Enamel remineralization on teeth adjacent to Class II glass ionomer restorations

We describe a patient with mantle cell lymphoma (MCL) associated with BCL6 gene rearrangement. MCL is a distinct subtype of non-Hodgkin's lymphoma characterized by CD5+, CD10-, CD20+, t(11;14)(q13;q32) and PRAD1/cyclin D1 overexpression. Although rearrangement of the BCL6 gene is the most frequent genetic change among diffuse lymphomas and some follicular lymphomas this is the first report of a patient with MCL associated with BCL6 rearrangement.     

Molecular analysis of 11q13 breakpoints in multiple myeloma

The t(11;14)(q13;q32) chromosomal translocation, which is the hallmark of mantle cell lymphoma (MCL), is found in approximately 30% of multiple myeloma (MM) tumors with a 14q32 translocation. Although the overexpression of cyclin D1 has been found to be correlated with MM cell lines carrying the t(11;14), rearrangements of the BCL-1/cyclin D1 regions frequently involved in MCL rarely occur in MM cell lines or primary tumors. To test whether specific 11q13 breakpoint clusters may occur in MM, we investigated a representative panel of primary tumors by means of Southern blot analysis using probes derived from MM-associated 11q13 breakpoints. To this end, we first cloned the breakpoints and respective germ-line regions from a primary tumor and the U266 cell line, as well as the germ-line region from the KMS-12 cell line. DNA from 50 primary tumors was tested using a large panel of probes, but a rearrangement was detected in only one case using the KMS-12 breakpoint probe. Our results confirm previous findings that the 11q13 breakpoints in MM are scattered throughout the 11q13 region encompassing the cyclin D1 gene, thus suggesting the absence of 11q13 breakpoint clusters in MM.     

BCL-1/cyclin D1 oncoprotein oscillates and subverts the G1 phase control in B-cell neoplasms carrying the t(11;14) translocation

In an effort to elucidate the biological role played by cyclin D1, a candidate BCL-1 oncogene, in human B-cell tumours carrying the t(11;14) translocation, we have studied the properties of this cyclin protein in a series of human lymphoid lines with rearrangements in the BCL-1 locus. The BCL-1/cyclin D1 protein was easily detectable in both immunocytochemistry and immunoblotting, its abundance grossly correlating with the mRNA levels. The cyclin D1 protein was localised predominantly to nuclei and there was a striking variation of staining intensity among the exponentially growing cells, reflecting the maximum level reached in mid/late G1 and the lowest level in S-phase. This characteristic mode of cell cycle-dependent oscillation was confirmed by three independent approaches, demonstrating that even upon rearrangement, the expression of cyclin D1 is regulated in a cyclical manner. Antibody-mediated and anti-sense oligonucleotide 'knockout' experiments revealed that the aberrantly expressed BCL-1/cyclin D1 protein is required for G1 phase progression of all four B-cell tumours with the BCL-1 rearrangement. Consistent with the proposed oncogenic role of this cyclin, our data demonstrate that the BCL-1 deregulation caused by chromosomal rearrangement leads to expression of a functionally active cyclin D1 protein which subverts the G1 phase control in the human B-cell tumours carrying the t(11;14) translocation.     

BCL-6 and other genomic alterations in non-Hodgkin's lymphoma (NHL)

This study reports on the frequency and disease association pattern of a number of gene rearrangements in a large panel of lymphoid tumours (n = 94). We detected the t(11;14) translocation, involving rearrangement of the BCL-1 locus, in 60% of mantle cell lymphomas. The BCL-2 gene, located at band 18q21, was rearranged in 42% of follicle centre lymphomas (FCL) and in 15% of diffuse large B-cell (DLBC) lymphomas. In this study, 80% of the c-MYC rearrangements were detected in aggressive diffuse lymphoma subsets but, interestingly, 9% of FCL showed involvement of t(8q24) translocation. In our study, rearrangements of the BCL-6 gene at band 3q27 were found in 31% of DLBC lymphomas. Interestingly, 50% of the BCL-6 rearrangement positive lymphoma cases had coexisting gene rearrangements involving all of the aforementioned gene loci. The molecular dissection of these genes will improve our understanding of the genesis of the diverse clinicopathological subtypes.     

Detection of the chromosomal translocation t(11;14) by polymerase chain reaction in mantle cell lymphomas

The t(11;14)(q13;q32) and its molecular counterpart, BCL1 rearrangement, are consistent features of mantle cell lymphoma (MCL). Rearrangement is thought to deregulate the nearby CCND1 (BCL1/PRAD1) proto-oncogene, a member of the cyclin G1 gene family, and thereby to contribute to tumorigenesis. We and others have previously shown that the BCL1 locus is rearranged in 55% to 60% of MCL patients and that, on chromosome 11, more than 80% of the breakpoints are localized within a 1-kbp DNA segment known as the major translocation cluster (MTC). We have determined the nucleotide sequence for a portion of the MTC region, and constructed chromosome 11-specific oligonucleotides that were in conjunction with a consensus immunoglobulin (Ig) heavy chain joining region (JH) primer used to perform the polymerase chain reaction (PCR) to amplify t(11;14) chromosomal junctional sequences in DNA from 16 MCL patients with breakpoints in the MTC region. 15 of the 16 breakpoints that occurred at the MTC region were amenable to PCR detection. The sizes of the amplified bands, the existence or not of a Sac I site in the PCR products, and nucleotide sequencing of the amplified DNA from four patients showed that the breakpoints share a remarkable tendency to tightly cluster within 300 bp on chromosome 11, some of them occurring at the same nucleotide. On chromosome 14, the breakpoints were localized within the Ig JH. Our findings indicate that a BCL1 rearrangement can be detected using this approach in roughly one half of the MCL patients. This has implications for both the diagnosis and the clinical management of MCL.     

Prevention of maternal and developmental toxicity in rats via dietary inclusion of common aflatoxin sorbents: potential for hidden risks

The chromosomal translocation t(11;14)(q13;q32) fuses the IGH and CCND1 genes and leads to cyclin D1 overexpression. This genetic abnormality is the hallmark of mantle cell lymphoma (MCL), but is also found in some cases of atypical chronic lymphocytic leukemia (CLL), characterized by a poor outcome. For an unequivocal assessment of this specific chromosomal rearrangement on interphase cells, we developed a set of probes for fluorescence in situ hybridization (FISH). Northern blotting was performed for analysis of the cyclin D1 expression in 18 patients. Thirty-eight patients, with either a typical MCL leukemic phase (17 patients) or atypical CLL with an MCL-type immunophenotype, i.e., CD19-, CD5+, CD23-/low, CD79b/sIgM(D)++, and FMC7+ (21 patients), were analyzed by dual-color interphase FISH. We selected an IGH-specific BAC probe (covering the JH and first constant regions) and a commercially available CCND1 probe. An IGH-CCND1 fusion was detected in 28 of the 38 patients (17 typical MCL and 11 cases with CLL). Cyclin D1 was not overexpressed in two patients with typical MCL and an IGH-CCND1 fusion. In view of the poor prognosis associated with MCL and t(11;14)-positive CLL, we conclude that this set of probes is a valuable and reliable tool for a rapid diagnosis of these entities.     

Characterization of t(11;14) translocation in mantle cell lymphoma by fluorescent in situ hybridization

Characterization of chromosome abnormalities in leukemia and lymphoma have contributed to the understanding of the molecular basis of these neoplastic diseases. In addition, specific chromosomal aberrations have acquired diagnostic or prognostic value. The t(11;14)(q13;q32) chromosome translocation has been detected in mantle cell lymphomas. However, possibly due to the limits of conventional cytogenetic analysis and the presence of different breakpoints at the molecular level, it is possible that the true percentage of association is underestimated. In our study, we used a yeast artificial chromosome, spanning the entire area where the rearrangements occur on chromosome 11q13, to detect the presence of translocations by fluorescent in situ hybridization experiments. We detected BCL-1 translocations in eight of eight patients with clinical and immunological features of mantle cell lymphoma, suggesting that the t(11;14) translocation is a critical event in the pathogenesis of MCL and may be a primary element for the diagnosis. Since this translocation is associated with poor prognosis, its detection may help to make a correct diagnosis as well as to evaluate residual disease, which is critical to plan a rational chemotherapy regimen.     

A DR17-restricted T cell epitope from a secreted Mycobacterium tuberculosis antigen only binds to DR17 molecules at neutral pH

Mantle cell lymphoma (MCL) was first described as a distinct biological entity on the basis of its association with the t(11;14)(q13;q32) resulting in over-expression of the cyclin D1 gene. Recognition of the morphological, immunophenotypic and clinical characteristics of MCL has enabled the accurate diagnosis of this entity and appreciation of its poor prognosis. Most published series of patients with MCL have used anthracycline-containing regimens. In contrast the British National Lymphoma Investigation (BNLI) group have treated 65 patients with MCL with non-intensive 'low-grade lymphoma' therapy. The median overall survival of 57 months and progression-free survival of 24 months compares favourably with the more intensively treated series. Although the disease was generally more aggressive than other low-grade lymphomas, some patients were asymptomatic and had indolent disease. When compared to 1853 patients with non-MCL low-grade lymphomas entered on the BNLI database, patients were found on average to be older (P=0.02), to have more extranodal disease (P<0.00001), and a higher proportion to have a raised ESR (P=0.02) and a low serum albumin (P=0.002). Multivariate analysis of significant prognostic markers in all BNLI low-grade lymphomas failed to identify MCL as an independent prognostic factor.     

Multiple breakpoints within the BCL-1 locus in B-cell lymphoma: rearrangements of the cyclin D1 gene

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.     

Phenoloxidase-dependent cytotoxic mechanism in ascidian (Styela plicata) hemocytes active against erythrocytes and K562 tumor cells

The distinction between mantle cell lymphoma (MCL) and other low-grade B-cell neoplasms is important because MCL has a more aggressive clinical course. In bone marrow biopsy specimens, this distinction can be especially difficult. We examined 70 bone marrow biopsy specimens involved by various B-cell lymphoid neoplasms to assess the utility of cyclin D1 immunostaining in distinguishing MCL from other B-cell lymphoproliferative disorders. We used a cocktail of two monoclonal anti-cyclin D1 antibodies and a heat- and sonication-induced epitope retrieval procedure. The neoplasms assessed included MCL (32 cases), small lymphocytic lymphoma/chronic lymphocytic leukemia (18 cases), follicular lymphoma (11 cases), hairy cell leukemia (5 cases), splenic marginal zone lymphoma (2 cases), and small lymphocytic lymphoma with plasmacytoid differentiation (2 cases). The diagnosis of MCL in bone marrow was confirmed by review of the original diagnostic biopsy specimens along with additional data, such as immunophenotypic or molecular studies. Most MCL (23/32; 72%) cases expressed cyclin D1 protein. In contrast, one case of small lymphocytic lymphoma/chronic lymphocytic leukemia (1/18; 6%) and one case of hairy cell leukemia (1/5; 20%) expressed cyclin D1 protein. These findings demonstrate that immunostaining for cyclin D1 protein expression is useful in distinguishing MCL from other B-cell lymphoid neoplasms in the bone marrow.     

Oncogene rearrangement in non-Hodgkin's lymphoma with a 14q+ chromosome of unknown origin

Southern blot analysis was performed with a panel of DNA probes to detect rearrangements of c-myc, bcl-1, bcl-2 and bcl-3 in 14 cases of B-cell non-Hodgkin's lymphoma (NHL) with a clonal cytogenetic rearrangement involving the chromosome 14q32 locus and no known donor chromosome [t(14;?)(q32;?)]. In our experience, 21% of all chromosomal abnormalities involving the 14q32 locus in B-cell NHL are of this type. We found oncogene rearrangements in five of the 14 cases: bcl-1 rearrangement on one mantle zone lymphoma, bcl-2 rearrangements in two follicular lymphomas, and c-myc rearrangements in two small noncleaved cell lymphomas. We conclude that a 14q32+ abnormality of unknown origin is a relatively frequent karyotypic finding in B-cell NHL. In one third of the cases, known oncogenes that have been previously described in reciprocal translocations involving the immunoglobulin heavy chain locus were shown to be involved in the 14q32+ abnormality. The translocations in the other cases are likely to have involved one of the above oncogenes with breakpoints not revealed by the probes employed, other known oncogenes, or oncogenes that have not yet been identified.     

Concurrent disruption of cell cycle associated genes in mantle cell lymphoma: a genotypic and phenotypic study of cyclin D1, p16, p15, p53 and pRb

Mantle cell lymphomas (MCL) are morphologically and immunophenotypically distinctive lymphoid neoplasms characterised by overexpression of cyclin D1. Recent studies have suggested that co-operating aberrations of cell cycle associated genes may provide a growth advantage to a tumour. To address this issue further, we investigated five typical and three aggressive (blastoid) MCL for alterations in the cell cycle regulating genes p15, p16, CDK4, Rb and p53. In 3/3 aggressive cases with cyclin D1 overexpression we found aberration of at least one additional gene. One case showed diminished expression of the retinoblastoma protein (pRb); one case harboured deletion of both p15 and p16; and one case exhibited both deletion of p16 and point mutation of p53. However, we also identified two typical cases which in addition to cyclin D1 overexpression exhibited diminished pRb expression and p15 and p16 hypermethylation, respectively. Our findings confirm and extend other recent investigations and indicate that co-operating genetic alterations of cell cycle-associated genes may contribute to the pathogenesis of MCL.     

The morphologic spectrum of non-Hodgkin's lymphomas with BCL1/cyclin D1 gene rearrangements

BCL1/PRAD1 gene rearrangements involving the cyclin D1 gene are a feature of about 70% of centrocytic/mantle-cell lymphomas (CC/MCL) but are identified in only a small proportion of other B-cell non-Hodgkin's lymphomas. Of 37 lymphomas found to have BCL1/cyclin D1 (PRAD1, CCND1) gene rearrangements, 30 fit the morphologic and immunophenotypic criteria for typical CC/MCL. Seven cases with morphologic features atypical for CC/MCL were identified. CD5+ monoclonal B cells were documented in all these cases. Six cases were subsequently stained for cyclin D1 protein, and all showed nuclear positivity. Five cases had variably sized foci of cells with moderately abundant pale cytoplasm resembling parafollicular/monocytoid B cells, marginal zone cells, hairy cells, or even proliferation centers. Transformed-appearing cells were also present in some lymphomas. In one case, striking follicular colonization created a markedly nodular growth pattern mimicking a follicular lymphoma. A sixth case had a marked predominance of small, round lymphocytes at some sites, mimicking a small lymphocytic lymphoma. Five of these six cases also had areas more typical of CC/MCL. The seventh case was a CD5-positive splenic marginal zone-like lymphoma (SMZL) with plasmacytic differentiation and circulating villous lymphocytes consistent with a splenic lymphoma with villous lymphocytes (SLVL). These cases illustrate the morphologic spectrum of small B-cell lymphoid neoplasms that have BCL1/cyclin D1 gene rearrangements and overexpression of cyclin D1. Despite the BCL1 translocation and cyclin D1 overexpression, the splenic lymphoma with plasmacytic differentiation was definitely not a CC/MCL and fit the clinicopathologic entity of SMZL/SLVL. The other six cases are best considered CC/MCL variants based on a combined morphologic, immunophenotypic, and genotypic evaluation. Genotypic or immunophenotypic studies to identify cyclin D1 rearrangements and overexpression, although not pathognomonic, are useful in recognizing these variant CC/MCL cases, which can mimic almost any of the other well-described but more indolent low-grade B-cell lymphomas and leukemias. Some of the variant CC/MCL cases had features in common with the CD5+ cyclin D1+ SMZL/SLVL, suggesting a possible relationship between these two otherwise distinct entities.     

Structure of Bcl-1 and IgH-CDR3 rearrangements as clonal markers in mantle cell lymphomas

Mantle cell lymphoma represent a clinicopathologically distinct entity of malignant non-Hodgkin's lymphoma (NHL) and are characterized by a specific chromosomal translocation t(11;14)(q13;q32) involving the cyclin D1 gene also designated as bcl-1/PRAD1 gene on chromosome 11 and the heavy chain immunoglobulin joining region on chromosome 14. We have established a PCR method to amplify t(11;14) junctional sequences in DNA from fresh frozen and paraffin-embedded tissue by bcl-1-specific primers in combination with a consensus immunoglobulin JH primer. A total of 65 cases histologically classified as mantle cell lymphoma (MCL) were analyzed for the presence of a t(11;14) translocation and monoclonal IgH-CDR3 rearrangements. From 26 patients with classical MCL and three cases with the anaplastic variant of MCL fresh frozen biopsy material was available for DNA extraction. We detected a bcl-1/JH rearrangement in 12 out of 29 samples (41%). In 36 cases paraffin-embedded lymph node tissue was the only source of DNA. In this material we found a bcl-1/JH rearrangement in six out of 31 samples with intact DNA (20%). To confirm the specificity of the PCR and to determine the bcl-1/JH junctional region sequences as clone-specific marker in individual patients we characterized the junctional DNA sequences by direct PCR sequencing in 16 cases. Interestingly we found that six bcl-1/JH junctions harbored DH segments in their N regions indicating that bcl-1/JH rearrangements can occur in a later stage of B cell ontogeny during which the complete VH to DH-JH joining or VH-replacement takes place. To investigate the suitability of IgH-CDR3 as sensitive molecular marker for those MCL patients in which a t(11;14) translocation can not easily be amplified, we additionally analysed 60 cases for the presence of monoclonally rearranged IgH genes by IgH-CDR3-PCR. A monoclonal IgH-CDR3 PCR product could be identified in 24 out of 29 fresh frozen samples (79%) whereas only 11 out of 31 samples (36%) with paraffin-derived DNA were positive. We demonstrate that automated fluorescence detection of monoclonal IgH-CDR3 PCR products allows the rapid and sensitive monitoring of minimal residual disease also in cases that lack a PCR amplifiable t(11;14) translocation. In combination with allele-specific primers the procedure may improve current experimental approaches for detection of occult MCL cells at initial staging and residual disease during and after therapy.     

Rearrangements of the BCL6 gene and chromosome aberrations affecting 3q27 in 54 patients with non-Hodgkin's lymphoma

Chromosome aberrations affecting 3q27 are among the most frequent non-random abnormalities in non-Hodgkin's lymphomas (NHL), especially the diffuse, large cell type. Recently, an association between BCL6 rearrangement and frequent extranodal lesions, rare bone marrow infiltration and a favorable clinical outcome was reported. We performed molecular studies of the BCL6 gene in 54 patients with NHL. Twelve patients (22%) with rearranged BCL6 genes were selected for histological, clinical, molecular, and cytogenetic studies. Ten of these cases were diffuse, large cell type lymphoma, one a follicular lymphoma, and one a mantle cell lymphoma (MCL). All cases were of the B-cell type and this is the first time a rearranged BCL6 gene has been found in an MCL. Cytogenetic data for 10 cases were available and the partner sites of the 3q27 translocation were determined in 7 of 10 patients. These locations were variable, including 6p21.3, 9p22, and 14q11 in addition to the immunoglobulin loci 14q32 (IGH), 2p12 (IGK), and 22q11 (IGL). The heterogeneity in partner sites is distinct from other lymphoma subgroups and may suggest that the genetic events are not uniform among patients with BCL6 rearrangements.     

Joint stress in inline skating--a biomechanical study

Mantle cell lymphoma (MCL) has been established as a clinicopathologic entity in 1991. A histopathologic and immunohistochemical study of 16 cases of MCL was performed in order to demonstrate differential diagnostic aspects. MCLs were composed of small and medium-sized B cells assuming the appearance of centrocytes. The growth pattern was diffuse in 9 cases and that of follicle mantle zone type within at least partially present nodular parts in 16 cases. The immunohistochemical staining for CD23 antigen was negative in tumour cells whereas the strong immunoreactivity of follicular dendritic cells (FDC) decorated residual FDC network. Seven cases of MCL were examined for the presence of translocation t(11;14)(q13;q32) using polymerase chain reaction. Despite histomorphological features compatible with a diagnosis of low-grade lymphoma, MCL has a worse prognosis and more aggressive behaviour than other types of small cell lymphomas, such as small lymphocytic lymphoma and follicle centre lymphoma.     

The PRAD-1/cyclin D1 oncogene product accumulates aberrantly in a subset of colorectal carcinomas

The PRAD-1/cyclin D1 proto-oncogene is localized on chromosome 11q13 and it is overexpressed in several tumour types as a consequence of gene amplification or chromosomal rearrangements. In this study, the abundance and patterns of cyclin D1 protein expression in normal/non-involved colon (n = 44), primary (n = 48) and metastatic (n = 9) colorectal carcinomas, and in a series of 4 colon cancer cell lines were investigated by immunochemical methods using the DCS-6 monoclonal antibody specific for cyclin D1. While examination of all normal colorectal tissue samples and 56% of the primary tumours revealed only weak to undetectable immunostaining signals, 23% of the primary carcinomas showed moderate and 21% showed strong aberrant accumulation of this cell-cycle regulatory oncoprotein. The immunohistochemical patterns in the secondary lesions were concordant with the matched primary tumours in all cases. The staining was nuclear both in the clinical specimens and in the colon cancer cell lines, in which the antibody-mediated knock-out experiments demonstrated a positive regulatory role of the cyclin D1 protein whose function was required for progression through the G1 phase of the cell cycle. These results indicate that the PRAD-1/cyclin D1 protooncogene may be deregulated in a significant subset of colorectal tumours, and warrant further analyses of such aberrations of the cyclin D1/retinoblastoma protein pathway to elucidate its potential involvement in the multistep pathogenesis of human colorectal cancer.     

Carotid arterial blood flow in the ovine fetus as a continuous measure of cerebral blood flow

Principles derived from a group of 46 ML of the mantle zone are presented: Mantle pattern of a ML and its cytological structure are mostly sufficient for positive basic diagnosis. Diffuse mantle zone ML need detection of BCL-1 and CD5 hyperexpression which are characteristic for small-cell and centrocytoid forms when compared with BCL-2 positive centrofollicular lymphomas. B monocytoid lymphomas from the parafollicular subgroup as well as plasmacytoid ML from the marginal subgroup retain faint BCL-1 positivity but lose CD5 positivity. That may results in attempt of problematic narrowing of mantle zone definition because of existence of the mixed cellularity forms of mantle zone ML. Nodular mantle zone ML are clinically recognized late and are unsensitive to treatment which is opposite to the original idea of their relative benignity. M-coding of mantle zone ML is very defective because the codes do not separate nodular (perifollicular) and diffuse variants.     

Dysregulated cyclin D1 expression early in head and neck tumorigenesis: in vivo evidence for an association with subsequent gene amplification

Cyclin D1 proto-oncogene is a key regulator of the mammalian cell-cycle acting at the restriction point in late G1. Amplification of the cyclin D1 locus, located on chromosome 11q13, as well as cyclin D1 protein overexpression have been reported in several human malignancies. The purpose of this study was to evaluate cyclin D1 gene copy status and protein expression during the multistep process of head and neck tumorigenesis, using a combination of fluorescence in situ hybridization and immunohistochemistry techniques. From 29 selected patients presenting with head and neck squamous carcinoma and whose tumor cytospins had been previously screened for presence (16 cases) or absence (13 cases) of amplification at the 11q13 band, we analysed 46 paraffin-embedded tissue specimens that demonstrated, besides the primary tumor, the presence of contiguous adjacent normal tissue and/or premalignant lesions. Of the 16 amplified cases, nine demonstrated a continuous progression from premalignant to invasive carcinoma and seven (77.7%) of these cases showed cyclin D1 gene amplification in premalignant lesions prior to development of invasive carcinoma. Increased cyclin D1 protein expression was observed in all 16 amplified tumors and five of the 13 (38.4%) non-amplified tumors. Interestingly, dysregulated cyclin D1 expression was also found in the premalignant lesions adjacent to all 16 amplified tumors, and it appeared to precede cyclin D1 gene amplification. In contrast no dysregulated expression was detected in the premalignant lesions of the non-amplified tumors. In conclusion, these findings provide strong evidence for early dysregulation of cyclin D1 expression during the tumorigenesis process and suggest that dysregulated increased expression precedes and possibly enables gene amplification.     

Cell cycle-related variation and tissue-restricted expression of human cyclin D1 protein

Recent evidence from genetic studies suggests that abnormalities of some of the members of the cyclin superfamily may be intimately associated with tumourigenesis, most likely through deregulation of the cell cycle control. In an attempt to elucidate the potential role of cyclin D1 (a gene located within the 11q13 amplicon and a candidate BCL-1, PRAD-1 oncogene) in the pathogenesis of human neoplasias, we have developed and characterized a novel monoclonal antibody specifically recognizing cyclin D1 protein in various assays including immunohistochemistry on frozen and paraffin sections. Using the DCS-6 antibody as a tool, we now show a characteristic cell cycle-dependent variation of the cyclin D1 protein in human cultured cells and report on the first immunohistochemical study of this G1 cyclin in a range of normal human tissues and breast carcinomas. Analysis of normal tissues revealed generally low levels of cyclin D1 protein, mainly restricted to the proliferative zones of some epithelial tissues, and the lack of its expression in several human tissues including lymph nodes, spleen, and tonsils. In contrast, pronounced overexpression/nuclear accumulation of cyclin D1 was found in 37 per cent of cases in a series of 35 primary ductal carcinomas of the breast. We conclude that the DCS-6 antibody provides a potentially useful tool for the establishment of simple methods suitable for verifying any diagnostic and/or prognostic value of this novel marker on large series of histological specimens and opens the way for biochemical, immunocytochemical, and immunohistochemical studies of the role played by cyclin D1 aberrations in human oncogenesis.