Oncogene Probes Research Articles

Abstract 1757: Patterns of clonal chromosomal aberrations in invasive breast cancer compared to adjacent DCIS lesions detected by a ten-probe FISH panel

Abstract Ductal carcinoma in situ (DCIS) refers to lesions with malignant epithelial cells that have not invaded the surrounding stroma. These lesions are confined to the ducts of the breast. It is thought that DCIS represents a stage that precedes invasive ductal carcinoma (IDC). However the linkage between these two lesions is still obscure. In order to analyze the patterns of genetic alterations as an approach to understand the correlation between DCIS and IDC, we developed four panels of FISH probes consisting of a total of eight gene specific probes and two centromeric probes and conducted a systematic FISH evaluation of breast tumor specimens containing both lesions. The gene probes tested for oncogenes and tumor suppressor genes specific for breast tumorigenesis while the centromeric probes were included to reflect and adjust for the ploidy of the cells. Objectives Determine gain and loss patterns of the oncogene and tumor suppressor gene probes within DCIS and IDC Compare similarities in the genetic make-up of DCIS and corresponding IDC lesions from the same case Characterize clonal evolution from DCIS lesions to IDC The database of the “Breast Susceptibility Study” conducted at the Naval Medical Center, Bethesda, Maryland was searched for patients whose pathology reports were positive for breast carcinoma with neighboring DCIS. Archived paraffin blocks were analyzed by a pathologist for the presence of invasive cancer and DCIS. Representative areas were marked on thick sections. The material was micro-dissected and disintegrated using the Hedley method. The resulting single cell suspensions were cytospun onto slides. The best cytospin for each lesion was. hybridized with four FISH probe panels subsequently. An Imaging relocation software allowed us to assess the same cells for all four sets of probes. For each lesion, manual counting of 150-200 nuclei was performed and tabulated into an excel spreadsheet to allow analysis of signal patterns. In collaboration with NCBI, algorithms were developed to compare clonal patterns. Preliminary data show that there are often major clones both in the DCIS and the IDC that present strong similarities to each other. However, the clones can differ in specific gains or losses of the oncogenes and tumor suppressor genes tested. The signals depicted in the table represent an attempt to delineate major clones within the DCIS and IDC populations. This study will improve our understanding of the molecular events that are involved in the progression from pre-invasive to invasive cancer and may lead to the development of prognostic biomarkers that can predict this transition. Citation Format: {Authors}. {Abstract title} [abstract]. In: Proceedings of the 101st Annual Meeting of the American Association for Cancer Research; 2010 Apr 17-21; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2010;70(8 Suppl):Abstract nr 1757.

Molecular-cytogenetic Characterization of Non-Hodgkin's Lymphoma with Double and Cryptic Translocations of the Immunoglobulin Heavy Chain Gene

The present study aimed to characterize the clinical and molecular-cytogenetic features of non-Hodgkin's lymphoma (NHL) with double translocation of the immunoglobulin heavy chain (IGH) gene. G-banding analysis, fluorescence in situ hybridization (FISH) with the IGH (Cgamma and VH) and oncogene (c-MYC, BCL1, BCL2, and BCL6) probes, and long-distance polymerase chain reaction (LD-PCR) were performed on 6 patients with B-cell lymphoma, one with angioimmunoblastic T-cell lymphoma, and one with acute lymphoblastic leukemia (ALL) with B-cell phenotype. G-banding analysis detected two different 14q32 translocations, t(14,18) and add (14)(q32) in a patient with ALL. Two distinct partners of double IGH translocation identified by FISH were as follows: c-MYC + BCL2 in 3 patients, c-MYC + BCL1 in 2, c-MYC + BCL6 in one, BCL2 + 9q22 in one, and 1q21 + 6q27 in one. Colocalization of BCL1 and c-MYC probes was demonstrated in a patient with mantle cell lymphoma. LD-PCR detected c-MYC/Cmu, c-MYC/Calpha and BCL6/Cmu, and c-MYC/Calpha fusion in each one patient. Seven of 8 patients showed high serum LDH. Central nervous system and leukemic involvement was observed in 5 and 6 patients, respectively. Median survival time of patients with c-MYC/IGH translocation was 9 months. The results defined a clinical subset of B-cell lymphoma/leukemia showing extremely poor prognosis. C-MYC/IGH translocation is possibly an evolutionary alteration following the primary IGH translocation with BCL1, BCL2, or BCL6. Furthermore, FISH identified one novel (9q22) and one cryptic chromosomal breakpoints (6q27) involved in IGH translocation.

Investigation of c-myc and p53 Gene Alterations in the Tumor and Surgical Borderline Tissues of NSCLC and Effects on Clinicopathologic Behavior: By the FISH Technique

Genetic alterations on the primary tumoral tissues and surgical borderline tissues of 51 patients with NSCLC on which radiotherapy and chemotherapy had not been performed were analyzed by using the FISH method with locus-specific probes for p53 tumor suppressor gene and c-myc oncogene and centromere-specific probes for chromosome 17 and chromosome 8 on which these genes are located. P53 deletions were detected in 7 patients (13.7%), c-myc amplification in 4 patients (7.8%), monosomy 17 in 2 patients (3.9%) and trisomy 8 in 3 patients (5.8%), and a high level of polyploidy in tumoral tissues of 6 patients (11.7%). P53 deletion and c-myc amplification were found at surgical borderlines of 2 patients and 1 patient, respectively. Although both p53 deletion and c-myc amplification have low frequency at surgical border tissues, not only their detection is important for the follow-up of recurrency and metastasis, but it is also important for genetical and pathological staging. The results of this study show that c-myc amplification in NSCLC is related to the shortening of survival (p < 0.01). C-myc amplification and p53 deletion are also effective for the occurrence of metastasis (p < 0.05) and the effect of c-myc amplification in this matter is much higher than p53 deletion. The gain or loss of copy number of chromosome 8 and monosomy 17 show parallel effects with c-myc amplification and p53 deletion, respectively, on the clinicopathological behavior of tumors.

Spectrum of transforming sequences detected by tumorigenicity assay in a large series of human neoplasms.

We here summarize the analysis of 126 DNA samples from patients with hematopoietic neoplasias and solid tumors and from various tumor cell lines that were screened in the tumorigenicity assay. Thirty-eight samples were able to induce tumors after transfection in NIH/3T3 cells and injection into nude mice. Southern-blot analysis with a panel of oncogene probes revealed human ras genes in the vast majority of cases (25 N-ras, 2 K-ras, 1 H-ras) but also activated FGF4, dbl, ret and mas genes respectively. DNA samples from the 6 remaining transfectants were cloned into EMBL-3 phages and screened with a human specific repetitive Alu probe. Direct hybridization of a transfectant cDNA library allowed cloning of the ufo oncogene. Application of the exon-trapping technique to alu-positive phage DNA from the other transfectants enabled us to isolate tre, cot, B-raf, p85beta/HUMORF8 and a novel oncogene.

Amplification of the c-yes oncogene in canine mammary tumors.

Genomic DNAs of 14 mammary tumors were analyzed by Southern blot hybridization using a human c-yes-1 oncogene probe. The amplification was successful in half of the cases (7 adenocarcinomas). The degree of amplification was approximately 4-fold, and a high proportion was seen in malignant tumors. In addition, DNA polymorphism was detected in two adenocarcinomas.

Relationship between alkaline phosphatase levels, osteopontin expression, and mineralization in differentiating MC3T3-E1 osteoblasts.

We are using viral oncogene probes to study the pathways by which osteoblast-specific gene expression is induced in ascorbic acid-treated MC3T3-E1 cells. The 12S product of the adenovirus E1A gene binds directly to key cellular regulators and, as a result, represses tissue specific gene expression and blocks differentiation in a wide variety of cell types. The main cellular targets of the E1A 12S product are the pRB family and p300/CBP family. The p300 family appears to be the primary target for E1A-mediated repression of tissue-specific gene expression in a variety of cell types. We have generated MC3T3-E1 cell lines that stably express either the wild-type 12S product or a mutant that targets p300/CBP, but not the pRB family. Using these constructs to dissect osteoblast differentiation, we found that targeting of p300/CBP appears to be sufficient to repress alkaline phosphatase expression, although a low but functional level of expression can be maintained if the pRB family is not targeted as well. Induction of alkaline phosphatase expression and activity can be dissociated from expression of late-stage markers such as osteocalcin and osteopontin. Surprisingly, cell lines exhibiting severe repression of alkaline phosphatase activity differentiate to a mineral-secreting phenotype much like normal MC3T3-E1 cells. Osteopontin induction is dependent on at least a minimal level of alkaline phosphatase activity, although it is not dependent on induction of alkaline phosphatase at the RNA level. If alkaline phosphatase is supplied exogenously, osteopontin expression can be induced in conditions in which endogenous alkaline phosphatase is severely repressed.

Studies on the hypomethylation of c-myc, c-Ha-ras oncogenes and histopathological changes in human gastric carcinoma.

In order to study the status of DNA methylation of specific oncogenes and the relationship between them and the pathological changes in gastric carcinoma, we analysed the methylated status of c-myc, c-Ha-ras oncogenes by Southern blot hybridization. Genomic DNA from cancerous, paracancerous and non-cancerous areas of surgically resected specimens were examined in 22 cases of advanced human gastric carcinoma. Specimens were digested by the restriction endonucleases MspI/HpaII, which are able to cleave between methylated and non-methylated cytosine at their nucleotide recognition site the DNA 5'-CCGG sequence, and were hybridized with c-myc, c-Ha-ras oncogene probes. Moreover, the corresponding pathological changes in gastric carcinoma were observed. The results showed that c-myc, c-Ha-ras oncogenes from cancerous (10/22, 5/10) and paracancerous areas (13/22, 4/10) were hypomethylated and that there was no significant relationship between them and the histopathological changes.

Expression of multiple oncogenes in human esophageal carcinomas.

To study the oncogenesis of human esophageal carcinoma, the expression of a variety of oncogenes was studied in 10 esophageal carcinoma cell lines and 16 pairs of tumor and nontumor tissues removed from patients with esophageal carcinoma. Northern blot analyses using 11 different oncogene probes revealed that 5 oncogenes, i.e. c-myc, c-H-ras, c-sis, c-raf, and c-fos, were expressed. Among them, a variant c-sis mRNA transcript of 2.7 kilobase (kb) was expressed in 7 of 10 cell lines and in 9 of 16 tumor tissues. Furthermore, an overexpression and an amplification of c-myc gene was observed in some cell lines. These results suggest that multiple oncogene expression may be required for the induction, maintenance, and progression of esophageal carcinoma. The expression of a 2.7-kb transcript, of c-sis and overexpression of c-myc gene may play some role in the carcinogenesis of esophageal carcinoma.

Amplification of a c-yes-1-related oncogene in canine lymphoid leukemia.

Genomic DNAs from 4 canine spontaneous lymphoid neoplasms were examined by Southern blot hybridization using 7 kinds of oncogene probes. Analysis using a human c-yes-1 cDNA probe revealed amplification of the proto-oncogene in a DNA sample from a dog with lymphoid leukemia. Its degree was about 4- to 8-fold in comparison with a control DNA sample from a healthy dog. The genomic abnormality of canine c-yes-1-related oncogene may have a role in the tumorigenesis of this neoplasm, although the significance of the structural change in this oncogene remains unclear.

Specific expression of cellular oncogenes c-myc and c-myb in T-cell lines established from three types of bovine lymphosarcomas

Summary Expression of cellular oncogenes in 3 lymphoid cell lines, BTL-PC3 (BoCD2−, BoCD4−, BoCD8−, BoWC1+), BLS1 (BoCD2+, BoCD4−, BoCD8−, B0WC1+) and BLT2 (BoCD2−, BoCD4−, BoCD8−, BoWC1−), which have been established from calf, skin, and thymic types of lymphosarcomas, respectively, were analyzed by dna-rna (northern blot) hybridization. To determine specific expression of oncogenes involved in malignant transformation of the lymphoid cells, cellular rna was isolated from bovine tumor cell lines, BTL-PC3, BLS1, and BLT2, and from Madin Darby bovine kidney cells used as a control for bovine cell lines. The rna was hybridized against 5 viral oncogene probes (v-jun, v-myc, v-erbB, v-erbA and v-fes), 6 human cellular oncogene probes (N-ras, c-Blym-1 c-erbB-2, c-fos, c-myb and c-abl), human p53 tumor suppressor gene, and bovine LDH-A gene probes. Line BTL-PC3 expressed 2.4-kilobase (kb) c-myc and 4.0- and 3.6-kb c-myb transcripts, and line BLT2 expressed a 3.8-kb c-myb transcript, but line BLS1 expressed no message for the oncogenes tested. Specific transcripts of p53 were found in BTL-PC3 and BLT2 lines, but not in BLS1. Madin Darby bovine kidney cell line expressed multiple cellular oncogenes, c-jun, c-myc, and c-fos, and p53 genes. Southern blot hybridization did not reveal abnormal dna rearrangements associated with the expressed oncogenes (c-myc and c-myb) in the 3 bovine tumor lines. From these results and the immunophenotype of the lymphoid cells, it appeared that c-myb specific mRNA were transcribed more often in immature bovine leukemia T cells (calf and thymic types) than in mature T cells from the skin type.

The application of fluorescent in situ hybridization to detect Mbcr/abl fusion in variant Ph chromosomes in CML and ALL

We investigated the usefulness of fluorescent in situ hybridization with different-colored major breakpoint cluster region (M bcr) and Abelson oncogene ( abl) probes in clinical practice. In standard Ph chromosomes with a M bcr breakpoint, these probes produced a fusion of M bcr and abl signals that was visible in interphase and metaphase cells. The normal range for apparent M bcr/abl fusion signals in interphase nuclei was established in bone marrow from 25 normal controls. We tested the probes on 35 bone marrow specimens from five normal subjects and 29 patients with various kinds of Ph chromosomes and chronic myelogenous leukemia or acute lymphocytic leukemia. This method produced M bcr/abl fusion signals in patients with a standard Ph chromosome, simple or complex variants of Ph chromosomes, and “Ph-negative chronic myelogenous leukemia.” In metaphase cells of patients with acute lymphocytic leukemia, this method established Ph chromosomes with minor bcr (m bcr) breakpoints. Fluorescent in situ hybridization is a relatively inexpensive and rapid method. When this method is used in conjunction with conventional chromosome analysis, the cytogeneticist can combine the power of complete karyotype studies and the resolution of molecular techniques for patients suspected of having a Ph chromosome.

Recurrent abnormalities of chromosome bands 10q23-25 in non-Hodgkin's lymphoma.

Many nonrandom chromosome abnormalities have been associated with non-Hodgkin's lymphomas (NHL). Some of these are nonspecific changes seen in many different histologic subtypes. We describe a series of abnormalities of chromosome bands 10q23-25 seen in 159 consecutive NHL patients with abnormal cytogenetic findings. The proportion of karyotypes with abnormalities of 10q varied from 3% among the immunoblastic lymphomas to 67% in the diffuse large cleaved cell lymphomas. Seventeen (10.7%) had abnormalities of 10q23-25. All but one of these were B-cell tumors. The abnormalities consisted of six deletions and 11 translocations. Sixteen of the 17 patients had the 10q abnormality when cells were first karyotyped. The remaining patient acquired the 10q abnormality in the third of a series of biopsies. In the follicular histologic subtypes [follicular small cleaved cell (FSC), follicular mixed small cleaved and large cell (FM), and follicular large cell noncleaved (FL-NC)], abnormalities of 10q were found in nine patients, all in association with abnormalities of 14q32. Seven of these were associated with the t(14;18)(q32;q21). Overall, 10q23-25 abnormalities were observed in 11.9% (8/67) of low-grade [small lymphocytic (SL), FSC, and FM] lymphoma cases. DNA was available from five patients with abnormalities of 10q and was probed for rearrangements with the HOXII (TCL3) oncogene probe. As expected, we did not find such rearrangements in these five patients with B-cell tumors. Abnormalities of 10q23-25 have been reported previously in NHL but not at this frequency.

Use of cellular oncogene probes to identify Morone hybrids.

We tested the ability of cellular oncogene (c-onc) probes to identify F1 hybrids and the lineage of known backcrosses within the fish genus Morone. Total DNA was isolated from five to 14 individuals per North American Morone species (striped bass, white bass, white perch, and yellow bass). The DNA was digested with two restriction enzymes, Eco RI and Hin dIII, Southern blotted, and hybridized to six different c-onc probes including v-abl, v-erb B, c-myc, c-H-ras, c-K-ras, and v-src. We found fixed genotypic differences among the four species for all six probes in single restriction enzyme digests. The heritability of these nuclear DNA genotypes was evaluated in hatchery-produced F1 Morone hybrids (striped bass x white bass and striped bass x white perch) tested with the six informative single probe/restriction enzyme combinations. All F1 individuals exhibited heterozygosity in all diagnostic nuclear DNA fragments, confirming the Mendelian inheritance of these genotypes in these fish. Furthermore, analysis of these nuclear DNA genotypes in hatchery-produced backcrosses of F1 hybrids striped bass x (white bass x striped bass) detected both recombinant and parental genotypes at all six polymorphic c-onc sequences. The lineage of suspected Morone hybrids of unknown descent collected from Lewis Smith Lake, Alabama, and from the Occoquan River, Virginia, was determined using the c-onc probes. Our results suggest that c-onc probes are suitable markers to unequivocally identify F1 hybrids and backcrosses and to quantify introgression in natural populations of fishes. The addition of RFLP analysis of mtDNA provided a complete ancestral history of individual fish.

Preferential expression of c-kit protooncogene transcripts in small cell lung cancer : Sekido Y, Obata Y, Ueda R, Hida T, Suyama M, Shimokata K et al. Laboratory of Immunology, Aichi Cancer Center, Chikusa-ku, Nagoya 464. Cancer Res 1991;51:2416–2419

As an initial step to understand rapid growth of small cell lung cancer (SCLC), a complementary DNA library prepared from a SCLC cell line was screened with viral oncogene probes encoding protein-tyrosine kinases, which are known to play an important role in regulation of cell growth. Fifteen clones hybridizing with v-fms probe were isolated, and, by partial sequence analysis, four of them were identified to be c-kit protooncogenes. Northern blot study demonstrated that most of the SCLC tumors and cell lines expressed c-kit transcripts, while non-SCLC tumors and cell lines did not. Neither amplification nor rearrangement of the c-kit gene was demonstrated in SCLC cell lines by Southern blot analysis, however. Our results suggested that c-kit expression in SCLC reflects the unique biological nature of the tumor cells different from non-SCLC and further suggested that the c-kit product may participate in autocrine or paracrine stimulation of SCLC growth.

Expression of gene-specific RNA in cultured cells exposed to rotating 60-Hz magnetic fields

Replicate sets of cultures of mouse and of human cells were exposed to cyclic, sine wave, 60-Hz rotating magnetic fields of 1.0 Gs (1 Gs [symbol: see text] 0.1 mT) for 24-, 48-, or 72-h periods. Total RNA extracted from unexposed control and from magnetic field exposed cells was dot blot hybridized to a number of oncogene probes (including v-myc, v-fos, v-raf, and v-Ha-ras), a probe for 3611 murine sarcoma virus, a probe for the 70,000 dalton heat shock protein (hsp70), and a probe for the long terminal repeat sequence of mouse mammary tumor virus. Comparisons of levels of RNA in unexposed and magnetic field exposed cells measured by densitometer readings of resulting autoradiographs revealed no significant increases or decreases in RNA levels in magnetic field exposed cells with the seven probes tested.

Repair of transcriptionally active and inactive genes during S and G2 phases of the cell cycle

To study the effect of ultraviolet irradiation on S and G2 phases of the cell cycle, BB88 mouse cells synchronized by a double thymidine block were exposed to ultraviolet light, and rates of DNA synthesis and mitotic indexes were determined at regular intervals. It was found that with increasing ultraviolet dose, semiconservative DNA synthesis decreased and the sharp mitotic wave observed in the unirradiated cells gradually degenerated. To study repair, semiconservative DNA replication was inhibited with hydroxyurea at different time intervals after releasing cells from the block and the DNA synthesized as a result of repair of the ultraviolet damage was labeled with 5'-bromodeoxyuridine (BrdU). The newly repaired DNA was separated from bulk DNA by immunoprecipitation with monoclonal anti-BrdU antibody, labeled with 32P and hybridized to nine different gene and oncogene probes dot-blotted in excess on nylon membranes to determine their abundance in the repaired DNA. The results showed that: (a) the most actively repaired segment was a 211-bp sequence adjacent to the promotor region of the beta-actin gene; (b) all transcriptionally active genes were repaired at similar and constant rates throughout S and G2 phases; (c) the nontranscribed genes were repaired at much lower rates in early S phase, but later in S phase and especially in G2 phase, their repair rates increased and approached those of the transcribed genes.

Cross-hybridization between the avian myeloblastosis oncogene and eukaryotic 28S ribosomal RNA

In Northern blots, avian myeloblastosis ( myb) oncogene probes (genomic or cDNA) cross-hybridize to the 28S rRNA band mimicking a myb-specific transcript. A misinterpretation of the hybridization data can be avoided by using an oligodeoxyribonucleotide probe.

Abnormal structure of the canine oncogene, related to the human c-yes-1 oncogene, in canine mammary tumor tissue

SUMMARY Cellular oncogenes of genomic dna in 6 canine primary mammary tumors were screened by Southern blot analysis, using 7 oncogene probes. A canine genomic oncogene related to the human c-yes-1 oncogene was detected as abnormal bands in solid carcinoma genomic dna digested with EcoRI, HindIII, HindIII-EcoRI, or HindIII-BamHI. Comparison was made between other tumor specimens and control specimens obtained from 4 clinically normal dogs—1 mixed breed and 3 Shiba Inu dogs (the same breed as the dog from which the solid carcinoma was obtained). These abnormal bands were 0.1 to 1 kilobase shorter than the normal gene. However, digestion of genomic dna obtained from normal wbc of this dog also produced all of the abnormal bands as observed in digested dna from the solid carcinoma tissue. Therefore, in this dog, the genomic dna of all somatic cells from the ontogenic stage still had the abnormal sequences related to the human c-yes-1 oncogene, and it is possible that this abnormal structure may have some role (eg, as an initiator) in tumorigenesis or the progression of this tumor.

Rearrangement of the chromosome 11 bcl-1 locus in centrocytic lymphoma: analysis with multiple breakpoint probes

Centrocytic lymphoma is a B-cell non-Hodgkin's lymphoma (NHL) composed of lymphocytes resembling cleaved follicular center cells (centrocytes). Previous studies have suggested an association between t(11;14) chromosomal translocations and bcl-1 rearrangement in centrocytic and related intermediate lymphocytic lymphomas. To further characterize the association between bcl-1 and centrocytic lymphoma, Southern blot analysis was performed on samples from 23 patients using four separate bcl-1 breakpoint probes spanning 63 kb of the chromosome 11 bcl-1 locus. Rearrangements were identified in six patients with the major translocation cluster (MTC) probe and in another six with probe p94PS, located about 24 kb 5′ of MTC. Eleven of these 12 cases showed comigration of rearranged bcl-1 and Ig heavy chain-joining genes, consistent with the t(11;14) chromosomal translocation. No rearrangements were observed with the bcl-1 locus probes p210 or p11EH located 5′ of p94PS, nor with bcl-2 or c-myc oncogene probes. No bcl-1 rearrangements were identified in B-cell follicular NHL (15), small noncleaved cell (Burkitt's and non-Burkitt's) NHL (8), T-cell NHL (4), multiple myeloma (14), and pre-B-cell acute lymphoblastic leukemia (9). One of 23 B-cell NHL of large cell type and one of 19 chronic lymphocytic leukemias or small lymphocytic NHL had MTC rearrangement. Thus, bcl-1 rearrangement occurred at MTC or p94PS in 12 of 23 centrocytic lymphomas (52%), confirming a nonrandom association and suggesting a pathogenetic role for the bcl-1 locus in this immunohistologic subtype of NHL.

Rearrangement of the Chromosome 11 bcl-1 Locus in Centrocytic Lymphoma: Analysis With Multiple Breakpoint Probes

Centrocytic lymphoma is a B-cell non-Hodgkin's lymphoma (NHL) composed of lymphocytes resembling cleaved follicular center cells (centrocytes). Previous studies have suggested an association between t(11;14) chromosomal translocations and bcl-1 rearrangement in centrocytic and related intermediate lymphocytic lymphomas. To further characterize the association between bcl-1 and centrocytic lymphoma, Southern blot analysis was performed on samples from 23 patients using four separate bcl-1 breakpoint probes spanning 63 kb of the chromosome 11 bcl-1 locus. Rearrangements were identified in six patients with the major translocation cluster (MTC) probe and in another six with probe p94PS, located about 24 kb 5' of MTC. Eleven of these 12 cases showed comigration of rearranged bcl-1 and Ig heavy chain-joining genes, consistent with the t(11;14) chromosomal translocation. No rearrangements were observed with the bcl-1 locus probes p210 or p11EH located 5' of p94PS, nor with bcl-2 or c-myc oncogene probes. No bcl-1 rearrangements were identified in B-cell follicular NHL (15), small noncleaved cell (Burkitt's and non-Burkitt's) NHL (8), T-cell NHL (4), multiple myeloma (14), and pre-B-cell acute lymphoblastic leukemia (9). One of 23 B-cell NHL of large cell type and one of 19 chronic lymphocytic leukemias or small lymphocytic NHL had MTC rearrangement. Thus, bcl-1 rearrangement occurred at MTC or p94PS in 12 of 23 centrocytic lymphomas (52%), confirming a nonrandom association and suggesting a pathogenetic role for the bcl-1 locus in this immunohistologic subtype of NHL.