RNA-binding protein NOVA1 promotes acute T-lymphocyte leukemia progression by stabilizing USP44 mRNA.

Acute T-lymphocyte leukemia (T-ALL) is a malignant tumor disease. RNA-binding protein neotumor ventral antigen-1 (NOVA1) is highly expressed in bone marrow mononuclear cells of T-ALL patients, while the role of NOVA1 in T-ALL progression remains unknown. The gain- and loss-of-function studies for NOVA1 were performed in Jurkat and CCRF-CEM cells. NOVA1 overexpression promoted cell proliferation and cell cycle progression. NOVA1 knockdown increased the apoptosis rate of T-ALL cells. Ubiquitin-specific protease 44 (USP44), a nuclear protein with deubiquitinase catalytic activity, has been reported to play an oncogene role in human T-cell leukemia. USP44 expression was positively associated with NOVA1, and RNA immunoprecipitation assay verified the binding of NOVA1 to the mRNA of USP44. USP44 knockdown partially abolished NOVA1-induced cell proliferation and inhibition of apoptosis. The in vivo xenograft experiment was performed by injection of T-ALL tumor cells into the tail vein of NOD/SCID mice. The knockdown of NOVA1 had lower tumorigenicity. NOVA1 knockdown alleviated pathological changes in lung and spleen tissues, and increased the overall survival period and the weight of T-ALL mice. Thus, NOVA1 acts as an accelerator in T-ALL, and its function might be achieved by binding to and stabilizing USP44 mRNA.

USP44 accelerates the growth of T-cell acute lymphoblastic leukemia through interacting with WDR5 and repressing its ubiquitination.

T-cell acute lymphoblastic leukemia (T-ALL) is a common hematologic malignancy. Based on the data from GSE66638 and GSE141140, T-ALL patients depicted a higher USP44 level. However, its role in T-ALL is still unclear. In the present study, we investigated the role of USP44 in T-ALL growth. USP44 overexpression elevated the proliferation of CCRF-CEM cells, while USP44 knockdown suppressed the proliferation of Jurkat and MOLT-4 cells. In addition, USP44 accelerated the cell cycle progression, with boosted cyclinD and PCNA levels. However, USP44 knockdown induced apoptosis in Jurkat and MOLT-4 cells, with an upheaval among cleaved caspase-3 and PARP levels. Mechanistically, USP44 co-localized and interacted with WDR5, leading to the repression of its ubiquitination and degradation. Interestingly, WDR5 overexpression abolished the apoptosis induced by USP44 knockdown. Consistently, the in vivo study revealed that USP44 knockdown restricted the leukemic engraftments in the bone marrow and spleens and reduced the infiltration of T-ALL cells in the livers and lungs. In conclusion, this study indicated that USP44 enhanced the growth of T-ALL through interacting with WDR5 and repressing its ubiquitination. This study highlights the potential use of USP44 as a therapeutic target of T-ALL.

MicroRNA miR-188-5p as a mediator of long non-coding RNA MALAT1 regulates cell proliferation and apoptosis in multiple myeloma.

Multiple myeloma (MM), a malignancy of plasma cells mainly derived from the bone marrow, has remained incurable generally. LncRNA MALAT1 has been reported to be upregulated in the MM cells and knockdown of MALAT1 inhibited MM cell cycle progression and enhanced cell apoptosis. Online target prediction showed that two target sites for MALAT1 existed in miR-188-5p, which has been identified as a tumor suppressor in other types of cancers. However, the role of miR-188-5p in the MM and whether miR-188-5p mediates the MM tumor progression regulated by MALAT1 are still unknown. Herein, four main MM cell lines were adopted to investigate the effects of miR-188-5p on cell proliferation and apoptosis via transfection with miR-188-5p mimic/inhibitor and co-transfection with miR-188-5p inhibitor and MALAT1-shRNA plasmids. Xenograft tumor model was also established to study these effects in vivo. Overexpression of miR-188-5p inhibited cell viability, cell proliferation as well as tumor growth and arrested cell cycle at G1 to S transition, but miR-188-5p knockdown showed opposite effects on the MM cells in vitro and in vivo. Moreover, MALAT1 was shown to be inversely correlated with miR-188-5p expression through direct binding to miR-188-5p, and in turn, miR-188-5p could mediate the MM cell proliferation and apoptosis regulated by MALAT1. These findings indicate that miR-188-5p serves as a tumor suppressor in the progression of the MM and is directly involved in MM cell proliferation and apoptosis regulated by MALAT1, which may provide a potential therapeutic target or prognostic indictor for MM clinical treatment.

Chidamide induces necroptosis via regulation of c­FLIPL expression in Jurkat and HUT­78 cells.

T­cell acute lymphoblastic leukemia (T­ALL) is a hematopoietic malignancy, which is associated with a poor prognosis. It is difficult to achieve complete remission or long­term survival with conventional chemotherapy, partly due to decreased apoptosis. However, necroptosis can serve as an alternative pathway to induce cell death. The present study investigated whether the selective histone deacetylase (HDAC) inhibitor chidamide exerted a therapeutic effect on T­ALL and explored the underlying mechanism. The results revealed that HDAC expression was increased in Jurkat and HUT­78 cells treated compared with the control cell line (H9), and was accompanied by elevated cellular Fas­associated death domain­like interleukin­1ß converting enzyme inhibitory protein long form (c­FLIPL) levels. Chidamide treatment (2 µmol/l) also induced mitochondrial dysfunction, necroptosis and apoptosis in T­ALL cells in vitro. Furthermore, necroptosis was increased when apoptosis was blocked in T­ALL cells. Additionally, chidamide (2 µmol/l) downregulated c­FLIPL, HDAC1 and HDAC3 expression, and increased receptor­interacting protein kinase 3 expression and the phosphorylation of mixed lineage kinase domain­like pseudokinase in Jurkat and HUT­78 cells. The results obtained in the present study revealed that chidamide may induce necroptosis via regulation of c­FLIPL expression when apoptosis is inhibited in Jurkat and HUT­78 cells.

Silencing of Y-box binding protein-1 by RNA interference inhibits proliferation, invasion, and metastasis, and enhances sensitivity to cisplatin through NF-κB signaling pathway in human neuroblastoma SH-SY5Y cells.

Y-box binding protein-1 (YB-1), a member of Y-box protein family binding DNA and RNA, has been proposed as a novel marker in multiple malignant tumors and found to be associated with tumor malignancy. Neuroblastoma is an embryonal tumor arising from neuroblast cells of the autonomic nervous system, which is the most common cancer diagnosed in infants. It has been reported that YB-1 is highly expressing in various human tumors including nasopharynx, thyroid, lung, breast, colon, ovary, and prostate cancers. This study aimed to investigate the functional role of YB-1 in neuroblastoma by silencing YB-1 using RNA interference (shRNA) in neuroblastoma SH-SY5Y cells. We found that silencing of YB-1 decreased the proliferation, migration, and invasion of SH-SY5Y cells. At molecular level, inhibition of YB-1 decreased the expression level of PCNA as well as MMP-2 in neuroblastoma SH-SY5Y cells. Also, we discovered that YB-1 silencing sensitized SH-SY5Y cells to cisplatin and promoted the apoptosis induced by cisplatin due to down-regulation of multidrug resistance (MDR) 1 protein via NF-κB signaling pathway. Therefore, we consider that targeting YB-1 is promising for neuroblastoma treatment and for overcoming its cisplatin resistance in the development of new neuroblastoma therapeutic strategies.

Label-free quantitative proteomics reveals differentially expressed proteins in high risk childhood acute lymphoblastic leukemia.

Acute lymphoblastic leukemia (ALL) is the most common pediatric cancer. B-ALL is the most common type in pediatric ALL. Risk stratification is critical for setting on chemo-therapeutic regimen that has great impact on the survival rate. But the risk allocation schemas at present were not satisfied. We performed a proteomic study expecting to figure out the critical altered proteins which can indicate the risk rank. We depicted 86 differently expressed proteins in the high-risk childhood B-ALL, and 35 proteins were predicted to have directive interactions. We validated five identified proteins by immunoblot using specimens same as proteomics, and others different from that. We found the differently expressed proteins participated in pre-mRNA spicing, DNA damage response, and stress response which indicated different events happened in the high risk B-ALL. Our result provided new information for children B-ALL. It might aid more accurate risk stratification and might also be valuable to find new therapeutic targets. BIOLOGICAL SIGNIFICANCE: To our knowledge, this is the first proteomic analysis comparing the differentially expressed proteins between high risk and low risk of childhood B-ALL by a label-free quantitative proteomics. We found in high risk B-ALL, the aberrant evens happened in pre-mRNA splicing, DNA damage response, and stress response. This study reveals new insights in the high risk B-ALL, and might also be valuable to identify the high-risk more accurately, as well as to find new therapeutic targets.

[Research Progress of Necroptosis in Hematological Malignancies -Review].

Necroptosis is a novel programmed cell death mechanism which is characterized by a necrotic morphology, but the necroptosis is precisely regulated by cellular signaling pathway just like apoptosis. Recently, many reports have revealed that necroptosis contributes to the pathogenesis of inflammation, ischemic reperfusion injury and tumour. Hematological malignancies are a set of hemotopathy diseases with poor prognosis. In this review, the research progress of signaling pathway of necroptosis and its role in hematological malignancies are summarized.

shRNA-Mediated Silencing of Y-Box Binding Protein-1 (YB-1) Suppresses Growth of Neuroblastoma Cell SH-SY5Y In Vitro and In Vivo.

Y-box binding protein-1 (YB-1), a member of cold-shock protein superfamily, has been demonstrated to be associated with tumor malignancy, and is proposed as a prognostic marker in multiple carcinomas. However, the role of YB-1 in neuroblastoma has not been well studied. To investigate the functional role of YB-1 in neuroblastoma, we established a YB-1-silenced neuroblastoma cell strain by inhibiting YB-1 expression using a shRNA knockdown approach. YB-1-silenced neuroblastoma SH-SY5Y cells exhibited a pronounced reduction in cell proliferation and an increased rate of apoptosis in vitro and in vivo xenograft tumor model. At molecular level, YB-1 silencing resulted in downregulation of Cyclin A, Cyclin D1 and Bcl-2, as well as upregulated levels of Bax, cleaved caspase-3 and cleaved PARP-1. We further demonstrated that YB-1 transcriptionally regulated Cyclin D1 expression by chromatin-immunoprecipitation and luciferase reporter assays. In addition, xenograft tumors derived from neuroblastoma SH-SY5Y cell line were treated with YB-1 shRNA plasmids by intra-tumor injection, and YB-1 targeting effectively inhibited tumor growth and induced cell death. In summary, our findings suggest that YB-1 plays a critical role in neuroblastoma development, and it may serve as a potential target for neuroblastoma therapy.

Unc5D regulates p53-dependent apoptosis in neuroblastoma cells.

The mechanism of apoptosis via the p53­dependent pathway remains to be fully understood. In the present study, a novel p53 target gene, Unc5D, was identified and its possible function in human neuroblastoma cells was investigated. The apoptotic effects of Unc5D in SK­N­BE (p53­/­) and SH­SY5Y (p53+/+) cells were measured by an 3­(4,5­dimethylthiazol­2­yl)2,5­diphenyltetrazolium bromide solution assay. Reverse transcription­polymerase chain reaction (RT­PCR) was also performed to detect the endogenous expression of Unc5D. In H1299 (p53­/­) cells, following overexpression of p53, RT­PCR and western blot analysis were used to detect the Unc5D mRNA and protein levels. In order to detect the promoter activity in the Unc5D gene, a luciferase assay was performed. Finally, to confirm the activate site of p53 subsequent to DNA damage, western blot analysis was used to analyze the phosphorylation site of Unc5D stable and mock clones in H1299 cells by co­expression of p53. Unc5D­induced apoptosis may be largely dependent on the p53 status. Notably, Unc5D was found to be a direct transcriptional target of p53. During adriamycin­mediated apoptosis, Unc5D was significantly induced in p53­proficient SH­SY5Y cells but not in p53­deficient SK­N­BE cells. Overexpression of p53 resulted in an increase in the expression levels of endogenous Unc5D. Additionally, two elements were identified in the sequence of Unc5D. Notably, Unc5D expression also induced phosphorylation of p53 at serine­15. Unc5D is thus a newly identified transcriptional target of pro­apoptotic p53 and may also act upstream of p53 to induce p53­dependent apoptosis by phosphorylation at ser­15.

Overexpression of the dependence receptor UNC5H4 inhibits cell migration and invasion, and triggers apoptosis in neuroblastoma cell.

UNC5H4 is a newly identified member of the UNC5H receptor family. Previously, we have demonstrated that UNC5H4 expression is significantly higher in favorable neuroblastomas than in unfavorable ones, and higher UNC5H4 level is correlated with longer survival time. However, the function of UNC5H4 in the tumorigenesis of neuroblastoma still remains elusive. In the present study, the effects of UNC5H4 overexpression on neuroblastoma SH-SY5Y cells were investigated. We showed that enforced expression of UNC5H4 receptor significantly inhibited anchorage-dependent and anchorage-independent growth of SH-SY5Y cells. Cell migration and invasion of SH-SY5Y cells transfected with UNC5H4-expressing plasmid were obviously suppressed as compared to those transfected with emptor vector or non-transfected cells. Moreover, overexpression of UNC5H4 resulted in apoptosis in SH-SY5Y cells. The induction of apoptosis by UNC5H4 was completely abolished in the presence of its ligand, netrin-1. Finally, caspase cleavage and the presence of death domain were required for UNC5H4 to induce apoptosis in neuroblastoma SH-SY5Y cells. These data suggest that the dependence receptor UNC5H4 may act as a putative tumor suppressor in neuroblastoma.

Ursolic acid-induced apoptosis in K562 cells involving upregulation of PTEN gene expression and inactivation of the PI3K/Akt pathway.

Ursolic acid (UA), a pentacyclic triterpenoid derived from a variety of medicinal plants, exhibits potent anticancer activity against many types of cancer cells. However, the anticancer mechanism of UA is not clearly understood. Suppression of phosphatase and a tensin homolog deleted on chromosome 10 (PTEN) gene expression leading to activation of the phosphatidylinositol-3-OH kinase (PI3K)/Akt pathway has been observed in many cancers including leukemia, making the PTEN gene and PI3K/Akt pathway a central target for cancer therapy. Here, we demonstrated that UA was able to inhibit growth, induce apoptosis in a human chronic myelogenous leukemia cell line (K562 cells) via upregulation of PTEN gene expression, inhibit Akt kinase activity, change mitochondrial transmembrane potential and reduce the release of cytochrome c and the activity of caspases. These results suggest that UA may elicit its strong antitumor effects via upregulation of the PTEN gene and inhibition of the PI3K/Akt pathway.

[Efficacy, side effects and blood concentration monitoring of high-dose methotrexate in treatment of 180 children with acute lymphoblastic leukemia].

This study was purposed to investigate the effects of high-dose methotrexate (HD-MTX)-CF + VDT protocol on pediatric acute lymphoblastic leukemia (ALL) by means of retrospective analysis. MTX plasma concentration was dynamically detected and evaluated so as to avoid or reduce the side effects of HD-MTX, and adjust the time and dosage of calcium folinate (CF) or carry out the plasma exchange as occasion requires. Totally 180 cases of ALL were enrolled in this study, and received 380 administration of HD-MTX-CF + VDT protocol, including 122 patients with induction therapy as well as 58 cases during maintenance therapy, among which 68 cases were defined as low risk, 80 cases as middle risk and 32 cases as high risk. 2.0 g/m(2) MTX, 3.0 g/m(2) MTX, and 5.0 g/m(2) MTX were individually used according to low risk, middle risk or T immunohistochemical expression. The results indicated that 36.3% cases showed the side-effects of HD-MTX including mucocutaneous lesions, gastrointestinal reaction, hepatic dysfunction, renal damage, fever, myelosuppression, cardiotoxicity, infection and allergic response. All of these side effects were reversible through treatment. The elimination delay of MTX occurred in 110 cases, out of which 3 cases got MTX concentration > 10 µmol/L at 24 hours, 50 cases > 1.0 µmol/L at 44 hours, the remaining 57 cases > 0.1 µmol/L at 68 hours. CF dosage was adjusted according to the concentration of MTX until it was less than 0.1 µmol/L. 1 case had renal interstitial inflammation and acute renal failure, but finally he was cured. No patients received plasma exchange or died. It is concluded that the extramedullary leukemia control protocol, in which MTX is main drug, is effective therapy for obtaining long-term remission and event-free survival rate in ALL patients, but the side effects and risks increase along with the increase of MTX dose. The metabolic level of HD-MTX has found to be obvious individual, so the dynamic monitoring of MTX concentration in plasma and administration of proper dosage of CF are important factors for HD-MTX protocol application in ALL patients.

[Apoptosis of jurkat cells induced by ursolic acid and its mechanism].

The aim of this study was to investigate the apoptosis effect of Jurkat cells induced by ursolic acid (UA) and its molecular mechanism so as to provide the theoretical basis for treatment of hematological malignancies by using UA. The cytotoxic effect of different concentration UA on Jurkat cells and inhibitory effect of caspase-9 inhibitor on cytotoxicity of UA were assayed by using WST-8 method; the Jurkat cells treated with 20 or 40 micromol/L UA for 2 or 4 hours were collected and were stained by Annexin/PI, then the apoptosis rate of Jurkat cells was detected by flow cytometry; the Jurkat cells in logarithmic growth phase were collected after treatment with different concentrations of UA for different times, the cell protein was extracted, then the activation of caspase-9, -3 and cytochrome C as well as phosphorylation level of Akt were determined by Western blot. The results indicated that the cytotoxic effect of UA on Jurkat cells was significant. UA induced apoptosis of Jurkat cells. Caspase-9, caspase-3 and cytochrome C were activated, and the phosphorylation of Akt was inhibited in the Jurkat cell apoptosis process induced by UA. It is concluded that the UA shows significant cytotoxic effect on Jurkat cells, UA can induce apoptosis of Jurkat cells through the mitochondria pathway. The mechanism may be associated with the inhibition of Akt phosphorylation.