Loss of heterozygosity in epithelial cells obtained by bronchial brushing: clinical utility in lung cancer.
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To determine whether loss of heterozygosity (LOH) could be a useful diagnostic test for lung cancer, we evaluated LOH in cells obtained from bronchial brushings. Cells from radiographically normal and abnormal lungs were obtained from 55 patients undergoing diagnostic bronchoscopy. Among 38 patients with lung cancer, LOH was present in at least one chromosomal locus in 79%, whereas cytology was positive for malignant cells in 37%. LOH was not restricted to the airway containing the tumor; fifty-three percent of the cancer patients had LOH in the contralateral lung, as did 59% of patients without lung cancer. There was an association between the extent of LOH and proximity to the cancer. The LOH score, which combined measures of fractional allelic loss and percentage of cells with allelic loss, was greater in subjects with positive cytology and on the side of the tumor. A LOH score >10 was positive in 58% of tumor-bearing lungs, in 13% of the contralateral lungs in cancer patients, and in no patients without cancer. Our results suggest that extensive and widespread allelic loss, as indicated by a high LOH score, may be diagnostic of lung cancer. Additional studies will be needed to clarify the clinical potential of using bronchial epithelial cell LOH as a biomarker and diagnostic test for lung cancer. (+info)
Characterization of the regulatory domains of the human skn-1a/Epoc-1/Oct-11 POU transcription factor.
(66/1929)
The Skn-1a POU transcription factor is primarily expressed in keratinocytes of murine embryonic and adult epidermis. Although some POU factors expressed in a tissue-specific manner are important for normal differentiation, the biological function of Skn-1a remains unknown. Previous in vitro studies indicate that Skn-1a has the ability to transactivate markers of keratinocyte differentiation. In this study, we have characterized Skn-1a's transactivation domain(s) and engineered a dominant negative protein that lacked this transactivation domain. Deletional analysis of the human homologue of Skn-1a with three target promoters revealed the presence of two functional domains: a primary C-terminal transactivation domain and a combined N-terminal inhibitory domain and transactivation domain. Skn-1a lacking the C-terminal region completely lost transactivation ability, irrespective of the promoter tested, and was able to block transactivation by normal Skn-1a in competition assays. Compared with full-length, Skn-1a lacking the N-terminal region demonstrated either increased transactivation (bovine cytokeratin 6 promoter), comparable transactivation (human papillomavirus type 1a long control region), or loss of transactivation (human papillomavirus type 18 long control region). The identification of a primary C-terminal transactivation domain enabled us to generate a dominant negative Skn-1a factor, which will be useful in the quest for a better understanding of this keratinocyte-specific gene regulator. (+info)
Previous loss of chromosome 11 containing a suppressor locus increases radiosensitivity, neoplastic transformation frequency and delayed death in HeLa x fibroblast human hybrid cells.
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CGL1 (HeLa x fibroblast) hybrid cells have been utilized to study mechanisms of radiation-induced neoplastic transformation of human cells in vitro. Previous analysis has shown that loss of active tumor suppressor alleles on fibroblast chromosomes 11 and 14 may be required for radiation-induced neoplastic transformation of CGL1 cells. Loss of chromosome 11 alone was, therefore, found to be necessary but not sufficient for neoplastic transformation. We postulated that the loss of chromosome 11 may make the hybrid cells more susceptible to radiation-induced neoplastic transformation, since these cells have already undergone one of the required tumor suppressor loss events. Hybrid cells which have lost one copy of chromosome 11 were designated CON104(-11). CON104(-11) hybrid cells were found to have increased X-ray sensitivity and susceptibility to radiation-induced neoplastic transformation when compared with the parental CGL1 cells. In addition, the neoplastically transformed foci appear to arise earlier after radiation exposure in CON104(-11) versus CGL1 cells. Furthermore, the plating efficiency (PE) of the progeny of the irradiated CON104(-11) cells, growing in transformation flasks, is persistently lower than parental CGL1 cells during the 21 day assay period. The lower PE of the progeny of irradiated cells was attributed to the expression of delayed death/lethal mutations post-irradiation, a reflection of genomic instability. Taken together, the data indicate that previous loss of chromosome 11 may increase the radiation-induced genomic instability of the hybrid cells, leading to increased radiation sensitivity and neoplastic transformation potential. The data suggest that one possible function of the chromosome 11 tumor suppressor gene may be to help maintain genome stability after radiation damage. (+info)
The (4;11)(q21;p15) translocation fuses the NUP98 and RAP1GDS1 genes and is recurrent in T-cell acute lymphocytic leukemia.
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We determined the breakpoint genes of the translocation t(4;11)(q21;p15) that occurred in a case of adult T-cell acute lymphocytic leukemia (T-ALL). The chromosome 11 breakpoint was mapped to the region between D11S470 and D11S860. The nucleoporin 98 gene (NUP98), which is rearranged in several acute myeloid leukemia translocations, is located within this region. Analysis of somatic cell hybrids segregating the translocation chromosomes showed that the chromosome 11 breakpoint occurs within NUP98. The fusion partner of NUP98 was identified as the RAP1GDS1 gene using 3' RACE. RAP1GDS1 codes for smgGDS, a ubiquitously expressed guanine nucleotide exchange factor that stimulates the conversion of the inactive GDP-bound form of several ras family small GTPases to the active GTP-bound form. In the NUP98-RAP1GDS1 fusion transcript (abbreviated as NRG), the 5' end of the NUP98 gene is joined in frame to the coding region of the RAP1GDS1 gene. This joins the FG repeat-rich region of NUP98 to RAP1GDS1, which largely consists of tandem armadillo repeats. NRG fusion transcripts were detected in the leukemic cells of 2 other adult T-ALL patients. One of these patients had a variant translocation with a more 5' breakpoint in NUP98. This is the first report of an NUP98 translocation in lymphocytic leukemia and the first time that RAP1GDS1 has been implicated in any human malignancy. (+info)
RT-PCR evaluation of peripheral blood, bone marrow and peripheral blood stem cells in children and adolescents undergoing VACIME chemotherapy for Ewing's sarcoma and alveolar rhabdomyosarcoma.
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Peripheral blood stem cell support allows dose intensification of multiple cycle chemotherapy for metastatic tumors, including pediatric sarcomas. The VACIME protocol (vincristine, adriamycin, cyclophosphamide, ifosfamide, mesna and etoposide) utilizes peripheral blood stem cells (PBSC) collected following the treatment cycle as support for subsequent dose- and time-intensive chemotherapy. A critical assumption is that PBSC collected in this manner will be purged of residual tumor cells in vivo. We tested this assumption using sensitive reverse-transcriptase polymerase chain reaction (RT-PCR) to assess the presence of the characteristic translocations of the Ewing's sarcoma family of tumors (ESFT) and alveolar rhabdomyosarcoma (ARMS), t(11;22), and t(2;13), respectively. We used RT-PCR to evaluate 122 samples of peripheral blood (PB), bone marrow (BM) and PBSC collected from 12 pediatric patients with metastatic ESFT and ARMS. The samples included pre-therapy BM and PB, as well as BM, PB, and PBSC collections at various times in the VACIME treatment course. Molecular evidence of tumor contamination was detected in 1/40 PBSC collections from 12 patients. In all patients, we documented clearance of disease by RT-PCR in peripheral blood and bone marrow by week 9 of the VACIME protocol. In vivo purging in combination with the intensive VACIME regime appears to be effective in removing tumor cells from PBSC, bone marrow, and peripheral blood as detected by RT-PCR. (+info)
AF17q25, a putative septin family gene, fuses the MLL gene in acute myeloid leukemia with t(11;17)(q23;q25).
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The t(11;17) has been described in patients with acute myeloid leukemia (AML), and the AF17 gene was previously cloned as a fusion partner of the MLL gene in t(11;17)(q23;q21)-AML. We analyzed one patient with de novo AML and one with therapy-related AML with t(11;17)(q23;q25) and identified the AF17q25 gene on chromosome 17q25, a putative septin family gene, fused with MLL. AF17q25 encoded at least three kinds of proteins [type I (568 a.a.), type II (594 a.a.), and type III (574 a.a.)] that contained two kinds of different amino acid sequences at the COOH terminus. The MLL-AF17q25 fusion transcript consisted of type I AF17q25 transcript. The AF17q25 protein is homologous to septin family proteins, including H5, NEDD5, CDC10, and hCDCrel, which is one of the fusion partners of MLL in t(11;22)(q23;q11)-AML. These results suggest that AF17q25 and hCDCrel might define a new septin family particularly involved in the pathogenesis of 11q23-associated leukemia. (+info)
Assignment of the locus for hydrolethalus syndrome to a highly restricted region on 11q23-25.
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Hydrolethalus syndrome is a recessively inherited lethal malformation syndrome characterized by hydrocephaly with absent midline structures of the brain, micrognathia, polydactyly, and several other abnormalities, mostly in the midline structures. Hydrolethalus syndrome was described in 1981 in Finland, where the incidence is 1:20,000. Only a few cases have been reported elsewhere, and the pathogenesis has remained unknown. Here we report the assignment of the hydrolethalus syndrome locus to chromosome 11q23-25 in Finnish families. The initial genome scan was performed using DNA samples from only 15 affected individuals. In the next step, the hydrolethalus syndrome locus was assigned to an 8.5-cM interval between markers D11S4144 and D11S1351 by linkage analysis in eight families. Finally, the critical locus could be restricted by linkage disequilibrium and haplotype analyses to a 0.5-1-cM region between markers D11S933 and D11S934. Genealogical studies performed in 40 families affected by hydrolethalus revealed no regional clustering, suggesting a relatively early introduction of the disease mutation into the Finnish population and the spreading of the mutation with the inhabitation of the late-settlement area. (+info)
Allelic deletion at 11q23 is common in MYCN single copy neuroblastomas.
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Deletions of the long arm of chromosome 11 (11q) have been noted in primary neuroblastomas, but a comprehensive analysis has not been performed. Therefore, we analysed 331 neuroblastomas (295 sporadic, 15 familial and 21 tumor-derived cell lines) to determine the prevalence of 11q allelic deletions, to map the location of a putative tumor suppressor gene and to perform clinical correlative studies. Assays for loss of heterozygosity (LOH) were performed at 24 microsatellite loci spanning 11q. LOH was observed at multiple 11q loci in 129/295 (44%) sporadic neuroblastomas, 5/15 (33%) familial neuroblastomas, and 5/21 (24%) neuroblastoma cell lines. A single region of 2.1 cM within 11q23.3, flanked by markers D11S1340 and D11S1299, was deleted in all specimens with 11q LOH. Allelic loss at 11q23 was inversely related to MYCN amplification (P<0.001). Within the subset of cases with a single copy of MYCN, 11q LOH was associated with advanced stage disease (P=0.008), unfavorable histopathology (P=0.042), and decreased overall survival probability (P=0.008). However, 11q LOH was not independently prognostic in multivariate analyses. These data support the hypothesis that a tumor suppressor gene mapping within 11q23.3 is commonly inactivated during the malignant evolution of a large subset of neuroblastomas, especially those with unamplified MYCN. (+info)