Wilms' tumor gene (WT1) competes with differentiation-inducing signal in hematopoietic progenitor cells

The WT1 gene is a tumor-suppressor gene that was isolated as a gene responsible for Wilms' tumor, a childhood kidney neoplasm. We have previously reported that the WT1 gene is strongly expressed in leukemia cells with an increase in its expression levels at relapse and an inverse correlation between its expression levels and prognosis, thus making it a novel tumor marker for leukemic blast cells. Furthermore, WT1 antisense oligomers have been found to inhibit the growth of leukemic cells. These results strongly suggested the involvement of the WT1 gene in human leukemogenesis. The present study was performed to prove our hypothesis that the WT1 gene plays a key role in leukemogenesis and performs an oncogenic function in hematopoietic progenitor cells, rather than a tumor-suppressor gene function. 32D cl3, an interleukin-3-dependent myeloid progenitor cell line, differentiates into mature neutrophils in response to granulocyte colony-stimulating factor (G-CSF). However, when transfected wild-type WT1 gene was constitutively expressed in 32D cl3, the cells stopped differentiating and continued to proliferate in response to G-CSF. As for signal transduction mediated by G-CSF receptor (G-CSFR), Stat3alpha was constitutively activated in wild-type WT1-infected 32D cl3 in response to G-CSF, whereas, in WT1-uninfected 32D cl3, activation of Stat3alpha was only transient. However, most interesting was the fact that G-CSF stimulation resulted in constitutive activation of Stat3beta only in wild-type WT1-infected 32D cl3, but not in WT1-uninfected 32D cl3. Thus, WT1 expression constitutively activated both Stat3alpha and Stat3beta. A transient activation of Stat1 was detected in both wild-type WT1-infected and uninfected 32D cl3 after G-CSF stimulation, but no difference in its activation was found. No activation of MAP kinase was detected in both wild-type WT1-infected and uninfected 32D cl3 after G-CSF stimulation. These results demonstrated that WT1 expression competed with the differentiation-inducing signal mediated by G-CSFR and constitutively activated Stat3, resulting in the blocking of differentiation and subsequent proliferation. Therefore, the data presented here support our hypothesis that the WT1 gene plays an essential role in leukemogenesis and performs an oncogenic function in hematopoietic progenitor cells and represent the first demonstration of an important role of the WT1 gene in signal transduction in hematopoietic progenitor cells.

Successful donor leukocyte transfusion at molecular relapse for a patient with acute myeloid leukemia who was treated with allogenic bone marrow transplantation: importance of the monitoring of minimal residual disease by WT1 assay

We report here that a patient with relapsed AML after allogeneic bone marrow transplantation achieved and maintained complete remission (CR) after effective donor leukocyte transfusion (DLT), without the occurrence of GVHD and marrow aplasia, for more than 21 months. This continuous CR maintenance is mainly due to the application of DLT at molecular relapse that was diagnosed by monitoring minimal residual disease (MRD) by the quantitation of WT1 (Wilms tumor gene) expression levels (WT1 assay). The present case demonstrates that early application of DLT at molecular relapse is essential for the improvement of the efficacy of DLT for relapsed AML after BMT.

High incidence of chemotherapy-induced acral erythema in female patients with non-Hodgkin's lymphoma treated with the VACOP-B regimen

Seven patients, all females out of 29 with non-Hodgkin's lymphoma (NHL) (16 males and 13 females) treated with the VACOP-B regimen utilizing granulocyte-colony-stimulating factor (G-CSF) support developed chemotherapy-induced acral erythema (CAE). In contrast, none of 32 patients with NHL who were treated with CHOP, MACOP-B, or biweekly CHOP regimens without G-CSF developed CAE. Total dose intensities of VACOP-B regimen were higher than those of the three other regimens. However, no significant difference in dose intensities of each drug in the patients treated with the VACOP-B regimen was found between male and female patients and between female patients with or without CAE. The cause of the high incidence of CAE (7/13) in the female patients treated with VACOP-B regimen remains unknown. However, female sex hormones may increase susceptibility to CAE. Since the occurrence of CAE interrupts intensive chemotherapy and reduces the cure rate, high risk patients for CAE should be carefully monitored for early symptoms and signs of CAE and should be treated early and appropriately.

Murine long-term repopulating ability is compromised by ex vivo culture in serum-free medium despite preservation of committed progenitors

Hematopoietic progenitor cells can be maintained and expanded ex vivo in standard or serum-free culture medium supplemented with a variety of stimulatory cytokines. The use of serum-free medium allows specification of reproducible and precise growth conditions optimal for various applications and is more acceptable from a safety and regulatory point of view. Human and murine committed progenitor cells have been shown to be equivalently ro better supported by serum-free culture conditions in the presence of multicytokine combinations, but there is little information on the effects of such culture conditions on repopulating stem cells. We used a murine competitive repopulation model to assess the effect of serum-free versus serum-containing ex vivo culture on long-term reconstituting cells. Despite equivalent numbers of committed CFU-C and day 12 CFU-S present after 4 days of culture of murine marrow in serum-free or serum-containing conditions in the presence of IL-3, IL-6, and SCF, long-term reconstituting activity was significantly impaired by serum-free culture. These findings may have important implications for transplantation and gene therapy applications.

Transduction of hematopoietic stem cells in humans and in nonhuman primates

Primitive hematopoietic progenitor and stem cells have been pursued as highly desirable targets for genetic therapy. Retroviral vectors have been used for the majority of preclinical and clinical studies directed at these cells; however, both preclinical and early clinical studies indicate that the gene transfer efficiency of the current generation of vectors using known transduction conditions into primate and human repopulating stem cells is too low to be of clinical utility in most situations. In this presentation I will summarize the status of our completed and ongoing clinical genetic marking trials, and describe our efforts in the laboratory and use of primate transplantation models to improve on these results.

Hepatoid carcinoma of the lung with production of alpha-fetoprotein and abnormal prothrombin: an autopsy case report

Alpha-fetoprotein (AFP) is a useful tumor marker for the diagnosis of hepatic and testicular tumors. Several cases of AFP-producing lung cancer have been reported. We present here a patient with AFP-producing primary lung carcinoma, which showed high values of serum AFP (100,000 ng/mL). The concanavalin A nonbinding fraction rate of AFP was 15%. Gross and microscopic features of the lung carcinoma bore a striking resemblance to those of hepatocellular carcinoma. According to the histologic classification of lung tumor, this case was large cell carcinoma with prominent hepatoid differentiation. Immunohistochemically, we detected AFP in the cytoplasm of the neoplastic cells. We also detected another useful tumor marker for the diagnosis of hepatocellular carcinoma, i.e., des-gamma-carboxy prothrombin (protein induced by vitamin K absence or the absence of antagonist-II [PIVKA-II]), in serum using an enzyme immunoassay and in tumor cells by immunohistochemical analysis.

Prednisolone therapy for intra-abdominal desmoid tumors in a patient with familial adenomatous polyposis

The management of intra-abdominal desmoid tumors in patients with familial adenomatous polyposis (FAP) is very difficult. Non-steroidal anti-inflammatory drugs (NSAIDs), anti-estrogenic agents, and steroids are most commonly used, because surgical removal of these tumors may result in severe morbidity, with local recurrence being common. We report a patient with FAP and intra-abdominal desmoid tumors that regressed markedly after prednisolone therapy. The patient, a 38-year-old woman, had undergone total colectomy and ileorectal anastomosis with a diagnosis of FAP with colon cancer. Approximately 17 months after the surgery, she noticed an elastic firm lump in the abdominal wall. She also experienced lower abdominal distension. Computed tomography (CT) of the lower abdomen showed an invasive heterogenous low-density mass occupying the intra-abdominal space. She was treated with sulindac, NSAID, at 300 mg/day, the diagnosis being intra-abdominal desmoid tumors. She exhibited an intestinal obstruction about 9 months after the initiation of sulindac therapy. We changed the treatment and began prednisolone (initial dose, 40 mg/day). This treatment was continued for two years; subsequently, the lesions regressed markedly. She is currently well, more than 3 years after the withdrawal of prednisolone.

Aberrant overexpression of the Wilms tumor gene (WT1) in human leukemia

To clarify whether the expression of the WT1 gene in leukemic cells is aberrant or merely reflects that in normal counterparts, the expression levels of the WT1 gene were quantitated for normal hematopoietic progenitor cells. Bone marrow (BM) and umbilical cord blood (CB) cells were fluorescence-activated cell sorting (FACS)-sorted into CD34+ and CD34- cell populations, and the CD34+ cells into nine subsets (CD34+ CD33-, CD34+ CD33+, CD34+ CD38-, CD34+ CD38+, CD34+ HLA-DR-, CD34+ HLA-DR+, CD34+ c-kit(high), CD34+ c-kit(low), and CD34+ c-kit-) according to the expression levels of CD34, CD33, CD38, HLA-DR, and c-kit. Moreover, acute myeloid leukemic cells were also FACS-sorted into four populations (CD34+ CD33-, CD34+ CD33+, CD34- CD33+, and CD34- CD33-). FACS-sorted normal hematopoietic progenitor and leukemic cells and FACS-unsorted leukemic cells were examined for the WT1 expression by quantitative reverse transcriptase-polymerase chain reaction. The WT1 expression in the CD34+ and CD34- cell populations and in the nine CD34+ subsets of BM and CB was at either very low (1.0 to 2.4 x 10(-2)) or undetectable (< 10(-2)) levels (the WT1 expression level of K562 cells was defined as 1.0), whereas the average levels of WT1 expression in FACS-sorted and -unsorted leukemic cells were 2.4 to 9.3 x 10(-1). Thus, the WT1 expression levels in normal hematopoietic progenitor cells were at least 10 times less than those in leukemic cells. Therefore, we could not find any normal counterparts of BM or CB that expressed the WT1 at levels comparable with those in leukemic cells. These results indicate an aberrant overexpression of the WT1 gene in leukemic cells and imply the involvement of this gene in human leukemogenesis.

Lineage- and differentiation stage-specific expression of LSM-1 (LPAP), a possible substrate for CD45, in human hematopoietic cells

CD45, a transmembrane tyrosine phosphatase, is found on almost all nucleated hematopoietic cells and plays a crucial role in lymphocyte activation and differentiation. We recently achieved isolation of the human LSM-1 (hLSM-1) gene, whose product is a possible substrate for CD45, and we raised antibodies against the hLSM-1 protein. hLSM-1 expression in hematopoietic cells was examined with Northern and Western blot, fluorescence-activated cell sorter, and immunocytochemical analyses. It was found that in the lymphoid lineage, T and B lymphocytes as well as NK cells expressed LSM-1, whereas terminally differentiated plasma cells did not. As for the myeloid lineage, immature myeloid cells expressed LSM-1, whereas terminally differentiated granulocytes and monocytes did not. In the erythroid lineage, normal erythroblasts expressed very low levels of LSM-1, while erythroid cell lines (K562 and HEL) did not. Megakaryocytes did not express LSM-1. Both CD34+/CD33- and CD34+/CD33+ hematopoietic progenitor cells weakly expressed LSM-1. These results showed that LSM-1 is expressed in a lineage- and differentiation stage-specific fashion.

Differentiation of vaccine virus from field isolates of feline panleukopenia virus by polymerase chain reaction and restriction fragment length polymorphism analysis

In an attempt to distinguish feline panleukopenia virus (FPLV) live vaccine strains from FPLV field isolates in Japan, we compared restriction fragment length polymorphisms (RFLP) of polymerase chain reaction (PCR)-amplified fragments of live FPLV vaccine strains with those of FPLV Japanese field isolates. On the basis of nucleotide sequence differences between PLI-IV, a live vaccine strain, and FPV-483, a recent field isolate, two restriction enzymes, Dra I and Afa I, were selected for PCR-RFLP analysis of nucleotide (nt) differences at nt 3695 and 4508, respectively. Three live vaccine strains including the PLI-IV strain could be distinguished from the Japanese field isolates by their PCR-RFLP patterns by Afa I, but one live vaccine strain was indistinguishable from the Japanese isolates when Dra I and Afa I were used. The Japanese field isolates were divided into two groups by the profile of PCR-RFLP patterns generated by Dra I and Afa I, suggesting that PCR-RFLP analysis using several enzymes provides a good genetic estimate of strain differentiation. No isolate that shows a Dra I-negative/Afa I-negative pattern has emerged in Japan, indicating the possibility that the live vaccine viruses with a Dra I-negative/Afa I-negative pattern, such as the PLI-Iv strain, are candidates for use as live FPLV vaccine strain in Japan where they can be genetically distinguished from field strains.

Long-term follow-up of minimal residual disease in leukemia patients by monitoring WT1 (Wilms tumor gene) expression levels

Thirty-one patients (27 with acute myeloid leukemia [AML], 2 with acute lymphocytic leukemia [ALL], and 2 with acute mixed lineage leukemia [AMLL]) treated with conventional chemotherapy (CHT) and 23 patients (13 AML, 5 ALL, and 5 with chronic myeloid leukemia [CML]) treated with allogeneic bone marrow transplantation (BMT) were monitored for WT1 expression levels in BM and peripheral blood (PB) by reverse transcriptase-polymerase chain reaction over a long-term period (mean, 29 months for CHT and 24 months for BMT). Sixteen of the patients in the CHT group and 3 in the BMT group who had achieved complete remission suffered clinical relapse. In 10 of these patients, WT1 expression that had returned to normal BM levels (< 10(-3); the WT1 expression level of K562 cells was defined as 1.0) after complete remission (CR) either gradually or rapidly increased again to abnormal levels 1 to 18 months (mean, 7 months) before clinical relapse became apparent. In another 9 patients, WT1 expression never returned to normal BM levels even after CR and the subsequent relapse was accompanied by a rapid increase in WT1 expression to levels higher than 10(-2) (10(-3) levels in PB). On the other hand, the remaining 35 patients (15 CHT and 20 BMT) maintained their CR. In 29 of these patients (11 CHT and 18 BMT), WT1 expression either gradually or rapidly decreased to normal BM levels, whereas in the other 6 (4 CHT and 2 BMT), low or very low levels of WT1 mRNAs (10(-3) to 10(-2) in BM and 10(-5) to 10(-3) in PB) remain detectable, but without any clinical signs of relapse. A clear correlation was found to exist between the minimal residual disease (MRD) detected in the paired BM and PB samples for all types of leukemias (AML, ALL, and CML), with MRD in PB being approximately one-tenth of that in BM. WT1 quantitation of 168 paired BM and PB samples showed that PB samples were superior to BM samples for the detection of MRD. We conclude that monitoring of WT1 expression levels in BM and PB makes it possible to rapidly assess the effectiveness of individual treatment and diagnose clinical relapse in the early stage for all leukemia patients regardless of the presence or absence of tumor-specific DNA markers.

Measurement of cytokine levels by coronary sinus blood sampling during cardiac surgery with cardiopulmonary bypass

Interleukin-6, interleukin-8, and polymorphonuclear leukocyte elastase levels in coronary sinus blood were measured and compared with those in arterial blood drawn from the radial artery before and immediately after cardiopulmonary bypass (CPB) during coronary artery bypass grafting in 20 patients. We introduced coronary sinus blood sampling as a useful method for evaluation of myocardial metabolism, myocardial protection, and reperfusion injury during CPB, especially by measurement of cytokines. Because interleukin-6, interleukin-8, and polymorphonuclear leukocyte elastase are inflammatory mediators, we speculated that they might show higher levels in coronary sinus blood than in systemic arterial blood. The results obtained from the 20 patients showed that levels of interleukin-6, interleukin-8, and polymorphonuclear leukocyte elastase increased immediately after CPB (p < .01), but there was no significant difference in these levels between coronary sinus and systemic arterial blood. We conclude that the myocardium is not a predominant source of their release during CPB. Our results also showed that the measurement of these cytokines in systemic arterial blood reflected their levels in the whole body, including the myocardium, even during cardiac operation with CPB.

Maintenance of murine long-term repopulating stem cells in ex vivo culture is affected by modulation of transforming growth factor-beta but not macrophage inflammatory protein-1 alpha activities

Transforming growth factor-beta (TGF-beta) and macrophage inflammatory protein-l alpha (MIP-1 alpha) are both well-described inhibitors of committed and multipotential hematopoietic progenitors. The effect of these cytokines; on true stem cell activity in ex vivo culture systems as assayed by murine long-term repopulating activity (LTRA) has not been examined. We studied the stem cell effects of the addition of these cytokines to ex vivo cultures containing interleukin-3 (IL-3), IL-6, and stem cell factor (SCF), using the murine competitive repopulation assay. We also tested the impact of adding an anti-TGF-beta neutralizing antibody, to ask whether abrogation of autocrine/paracrine TGF-beta may protect or enhance the survival of LTRA during ex vivo culture. TGF-beta 1 had significant suppressive effects on both short- and long-term repopulating activities, and anti-TGF-beta antibody had enhancing effects compared with control cultures containing IL-3, IL-6, and SCF alone. MIP-1 alpha had no significant effects on either short- or long-term repopulating ability. These data suggest that abrogation of TGF-beta during suspension culture may allow enhanced survival or even expansion of primitive cells ex vivo, with implications for many applications, including gene therapy.

[Comparison between intermittent retrograde cold blood cardioplegia and retrograde crystalloid cardioplegia]

Intermittent retrograde cold blood cardioplegia was compared with retrograde crystalloid cardioplegia. Twenty-two adult patients underwent open heart surgery divided into two groups. Group BCP (n = 10) was protected with 15 degrees C blood containing potassium 15 mEq/l; Group CCP (n = 12) was protected with 4 degrees C St. Thomas' Hospital cardioplegic solution. Lactate, pyruvate, and CK-MB levels in coronary sinus blood were measured at 5 and 15 minutes after aortic unclamping and 5 minutes after weaning from cardiopulmonary bypass (CPB) in both groups. CPB time, cross-cross clamp time, incidence of postoperative low output syndrome and spontaneous return to sinus rhythm after aortic unclamping were not different between two groups. Cardiac index and pulmonary capillary wedge pressure measured immediately after weaning from CPB, were not different in both groups. Lactate level was significantly low in group BCP. Lactate uptaking ratio of myocardium was significantly high in group BCP. CK-MB levels were not different between two groups. Cold blood cardioplegia was seemed to provide better aerobic myocardial metabolism during aortic cross clamp. However, CK-MB levels and hemodynamic studies were not different.

The expression of IL-6 and its related genes in acute leukemia

Acute myeloid leukemia (AML) blast cells frequently produce interleukin-6 (IL-6) and other cytokines such as colony-stimulating factors (CSF: G-CSF, M-CSF, and GM-CSF), tumor necrosis factor (TNF)-alpha, and IL-1. The AML blast cells that produced IL-6 alone could not form autonomous in vitro colonies, whereas the blast cells that coexpressed CSF in addition to IL-6 were able to form such colonies. This suggests that IL-6 acts as a costimulator to enhance CSF-induced clonogenicity of AML blast cells. TNF-alpha and IL-1 that are produced from the blast cells may stimulate the growth of the AML blast cells by inducing production of CSF in bone marrow stromal cells or in the blast cell population itself. Improvement of clinical manifestations by the administration of an anti-IL-6 murine monoclonal antibody in a patient with AML-M5B confirmed an important role of IL-6 in in-vivo growth of the blast cells. The mRNA expression of IL-6 and its related genes in AML and acute lymphoid leukemia (ALL) blast cells was analyzed by reverse transcriptase-polymerase chain reaction (RT-PCR). IL-6 mRNA expression was common in AML, but rare in ALL, whereas the IL-6 receptor (IL-6R) mRNA was expressed in almost all cases of AML and in more than half of the cases of ALL. In contrast, gp130 was ubiquitously expressed in both AML and ALL. A significant correlation between the levels of IL-6R expression and the responsiveness of the blast cells to exogenous IL-6 was observed. This suggests the possibility of the rapid prediction of the responsiveness of leukemic cells to exogenous IL-6 (IL-6 administration for therapy) by rapid measurement of IL-6R mRNA by RT-PCR.