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In order to identify helpful markers in the classification of mantle cell lymphoma, a morphological, immunohistochemical and molecular genetic analysis of 41 cases of NHL, originally referred to us as CC, ILL or IDL, was performed. We revised these lymphomas using the strict morphological criteria described in the updated Kiel classification and the more recently described criteria for MCL. The term MCL was used to designate the small lymphocytic B-cell NHL, previously referred to as CC or ILL/ IDL. This revision yielded 20 MCL, 8 CLL, 3 Cb/Cc, 1 CB, 6 IC and 3 MALT lymphomas. The presence of scattered histiocytes was seen in 90% of MCL and 5% of the other cases. No other morphological parameter, besides the used criteria, differentiated between MCL and similar small lymphocytic B cell lymphomas. Helpful immunohistochemical markers to distinguish MCL from similar small lymphocytic lymphomas were CD5+, CD10-, CD23- and Alkaline Phosphatase+. Large fields of dendritic reticulum cells, often in a loose and disrupted arrangement were seen in 82% of MCL and in 19% of the other lymphomas. Analysis with Southern blotting showed a rearrangement in the BCL-1 locus in 12/20 cases of MCL but not in the other 21 lymphomas. Although very specific for MCL, Southern blotting to detect BCL-1 rearrangements is, due to the large number of probes necessary, not of great help in daily practice for routine diagnostic purposes. We conclude that using strict morphological criteria, the diagnosis MCL can be made reliably and that immunophenotyping is helpful in supporting the diagnosis.

11q13 amplifications have been found in several cancers, including bladder tumours. However, the biological significance of this genetic alteration is not yet fully understood. To get more insight into the role of 11q13 amplification in bladder tumour development, we have studied the level of amplification and expression of 4 (protoonco)genes lying within the amplicon; cyclin D1, FGF3, FGF4 and EMS1 DNA amplification was found in 5/46 tumours. There was no correlation between amplification and clinico-pathological data. No expression of FGF3 and FGF4 was detected whereas both cyclin D1 and EMS1 were expressed at higher level in tumours with amplifications. Thus cyclin D1 and EMS1, but not FGF3 and FGF4, are likely to play a pathogenic role in the 11q13 amplification in bladder cancer. However, amplification is not the unique way of activation of these genes. Indeed, in situ hybridisation and Northern blot analysis have shown that most bladder tumours have a fair to high expression of cyclin D1 and EMS1 in contrast to normal urothelium with a moderate expression. Interestingly, a trend towards higher expression occurs in superficial versus invasive tumours (8.8 +/- 2.0 versus 1.9 +/- 0.4; P approximately equal to 13% for cyclin D1 and 4.5 +/- 1.4 versus 2.0 +/- 0.4; P approximately equal to 8% for EMS1). Moreover, the 9 tumours with low expression are all highly malignant, leading to the hypothesis that the tumours developing through a cyclin D1/EMS1 independent pathway are more aggressive.

Purpose: From a population-based non-Hodgkin's lymphoma (NHL) registry, 41 patients with mantle cell lymphoma (MCL) -- a recently defined distinct B-cell NHL -- were selected and compared with patients with low- or intermediate-grade NHL from the same registry., Patients and Methods: The incidence and behavior of MCL in the area of the Comprehensive Cancer Center West (CCCW) from 1981 to 1989 were analyzed. Age, performance, tumor bulk, extranodal localization, stage, response to therapy, and survival were registered. Expression of cyclin D1 protein and Ki-67 were measured in 29 patients., Results: MCL made up 3.7% of NHLs. The median age was 68 years, and the male-to-female ratio was 1.6:1. Seventy-eight percent presented with stage IV, with the majority having bone marrow involvement. The complete response (CR) rate was 32% (13 of 41), with a median duration of 25 months. The median overall survival time was 31.5 months. The International Prognostic Index identified five patients with a low-risk score and a median survival time of 93+ months. In 23 of 29 patients, cyclin D1 overexpression was present, without any relation to overall or disease-free survival. In contrast, a proliferative index less than 10% was significantly related to a better overall survival time (50 v 24 months)., Conclusion: MCL is a disease of the elderly, who present with widespread disease and with a poor response to therapy. Although it harbors features of an indolent NHL, it behaves clinically as an aggressive NHL with a short overall survival time.

Background: Previous results suggested increased mRNA expression of CCND1 in hairy cell leukemia (HCL). The CCND1 gene is involved in the t(11;14)(q13;q32) chromosomal rearrangement, a characteristic abnormality in mantle cell lymphoma (MCL). We and others reported that, in contrast to other B-cell lymphomas, almost all MCL have over-expression of the CCND1 gene with a good correlation between RNA and protein analysis. Recent studies showed that overexpression of the cyclin D1 protein can be easily detected by immunohistochemistry (IHC) on formalin-fixed, paraffin embedded tissues., Patients and Methods: To investigate whether the CCND1 gene is involved in HCL, we performed IHC on a series of 22 cases using formalin-fixed paraffin embedded splenectomy specimens. For IHC the sections were boiled in citrate buffer. The presence of rearrangements within the BCL-1 locus and the CCND1 gene was analyzed in 13 of 22 cases by Southern blot analysis using all available break-point probes. Expression of CCND1 was analyzed at the mRNA level (Northern blot) and protein level (IHC)., Results: Overexpression of the cyclin D1 protein using IHC was observed in all cases, with strong expression in 5 cases. Pre-existing B- and T-cell areas of the spleen did not express significant levels of the cyclin D1 protein. Seven of 9 cases analyzed by both IHC and Northern blotting showed overexpression of the CCND1 gene with both methods. No genomic abnormalities were observed in any of the 13 cases studied by Southern blot analysis. Additionally, no 11q13 abnormalities were detected by banding analysis of 19 of 22 cases., Conclusions: The elevated levels of CCND1 mRNA and protein in conjunction with the absence of overt rearrangements within the BCL-1 locus distinguish HCL from MCL and other B-cell malignancies. This suggests that activation of the CCND1 gene in HCL is due to mechanisms other than chromosomal rearrangement.

Rearrangements within the chromosome 11q13 region are frequent in hematologic malignancies. 50% of 75% of mantle cell lymphomas (MCLs) carry a translocation t(11;14) (q13;q32). Using Southern blot analysis, a BCL1 breakpoint can be detected in approximately 50% of MCLs. It is not known whether other MCLs harbor also breakpoints at 11q13. Breakpoints in this region not involved in t(11;14), are detected in chronic lymphocytic leukemia and acute myeloid leukemia. To detect and localize breakpoints at 11q13 more accurately, we have developed fluorescence in situ hybridization using two probe sets of differently labeled cosmids, symmetrically localized at either side of the major translocation cluster of BCL1. These probes span a region of 450 to 750 kb. We applied this assay to a series of hematologic malignancies with 11q13 abnormalities identified by classical cytogenetics. All four samples with a t(11;14) (q13;q32) showed dissociation of the differently colored signals in metaphase and interphase cells, thereby indicating a chromosomal break in the region defined by the probe sets. The frequency of abnormal metaphase and interphase cells was comparable with that observed in any of the 13 malignancies with other chromosomal 11q13 abnormalities, indicating that these chromosomal breaks occurred outside the 450- to 750-kb region covered by the probes. One patient showed triplication and one patient showed monoallelic loss of this region. The current data show that double-color fluorescence in situ hybridization is a simple and reliable method for detection of the t(11;14)(q13;q32) in interphase cell nuclei and that is can be used to distinguish this translocation from other 11q13 rearrangements in hematologic malignancies.

Mantle cell lymphoma (MCL) is a clinicopathologic entity that is difficult to diagnose on histopathologic criteria. Approximately 50% to 70% of MCL contain a t(11;14)(q13;q32) translocation involving the cyclin D1 gene. Irrespective of this rearrangement, almost all MCL show overexpression of the cyclin D1 gene at the mRNA level. Other B-cell non-Hodgkin's lymphomas (NHL) do not show this rearrangement or overexpression of cyclin D1. We developed an immunohistochemical assay to detect overexpression of the cyclin D1 protein on conventional formalin-fixed, paraffin-embedded biopsies using the well-defined monoclonal antibody DCS-6. Expression in tumor cells was compared with expression of cyclin D1 in endothelial cells and fibroblasts. An exclusively nuclear staining pattern was observed. Moreover, expression was directly compared with the expression observed by immunoblot analysis with the same antibody, as well as with mRNA expression and with the occurrence of genomic rearrangements within the BCL-1 locus. Of 13 MCL that were analyzed by immunohistochemistry and immunoblot, 12 showed overexpression with both techniques, whereas no overexpression was observed in 39 other NHL. Of 13 additional MCL studied either by immunohistochemistry or immunoblot, 11 also showed overexpression. Two lymphomas morphologically indistinguishable from MCL but with an aberrant immunophenotype (CD5 negative, CD10 positive) both lacked overexpression of cyclin D1. These results underscore the significance of overexpression of the cyclin D1 protein as a specific marker for MCL. Detection of cyclin D1 overexpression on formalin-fixed, paraffin-embedded tissues using the DCS-6 monoclonal antibody can be applied for routine diagnostic purposes.

The presence of a t(11;22)(q24;q12) translocation is one of the characteristic features of the Ewing family of tumors. The detection of the fusion gene product by RT-PCR using primers at both sides of the breakpoints has been advocated as a diagnostic tool. By applying this technique appropriate internal controls are required. We found that the use of normal non-rearranged EWS mRNA as an internal control for RNA quality may lead to conflicting data. We obtained PCR products of the expected size for the normal EWS mRNA in both RNA and DNA samples, suggesting, the existence of one or more EWS pseudogenes. A 109 bp sequence at the 5' end of this PCR-product contained a correctly spliced exon junction and was 97% homologous to the EWS cDNA sequence. Similarly two such junctions were found in a 346 bp sequence of the 3' end, which was 89% homologous. Hence EWS should not be used as an internal control for the RNA quality in a RT-PCR based test for the presence of the translocation.

Amplification of oncogenes has been observed frequently in various human malignancies and might be of clinical relevance. In the last decade, the exploration of oncogene activation due to DNA amplification in cancer research has mainly focussed on three aspects: (i) the assessment of oncogene amplification as a prognostic marker for survival of cancer patients, (ii) the development of reliable methods for detection of tumors which harbor DNA amplification of oncogenes and (iii) the identification of the gene or genes responsible for the biological (prognostic) significance in tumors with DNA amplification and the characterization of these candidate proto-oncogenes that might help to elucidate their normal function and the role in tumor development. In this review, these three aspects will be highlighted with regard to DNA amplification of the chromosome 11q13 region. Chromosome 11q13 amplification has been found frequently in certain human malignancies; in cancer of the breast and of the head and neck region, amplification of this region is observed in 13 and 29% of tumors, respectively. The 11q13 amplification has been reported to be of clinical relevance in these cancers, since patients with this amplification show a poor clinical course of disease. The amplified 11q13 region is estimated to be 3-5 Mb in size and to harbor many (putative) genes. Recently, two candidate genes, CCND1 and EMS1, were identified which were both over-expressed in all carcinomas with an 11q13 amplification. Therefore, the activation of these genes might confer the selective advantage to these tumors. In addition, the characterization of these two novel genes sustained their potential role in carcinomas with 11q13 amplification.

In mantle cell lymphoma (MCL) a recurrent chromosomal rearrangement, t(11;14)(q13;q32), has been described. Most breakpoints have been detected within the 120 kb BCL-1 region, upstream of the cyclin D1 gene. To evaluate the association between BCL-1 rearrangement and expression of cyclin D1 in lymphoproliferative disorders, we analysed a series of 24 MCL, 56 other B-cell non-Hodgkin's lymphomas (NHL), 28 chronic B-cell leukemias, 18 hematopoietic cell lines and 10 normal lymphoid tissues at the RNA level. Hematopoietic cell lines with a known 11q13 translocation showed high expression of the 4.5 kb cyclin D1 transcript. Three B-cell lines without known 11q13 breakpoint showed low expression. We detected high expression in all (11/11) MCL with and in 11 out of 13 cases of MCL without detectable t(11;14) rearrangement. In three cases with a rearrangement at the 3' end of cyclin D1, two showed overexpression of the 1.5 kb transcript and one expression of an aberrant (3.0 kb) transcript. In other lymphoproliferative disorders, only 5/15 hairy cell leukemias, all without detectable t(11;14), and 5/8 B-cell leukemias suspected to be MCL in leukemic phase showed expression levels comparable to MCL, whereas no or only low expression were observed in 56 cases of other NHL, seven chronic B-cell leukemias and all (10/10) normal lymphoid tissues. Cell sorting experiments on fresh tonsils showed that this low expression was present in normal B-cells and not in T-cells. In contrast to other studies, our data indicate that cyclin D1 is expressed in many lymphoproliferative disorders and normal tissues, albeit at low levels. High levels of expression of cyclin D1 however is restricted to MCL and some hairy cell leukemias. We therefore propose that overexpression of cyclin D1 is a reliable marker for the classification of MCL.

Successive oncogenic steps are necessary to generate cancer. In many B-cell lymphomas, chromosomal translocations are considered to be an early oncogenic hit. We investigated whether the lymphoma-associated t(14;18) involving the BCL2 oncogene can occur outside the context of malignancy. To this end, we extensively screened blood cells from healthy blood donors by a very sensitive seminested polymerase chain reaction (PCR) for breakpoint junctions at JH1-5 on 14q32 and the major breakpoint region of BCL2 on 18q21. In each individual, mononuclear cells, granulocytes, flow-sorted B cells, and T cells were separately tested in five to seven independently performed PCRs (in total, 0.5 x 10(6) to 1.0 x 10(6) cells per fraction per individual). Amplification products that hybridized with an internal BCL2 probe and a JH probe were sequenced. Six of nine individuals harbored t(14;18) breakpoints. Translocations were restricted to B cells, with an estimated frequency of 1 in 10(5) or less circulating B cells. In total, 23 of 51 experiments on B cells were positive in contrast to 1 of 48 on T cells and 2 of 47 experiments on granulocytes. Consistent with the presence of 4.7% to 13.0% B cells in the mononuclear cell fractions, only very few (4 of 47) tests were positive in these fractions. Sequence analysis showed that four of six individuals harbored two to five unrelated t(14;18)-carrying B-cell clones. All breakpoints had a structure similar to that in follicular lymphoma. We propose that B cells with the t(14;18) translocation are regularly generated in normal individuals, but that only very few cells with the translocation will acquire the additional oncogenic hits necessary to establish the malignant phenotype.

The molecular genetic characterization of breast cancer has implicated or identified the involvement of at least 10 distinct gene alterations in the genesis or progression of this disease. The genes involved fall into three distinct classes, possibly reflecting their particular function in the tumorigenic process. First, there is a class of genes that is being amplified to various levels in clinically manifest breast cancer, most conspicuously c-neu, c-myc, and cyclin D1. Second, an as-yet unknown number of genes are targets for loss of heterozygosity or allelic imbalance events on a number of different chromosomes. Presumably, this reflects the presence of tumor suppressor genes located on chromosomes 3p, 6q, 16q, 17, and possibly a few additional chromosomes. Finally, at least three genes are implicated to confer heritable predisposition to breast cancer. These include the p53 oncogene on 17p, an as yet unknown gene on 17q, and at least one locus outside these regions. While a number of presently unknown genes will soon be identified and cloned, it is becoming evident from genetic mapping studies that the complexity of gene involvement in breast cancer has not yet seen its very limits. A comprehensive multidisciplinary molecular profiling of a large series of tumors of various histological subtypes may aid in understanding how the different genes may cooperate to cause breast cancer.

Objective: To establish the frequency and clinicopathologic correlates of 11q13 amplification in head and neck squamous cell carcinoma., Design: Retrospective clinicopathologic analysis., Setting: University and private cancer centers., Patients: Eighty-five patients with pathologically confirmed head and neck squamous cell carcinoma., Measurements: The degree of DNA amplification in each tumor was determined using chromosome 11q13 probes for the bcl-1 major translocation cluster, PRAD1/cyclin D1 (CCND1), the fibroblast growth factor gene HST1, EMS1, and glutathione S transferase, pi-1. The presence or absence of amplification was correlated with anatomic site, tumor stage, cytologic grade, histologic pattern, and mitotic activity., Results: Thirty-one patients (36%) showed a twofold to 10-fold amplification of 11q13 loci compared with the chromosome 11q23 ETS1 control probe. Twenty-nine of these encompassed bcl-1 through EMS1 loci; one sample showed only bcl-1 and PRAD1/cyclin D1 plus HST1 amplification, with another amplified at HST1 and EMS1 with minimal or no bcl-1 and PRAD1/cyclin D1 amplification. Amplification was significantly correlated with high cytologic grade, a diffusely infiltrative growth pattern, and with a hypopharyngeal primary site., Conclusions: Chromosome 11q13 amplification in head and neck squamous cell carcinoma is correlated with an aggressive histologic appearance and hypopharyngeal primary site and should be assessed in prospective clinical trials to determine its utility for treatment stratification and prognosis. Although PRAD1/cyclin D1 and EMS1 have been implicated in the pathogenesis of neoplasms with 11q13 amplification, rare cases with more limited amplicon size suggest that another relevant gene or genes may exist between these loci.

Centrocytic lymphoma (CC) and intermediately differentiated lymphocytic lymphoma (IDL) are B-cell non-Hodgkin's lymphomas composed of lymphocytes presumably derived from follicle mantle cells. In these lymphomas, a specific chromosomal translocation, t(11;14)(q13;q32), has been described. Previous studies suggested an association between t(11;14) chromosomal translocations and BCL-1 rearrangements. To evaluate the association between BCL-1 rearrangements and CC/IDL, Southern blot analysis was performed on a panel of 20 cases of CC/IDL, 22 cases of morphologically similar non-Hodgkin's lymphomas, 11 cases of chronic B-cell leukemias, and 2 cases of myelomas. We used various probes covering a considerable proportion of the 120-kilobase BCL-1 locus, and rearrangements in 50% of CC/IDL (10 of 20) were detected. In CC, all 4 breakpoints were located at the major translocation cluster (MTC). In contrast, in IDL, rearrangements were detected in 3 different cluster regions: 2 cases in the MTC, 2 cases with a breakpoint 24 kilobases outside the MTC, and 2 additional cases with breakpoints found 3 kilobases 5' of the first exon of the PRAD1/CCND1 gene, which is located 120 kilobases outside the MTC. In addition, one leukemia showed a breakpoint 63 kilobases outside the MTC. In all cases, there was comigration of the rearranged 11q13 fragment and the immunoglobulin heavy chain-joining gene complex, indicating a t(11;14)(q13;q32) chromosomal rearrangement. Our results show that Southern blot analysis is helpful to identify CC/IDL, but multiple breakpoints are present over a large region, and therefore, many probes are necessary to cover all breakpoints.

We previously proposed that a local duplication, not the loss of the subsequently amplified marker from its original site, might be the first step in gene amplification in human cells. It is important to investigate this issue in naturally occurring amplification and when copy numbers are relatively low. We have examined the location of single-copy and amplified 11q13 sequences in cell lines from human breast cancers and squamous cell carcinomas using fluorescence in situ hybridization both with a probe specific for the 11q13 amplifying region and with a chromosome 11-specific library. We show that in most cell lines the 11q13 amplicons are physically linked to chromosome 11 or to a chromosome derived from chromosome 11 by various rearrangements near the 11q13 region. In none of the cell lines were interstitial deletions of 11q13 detected. These results indicate that 11q13 amplification in human tumor cells generally does not involve deletion as the initial step. One cell line with chromosomally located amplified 11q13 sequences contained double minutes that harbored the MYC gene but no 11q13 sequences. This suggests that the genetic outcome and the mechanism of gene amplification are probably dependent on specific DNA sequences rather than on the origin of the cells.

We have previously identified two genes (EMS1 and PRAD1/cyclin D1) in the chromosome 11q13 region that are frequently coamplified and overexpressed in human breast cancer and in squamous cell carcinomas of the head and neck (E. Schuuring, E. Verhoeven, W.J. Mooi, and R.J.A.M. Michalides, Oncogene 7:355-361, 1992). We now report on the characterization of the 80/85-kDa protein that is encoded by the EMS1 gene. Amino acid sequence comparison shows a high homology (85%) to a chicken protein that was recently identified as a substrate for the src oncogene (H. Wu, A.B. Reynolds, S.B. Kanner, R.R. Vines, and J.T. Parsons, Mol. Cell. Biol. 11:5113-5124, 1991). Immunocytochemistry reveals that in epithelial cells, the human EMS1 protein is localized mainly in the cytoplasm and, to a very low extent, in protruding leading lamellae of the cell. However, in carcinoma cells that constitutively overexpress the protein as a result of amplification of the EMS1 gene, the protein, except in cytoplasm, accumulates in the podosome-like adherens junctions associated with the cell-substratum contact sites. The protein was not found in intercellular adherens junctions. Our findings, and the previously reported observations in src-transformed chicken embryo fibroblasts, suggest that the EMS1 protein is involved in regulating the interactions between components of adherens-type junctions. Since amplification of the 11q13 region has been associated with an enhanced invasive potential of these tumors, overexpression and concomitant accumulation of the EMS1 protein in the cell-substratum contact sites might, therefore, contribute to the invasive potential of these tumor cells.

DNA markers that map within the karyotypically defined band q13 on human chromosome 11 are amplified in a subset of mammary and squamous cell carcinomas. It is assumed that the amplified DNA includes a critical gene (or genes) whose overexpression provides a selective force in the development of the tumor. To help identify such genes, we have begun to construct a physical map of CpG islands in the region, making use of a squamous cell carcinoma cell line (UMSCC2) in which the 11q13 region is amplified 11-fold. We previously described the proximal end of this amplicon and the order of markers extending approximately 800 kb centromeric of the FGF3 locus (formerly INT2). We now report the use of chromosome jumping techniques to define additional CpG islands that lie distal to FGF3. These map within the amplified region in UMSCC2 cells and the most telomeric corresponds to the EMS1 gene. The data imply that the amplified DNA in UMSCC2 cells extends for over 1,500 kb and includes at least 7 potential genes. EMS1 and CCND1 (formerly PRAD1), the best candidates for the key gene on the 11q13 amplicon, are > or = 800 kb apart.

We have tested the use of several newly developed red, green, and blue fluorescent dUTPs in direct, multiple, and sensitive fluorescence in situ hybridization procedures. Among the ones tested, the tetramethylrhodamine-dUTP proved to give the best sensitivity; using conventional epifluorescence microscopy, cosmids could be visualized with a hybridization efficiency of 90%. Fluorescein-dUTP permitted visual cosmid detection with 50% efficiency, and, to the human eye, the green signals appeared less bright. With a blue fluorescent coumarin-labeled dUTP, only highly repetitive target sequences could be visualized directly. Imaging with a cooled CCD (charged coupled device) camera for prolonged integration times permitted localization of small targets using probes labeled with red and green fluorochromes. Visualization of a 1.8-kb single copy sequence with a rhodamine-labeled cDNA proved feasible. The strategy of identifying hybridization sites with multiple colors was successfully applied for multiple hybridizations to repetitive and unique targets, using the red and green labels directly and the biotin label indirectly with one layer of avidin-coumarin.

Amplification of the chromosome 11q13 region, which harbors the BCL1 region and the PRAD1, EMS1, HSTF1, and INT2 genes, was found in 36 (16%) of a series of 226 breast carcinomas. In the 153 patients with stage I-IIIa disease who had received no therapy prior to surgery and who were treated with curative intent, 11q13 amplification was associated with the presence of lymph node metastases (P less than 0.002). The presence of an 11q13 amplification was associated with a significantly shorter relapse-free survival (P less than 0.002) and a higher breast cancer-specific mortality (P less than 0.003). Stepwise multivariate analysis showed that, in addition to lymph node status, 11q13 amplification was the best predictor for short survival. Stratified log-rank analysis indicated that, within the group of lymph node-positive breast cancer patients, 11q13 amplification identifies a subgroup at high risk.

DNA amplification involving markers on human chromosome band 11q13 is a consistent feature of several major cancers, notably adenocarcinoma of the breast and squamous cell carcinoma of the head, neck, lung, and esophagus. Since the presence of the amplification may be clinically significant, by defining a subset of patients at increased risk, it is important to establish which of the several genes on the amplified DNA provides the selective force. Here we describe a physical map of the centromeric end of the amplified DNA as it exists in a particular squamous carcinoma cell line (UMSCC2) and establish an unambiguous order for several known markers in the region, including pMS51/D11S97, pHB159/D11S146, BCL1, PRAD1/D11S287, HSTF1/FGF4 and INT2/FGF3. Significantly, PRAD1 is within 120-150 kb of the BCL1 translocation breakpoint and the data identify a new CpG island (D11S814) between PRAD1 and HSTF1. The ordering of the HSTF1 and INT2 genes and the clustering of CpG islands in the region have important implications in assessing whether the frequently observed amplifications at 11q13 are centered on one or more genes.

Amplification of the chromosome 11q13 region is frequently found in human breast cancer and in squamous cell carcinomas of the head and neck, and has been associated with an unfavourable clinical course of disease. The known oncogenes within the amplified 11q13 region, INT2 and HSTF1, are rarely expressed in these tumours, indicating that another, hitherto unidentified, gene or genes confer(s) the biological (prognostic) significance to the amplification of the 11q13 region. To identify the gene or genes, we have constructed a cDNA library from a cell line with an 11q13 amplification and have performed differential cDNA cloning using [32P]dCTP-labelled cDNAs from human squamous cell carcinoma cell lines with and without an 11q13 amplification. We isolated two cDNA clones, U21B31 and U21C8, which recognize two genes amplified and overexpressed in cell lines harbouring an 11q13 amplification. In breast carcinomas and in squamous cell carcinomas amplification of both the U21B31 and the U21C8 gene was found in most tumours with an amplification of the 11q13 region, despite the large distance between both genes. Sequence analysis of the U21C8 cDNA clone revealed no homology to known genes; we call this gene EMS1. The U21B31 cDNA clone corresponded to the 3' end of the PRAD1 proto-oncogene, recently cloned from a parathyroid adenoma. Both gene products are of interest as potential markers to identify tumours with an 11q13 amplification.

From a single spontaneous feline mammary carcinoma, two subpopulations of epithelial tumor cells have been isolated. The variant cells were established as cell lines designated K248C and K248P. DNA ploidy analysis showed that the two cell lines represented cell populations already present in the original tumor. Chromosome analysis confirmed the feline origin of K248C and K248P and demonstrated that in addition to unique marker chromosomes characteristic for each cell line, both cell lines had several marker chromosomes in common. These data suggest that the two cell populations arose from a hypothetical single ancestor which diverged during tumor progression. The K248C and K248P cell lines differed from one another with respect to their tumorigenicity in athymic mice and epidermal growth factor (EGF) receptor content. The K248C cells were highly tumorigenic as indicated by a short latency period and high take rate. The K248P cells were poorly tumorigenic. Southern blot analysis revealed that the K248C cells contained an amplified EGF receptor gene that was accompanied by elevated levels of EGF receptor RNA and protein. The K248C cells were growth inhibited in vitro at EGF concentrations that stimulated growth of K248P cells. The amplification of the EGF receptor gene could be detected only in DNA derived from K248C cells at high passage numbers and not in DNA derived from the original tumor and K248C cells at low passage numbers. These data suggest that amplification of the EGF receptor gene occurred during establishment of the K248C cell line.

Approximately 15 to 20% of primary breast cancers and an even higher proportion of squamous cell carcinomas of the head and neck show amplification of DNA markers on band q13 of human chromosome 11. However, known genes within the amplified region, such as the FGF-related oncogenes INT-2 and HST-1, are very rarely expressed in these tumors. Here we show that another candidate oncogene, designated D11S287, implicated in the pathogenesis of parathyroid adenomas, is also amplified in breast cancers. Significantly, it is consistently coamplified with INT-2 and HST-1 in 36 out of 202 primary tumors, including one case in which the amplified unit did not encompass the translocation breakpoint marker BCL-1. This implies that D11S287 is on the same side of the breakpoint as INT-2, and pulsed-field gel electrophoresis indicates that D11S287 is less than 250 kb from the BCL-1 marker. Since D11S287 RNA was present at elevated levels in a group of tumors and cell lines in which the 11q13 region is amplified, it may be the key oncogene on this amplified unit, and could also be activated by BCL-1 translocations.

Wnt-1 (int-1) is a cellular oncogene often activated by insertion of proviral DNA of the mouse mammary tumor virus. We have mapped the 5' end and the promoter area of the Wnt-1 gene by nuclease protection and primer extension assays. In differentiating P19 embryonal carcinoma cells, in which Wnt-1 is naturally expressed, two start sites of transcription were found, one preceded by two TATA boxes and one preceded by several GC boxes. In P19 cells, a 1-kilobase upstream sequence of Wnt-1 was able to confer differentiation-specific expression on a heterologous gene. We have investigated how Wnt-1 transcription was affected by mouse mammary tumor virus proviral integrations in various configurations near the promoters of the gene. One provirus has been inserted in the 5' nontranslated part of Wnt-1, in the same transcriptional orientation, and has functionally replaced the Wnt-1 promoters. Wnt-1 transcription in this tumor starts in the right long terminal repeat of the provirus, with considerable readthrough transcription from the left long terminal repeat. Another provirus has been inserted in the orientation opposite that of Wnt-1 into a GC box, disrupting the first Wnt-1 transcription start site but not the downstream start site. Most insertions have not structurally altered the Wnt-1 transcripts and have enhanced the activity of the normal two promoters.

FRTL-5 cells were used to set up a thyroid tumor model system in C3H nu/nu mice. FRTL-5 tumors could be grown in nude mice provided serum TSH levels were elevated. Persistent TSH elevation was obtained by administration of Na131I, rendering the mice hypothyroid. After 4 weeks FRTL-5 cells were injected sc resulting in tumor growth within 2 weeks in eight out of eight mice. Although the tumors showed an apparently undifferentiated histology, lacking normal follicular structures, they were functional since the tumors were capable of concentrating [131]iodine, as demonstrated by nuclear imaging. From one of the tumors a new cell line was isolated (FRTL-5/T) that, like the parental FRTL-5 cell line, was TSH dependent for growth. In a control group of six euthyroid nude mice FRTL-5 tumor growth could not be obtained with one exception. After 3 months one animal developed a small tumor that grew rapidly thereafter. This tumor was easily transplantable in other euthyroid nude mice, showed an undifferentiated histology, and was nonfunctional, as it could not concentrate [131]iodine. From this tumor two cell lines were derived: one cultured in the presence of TSH (FRTL-5/TP) and one in the absence of TSH (FRTL-5/TA). Both cell lines were found to be TSH independent for growth. The cell lines were analyzed for TSH responsive functions and TSH receptor expression. Responsiveness to TSH in FRTL-5/T and the parental FRTL-5 cell line were similar for most thyroid specific functions tested. However, FRTL-5/T was less sensitive than FRTL-5 for TSH induced [3H]thymidine incorporation. Both cell lines had two classes of TSH binding sites with high and low affinity respectively, as determined by Scatchard analysis. FRTL-5/TP and FRTL-5/TA were both able to grow in TSH free medium and were nonresponsive to TSH in vitro, as tested for [3H]thymidine and [3H]uridine incorporation, iodine uptake, thyroglobulin iodination, and thyroglobulin secretion. This correlated with an approximately 100-fold decreased number of TSH binding sites compared to FRTL-5. The latter was caused by a complete absence of low affinity binding sites, whereas high affinity receptors were still detectable. The FRTL-5/TA cell line was the least differentiated one as thyroglobulin mRNA was detectable in only minute amounts and thyroid peroxidase expression could not be measured. These in vivo selected FRTL-5 cell lines offer a suitable model to investigate several aspects of TSH responsiveness, including signal transduction and postreceptor events, thyroid differentiation, and thyroid tumorigenesis.

The int-1 mammary oncogene is frequently activated by proviral insertion in mouse mammary tumors. To characterize the target cell for the oncogenic action of int-1, we have isolated permanent cell lines with distinct morphologies and differentiation characteristics, starting from a tumor with a rearranged int-1 gene. Polygonal cells had retained many differentiation markers of epithelial cells and produced adenocarcinomas upon transplantation in syngenic mice. Sphere-forming-cuboidal cells are poorly differentiated and produced anaplastic tumors. Cuboidal and elongated cells were negative for epithelial markers. Cuboidal cells were poorly tumorigenic, but elongated cells produced highly malignant sarcoma-like tumors. In all lines, the int-1 gene was identically rearranged due to insertion of proviral DNA of the Mouse Mammary Tumor Virus, but the expression of int-1 varied with the state of differentiation of the cells. Polygonal cells contained relatively high levels of int-1 RNA, which were not influenced by steroid hormones. In the sphere-forming-cuboidal cells, expression of int-1 was low but inducible by dexamethasone. In the cuboidal and elongated cells no expression of int-1 was detectable, showing that the continued expression of int-1 was not required for progression to more malignant cells. By immunoprecipitation, two int-1 protein species, of 42 and 40 kD were identified in polygonal and in sphere-forming-cells but not in the culture media.

Increased expression of mouse mammary tumour virus (MMTV) is associated with hyperplastic alveolar growth and subsequent development of mammary cancers in the mouse. The expression of this virus is repressed when mammary tumour cells undergo sarcomatous transformation. We have demonstrated that a spontaneous progression of mouse mammary adenocarcinoma cells into highly malignant cells with the transformed phenotype is accompanied by an increased expression of transforming growth factors alpha and beta (TGF alpha and TGF beta), as well as a decreased expression of MMTV. Mouse mammary adenocarcinoma cells transformed with activated ras oncogene also expressed high levels of the transforming growth factors and a low level of MMTV. Thus a reverse correlation exists between the increased expression of the transforming growth factors and a low level of expression of MMTV. Mouse mammary cells that express high levels of MMTV when treated with exogenous TGF alpha and TGF beta 1 showed a down regulation of MMTV expression in response to TGF beta 1 but not to TGF alpha. These results demonstrate that the repression of MMTV expression in mouse mammary tumour progression may be due in part to an increased expression of TGF beta.

The RAC cell lines are derived from a mammary tumor induced by the mouse mammary tumor virus (MMTV). Polygonal cells have retained many characteristics of epithelial cells and induce adenocarcinomas; cuboidal cells are poorly tumorigenic; and elongated cells produce highly malignant sarcoma-like tumors. MMTV proviral integrations, one of which has cis-activated the int-2 gene, demonstrated that the lines are clonal descendents from a single tumor cell. Polygonal cells have a high constitutive expression of MMTV and contain int-2 RNA. In contrast, the cuboidal and the elongated cells show no detectable expression of int-2, even in the presence of glucocorticoid hormone. Transcription of MMTV in these cells is also low but can be stimulated by dexamethasone, albeit to levels lower than in polygonal cells. Thus, expression of int-2 seems to be caused by an enhancing activity on the MMTV provirus which is not dependent on steroid hormone and is specific for mammary tumor cells with epithelial characteristics. Progression in this cell system does not require sustained expression of int-2.

We are attempting to identify cellular oncogenes activated in mammary tumours by using the mouse mammary tumour virus (MMTV) as an insertional mutagen. MMTV, a retrovirus lacking a host cell-derived viral oncogene, induces adenocarcinomas of the mammary gland after a long latency period. The tumours are clonal outgrowths of cells carrying one or more integrated MMTV proviral copies. We have cloned an integrated MMTV provirus with its adjacent chromosomal DNA and we have established that the insertion site was part of a domain of the mouse genome in which MMTV proviruses are inserted in many different tumours. A gene within this domain, called int-1 is transcriptionally activated as a consequence of proviral integration. We have proposed that int-1 is a cellular oncogene for mammary tumours. Proviral activation of int-1 occurs in cis, over distances of up to 10 kilobases and is presumably caused by the transcriptional enhancer present on the MMTV long terminal repeat. The putative int-1 mammary oncogene has been subjected to a detailed structural analysis by S1 mapping and DNA sequencing. It encodes a protein that is highly conserved between mouse and man. The protein encoding domain of the gene is distributed over four exons which are demarcated by the insertion sites of MMTV proviruses found in mammary tumours. Some insertions, however, are found in the transcriptional unit of int-1, but these insertions do not disrupt the protein encoding domain of the gene.

In mouse embryos, the int-1 proto-oncogene is transiently expressed in areas of the developing neural system. Retinoic acid-treated P19 embryonal carcinoma cells have often been used as an in vitro model for the molecular basis of neural development. We shown here that int-1 is transiently expressed in differentiated P19 cells. The time course and retinoic acid dose dependence of int-1 expression suggest that the gene is specifically expressed during early neural differentiation. P19 cells may be a useful model to assist in the study, at the cellular level, of the role of int-1 in neural development.