Xiaoyu Lai

T-cell-replete haploidentical HSCT with low-dose anti-T-lymphocyte globulin compared with matched sibling HSCT and unrelated HSCT

We developed an approach of T-cell-replete haploidentical hematopoietic stem cell transplantation (HSCT) with low-dose anti-T-lymphocyte globulin and prospectively compared outcomes of all contemporaneous T-cell-replete HSCT performed at our center using matched sibling donors (MSDs), unrelated donors (URDs), and haploidentical related donors (HRDs). From 2008 to 2013, 90 patients underwent MSD-HSCT, 116 underwent URD-HSCT, and 99 underwent HRD-HSCT. HRDs were associated with higher incidences of grades 2 to 4 (42.4%) and severe acute graft-versus-host disease (17.2%) and nonrelapse mortality (30.5%), compared with MSDs (15.6%, 5.6%, and 4.7%, respectively; P < .05), but were similar to URDs, even fully 10/10 HLA-matched URDs. For high-risk patients, a superior graft-versus-leukemia effect was observed in HRD-HSCT, with 5-year relapse rates of 15.4% in HRD-HSCT, 28.2% in URD-HSCT (P = .07), and 49.9% in MSD-HSCT (P = .002). Furthermore, 5-year disease-free survival rates were not significantly different for patients undergoing transplantation using 3 types of donors, with 63.6%, 58.4%, and 58.3% for MSD, URD, and HRD transplantation, respectively (P = .574). Our data indicate that outcomes after HSCT from suitably matched URDs and HRDs with low-dose anti-T-lymphocyte globulin are similar and that HRD improves outcomes of patients with high-risk leukemia. This trial was registered at www.chictr.org (Chinese Clinical Trial Registry) as #ChiCTR-OCH-12002490.

Hypoxia-Inducible Factor-1α Is Essential for Hypoxia-Induced Mesenchymal Stem Cell Mobilization into the Peripheral Blood

Mobilization of mesenchymal stem cells (MSCs) is a promising strategy for tissue repair and regenerative medicine. The establishment of an appropriate animal model and clarification of the underlying mechanisms are beneficial to develop the mobilization regimens for therapeutic use. In this study, we therefore established a rat MSC mobilization model and investigated the related mechanisms, using continuous hypoxia as the mobilizing stimulus. We found that MSCs could be mobilized into peripheral blood of rats exposed to short-term hypoxia (2 days) and the mobilization efficiency increased in a time-dependent manner (2-14 days). Hypoxia-inducible factor-1α (HIF-1α) was upregulated during hypoxic exposure and was expressed continuously in bone marrow. Inhibition of HIF-1α expression by YC-1 remarkably reduced the number of mobilized MSCs, suggesting that HIF-1α is essential for hypoxia-induced MSC mobilization. Further, we investigated the potential role of HIF-1α target genes, vascular endothelial growth factor (VEGF), and stromal cell-derived factor-1α (SDF-1α). VEGF expression was elevated from day 2 to day 7 of hypoxia, stimulating an increase in bone marrow sinusoidal vessels and possibly facilitating the egress of MSCs. SDF-1α protein levels were increased in the peripheral blood of rats during MSC mobilization and promoted the migration of MSCs under hypoxic conditions in vitro. These results suggest that HIF-1α plays a pivotal role in hypoxia-induced MSC mobilization, possibly acting via its downstream genes VEGF and SDF-1α. These data provide a novel insight into the mechanisms responsible for MSC mobilization and may help in the development of clinically useful therapeutic agents.

Cell cycle dependent telomere regulation by telomerase in human bone marrow mesenchymal stem cells

Human bone marrow mesenchymal stem cells (hMSCs) are a promising source for clinical stem cell transplantation. However, telomere regulation mechanisms, as one of the possible major mechanisms by which hMSCs sustain their stem cell characteristics, remain unknown. We isolated hMSCs by plastic adhesion and characterized these cells by morphology, immune phenotype and differentiation capacity. Telomerase was found negative in hMSCs, but slightly up-regulated in hMSC-derived adipocytes by the Telomeric Repeat Amplification Protocol (TRAP) assay. Moreover, hMSCs lack the alternative lengthening of telomeres (ALT) mechanism, because the hallmarks of ALT, such as very long and heterogeneous telomeres, extra-chromosome telomere repeat DNA (ECTR), and ALT-associated promyelocytic leukemia bodies (APBs), were not evident. However, when hMSCs were arrested in S phase with a combination of serum deprivation and aphidicolin, previously undetectable telomerase activity became predominantly positive. Meanwhile, the expression level of hTERT protein and mRNA increased, paralleled with the appearance of a large cohort of synchronized hMSCs at S phase. These findings provide a profile of telomere regulation by cell cycle dependent expression of telomerase in hMSCs and may lead to a better understanding of the stem cell nature of these cells.

Reduced-intensity allogeneic transplantation combined with imatinib mesylate for chronic myeloid leukemia in first chronic phase

Reduced-intensity allogeneic transplantation combined with imatinib mesylate for chronic myeloid leukemia in first chronic phase

The E3 ubiquitin ligase HECTD3 regulates ubiquitination and degradation of Tara

Tara was identified as an interacting partner of guanine nucleotide exchange factor Trio and TRF1. Tara is proposed to be involved in many important fundamental cellular processes, ranging from actin remodeling, directed cell movement, to cell cycle regulation. Yet, its exact roles required further elucidation. Here, we identify a novel Tara-binding protein HECTD3, a putative member of HECT E3 ubiquitin ligases. HECTD3 directly binds Tara in vitro and forms a complex with Tara in vivo. Overexpression of HECTD3 enhances the ubiquitination of Tara in vivo and promotes the turnover of Tara, whereas depletion of HECTD3 by small interfering RNA decreases Tara degradation. Furthermore, depletion of HECTD3 leads to multipolar spindle formation. All these findings suggest that HECTD3 may facilitate cell cycle progression via regulating ubiquitination and degradation of Tara.

Efficacy and prognosis of chronic myeloid leukemia treated with imatinib mesylate in a Chinese population

There is limited data from developing countries on the current status of imatinib treatment for chronic myeloid leukemia (CML), thus we retrospectively analyzed 116 Chinese CML patients who received imatinib between 2003 and 2008. The response rates for 102 patients in chronic phase were: complete hematologic, 94.1%; complete cytogenetic, 69.6%; and complete molecular response, 54.9%. For 14 patients in the accelerated phase, the respective response rates were 85.7, 35.7 and 28.6%. The 3-year progression-free survival and 5-year overall survival were 73.3 and 74.8%. Although skin hypopigmentation occurs as the most common side effect (77.6%), imatinib is still well tolerated. In addition to the known pretreatment characteristics of spleen size, leukocyte and platelet counts, disease phase and Sokal scores, we found that delayed therapy, variant Philadelphia chromosome translocations and IM-related grade 3/4 leucopenia were associated with an inferior cytogenetic response. Four factors emerged as predictors of disease progression: molecular response, cytogenetic response, disease phase and disease duration prior to imatinib treatment, but only the latter three remained significant after multivariate analysis. The results indicate that the suboptimal outcome in Chinese patients is associated with delayed imatinib therapy, so the importance of the optimal treatment opportunity for CML should be emphasized.

Antiproliferative effect of rapamycin on human T-cell leukemia cell line Jurkat by cell cycle arrest and telomerase inhibition

AbstractAim:To examine the ability of rapamycin to suppress growth and regulate telomerase activity in the human T-cell leukemia cell line Jurkat.Methods:Cell proliferation was assessed after exposure to rapamycin by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. Cell cycle progression and apoptosis were determined by flow cytometry. The proteins important for cell cycle progression and Akt/mammalian target of rapamycin signaling cascade were assessed by Western blotting. Telomerase activity was quantified by telomeric repeat amplication protocol assay. The human telomerase reverse transcriptase (hTERT) mRNA levels were determined by semi-quantitative RT-PCR.Results:Rapamycin inhibited the proliferation of Jurkat, induced G1 phase arrest, unregulated the protein level of p21 as well as p27, and downregulated cyclinD3, phospho-p70s6k, and phospho-s6, but had no effect on apoptosis. Treatment with rapamycin reduced telomerase activity, and reduced hTERT mRNA and protein expression.Conclusion:Rapamycin displayed a potent antileukemic effect in the human T-cell leukemia cell line by inhibition of cell proliferation through G1 cell cycle arrest and also through the suppression of telomerase activity, suggesting that rapamycin may have potential clinical implications in the treatment of some leukemias.

Association between DNMT3A Mutations and Prognosis of Adults with De Novo Acute Myeloid Leukemia: A Systematic Review and Meta-Analysis

Background DNA methyltransferase 3A (DNMT3A) mutations were considered to be independently associated with unfavorable prognosis in adults with de novo acute myeloid leukemia (AML), however, there are still debates on this topic. Here, we aim to further investigate the association between DNMT3A mutations and prognosis of patients with AML. Methods Eligible studies were identified from several data bases including PubMed, Embase, Web of Science, ClinicalTrials and the Cochrane Library (up to June 2013). The primary endpoint was overall survival (OS), while relapse-free survival (RFS) and event-free survival (EFS) were chosen as secondary endpoints. If possible, we would pool estimate effects (hazard ratio [HR] with 95% confidence interval[CI]) of outcomes in random and fixed effects models respectively. Results That twelve cohort studies with 6377 patients exploring the potential significance of DNMT3A mutations on prognosis were included. Patients with DNMT3A mutations had slightly shorter OS (HR = 1.60; 95% CI, 1.31–1.95; P<0.001), as compared to wild-type carriers. Among the patients younger than 60 years of age, DNMT3A mutations predicted a worse OS (HR = 1.84; 95% CI, 1.36–2.50; P<0.001). In addition, mutant DNMT3A predicted inferior OS (HR = 2.30; 95% CI, 1.78–2.97; P = 0.862) in patients with unfavorable genotype abnormalities. Similar results were also found in some other subgroups. However, no significant prognostic value was found on OS (HR = 1.40; 95% CI, 0.98–1.99; P = 0.798) in the favorable genotype subgroup. Similar results were found on RFS and EFS under different conditions. Conclusions DNMT3A mutations have slightly but significantly poor prognostic impact on OS, RFS and EFS of adults with de novo AML in total population and some specific subgroups.

PML3 interacts with TRF1 and is essential for ALT-associated PML bodies assembly in U2OS cells.

Telomerase-negative cancer cells maintain their telomeres by a mechanism known as alternative lengthening of telomeres (ALT) and achieve unlimited replicative potential. A hallmark of ALT cells is the recruitment of telomeres to promyelocytic leukemia (PML) bodies and formation of ALT-associated PML bodies (APBs). Although the exact molecular mechanism of APBs assembly remains unclear, APBs assembly requires telomere and PML body-associated proteins, including TRF1 and PML. Here, we report that PML3, one of PML isoforms, is involved in APBs formation. As a new binding protein of TRF1 (telomeric repeat binding factor 1), PML3 directly interacts with TRF1 and recruits TRF1 to PML bodies in U2OS cells. More notably, depletion of PML3 by small interfering RNA does not affect PML bodies formation, but inhibits the recruitment of both TRF1 and TRF2 to APBs. Further study shows that the recruitment of TRF1 to APBs depends on its interaction with a specific PML3 isoform. Thus, the interaction of PML3 with TRF1 is isoform specific and likely to be essential for APBs assembly in U2OS cells.

Distribution of killer-cell immunoglobulin-like receptor genes in Eastern mainland Chinese Han and Taiwanese Han populations.

The interaction between killer-cell immunoglobulin-like receptors (KIRs) and human leukocyte antigen (HLA) molecules expressed on target cells is known to modulate the cytolytic activity of natural killer (NK) cells. To date, a wide range of KIR genotypes has been observed, which varies among different ethnic populations. We report here comparison of the KIR gene content and genotypic structure of KIRs in 106 individuals from Eastern mainland Chinese Han and 97 from Taiwanese Han. All 17 KIR genes were observed in the two populations. Framework genes 2DL4, 3DL2, 3DL3 and 3DP1 were present in all individuals. The two populations had very similar frequencies in most loci, however, significant differences were noted in the frequencies of KIR3DS1 and KIR2DS4D (KIR2DS4 deletant variant). A total of 35 and 29 genotypes were identified in the individuals from the Eastern mainland Chinese and the Taiwanese Hans, respectively. Some pairs of KIRs showed significant positive and negative linkage disequilibrium (LD). Our data showed that there were minor distinctions in KIR gene frequencies, genotypes and LD between the two populations, which shed light on a possible geographic genetic demarcation among different Chinese communities.