BCL2 Inhibitor (ABT-737): A Restorer of Prednisolone Sensitivity in Early T-Cell Precursor-Acute Lymphoblastic Leukemia with High MEF2C Expression?

Early T-cell precursor-acute lymphoblastic leukemia (ETP-ALL) has been identified as a high-risk subtype of pediatric T-cell acute lymphoblastic leukemia (T-ALL). Conventional chemotherapy is not fully effective for this subtype of leukemia; therefore, potential therapeutic targets need to be explored. Analysis of the gene expression patterns of the transcription factors in pediatric T-ALL revealed that MEF2C and FLT3 were expressed at higher levels in ETP-ALL than typical T-ALL. Using human T-ALL and BaF3 cell lines with high expression levels of MEF2C, the present study tested whether the BCL2 inhibitor (ABT-737) restores the sensitivity to prednisolone (PSL), because MEF2C causes PSL resistance, possibly by augmenting the anti-apoptotic activity of BCL2. Treatment with PSL and ABT-737 caused a significant reduction in the IC50 of PSL in the MEF2C-expressing LOUCY cells, in addition to the MEF2C-transduced BaF3 cells, but not in the non-MEF2C-expressing Jurkat cells. The combination treatment significantly accelerated the killing of primary leukemic blast cells of ETP-ALL with high expression levels of MEF2C, which were co-cultured with murine stromal cells. These findings suggest that BCL2 inhibitors may be a therapeutic candidate in vivo for patients with ETP-ALL with high expression levels of MEF2C.

Integrated genetic and epigenetic analysis defines novel molecular subgroups in rhabdomyosarcoma

Rhabdomyosarcoma (RMS) is the most common soft-tissue sarcoma in childhood. Here we studied 60 RMSs using whole-exome/-transcriptome sequencing, copy number (CN) and DNA methylome analyses to unravel the genetic/epigenetic basis of RMS. On the basis of methylation patterns, RMS is clustered into four distinct subtypes, which exhibits remarkable correlation with mutation/CN profiles, histological phenotypes and clinical behaviours. A1 and A2 subtypes, especially A1, largely correspond to alveolar histology with frequent PAX3/7 fusions and alterations in cell cycle regulators. In contrast, mostly showing embryonal histology, both E1 and E2 subtypes are characterized by high frequency of CN alterations and/or allelic imbalances, FGFR4/RAS/AKT pathway mutations and PTEN mutations/methylation and in E2, also by p53 inactivation. Despite the better prognosis of embryonal RMS, patients in the E2 are likely to have a poor prognosis. Our results highlight the close relationships of the methylation status and gene mutations with the biological behaviour in RMS.

Hematopoietic stem cell transplantation-associated thrombotic microangiopathy accompanied by renal arteriolar C4d deposition

HSCT-associated thrombotic microangiopathy (TA-TMA) is a severe complication with a poor prognosis. Recently, it has been reported that complement system dysregulation, such as CFH autoantibodies and deletions CFH-related genes 3 and 1, induced TA-TMA. In addition, C4d-positive renal arterioles are both a good marker of complement system activation and a useful diagnostic tool for TA-TMA. Because dysregulation of the complement system is associated with TA-TMA, the complement system might be a therapeutic target, such as eculizumab, a terminal complement inhibitor. Herein, we describe an eight-yr-old boy who developed TA-TMA accompanied by severe renal dysfunction. His renal specimen showed diffuse C4d deposition in the renal arterioles, which is consistent with TA-TMA. Although the patient gradually improved without eculizumab, renal arteriolar C4d staining in sample with TA-TMA shows the complement system activation and may guide the target therapy using the eculizumab.

FN1: a novel fusion partner of ALK in an inflammatory myofibroblastic tumor

Inflammatory myofibroblastic tumors (IMTs) are rare tumors characterized as low-to-intermediate grade sarcomas. Rearrangements of the anaplastic lymphoma kinase (ALK) gene have been reported in IMT. Here, we describe a novel fusion gene in an IMT tumor specimen. A 12-year-old male was admitted to our hospital with a bladder tumor. We identified the fibronectin 1 gene (FN1) as a fusion partner of ALK using 5'RACE. This novel fusion, FN1-ALK, resulted in ALK overexpression in the IMT. This finding should clarify the causes of IMT and facilitate development of novel therapeutics.

Modeling the early phenotype at the neuromuscular junction of spinal muscular atrophy using patient-derived iPSCs

Spinal muscular atrophy (SMA) is a neuromuscular disorder caused by mutations of the survival of motor neuron 1 (SMN1) gene. In the pathogenesis of SMA, pathological changes of the neuromuscular junction (NMJ) precede the motor neuronal loss. Therefore, it is critical to evaluate the NMJ formed by SMA patients' motor neurons (MNs), and to identify drugs that can restore the normal condition. We generated NMJ-like structures using MNs derived from SMA patient-specific induced pluripotent stem cells (iPSCs), and found that the clustering of the acetylcholine receptor (AChR) is significantly impaired. Valproic acid and antisense oligonucleotide treatment ameliorated the AChR clustering defects, leading to an increase in the level of full-length SMN transcripts. Thus, the current in vitro model of AChR clustering using SMA patient-derived iPSCs is useful to dissect the pathophysiological mechanisms underlying the development of SMA, and to evaluate the efficacy of new therapeutic approaches.

Successful treatment of idiopathic colitis related to XIAP deficiency with allo-HSCT using reduced-intensity conditioning

Recently, it has been reported that Crohn's-like intractable colitis occurred in approximately 20% of the patients with XIAP deficiency, also known as X-linked lymphoproliferative disease type 2. Because treatment used for Crohn's disease is not always effective for Crohn's-like colitis related to XIAP deficiency, more effective treatment should be established. Although several studies reported allo-HSCT might be promising even for Crohn's-like colitis related to XIAP deficiency, the outcome of allo-HSCT using MAC for XIAP deficiency is extremely poor due to frequent TRM. In addition, there is little information about the outcome of allo-HSCT for intractable colitis related to XIAP deficiency. Herein, we describe a patient with intractable colitis related to XIAP deficiency who was successfully treated with allo-HSCT using a reduced-intensity conditioning regimen. Although allo-HSCT using the RIC regimen might be a curative therapeutic option for intractable colitis with XIAP deficiency, the prognostic factors that will determine the success of allo-HSCT require further clinical information of more patients.

Low-grade intraventricular hemorrhage disrupts cerebellar white matter in preterm infants: evidence from diffusion tensor imaging

INTRODUCTION

Recent diffusion tensor imaging (DTI) studies have demonstrated that leakage of hemosiderin into cerebrospinal fluid (CSF), which is caused by high-grade intraventricular hemorrhage (IVH), can affect cerebellar development in preterm born infants. However, a direct effect of low-grade IVH on cerebellar development is unknown. Thus, we evaluated the cerebellar and cerebral white matter (WM) of preterm infants with low-grade IVH.

METHODS

Using DTI tractography performed at term-equivalent age, we analyzed 42 infants who were born less than 30 weeks gestational age (GA) at birth (22 with low-grade IVH, 20 without). These infants were divided into two birth groups depending on GA, and we then compared the presence and absence of IVH which was diagnosed by cerebral ultrasound (CUS) within 10 days after birth or conventional magnetic resonance imaging (MRI) at term-equivalent age in each group. Fractional anisotropy (FA) and apparent diffusion coefficient (ADC) at the superior cerebellar peduncle (SCP), middle cerebellar peduncle (MCP), motor tract, and sensory tract were measured.

RESULTS

In the SCP, preterm born infants with IVH had lower FA values compared with infants without IVH. In particular, younger preterm birth with IVH had lower FA values in the SCP and motor tract and higher ADC values in the MCP.

CONCLUSION

Low-grade IVH impaired cerebellar and cerebral WM, especially in the SCP. Moreover, younger preterm infants exhibited greater disruptions to cerebellar WM and the motor tract than infants of older preterm birth.

Abstract 1001: CD146 is a novel marker of highly tumorigenic populations and a therapeutic target in malignant rhabdoid tumor

Background: Malignant rhabdoid tumor (MRT) is a rare, highly aggressive pediatric malignancy, particularly develops during infancy and early childhood. In contrast to significant advances in multimodality therapy for other pediatric malignancies, effective therapies for MRT have not been established. The origin of tumor cells in MRT has remained undetermined: however, MRT arises from various parts of body with some preference, eading to the hypothesis that MRT derives from neural crest or its derivatives. CD146 is a cell surface glycoprotein expressed by various neural crest-derived tissues, which has been expected to be a therapeutic target for immunotherapy against various CD146-expressing malignancies, such as melanoma and osteosarcoma. Objective: In the current study, we investigated (1) the expression of CD146 in MRT, (2) tumorigenic potential of CD146-expressing cells in MRT, (3) in vitro and in vivo effect of anti-CD146 neutralizing antibody against MRT, and (4) underlying molecular mechanisms involved in CD146 expression. Material and Method: The expression levels of CD146 in MRT cell lines and clinical samples were investigated by fluorescence-activated cell sorting (FACS) or immunohistochemical analyses. Tumor cells were then sorted by FACS according to the expression of CD146, and purified CD146+ and CD146- cells were characterized by colony-formation, sphere-formation, and invasion assays. In vivo tumorigenic potential was assessed by subcutaneous transplantation of the purified CD146+ and CD146- cells into NOD/Shi-scid, IL-2Rγnull (NOG) mice. We developed rabbit anti-CD146 neutralizing antibody to investigate the effect of blocking CD146 both in vitro and in vivo. DNA microarray was performed by using purified CD146+ and CD146- cells, and the association of candidate pathways was validated by shRNA silencing or treatment of the neutralizing antibody against CD146. Results: The expression of CD146 was observed in all MRT cell lines and clinical samples. Compared to CD146- cells, CD146+ cells in MRT exhibited significantly higher colony-, and sphere-forming potential, and more invasive capacity. The data of xeno-transplant demonstrated that stable engraftment of the purified tumor cells as well as successful engraftment after serial transplantation was exclusively observed in CD146+ cell-injected mice. Furthermore, our anti-CD146 neutralized antibody effectively inhibited both in vitro proliferation and in vivo tumor formation. Microarray analysis showed that various molecular pathways were engaged in higher tumorigeneity in CD146+ cells. Details of underlying mechanisms are now under investigation. Conclusion: Our data shows that CD146 defines a distinct subpopulation with highly tumorigenic and self-renewal capacity in MRT. Notable anti-tumor effect of anti-CD146 neutralizing antibody will facilitate a novel immunotherapy for MRT.

Citation Format: Seishiro Nodomi, Katsutsugu Umeda, Satoshi Saida, Yasumichi Kuwahara, Takayuki Hamabata, Tomoo Daifu, Itaru Kato, Hidefumi Hiramatsu, Ken-ichiro Watanabe, Souichi Adachi, Eiichi Konishi, Hajime Hosoi, Toshio Heike. CD146 is a novel marker of highly tumorigenic populations and a therapeutic target in malignant rhabdoid tumor. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1001. doi:10.1158/1538-7445.AM2014-1001

MRD detection of leukemia relapse using HLA typing by FACS in combination with FISH after mismatched allogeneic stem cell transplantation

Loss of mismatched HLA is a cause of relapse following HLA-mismatched allo-SCT. We directly detected the loss of mismatched HLA alleles in relapsed leukemic cells at a MRD level using HLA typing by multicolor FACS (HLA-Flow) in combination with FISH in the BM of two patients with MLL-AF9-positive AML, at 6 and 10 months after mismatched allo-SCT. HLA-Flow with FISH analysis detected relapsed leukemic cells not expressing a mismatched HLA allele and harboring the MLL rearrangement. Simultaneously, real-time quantitative RT-PCR detected a low copy number of MLL-AF9 transcripts, consistent with MRD detection. HLA-Flow with FISH is a powerful method for detecting molecular relapse after mismatched allo-SCT and provides important information on the HLA expression status of the relapsed leukemic cells to help determine the next intervention.

Identification of COL3A1 and RAB2A as novel translocation partner genes of PLAG1 in lipoblastoma

Lipoblastoma is a rapidly growing, benign neoplasm in children. Surgical excision is usually curative, with a recurrence rate of about 20%. Because the histology of lipoblastoma is heterogeneous and overlaps with other lipomatous tumors, some lipoblastoma cases have been difficult to diagnose. The detection of PLAG1 gene rearrangement is useful for the diagnosis of lipoblastoma. Three fusion partner genes are known in relation to PLAG1 in lipoblastoma HAS2 at 8q24.1, COL1A2 at 7q22, and RAD51L1 at 14q24. Herein, we describe another two novel fusion genes in lipoblastoma tumor specimens. We checked six tumors for the presence of two known fusion genes, HAS2-PLAG1 and COL1A2-PLAG1. Only HAS2-PLAG1 was found in one of the cases. Next, we attempted to identify potential PLAG1 fusion partners using 5'RACE. Sequence analysis revealed two novel fusion genes, COL3A1-PLAG1 in three cases and RAB2A-PLAG1 in one case, respectively. As a result of the translocations, the constitutively active promoter of the partner gene drives the ectopic expression of PLAG1. We also evaluated whether a high level of PLAG1 expression can be used to help differentiate lipomatous tumors. PLAG1 expression was evaluated by real-time PCR in five lipoblastoma tumor specimens. The expressions were 70-150 times higher in lipoblastomas than in human adipocytes. However, PLAG1 expression was low in one case of lipoma. These results demonstrate that PLAG1 overexpression is a potential marker of lipoblastoma. Our findings, in agreement with previous studies, show that lipoblastoma is a group of lipomatous tumors with PLAG1 rearrangement and overexpression. © 2014 Wiley Periodicals, Inc.

Miglitol increases energy expenditure by upregulating uncoupling protein 1 of brown adipose tissue and reduces obesity in dietary-induced obese mice

Background

Miglitol is an oral anti-diabetic drug that acts by inhibiting carbohydrate absorption in the small intestine. Recent studies have shown that miglitol reduces obesity in humans and rodents. However, its mechanisms have remained unclear. The purpose of this study was to determine whether miglitol generates heat by activating uncoupling protein 1 (UCP1), an enzyme involved in thermogenesis, in brown adipose tissue (BAT) in mice.

Methods

Four-week-old male C57BL/6 J mice were fed a high-fat diet alone (HF) or a high fat diet plus miglitol (HFM). Oxygen consumption (VO₂) was used to estimate metabolic rate. A thermal imaging camera was used to quantify heat generation from interscapular brown adipose tissue. We analyzed the protein and gene expressions of UCP1 and the expressions of four proteins related to β3-adrenergic signaling in the pathway activating UCP1 (protein kinase A (PKA), hormone-sensitive lipase (HSL), p38 α mitogen-activated protein kinase (p38αMAPK) and peroxisome proliferator-activated receptor gamma coactivator 1α (PGC1α)).

Results

At 8 weeks, body weight, epididymal and subcutaneous white adipose tissue and the HOMA-R value of the HFM mice were significantly less than those of the HF mice. Food intake was not different between the HF and HFM mice. VO₂ and BAT temperature were significantly higher in the HFM mice. Miglitol significantly enhanced the gene and protein expressions of UCP1 and the expressions of proteins related to β3-adrenergic signaling.

Conclusions

Miglitol’s anti-obesity effect was attributed to increased energy expenditure by upregulating UCP1 in BAT (i.e., by thermogenesis) and to enhancement of β3-adrenergic signaling in BAT.

Identification of the 12q15 amplicon within the homogeneously staining regions in the embryonal rhabdomyosarcoma cell line RMS-YM

Gene amplification represents one of the molecular mechanisms of oncogene overexpression in many types of tumors. Homogeneously staining regions (HSRs) are cytogenetic hallmarks of gene amplification. Rhabdomyosarcoma is the most common malignant soft-tissue tumor in children. RMS-YM is an embryonal rhabdomyosarcoma cell line that possesses 3 HSRs. This cytogenetic finding suggests the presence of gene amplifications associated with tumor development or progression in RMS-YM. Here, using fluorescence in situ hybridization, we detected high amplification of the MDM2 gene in the HSRs of RMS-YM. We also refined the region of the amplicon and identified that the FRS2 gene and others are amplified in RMS-YM. MDM2 and FRS2 play important roles as a regulator of p53 and a mediator of FGF signaling, respectively, and thus are potential molecular targets for therapy in many different tumors. RMS-YM may be useful for studies of the molecular pathways of tumorigenesis and tumor progression in rhabdomyosarcoma and for in vitro evaluation of newly developed therapeutic agents that target MDM2 or FRS2.

A MYCN-amplified cell line derived from a long-term event-free survivor among our sixteen established neuroblastoma cell lines

Although more than 110 neuroblastoma (NB) cell lines have been established, there have been neither reports on the rate of success to establish NB cell lines, nor well-documented NB cell lines from long-term-survivors. We attempted to establish NB cell lines from 114 patients. Sixteen NB cell lines were established from 12 patients. The success rates to establish cell lines were 1.4% (1/70) from patients in early stages, 25.0% (11/44) from those in advanced stages, and 10.5% (12/114) from those in all stages respectively. Eleven of these 12 patients eventually died. The surviving patient, who was in stage 4 with MYCN-amplification, has been event-free for 19 years after completing therapy. The serum MYCN DNA level in patient TK was very high before therapy, decreased after chemotherapy, and has remained at the normal levels until now. The gene expression profiling of the primary tumor and the K-N-TK cell line was analyzed with an NB-specific cDNA microarray, and indicated that the probability of 5-year survival was extremely low. Microarray-based comparative genomic hybridization (CGH) analysis indicated that genomic aberration profiles of the cell line were uncommon, with MYCN amplification, 17q gain and 11q loss. A unique KP-N-TK cell line, established from an event-free survivor, will be a useful tool for investigating how a patient can survive a tumor with an extremely poor prognosis.

Surgical strategies for unresectable hepatoblastomas

BACKGROUND

The aim of this study was to assess the surgical strategies for unresectable hepatoblastomas at the initial diagnosis based on the experience of two institutions.

METHODS

The PRETEXT (Pretreatment evaluation of tumor extent) and POST-TEXT (Post treatment extent of disease) staging, surgical treatments, and clinical outcomes were retrospectively analyzed for 12 cases with PRETEXT III or IV and M(-) of 29 hepatoblastomas treated based on the JPLT-2 (The Japanese Study Group for Pediatric Liver Tumor-2) protocol at two institutions between 1998 and 2011.

RESULTS

Two of the 9 cases with PRETEXT III status were downstaged to POST-TEXT II. One of the 3 cases with PRETEXT IV showed downstaging to POST-TEXT III. Four of the 7 cases with P2 or V3 (indicated for liver transplantation) in the PRETEXT staging system showed P2 or V3 in POST-TEXT staging after 2 cycles of CITA (JPLT-2 standard regimen), and one case showed P2 or V3 in POST-TEXT staging at the initial operation and underwent primary liver transplantation. The initial surgical treatments were 1 lobectomy, 2 segmentectomies, 6 trisegmentectomies, 2 mesohepatectomies, and 1 primary liver transplantation. Both patients who underwent mesohepatectomies had bile leakage, and 1 of 5 trisegmentectomies had an acute obstruction of the right hepatic vein. Two patients underwent rescue living donor liver transplantation. Both of these patients showed P2 or V3 positive findings in POST-TEXT staging after 2 cycles of CITA.

CONCLUSIONS

POST-TEXT staging and P and V factors should be evaluated after 2 cycles of CITA for unresectable hepatoblastomas detected at the initial diagnosis. The patients should be referred to the transplantation center if the POST-TEXT IV, P2, or V3 is positive at that time. Liver resection by trisegmentectomy is recommended in view of the incidence of surgical complications. Careful treatment, such as back-up transplantation, should thus be considered for liver resection in the cases with POST-TEXT IV, P2, or V3 status after initial 2 cycles of CITA.

Rapamycin inhibits substance P-induced protein synthesis and phosphorylation of PHAS-I (4E-BP1) and p70 S6 kinase (p70(S6K)) in human astrocytoma cells

The mitogenic substance P receptor (NK-1 subtype) is expressed in many primary human tumors with the highest frequency of expression appearing in astrocytomas and glioblastomas (75% and 100%, respectively). Recently, we showed that substance P neuropeptide induces DNA synthesis in the human astrocytoma U-373MG cells by activating the mitogen-activated protein (MAP) kinase pathway leading to the induction of c-Fos and c-Myc expression. The induction of these immediate early genes is necessary for the progression of cells form G1 to S phase of the cell cycle. In this study, we demonstrate that U-373MG cells are highly sensitive to the growth-inhibitory action of rapamycin at nanomolar concentrations (IC50 <1 ng/ml). We also show that SP peptide stimulates protein synthesis in the U-373MG cell line by activating a rapamycin-sensitive signaling pathway. Further, we demonstrate that SP is potent in stimulating PHAS-I protein (also known as 4E-BP1) phosphorylation and p70 S6 kinase (p70(S6K)) phosphorylation and enzymatic activity, and that this stimulation is inhibited by subnanomolar concentrations of rapamycin. In contrast, rapamycin was not at all effective in repressing SP-induced activation of MAP kinase pathway, c-Fos phosphoprotein expression, and DNA synthesis in U-373MG astrocytoma cells.