Kana Washio

Bio: Kana Washio is an academic researcher from Okayama University. The author has contributed to research in topics: Medicine & Hematopoietic stem cell transplantation. The author has an hindex of 7, co-authored 29 publications receiving 292 citations.

Activation of Akt is associated with poor prognosis and chemotherapeutic resistance in pediatric B-precursor acute lymphoblastic leukemia.

Abstract: Background Activation of the phosphoinositide 3-kinase (PI3K)/Akt pathway, a pro-survival pathway, plays important roles in tumor cell growth. However, the role of Akt in the pathogenesis of pediatric B-precursor acute lymphoblastic leukemia (B-pre ALL) remains to be clarified. This study was undertaken to explore the clinical relevance and molecular mechanisms underlying the activation of Akt (i.e., phosphorylated Akt, P-Akt) in pediatric B-pre ALL. Procedure We evaluated the activation status of Akt in bone marrow samples from 21 children with newly diagnosed B-pre ALL and correlated the expression level of P-Akt with clinicopathologic and prognostic features. Additionally, we transfected the myristoylated Akt cDNA into the B-pre ALL cell line, Nalm-6, and examined the effect, in vitro, of Akt activation on the response to antitumor drugs. Results P-Akt expression in B-pre ALL blast cells at diagnosis was associated significantly with poor response to induction chemotherapy including prednisolone, dexamethasone, vincristine, and adriamycin in B-pre ALL patients. Both overall survival and relapse-free survival in patients with P-Akt expression were reduced significantly more than in patients without P-Akt expression. Activation of Akt reduced the extent of apoptosis induced by the antitumor drugs in Nalm-6 listed above. Activation of Akt did not induce expression of P-glycoprotein, a drug transporter that is capable of conferring multidrug resistance. Conclusion These results support the contention that Akt activation is a mechanism of chemotherapeutic resistance in B-pre ALL and suggest that Akt can be a therapeutic target for the treatment of relapsed or refractory pediatric B-pre ALL. Pediatr Blood Cancer 2012; 59: 83–89. © 2011 Wiley Periodicals, Inc.

Accumulation of aberrant CpG hypermethylation by Helicobacter pylori infection promotes development and progression of gastric MALT lymphoma.

Abstract: Aberrant DNA hypermethylation is an important mechanism for the inactivation of tumor-related genes in human tumors. Gastric mucosa-associated lymphoid tissue (MALT) lymphomas arise from Helicobacter pylori-associated chronic gastritis; most patients are H. pylori-positive and eradication therapy is highly effective. In the present study, we used methylation-specific PCR to analyze the DNA methylation status of 11 tumor-related genes (Kip2, p16, hMLH-1, p15, p73, MGMT, DAPK, MINT1, MINT2, MINT31 and HCAD) in 21 specimens of MALT lymphoma, 5 specimens of MALT lymphoma with large cell component (high-grade MALT lymphoma), 15 specimens of diffuse large B-cell lymphoma (DLBCL), 8 specimens of complete remission of MALT lymphoma after eradication therapy, 5 specimens with no evidence of malignancy and PBMCs from 10 healthy donors. The average number of methylated genes was significantly greater in gastric lymphomas as compared to normal controls (P<0.001). The CpG island methylator phenotype (CIMP) was observed in 93.3% (14/15) of DLBCLs, 100% (5/5) of high-grade MALT lymphomas and 61.9% (13/21) of MALT lymphomas; in contrast, CIMP was not found in the control group (0%). The average number of methylated genes and the CIMP incidence significantly increased with H. pylori infection. Furthermore, aberrant CpG methylation of specific genes, such as p16, MGMT and MINT31, was consistently associated with H. pylori infection. These findings strongly suggest that H. pylori infection causes the aberrant DNA hypermethylation of specific genes and induces CIMP, which is an important epigenetic mechanism for the development and progression of gastric MALT lymphoma; additionally, our findings provide new epigenetic markers.

Multi-Step Aberrant CpG Island Hyper-Methylation Is Associated with the Progression of Adult T–Cell Leukemia/Lymphoma

Abstract: Aberrant CpG island methylation contributes to the pathogenesis of various malignancies. However, little is known about the association of epigenetic abnormalities with multistep tumorigenic events in adult T cell leukemia/lymphoma (ATLL). To determine whether epigenetic abnormalities induce the progression of ATLL, we analyzed the methylation profiles of the SHP1, p15, p16, p73, HCAD, DAPK, hMLH-1, and MGMT genes by methylation specific PCR assay in 65 cases with ATLL patients. The number of CpG island methylated genes increased with disease progression and aberrant hypermethylation in specific genes was detected even in HTLV-1 carriers and correlated with progression to ATLL. The CpG island methylator phenotype (CIMP) was observed most frequently in lymphoma type ATLL and was also closely associated with the progression and crisis of ATLL. The high number of methylated genes and increase of CIMP incidence were shown to be unfavorable prognostic factors and correlated with a shorter overall survival by Kaplan-Meyer analysis. The present findings strongly suggest that the multistep accumulation of aberrant CpG methylation in specific target genes and the presence of CIMP are deeply involved in the crisis, progression, and prognosis of ATLL, as well as indicate the value of CpG methylation and CIMP for new diagnostic and prognostic biomarkers.

High-grade glioneuronal tumor with an ARHGEF2-NTRK1 fusion gene.

Abstract: Here, we report a highly unusual case of high-grade glioneuronal tumor with a neurotrophic tropomyosin receptor kinase (NTRK) fusion gene. A 13-year-old girl presented with headache and vomiting and MRI detected two cystic lesions bilaterally in the frontal areas with surrounding edema. The left larger tumor was removed by left frontal craniotomy. The tumor was diagnosed as a high-grade glioneuronal tumor, unclassified. Methylation profiling classified it as a diffuse leptomeningeal glioneuronal tumor (DLGNT) with low confidence. This tumor showed genotypes frequently found in DLGNT such as 1p/19q codeletion without IDH mutation and, however, did not have the typical DLGNT clinical and histological features. RNA sequencing identified an ARHGEF2 (encoding Rho/Rac guanine nucleotide exchange factor 2)-NTRK1 fusion gene. The presence of recurrent NTRK fusion in glioneuronal tumors has an important implication in the clinical decision making and opens up a possibility of novel targeted therapy.

High rates of ovarian function preservation after hematopoietic cell transplantation with melphalan-based reduced intensity conditioning for pediatric acute leukemia: an analysis from the Japan Association of Childhood Leukemia Study (JACLS)

Abstract: Women are at high risk of hypergonadotropic hypogonadism after hematopoietic cell transplantation (HCT). Hypogonadism is universal after irradiation or busulfan. We hypothesized that reduced intensity conditioning (RIC) might protect ovarian function after HCT. We retrospectively reviewed data from patients with acute leukemia treated according to the Japan Association of Childhood Leukemia Study and nationwide multicenter study protocol. We selected 11 female patients with acute leukemia who received first HCT with RIC, had survived for three or more years after HCT, and were aged ≥ 12 years at the last follow-up visit. Median age at diagnosis, HCT, and last visit were 8, 10, and 17 years. Six patients received HLA-matched bone marrow (BM), two HLA-mismatched BM, and three cord blood. Melphalan was used as conditioning regimen in all patients. At the last visit, six of seven post-pubertal patients at transplantation recovered menstruation, and four of four patients who underwent transplantation at the pre-pubertal began menstruation. Height z scores showed no significant reduction between pre-transplant and post-transplant. No patients received growth hormone treatment. Only one recipient displayed subclinical hypothyroidism. Melphalan-based RIC may be an encouraging option for patients with acute leukemia to avoid ovarian and endocrine dysfunction after HCT.

Epigenetic modifications as therapeutic targets

Abstract: Epigenetic modifications work in concert with genetic mechanisms to regulate transcriptional activity in normal tissues and are often dysregulated in disease. Although they are somatically heritable, modifications of DNA and histones are also reversible, making them good targets for therapeutic intervention. Epigenetic changes often precede disease pathology, making them valuable diagnostic indicators for disease risk or prognostic indicators for disease progression. Several inhibitors of histone deacetylation or DNA methylation are approved for hematological malignancies by the US Food and Drug Administration and have been in clinical use for several years. More recently, histone methylation and microRNA expression have gained attention as potential therapeutic targets. The presence of multiple epigenetic aberrations within malignant tissue and the abilities of cells to develop resistance suggest that epigenetic therapies are most beneficial when combined with other anticancer strategies, such as signal transduction inhibitors or cytotoxic treatments. A key challenge for future epigenetic therapies will be to develop inhibitors with specificity to particular regions of chromosomes, thereby potentially reducing side effects.

Priming of protective T cell responses against virus-induced tumors in mice with human immune system components.

Abstract: Many pathogens that cause human disease infect only humans. To identify the mechanisms of immune protection against these pathogens and also to evaluate promising vaccine candidates, a small animal model would be desirable. We demonstrate that primary T cell responses in mice with reconstituted human immune system components control infection with the oncogenic and persistent Epstein-Barr virus (EBV). These cytotoxic and interferon-γ–producing T cell responses were human leukocyte antigen (HLA) restricted and specific for EBV-derived peptides. In HLA-A2 transgenic animals and similar to human EBV carriers, T cell responses against lytic EBV antigens dominated over recognition of latent EBV antigens. T cell depletion resulted in elevated viral loads and emergence of EBV-associated lymphoproliferative disease. Both loss of CD4+ and CD8+ T cells abolished immune control. Therefore, this mouse model recapitulates features of symptomatic primary EBV infection and generates T cell–mediated immune control that resists oncogenic transformation.