AF17q25, a putative septin family gene, fuses the MLL gene in acute myeloid leukemia with t(11;17)(q23;q25).

The t(11;17) has been described in patients with acute myeloid leukemia (AML), and the AF17 gene was previously cloned as a fusion partner of the MLL gene in t(11;17)(q23;q21)-AML. We analyzed one patient with de novo AML and one with therapy-related AML with t(11;17)(q23;q25) and identified the AF17q25 gene on chromosome 17q25, a putative septin family gene, fused with MLL. AF17q25 encoded at least three kinds of proteins [type I (568 a.a.), type II (594 a.a.), and type III (574 a.a.)] that contained two kinds of different amino acid sequences at the COOH terminus. The MLL-AF17q25 fusion transcript consisted of type I AF17q25 transcript. The AF17q25 protein is homologous to septin family proteins, including H5, NEDD5, CDC10, and hCDCrel, which is one of the fusion partners of MLL in t(11;22)(q23;q11)-AML. These results suggest that AF17q25 and hCDCrel might define a new septin family particularly involved in the pathogenesis of 11q23-associated leukemia.

Expression and mutational analysis of the DCC, DPC4, and MADR2/JV18-1 genes in neuroblastoma.

Loss of heterozygosity (LOH) on chromosome 18q21 is found frequently in various human cancers. Three candidate tumor suppressor genes, DCC (deleted in colorectal carcinomas), DPC4 (deleted in pancreatic carcinomas, locus 4), and MADR2/JV18-1 (MAD-related gene 2), have been cloned and identified from this chromosome region. We have reported recently that LOH on chromosome 18q is observed frequently in neuroblastoma. Alterations of DCC are involved in many human tumors. DPC4 and MADR2/JV18-1 are recently demonstrated to be altered in pancreatic and colorectal cancers, respectively. To confirm if inactivation of the DCC, DPC4, and MADR2/JV18-1 genes is involved in the pathogenesis of neuroblastoma and to clarify the mechanism of inactivation, we analyzed the expression of DCC, DPC4, and MADR2/JV18-1 in neuroblastoma cell lines and primary tumors by reverse transcription-PCR and investigated the mutations in the coding regions of these genes by PCR/reverse transcription-PCR single-strand conformation polymorphism. We found that 12 of 25 (48%) cell lines and 14 of 32 (44%) primary tumors, including 3 with 18q LOH, had absent or reduced expression of DCC mRNA. Expression was more likely to be reduced in advanced (67%) than in early stage neuroblastomas (24%) (P = 0.036), suggesting that inactivation of the DCC gene plays an important role in the progression of neuroblastoma. Altered expression of DPC4 was found in six (24%) cell lines and six (19%) tumors. MADR2/JV18-1 expression was reduced or absent only in four (16%) cell lines and three (9%) tumors. Mutations of the DCC genes were examined in 25 of 29 exons in neuroblastoma cell lines, and those exons in which mutations were found were further examined in primary tumors. We found missense mutations of AAC (Asn) to AGC (Ser) at DCC codon 176 in one cell line and ACC (Thr) to ATC (Ile) at codon 1105 in one cell line and tumor, respectively; polymorphisms of CGA (Arg) to GGA (Gly) at codon 201 and TTT (Phe) to TTG (Leu) at codon 951 in most of the cell lines and tumors; and a silent mutation of GAG (Glu) to GAA (Glu) at codon 118 in four cell lines and five primary tumors. We did not identify any mutations in the DPC4 and MADR2/JV18-1 genes in neuroblastoma. Our results suggested that mutations of the DCC gene may be involved in the pathogenesis of neuroblastomas but failed to account for the relatively high frequency of the altered expression, implying that other mechanisms are responsible for the inactivation of the DCC gene in neuroblastoma. Low frequency of reduced or absent mRNA expression and lack of mutations in DPC4 and MADR2/JV18-1 genes suggested a limited role for these two genes in neuroblastoma.

SN-1, a novel leukemic cell line with t(11;16)(q23;p13): myeloid characteristics and resistance to retinoids and vitamin D3.

The MLL gene is fused with the cAMP-responsive element binding protein-binding protein (CBP) gene in t(11;16)(q23;p13), which has been reported to be associated with therapy-related acute leukemia. We established a novel myeloid cell line, SN-1, from a patient with T-cell acute lymphoblastic leukemia with t(11;16)(q23;p13) having in-frame MLL-CBP fusion transcripts. The majority of the SN-1 cells were positive for myeloperoxidase when examined using an electron microscope and expressed CD13, CD33, CD56, and HLA-DR antigens, but not CD7, CD10, CD19, CD34, or CD41 antigens, suggesting that these cells are of myeloid origin. SN-1 cells underwent functional and morphological differentiation when treated with actinomycin D or sodium butyrate, but not with all-trans-retinoic acid (ATRA) or 1alpha,25-dihydroxyvitamin D3 (VD3). Exposure of SN-1 cells to ATRA hardly affected cell growth and differentiation, whereas the growth of HL-60 and NB4 cells treated with ATRA was effectively inhibited, and differentiation into mature granulocytes was induced. SN-1 cells were relatively insensitive to VD3 with respect to inhibiting the cell growth and inducing the ability to reduce nitroblue tetrazolium, lysozyme activity, and morphological differentiation, although the expression of CD11b was slightly induced by VD3. These results suggest that the cell line was impaired in the signal transduction systems of ATRA and VD3. This cell line should be useful for the study of the role of CBP as a transcriptional regulator in leukemia differentiation and for the functional analysis of the MLL-CBP fusion gene, which will provide new insights into leukemogenesis caused by 11q23 translocations.

Six months of maintenance chemotherapy after intensified treatment for acute lymphoblastic leukemia of childhood.

PURPOSE: We postulated that intensification of chemotherapy immediately after remission induction might reduce the leukemic cell burden sufficiently to allow an abbreviated period of antimetabolite therapy. PATIENTS AND METHODS: Three hundred forty-seven children (ages 1 to 15 years) with previously untreated acute lymphoblastic leukemia (ALL) were enrolled onto the Tokyo L92-13 study, which excluded patients with mature B-cell ALL and patients less than 1 year old. One hundred twenty-four patients were classified as standard risk, 122 as high risk, and 101 as extremely high risk, according to age, peripheral-blood leukocyte count, selected genetic abnormalities, and immunophenotype. All subjects received four drugs for remission induction, followed by a risk-directed multidrug intensification phase and therapy for presymptomatic leukemia in the CNS. Maintenance chemotherapy with oral mercaptopurine and methotrexate was administered for 6 months, with all treatment stopped by 1 year after diagnosis. RESULTS: The mean (+/- SD) event-free survival (EFS) and overall survival rates for all patients were 59.5% +/- 3.4% and 81.5% +/- 2.2%, respectively, at 5. 5 years after diagnosis. EFS rates by risk category were similar (60. 2% +/- 6.0% for standard risk, 57.7% +/- 5.6% for high risk, and 62. 5% +/- 5.7% for extremely high risk), whereas overall survival rates differed significantly (91.2% +/- 2.7%, 80.0% +/- 4.1%, and 72.1% +/- 4.5%, respectively, P <.0001 by the log-rank test). There were 107 relapses. Eighty-five (79.4%) of these 107 patients achieved second complete remissions, with subsequent EFS rates of 61.5% +/- 7. 9% (standard risk), 42.6% +/- 8.1% (high risk), and 9.6% +/- 6.4% (extremely high risk). Of the five risk factors analyzed, only the response to prednisolone monotherapy among extremely high-risk patients proved important. CONCLUSION: Early treatment intensification did not compensate for a truncated phase of maintenance chemotherapy in children with standard- or high-risk ALL. However, 6 months of antimetabolite treatment seemed adequate for extremely high-risk patients who were good responders to prednisolone and received intensified chemotherapy that included high-dose cytarabine early in the clinical course.

Long-term survivors of advanced neuroblastoma with MYCN amplification: A report of 19 patients surviving disease-free for more than 66 months.

PURPOSE: According to initial reports, stage 4 neuroblastoma patients with amplification of the MYCN proto-oncogene developed progressive disease within 8 months. The prognosis for such patients, however, should now be reevaluated in light of recent results achieved with up-to-date combination chemotherapy. PATIENTS AND METHODS: Patients with stage 3, 4, and 4S neuroblastoma and more than 10 copies of MYCN received induction chemotherapy, which from January 1985 to February 1991 consisted of regimen A(1 )(cyclophosphamide 1,200 mg/m(2) on day 1, vincristine 1.5 mg/m(2) on day 1, pirarubicin 40 mg/m(2) on day 3, and cisplatin 90 mg/m(2) on day 5) and from March 1991 to September 1993 consisted of regimen A(3 )(cyclophosphamide 1,200 mg/m(2) on days 1 and 2, pirarubicin 40 mg/m(2) on day 3, etoposide 100 mg/m(2) on days 1 through 5, and continuous infusion cisplatin 25 mg/m(2) on days 1 through 5). Most of these patients underwent radical surgery to remove the original tumor and local metastases, irradiation, and supralethal preconditioning regimens, followed by blood stem-cell transplantation (SCT). Data on the patients were collected in December 1998, and the factors contributing to disease-free survival were analyzed. RESULTS: During the study period, 66 patients with more than 10 copies of MYCN were treated. Five of nine patients with stage 3 disease, 13 of 55 with stage 4, and one of two with stage 4S survived for at least 66 months. It is interesting that all but one patient who survived for more than 66 months underwent SCT, in contrast with only five of 45 patients who died. CONCLUSION: Not all patients with advanced neuroblastoma who have more than 10 copies of MYCN will die. The requisites for survival in such patients seem to be intensive induction chemotherapy, effective surgery, irradiation, and the use of SCT.

Delay of the diagnostic lumbar puncture and intrathecal chemotherapy in children with acute lymphoblastic leukemia who undergo routine corticosteroid testing: Tokyo Children's Cancer Study Group study L89-12.

PURPOSE: To determine the effects of eliminating initial lumbar punctures in 418 consecutively treated children with acute lymphoblastic leukemia (ALL). PATIENTS AND METHODS: Patients were enrolled onto a trial conducted in central Japan between 1989 and 1992. Treatment consisted of standard four-drug induction therapy followed by a risk-based intensification phase, reinduction therapy, late intensification, and remission maintenance therapy (total of 104 weeks). The initial lumbar puncture, with an intrathecal injection of chemotherapy, was performed after 1 week of prednisolone sensitivity testing (day 8). End points included response to prednisolone, CNS status at the time of the day 8 lumbar puncture, subsequent adverse events in CNS and bone marrow, and event-free survival (EFS). RESULTS: The remission induction rate was 93.1% with a 6-year EFS rate (+/- SE) of 68.7% +/- 2.4%, which is similar to historical results for patients who received their diagnostic lumbar puncture and first instillation of intrathecal chemotherapy on day 0. Overall, 84.5% of the patients had good responses to prednisolone, whereas 15.5% had poor responses. Clinical outcome was strikingly better for the good responders (6-year EFS, 74.1% +/- 2.5% compared with 40.1% +/- 6.4% for patients with poor responses), suggesting that omission of intrathecal chemotherapy did not alter the predictive value of drug sensitivity testing. Eighteen patients experienced CNS relapse as their first adverse event (cumulative risk, 5.1%; 95% confidence interval, 2.7% to 7.4%), coincident with reports from groups using conventional strategies of CNS clinical management. Bleeding into the CSF at the time of the day 8 lumbar puncture was apparent in 29 cases (8.1%), but leukemic blasts were identified in only two. CONCLUSION: Delay of the initial lumbar puncture and intrathecal injection of chemotherapy seems to be feasible in children with ALL. Further controlled evaluations are needed to establish the validity of this conclusion.

Clonal analysis of transient myeloproliferative disorder in Down's syndrome.

Three Down's syndrome patients with transient myeloproliferative disorder were studied for clonality of the proliferating blast cells using the X chromosome-linked polymorphic gene phosphoglycerate kinase, immunoglobulin heavy chain (IgH) gene and T-cell antigen receptor (TCR) (beta, gamma, delta) genes. None of the three cases showed rearrangements of IgH, TCR beta, gamma, or delta genes, indicating the non-lymphoid nature of the proliferating blast cells. The X chromosome inactivation pattern showed that the cells in the blast population in all of the three cases of transient myeloproliferative disorder were clonal. These data suggest that at least some of this disorder can be due to a spontaneously regressing clone of malignant cells.

Homozygous deletions of p16/MTS1 and p15/MTS2 genes are frequent in t(1;19)-negative but not in t(1;19)-positive B precursor acute lymphoblastic leukemia in childhood.

We analyzed 60 B precursor acute lymphoblastic leukemia (ALL) primary samples and 15 cell lines for homozygous deletions of p16 and p15 genes and mutations of p16 gene. These included five cell lines and 13 primary samples with the t(1;19)(q23;pl3), and eight primary samples with the t(9;22)(q34;qll). Of 10 cell lines without t(1;19), homozygous deletion of both p16 and p15 genes was found in eight cell lines (80%), and a rearrangement of p16 in one cell line (10%). In contrast, only one (20%) of the five cell lines with t(1;19) showed homozygous deletion or rearrangement of p16/p15 gene. Thirteen of 60 (22%) primary samples demonstrated p16 gene homozygous deletion. No case with t(1;19) showed homozygous deletion of p16 gene (0/13, 0%), while cases without t(1;19) showed considerable incidence of p16 gene homozygous deletion (13/47, 28%). These results suggest that the incidence of deletions of p16 gene differs according to the subtypes of B precursor ALL. We also compared the frequency of p16 gene homozygous deletion between the patients at diagnosis and at relapse. Nine of 45 (20%) samples at diagnosis and four of 22 (18%) samples at relapse showed p16 homozygous deletions. The similarity of the rate in these two groups raises the question of the role of p16 gene in progression of B precursor ALL. Mutations were found in three of the primary cases (5%); the mutations included two nonsense mutations at codon 72 and one missense mutation at codon 98. All the mutations found in this study were heterozygous, and the clinical relevance of p16 gene mutation is yet to be determined in these case

Frequency and clinical significance of the MLL gene rearrangements in infant acute leukemia.

We have analyzed the frequency and clinical significance of the MLL gene rearrangements in 42 cases of infant acute leukemias; including 37 cases of acute lymphoblastic leukemia (ALL) and five cases of acute myeloid leukemia (AML). MLL gene rearrangements were found in 27 of the 37 ALL cases (73 percent), and in all five AML cases. Cytogenetic studies showed 11q23 abnormalities in 24 of 27 ALL cases with MLL gene rearrangements. MLL gene rearrangements were significantly correlated with absence of CD10 expression and poor prognosis, but not with age under 6 months, hyperleukocytosis, myeloid-associated antigen expression, or CNS leukemia. The 3-year overall survival rate for ALL cases with MLL gene rearrangements was 5.3 +/- 5.2 percent, compared with 88.9 +/- 10.5 percent for cases with germline MLL (P=0.0001). Absence of CD10 expression was also associated with poor prognosis (9.9 +/- 6.6 percent vs 85.7 +/- 13.2 percent, P = 0.0003). Of the five AML cases, three have remained alive for 27 months to 67 months. These findings suggest that infant ALL with MLL gene rearrangement is strongly associated with poor prognosis. We consider that infant ALL should be treated on different chemotherapy protocols according to the presence or absence of MLL gene rearrangement.

Alterations of p16 and p15 genes in acute leukemia with MLL gene rearrangements and their correlation with clinical features.

p16 and p15 genes are putative tumor suppressor genes located on chromosome 9p21. In acute leukemias, alterations of p16 and p15 genes have been reported to occur exclusively in lymphoid lineage. We analyzed alterations of p16 and p15 genes in 46 acute leukemias with MLL gene rearrangements by Southern blot analysis, and investigated the association with clinical characteristics. We identified homozygous deletion of p16 and p15 genes in five (19%) of 27 acute lymphoblastic leukemias (ALLs) and in two (11%) of 19 acute myeloid leukemias (AMLs). Patients with homozygous deletion of p16 and p15 genes showed higher average leukocyte counts (343 x 10(9)/l vs 271 x 10(9)/l) and lower estimated 2-year survival rates than those with normal p16 and p15 genes (14.3 vs 30.7%), although the differences were not statistically significant. In addition, we investigated mutation of p16 gene by polymerase chain reaction single strand conformation polymorphism (PCR-SSCP) in 31 patients, but no mutation was found in the patients tested. Our results suggest that alterations of p16 and p15 genes are involved in a subset of acute leukemias with MLL gene rearrangement not only of lymphoid but also of myeloid phenotype. Homozygous deletion of p16 and p15 genes may be a possible adverse prognostic factor, although further analysis would be needed to confirm it.

Long-term follow-up of childhood acute lymphoblastic leukemia in Tokyo Children's Cancer Study Group 1981-1995.

The objectives were as follows: Firstly, to estimate the overall probability of event-free survival (EFS) and isolated CNS relapse in the studies for children with acute lymphoblastic leukemia (ALL) during the 1980s and 1990s. Secondly, to report the EFS according to presenting features and lineage. Thirdly, to evaluate the treatment results re-classified by the risks of NCI criteria. Four consecutive protocol studies were performed in the Tokyo Children's Cancer Study Group: L81-10 protocol (1981-1984, 189 patients), L84-11 (1984-1989, 484 patents), L89-12 (1989-1992, 418 patients) and L92-13 (1992-1995, 347 patients). Overall EFS at 5 years in each protocol was 56.5 +/- 3.8(1 s.e.)%, 71.0 +/- 2.1%, 67.8 +/- 2.3%, and 63.4 +/- 2.7%, respectively. The cumulative isolated CNS relapse rate at 5 years was 8.1 +/- 2.1%, 3.5 +/- 0.9%, 3.6 +/- 1.0%, 1.0 +/- 0.6. The EFS in SR/HR (standard risk/high risk) according to the NCI criteria in B-precursor ALL at 5 years was 61.9 +/- 4.3%/41.4 +/- 7.4% (lineage was not confirmed.), 72.5 +/- 2.6%/63.4 +/- 5.0%, 77.4 +/- 2.7%/56.3 +/- 4.7%, and 67.8 +/- 3.4%/56.7 +/- 5.4% in each protocol. Also EFSs according to NCI SR/HR at 5 years of T-ALL in protocols L84-11, L89-12 and L92-13 were 55.6 +/- 16.6%/60.9 +/- 10.1%, 72.7 +/- 13.4%/51.6 +/- 9.1%, and 77.1 +/- 14.4%/53.6/10.1%, respectively. The truncation of maintenance therapy to 6 months resulted in a decreased EFS in L92-13, particularly due to an increase of bone marrow relapse after cessation of therapy in SR and HR. The NCI risk criteria work properly even in the patients treated by different intensities, so that it makes the comparison possible among the patients in various groups. The overall EFSs in childhood ALL improved in 1980s, but it seemed stable or decreased in 1990s. The short maintenance therapy resulted in poor outcome in SR on the L92-13 protocol. Many of these late relapsers were effectively rescued and overall survival remained at a high level. The proportion of patients who received cranial irradiation reduced without any increase of the CNS events.

Codon 201(Gly) polymorphic type of the DCC gene is related to disseminated neuroblastoma.

The deleted in colorectal carcinoma (DCC) gene is a potential tumor-suppressor gene on chromosome 18q21.3. The relatively high frequency of loss of heterozygosity (LOH) and loss of expression of this gene in neuroblastoma, especially in the advanced stages, imply the possibility of involvement of the DCC gene in progression of neuroblastoma. However, only few typical mutations have been identified in this gene, indicating that other possible mechanisms for the inactivation of this gene may exist. A polymorphic change (Arg to Gly) at DCC codon 201 is related to advanced colorectal carcinoma and increases in the tumors with absent DCC protein expression. In order to understand whether this change is associated with the development or progression of neuroblastoma, we investigated codon 201 polymorphism of the DCC gene in 102 primary neuroblastomas by polymerase chain reaction single-strand conformation polymorphism. We found no missense or nonsense mutations, but a polymorphic change from CGA (Arg) to GGA (Gly) at codon 201 resulting in three types of polymorphism: codon 201(Gly) type, codon 201(Arg/Gly) type, and codon 201(Arg) type. The codon 201(Gly) type occurred more frequently in disseminated (stages IV and IVs) neuroblastomas (72%) than in localized (stages I, II, and III) tumors (48%) (P=.035), and normal controls (38%) (P=.024). In addition, the codon 201(Gly) type was significantly more common in tumors found clinically (65%) than in those found by mass screening (35%) (P=.002). The results suggested that the codon 201(Gly) type of the DCC gene might be associated with a higher risk of disseminating neuroblastoma.

Alterations of the tumour suppressor gene DCC in neuroblastoma.

The deleted in colorectal carcinoma (DCC) gene, a candidate tumour suppressor, might be inactivated in a number of human cancers. In order to evaluate the possible role of DCC alterations in the pathogenesis of neuroblastoma, we examined 25 neuroblastoma cell lines and 16 primary tumours, including 6 samples with loss of heterozygosity (LOH) at the DCC locus for DCC mRNA expression, by using the reverse transcriptase-polymerase chain reaction (RT-PCR) technique. The level of DCC expression was significantly reduced or undetectable in 12 of 25 (48%) cell lines and 7 of 16 (44%) primary tumours, suggesting that inactivation of the DCC gene is involved in the development of neuroblastoma. Three of the 6 tumours with LOH at the DCC locus revealed reduced DCC mRNA expression, indicating that LOH at the DCC locus might have affected the levels of DCC mRNA. We also screened for mutations in 4 exons of the DCC gene in 12 cell lines by using PCR-single strand conformation polymorphism (PCR-SSCP) analysis. Point mutations were not found except a polymorphic change at codon 201. The mechanism for inactivation of the DCC gene will be further investigated.

Hypermethylation of p16 and p15 genes and RB protein expression in acute leukemia.

Both p16 and p15, encoded by genes located on chromosome 9p21, are inhibitors of cyclin-dependent kinases 4/6 (CDK4/6) and upstream regulators of RB function, and set up the RB/p16 tumor suppressive pathway, which is abrogated frequently in human neoplasms, either through inactivation of the RB or p16 tumor-suppressor protein, or alteration of the cyclin D1 or CDK4 oncoproteins. In hematological malignancies, deletion of p16/p15 locus has been shown to be highly specific to lymphoid malignancies, and more particularly to T-cell acute lymphoblastic leukemia (T-ALL). However, in the other subsets of ALL, deletions of p16 and p15 are relatively rare events. To investigate whether these genes are inactivated by methylation of the 5' CpG islands, we examined 35 leukemia cell lines and 29 childhood acute myeloid leukemia (AML) patients by Southern blot, polymerase chain reaction (PCR) and Western blot analyses. We found methylation of p16 in 12 (50%) of 24 ALL cell lines, 5 (50%) of 10 AML cell lines without homozygous deletion of p16, and 11 (38%) of 29 AML patients. Those leukemia cell lines subjected to p16 methylation were found to have lost p16 protein expression. The p15 gene was methylated in 10 (34%) of 29 ALL cell lines, 6 (60%) of 10 AML cell lines without homozygous deletion of p15, and 15 (52%) of 29 AML patients. These results revealed the frequent methylation of p16 and p15 genes in B-ALL and AML despite a low frequency of p16 and p15 deletions and mutations in these leukemias. In the study for expression of RB protein, we found no expression of RB in 4 of 16 leukemia cell lines. Inactivation of the p16 gene was found in all the cell lines with expression of RB. Neither amplification nor rearrangement of cyclin D1 gene was found in any cell lines. These results suggest that inactivation of p16 and p15 genes is one of the most common genetic events in acute leukemia, and plays an important role for the RB/p16 pathway in the pathogenesis of acute leukemia.

Mutations of the RAS genes in childhood acute myeloid leukemia, myelodysplastic syndrome and juvenile chronic myelocytic leukemia.

Using the polymerase chain reaction-single strand conformation polymorphism method and direct sequencing, 12 acute myeloid leukemia (AML) cell lines and 108 fresh childhood myeloid tumor specimens, including 67 AML, 29 myelodysplastic syndrome (MDS), and 12 juvenile chronic myelocytic leukemia (JCML) were examined for mutation in H-, K-, and N-RAS genes. The mutation was found in eight of the 120 samples (6.7%), which consisted of four cell lines (33.3%) and four fresh myeloid tumors (3.7%). The frequency of the mutation in the cell lines was apparently higher than that in fresh myeloid tumors. K-RAS gene mutations were found in two of the 67 fresh AML specimens (3%). Interestingly, these two patients had 11q23 translocations. The N-RAS gene mutation was found in one of the 29 specimens (3.4%) of MDS and in one of the 12 specimens (8.3%) of JCML. All mutations were found in codon 12, 13 or 61 of the N-RAS and K-RAS genes. Frequency of mutation of RAS genes in fresh myeloid malignancies was very low. These findings suggest that mutation of RAS genes does not play an important role in the development of childhood myeloid malignancies.

Alterations of the p53, p21, p16, p15 and RAS genes in childhood T-cell acute lymphoblastic leukemia.

We investigated the alterations of the p53, p21, p16, p15 and RAS genes in childhood T-cell acute lymphoblastic leukemia (T-ALL) and T-ALL cell lines by polymerase chain reaction-single strand conformation polymorphism (PCR-SSCP) analysis and direct sequencing. Mutations of the p53 gene were found in three of 57 (5%) patients at diagnosis, one of 14 (7%) patients at relapse and in 12 of 18 (67%) cell lines. In these 12 cell lines, four had more than two mutations of the p53 gene. The p53 mutations were found in four of five cell lines whose original fresh leukemic cells were simultaneously examined original fresh leukemic cells. However, only one of the four fresh leukemic cells had the same mutation. All patients with p53 mutations in the course of disease died. Mutations of the p21 gene were not identified in 71 fresh samples and in 18 cell lines. N-RAS mutations were found in two of 57 (4%) fresh T-ALL patients at diagnosis, and four of 18 cell lines (22%), whereas no mutations were detected in any samples at relapse. Alterations of the p16 gene were found in 18 of 47 (38%) patients at diagnosis and in seven of 14 (50%) at relapse. These differences were not statistically significant. There were no differences in the frequency of alteration of the p16 and p15 genes between event-free patients and the remaining patients. Furthermore, we found the methylation of p16 gene in three of seven patients lacking homozygous deletions, suggesting higher frequency of p16 inactivation than previous reports in T-ALL. Interestingly, we found that one allele is inactivated by methylation and another allele had nonsense mutation in one cell line (KOPT-KI), resulting in loss of protein expression of p16. This type of p16 inactivation has not been so far reported in leukemia. We conclude that, (1) p53 mutations are infrequent at diagnosis but tend to be associated with poor clinical outcome; (2) RAS and p21 mutations may not be involved in the pathogenesis of T-ALL; (3) not only frequent alterations of p16 and p15 genes but also methylation of p16 gene are involved in initiating the leukemogenesis of T-ALLs, and (4) these 5 genes are independently involved in T-ALL.

Acute nonlymphocytic leukemia showing abnormal nuclear lobulation.

An ultrastructural study of four cases of acute nonlymphocytic leukemia with abnormal nuclear lobulation was done. These cases were classified as M3 (Case 1), M3 variant (Cases 2 and 3), and M5, differentiated type (Case 4), on the basis of light microscopy according to the FAB classification. Ultrastructural observation of the leukemic cells of Cases 2 and 3 showed large bundles of fibrils in addition to abnormalities in the endoplasmic reticulum and granules, as had been reported in cases of acute promyelocytic leukemia. Large bundles of fibrils and abnormal nuclear lobulation also seemed to be characteristic of the M3 variant. However, the relationship between these structures was not identified. The exact nature of nuclear lobulation is not known, but seems to be related to some kind of intrinsic force and may be a presentation of the premature occurrence of lobulation intrinsic to the granulocyte or monocyte nucleus.

Ultrastructural studies of peripheral blood of neonates with Down's syndrome and transient abnormal myelopoiesis.

Ultrastructural studies were performed on blood samples from five neonates with Down's syndrome and transient abnormal myelopoiesis (TAM). Three methods of fixation were employed to detect diaminobenzidine (DAB) reactivity. The first method used glutaraldehyde solution, while the second and third methods used tannic acid-glutaraldehyde mixtures. Before fixation by the second method, specimens were washed in order to eliminate plasma, and before fixation by the third were diluted to lessen the effects of plasma protein. The latter two methods were more sensitive than the first for detection of DAB reactivity, while the third also resulted in better preservation of morphology than did the second. Even the first method was able to detect DAB reactivity in cells of megakaryocyte-platelet series in appropriate sections. Although the majority of blasts appeared with light microscopy to be undifferentiated, their ultrastructural morphology and ultrastructural cytochemistry were in fact found to be quite heterogeneous, consisting of cells of the megakaryocyte-platelet and granulocytic series, including basophils, and erythroid precursors. This finding supported the view that TAM was the result of unstable hematopoiesis rather than true leukemia.

Deficient activity of von Willebrand factor-cleaving protease in patients with Upshaw-Schulman syndrome.

We identified unusually large von Willebrand factor (vWF) multimers caused by deficient activity of vWF-cleaving protease in 2 patients with Upshaw-Schulman syndrome. The autoantibodies that inhibited the protease activity were not detected in the plasma of either patient. Periodic fresh-frozen plasma transfusion was effective for management of the hemolysis and thrombocytopenia. We detected enriched enzyme activity in a particular plasma fraction, although molecular cloning of this specific protease is needed to determine a more detailed pathogenesis and to develop new therapeutic approaches.

A prospective, randomized trial of conventional, dose-accelerated corticosteroids and intravenous immunoglobulin in children with newly diagnosed idiopathic thrombocytopenic purpura.

To determine the minimal essential treatment for childhood acute idiopathic thrombocytopenic purpura (ITP), a prospective, randomized trial was conducted focusing on hemorrhagic manifestation as well as platelet count. Subjects with a platelet count of <10 x 10(3)/microL or 10 to 29 x 10(3)/microL and mucosal bleeding (group 1) were randomly assigned to receive intravenous immunoglobulin (IVIg) at 1 to 2 g/kg, conventional oral prednisolone (o-PSL) (2 mg/kg for 2 weeks). parenteral methylprednisolone (mPSL) (5 mg/kg for 5 days), or pulsed parenteral methylprednisolone (PmPSL) (30 mg/kg for 3 days). Subjects with a platelet count of 10 to 29 x 10(3)/microL without mucosal bleeding (group 2) were randomized to receive either o-PSL or no treatment. In subjects with a platelet count of 30 x 10(3)/microL or higher (group 3), patients undergoing no specific treatment were monitored. In group 1, IVIg offered faster platelet enhancement compared with o-PSL and mPSL, although neither mPSL no PmPSL showed any advantage, even over o-PSL. Platelet response was uniformly excellent when pretreatment platelet coun was > or = 10 x 10(3)/microL. Furthermore, the presence or absence of mucosal bleeding in subjects with a platelet count <10 x 10(3)/microL had no effect on the response to treatment. In group 2, platelet increase was indifferently attained with or without o-PSL. These data suggest that childhood acute ITP with a platelet count > or = 10 x 10(3)/microL may be left untreated or may be treated with o-PSL when mucosal bleeding is evident, whereas for those with a platelet count <10 x 10(3)/microL, IVIg is the most predictable platelet enhancer. Thus, a platelet count of 10 x 10(3)/microL seems to be informative enough to decide whether to treat childhood acute ITP.