Loss Of Chromosome 19q Research Articles

703 Loss of chromosome 14Q is a stronf predictor of progression in conventional renal cell carcinoma

703 Loss of chromosome 14Q is a stronf predictor of progression in conventional renal cell carcinoma

Loss of chromosome 18q and DPC4 (Smad4) mutations in appendiceal adenocarcinomas.

Appendiceal adenocarcinomas are uncommon, and the genetic alterations present in these tumors are not well characterized. We studied genetic alterations including loss of chromosome 18q (location of DCC, DPC4, and JV-18 genes), and mutations of the DPC4 (SMAD4) and beta-catenin genes in 28 appendiceal adenocarcinomas, consisting of 17 mucinous and 11 nonmucinous carcinomas. Chromosome 18q loss was present in 57% (12/21) of appendiceal carcinomas including 54% (7/13) of mucinous and 63% (5/8) of nonmucinous carcinomas. Mutation of the DPC4 gene was present in 14% (three of 22) of the carcinomas occurring in one tumor with chromosome 18q loss and in two with unassessed chromosome 18q status. beta-catenin gene mutation was present in 0% (0 of 25) of the carcinomas. Chromosome 18q loss status was not associated with any clinicopathological features. The presence of chromosome 18q loss and DPC4 mutations in appendiceal adenocarcinomas suggests involvement of DPC4 and nearby genes on chromosome 18q (DCC and/or JV-18) in the pathogenesis of appendiceal adenocarcinomas.

Paternal age over 40 years: the "amber light" in the reproductive life of men?

In industrialized countries, many couples are choosing to delay childbearing, and the proportion of couples having children after age 30–35 years has increased. This has highlighted the effect of age on reproductive failure (van Balen et al, 1997). The effects of maternal age have been thoroughly investigated in the past few decades, and a major effect of maternal age over 35 years has been demonstrated on infertility, ectopic pregnancy, and miscarriage (van Noord-Zaadstra et al, 1991; van Balen et al, 1997; Nybo Andersen et al, 2000). In contrast, little attention has been paid to the possible effects of paternal age. Most studies that have dealt with this factor have focused on changes in sperm characteristics with age, and physicians have tried to set an upper age limit for sperm donors. The American Society for Reproductive Medicine (1998) and the British Andrology Society (1999) have fixed the upper age limit for sperm donation at 40 years old on the basis of the increased risk of genetic abnormalities in children of older fathers (Bordson and Leonardo, 1991). In discussions of the effects of paternal age with a view toward setting age limits for sperm donors, the possibility that paternal age affects the likelihood of reproductive failure was not considered. In other respects, some demographic studies have analyzed the effects of paternal age on effective fecundity, which is the probability of initiating a pregnancy leading to a live birth (Anderson, 1975; Mineau and Trussell, 1982; Goldman and Montgomery, 1989; Strassmann and Warner, 1998). These studies, based on large data sets from populations not using birth control methods, showed

PTEN/MMAC1 gene mutation is a rare event in soft tissue sarcomas without specific balanced translocations.

The tumor suppressor gene PTEN/MMAC1 was identified on chromosome 10q23.3, which is homozygously deleted in many human malignancies. The loss of chromosome 10q was also frequently reported in some types of soft tissue sarcomas. Our study was designed to investigate the frequency of PTEN/MMAC1 gene mutation and to evaluate the role of the PTEN/MMAC1 gene in the tumorigenesis of soft tissue sarcomas without specific balanced translocations. We analyzed 51 cases of soft tissue sarcomas without specific balanced translocations for PTEN/MMAC1 mutations by polymerase chain reaction-single strand conformation polymorphism and direct sequencing. Mutations in the PTEN/MMAC1 gene were found in only 2 cases (3.9%). Both tumors with PTEN/MMAC1 mutation were leiomyosarcomas arising from the retroperitoneum and inferior vena cava, respectively. Two of 3 leiomyosarcomas arising from the intra-abdominal cavity examined harbored mutations of this tumor suppressor gene. This result suggests that leiomyosarcomas derived from the intra-abdominal cavity might have different tumorigenesis from those of an extremity or the trunk, from the viewpoint of PTEN/MMAC1 mutation, although PTEN/MMAC1 gene mutations are rare event in these soft tissue sarcomas.

Diagnostic molecular genetics and its application to clinical decision in brain tumors

The authors review new insights into molecular genetics-based diagnosis and show the applications to clinical decisions we are conducting in some types of brain tumors. Among the many genetic alterations noted in astrocytic tumors, the methylation status of a DNA repair enzyme, O 6-methyl-guanine-DNA methyltransferase (MGMT), is now in the limelight. It has been reported that the methylation status of MGMT determines its response to alkylating agents. Our target for molecular diagnosis within gliomas is the oligodendroglial tumor. We conducted cytogenetic and LOH analysis of 14 oligodendroglial tumors using fluorescent in situ hybridization (FISH) and microsatellite analysis, focusing on chromosomes 1p and 19q as well as 17p. With the clinical data of these patients, a combined loss of 1p and 19q would predict longer survival, but the loss of p53 could worsen the prognosis even with histological grade II. This diagnostic approach can be accepted and allows physicians to select an appropriate therapeutic modality including aggressive chemotherapy. Chromosome 22q loss has classically been a molecular marker of meningioma. We have conducted molecular genetic testing on a total of 63 tumors, including 15 atypical and 7 anaplastic meningiomas. A high incidence of deletion of at least part of 1p was observed in 67% of atypical and 86% of anaplastic meningiomas, showing molecular evidence for further treatment after simple removal. In addition, 12% of histologically benign meningiomas harbored 1p loss, indicating that patients with these tumors may need careful clinical follow-up with neuroimaging for recurrence. Detection of the allelic status of chromosome 1p may assist physicians in predicting the clinical prognosis.

Analysis of loss of chromosome 10q, DMBT1 homozygous deletions, and PTEN mutations in oligodendrogliomas.

Chromosomal deletions of 10q and candidate genes such as PTEN and DMBT1 have been thoroughly investigated in glioblastomas but few data specifically address oligodendrogliomas. In this study, 39 pure oligodendrogliomas were investigated for loss of heterozygosity (LOH) on 10q, PTEN mutations, and DMBT1 homozygous deletions. The LOH on 10q was found in 19 (48%) of 39 oligodendrogliomas and was closely related to anaplasia (p = 0.02), shorter time to progression (p = 0.0005), and poorer survival (p = 0.035). The DMBT1 homozygous deletions were found in 10 (26%) of 39 oligodendrogliomas but only one PTEN mutation was detected. The LOH on 10q is a strong predictor of survival and could be a valuable prognostic marker in oligodendrogliomas. Frequent inactivation of DMBT1 contrasting with rare mutations of PTEN may indicate that DMBT1 is preferentially involved in oligodendrogliomas. Nevertheless, the absence of a correlation with survival makes the role of DMBT1 in tumorigenesis still questionable and warrants further investigation.

Concurrent hypermethylation of multiple genes is associated with grade of oligodendroglial tumors.

Current evidence suggests that epigenetic changes play an important role in the evolution of human cancers. In this study, we evaluated whether hypermethylation of CpG islands at the gene promotor regions of several tumor-related genes is involved in the carcinogenesis of oligodendroglial tumors. We examined the methylation status of 11 genes in a series of 43 oligodendroglial tumors (19 oligodendrogliomas, 13 anaplastic oligodendrogliomas, 9 oligoastrocytomas, and 2 anaplastic oligoastrocytomas) by methylation-specific polymerase chain reaction. Our results showed that hypermethylation of CpG islands was detectable in 8 of 11 genes studied and 74% of tumors were hypermethylated in at least 1 gene. Promotor hypermethylations were detected in O6-methylguanine-DNA methyltransferase (MGMT), RB1, estrogen receptor, p73, p16INK4a, death-associated protein kinase, p15INK4b, and p14ARF at 60%, 34%, 30%, 16%, 12%, 10%, 7%, and 2%, respectively. No hypermethylation was detected in the promotors of glutathione-S-transferase P1, von Hippel-Lindau or the DNA mismatch repair (hMLH1) genes. Statistical analysis revealed that concordant hypermethylation of at least 2 genes, p16INK4a and p15INK4b were significantly associated with anaplastic oligodendroglial tumors, and hypermethylation of MGMT was significantly associated with loss of chromosome 19q and with combined loss of chromosomes 1p and 19q. More importantly, several candidate tumor suppressor genes such as p16INK4a, p15INK4b, and p73 that were previously reported as unmutated in oligodendroglial tumors were found to be hypermethylated in their CpG islands. Taken together, we conclude that hypermethylation of CpG islands is a common epigenetic event that is associated with the development of oligodendroglial tumors.

PTEN Is a Target of Chromosome 10q Loss in Anaplastic Oligodendrogliomas and PTEN Alterations Are Associated with Poor Prognosis

Allelic loss of 10q is a common genetic event in malignant gliomas, with three 10q tumor suppressor genes, ERCC6, PTEN, and DMBT1, putatively implicated in the most common type of malignant glioma, glioblastoma. Anaplastic oligodendroglioma, another type of malignant glioma, provides a unique opportunity to study the relevance of particular genetic alterations to chemosensitivity and survival. We therefore analyzed these three genes in 72 anaplastic oligodendrogliomas. Deletion mapping demonstrated 10q loss in 14 of 67 informative cases, with the PTEN and DMBT1 regions involved in all deletions but with the ERCC6 locus spared in two cases. Seven tumors had PTEN gene alterations; two had homozygous DMBT1 deletions, but at least one reflected unmasking of a germline DMBT1 deletion. No mutations were found in ERCC6 exon 2. Chemotherapeutic response occurred in two of the seven tumors with PTEN alterations, but with unexpected short survival times. PTEN gene alterations were not associated with poor therapeutic response in multivariate analysis, but were independently predictive of poor prognosis even after multivariate adjustment for both 10q and 1p loss. In anaplastic oligodendroglioma, therefore, PTEN is a target of 10q loss, and PTEN alterations are associated with poor prognosis, even in chemosensitive cases.

Pattern of Chromosome 16q Loss Differs between an Atypical Proliferative Lesion and an Intraductal or Invasive Ductal Carcinoma Occurring Subsequently in the Same Area of the Breast

Atypical proliferative lesions of the breast, such as atypical ductal hyperplasia and atypical papilloma, are considered to be precursors of breast carcinomas and have frequently been shown to have loss of heterozygosity (LOH) on chromosome 16q at the DNA level. We evaluated whether an atypical proliferative lesion and a carcinoma that subsequently occurred in the same area of the ipsilateral breast were of identical clonal origin in seven patients. Using DNA isolated from microdissected archival tissue of epithelial components of both the biopsy specimen of the atypical proliferative lesion and the mastectomy specimen of the carcinoma, the pattern of LOH on 16q was compared between these two lesions using polymerase chain reaction –microsatellite LOH analysis. As a control, LOH on 16q was examined in 13 cases of usual ductal hyperplasia, 10 usual papillomas, and 6 atypical ductal hyperplasias. In the seven cases, LOH on 16q was detected in three of the six atypical proliferative lesions and in five of the seven carcinomas, but the allele with LOH or a deleted region always differed between the two. LOH was detected in both atypical proliferative lesions and carcinomas in one case, only in the atypical proliferative lesion in two cases, and only in carcinomas in three cases. In the controls, LOH on 16q was absent in usual ductal hyperplasias or usual papillomas but was detected in two of six atypical ductal hyperplasias. Although atypical proliferative lesions were frequently confirmed to be of clonal nature with LOH on 16q, these lesions and carcinomas were considered to be clones, probably originated from a field with these clones.

Loss of chromosome 16q in lobular carcinoma in situ

Lobular carcinoma in situ (LCIS) and infiltrating lobular carcinoma may represent different forms of the same disease based on their frequent clinical association and similar histologic features. Patients with LCIS are at increased risk of multicentric and bilateral disease. Thus, LCIS may represent both a precursor to infiltrating lobular carcinoma and a marker of risk for breast cancer. To identify genomic alterations in LCIS, comparative genomic hybridization was performed on 17 cases without concurrent invasive carcinoma. Loss involving chromosome 16q was present in 88% of cases and was the sole detected alteration in 29%. Gain involving 1q was second in frequency, occurring in 41% of tumors, and in all cases was associated with loss of 16q. Other recurrent changes were loss involving 17p (18%), 8p (12%), and 12q24 (12%). E-cadherin immunohistochemistry was performed on all LCIS cases to evaluate the correlation of loss involving 16q22, the site of the E-cadherin gene, and altered protein expression. Most cases with 16q22 loss showed altered E-cadherin expression (12 of 13). These results in LCIS are similar to changes reported in infiltrating lobular cancer, confirming a genetic relationship between them. HUM PATHOL 32:292-296. Copyright © 2001 by W.B. Saunders Company

Absence of point mutations within the AML-1 gene in patients with MDS/AML and loss of chromosome 5q or 7.

There is increasing evidence that the acute myeloid leukemia 1 (AML-1) gene plays a versatile role in hematopoiesis, and its inactivation has been described in various hematopoetic disorders, e.g., leukemia or familial thrombocytopenia. AML-1 can be affected by various mechanisms, such as chromosomal translocations or point mutations. On the other hand, the specific underlying molecular lesions in myelodysplastic syndromes (MDS) or leukemias with aberrations of chromosomes 5q or 7, respectively, are largely unknown. Despite extraordinary scientific effort no specific genes on chromosome 5q or 7, which act as tumor suppressors, have definitely been identified. Therefore, it has recently been speculated that the AML-1 gene, even if distantly located on chromosome 21q22, may be involved in leukemogenesis in patients with aberrations at chromosome 5q or monosomy 7 [2]. Therefore, we sequenced all exons of the AML-1 gene in 15 patients with MDS/AML and deleted chromosome 5q or 7q, respectively. None of the patients analyzed had any AML-1 mutation.

Counting alleles reveals a connection between chromosome 18q loss and vascular invasion

The analysis of loss of heterozygosity (LOH) is perhaps the most widely used technique in cancer genetics. In primary tumors, however, the analysis of LOH is fraught with technical problems that have limited its reproducibility and interpretation. In particular, tumors are mixtures of neoplastic and nonneoplastic cells, and the DNA from the nonneoplastic cells can mask LOH. We here describe a new experimental approach, involving two components, to overcome these problems. First, a form of digital PCR was employed to directly count, one by one, the number of each of the two alleles in tumor samples. Second, Bayesian-type likelihood methods were used to measure the strength of the evidence for the allele distribution being different from normal. This approach imparts a rigorous statistical basis to LOH analyses, and should be able to provide more reliable information than heretofore possible in LOH studies of diverse tumor types.

Preferential Occurrence of Breast Carcinomas with Loss of Chromosome 16q and der(16)t(1;16)/der(1;16) in Middle-aged Patients with Hyperplasia of Mammary Glands

Structural and numerical alterations of chromosome 16 are considered to be commonly involved in the genesis of breast cancer. To reveal etiological factors that predispose cells to these alterations, we examined the frequencies of chromosome 16 aneusomy, 16q loss and 1;16 fusion indicating der(16)t(1;16)/der(1;16) by multi‐color fluorescence in situ hybridization in 46 tumors resected mostly from young (≤34 years old) or elderly (≥75 years old) women, and compared the results with those in a patient group representing a common age distribution of Japanese patients in whom chromosome 16 status in the tumor had already been studied. The correlation of these chromosome 16 alterations with age, hyperplasia in adjacent mammary glands, cancer history, and obesity indices was investigated in a total of 244 patients. In the present 46 tumors, the frequency of 16q loss and der(16)t(1;16) did not differ between 20 younger patients (30% and 15%) and 23 elderly patients (43% and 13%). However, the incidences of 16q loss and der(16)t(1;16) were low in comparison with the values of 64% and 38% in the 198 Japanese patients representing the common age distribution (P< 0.001). In addition, 16q loss and der(16)t(1;16) were more frequent in tumors arising in hyperplastic mammary glands (68%, 44%) than in those without (52%, 24%) (P< 0.01). Such correlations were not evident for 16cen aneusomy. Other etiological factors examined were not correlated with these chromosome 16 alterations. The 16q loss and der(16)t(1;16) formation were more frequently involved in the development of breast cancer in middle‐aged patients than in young and elderly patients. High‐level estrogens and/or sensitivity of mammary glandular cells to estrogens might induce breast cancers with structural changes of chromosome 16.

Analysis of the DMBT1 gene in carcinomas of the respiratory tract.

Loss of chromosome 10q is a critical step during the progression and metastasis formation of lung cancer. We recently defined 3 distinct regions of allelic imbalances and considered the DMBT1 gene at 10q25-q26 an interesting candidate for the most telomeric region. Therefore, we investigated DMBT1 in 25 cancer cell lines and 39 primary tumors of the respiratory tract. The analysis by RT-PCR and Northern blot hybridization revealed that the gene is expressed in all tumors and cell lines and diminished in the SCLC line H187, indicating that RT-PCR is critical when used as the single method for the evaluation of gene expression. No mutations were found by SSCP analysis of the cDNA and the partially known genomic sequence. Similarly, Southern blot hybridization was unable to detect homozygous deletions. Allelotyping of the markers D10S587, D10S1708 and D10S1723 located near or within the DMBT1 gene did not reach the peak incidence of the 3 minimally deleted regions that we recently defined. In summary, our data do not confirm previous findings reporting frequent loss of DMBT1 expression in lung cancer. However, they strengthen the notion that the responsible gene on chromosome 10q25-q26 mediating tumor progression and metastasis formation in respiratory tract cancer remains enigmatic.

Loss of Heterozygosity on Chromosome 10 Is More Extensive in Primary (De Novo) Than in Secondary Glioblastomas

Glioblastomas develop de novo (primary glioblastomas) or through progression from low-grade or anaplastic astrocytoma (secondary glioblastomas). There is increasing evidence that these glioblastoma subtypes develop through different genetic pathways. Primary glioblastomas are characterized by EGFR and MDM2 amplification/overexpression, PTEN mutations, and p16 deletions, whereas secondary glioblastomas frequently contain p53 mutations. Loss of heterozygosity (LOH) on chromosome 10 (LOH#10) is the most frequent genetic alteration in glioblastomas; the involvement of tumor suppressor genes, other than PTEN, has been suggested. We carried out deletion mappings on chromosome 10, using PCR-based microsatellite analysis. LOH#10 was detected at similar frequencies in primary (8/17; 47%) and secondary glioblastomas (7/13; 54%). The majority (88%) of primary glioblastomas with LOH#10 showed LOH at all informative markers, suggesting loss of the entire chromosome 10. In contrast, secondary glioblastomas with LOH#10 showed partial or complete loss of chromosome 10q but no loss of 10p. These results are in accordance with the view that LOH on 10q is a major factor in the evolution of glioblastoma multiform as the common phenotypic end point of both genetic pathways, whereas LOH on 10p is largely restricted to the primary (de novo) glioblastoma.

The human glia maturation factor-gamma gene: genomic structure and mutation analysis in gliomas with chromosome 19q loss

Human glia maturation factor-gamma (hGMF-gamma) is a recently identified gene that may be involved in glial differentiation, neural regeneration, and inhibition of tumor cell proliferation. The gene maps to the long arm of chromosome 19 at band q13.2, a region that is frequently deleted in human malignant gliomas and is thus suspected to harbor a glioma tumor suppressor gene. Given the putative role of hGMF-gamma in cell differentiation and proliferation and its localization to chromosome 19q13, this gene is an interesting candidate for the chromosome 19q glioma tumor suppressor gene. To evaluate this possibility, we determined the genomic structure of human hGMF-gamma and performed mutation screening in a series of 41 gliomas with and without allelic loss of chromosome 19q. Mutations were not detected, which suggests that hGMF-gamma is not the chromosome 19q glioma suppressor gene. However, the elucidation of the genomic structure of hGMF-gamma may prove useful in future investigations of hGMF-gamma in the normal adult and developing human nervous system.

Common regions of deletion on chromosome 22q12.3-q13.1 and 22q13.2 in human astrocytomas appear related to malignancy grade.

Approximately 30% of human astrocytomas have been reported to display allelic loss of the long arm of chromosome 22, suggesting the presence of a chromosome 22q astrocytoma suppressor gene. To define the most likely location for this putative tumor suppressor, we performed deletion mapping on 141 tumors using 16 chromosome 22q microsatellite markers. Allelic loss of 22q was observed in 2/12 (17%) of astrocytomas, 9/29 (31%) of anaplastic astrocytomas, and 38/100 (38%) of glioblastomas, consistent with a role for chromosome 22q loss in astrocytoma progression as well as formation. Twenty-two tumors exhibited allelic loss at every informative locus, consistent with loss of the entire arm of 22q. Twenty-seven tumors showed partial deletions, with one common region of deletion at 22q12.3-q13.1 between markers D22S280 and D22S282, and a second candidate region at 22q13.2 near the marker D22S1170. For the proximal candidate region, the incidence of allelic loss was similar between grades; for the distal locus, the incidence increased with grade, raising the possibility that the distal locus is involved in a later stage of astrocytoma tumorigenesis.

Correlation between Clinicopathological Features and Karyotype in Spindle Cell Sarcomas: A Report of 130 Cases from the CHAMP Study Group

Soft-tissue tumors have proved to be a fruitful area for the identification of reproducible cytogenetic aberrations, especially among pediatric round-cell sarcomas and lipomatous tumors. Thus far, however, data regarding sarcomas of monomorphic spindle cell type have been limited and somewhat disappointing, with the notable exception of synovial sarcoma. As part of an ongoing international collaborative study, 130 karyotyped spindle-cell sarcomas were reviewed and classified histologically, without knowledge of the clinical and karyotypic data, with the aim of identifying objective correlations between morphology, karyotype, and clinical parameters. Clonal chromosomal abnormalities were identified in 82 cases studied (63%), but only in the group of synovial sarcomas was there clear correlation between the cytogenetic findings, in the form of a consistent t(X;18)(p11;q11), and morphology. Among leiomyosarcomas (41 cases) and malignant peripheral nerve sheath tumors (MPNSTs; 27 cases) as well as in individual examples of rarer entities, there was a general tendency for karyotypic complexity associated with frequent loss or rearrangement of chromosome arms 1p, 10p, 11q, 12q, 17p, and 22q. Rearrangements of 17q (the region of the NF1 gene) were seen in 9/27 (33%) of MPNSTs. Among nine cases of solitary fibrous tumor (in which previous cytogenetic data are very limited) no consistent aberrations were identified. We conclude that, with the exception of synovial sarcoma, most spindle-cell sarcomas share with pleomorphic sarcomas the tendency for karyotypic complexity. There was no indication (in most of these lesions) that detectable cytogenetic aberrations could either facilitate their diagnosis or help to determine prognosis. There is a clear need to further study and understand the significance of multiple chromosomal abnormalities in this group of mesenchymal neoplasms with the particular goal of determining their role in the process of tumor development.

Genetic epidemiology of mutated K-rasproto-oncogene, altered suppressor genes, and microsatellite instability in colorectal adenomas

BACKGROUNDThe genetic epidemiology of colorectal adenomas has not been studied prospectively in colonoscopy patients without cancer.AIMSTo study genetic alterations in colorectal adenomas and correlate these with patient demographics and adenoma...

Involvement of mutations in the DPC4 promoter in endometrial carcinoma development.

To define the target of chromosome 18q loss of heterozygosity, which is prevalent in endometrial carcinomas, we made a deletion map from 64 tumors. Loss of heterozygosity on 18q was found in 20 tumors. Among these, 14 tumors carried deletions at the 18q21.1 region, where the DPC4 gene is located. DPC4 transcription was disturbed in all six of the tumors with deletions at 18q21.1 examined, which sharply contrasted with the positive transcription in 12 tumors that retained heterozygosity at the 18q21.1 region. However, in the 14 tumors with the 18q21.1 deletions, the remaining allele had the wild-type sequence of the DPC4 coding region instead of somatic mutations in the DPC4 coding region. We found a one- and two-base substitutions in the DPC4 promoter in two of the six tumors that showed disturbed DPC4 transcription. Chloramphenicol acetyltransferase assays clearly demonstrated that the mutant promoters had the potential to suppress or silence DPC4 transcription, implicating the DPC4 gene in endometrial carcinoma.