Peter Matthiesen

A 3-cM commonly deleted region in 6q21 in leukemias and lymphomas delineated by fluorescence in situ hybridization†

Deletions of the long arm of chromosome 6 (6q) are frequent chromosome aberrations in non‐Hodgkin lymphomas (NHLs) and acute lymphoblastic leukemias (ALLs). It is presumed that one or more tumor suppressor genes are localized on 6q. By means of fluorescence in situ hybridization (FISH), we attempted to detect and delineate deletions of 6q in leukemias and lymphomas. We performed FISH on 148 cases of lymphoma and acute leukemia using a panel of 36 YAC probes distributed from 6q12 to 6q27 and a centromeric probe of chromosome 6 as internal control. Deletions of 6q that included a 7‐cM commonly deleted region in 6q21 were detected in 59 patients who had B‐ and T‐cell low‐grade and high‐grade NHL and ALL. FISH with two YAC probes flanking this region was performed on an additional 97 cases of NHL and leukemia. Deletions in 6q21 were detected in an additional 21 cases. In five cases of high‐grade B‐ and T‐cell NHL and ALL, the deletion breakpoints were located within the commonly deleted region. To define the deletion breakpoints exactly and to narrow this region further, FISH was performed with six additional YAC probes that have been physically localized within this region. A 3‐cM (4–5 Mb) commonly deleted region in 6q21 was delineated. Our study suggests that this commonly deleted region harbors a putative tumor suppressor gene involved in the pathogenesis of both low‐grade and high‐grade NHL and ALL. Genes Chromosomes Cancer 27:52–58, 2000.

Frequent deletions of 6q23–24 in B-cell non-Hodgkin's lymphomas detected by fluorescence in situ hybridization

Deletions of the long arm of chromosome 6 (6q) are among the most frequent chromosome aberrations in malignant lymphomas and often occur as secondary changes in addition to typical translocations, such as t(14; 18). Using fluorescence in situ hybridization (FISH) with two YAC probes hybridizing to 6q23–24 and with the centromeric probe D6Z1 as internal control, we studied 31 cases of low‐grade and eight cases of high‐grade B‐cell lymphoma. Deletions of 6q23–24 were detected in 21 patients (56.8%) by FISH, compared to 13 patients (33.3%) by chromosome analysis. Deletions of 6q23–24 were found by FISH in 5 of 13 cases of small lymphocytic lymphoma, in 2 of 3 cases of mantle cell lymphoma, in 10 of 14 cases of t(14; 18) positive low‐grade follicular lymphoma, and in 4 of 8 cases of high‐grade follicular lymphoma. This study shows that deletions of 6q23–24 are more frequent in B‐cell lymphomas than previously suggested and that they can be detected more sensitively by FISH than by chromosome analysis. Contrary to previous reports indicating that the region 6q23–24 is preferentially deleted in low‐grade lymphomas without t(14; 18), our results indicate that deletions of 6q23–24 appear to be common in other pathological subsets of B‐cell lymphoma as well, especially in follicular lymphomas with t(14; 18). Genes Chromosom. Cancer 18:310–313, 1997.

Chromosome aberrations are restricted to the CD56+, CD3− tumour cell population in natural killer cell lymphomas: a combined immunophenotyping and FISH study

Natural killer (NK) cell lymphomas are a newly recognized entity of non‐Hodgkins lymphoma with a highly aggressive clinical course and strong association with Epstein‐Barr virus (EBV) infection. Although no recurrent chromosome aberrations have been identified in NK‐cell lymphoma, deletions of 6q and trisomy 7 have been described repeatedly in this type of lymphoma. In this study we attempted to determine the immunophenotypes of tumour cells with certain chromosome aberrations, i.e. deletions of 6q and trisomy 7, in three cases of NK cell lymphomas by means of combined immunophenotyping and fluorescence in situ hybridization (FISH). In all three cases clonal chromosome aberrations were detected only in CD56+ cells but not in CD3+ or CD5+ cells. However, not all CD56+ cells were shown to contain these chromosome aberrations. Double immunophenotyping combined with FISH confirmed that the chromosome aberrations occurred only in CD56+CD3− cells. This study indicates that chromosome aberrations in NK‐cell lymphomas are restricted to the CD56+, CD3− and CD5− cell population and that NK‐cell lymphomas are indeed derived from mature true NK cells and not from T lymphocytes.

DETECTION OF DELETIONS IN THE SHORT ARM OF CHROMOSOME 3 IN UNCULTURED RENAL CELL CARCINOMAS BY INTERPHASE CYTOGENETICS

PURPOSE Analysis of genetic alterations may facilitate the differential diagnosis of renal cell carcinoma (RCC) subtypes. For genetic classification, deletion of the short arm of chromosome 3 (3p), the hallmark of nonpapillary/clear cell RCC, is a major diagnostic criterion. Because of the limited routine applicability of cytogenetics and molecular genetic techniques we investigated interphase fluorescence in situ hybridization (FISH) for the detection of this aberration in RCC. MATERIALS AND METHODS Using seven chromosome 3 specific probes FISH was performed on isolated nuclei from 26 uncultured sporadic RCC. RESULTS Alterations of chromosome 3 were identified in 19 RCC (73%). Monosomy and/or 3p-deletions were observed in 15 of 19 (79%) non-papillary/clear cell RCC but not in other morphologic subgroups. The median percentage of cells in a specimen containing loss of 3p was 45%. Deletion mapping indicated that large deletions affecting different regions in 3p are predominant. Chromosomal region 3p24 was recurrently involved in all RCC with a deletion in 3p. CONCLUSION Interphase FISH for the detection of loss in 3p provides a sensitive and feasible method for the genetic classification of kidney tumors and the delineation of recurrently deleted regions in 3p.

Feasibility of simultaneous fluorescence immunophenotyping and fluorescence in situ hybridization study for the detection of estrogen receptor expression and deletions of the estrogen receptor gene in breast carcinoma cell lines

Abstract For the first time, combined immunophenotyping and fluorescence in situ hybridization (FISH) technique according to the ”fluorescence immunophenotyping and interphase cytogenetics as a tool for investigation of neoplasms” (FICTION) technique have been successfully applied in solid tumors. Thus, we were able to visualize the antigen expression of cells with chromosomal deletions of a tumor suppressor region directly. In six breast carcinoma cell lines, we investigated the correlation between estrogen receptor (ER) expression status and deletions of the estrogen receptor gene (ESR). To screen for deletions of the ESR gene, dual-color FISH was performed with a YAC (yeast artificial chromosome) probe containing the ESR gene and, as internal control, with a centromeric probe of chromosome 6. Deletions of the ESR gene were detected in four of six cell lines. For direct comparison of ER expression with the copy number of the ESR gene at the single cell level, immunophenotyping with mouse anti-human ER antibody was combined with FISH with the YAC probe containing the ESR gene according to the FICTION technique. There was no correlation between lack of or reduced ER expression and deletions of the ESR gene. One cell line with deletions of the ESR gene did express ER on the protein level, while another cell line without a deletion did not. Cells with deletions of the ESR gene were either ER expression positive or negative. The staining intensity of ER expression was not associated with the copy number of the ESR gene. Thus, this FICTION study unequivocally shows that deletions of the ESR gene are not the major cause of absent or reduced ER expression in breast carcinoma cell lines.

Detection of 6q deletions in breast carcinoma cell lines by fluorescence in situ hybridization

Abstract Dual-color fluorescence in situ hybridization was performed to detect the frequency and extent of 6q deletions in ten breast carcinoma cell lines. In five cell lines, the 6q deletions involved large regions extending from 6q12–q16 to 6q27, and in one the deletion extended from the region distal to YAC 751G10 at 6q25.1 to 6q27. In two cell lines, 6q deletions occurred only in cells with polysomy 6, indicating that such deletions might be secondary chromosomal aberrations and reflect late genetic changes in breast carcinomas. In addition, an overrepresentation of 6q21–q22.2 was detected in one cell line.

Deletions of Human Chromosome Region 6q23-24 in B-Lineage Neoplasias

Deletions of the long arm of chromosome 6 (6q) are among the most frequent chromosome aberrations in B-lineage leukemias and lymphomas and often occur as secondary changes in addition to typical translocations, such as t(14;18). Using fluorescence in situ hybridization (FISH) with two YAC-DNA probes hybridizing to human chromosome region 6q23–24 and with the centromeric probe D6Z1 as internal control, we studied 31 low-grade and 8 high-grade B-cell lymphomas. Deletions in 6q23–24 were detected in 21 cases (54%) by FISH, compared to 13 cases (33%) by chromosome analysis. Deletions in 6q23-24 were found by FISH in 5/13 small lymphocytic lymphomas, 2/3 mantle cell lymphomas, 10/14 t(14;18)-positive follicular lymphomas and in 4/8 centroblastic lymphomas, three of the latter carrying a translocation t(14;18). This study demonstrates that in B-cell lymphomas deletions in 6q23-24 are present more frequently than suggested hitherto and that they can be detected more sensitively by FISH than by chromosome analysis. In contrast to previous reports suggesting the region 6q23-24 to be preferentially deleted in low-grade lymphomas lacking the translo cation t(14;18), our results indicate that deletions in 6q23–24 appear to be also common in other pathological subsets of B-cell lymphomas, especially in follicular lymphomas carrying the translocation t(14;18).