Coexpression of Wilms' tumor suppressor 1 (WT1) and androgen receptor (AR) in the genital tract of human male embryos and regulation of AR promoter activity by WT1

The Wilms' tumor suppressor 1 (WT1) is one of the key regulators of early male genital development. The androgen receptor (AR) is the major local factor responsible for the development of the male genitalia. As a subset of patients, with WT1 mutations and virilization defects, were found to present normal testosterone producing testes after birth, which suggests androgen resistance, we hypothesized that WT1 and AR might functionally interact during the development of the external genitalia. Coexpression of WT1 and AR was found in the mesenchyme surrounding the urogenital sinus, the mesonephros, and the Müllerian duct at 7 weeks p.c. and in the epididimys, vas deferens, and the gubernaculum testes from 13 to 27 weeks p.c. in human male embryos. A modification of AR expression by WT1 (WT1+/+, WT1+/-, and WT1+/- R394W) was seen in CV1, Hela, LNCaP, and T293 cells. WT1 was shown to increase or decrease AR expression depending on the cell line (1.6- to 3.7-fold). In this study, we consider LNCaP and T293 cells as the most physiological cell system, as both originate from the human urogenital tract. In these cell lines, a repressional effect of the mutant WT1+/- R394W (0.5-fold) on AR expression in comparison to the wild-type WT1+/- could be demonstrated. From our data, we conclude that a functional interaction of WT1 and AR might play a role during the development of the male external genitalia, but as the regulatory effects were moderate most likely in concert with other local cofactors.     

Mutations in the Wilms' tumor gene WT1 in leukemias

The tissue-specific Wilms' tumor gene WT1 is expressed in a range of acute leukemias and hematopoietic cell lines. Using single-strand conformational polymorphism analysis, we have found mutations in the WT1 gene in 4 of 36 acute leukemias. WT1 mutations are found in 15% of cases of acute myeloid leukemia, in which they are associated with a poor response to chemotherapy. The mutations comprise small insertions in exons 1 and 7 and a nonsense mutation in exon 9. All are predicted to produce a truncated WT1 protein with absence or disruption of the zinc finger region. These are the first mutations in the WT1 gene to be described in sporadic leukemia.     

Induction of WT1 (Wilms' tumor gene)-specific cytotoxic T lymphocytes by WT1 peptide vaccine and the resultant cancer regression

The Wilms' tumor gene WT1 is overexpressed in leukemias and various types of solid tumors, and the WT1 protein was demonstrated to be an attractive target antigen for immunotherapy against these malignancies. Here, we report the outcome of a phase I clinical study of WT1 peptide-based immunotherapy for patients with breast or lung cancer, myelodysplastic syndrome, or acute myeloid leukemia. Patients were intradermally injected with an HLA-A*2402-restricted, natural, or modified 9-mer WT1 peptide emulsified with Montanide ISA51 adjuvant at 0.3, 1.0, or 3.0 mg per body at 2-week intervals, with toxicity and clinical and immunological responses as the principal endpoints. Twenty-six patients received one or more WT1 vaccinations, and 18 of the 26 patients completed WT1 vaccination protocol with three or more injections of WT1 peptides. Toxicity consisted only of local erythema at the WT1 vaccine injection sites in patients with breast or lung cancer or acute myeloid leukemia with adequate normal hematopoiesis, whereas severe leukocytopenia occurred in patients with myelodysplastic syndrome with abnormal hematopoiesis derived from WT1-expressing, transformed hematopoietic stem cells. Twelve of the 20 patients for whom the efficacy of WT1 vaccination could be assessed showed clinical responses such as reduction in leukemic blast cells or tumor sizes and/or tumor markers. A clear correlation was observed between an increase in the frequencies of WT1-specific cytotoxic T lymphocytes after WT1 vaccination and clinical responses. It was therefore demonstrated that WT1 vaccination could induce WT1-specific cytotoxic T lymphocytes and result in cancer regression without damage to normal tissues.     

WT1基因在白血病中的表达及临床意义

目的　探讨WT1基因在白血病中的作用。方法　用定量RT -PCR方法检测病人外周血或骨髓单个核细胞WT1mRNA表达。结果　 5 0例白血病患者中 ,41例WT1mRNA表达增高 ,阳性率为 82 0 %。急性髓细胞白血病 (AML)和急性淋巴细胞白血病 (ALL)阳性率分别为 84 0 %和 93 8% ,两组无显著差异 (P >0 0 5 ) ,慢性粒细胞白血病 (CML)的WT1mRNA阳性率为 6 6 7% ,其中慢性期均阴性 ,加速期和急变期均阳性。 17例完全缓解患者中 ,15例 (85 2 % )WT1mRNA转阴 ,复发患者WT1mRNA再次升高。结论　WT1mRNA表达的测定对白血病微小残留病检测具有重要意义     

白血病细胞系WT1的表达及反义核苷酸对其的抑制作用

目的:探讨RT-PCR方法测定白血病细胞系WT1基因的表达以及WT1反义寡核苷酸对白血病细胞系增殖的抑制作用。方法:应用RT-PCR方法测定K562、HL-60、TF-1及U937 4株白血病细胞系WT1基因的表达,然后应用针对WT1翻译起始位点的反义寡核苷酸(WT1 ASO)处理K562细胞系、U937细胞系,采用锥虫蓝拒染法确定白血病细胞的增殖。结果:K562、HL-60及TF-1 3株白血病细胞系均高度表达WT1,而U937细胞系未测到WT1。WT1 ASO能够抑制WT1表达阳性的K562细胞的生长,对WT1表达阴性的U937则无抑制作用;而WT1有义寡核苷酸对K562细胞系、U937细胞系均无抑制作用。结论:RT-PCR测定方法可以检测WT1基因在白血病细胞系表达,WT1反义寡核苷酸对白血病细胞有特异的抑制作用。WT1基因在白血病细胞增殖过程中起一定作用。     

Role of the WT1 tumor suppressor in murine hematopoiesis

The WT1 tumor-suppressor gene is expressed by many forms of acute myeloid leukemia. Inhibition of this expression can lead to the differentiation and reduced growth of leukemia cells and cell lines, suggesting that WT1 participates in regulating the proliferation of leukemic cells. However, the role of WT1 in normal hematopoiesis is not well understood. To investigate this question, we have used murine cells in which the WT1 gene has been inactivated by homologous recombination. We have found that cells lacking WT1 show deficits in hematopoietic stem cell function. Embryonic stem cells lacking WT1, although contributing efficiently to other organ systems, make only a minimal contribution to the hematopoietic system in chimeras, indicating that hematopoietic stem cells lacking WT1 compete poorly with healthy stem cells. In addition, fetal liver cells lacking WT1 have an approximately 75% reduction in erythroid blast-forming unit (BFU-E), erythroid colony-forming unit (CFU-E), and colony-forming unit-granulocyte macrophage-erythroid-megakaryocyte (CFU-GEMM). However, transplantation of fetal liver hematopoietic cells lacking WT1 will repopulate the hematopoietic system of an irradiated adult recipient in the absence of competition. We conclude that the absence of WT1 in hematopoietic cells leads to functional defects in growth potential that may be of consequence to leukemic cells that have alterations in the expression of WT1.     

Growth inhibition of human leukemic cells by WT1 (Wilms tumor gene) antisense oligodeoxynucleotides: implications for the involvement of WT1 in leukemogenesis

We have previously reported expression of WT1 in acute leukemia. To elucidate its biological significance, we examined the effect of the suppression of the WT1 expression by WT1 antisense oligomers on the growth of the leukemic cells expressing WT1. When 20 different WT1 antisense (AS) oligomers covering from the 5' cap sites of the WT1 gene to the 3' end were examined for the inhibitory effect on the growth of K562 cells expressing WT1, four WT1 AS oligomers inhibited the cell growth, whereas WT1 sense and random sequence oligomers had no effect on the cell growth of K562. Moreover, WT1 AS oligomers significantly inhibited the growth of the clonogenic cells of fresh leukemic cells in six of 14 patients with acute myeloid leukemia, in one of two patients with chronic myelogenous leukemia (CML) chronic phase, and in one of one patient with CML blastic crisis. However, these oligomers did not inhibit normal colony-forming unit-granulocyte-macrophage. Western blot analysis clearly demonstrated the significant reduction in the WT1 protein levels in the K562 and fresh leukemic cells that were treated with the WT1 AS oligomers, confirming that the inhibitory effect of the WT1 AS oligomers on the cell growth operates via the reduction in the WT1 protein levels. These results show that WT1 plays an important role in leukemogenesis.     

Expression and regulation of periostin/OSF-2 gene in rat uterus and human endometrium

Periostin/OSF2 is a ligand for alphavbeta3 and alphavbeta5 integrins and activates the Akt/PKB pathway. Recent reports of periostin/OSF2 gene disrupted mice indicate that periostin/OSF-2 plays an important role in implantation. Quantitative RT-PCR revealed that the expression of periostin/OSF-2 mRNA in rat uteri was reduced to approximately 10% at 12 h after 17beta-estradiol (E2) injection, but was not changed after progesterone (P) injection. RT-PCR revealed the expression of periostin/OSF-2 in human endometrium, cultured human endometrial stromal cells (ESCs), and cultured human endometrial epithelial cells. In ESCs, the expression of periostin/OSF-2 mRNA was reduced to approximately 50% at 6 h after E2 treatment. The amount of periostin/OSF2 mRNA in human endometrium significantly increased during mid-proliferative and early secretory phases of menstrual cycle, and decreased during late-proliferative, mid-secretory and late secretory phases. The expression of periostin/OSF2 mRNA significantly decreased in ESCs decidualized by treatment with E2 and P for 7 and 11 days. By immunohistochemistry, the expression of periostin/OSF-2 was strongly detected in endometrial stromal cells during early proliferative, mid-proliferative and early secretory phases, and was strongly detected in endometrial epithelial cells during late secretory phase. This study demonstrated that the expression of periostin/OSF-2 is regulated by ovarian steroid hormones in rat uterus and human endometrium.