alleles lost in the tumour were derived from the affected parent, thus precluding this region as the location of the inherited mutation. These findings imply an aetiological heterogeneity for Wilms' tumour and raise questions concerning the general applicability of the carcinogenesis model that has been useful in the understanding of retinoblastoma.     

Development of homozygosity for chromosome 11p markers in Wilms' tumour

Somatic alterations in the genome are found in many human tumours. Chromosome rearrangements or base substitutions that activate cellular oncogenes appear to act dominantly. In contrast, recessive alleles apparently contribute to childhood retinoblastoma, as homozygosity (or hemizygosity ) for chromosome 13 is often established in tumours, by either mitotic nondisjunction or recombination. Parallels exist between retinoblastoma and childhood Wilms' tumour (WT). Retinoblastoma is often inherited and accompanied by a deletion of chromosome 13 (band q14), while WT is occasionally associated with aniridia and deletion of chromosome 11 band p13. Most Wilms' tumours are sporadic and not accompanied by these findings, although interstitial deletion of chromosome 11 in tumour, but not normal, cells has been reported. In view of these parallels, we compared constitutional and tumour DNAs from WT patients by using chromosome 11p DNA probes. We report here that although heterozygosity in constitutional DNAs was often preserved in tumour DNAs, one case developed homozygosity for chromosome 11p markers in tumour cells, implying the involvement of chromosomal events in revealing a recessive WT locus. This observation suggests the action of such general mechanisms in a tumour other than retinoblastoma.     

WT1 mutations contribute to abnormal genital system development and hereditary Wilms' tumour.

Wilms' tumour (WT), aniridia, genitourinary abnormalities and mental retardation form a symptom group (WAGR syndrome) associated with hemizygous deletions of DNA in chromosome band 11p13 (refs 1,2). However, it has not been clear whether hemizygosity at a single locus contributes to more than one phenotype. The tumour suppressor gene for Wilms' tumour, WT1, has been characterized: it is expressed at high levels in the glomeruli of the kidney, as well as the gonadal ridge of the developing gonad, the Sertoli cells of the testis and the epithelial and granulosa cells of the ovary, suggesting a developmental role in the genital system in addition to the kidney. We now report constitutional mutations within the WT1 genes of two individuals with a combination of WT and genital abnormalities as evidence of a role for a recessive oncogene in mammalian development.     

Lack of linkage of familial Wilms' tumour to chromosomal band 11p13

Wilms' tumour (WT), a paediatric renal neoplasm, affect approximately 1 in 10,000 children. One or both kidneys can be affected and 5-10% of tumours are bilateral. Most tumours occur sporadically; however, around 1% of the cases are familial, with siblings or cousins most often being affected. Familial cases are more frequently bilateral, and familial and bilateral tumours are diagnosed at an earlier age. On the basis of these observations, it was proposed that the development of WT requires two mutations. In most sporadic unilateral WT, both are somatic; in familial and bilateral tumours the first is thought to be germinal. Cytogenetic and molecular studies have demonstrated germinal mutations in WT/aniridia patients and somatic mutations in sporadic WT at chromosomal band 11p13. To investigate whether familial predisposition to WT is due to a germinal 11p13 mutation, we studied a WT family with seen DNA markers that span the 11p13 region. We found that familial WT predisposition was not genetically linked to any of the 11p13 markers. This suggests that the gene involved in familial WT predisposition is outside 11p13 and is distinct from the gene involved in tumorigensis and in WT predisposition in WT/aniridia 11p13-deletion patients.     

Somatic deletion and duplication of genes on chromosome 11 in Wilms' tumours

One of the most provocative findings in tumour biology is the relationship between chromosomal changes and embryonal cancers in children. For example, children with the rare paediatric syndrome AGR triad (aniridia, genito-urinary abnormalities and mental retardation) often develop Wilms' tumours at a very early age and carry a germ-line deletion on the short arm of chromosome 11 (11p13). It has been suggested that the germ-line deletion 11p is the first of two or more steps to cancer in AGR children. If this were true, one might expect a similar deletion to arise somatically in the far more common isolated Wilms' tumours of children without AGR, as suggested by Knudson from epidemiological data. However, a chromosomal deletion on 11p was observed in only two of five such cases, while it was absent or seen inconsistently in others. We have now used a molecular genetic approach to determine whether Wilms' tumour cells possess somatic alterations at 11p loci. We have found somatic deletions of specific genes in four of six Wilms' tumours. Surprisingly, in all four cases, the deletions were associated with duplications leading to homozygosity of the non-deleted alleles in the tumour cells. As analogous observations were recently reported in retinoblastoma, the genetic events reported here may underlie the development of many such embryonal tumours in children.     

Breakpoints in the human T-cell antigen receptor alpha-chain locus in two T-cell leukaemia patients with chromosomal translocations

Specific chromosomal translocations have been observed in several human and animal tumours and are believed to be important in tumorigenesis. In many of these translocations the breakpoints lie near cellular homologues of transforming genes, suggesting that tumour development is partly due to the activation of these genes. The best-characterized example of such a translocation occurs in mouse plasmacytoma and human B-cell lymphoma, where c-myc, the cellular homologue of the viral oncogene myc, is brought into close proximity with either the light- or heavy-chain genes of the immunoglobulin loci, resulting in a change in the regulation of the myc gene. T-cell malignancies also have characteristic chromosomal abnormalities, many of which seem to involve the 14q11-14q13 region. This region has recently been found to contain the alpha-chain genes of the human T-cell antigen receptor. Here we determine more precisely the chromosome breakpoints in two patients whose leukaemic T cells contain reciprocal translocations between 11p13 and 14q13. Segregation analysis of somatic cell hybrids demonstrates that in both patients the breakpoints occur between the variable (V) and constant (C) region genes of the T-cell receptor alpha-chain locus, resulting in the translocation of the C-region gene from chromosome 14 to chromosome 11. As the 11p13 locus has been implicated in the development of Wilms' tumour, it is possible that either the Wilms' tumour gene or a yet unidentified gene in this region is involved in tumorigenesis and is altered as a result of its translocation into the T-cell receptor alpha-chain locus.     

Insulin-like growth factor-II gene expression in Wilms' tumour and embryonic tissues

Wilms' tumour (nephroblastoma) is an embryonal neoplasm occurring in hereditary and spontaneous forms. Both types show rearrangements of the short arm of chromosome 11. The germ line of children with the rare inherited triad of aniridia, genito-urinary abnormality and mental retardation carry a chromosome 11 that has a deletion in its short arm (band 11p13) and these children are at increased risk of developing Wilms' tumour. Neonates with the Beckwith-Wiedemann syndrome, in which there may be duplication of the 11p13-11p15 region, are similarly predisposed. In the spontaneous form of the tumour a deletion of the 11p14 band in tumour cells, but not in normal cells, has been reported, and the development of homozygosity for recessive mutations in the 11p region is implicated in the aetiology of Wilms' tumour. In view of these chromosomal rearrangements and because Wilms' tumour is histologically indistinguishable from the early stages of kidney development, we have now examined the expression of genes localized to 11p in Wilms' tumour and human embryonic tissue. In 12 sporadic tumours examined, the expression of the gene coding for insulin-like growth factor-II (IGF-II), localized to the 11p15 region, was markedly increased relative to adult tissues, but was comparable to the level of expression in several fetal tissues including kidney, liver, adrenals and striated muscle. This may reflect the stage of tumour differentiation, but could also contribute to the malignant process, as IGF-II is an embryonal mitogen.     

c-Ha-ras1 is not deleted in aniridia-Wilms' tumour association

Non-random tumour-specific chromosomal abnormalities have been observed in cells of many different human tumours. In Wilms' tumour (WT) and retinoblastoma, a chromosomal deletion occurs germinally or somatically and has been considered an important step in tumour development. One class of potential cellular transforming genes comprises the cellular homologues of the transforming genes of highly oncogenic retroviruses. A remarkable concordance between the chromosomal location of human cellular oncogenes and the breakpoints involved in acquired chromosomal translocations is becoming apparent in various cancers: the oncogenes c-mos, c-myc and c-abl are located at the breakpoints that occur in acute myeloblastic leukaemia, Burkitt's lymphoma and chronic myelocytic leukaemia respectively. Thus when the oncogene c-Ha-ras1 was localized to the short arm of human chromosome 11 (refs 6-8; region 11p11 leads to p15 and not 11p13 as stated in ref. 5), it was proposed as a possible aetiological agent in the aniridia-WT association (AWTA) that results from a deletion of 11p13 (although a transforming gene recently isolated from a WT cell line (G401) was shown not to be homologous to either c-Ha-ras or c-Ki-ras9). We have now looked for deletion or rearrangement of c-Ha-ras1 in the DNA from four subjects with del(11p13)-associated predisposition to Wilms' tumour, aniridia, genitourinary abnormalities and mental retardation. We report here that in no case is c-Ha-ras1 deleted, and we have further refined its location to 11p15.1 leads to 11p15.5. On the basis of enzyme studies and direct gene dosage determination for c-Ha-ras1 and beta-globin in neoplastic and non-neoplastic tissues from one patient, we conclude that deletion of the normal counterpart of 11p cannot account for the development of the tumour.     

Loss of heterozygosity of chromosome 3p markers in small-cell lung cancer

Specific chromosomal deletions sometimes associated with tumours such as retinoblastoma (chromosome 13q14) and Wilm's tumour (chromosome 11p13) have led to the hypothesis that recessive genes may be involved in tumorigenesis. This hypothesis is supported by demonstration of allele loss specific for these regions using polymorphic DNA markers and by the isolation of a complementary DNA clone for the retinoblastoma gene. A cytogenetic deletion in chromosome 3 (p14-p23) was reported in small-cell lung cancer (SCLC) by Whang-Peng et al. At least one homologue of chromosome 3 was affected in the majority of SCLC tumours; however, the multiple chromosomal changes seen presented the possibility that chromosome 3 was rearranged, not deleted. We used polymorphic DNA probes for chromosome 3p and compared tumour and constitutional genotypes of nine SCLC patients. Our data show loss of alleles of chromosome 3p markers in tumour DNA of all nine patients supporting the hypothesis that this region contributes to tumorigenesis in SCLC.     

Loss of a Harvey ras allele in sporadic Wilms' tumour

Genomic changes within chromosome band 11p13 appear to have a role in the initiation of Wilms' tumour. The human Harvey ras oncogene, c-Ha-ras 1, has been located by Jhanwar et al. immediately adjacent to this region at band 11p14 .1, although several groups have assigned the gene more distally at band 11p15 . We have examined tumour DNA from two cases of sporadic Wilms' tumour, and report here that in both cases one of the two constitutional c-Ha-ras 1 alleles was absent. One tumour had a reciprocal translocation between the short arm of chromosome 11 (at band 11p13), and the long arm of chromosome 12, with no visible loss of chromosomal material. The loss of a c-Ha-ras 1 allele in association with this translocation indicates that a submicroscopic deletion had occurred. The resulting hemizygosity may have had a role in tumour initiation. Our results indicate that the c-Ha-ras 1 gene and the 'Wilms' tumour locus' may be in close proximity. It would, therefore, be premature to exclude the possibility that these two sites are functionally related.     

Loss of constitutional heterozygosity in colon carcinoma from patients with familial polyposis coli

Recent studies have suggested a critical role of specific gene loss in several embryonic tumours and certain adult cancers. In retinoblastoma, hemizygosity or homozygosity of a recessive mutant allele results in the loss of normal gene product, and this seems to cause the manifestation of the disorder. Familial polyposis coli (FPC) is a human autosomal dominant trait characterized by numerous adenomatous polyps of the colon and rectum, and a high incidence of colon carcinoma. Karyotype analyses have failed to detect specific deletion or translocation. We report the use of polymorphic DNA markers to look for the somatic loss of heterozygosity at specific loci. Investigation of 38 tumours from 25 FPC patients, and 20 sporadic colon carcinomas from 19 patients, revealed frequent occurrence of allele loss on chromosome 22, with some additional losses on chromosomes 5, 6, 12q and 15. The FPC gene-linked DNA probe C11p11 also detected frequent allele loss in both familial and sporadic colon carcinomas but not in benign adenomas. These results suggest the possible involvement of more than one chromosomal locus in the development of familial and sporadic colon carcinomas.     

Uniparental paternal disomy in a genetic cancer-predisposing syndrome.

The 11p15.5 region of human chromosome 11 seems to contain a locus or loci involved in congenital overgrowth anomalies as well as in the genesis of many tumours associated with the Beckwith-Wiedemann syndrome (BWS). Given the unusual differential parental allele involvement in the different aetiological forms of BWS and the loss of maternal alleles in associated tumours, we have now used 11p15.5 markers to determine the parental origin of chromosome 11 in eight sporadic cases of BWS. Probands in three informative families had uniparental paternal disomy for region 11p15.5. Further, an overall greatly increased frequency of homozygosity for several 11p15.5 markers in 21 sporadic BWS patients suggests that isodisomy probably accounts for an even higher proportion of BWS sporadic cases. This demonstrates that uniparental paternal disomy can be associated with a genetic cancer-predisposing syndrome.     

Loss of genes on the short arm of chromosome 11 in bladder cancer

Recent studies have shown that normal cellular sequences on chromosome 13 are lost during the development of retinoblastomas and that sequences on chromosome 11 are similarly lost during the development of Wilms' kidney tumours and embryonal tumours. Cells from these tumors have been found to contain either the paternal or maternal copies of loci on the affected chromosome, but not both. Thus, the somatic loss of heterozygosity for sequences on chromosome 13 or 11 is hypothesized to result in homozygosity for a recessive mutant allele on these chromosomes, and in this way the chromosomal loss may contribute to the development of these tumours. We sought to investigate whether similar losses of heterozygosity for chromosome 11 sequences occurred in a common adult tumour. We chose to analyse bladder cancers, since such cancers are common in the adult population and are derived from urogenital tissue, as are Wilms' tumours. We examined constitutional and tumour genotypes at loci on the short arm of chromosome 11 (11p) in 12 patients with transitional cell carcinomas. In five tumours, we observed the somatic loss of genes on 11p resulting in homozygosity or hemizygosity of the non-deleted alleles in the tumour cells. Our results show that the frequency of loss of 11p sequences in bladder cancer approaches that seen in Wilms' tumour (42% compared with 55%), and suggest that recessive genetic changes involving sequences on 11p may contribute to the development of bladder neoplasms.     

GLI3 zinc-finger gene interrupted by translocations in Greig syndrome families.

The Greig cephalopolysyndactyly syndrome (GCPS) is an autosomal dominant disorder affecting limb and craniofacial development in humans. GCPS-affected individuals are characterized by postaxial polysyndactyly of hands, preaxial polysyndactyly of feet, macroephaly, a broad base of the nose with mild hypertelorism and a prominent forehead. The genetic locus has been pinpointed to chromosome 7p13 by three balanced translocations associated with GCPS in different families. This assignment is corroborated by the detection of two sporadic GCPS cases carrying overlapping deletions in 7p13 (ref. 7), as well as by tight linkage of GCPS to the epidermal growth factor receptor gene in 7p12-13 (ref. 8). Of the genes that map to this region, those encoding T cell receptor-gamma, interferon-beta 2, epidermal growth factor receptor, and Hox1.4, a potential candidate gene for GCPS, have been excluded from the region in which the deletions overlap. Here we show that two of the three translocations interup the GLI3 gene, a zinc-finger gene of the GLI-Krüppel family already localized to 7p13 (refs 5, 6). The breakpoints are within the first third of the coding sequence. In the third translocation, chromosome 7 is broken at about 10 kilobases downstream of the 3' end of GLI3. Our results indicate that mutations disturbing normal GLI3 expression may have a causative role in GCPS.     

Mutations in the p53 gene occur in diverse human tumour types

The p53 gene has been a constant source of fascination since its discovery nearly a decade ago. Originally considered to be an oncogene, several convergent lines of research have indicated that the wild-type gene product actually functions as a tumour suppressor gene. For example, expression of the neoplastic phenotype is inhibited, rather than promoted, when rat cells are transfected with the murine wild-type p53 gene together with mutant p53 genes and/or other oncogenes. Moreover, in human tumours, the short arm of chromosome 17 is often deleted. In colorectal cancers, the smallest common region of deletion is centred at 17p13.1; this region harbours the p53 gene, and in two tumours examined in detail, the remaining (non-deleted) p53 alleles were found to contain mutations. This result was provocative because allelic deletion coupled with mutation of the remaining allele is a theoretical hallmark of tumour-suppressor genes. In the present report, we have attempted to determine the generality of this observation; that is, whether tumours with allelic deletions of chromosome 17p contain mutant p53 genes in the allele that is retained. Our results suggest that (1) most tumours with such allelic deletions contain p53 point mutations resulting in amino-acid substitutions, (2) such mutations are not confined to tumours with allelic deletion, but also occur in at least some tumours that have retained both parental 17p alleles, and (3) p53 gene mutations are clustered in four 'hot-spots' which exactly coincide with the four most highly conserved regions of the gene. These results suggest that p53 mutations play a role in the development of many common human malignancies.     

Variant (6 ; 15) translocation in a murine plasmacytoma occurs near an immunoglobulin kappa gene but far from the myc oncogene

Chromosome translocations in B-lymphoid tumours are providing intriguing insights and puzzles regarding the role of immunoglobulin genes in the activation of the myc oncogene (reviewed in refs 1, 2). The 15 ; 12 translocations found in most murine plasmacytomas and the analogous 8 ; 14 translocation in human Burkitt's lymphomas involve scissions of murine chromosome 15 (human chromosome 8) near the 5' end of the c-myc gene and subsequent fusion near an immunoglobulin heavy-chain gene. The less well characterized 'variant' translocations found in about 15% of such tumours also involve the myc-bearing chromosome band, but exchange occurs with a chromosome bearing an immunoglobulin light-chain locus--in mice, the kappa-chain locus bearing chromosome 6 (refs 3-5) and, in man, chromosome 2 (or 22), at the same band at which the kappa (or lambda) locus lies (reviewed in ref. 1). The Burkitt variant translocations involve scissions 3' of c-myc; one 8 ; 22 translocation placed the C lambda locus just 3' of c-myc, but usually the chromosome 8 breakpoint is a greater, but unknown, distance away from c-myc, more than 20 kilobases (kb) in one 8 ; 2 translocation involving the C kappa gene. Little is known about the murine 6 ; 15 translocations, although a C kappa gene cloned from one plasmacytoma (PC7183) is linked, via chromosome 12 sequences, to an unidentified region of chromosome 15 (ref. 11). We describe here the chromosome fusion region from plasmacytoma ABPC4, which displays the typical reciprocal 6;15 translocations. We find that the chromosome 6 breakpoint is near C kappa but, unlike those in the heavy-chain locus, not at a position where immunoglobulin genes normally recombine. Moreover, the chromosome 15 sequences involved in the ABPC4 translocation are not derived from the vicinity of c-myc.     

Clustering of breakpoints on chromosome 11 in human B-cell neoplasms with the t(11;14) chromosome translocation

The t(11;14) (q13;q32) chromosome translocation has been reported in diffuse small and large cell lymphomas and in chronic lymphocytic leukaemia (B-CLL) and multiple myeloma. Because chromosome band 14q32 is involved in this translocation, as well as in the t(8;14) (q24;q32) translocation of the Burkitt tumour, interruption of the immunoglobulin heavy-chain locus was postulated for this rearrangement. We have cloned the chromosomal joinings between chromosomes 11 and 14 and also between chromosomes 14 and 18, in B-cell tumours carrying translocations involving these chromosomes, and suggested the existence of two translocated loci, bcl-1 and bcl-2, normally located on chromosomes 11 (band q13) and 18 (band q21) respectively, involved in the pathogenesis of human B-cell neoplasms. The results indicate that in the leukaemic cells from two different cases of CLL, the breakpoints on chromosome 11 are within 8 nucleotides of each other and on chromosome 14 involve the J4-DNA segment. Because we detected a 7mer-9mer signal-like sequence with a 12-base-long spacer on the normal chromosome 11, close to the breakpoint, we speculate that the t(11;14) chromosome translocation in CLL may be sequence specific and may involve the recombination system for immunoglobulin gene segment (V-D-J) joining.