Pediatric ALK+ anaplastic large cell lymphoma with t(3;8)(q26.2;q24) translocation and c-myc rearrangement terminating in a leukemic phase

Pediatric ALK-positive anaplastic large cell lymphoma (ALK+ ALCL) is usually associated with a favorable prognosis. ALK+ ALCL associated with a leukemic phase is uncommon, but has been associated with an aggressive clinical course and unfavorable prognosis. Overexpression of c-myc has been shown to be a consistent finding in ALK+, but not ALK-negative ALCL (ALK- ALCL), and the c-myc gene is considered a downstream target of deregulated ALK signaling. We describe a pediatric ALK+ ALCL with a leukemic phase at relapse. Similar to other rare cases described in the literature, it followed an aggressive clinical course despite multiple regimens of chemotherapy and bone marrow transplantation. Lymphoma cells showed aberrant ALK expression and c-myc overexpression. In addition to the characteristic t(2;5)(p23;q35) translocation, a t(3;8)(q26.2;q24) translocation was also present, and c-myc gene rearrangement was confirmed by FISH analysis. The findings in this case demonstrate the association of peripheral blood leukemic involvement and aggressive clinical course, and suggest that other factors, such as c-myc rearrangement, may be responsible for the aggressive clinical behavior in ALK+ ALCL.

The spectrum of myelodysplastic syndromes post-solid organ transplantation: A single institutional experience

An increased incidence of acute myeloid leukemia (AML) has recently been documented in patients post-solid organ transplantation but the incidence and types of myelodysplastic syndromes (MDS) occurring in this patient population are not known. We identified 5 patients (3M, 2F, age 48-64 years) who developed MDS ranging from 1.8 to 25 years (median 4.2 years) post-solid organ transplantation, only 2 patients had received azathioprine. The cumulative incidence of MDS in heart and lung transplant recipients at 15 years was 0.5% and 1.8%, respectively, which is markedly higher compared to the general population. Low-risk types of MDS predominated, 3 of 5 patients are alive (median 3.9 years) since diagnosis. Deletions of chromosome 20q, which have not been previously reported in post-transplant MDS/AML, were identified in 3 cases. Our findings expand the morphologic and cytogenetic spectrum of MDS occurring post-solid organ transplantation and suggest that mechanisms beside azathioprine toxicity might be important in disease pathogenesis.

CUTLL1, a novel human T-cell lymphoma cell line with t(7;9) rearrangement, aberrant NOTCH1 activation and high sensitivity to gamma-secretase inhibitors

Activating mutations in NOTCH1 are present in over 50% of human T-cell lymphoblastic leukemia (T-ALL) samples and inhibition of NOTCH1 signaling with gamma-secretase inhibitors (GSI) has emerged as a potential therapeutic strategy for the treatment of this disease. Here, we report a new human T-cell lymphoma line CUTLL1, which expresses high levels of activated NOTCH1 and is extremely sensitive to gamma-secretase inhibitors treatment. CUTLL1 cells harbor a t(7;9)(q34;q34) translocation which induces the expression of a TCRB-NOTCH1 fusion transcript encoding a membrane-bound truncated form of the NOTCH1 receptor. GSI treatment of CUTLL1 cells blocked NOTCH1 processing and caused rapid clearance of activated intracellular NOTCH1. Loss of NOTCH1 activity induced a gene expression signature characterized by the downregulation of NOTCH1 target genes such as HES1 and NOTCH3. In contrast with most human T-ALL cell lines with activating mutations in NOTCH1, CUTLL1 cells showed a robust cellular phenotype upon GSI treatment characterized by G1 cell cycle arrest and increased apoptosis. These results show that the CUTLL1 cell line has a strong dependence on NOTCH1 signaling for proliferation and survival and supports that T-ALL patients whose tumors harbor t(7;9) should be included in clinical trials testing the therapeutic efficacy NOTCH1 inhibition with GSIs.

Variant translocation with a deletion of derivative (9q) in a case of Philadelphia chromosome positive (Ph +) essential thrombocythemia (ET), a variant of chronic myelogenous leukemia (CML) with a poor prognosis

Patients presenting with thrombocytosis require thorough clinical and laboratory evaluation to determine whether they suffer from essential thrombocythemia or another myeloproliferative disorder. This distinction becomes increasingly relevant as targeted agents become available to treat specific myeloproliferative diseases. Cytogenetic testing plays a major role in this analysis. This study presents a patient with Philadelphia chromosome positive (Ph + ) thrombocytosis and a cryptic der(9q)t(5;9)t(9;22) not found by conventional cytogenetics, whose disease progressed within 2 years to typical myeloblastic crisis of CML. It discusses the entity of Ph + ET, the utility of molecular cytogenetic testing in the diagnosis of this unusual disease entity and the importance of cytogenetic testing in the prognosis of ET.

Nucleotide sequence, transcription map, and mutation analysis of the 13q14 chromosomal region deleted in B-cell chronic lymphocytic leukemia

Deletions of the 13q14 chromosome region are associated with B-cell chronic lymphocytic leukemia (B-CLL) and several other types of cancer, suggesting the presence of a tumor suppressor gene. In previous studies the minimal region of deletion (MDR) was mapped to a less than 300-kilobase (kb) interval bordered by the markers 173a12-82 and 138G4/1.3R. For the identification of the putative tumor suppressor gene, the entire MDR (approximately 347 kb) has been sequenced, and transcribed regions have been identified by exon trapping, EST-based full-length complementary DNA cloning, database homology searches, and computer-assisted gene prediction analyses. The MDR contains 2 pseudogenes and 3 transcribed genes: CAR, encoding a putative RING-finger containing protein; 1B4/Leu2, generating noncoding transcripts; and EST70/Leu1, probably representing another noncoding gene (longest open reading frame of 78 codons). These genes have been sequenced in 20 B-CLL cases with 13q14 hemizygous deletion, and no mutations were found. Moreover, no somatic variants were found in the entire MDR analyzed for nucleotide substitutions by a combination of direct sequencing and fluorescence-assisted mismatch analysis in 5 B-CLL cases displaying 13q14-monoallelic deletion. The nondeleted allele of the CAR and EST70/Leu1 genes was expressed in B-CLL specimens, including those with monoallelic loss, whereas no expression of 1B4/Leu2 was detectable in B-CLL, regardless of the 13q14 status. These results indicate that allelic loss and mutation of a gene within the MDR is an unlikely pathogenetic mechanism for B-CLL. However, haplo-insufficiency of one of the identified genes may contribute to tumorigenesis. (Blood. 2001;97:2098-2104)

Mapping the sites of putative tumor suppressor genes at 6p25 and 6p21.3 in cervical carcinoma: occurrence of allelic deletions in precancerous lesions

Allelic deletions on the short arm of chromosome 6 (6p) are one of the common, possibly early, genetic changes that occur in the pathogenesis of cervical carcinoma (CC). Previous loss of heterozygosity (LOH) studies in CC identified a number of critical regions of deletions on 6p. However, the precise location of minimally deleted regions and their role in precancerous lesions have not been well characterized. To address these questions, we first performed a detailed LOH analysis on 6p in 59 cases of invasive CC. The pattern of LOH identified two minimal regions of deletions, one spanning a 5 cM genetic distance at 6p25 and a second site of 10.3 cM deletion mapping to 6p21.3. The 6p21.3 minimal deletion spans HLA class I genes. To understand the role of 6p genetic alterations in the development of CC, we also investigated 12 high-grade and 4 low-grade cases of cervical intraepithelial neoplasia (CIN) for LOH after laser microdissection. The high-grade CINs exhibited 91.7% LOH, and low-grade CINs had 50% LOH. These findings implicate the presence of at least two tumor suppressor genes on 6p relevant to CC and suggest that these genetic alterations occur very early in CC development. This study should therefore facilitate the identification of tumor suppressor genes on 6p and may identify which CINs are at high risk of progressing to invasive CC.

A high-resolution map of human chromosome 12

Our sequence-tagged site-content map of chromosome 12 is now integrated with the whole-genome fingerprinting effort. It provides accurate and nearly complete bacterial clone coverage of chromosome 12. We propose that this integrated mapping protocol serves as a model for constructing physical maps for entire genomes.

MAD2 haplo-insufficiency causes premature anaphase and chromosome instability in mammalian cells

The mitotic checkpoint protein hsMad2 is required to arrest cells in mitosis when chromosomes are unattached to the mitotic spindle. The presence of a single, lagging chromosome is sufficient to activate the checkpoint, producing a delay at the metaphase-anaphase transition until the last spindle attachment is made. Complete loss of the mitotic checkpoint results in embryonic lethality owing to chromosome mis-segregation in various organisms. Whether partial loss of checkpoint control leads to more subtle rates of chromosome instability compatible with cell viability remains unknown. Here we report that deletion of one MAD2 allele results in a defective mitotic checkpoint in both human cancer cells and murine primary embryonic fibroblasts. Checkpoint-defective cells show premature sister-chromatid separation in the presence of spindle inhibitors and an elevated rate of chromosome mis-segregation events in the absence of these agents. Furthermore, Mad2+/- mice develop lung tumours at high rates after long latencies, implicating defects in the mitotic checkpoint in tumorigenesis.

Trisomy 1q, 2, and 20 in a case of hepatoblastoma: possible significance of 2q35-q37 and 1q12-q21 rearrangements

Combined cytogenetic, chromosome painting, and spectral karyotyping (SKY) analyses in a case of hepatoblastoma revealed a karyotype of 49,XY,+Y,+der(2)t(2;3)(q35;q25),der(3)t(1;3)(q12; q25),+20. Trisomy 1q, 2, and 20 identified in the present case are consistent with the previously reported cytogenetic alterations in hepatoblastoma. The breakpoints at 1q12 and 2q35 identified in this case have also been reported previously as nonrandom changes. The frequent occurrence of these rearrangements in hepatoblastoma suggests that they may be of pathogenic significance.

Identification of a 6-cM minimal deletion at 11q23.1-23.2 and exclusion of PPP2R1B gene as a deletion target in cervical cancer

Previous functional and deletion mapping studies on cervical cancer (CC) have implicated one or more tumor suppressor genes (TSGs) on chromosome 11 at q13 and q22-24 regions. Of these, the 11q22-24 region exhibits frequent allelic deletions in a variety of solid tumor types, suggesting the presence of critical genes for tumor suppression in this region. However, the precise region of deletion on 11q is not clearly defined in CC. In an attempt to accurately map the deleted region, we performed an extensive loss of heterozygosity (LOH) mapping in 58 tumors using 25 polymorphic loci on both the short and long arms. The pattern of LOH identified three sites of deletions, two on 11p (p15.11-p15.3 and p12-13), and one on 11q (q23.1-q23.2). The 11q23.1-q23.2 exhibited highest frequency (60.6%) of deletions, suggesting that this could be the site of a candidate TSG in CC. The minimal deletion at 11q23.1-23.2 was restricted to a 6-cM region between 123.5 and 129.5 cM genetic distance on chromosome 11, identifying the site of a potential TSG important in the pathogenesis of CC. At least five known genes and 28 UniGene clusters were mapped to the present commonly deleted region. In addition, we have excluded a previously known TSG PPP2R1B at 11q23 as a deletion target in CC. The definition of the minimal deletion and the availability of expressed sequence resources should facilitate the identification of the candidate TSG.

Human Fas associated factor 1, hFAF1, gene maps to chromosome band 1p32

Human Fas associated factor 1 protein (hFAF1) is involved in the positive regulation of Fas signaling even though it can not initiate the signal for itself. By chromosomal assignment using somatic cell hybrids (CASH), the hFAF1 gene was located on human chromosome 1 between markers D1S443 and D1S197. The hFAF1 gene was mapped to human chromosome band 1p32 by FISH utilizing a genomic PAC clone containing the gene. In genomic Southern analysis using hFAF1 cDNA as a probe, several bands appeared in three different restriction enzyme digestions. The single band appearance in FISH analysis compared to several bands in Southern blots implies that the hFAF1 gene would be rather big or that an additional hFAF1 gene isotype(s) might be present in close vicinity.

Genetic analysis of the APAF1 gene in male germ cell tumors

Cytogenetic and molecular analyses have shown that the chromosome band 12q22 is recurrently deleted in male germ cell tumors (GCTs), indicating the presence of a candidate tumor suppressor gene (TSG) in this region. To identify the TSG, we mapped the APAF1 gene, a proapoptotic mammalian homologue of ced-4, to chromosomal band 12q22, that suggested that this might be the candidate deleted gene in GCTs. We further localized the gene between the polymorphic markers D12S1671 and D12S1082 at 12q22 to determine the role of APAF1 in the pathogenesis of GCT, and we characterized its normal genomic structure and analyzed its alterations in GCTs. The APAF1 gene comprises 27 exons, with the coding region spanning 26. The region containing APAF1 was found to be deleted in GCT by fluorescence in situ hybridization analysis, but without evidence of coding sequence alterations. RT-PCR and Western blot analysis showed APAF1 gene expression at detectable levels in all GCT cell lines analyzed. An aberrant-sized APAF1 protein was seen in one cell line. This and 2 other cell lines carrying APAF1 deletions also exhibited defects in dATP-mediated caspase-3 activation. Caspase-3 activity was effectively restored by addition of recombinant caspase-9 and APAF1 proteins, and to a lesser extent by caspase-9 alone, but not by APAF1 alone. These data do not support a TSG role for APAF1, but defects in other components of the apoptotic pathway that may be related to 12q22 deletion cannot be ruled out. Genes Chromosomes Cancer 28:258-268, 2000.

Mutagen sensitivity and environmental exposures as contributing causes of chromosome 3p losses in head and neck cancers

The interaction between environmental exposures and host susceptibility may lead to specific mutational events within head and neck squamous cell carcinoma (HNSCC). Furthermore, this interplay may determine not only the probability of cancer development but also the biologic characteristics of the tumor once it occurs. To better understand the relationship of mutagen sensitivity and tobacco and/or alcohol consumption on HNSCC carcinogenesis, we examined loss of heterozygosity on chromosome 3p in 58 HNSCCs using 10 microsatellite markers. Mutagen sensitivity was determined in vitro by quantitating bleomycin-induced chromatid breaks utilizing peripheral blood lympocytes from respective patients. Forty-six of the 58 invasive cancers showed allelic loss at one or more loci. Consistent with previous investigations, three discrete regions of deletions were identified: 3p13-14.2, 3p21.1-21. 2, and 3p25.1-26.1. The frequency and types of deletions were dependent upon tobacco and alcohol exposures. The distal region of 3p but not the remaining two regions was most frequently influenced by tobacco exposure. In contrast, heavy alcohol use when combined with tobacco use was associated with whole-arm loss of 3p rather than identifiable site-specific damage. Furthermore, this combined influence of alcohol and tobacco exposures on whole-arm loss was most apparent in those patients who expressed mutagen-sensitivity; the odds ratio of whole-arm loss increasing from 2.67 (95% CI 0. 21-33.49) in those individuals who were mutagen resistant to 13.5 (95% CI 1.3-136.0; P = 0.02 by Fisher's exact test) in those who were mutagen sensitive. An assessment of clinical parameters in this population demonstrated that patients with whole-arm loss were more likely to present with cervical lymph node metastases and advanced stage disease than patients with partial losses. Results indicate that various environmental exposures as well as the expression of mutagen sensitivity will influence the types of chromosome 3p allelic losses in head and neck cancers as well as the behavior of disease once it develops.

A 3-Mb high-resolution BAC/PAC contig of 12q22 encompassing the 830-kb consensus minimal deletion in male germ cell tumors

Cytogenetic and molecular genetic analyses have shown that the 12q22 region is recurrently deleted in male germ cell tumors (GCTs), suggesting that this site may harbor a tumor suppressor gene (TSG). Previous loss of heterozygosity (LOH) analyses identified a consensus minimal deleted region between the markers D12S377 and D12S296, and a YAC clone contig covering the region was generated. Here, we describe a high-resolution sequence-ready physical map of this contig covering a 3-Mb region. The map comprised of 52 cosmids, 49 PACs, and 168 BACs that were anchored to the previous YAC contig; 99 polymorphic, nonpolymorphic, EST, and gene-based markers are now placed on this map in a unique order. Of these, 61 markers were isolated in the present study, including one that was polymorphic. In addition, we have narrowed the minimal deletion to approximately 830 kb between D12S1716 (proximal) and P382A8-AG (distal) by LOH analysis of 108 normal-tumor DNAs from GCT patients using 21 polymorphic STSs. These physical and deletion maps should prove useful for identification of the candidate TSG in GCTs, provide framework to generate complete DNA sequence, and ultimately generate a gene map of this segment of the chromosome 12. [The sequence data described in this paper have been submitted to the Genome Survey Sequence under accession nos. AQ254896-AQ254955 and AQ269251-AQ269266. Online supplementary material is available at http://www.genome.org]

Cloning and genomic organization of beclin 1, a candidate tumor suppressor gene on chromosome 17q21

The beclin 1 (BECN1) gene encodes a 60-kDa coiled-coil protein that interacts with the prototypic apoptosis inhibitor Bcl-2. Previous studies indicate that beclin 1 maps to a region approximately 150 kb centromeric to BRCA1 on chromosome 17q21 that is commonly deleted in breast, ovarian, and prostate cancer. The complete cDNA sequence of beclin 1 encodes a 2098-bp transcript, with a 120-bp 5' UTR, 1353-bp coding region, and 625-bp 3' UTR. Hybridization screening of a human genomic PAC library identified PAC 452O8, which contains the complete beclin 1 gene. Determination of the exon-intron structure of beclin 1 reveals 12 exons, ranging from 61 to 794 bp, which extend over 12 kb of the human genome. FISH analysis of human breast carcinoma cell lines using PAC 452O8 as probe identified allelic beclin 1 deletions in 9 of 22 cell lines. Sequencing of genomic DNA from 10 of these cell lines revealed no mutations in coding regions or splice junctions. Additionally, Northern blot analysis of 11 cell lines did not identify any abnormalities in beclin 1 transcripts. These results indicate that human breast carcinoma cell lines frequently contain allelic deletions of beclin 1, but not beclin 1 coding mutations.

A 3-Mb high-resolution BAC/PAC contig of 12q22 encompassing the 830-kb consensus minimal deletion in male germ cell tumors

Cytogenetic and molecular genetic analyses have shown that the 12q22 region is recurrently deleted in male germ cell tumors (GCTs), suggesting that this site may harbor a tumor suppressor gene (TSG). Previous loss of heterozygosity (LOH) analyses identified a consensus minimal deleted region between the markers D12S377 and D12S296, and a YAC clone contig covering the region was generated. Here, we describe a high-resolution sequence-ready physical map of this contig covering a 3-Mb region. The map comprised of 52 cosmids, 49 PACs, and 168 BACs that were anchored to the previous YAC contig; 99 polymorphic, nonpolymorphic, EST, and gene-based markers are now placed on this map in a unique order. Of these, 61 markers were isolated in the present study, including one that was polymorphic. In addition, we have narrowed the minimal deletion to approximately 830 kb between D12S1716 (proximal) and P382A8-AG (distal) by LOH analysis of 108 normal-tumor DNAs from GCT patients using 21 polymorphic STSs. These physical and deletion maps should prove useful for identification of the candidate TSG in GCTs, provide framework to generate complete DNA sequence, and ultimately generate a gene map of this segment of the chromosome 12. [The sequence data described in this paper have been submitted to the Genome Survey Sequence under accession nos. AQ254896-AQ254955 and AQ269251-AQ269266. Online supplementary material is available at http://www.genome.org]

Translocation (4;15)(p16;q24): a novel reciprocal translocation in a patient with BCR/ABL negative myeloproliferative syndrome progressing to blastic phase

A patient with BCR/ABL negative myeloproliferative syndrome with a 46,XY,del(3)(q21), t(4;15)(p16;q24) karyotype is described. Fluorescence in situ hybridization performed with chromosomes 4 and 15 painting probes confirmed a novel reciprocal (4;15) translocation. The absence of crkl tyrosine phosphorylation, no activation of the abl kinase as measured by autophosphorylation, and a normal-size abl transcript suggest an alternative mechanism for leukemogenesis to that operative in Ph positive BCR/ABL positive chronic myeloid leukemia. A number of genes potentially relevant to tumorigenesis, some involving the ras signaling pathway, map to the 4p16 and 15q24 chromosome regions.

Chromosomal amplification is associated with cisplatin resistance of human male germ cell tumors

Chemotherapy resistance of tumors is an important biological and clinical problem. Studies from many tumor types have indicated that resistance may be based on multiple genetic pathways. Human male germa cell tumors (GCTs) are an especially good model system to study the genetic basis of tumor sensitivity and resistance to chemotherapy. GCTs are exquisitely sensitive to treatment with DNA-damaging drugs such as cisplatin, rarely exhibit TP53 gene mutations, express normal p53 protein, and undergo p53-mediated apoptosis upon drug treatment. A small proportion of tumors (20-30% of metastatic lesions) escape the apoptotic response and result in treatment resistance. We have recently shown (J. Houldsworth, et al., Oncogene, 16: 2345-2359, 1998) that in a subset of such tumors, resistance is linked to TP53 gene mutations. In a further search for genetic mechanisms underlying resistance, we subjected a panel of 17 tumors from relapse-free patients (sensitive) and 17 chemotherapy-resistant tumors to comparative genomic hybridization analysis to identify possible amplified regions (implying amplified/overexpressed genes) associated with resistance. With the exception of 12p11.2-12, high level amplification was not detected in any of the sensitive tumors. We have identified eight amplified regions (1q31-32, 2p23-24, 7q21, 7q31, 9q22, 9q32-34, 15q23-24, and 20q11.2-12) in five resistant tumors, which suggests that chromosomal and, hence, gene amplification may comprise a pathway to drug resistance. Identification of amplified/overexpressed genes at these sites may elucidate new genetic pathways of chemotherapy resistance in GCTs and possibly also in other tumors.

Nonsyntenic amplification of MYC with CDK4 and MDM2 in a malignant mixed tumor of salivary gland

Karyotypic analysis of a metastatic malignant mixed tumor of the salivary gland revealed the presence of double minute chromosomes (dmin), indicative of gene amplification. Comparative genomic hybridization analysis of DNA extracted from the primary and a renal metastasis indicated overt amplification of DNA sequences derived from 8q23-24 and 12q13-15 regions. Subsequent Southern blot analysis of tumor DNA from the metastasis with the use of probes previously mapped to those regions indicated amplification of MYC at 8q23-24 and CDK4 and MDM2 at 12q13-15. Fluorescence in situ hybridization of differentially labeled MYC and MDM2 genes hybridized to tumor metaphase chromosomes revealed an independent nonsyntenic amplification of MYC and MDM2 on dmin in this tumor.

Type I transforming growth factor beta receptor maps to 9q22 and exhibits a polymorphism and a rare variant within a polyalanine tract

In a search for mutations of the type I transforming growth factor beta receptor (TbetaR-I), we mapped the gene to 9q22 and found a common polymorphism [TbetaR-I(6A)] and a rare variant [TbetaR-I(10A)] of TbetaR-I, causing an in-frame deletion of three alanines and an in-frame insertion of one alanine, respectively, in the receptor's extracellular domain. The biological relevance of the polymorphism TbetaR-I(6A) was investigated. When TbetaR-I(6A) was transiently transfected into TbetaR-I-deficient cells, the growth-inhibitory effects of transforming growth factor beta were restored. TbetaR-I(6A) and TbetaR-I(10A) frequency were assessed in 108 tumor samples and 80 nontumor samples from patients with a diagnosis of cancer, as well as in 118 normal blood donors of comparable ethnic composition. The frequency of TbetaR-I(6A) heterozygotes was fairly similar in normal blood donors (8%), in nontumor DNA of patients with a diagnosis of cancer (10%), and in tumor samples (14%). However, the frequency of TbetaR-I(6A) homozygotes among nontumor (4%) and tumor (8%) samples obtained from patients with a diagnosis of cancer was higher than that predicted by the Hardy-Weinberg law. The clinical and biological significance of TbetaR-I(6A) homozygosity needs to be further investigated.

Human male germ cell tumor resistance to cisplatin is linked to TP53 gene mutation

Male germ cell tumors (GCTs) are uniquely sensitive to cisplatin-based chemotherapy, with more than 90% of newly diagnosed cases cured. The underlying cause for resistance to treatment in 20-30% of metastatic lesions remains to be identified. Unlike other solid tumors, no mutations in the TP53 gene have been identified to date in random panels of GCT specimens, which could account for the exquisite sensitivity of these tumors to genotoxic insult. However, in a panel of resistant GCTs that did either not respond to cisplatin-based chemotherapy or subsequently relapsed and resulted in the death of the patient, we have now identified a subset of tumors to contain TP53 mutations within exons 6-9. A cell line derived from one of these tumors (228A) displayed the same TP53 mutation as the tumor specimen, expressed only mutant TP53 mRNA, and exhibited a relative resistance to cisplatin in vitro in comparison to a cell line (218A) derived from a responsive tumor with wild-type TP53. The resistant cell line displayed a much reduced apoptotic cell death and did not exhibit an induction of transcription of the p53-responsive genes WAF1 and MDM2 following cisplatin treatment, compared to that observed in the sensitive cell line. The levels of bax, an agonist of apoptosis, were found to be reduced in the resistant cell line. The simplest explanation for the resistance of this subset of GCTs that are resistant to cisplatin-based chemotherapy, is the inability of the cells to mount an apoptotic response following exposure due to a functionally inactivating mutation in the TP53 gene.

A genetic perspective of male germ cell tumors

Adult human male germ cell tumors (GCTs) arise by transformation of germ cells (GCs). The transformed GCs exhibit pluripotentiality to differentiate into embryonic, extra-embryonic, and somatic tissue types, and are highly sensitive to cisplatin-based chemotherapy. Recent investigations into the genetics of GCTs have advanced methods of diagnosis and provided leads to the understanding of molecular basis of transformation, differentiation, and sensitivity/resistance. Cytogenetic and molecular cytogenetic studies have identified multiplication of 12p, manifested in i(12p) or tandem duplication of 12p, as a unique change in GCTs which serves as a diagnostic marker. Ectopic over-expression of cyclin D2, a gene mapped to 12p, as early as in carcinoma in situ identifies a candidate gene in GC transformation. Genetic alterations identified in the tumor suppressor genes deleted in colorectal cancer, retinoblastoma 1 and non-metastatic protein 23 (NME) in GCT suggest that their inactivation play a key role in transformation or differentiation. A number of regions of chromosomal deletion have been identified including those previously known to be deleted in various tumor types and novel candidate tumor suppressor gene sites such as 12q13, 12q22, and 5p15.1-15.2. Identification and characterization of the genes in these sites will provide important clues in understanding the biology of GCT. The molecular studies have also enumerated several possible differentiation controls such as switching of KIT and mast cell growth factor gene expression in a lineage-associated manner, and loss of certain types of genes such as NME in teratomas that may act in a dominant negative fashion in differentiation. The exquisite sensitivity of these tumors to chemotherapy is reflected in their over-expression of wild-type p53 protein and lack of TP53 mutations. These data indicate that multiple genetic events play a role in distinct pathways in the development of GCT, and further elucidation of the underlying genetic and biochemical mechanisms is central to unraveling biology and improving treatment of GCT.

Teratoma with malignant transformation: diverse malignant histologies arising in men with germ cell tumors

PURPOSE

Teratoma with malignant transformation refers to a form of germ cell tumor in which a somatic teratomatous component becomes morphologically malignant and develops aggressive growth. We evaluated the spectrum of histologies, chromosomal abnormalities and clinical outcome in patients with teratoma with malignant transformation.

MATERIALS AND METHODS

We identified 46 patients with germ cell tumor meeting morphologic criteria for malignant transformation. Histology, disease extent and treatment were correlated with survival. Tumors in 12 patients were studied by conventional cytogenetics or molecular genetic techniques for the isochromosome 12p [i(12p)], a marker for germ cell tumor, as well as other chromosomal abnormalities.

RESULTS

The site of first detection of malignant transformation occurred in the primary tumor of 21 cases (44%), at a metastatic site in 20 (43%) and in both sites in 5 (10%). Sarcoma was the most frequent histology, identified in 29 patients (63%) with rhabdomyosarcoma the most common subtype. Seventeen tumors (37%) contained a solid tumor histology other than sarcoma, with adenocarcinoma and primitive neuroectodermal tumor as the most common histologies. Four patients with mediastinal germ cell tumor containing sarcoma also had hematological malignancies, including a focus of nonHodgkin's lymphoma in the mediastinal primary tumor (1) and nonlymphocytic leukemia in spleen or bone marrow (3). Patients who had teratoma with malignant transformation components confined to the testis or retroperitoneum completely resected experienced a longer survival than those with distant metastases or incompletely resected tumors (p = 0.003). Chromosomal abnormalities associated with germ cell tumor (i[12p]) were identified in 11 of 12 tumors containing adenocarcinoma, primitive neuroectodermal tumor, sarcoma and leukemia. In addition to i (12p), chromosomal rearrangements characteristic of the transformed histology were detected in 4 tumors.

CONCLUSIONS

A variety of nongerm cell histologies, including sarcoma, adenocarcinoma, primitive neuroectodermal tumor and leukemia, may occur in association with germ cell tumor. Chromosomal abnormalities in these tumors include i (12p), reflecting germ cell tumor clonality, as well as chromosomal abnormalities associated with the transformed histology. These tumors do not respond like germ cell tumor to cisplatin-containing chemotherapy regimens. Treatment should be tailored according to that used in standard management of the transformed histology, and surgical resection is the mainstay of therapy.

Physical mapping of a commonly deleted region, the site of a candidate tumor suppressor gene, at 12q22 in human male germ cell tumors

A candidate tumor suppressor gene (TSG) site at 12q22 characterized by a high frequency of loss of heterozygosity (LOH) and a homozygous deletion has previously been reported in human male germ cell tumors (GCTs). In a detailed deletion mapping analysis of 67 normal-tumor DNAs utilizing 20 polymorphic markers mapped to 12q22-q24, we identified the limits of the minimal region of deletion at 12q22 between D12S377 (proximal) and D12S296 (distal). We have constructed a YAC contig map of a 3-cM region of this band between the proximal marker D12S101 and the distal marker D12S346, which contained the minimal region of deletion in GCTs. The map is composed of 53 overlapping YACs and 3 cosmids onto which 25 polymorphic and nonpolymorphic sequence-tagged sites (STSs) were placed in a unique order. The size of the minimal region of deletion was approximately 2 Mb from overlapping, nonchimeric YACs that spanned the region. We also developed a radiation hybrid (RH) map of the region between D12S101 and D12S346 containing 17 loci. The consensus order developed by RH mapping is in good agreement with the YAC STS-content map order. The RH map estimated the distance between D12S101 and D12S346 to be 246 cR8000 and the minimal region of deletion to be 141 cR8000. In addition, four genes that were previously mapped to 12q22 have been excluded as candidate genes. The leads gained from the deletion mapping and physical maps should expedite the isolation and characterization of the TSG at 12q22.

Deletion mapping identifies loss of heterozygosity at 5p15.1-15.2, 5q11 and 5q34-35 in human male germ cell tumors

Cytogenetic and loss of heterozygosity (LOH) studies of chromosome 5 in male germ cell tumors (GCTs) previously reported suggested the presence of one or more tumor suppressor genes (TSGs) on this chromosome which may play a role in the development of these tumors. In an attempt to further characterize allelic deletions on chromosome 5, we performed a detailed deletion mapping utilizing 66 normal-tumor DNAs from male GCTs assaying 24 polymorphic markers mapped to both the short and long arms. Thirty-seven (56%) tumors exhibited LOH at one or more loci. Loss of one allele at all informative loci was found in 15 of 37 (40.5%) cases suggesting monosomy of chromosome 5. The pattern of LOH in the remaining 22 (59.5%) tumors revealed regional losses identifying three common sites of deletions at 5p15.1-15.2, 5q11, and 5q34-35, respectively. The distribution of allelic deletions was found to be similar in all histologic subtypes with predominance of monosomy in teratomas. Thus, the present study revealed 2 types of chromosome 5 abnormalities in male GCTs, genetic monosomy and regional deletion, the latter identifying three novel sites of candidate TSGs. These data suggest that loss of genetic information on chromosome 5 plays an important role in male GCT development.

Chromosomal assignment of human ID1 and ID2 genes

The Id (inhibitor of DNA binding) proteins regulate transcription during development by interacting with transcription factors. Three human genes, ID1, ID2, and ID3, have been identified that belong to this family of transcription regulators. We show, by somatic cell hybridization and fluorescence in situ hybridization experiments, that ID1 and ID2 are localized at 20q11 and 2p25, respectively.

p53 overexpression as a marker of poor prognosis in mantle cell lymphomas with t(11;14)(q13;q32)

The t(11;14)(q13;q32) translocation, which juxtaposes the BCL1 oncogene with the Ig heavy chain locus, has been associated with an uncommon subtype of non-Hodgkin's lymphoma (NHL) termed mantle cell lymphoma (MCL). To date, no molecular marker that serves as an indicator of tumor progression or clinical prognosis has been described for NHLs with this translocation. We examined a panel of NHLs with t(11;14) for overexpression of p53 and correlated the results with single-strand conformation polymorphism (SSCP) analysis, karyotypic features, and clinical course. NHLs with t(11;14) were identified from 30 patients. The diagnosis was MCL for 23 of 30, small lymphocytic lymphoma for 4 of 30, and diffuse large-cell lymphoma for 3 of 30 cases. The results of immunohistochemistry analysis using a monoclonal anti-p53 antibody on paraffin-embedded specimens were compared with the SSCP data, the tumor karyotypes, and clinical course of each patient. DNA sequencing of exons was performed on cases that showed conformational changes by SSCP analysis. NHLs from 5 of 23 patients with MCL were positive for p53 overexpression. Deletions of chromosome 17p were identified in 2 of 30 cases, both of which were MCLs showing p53 overexpression. Two of the five MCLs with p53 overexpression showed evidence for TP53 mutations. None of the 18 MCLs negative for p53 overexpression showed conformational changes by SSCP. For these 18 patients with MCLs that did not overexpress p53, the median survival was 63 months, compared with 12 months for the 5 patients with MCLs positive for p53 overexpression (P < .001). These results suggest that p53 overexpression in MCL with t(11;14)(q13;q32) may serve as a marker of poor prognosis.

Homozygous deletions and loss of expression of the CDKN2 gene occur frequently in head and neck squamous cell carcinoma cell lines but infrequently in primary tumors

Deletion of 9p21-22 is a common genetic alteration in dysplastic, in situ, and invasive head and neck squamous cell carcinoma (HNSCC). However, a candidate tumor suppressor gene (TSG) at this site has thus far not been identified in HNSCC. We report homozygous deletion of the recently identified multiple tumor suppressor I (MTSI)/cyclin-dependent kinase-4-inhibitor (CDKN2) gene mapped to 9p21, which encodes the p16 protein, a regulator of cyclin-dependent kinase 4, in six of 16 HNSCC cell lines. We also show absence of the CDKN2 mRNA in all cell lines with CDKN2 deletion as well as in an additional two cell lines without deletion. Overall, we have identified 9p abnormalities in 12 of 16 (75%) cell lines, at least nine of which involved CDKN2. We further demonstrate that the CDKN2 deletion in HNSCC is located within a previously described region of allelic loss between D9S171 and IFNW, which spans a 4 cM region of 9p. However, examination of 36 primary tumors revealed genetic alterations in only seven of 36 (19%) tumors. These results suggest that genetic alterations at CDKN2 are frequent in HNSCC cell lines, but the role of this gene in primary tumors is less compelling. CDKN2 does not appear to be the only TSG on 9p21 in HNSCC, and our results suggest that another region of deletion exists proximal to the IFNW locus.

Genetic alterations at 5p15: a potential marker for progression of precancerous lesions of the uterine cervix

BACKGROUND

Development of uterine cervical cancer is preceded by preneoplastic proliferative changes in the cervical epithelium called "intra-epithelial neoplasia" or "dysplasia." The genetic basis of the origin and progression of such preneoplastic lesions is not known. By analysis of carcinomas for loss of constitutional heterozygosity (LOH), we have previously shown a high frequency of allelic loss in the short arm of chromosome 5 (5p), suggesting loss of a candidate tumor suppressor gene located in 5p and associated with the development of this tumor.

PURPOSE

To further understand the role of genetic alterations that affect 5p in cervical carcinogenesis, we evaluated the status of microsatellite polymorphisms at five loci mapped to 5p14-ter in precancerous and cancerous lesions.

METHODS

Biopsy specimens from two groups of patients were analyzed for genetic alterations affecting 5p. One group comprised 14 cases of precancerous lesions (i.e., dysplasias) and five cases of carcinoma in situ (CIS); the second group comprised 46 previously untreated patients with invasive carcinoma. Tumor and normal DNAs were analyzed by polymerase chain reaction for genetic losses and instability at five polymorphic microsatellite loci (D5S392, D5S406, D5S208, D5S117, and D5S432) mapped to 5p.

RESULTS

LOH was observed in 25 (55.6%) of 45 informative invasive carcinomas, one (20%) of five cases of CIS, and three (21%) of 14 precancerous lesions. Among the loci tested, D5S406 (5p15.1-15.2) exhibited LOH in 12 (48%) of 25 invasive carcinomas, one (33%) of three cases of CIS, and three (60%) of five precancerous lesions, suggesting this to be the site in 5p of the novel candidate tumor suppressor gene. In addition, replication error-type alterations were noted in the 5p14-ter region in six (13%) of 46 invasive carcinomas, two (40%) of five cases of CIS, and three (21%) of 14 precancerous lesions. Instability affected D5S406 in eight (66.7%) of 12 instances that showed microsatellite instability.

CONCLUSION

These observations suggest that allelic loss and microsatellite instability in the region of D5S406 may play a role early in the development of cervical carcinoma and identify the site of a candidate tumor suppressor gene. These genetic markers (allelic loss and microsatellite instability) may also define CIS and precancerous lesions at high risk for progression to invasive cancer.

IMPLICATIONS

The future molecular cloning of the candidate tumor suppressor gene at 5p15.1-15.2 may provide new insights into the genetic mechanisms of cervical carcinogenesis. Analysis and clinical follow-up of a large cohort of prospectively ascertained cases of precancerous lesions would help to validate the usefulness of these markers.

Loss of heterozygosity identifies multiple sites of allelic deletions on chromosome 1 in human male germ cell tumors

Cytogenetic analysis of human male germ cell tumors (GCTs) and derived cell lines revealed frequent deletions and rearrangements of chromosome 1. However, no detailed molecular analysis of these aberrations has thus far been performed. We undertook loss of heterozygosity (LOH) analysis utilizing a panel of 48 GCTs at 22 subregionally mapped polymorphic loci on both arms of chromosome 1. Eight probes, for which precise mapping data were unavailable, were subregionally mapped to specific regions by fluorescence in situ hybridization. Allelic losses were observed in 46% of cases on 1p and in 23% of cases on 1q. Teratomas showed higher frequency of allelic losses compared to embryonal carcinomas, yolk sac tumors, and seminomas, consistent with the results of our previous allelotype analysis, which showed overall higher genetic loss in teratomas compared to embryonal carcinomas. Our LOH study of chromosome 1 identified 4 sites of frequent deletions, 3 in the short arm (1p13, 1p22, and 1p31.3-32.2) and 1 in the long arm (1q32). Of these, 38.5% LOH at 1p22 (D1S16) identifies the site of a novel candidate tumor suppressor gene (TSG), possibly associated with GCTs. LOH at the remaining sites (1p13, 1p31.3-32.2, and 1q32) has also been reported in breast carcinomas, suggesting the involvement of TSGs common to both tumor types.

TP53 gene mutations and CCND1 gene amplification in head and neck squamous cell carcinoma cell lines

Mutations of the tumor-suppressor gene TP53 and amplification of CCND1 gene have been reported to occur frequently in head and neck squamous cell carcinomas (HNSQCC). In experimental systems, TP53 mutations have been shown to lead to genomic instability, including an increased propensity for gene amplification. We have examined 16 HNSQCC cell lines for the association between TP53 over-expression/mutation and CCND1 amplification. p53 over-expression was detected in 50% of the cell lines by immunohistochemistry using the monoclonal antibody (MAb) PAb1801. TP53 mutations were also detected in 50% of the cell lines by analysis of single-strand conformation polymorphism (SSCP) and DNA sequencing of exons 4 through 9. Six cell lines showed TP53 mutations and over-expression of the protein, 2 cell lines showed TP53 mutations but no p53 expression, and 2 cell lines showed over-expression of p53 protein but no TP53 gene mutations. CCND1 amplification was found in 38% of the cell lines by Southern blot analysis. Only 1 cell line showed both TP53 mutation and CCND1 amplification, whereas 7 of 8 cell lines with TP53 mutations had no CCND1 amplification. pRb expression was detected by Western blot analysis, and the level of pRb did not correlate with either CCND1 amplification or TP53 mutation. Our findings suggest that TP53 mutation and CCND1 amplification are common genetic alterations in HNSQCC and that the occurrence of either genetic event may be sufficient to abrogate normal cell cycle control.

Frequent allelic deletions and loss of expression characterize the DCC gene in male germ cell tumors

The DCC tumor suppressor gene has been shown to be frequently deleted or its expression reduced or absent in colorectal, gastro-intestinal, pancreatic, prostatic, and breast carcinomas, and glioblastomas. By allelotype analysis using the DCC-flanking polymorphic marker D18S5 we have previously shown that allelic deletions at 18q21 occur in 40% of male germ cell tumors (Murty et al., 1994). In order to further understand the role of DCC gene in germ cell tumorigenesis, we evaluated deletions by loss of heterozygosity (LOH) and mRNA expression by RT-PCR in tumor tissues and cell lines. Analysis of 61 paired normal-tumor DNAs using the probes D18S5, JOSH 4.4 (a polymorphism within the DCC locus) and a (CA)n polymorphism in an intron of DCC revealed that 45% of GCTs had allelic deletions. In addition, two homozygous deletions were found in the DCC gene among 91 (61 used in the LOH analysis and an additional 30) tumor DNAs when screened with the cDNA probes (pDCC 1.65, pDCC 1.9 and pDCC 1.0). By RT-PCR analysis of four normal testes, nine GCT cell lines and 14 tumor tissues, DCC gene expression was detected in all four normal testes, while four (45%) GCT cell lines and one (7%) tumor specimen showed lack of expression. In addition, DCC expression was highly reduced in three (21%) tumor tissues. The high frequency of LOH at 18q21 was characteristic of seminomas as well as all subsets of non-seminomas in primary as well as metastatic states. Frequent allelic loss in all histologic subsets, homozygous deletions, and loss of expression of DCC suggest that suppression of this gene's function is an early event in GCT development.

Allelotype analysis of cervical carcinoma

To identify the genetic events which may play a role in the development of cervical carcinoma, we performed a detailed allelotype analysis utilizing DNA from 53 primary tumors and corresponding normal cells and 57 polymorphic probes mapped to each of the chromosomal arms, excluding the short arms of the acrocentric chromosomes. Loss of heterozygosity (LOH) of > 25% was observed at sites on 11 chromosomal arms, which included 1q (26%), 3p (35%), 3q (31%), 4q (46%), 5p (53%), 5q (38%), 6p (28%), 10q (28%), 11p (42%), 18p (38%), and Xq (26%). The most frequent LOH was noted on 4q (ADH3) and 5p (D5S19), suggesting that loss of candidate tumor suppressor genes on these chromosomal arms may play a role in the development of cervical carcinoma. The two sites of deletions identified on 5p and Xq represent novel candidate tumor suppressor gene sites which have so far not been reported in any other tumor type. Human papilloma virus status did not correlate with any of the sites which showed frequent LOH. TP53 mutation analysis by single-strand conformation polymorphism analysis was performed in 17 tumors that either showed 17p deletions (TP53, D17S5, or D17S28) or were human papilloma virus negative. One of the 7 human papilloma virus-negative tumors, which also showed LOH at the D17S28 locus, had a mutation in exon 5. This study represents the first comprehensive genetic analysis of this cancer and identifies several novel features of significance to genetic etiology of cervical carcinoma.

Characterization of the promoter region of the gene for the rat neutral and basic amino acid transporter and chromosomal localization of the human gene

The promoter region of the rat kidney neutral and basic amino acid transporter (NBAT) gene has been isolated and sequenced. The major transcription initiation site was mapped by primer extension. The entire promoter region and a set of 5' deletions within it were expressed at a high level in LLC-PK1 cells using the luciferase indicator gene. Positive and negative regulatory elements in the promoter region were observed. A human genomic clone of the transporter was also obtained and was used to localize the NBAT gene at the p21 region of chromosome 2.

Allelic loss and somatic differentiation in human male germ cell tumors

The complex but poorly understood human male germ cell tumors offer unusual opportunities for the genetic analysis of malignant transformation and embryonal differentiation in a pluripotential stem cell lineage. Histologically, these tumors are divided into two major subgroups, seminomas which are characterized by inability to express embryonal differentiation, and non-seminomas which are characterized by ability to express embryonal as well as extra-embryonal patterns of differentiation. To understand the role of genetic factors in the development of these tumors and the regulation of differentiation expressed by them, we carried out a detailed allelotype analysis by the loss of heterozygosity assay. This analysis revealed frequent deletions in known tumor suppressor genes (RB1, DCC, NME), a number of previously described sites of candidate tumor suppressor genes (3p, 9p, 9q, 10q, 11p, 11q and 17p), as well as several novel sites (2p, 3q, 5p, 12q, 18p and 20p). Our results also showed that well differentiated teratomas exhibit a significantly higher level of allelic loss compared to the less differentiated embryonal carcinomas. In addition, certain loci and genes exhibited frequent non-random deletion in teratomas (D3S32, D3S42, D5S12, D10S25, D11S12, RB1, TP53, NME1, NME2, D17S4, D18S6 and D20S6) and embryonal carcinomas (IFNB, D9S27). Among these loci, the NME genes were notable for a high degree of genetic loss (> 70%) in teratomas. These results suggested that nonrandom loss or inactivation of certain genes may be associated with tumor development and loss or inactivation of other genes may be associated with somatic differentiation.

Replication error-type genetic instability at 1q42-43 in human male germ cell tumors

The replication error phenotype, recognized as microsatellite sequence alterations, has recently been suggested to be associated with hereditary nonpolyposis colorectal cancer and other types of sporadic tumors. We examined paired tumor-normal DNAs from 69 human male germ cell tumors for somatic instability at the 1q42-43 region. Analysis of a variable number of tandem repeats marker (D1S74) and 3 (CA)n type microsatellite loci (D1S235, D1S180, and angiotensinogen) revealed genetic alterations in tumor DNAs of 26 (38.2%) cases. The changes observed comprised rearrangements with D1S74 detected by Southern blot analysis in 4 of 55 (7%) cases; replication error-type alterations with D1S235, D1S180, and angiotensinogen in 12 of 66 (18.2%) cases; and loss of heterozygosity in 12 of 67 (17.9%) cases with the same probes. The microsatellite sequence alterations were more common in histological subsets other than teratomas, while the loss of heterozygosity was significantly more frequent in teratomas compared to other histologies. These results suggest that microsatellite instability and loss of heterozygosity at 1q42-43 may be unrelated genetic events which may play a role in germ cell tumor development.

Loss of heterozygosity and decreased expression of NME genes correlate with teratomatous differentiation in human male germ cell tumors

Embryonal carcinoma in the human male is a pluripotential germ cell tumor (GCT), which is suggested to further differentiate to teratoma which displays somatic differentiation representing all three germinal layers. In a panel of 37 GCTs we determined frequency of loss of heterozygosity (LOH) and the level of expression of nucleoside diphosphate kinase (NDPK) genes NME 1 and NME 2. The frequency of LOH in teratomas (86%) was found to be highly significant (P < 0.01) compared to embryonal carcinomas (17%). We also found that the NME encoded proteins are expressed at a 4-5 fold lower level in teratomas compared to embryonal carcinomas. These findings lead us to hypothesize that a critical level of NDPK may be necessary for suppression of aberrant somatic differentiation.

Transforming growth factor receptor gene TGFBR2 maps to human chromosome band 3p22

In this study, we map the chromosomal position of the gene that encodes the type II receptor of TGF-beta (HGM symbol TGFBR2), a multifunctional regulator of cell proliferation and differentiation. Using a full-length cDNA and a genomic probe in Southern blot analysis of a human x rodent somatic cell hybrid panel and by direct fluorescence in situ hybridization to normal metaphase chromosomes, we show that the TGFBR2 gene maps to 3p22.

ERBB2 (HER2/neu) oncogene is frequently amplified in squamous cell carcinoma of the uterine cervix

We evaluated a panel of 22 protooncogenes for amplification in 50 primary, untreated squamous cell carcinomas of the uterine cervix. The tumors studied belonged to clinical stages II and III; histologically, the majority of them were moderately to well differentiated. Amplification represented by 5 or more copies was observed for the genes MYCL1, SEA, CCND1, BCL1, and GLI in one case each (2%); HRAS in 2 cases (4%); and ERBB2 in 7 cases (14%). Amplification of ERBB2 ranged from 5 to 68 copies. In addition, 2 tumors with ERBB2 amplification showed additional restriction fragments suggesting possible mutation or rearrangement of the gene. The high incidence of ERBB2 amplification in cervical cancer suggests that this gene may play an important role in tumorigenesis.

Subregional mapping of 8 single copy loci to chromosome 6 by fluorescence in situ hybridization

We have subregionally mapped 8 independently derived probes which have been assigned to chromosome 6 (D6S61, D6S134, D6S149, D6S155, MACS, VIL2, IGF2R and PLG) by FISH. All the probes were mapped to the long arm of chromosome 6 except D6S61, which was assigned to the short arm at 6p25. The remaining probes were clustered at the 6q25-->q27 region except MACS which was mapped to 6q22.2.

Confirmation of Duffy blood group antigen locus (FY) at 1q22-->q23 by fluorescence in situ hybridization

The gene for the Duffy blood group antigen (FY) was previously assigned to the chromosome region 1q22-->q23 by linkage analysis. We confirm this localization by fluorescence in situ hybridization.

Subregional localization of 20 single-copy loci to chromosome 6 by fluorescence in situ hybridization

Although 338 genetic loci and 1 or more candidate tumor suppressor genes have been assigned to chromosome 6, the physical and genetic map of this chromosome is at a very preliminary stage. In this study, we have performed subregional localization of 20 single-copy DNA sequences previously assigned to chromosome 6 using the fluorescence in situ hybridization technique. One locus, D6S6, was localized at 6p12. Two loci, D6S160 and D6S32, were localized in proximal 6q, at 6q12 and 6q23.3, respectively. The remaining loci were clustered in two regions, 4 at 6q23.5-q25 (D6S33, D6S43, D6S85, MYB) and 13 at 6q26-q27 (D6S2, D6S21, D6S22, D6S25, D6S37, D6S39, D6S44, D6S48, D6S132, D6S133, D6S148, D6S170, D6S201). These data will aid in the eventual development of the physical map of chromosome 6.

Chromosomal localization and nucleoside diphosphate kinase activity of human metastasis-suppressor genes NM23-1 and NM23-2

Human metastasis-suppressor genes nm23-1 (NME1) and nm23-2 (NME2) are implicated in control of the metastatic potential of malignant cells. Using somatic cell hybrid analysis and fluorescence in situ hybridization we co-localized both genes to 17q21.3. The 17q21 region carries the locus responsible for early-onset familial breast-ovarian cancer and several other genes that are involved in tumorigenesis and differentiation and undergo frequent rearrangements during neoplastic development. Thus, our mapping places the NME genes in a region that may be subjected to multiple selection pressures. NME1 and NME2 genes were expressed as soluble proteins in a T7 bacterial expression system. Both proteins are independently active nucleotide diphosphate kinases and readily form intra- and intermolecular disulfide bonds. The biochemical properties of these proteins may explain the diversity of mature eucaryotic nucleoside diphosphate kinases.

Confirmation of 15q26.1 as the site of the FES protooncogene by fluorescence in situ hybridization

The FES oncogene was previously localized to human chromosome 15 by analysis of mouse x human somatic cell hybrids and to 15q26 by in situ hybridization of a radioactively labeled probe. In the present study, using fluorescence in situ hybridization, we have determined the precise map position of FES at 15q26.1.

Chromosomal localization of genes encoding the transcription factors, c-rel, NF-kappa Bp50, NF-kappa Bp65, and lyt-10 by fluorescence in situ hybridization

We have used fluorescence in situ hybridization (FISH) to perform precise chromosomal mapping of the genes encoding the transcription factors c-rel, NF-kappa Bp50, NF-kappa Bp65, and lyt-10. The previously published assignments of c-rel and NF-kappa Bp50 have been refined to specific bands. The map position of lyt-10, inferred from its isolation from a t(10;14)(q24;q32) translocation, has been confirmed. NF-kappa Bp65 has now been mapped to 11q13, a site of frequent involvement in aberration in multiple tumor types.

Analysis of BCL2 and MYC expression in non-Hodgkin's lymphomas by in situ hybridization: correlation with chromosome translocations

We have used an in situ hybridization method for analysis of expression of BCL2 and MYC on cytospun preparations of normal and malignant lymphoid cell lines and tissue sections of normal and malignant lymph nodes. The probes comprised 50-mer antisense oligonucleotides starting at the ATG codons of exon 3 of BCL2 and exon 2 of MYC. We studied the expression of these two genes in frozen tissue sections of biopsy specimens derived from normal and hyperplastic lymph nodes, B-cell lymphomas carrying the t(14;18)(q32;q21) and t(8;14)(q24;q32) translocations, and T-cell lymphomas with clonal chromosome abnormalities. While all proliferating cells expressed both genes, BCL2 expression was increased two- to threefold in follicular lymphomas with t(14;18) and MYC expression was increased two- to four-fold in high-grade lymphomas with t(8;14). These results are consistent with previous data on deregulated expression of these genes obtained from study of lymphoma cell lines carrying the relevant translocations.