Gene targeting studies in mice have shown that the lack of Ikaros activity leads to T-cell hyperproliferation and T-cell neoplasia, establishing the Ikaros gene as a tumor suppressor gene in mice. This prompted us to investigate whether mutations in Ikaros play a role in human hematological malignancies. Reverse transcription-PCR was used to determine the relative expression levels of Ikaros isoforms in a panel of human leukemia/lymphoma cell lines and human bone marrow samples from patients with hematological malignancies. Among the cell lines examined, only BV-173, which was derived from a chronic myelogenous leukemia (CML) patient in lymphoid blast crisis, overexpressed the dominant-negative isoform, Ik-6. In 9 of 17 samples of patients in blast crisis of CML, Ikaros activity had been reduced either by drastically reducing mRNA expression (4 of 17) or by overexpressing the dominant-negative isoform Ik-6 (5 of 17). Significantly, expression of Ikaros isoforms seemed normal in chronic phase CML patients and patients with other hematological malignancies. In some cases, overexpression of the dominant-negative Ik-6 protein was confirmed by Western blot analysis, and Southern blot analysis indicated that decreases in Ikaros activity correlated with a mutation in the Ikaros locus. In summary, these findings suggest that a reduction of Ikaros activity may be an important step in the development of blast crisis in CML and provide further evidence that mutations that alter Ikaros expression may contribute to human hematological malignancies.

We established two novel PH-positive acute leukemia cell lines with "biphenotypic" feature, NALM-27 and NALM-28, with t(9;22;10)(q34;q11;q22) from a patient with biphenotypic acute leukemia(BAL). The breakpoint cluster region (bcr) of the BCR gene was found to be rearranged in these cells by Southern blot analysis using a major 3'-side bcr probe. Polymerase chain reaction (PCR) results showed differences in the pattern of expression of the abl-bcr fusion gene in comparison with the diagnosis. In the case of variant Ph translocations, reports have appeared concerning mainly chronic myelogenous leukemia (CML), but there have been few concerning acute leukemia with lymphoid feature. This study thus identifies nonrandomly involved chromosome sites which can then be targeted for detailed molecular analysis to obtain an understanding of abl-bcr fusion in the cells with lymphoid feature. In addition, chromosome band 10q22, involved in this translocation, is the site for several neoplasia. Furthermore, this site is non-randomly involved in the formation of variant Ph translocations in acute lymphoblastic leukemia (ALL). This is the first report on the t(9;22;10)(q34;q11;q22) rearrangement in NALM-27 and NALM-28 cell lines which should prove useful for understanding the translocation of molecular breaks within the bcr of the complex translocation site.

The human Evi-1 gene located on chromosome 3q26, encodes a zinc finger protein that functions as a transcription factor. It was frequently overexpressed in leukemias having 3q26 abnormalities such as t(3;3)(q21;q26) and inv(3)(q21 q26), and subjected to structural alteration in t(3;21)(q26;q22). In addition, recent studies indicated that several cases of leukemias without 3q26 abnormalities also expressed Evi-1 gene. In this study we present another case of structural alteration of Evi-1 gene in a case of inv(3)(q21 q26), in which Evi-1 was truncated and a shorter form of Evi-1 protein was expressed upon rearrangement of the gene. We also studied expression of the Evi-1 gene in a variety of leukemias by northern blot analysis. Evi-1 was overexpressed not only in leukemias with 3q26 abnormalities, but, in those without 3q26 abnormalities, especially in blast crisis of CML. Our result also supports an idea that Evi-1 is a relevant oncogene whose overexpression or structural changes might play a crucial role in development of human leukemias.

A human acute lymphoblastic leukemia (ALL) cell line, BALM-9, was established from the peripheral blood specimen of a immunoglobin (lg) phenotype, the established BALM-9 cell line expressed both kappa and lambda light (L) chains simultaneously in a range of 30-80%. Two-color flow cytometric analysis demonstrated that there was a distinct population of kappa lambda double positive cells as well as kappa single, lambda single, and double negative populations. Therefore, subclones were obtained from each population by limiting dilution and were designated BALM-9KL (kappa+lambda+), BALM-9K (kappa+lambda-), BALM 9N (kappa-lambda-). Western blotting confirmed the results of the immunofluorescence test at the protein level. In BALM-9N, L chains were absent even in the cytoplasm as demonstrated by Western blotting. Evidence that the subclones have the same ancestry was provided both by cytogenetic analysis and by Southern blotting, which revealed the 14q32 chromosomal rearrangement as a common abnormality and the same IgH gene arrangement among the subclones. The existence of a kappa lambda positive B cell population suggests a transient stage of normal B cell maturation. These subclones might represent such a stage and thus provide a useful means of analyzing the mechanism of this double light chain expression.

Overexpression of the Evi-1 gene appears to be a consistent feature of the 3q21q26 syndrome, an association of myeloid leukemias/myelodysplastic syndrome with a specific chromosomal aberration involving both 3q21 and 3q26, such as t(3;3)(q21;q26) or inv(3)(q21q26). The rearrangement in 3q26 has been reported to occur near the Evi-1 locus, implicating that it is the critical gene deregulated in the 3q21q26 syndrome. Here we present a structural abnormality of Evi-1 protein in a case with the 3q21q26 syndrome. In this case carrying typical inv(3)(q21q26), the 3q26 breakpoint is located within an intron of the Evi-1 gene, and resulted in overexpression of normally unexpressed, an aberrant form of Evi-1 protein, in which the C-terminal 44 amino acids of wild-type Evi-1 protein were truncated and replaced by five amino acids. The truncated Evi-1 protein is shown to increase AP1 activity when expressed in NIH3T3 cells as its wild-type counterpart. We also show that the origin of this peculiar type of rearrangement of the Evi-1 gene is not an artifact during establishment of the cell line, but is the event that occurred in the primary leukemic cells. Our results strongly support that the primary target for the 3q21q26 syndrome is the Evi-1 gene, and provide the first evidence that the structurally altered Evi-1 gene may be involved in the 3q21q26 syndrome.

Seven cell lines, MOLM-6, -7, -8, -9, -10, -11 and -12, were established from a single blood sample from a patient with chronic myelogenous leukemia (CML) in blastic phase having the Ph1 chromosome abnormality. Based on immunophenotyping, two of these seven cell lines, MOLM-7 and -11, represented the megakaryoblastoid lineage, and the other five cell lines represented two different maturation stages of the myeloid lineage.

A new pre-B cell leukemia cell line, NALM-26, was established from the peripheral blood of a 24-year-old male patient with acute pre-B cell leukemia. NALM-26 is unique in its expression of T cell-associated CD5 and myeloid cell-associated CD13 antigens. Interleukin-7 (IL-7) receptor (CDw127) was detected by flow cytometric analysis. After PMA treatment, NALM-26 was induced to express CD20, CD25 and CD28, and to increase its expression of both CD5 and CD13. The expression of CDw127 was down-modulated.

Multiple myeloma cell lines, MOLP-2 and MOLP-3, were established from the peripheral blood of a patient in leukemic phase of multiple myeloma. Both cell lines express the IL-6 receptor, CD28 T cell-associated antigen and CD33 myeloid-associated antigen. IgD lambda immunoglobulin was found in the culture supernatants of both MOLP-2 and MOLP-3.

Three leukemia cell lines, BALM-6, -7 and -8 were established from the bone marrow of a patient with acute lymphoblastic leukemia. Based on immunophenotypic and the cytogenetic analysis and on the expression of immunoglobulins on both the cell surface and in the cytoplasm, BALM-6, BALM-7 and BALM-8 are clonal leukemic cell populations of B cell origin.

Based on the immunophenotypic, cytogenetic and genotypic findings, two unique leukemia cell lines, NALM-24 and NALM-25, and an EBV-transformed "normal" B-lymphoblastoid cell line (B262) from a patient with ALL were established and characterized. NALM-24 and NALM-25 are unique in that expression of both show B cell and myeloid cell features with the t(9;22) chromosome in single clonal leukemic cell populations.

Based on the morphological resemblance to megakaryocytes and upon the expression f the platelet specific glycoprotein antigen, CD61, it is highly l y that MOLM-1 is a clonal leukemic cell population of megakaryoblastic origin .

Based on the immunophenotypic and genotypic findings, this acute leukemia cell line, designated NALM-19, is unique in that a partial expression of both B-cell and myeloid cell features are present in this single clonal leukemic cell population. It is noteworthy that two "normal" EB virus-transformed B cell lines, B239 and B240, (paired with NALM-19) were established from the same leukemic blood.