Establishment of a near-triploid human B-cell lymphoma cell line with t(14;18) and a p53 gene point mutation

Hypermethylation of the putative tumor-suppressor genes DCC, p51/63 and O6-methylguanine-DNA methyltransferase (MGMT) and loss of their expressions in cell lines of hematological malignancies

Alterations and defective expression of three putative tumor-suppressor genes, the deleted in colorectal cancer (DCC), p51, and O(6)-methylguanine-DNA methyltransferase (MGMT), have been demonstrated in many cancers. However, it is not known whether the defective expression of each of these genes is independent or whether it reflects a specific methylation abnormality. Here, we investigated the expression of the DCC, p51 and MGMT genes and the methylation status of the 5' flanking CpG region in 17 cell lines established from hematological malignancies. The reverse transcriptase-polymerase chain reaction method showed DCC expression to be absent in 13 of the 17 cell lines and showed expression of both p51 and MGMT to be absent in 5 of the 17 cell lines. The methylation patterns were analyzed with methylation-specific polymerase chain reaction (MSP) of the 5'flanking region of the DCC and p51 genes and the promoter region of the MGMT gene. Although unmethylated patterns of the CpG region in the DCC, p51, and MGMT genes were observed in all 11 normal controls, abnormal methylation patterns of these genes were found even in many cell lines expressing these genes. A hypermethylation pattern was detected for the CpG region of MGMT and p51 in cells that did not express these genes. In contrast, a hypermethylation pattern was not always detected for the CpG region of DCC in cells with reduced DCC expression. The results of this study indicate that in many hematological cell lines, the DCC, p51, and MGMT genes have been abnormally methylated in the CpG region. Hypermethylation of these three genes may be independent events in each cell line.

Philadelphia chromosome-positive acute myeloid leukemia with tetraploidy

The patient was a 62-year-old man. His hematological data in April 2000 had shown no abnormalities, but he was referred to our hospital because of a fever and leukocytosis in June 2000. The peripheral blood showed 29.8 x 10(9)/L white blood cells, with 68.0% blasts. A bone marrow aspirate showed hypercellularity with a proliferation of large leukemic blasts. The leukemic cells were positive for CD13 (91%), CD33 (54.8%), CD34 (94.5%), and HLA-DR (97.9%). Some leukemic cells (15.6%) also expressed CD14. Cytogenetic analysis revealed 92,XXYY,t(9;22)(q34;q11)x2 in all 20 metaphase cells. Reverse transcriptase polymerase chain reaction analysis detected the minor BCR/ABL messenger RNA (mRNA) but failed to detect the major BCR/ABL mRNA. The patient achieved complete remission after induction chemotherapy, with no evidence of Philadelphia chromosome (Ph) or minor BCR/ABL mRNA. Ph-positive acute myeloid leukemia (Ph-AML) has rarely been reported. Herein, we report a case of Ph-AML with tetraploidy and review the previously reported Ph-AML cases.

Low frequency of BCL-2/J(H) translocation in peripheral blood lymphocytes of healthy Japanese individuals

The incidence of follicular lymphoma differs significantly between white and Japanese individuals. Translocation between the BCL-2 and immunoglobulin heavy chain genes is detected in 85% to 90% of all follicular lymphomas in whites. Recently, BCL-2/J(H) translocation was detected in peripheral blood lymphocytes from more than 50% of healthy white individuals. To clarify the reason for the difference in incidence of follicular lymphoma between whites and Japanese, the frequency of BCL-2/J(H) translocation in peripheral blood lymphocytes of healthy Japanese individuals was compared with that of German individuals. The prevalence of BCL-2/J(H) translocation in Japanese adults appeared to be significantly lower than that in German adults. The present data suggest that the low frequency of BCL-2/J(H) translocation in the Japanese general population may be one of the major reasons for the difference in incidence of follicular lymphoma between whites and Japanese.

Disturbed expression of the anti-apoptosis gene, survivin, and EPR-1 in hematological malignancies

Survivin is a newly discovered inhibitor of the apoptosis protein, IAP, expressed during development and in human cancers. The effector cell protease receptor-1 (EPR-1) gene is oriented in the opposite direction on the same DNA double strand. Thus, the Survivin and EPR-1 (Survivin/EPR-1) genes exist in a head-to-head configuration. It is not clear whether mutual expression of the Survivin/EPR-1 genes occurs in both normal cells and cancer cells. Here, we investigated the mutual expression of the Survivin/EPR-1 genes in 12 normal peripheral blood (PB) specimens, seven normal bone marrow (BM) specimens, five lymph node (LN) specimens, and seven leukemic cell lines, and 27 patients with malignant lymphoma (ML), four with acute lymphocytic leukemia (ALL), three with acute myelocytic leukemia (AML), and four with chronic myelocytic leukemia in blastic crisis (CML-BC). Using Northern blot analysis, small amounts of EPR-1 mRNA were detected in normal PB, normal BM and LN specimens, but no Survivin mRNA was detected. However, Survivin mRNA was detected in two of the 12 normal PB, six of the seven normal BM and one of the five LN specimens using reverse transcription and polymerase chain reaction (RT-PCR). Expression of both the Survivin and EPR-1 genes was detected in six of the seven cell line samples by Northern blot, and in all of them by RT-PCR. Mutual expression of the Survivin and EPR-1 genes was detected in three of the four CML-BC samples, 15 of the 27 ML samples, two of the four ALL samples, and all three AML samples using the RT-PCR method. No EPR-1 expression with or without Survivin expression was clearly detected in eight of the nine diffuse large B-cell lymphoma (DLB) specimens, two of the six follicular center lymphoma specimens, one of the four specimens of nodular sclerosis of Hodgkin's lymphoma, two of the four ALL specimens or one of the four CML-BC specimens. The data presented here show that disrupted expression of the Survivin/EPR-1 genes occurred in many kinds of hematologically malignant cells. This may be of biological importance.