Histone deacetylase inhibitor chidamide regulates the Wnt/ß-catenin pathway by MYCN/DKK3 in B-ALL.

Our previous studies revealed that MYCN downregulates the expression of DKK3, activates the Wnt/ß-catenin signalling pathway at the transcriptional level, and thereby promotes the development of B cell acute lymphocytic leukaemia (B-ALL) but does not affect the methylation of the DKK3 promoter. Some studies have shown that MYCN is associated with histone acetylation. We speculate that histone deacetylase inhibitors (HDACis) can inhibit the Wnt/ß-catenin signalling pathway by inhibiting MYCN and increasing the expression of DKK3. Based on previous experiments, we tested this hypothesis by analysing the changes in MYCN, DKK3 and the Wnt/ß-catenin signalling pathways in B-ALL cells after treatment with the selective HDACi chidamide. The in vitro and in vivo experiments confirmed that chidamide inhibited the expression of MYCN and increased the expression of DKK3 by inhibiting the activity of histone deacetylase, and these effects resulted in inhibition of the Wnt/ß-catenin signalling pathway and the proliferation of B-ALL cells. These findings indicate that chidamide might be used alone or in combination with other chemotherapy regimens for patients with B-ALL and thus provide a new approach to the treatment of B-ALL.

Circular RNA regulatory network reveals cell-cell crosstalk in acute myeloid leukemia extramedullary infiltration.

BACKGROUND: Acute myeloid leukemia can develop as myoblasts infiltrate into organs and tissues anywhere other than the bone marrow, which called extramedullary infiltration (EMI), indicating a poor prognosis. Circular RNAs (circRNAs) are a novel class of non-coding RNAs that feature covalently closed continuous loops, suggesting their potential as micro RNA (miRNA) "sponges" that can participate in biological processes and pathogenesis. However, investigations on circRNAs in EMI were conducted rarely. In this study, the overall alterations of circRNAs and their regulatory network between EMI and non-EMI AML were delineated. METHODS: CircRNA and whole genome microarrays derived from EMI and non-EMI AML bone marrow mononuclear cells were carried out. Functional analysis was performed via Gene Ontology and KEGG test methods. The speculated functional roles of circRNAs were based on mRNAs and predicted miRNAs that played intermediate roles. Integrated bioinformatic analysis was conducted to further characterize the circRNA/miRNA/mRNA regulatory network and identify the functions of distinct circRNAs. The Cancer Genome Atlas (TCGA) data were acquired to evaluate the poor prognosis of distinct target genes of circRNAs. Reverse transcription-quantitative polymerase chain reaction was conducted to identify the expression of has_circRNA_0004520. Connectivity map (CMap) analysis was further performed to predict potential therapeutic agents for EMI. RESULTS: 253 circRNAs and 663 genes were upregulated and 259 circRNAs and 838 genes were downregulated in EMI compared to non-EMI AML samples. GO pathways were enriched in progress including cell adhesion (GO:0030155; GO:0007155), migration (GO:0016477; GO:0030334), signal transduction (GO:0009966; GO:0007165) and cell-cell communication. Overlapping circRNAs envolved in pathways related to regulate cell-cell crosstalk, 17 circRNAs were chosen based on their putative roles. 7 target genes of 17 circRNAs (LRRK1, PLXNB2, OLFML2A, LYPD5, APOL3, ZNF511, and ASB2) indicated a poor prognosis, while overexpression of PAPLN and NRXN3 indicated a better one based on data from TCGA. LY-294002, trichostatin A and SB-202190 were identified as therapeutic candidates for EMI by the CMap analysis. CONCLUSION: Taken together, this study reveals the overall alterations of circRNA and mRNA involved in EMI and suggests potential circRNAs may act as biomarkers and targets for early diagnosis and treatment of EMI.

Platelet-derived growth factor-B (PDGF-B) induced by hypoxia promotes the survival of pulmonary arterial endothelial cells through the PI3K/Akt/Stat3 pathway.

BACKGROUND/AIMS: Pulmonary arterial endothelial plexiform lesions are a basic pathological change associated with pulmonary vascular remodeling and are characterized by the formation of tumorlets as a result of over-growth of endothelial cells. Accumulating evidence suggests that platelet-derived growth factor (PDGF) participates in regulating the progression of pulmonary arterial hypertension. However, whether PDGF promotes the survival of pulmonary arterial endothelial cells (PAECs), as well as the specific molecular mechanisms that underlie its actions, remains unknown. METHODS: MTT assays, caspase-3 and caspase-9 activity assays and western blot analysis were performed. RESULTS: We found that both the mRNA and protein expression of PDGF-B was induced by hypoxia and that the inhibitory effects exerted by hypoxia on apoptosis were attenuated by inhibitors of PDGF beta. Moreover, PDGF-B inhibited apoptosis in a dose-dependent manner by stimulating the phosphorylation of both Akt and Stat3, and the PI3K/AKT pathway serves as an up-stream participant in the Stat3 activation stimulated by PDGF-B. Additionally, the anti-apoptotic effects of PDGF-B were abolished when PAECs were treated with either an inhibitor or small interfering RNA targeting Stat3. CONCLUSIONS: These observations suggest that PDGF-B is induced by hypoxia and protects against apoptosis via the PI3K/Akt/Stat3 signaling pathway.

Long-term efficacy and safety of arsenic trioxide for first-line treatment of elderly patients with newly diagnosed acute promyelocytic leukemia.

BACKGROUND: The prognosis of acute promyelocytic leukemia (APL) in the elderly is poorer than that of younger patients after treatment with all-trans retinoic acid plus chemotherapy, which is the current standard therapy for APL. A significantly higher mortality during consolidation therapy was found, which is mainly due to deaths from sepsis following chemotherapy-induced myelosuppression. METHODS: A total of 33 patients aged 60 years or older with de novo APL were treated with single-agent arsenic trioxide (ATO) for remission induction and postremission therapy. The postremission therapy continued for up to 4 years. RESULTS: Twenty-nine patients (87.9%) achieved a hematologic complete remission, and the most common adverse event during remission induction was leukocytosis (63.6%). Definite differentiation syndrome was observed in 5 patients. Nonhematologic adverse events were all manageable and reversible. Twenty-eight patients proceeded to postremission therapy. Adverse effects during postremission therapy were mild, transient, and no treatment was required. No patients died from ATO-related toxicities. With a median follow-up of 99 months, the 10-year cumulative incidence of relapse, overall survival, disease-free survival, and cause-specific survival were 10.3%, 69.3%, 64.8%, and 84.8%, respectively, which are comparable with those in the younger APL partners. No significant risks for development of chronic arsenicosis or second malignancy were observed during the follow-up period. CONCLUSIONS: The results indicate that the single-agent ATO regimen is safe and effective with long-term durable remission, and could be used as first-line treatment for elderly patients with de novo APL.

Single-agent arsenic trioxide in the treatment of children with newly diagnosed acute promyelocytic leukemia.

The aim of this study was to determine the efficacy and safety of treatment of pediatric acute promyelocytic leukemia (APL) with single-agent arsenic trioxide (ATO). A total of 19 children (< or = 15 years of age) with newly diagnosed APL were treated with single-agent ATO for remission induction and postremission therapy. Seventeen of the children (89.5%) achieved complete hematologic remission, and 2 early deaths occurred from intracranial hemorrhage. ATO-induced leukocytosis was observed in 13 (68.4%) patients. Other ATO-related toxicities were minimal and transient. Postremission ATO therapy continued for 3 years; the most common side effect was ATO-induced neutropenia. With a median follow-up of 53 months (range, 23-76 months), the calculated 5-year overall survival and event-free survival were 83.9% and 72.7%, respectively, which are comparable with results achieved by the use of ATRA plus chemotherapy, which is the standard therapy for APL. No chronic arsenic toxicity or second malignancies were found during the follow-up period, and arsenic retention was not significant in patients off treatment more than 24 months. ATO resistance was observed in only 1 patient with a complex karyotype. The results indicate the high efficacy and safety of single-agent ATO regimens in the treatment of children with de novo APL.

miR-139-5p Regulates the Proliferation of Acute Promyelocytic Leukemia Cells by Targeting MNT.

Acute promyelocytic leukemia (APL) patients with progressive leukocytosis are more likely to have various complications and poor outcomes. However, the regulatory roles of microRNAs in the leukocytosis of APL have not been clarified. Our study aims to evaluate the effects of miRNAs on leukocytosis during induction therapy of APL patients and explore its potential mechanisms. During induction treatment, patients with white blood cell count higher than 10 × 109/L were divided into leukocytosis group and others were nonleukocytosis group. Using microarray assays, we found that miR-139-5p was significantly downregulated in the leukocytosis group. Elevated expression of miR-139-5p inhibited the proliferation of NB4 cells by arresting the cell cycle and inducing apoptosis. We further identified that MNT was a target of miR-139-5p. miR-139-5p significantly inhibited the proliferation, invasion, and migration function of NB4 cells through targeting MNT. Strategies for regulating miR-139-5p or MNT expression might provide new therapeutic approaches for progressive leukocytosis in APL.

Treatment response, survival, safety, and predictive factors to chimeric antigen receptor T cell therapy in Chinese relapsed or refractory B cell acute lymphoblast leukemia patients.

This study aimed to evaluate treatment response, survival, safety profiles, and predictive factors to chimeric antigen receptor T cell (CAR-T) therapy in Chinese patients with relapsed or refractory B cell acute lymphoblast leukemia (R/R B-ALL). 39R/R B-ALL patients who underwent CAR-T therapy were included. Baseline data were collected from patients' electronic medical records. Patients' peripheral bloods, bone marrow aspirates, and biopsies were obtained for routine examination, and treatment response and survival profiles as well as adverse events were evaluated. The rates of complete remission (CR), CR with minimal residual disease (MRD) negative/positive, and bridging to hematopoietic stem-cell transplantation (HSCT) were 92.3%, 76.9%, 15.4%, and 43.6%, respectively. The median event-free survival (EFS) was 11.6 months (95% confidence interval (CI): 4.0-19.2 months) and median overall survival (OS) was 14.0 months (95% CI: 10.9-17.1 months). Bridging to HSCT independently predicted better EFS and OS, while high bone marrow blasts level independently predicted worse EFS. The incidence of cytokine release syndrome (CRS) was 97.4%, and refractory disease as well as decreased white blood cell independently predicted higher risk of severe CRS. Other common adverse events included hematologic toxicities (grade I: 5.1%, grade II: 7.7%, grade III: 17.9%, grade IV: 69.2%), neurotoxicity (28.2%), infection (38.5%), and admission for intensive care unit (10.3%). In conclusion, CAR-T therapy presents with promising treatment response, survival and safety profiles, and higher disease burden predicts worse survival as well as increased risk of severe CRS in Chinese R/R B-ALL patients.

Methylation status of the promoter region of the human frizzled 9 gene in acute myeloid leukemia.

The FZD9 gene is located at chromosome 7q11.23, and has been indicated to be a tumor suppressor gene. The present study examined the involvement of FZD9 promoter methylation in the downregulation of FZD9 expression in leukemia cells. The expression of the FZD9 gene was absent in various leukemic cell lines, while it was restored following treatment with DNA demethylating agent 5­aza­2'­deoxycytidine. Bisulfite sequencing analysis of the FZD9 promoter region showed that it was partially methylated in cell lines in which FZD9 gene was not expressed. Thus, DNA methylation in the promoter region may lead to inactivation of the FZD9 gene, which may represent and aberration associated with leukemia, since DNA was not methylated in normal peripheral blood mononuclear cells. Methylation­specific polymerase chain reaction analysis revealed that the promoter region of the FZD9 gene was frequently methylated in primary or relapse acute myeloid leukemia (52.9%; excluding acute promyelocytic leukemia); however, methylation was infrequent in B­cell acute lymphocytic leukemia (5.6%). In conclusion, the present study indicated that the methylation profile of the FZD9 gene corresponded to that of a candidate tumor­suppressor gene in acute myeloid leukemia.

TGF-ß1 inhibits the apoptosis of pulmonary arterial smooth muscle cells and contributes to pulmonary vascular medial thickening via the PI3K/Akt pathway.

Previous studies have highlighted that the transforming growth factor­ß1 (TGF­ß1) pathway may be activated by hypoxic conditions. TGF­ß1 also participates in the regulation of proliferation, differentiation, migration and apoptosis of various cell types. Furthermore, TGF­ß1 has been reported to participate in the regulation of the progression of pulmonary arterial hypertension (PAH). However, the effect of TGF­ß1 on pulmonary arterial smooth muscle cells (PASMCs) and the corresponding molecular mechanisms remain unclear. The present study aimed to determine whether TGF­ß1 protects against cell apoptosis in PASMCs, and identify the underlying molecular mechanisms. Western blotting, MTT and lactate dehydrogenase activity assays were performed, and the activity of caspase­3 and caspase­9 was detected in order to investigate the hypothesis. It was determined that TGF­ß1 may facilitate cell growth in a dose­dependent manner in serum­starved PASMCs. Furthermore, it was observed that apoptosis in serum­starved PASMCs was inhibited by TGF­ß1 via regulation of the expression levels of mitochondrial membrane proteins. Additionally, the phosphatidylinositol 3­kinase/protein kinase B (PI3K/Akt) pathway was found to be activated by TGF­ß1 in PASMCs, while the inhibition of PI3K/Akt signaling also prevented the apoptosis­limiting effects of TGF­ß1. These observations suggest that TGF­ß1 protects PASMCs from apoptosis and contributes to pulmonary vascular medial thickening via the PI3K/Akt pathway.

Arsenic trioxide-based therapy is suitable for patients with psoriasis-associated acute promyelocytic leukemia - A retrospective clinical study.

OBJECTIVE: Many patients with psoriasis have developed acute promyelocytic leukemia (APL) whereas few reports on psoriasis-associated APL were found in the published literature. This study was aimed to study the etiology, clinical characteristics, and prognosis of psoriasis-associated APL and to map a suitable treatment regime for this condition. METHODS: This study retrospectively analyzed the clinical data of 17 patients with psoriasis-associated APL diagnosed and treated in our hospital in the past decade. RESULTS: The 17 patients accounted for 8.3% of the total patients diagnosed with de novo APL during the same period in our hospital. Their clinical characteristics of APL were similar to those of general APL. Four patients had a definite history of taking bimolane. All patients received arsenic trioxide (ATO)-based remission induction and postremission treatment. After induction, 15 patients (88%) achieved hematologic complete remission. With a median follow-up of 27 months, the 3-year estimates of overall survival were 77.2% ± 12.4% and the 3-year estimates of event-free survival were 70.6% ± 13.5%. In addition, the ATO-based remission induction and postremission treatment significantly improved psoriasis symptoms in 83 and 85.7% of patients, respectively. Through the final follow-up, no chronic arsenicosis or secondary malignancy was observed. CONCLUSIONS: Psoriasis patients are at high risk for APL. The increased risk is most likely associated with the genetic background and bimolane treatment. The ATO-based therapy is especially suitable for patients with psoriasis-associated APL. Our study also brings a new treatment option for psoriasis.