Comparison of long-term outcomes between imatinib and dasatinib prophylaxis after allogeneic stem cell transplantation in patients with Philadelphia-positive acute lymphoblastic leukemia: A multicenter retrospective study

BACKGROUND

Although the prognosis of Philadelphia-positive acute lymphoblastic leukemia (Ph+ ALL) has improved with the introduction of tyrosine kinase inhibitors (TKIs) and stem cell transplantation, prevention of relapse after transplantation remains a concern. The aim of this study was to compare the impact of TKI prophylaxis with imatinib and dasatinib on long-term outcomes after transplantation.

METHODS

Patients with Ph+ ALL who underwent allogeneic hematopoietic stem cell transplantation (allo-HSCT) at first complete remission (CR1) and received TKI prophylaxis after allo-HSCT were included in this retrospective analysis. Two cohorts were established based on the choice of TKI prophylaxis: the imatinib (Ima) and dasatinib (Das) cohorts. The survival and safety outcomes of these cohorts were compared.

RESULTS

Ninety-one patients in the Ima cohort and 50 in the Das cohort were included. After a median follow-up of 50.6 months, the 5-year cumulative incidence of relapse, nonrelapse mortality rate, and overall survival in the Ima and Das cohorts were 16.1% and 12.5%, 5.2% and 9.8%, and 86.5% and 77.6%, respectively, with no statistical differences. The cumulative incidence of mild chronic graft-versus-host disease was higher in the Das cohort. The most common adverse event was neutropenia (64.7% vs. 69.5%). The Das cohort had a higher incidence of gastrointestinal bleeding (25.5% vs. 2.3%) and gastrointestinal reaction (48.9% vs. 31.4%) than the Ima cohort. The proportion of patients treated on schedule was significantly lower in the Das cohort than in the Ima cohort, and drug intolerance was the main reason for protocol violation.

CONCLUSIONS

For patients with Ph+ ALL undergoing allo-HSCT in CR1, imatinib prophylaxis achieved long-term outcomes similar to those of dasatinib.

[Efficacy and prognostic factors of allogeneic hematopoietic stem cell transplantation in the treatment of secondary acute myeloid leukemia]

Objective: To evaluate the efficacy and prognostic factors of allogeneic hematopoietic stem cell transplantation (allo-HSCT) in patients with secondary acute myeloid leukemia (sAML) . Methods: In this multicenter, retrospective clinical study, adult patients aged ≥18 years who underwent allo-HSCT for sAML at four centers of the Zhejiang Hematopoietic Stem Cell Transplantation Collaborative Group from January 2014 to November 2022 were included, and the efficacy and prognostic factors of allo-HSCT were analyzed. Results: A total of 95 patients were enrolled; 66 (69.5%) had myelodysplastic syndrome-acute myeloid leukemia (MDS-AML) , 4 (4.2%) had MDS/MPN-AML, and 25 (26.3%) had therapy-related AML (tAML) . The 3-year CIR, LFS, and overall survival (OS) rates were 18.6% (95% CI 10.2%-27.0%) , 70.6% (95% CI 60.8%-80.4%) , and 73.3% (95% CI 63.9%-82.7%) , respectively. The 3-year CIRs of the M-AML group (including MDS-AML and MDS/MPN-AML) and the tAML group were 20.0% and 16.4%, respectively (P=0.430) . The 3-year LFSs were 68.3% and 75.4%, respectively (P=0.176) . The 3-year OS rates were 69.7% and 75.4%, respectively (P=0.233) . The 3-year CIRs of the groups with and without TP53 mutations were 60.0% and 13.7%, respectively (P=0.003) ; the 3-year LFSs were 20.0% and 76.5%, respectively (P=0.002) ; and the 3-year OS rates were 40.0% and 77.6%, respectively (P=0.002) . According to European LeukmiaNet 2022 (ELN2022) risk stratification, the 3-year CIRs of patients in the low-, intermediate-, and high-risk groups were 8.3%, 17.8%, and 22.6%, respectively (P=0.639) . The three-year LFSs were 91.7%, 69.5%, and 65.6%, respectively (P=0.268) . The 3-year OS rates were 91.7%, 71.4%, and 70.1%, respectively (P=0.314) . Multivariate analysis revealed that advanced disease at allo-HSCT and TP53 mutations were independent risk factors for CIR, LFS, and OS. Conclusion: There was no significant difference in the prognosis of patients who underwent allo-HSCT among the MDS-AML, MDS/MPN-AML, and tAML groups. Advanced disease at transplantation and TP53 mutations were poor prognostic factors. ELN2022 risk stratification had limited value for predicting the prognosis of patients with sAML following allo-HSCT.

Dysbiosis and primary B-cell immunodeficiencies: current knowledge and future perspective

According to Elie Metchnikoff, an originator of modern immunology, several pivotal functions for disease and health are provided by indigenous microbiota. Nonetheless, important mechanistic insights have been elucidated more recently, owing to the growing availability of DNA sequencing technology. There are 10 to 100 trillion symbiotic microbes (such as viruses, bacteria, and yeast) in each human gut microbiota. Both locally and systemically, the gut microbiota has been demonstrated to impact immune homeostasis. Primary B-cell immunodeficiencies (PBIDs) are a group of primary immunodeficiency diseases (PIDs) referring to the dysregulated antibody production due to either intrinsic genetic defects or failures in functions of B cells. Recent studies have found that PBIDs cause disruptions in the gut's typical homeostatic systems, resulting in inadequate immune surveillance in the gastrointestinal (GI) tract, which is linked to increased dysbiosis, which is characterized by a disruption in the microbial homeostasis. This study aimed to review the published articles in this field to provide a comprehensive view of the existing knowledge about the crosstalk between the gut microbiome and PBID, the factors shaping the gut microbiota in PBID, as well as the potential clinical approaches for restoring a normal microbial community.

A Novel Prognostic Scoring Model for Myelodysplastic Syndrome Patients With SF3B1 Mutation

The outcomes of myelodysplastic syndrome (MDS) patients with SF3B1 mutation, despite identified as a favorable prognostic biomarker, are variable. To comprehend the heterogeneity in clinical characteristics and outcomes, we reviewed 140 MDS patients with SF3B1 mutation in Zhejiang province of China. Seventy-three (52.1%) patients diagnosed as MDS with ring sideroblasts (MDS-RS) following the 2016 World Health Organization (WHO) classification and 118 (84.3%) patients belonged to lower risk following the revised International Prognostic Scoring System (IPSS-R). Although clonal hematopoiesis-associated mutations containing TET2, ASXL1 and DNMT3A were the most frequent co-mutant genes in these patients, RUNX1, EZH2, NF1 and KRAS/NRAS mutations had significant effects on overall survival (OS). Based on that we developed a risk scoring model as IPSS-R×0.4+RUNX1×1.1+EZH2×0.6+RAS×0.9+NF1×1.6. Patients were categorized into two subgroups: low-risk (L-R, score <= 1.4) group and high risk (H-R, score > 1.4) group. The 3-year OS for the L-R and H-R groups was 91.88% (95% CI, 83.27%-100%) and 38.14% (95% CI, 24.08%-60.40%), respectively (P<0.001). This proposed model distinctly outperformed the widely used IPSS-R. In summary, we constructed and validated a personalized prediction model of MDS patients with SF3B1 mutation that can better predict the survival of these patients.

Safety and efficacy of a humanized CD19 chimeric antigen receptor T cells for relapsed/refractory acute lymphoblastic leukemia

CD19-targeted chimeric antigen receptor T (CAR-T) cells using murine single-chain variable fragment (scFv) has shown substantial clinical efficacy in treating relapsed/refractory acute lymphoblastic leukemia (R/R ALL). However, potential immunogenicity of the murine scFv domain may limit the persistence of CAR-T cells. In this study, we treated 52 consecutive subjects with R/R ALL with humanized CD19-specific CAR-T cells (hCART19s). Forty-six subjects achieved complete remission (CR) (N = 43) or CR with incomplete count recovery (CRi) (N = 3) within 1 month post infusion. During the follow-up with a median time of 20 months, the 1-year cumulative incidence of relapse was 25% (95% confidence interval [CI] 13-46), and 1-year event-free survival was 45% (95% CI 29-60). To the cutoff date, 20 patients presented CD19⁺ relapse and 2 had CD19^- relapse. Among the 22 relapsed patients, 14 had treatment-mediated and treatment-boosted antidrug antibodies (ADA) as detected in a sensitive and specific cell-based assay. ADA positivity was correlated with the disease relapse risk. ADA-positive patients had a significantly lower CAR copy number than ADA-negative patients at the time of recurrence (p < .001). In conclusion, hCART19s therapy is safe and highly active in R/R ALL patients, and the hCART19s treatment could induce the emergence of ADA, which is related to the recurrence of the primary disease.

Arsenic trioxide induces proteasome dependent TBLR1-RARα degradation to improve leukemia eradication through cell differentiation enhancement

Background: Acute promyelocytic leukemia (APL) mainly harbors PML-RARα fusion gene, which is sensitive to all-trans retinoic acid (ATRA) and arsenic trioxide (ATO) treatment. However, APL harboring other RARα fusion genes exhibit different drug sensitivity. Here, we investigated the role and mechanism of TBLR1-RARα, a rare RARα fusion gene, on ATO treatment in leukemia cells.

Methods: By constructing two cell models of leukemia cell line HL-60 and U937 with overexpressed TBLR1-RARα, we detected the cell differentiation in the two cell models after ATO treatment by flow cytometry and Wright staining. Meanwhile, cell viability, colony formation and apoptosis were also determined after ATO treatment.

Results: We found that TBLR1-RARα enhanced ATO-induced apoptosis and cell proliferation inhibition. Besides, TBLR1-RARα also promoted ATO-induced cell differentiation. Furthermore, we found that the mitochondrial caspase pathway was involved in the apoptosis induced by ATO treatment in TBLR1-RARα positive leukemia cells. Moreover, ATO mediated TBLR1-RARα protein degradation via proteasome pathway, which accounts for the transcriptional activation of RARα target gene and is further involved in cell differentiation of TBLR1-RARα positive leukemia cells.

Conclusions: Our study provides evidence that TBLR1-RARα positive APL patients may benefit from ATO treatment, thereby improving the appropriate management in TBLR1-RARα positive APL.

Acute Mast Cell Leukemia Preceded by Malignant Mediastinal Germ Cell Tumor: A Case Report and Literature Review

Background

Case Presentation

Conclusion

Long-Term Follow-Up of Combination of B-Cell Maturation Antigen and CD19 Chimeric Antigen Receptor T Cells in Multiple Myeloma

PURPOSE

A combination of anti-B-cell maturation antigen (BCMA) and anti-CD19 chimeric antigen receptor (CAR) T cells induced high response rates in patients with relapsed or refractory (R/R) multiple myeloma (MM), but long-term outcomes have not been assessed yet.

PATIENTS AND METHODS

In this single-arm, phase II trial, patients with R/R MM received a combination of anti-BCMA CAR T cells and anti-CD19 CAR T cells at a dose of 1 × 10⁶ cells/kg, after receiving a conditioning chemotherapy consisting of cyclophosphamide and fludarabine. The overall response, long-term outcomes, and safety were assessed, as were their associations with clinical and disease characteristics.

RESULTS

Of 69 enrolled patients, 62 received the combined infusion of anti-BCMA and anti-CD19 CAR T cells with a median follow-up of 21.3 months. The overall response rate was 92% (57/62), and complete response or better was observed in 37 patients (60%). Minimal residual disease-negativity was confirmed in 77% (43/56) of the patients with available minimal residual disease detection. The estimated median duration of response was 20.3 months (95% CI, 9.1 to 31.5). The median progression-free survival was 18.3 months (95% CI, 9.9 to 26.7), and the median overall survival was not reached. Patients with extramedullary disease had significantly inferior survival. Fifty-nine patients (95%) had cytokine release syndrome, with 10% grade 3 or higher. Neurotoxic events occurred in seven patients (11%), including 3% grade 3 or higher. Late adverse effects were rare, except for B-cell aplasia, hypogammaglobulinemia, and infections.

CONCLUSION

The combination of anti-BCMA and anti-CD19 CAR T cells induced durable response in patients with R/R MM, with a median progression-free survival of 18.3 months and a manageable long-term safety profile.

[Analysing pathogenic bacterial spectrum and drug resistance of bloodstream infection in patients with allogeneic hematopoietic stem cell transplantation]

Objective: To elucidate the clinical characteristics of bloodstream infection in patients with allogeneic hematopoietic stem cell transplantation (allo-HSCT) in our hospital and improves the survival of transplant patients with bloodstream infection. Methods: Two hundred and ten patients with allo-HSCT from the Department of Hematology were retrospectively analyzed between October 2014 and September 2019. Pathogen distribution, drug resistance, risk factors, and outcomes were investigated in 49 allo-HSCT patients with bloodstream infections. Results: Forty-nine of 210 patients with allo-HSCT had bloodstream infection, and 59 pathogenic microorganisms were identified, mainly Gram-negative bacteria (67.8%) , of which E. coli had the highest incidence (23.7%) , CRO accounted for 42.5%, and Grampositive bacteria accounted for 23.7% (without vancomycin or linezolid-resistant strain) . Additionally, fungi accounted for 8.5%. Univariate analysis suggested that the risk factors of bloodstream infection were gender, pretransplant disease status, and conditioning regimen. In contrast, multivariate analysis showed that bloodstream infection was mainly related to conditioning regimens. Further grouping results showed that 77.6% of patients with neutropenia had bloodstream infections, and 22.4% of patients with non-neutropenia had bloodstream infections; 81.0% of patients with active infections before transplantation had bloodstream infections, while bloodstream infection occurred in 16.9% of patients without active infection. Survival analysis showed that long-term survival of patients with bloodstream infection is shorter than that of patients without bloodstream infection and long-term survival of patients with CRO infection is shorter than that of patients without CRO infection. The survival of patients with neutropenia longer than 14 d is shorter than that of patients with neutropenia shorter than 14 d. Furthermore, there is no correlation between whether there is an active infection before transplantation and whether they are in a neutropenic state at the time of infection and survival. Conclusion: Our results suggest that effective prevention of bloodstream infections from drug-resistant bacteria, particularly CRO, shortening the duration of neutropenia, eradication of potential infections before transplantation, and patient-adaptive conditioning could reduce transplant-related mortality and improve prognosis.

Bone marrow stromal cells derived exosomal miR-10a and miR-16 may be involved in progression of patients with multiple myeloma by regulating EPHA8 or IGF1R/CCND1

Interaction with bone marrow stromal cells (BMSCs) has been suggested as an important mechanism for the progression of multiple myeloma (MM) cells, while exosomes are crucial mediators for cell-to-cell communication. The study was to investigate the miRNA profile changes in exosomes released by BMSCs of MM patients and explore their possible function roles.The microarray datasets of exosomal miRNAs in BMSCs were downloaded from the Gene Expression Omnibus database (GSE110271: 6 MM patients, 2 healthy donors; GSE78865: 4 donors and 2 MM patients; GSE39571: 7 MM patients and 4 controls). The differentially expressed miRNAs (DEMs) were identified using the LIMMA method. The target genes of DEMs were predicted by the miRwalk 2.0 database and the hub genes were screened by constructing the protein-protein interaction (PPI) network, module analysis and overlapping with the differentially expressed genes (DEGs) after overexpression or knockout of miRNAs.Three downregulated DEMs were found to distinguish MM from normal and MM-MGUS controls in the GSE39571 dataset; one downregulated and one upregulated DEMs (hsa-miR-10a) could differentiate MM from normal and MM-MGUS controls in the GSE110271-GSE78865 merged dataset. Furthermore, 11 downregulated (hsa-miR-16) and 1 upregulated DEMs were shared between GSE39571 and merged dataset when comparing MM with normal samples. The target genes were predicted for these 17 DEMs. PPI with module analysis showed IGF1R and CCND1 were hub genes and regulated by hsa-miR-16. Furthermore, EPHA8 was identified as a DEG that was downregulated in MM cells when the use of has-miR-10a mimics; while IGF1R, CCND1, CUL3, and ELAVL1 were also screened as DEGs that were upregulated in MM cells when silencing of hsa-miR-16.BMSCs-derived exosomal miR-10a and miR-16 may be involved in MM progression by regulating EPHA8 or IGF1R/CCND1/CUL3/ELAVL1, respectively. These exosomal miRNAs or genes may represent potential biomarkers for diagnosis of MM and prediction of progression and targets for developing therapeutic drugs.

Ruxolitinib combined with etanercept induce a rapid response to corticosteroid-refractory severe acute graft vs host disease after allogeneic stem cell transplantation: Results of a multi-center prospective study

About half of patients with severe acute graft vs host disease (aGVHD) show resistance to treatment with first-line steroids. We enrolled 64 patients with grades III-IV SR-aGVHD after allogeneic hematopoietic stem cell transplantation (allo-SCT), to assess the efficacy and safety of the combination therapy of ruxolitinib and etanercept. The overall response rate was 87.5% (95% CI, 79.7%-95.3%) at day 28 of the combination treatment, from which 73.4% reached complete response (CR). A marked reduction ≥75% in daily corticosteroid dosing was documented in 75.4% of patients at day 28. Delayed time from aGVHD to ruxolitinib (OR = 4.88, 95% CI, 0.98-23.56), stages 3-4 liver aGVHD (OR = 8.57, 95% CI, 0.96-46.59) and gut Enterobacteriaceae colonization (OR = 12.39, 95% CI, 1.71-59.77) were related to incomplete response. Grades 3/4 anemia, leukopenia, or thrombocytopenia and CMV-reactivation were found in 29.7%, 26.6%, 39.1%, and 50.0% of patients, respectively. So, 25 (39.1%) experienced complications of severe infection ≥3 grade, in which pulmonary infections were most frequent (15/64, 23.4%). The 2-year overall survival (OS) after the combination therapy was 61.2%. The 2-year incidence of non-relapse mortality and relapse of the underlying malignancy was 26.7% and 15.7%, respectively. Combined treatment with ruxolitinib and etanercept was very effective and relatively safe for severe aGVHD patients, while the various infection complications deserve more attention. This study was registered at the Chinese Clinical Trial Registry (ChiCTR1900024408).

Echinocandins versus Amphotericin B Against Candida tropicalis Fungemia in Adult Hematological Patients with Neutropenia: A Multicenter Retrospective Cohort Study

Background

Candida tropicalis is the most common non-albicans Candida species identified in immunocompromised patients, which often appears with high mortality. However, data on the outcomes of treatment for Candida tropicalis fungemia in patients with neutropenia remain limited.

Methods

In the present study, 90 neutropenic adult patients with proven Candida tropicalis fungemia, who received initial antifungal therapy, were retrospectively analyzed.

Results

These results revealed that the overall 8-day and 30-day mortality among patients in the entire data set were 22.2% and 33.3%, respectively. However, there was no significant difference between the survival and death group, in terms of baseline characteristics. The univariate analysis of risk factors identified the treatment with azole as a predictor of mortality, while treatments that containing amphotericin B were associated with reduced mortality. In addition, the survival rate on day 30 was observed in 60.7% (17/28) of patients who were initially treated with echinocandins, while this was observed in 86.4% (19/22, P=0.039) and 100% (13/13, P=0.024) of patients treated with amphotericin B plus echinocandins and amphotericin B, respectively.

Conclusion

These data indicate for the first time that the initial therapy with amphotericin B-based agents was associated with a better survival rate and could be assessed as the optimal strategy for the treatment of Candida tropicalis fungemia in patients with neutropenia.

Epigenetic priming with decitabine followed by low dose idarubicin and cytarabine in acute myeloid leukemia evolving from myelodysplastic syndromes and higher-risk myelodysplastic syndromes: a prospective multicenter single-arm trial

Patients with acute myeloid leukemia (AML) evolving from myelodysplastic syndrome (MDS) or higher-risk MDS have limited treatment options and poor prognosis. Our previous single-center study of decitabine followed by low dose idarubicin and cytarabine (D-IA) in patients with myeloid neoplasms showed promising primary results. We therefore conducted a multicenter study of D-IA regimen in AML evolving from MDS and higher-risk MDS. Patients with AML evolving from MDS or refractory anemia with excess blasts type 2 (RAEB-2) (based on the 2008 WHO classification) were included. The D-IA regimen (decitabine, 20 mg/m² daily, days 1 to 3; idarubicin, 6 mg/m² daily, days 4 to 6; cytarabine 25 mg/m² every 12 hours, days 4 to 8; granulocyte colony stimulating factor [G-CSF], 5 μg/kg, from day 4 until neutrophil count increased to 1.0 × 10⁹ /L) was administered as induction chemotherapy. Seventy-one patients were enrolled and treated, among whom 44 (62.0%) had AML evolving from MDS and 27 (38.0%) had RAEB-2. Twenty-eight (63.6%) AML patients achieved complete remission (CR) or complete remission with incomplete blood count recovery (CRi): 14 (31.8%) patients had CR and 14 (31.8%) had CRi. Six (22.2%) MDS patients had CR and 15 (55.6%) had marrow complete remission. The median overall survival (OS) was 22.4 months for the entire group, with a median OS of 24.2 months for AML and 20.0 months for MDS subgroup. No early death occurred. In conclusion, the D-IA regimen was effective and well tolerated, representing an alternative option for patients with AML evolving from MDS or MDS subtype RAEB-2.

Langerhans cell sarcoma arising from antecedent langerhans cell histiocytosis: A case report

RATIONALE

Langerhans cell sarcoma (LCS) is a rare, high-grade neoplasm characterized by overtly malignant cytologic features and a poor prognosis. Herein, we present a rare case of langerhans cell histiocytosis (LCH) that later transformed into langerhans cell sarcoma 11 months after the benign mass was excised from soft tissue in the right groin.

PATIENT CONCERNS

A 41-year-old patient who presented with a mass in the right groin for 3 years earlier after being bitten by ants.

DIAGNOSES

The patient was diagnosed with langerhans cell sarcoma arising from antecedent langerhans cell histiocytosis.

INTERVENTIONS

The patient underwent with 6 cycles of a modified etoposide, cyclophosphamide, vindesine, dexamethasone (E-CHOP) regimen.

OUTCOMES

The patient is currently receiving follow-up care.

LESSONS

LCH transformed into LCS is a rare case. E-CHOP as an effective first-line therapy to treat LCS cases, but, the mechanism is unclear. Due to their rarity, further data on clinical outcomes are necessary to establish the optimal treatment strategy for LCS.

Long non-coding RNA SNHG16 has Tumor suppressing effect in acute lymphoblastic leukemia by inverse interaction on hsa-miR-124-3p

Acute lymphoblastic leukemia (ALL) is one of the deadly forms of childhood cancers in the world. In the present study, we used both in vitro and in vivo models to evaluate the functional mechanisms of a long noncoding RNA (lncRNA), small nucleolar RNA host gene 16 (SNHG16) in ALL. SNHG16 gene expression was evaluated by quantitative real-time PCR (qPCR) in both in vitro ALL cell lines and in vivo human samples of T lymphocytes. Lentivirus-mediated SNHG16 downregulation was performed in MOLT3 and SUP-B15 cells, to evaluate its functional effects on ALL cell proliferation, migration in vitro, and ALL transplant in vivo. Epigenetic regulation of SNHG16 on human miR-124-3p (hsa-miR-124-3p) was evaluated by dual-luciferase activity assay and qPCR. Hsa-miR-124-3p was inhibited in SNHG16-downregulated MOLT3 and SUP-B15 cells to further evaluate the functional correlation between SNHG16 and hsa-miR-124-3p in ALL. SNHG16 is upregulated in both in vitro ALL cell lines and in vivo human leukemic T-cells. SNHG16 downregulation suppressed ALL proliferation and migration in vitro, and ALL explant in vivo. Hsa-miR-124-3p was demonstrated to interact with SNHG16, and upregulated in SNHG16-downregulated ALL cells. In addition, inhibiting hsa-miR-124-3p reversed SNHG16-downregulation-mediated tumor suppressive functions in ALL. SNHG16 is upregulated in ALL, and its inhibition has tumor suppressive effect in ALL, likely through epigenetic interaction on hsa-miR-124-3p. © 2018 IUBMB Life, 71(1):134-142, 2019.

Incidence, Survival, and Risk Factors for Adults with Acute Myeloid Leukemia Not Otherwise Specified and Acute Myeloid Leukemia with Recurrent Genetic Abnormalities: Analysis of the Surveillance, Epidemiology, and End Results (SEER) Database, 2001-2013

BACKGROUND/AIM

As the knowledgebase of acute myeloid leukemia (AML) has grown, classification systems have moved to incorporate these new findings.

METHODS

We assessed 32,941 patients with AML whose records are contained in the Surveillance, Epidemiology, and End Results (SEER) database.

RESULTS

Half of all patients diagnosed between 2001 and 2013 did not have a World Health Organization (WHO) classification. Acute promyelocytic leukemia and acute panmyelosis with myelofibrosis were associated with the longest leukemia-specific survival (110 and 115 months, respectively), and AML with minimal differentiation and acute megakaryoblastic leukemia with the shortest (30 and 28 months, respectively). For patients in the WHO groups AML not otherwise specified (AML-NOS) and AML with recurrent genetic abnormalities (AML-RGA), the risk of death was greater for older patients and less for married patients. Black patients with any type of AML-NOS also had a higher risk of death. Patients whose case of AML did not receive a WHO classification were older and this group had a higher risk of death when compared to patients with a WHO type of AML-NOS.

CONCLUSION

Our findings highlight the divergent outcomes of patients with AML and the importance of using the WHO classification system and demographic factors to gauge their prognosis.

Combining therapeutic antibodies using basiliximab and etanercept for severe steroid-refractory acute graft-versus-host disease: A multi-center prospective study

Acute graft versus host disease (aGVHD) remains a major problem after allogeneic hematopoietic stem cell transplantation. Standard frontline therapy for aGVHD involves corticosteroids. However, fewer than half of patients have a lasting complete response. The long-term mortality rate of steroid-refractory aGVHD (SR-aGVHD) remains around 70%. To date, no consensus has been reached regarding the optimal salvage treatment for SR-aGVHD. We performed the first prospective, multi-center clinical trial to assess the efficacy and safety of a novel approach to treat severe (grades III-IV) SR-aGVHD with the combination of basiliximab and etanercept. Sixty-five patients with severe SR-aGVHD from six centers were included. The median number of basiliximab infusions was 4 (range 2-11) and of etanercept was 9 (range 2-12). At day 28 after starting the combination treatment, overall response (complete and partial response: CR+PR) to second-line treatment was 90.8% with 75.4% being CR. The incidences of CR per organ were 100%, 73.8%, and 79.7% for skin, liver, and gut involvement, respectively. Patients >30-y old (p = 0.043, RR = 3.169), development of grades III-IV liver aGVHD (p = 0.007, RR = 5.034) and cytomegalovirus (CMV) reactivation (p = 0.035, RR = 4.02) were independent predictors for incomplete response. Combined treatment with basiliximab and etanercept resulted in improved CR to visceral aGVHD and significantly superior 2-y overall survival (54.7% vs. 14.8%, p <0.001) compared with classical salvage treatments. Our data suggest that the combination of basiliximab and etanercept may constitute a promising new treatment option for SR-aGVHD.

Embelin sensitizes acute myeloid leukemia cells to TRAIL through XIAP inhibition and NF-κB inactivation

Tumor necrosis factor-related apoptosis-inducing ligand (TRAIL) shows promising result in cancer therapy and induces apoptosis in a wide variety of tumor cells, without causing toxicity to normal cells. However, many tumor cells including acute myeloid leukemia (AML) showed certain degrees of resistance to TRAIL and the mechanism remains largely unknown. Embelin is a potent XIAP inhibitor which has been shown to inhibit the proliferation of tumor cells and cause cell apoptosis. In this study, we investigated the effects of Embelin on the TRAIL-induced apoptosis and the underlying mechanism. Here, we chose an adenovirus vector as the expression vector for TRAIL, which was named Ad-TRAIL. The results in vitro showed that the co-treatment of Embelin and Ad-TRAIL has synergistically suppressed the proliferation of AML cells. Embelin has the ability to enhance TRAIL-induced apoptosis and activate caspase pathway. More interestingly, we found that the underlying mechanism for these talent skills of Embelin is through reducing the TRAIL-mediated activation of NF-κB and decreasing its transcriptional activity. Furthermore, our results in vivo suggest that combined therapy of Embelin and Ad-TRAIL caused significant growth inhibition of HL-60 xenograft tumors. Our results suggested that Embelin could sensitize AML cell to TRAIL through the repression of NF-κB signal pathway in vitro and in vivo, and combined therapy of Ad-TRAIL and Embelin may be the attractive candidate for clinical application in treatment of AML.

[Computed tomographic images analysis of frontal recess anatomy based on three-dimension reconstruction]

OBJECTIVE

To observe the CT three-dimensional imaging features of the frontal recess region with advanced three-dimensional reconstruction, and develop the real image of the important anatomical structures around the region to conduct surgery.

METHOD

Thirty patients were undergone spiral CT by 16 line high speed spiral CT, and multiplanar reconstruction images using standard three-dimensional reconstruction protocol on a computer workstation. The structure of the frontal recess, the agger nasi cell and adhere style of the uncinate process were observed. The parameter of the important anatomic structure of frontal recess was measured precisely.

RESULT

After the reconstruction, we get the three-dimensional model very close to the true state of the nasal cavity-sinuses cell, in which parts of the frontal recess can clearly identify the agger nasi cell, frontal cell and other important structures. In these patients, the height, width and depth of the agger nasi and frontal sinus were (9.45 ± 3.60)mm, (8.08 ± 3.37)mm, (26.98 ± 6.82)mm and (26.86 ± 9.45)mm, respectively.

CONCLUSION

This study tried to develop the standardized techniques and measurements from three-dimensional reconstructed images of the frontal sinus and to ascertain the usefulness of the frontal sinus in identification of patients. The project results in better preoperative patient counselling and in predicting postoperative improvement in clinical status.

The 68-kDa telomeric repeat binding factor 1 (TRF1)-associated protein (TAP68) interacts with and recruits TRF1 to the spindle pole during mitosis

The telomere capping protein TRF1 is a component of the multiprotein complex "shelterin," which organizes the telomere into a high order structure. Besides telomere maintenance, telomere-associated proteins also have nontelomeric functions. For example, tankyrase 1 and TRF1 are required for the maintenance of faithful mitotic progression. However, the functional relevance of their centrosomal localization has not been established. Here, we report the identification of a TRF1-binding protein, TAP68, that interacts with TRF1 in mitotic cells. TAP68 contains two coiled-coil domains and a structural maintenance of chromosome motifs and co-localizes with TRF1 to telomeres during interphase. Immediately after nuclear envelope breakdown, TAP68 translocates toward the spindle poles followed by TRF1. Dissociation of TAP68 from the telomere is concurrent with the Nek2A-dependent phosphorylation at Thr-221. Biochemical characterization demonstrated that the first coiled-coil domain of TAP68 binds and recruits TRF1 to the centrosome. Inhibition of TAP68 expression by siRNA blocked the localization of TRF1 and tankyrase 1 to the centrosome. Furthermore, siRNA-mediated depletion of TAP68 perturbed faithful chromosome segregation and genomic stability. These findings suggest that TAP68 functions in mediating TRF1-tankyrase 1 localization to the centrosome and in mitotic regulation.

[3D computed tomographic analysis of frontal recess region]

OBJECTIVE

The purpose of the study was to observe the three-dimensional (3D) CT imaging features of the frontal recess region with 3D reconstruction, and obtain the real image of the important anatomical structures of the region to conduct surgery.

METHOD

Five patients were undergone spiral CT by 16 line high speed spiral CT, and multiplanar reconstruction images using standard 3D reconstruction protocol on a computer workstation. The structure of the frontal recess, the agger nasi cell and adhere style of the uncinate process were observed. The parameter of the important anatomic structure of frontal recess was measured precisely.

RESULT

After the reconstruction, we get the 3D model very close to the true state of the nasal cavity--sinuses cell, in which parts of the frontal recess can clearly identify the agger nasi cell, frontal cell and other important structures. In this patient, the height, width and depth of the agger nasi and frontal sinus were 12.3 mm, 12.1 mm, 38.5 mm, respectively.

CONCLUSION

This study tried to develop the standardized techniques and measurements from 3D reconstructed images of the frontal sinus and to ascertain the usefulness of the frontal sinus in identification of patients. The results in better preoperative patient counselling and in predicting postoperative improvement in clinical status.

Phosphorylation of Tara by Plk1 is essential for faithful chromosome segregation in mitosis

Trio-associated repeat on actin (Tara) is an F-actin binding protein and regulates actin cytoskeletal organization. In our previous study, we have found that Tara associates with telomeric repeat binding factor 1 (TRF1) and mediates the function of TRF1 in mitotic regulation. We also found that overexpression HECTD3, a member of HECT E3 ubiquitin ligases, enhances the ubiquitination of Tara in vivo and promotes the degradation of Tara, and such degradation of Tara facilitates cell cycle progression. However, less is known about the post-translational modification of Tara in mitosis. Here we show that Tara is a novel Polo-like kinase 1 (Plk1) target protein. Plk1 interacts with and phosphorylates Tara in vivo and in vitro. Actually, the Thr-457 in Tara was a bona fide in vivo phosphorylation site for Plk1. Interestingly, we found that the centrosomal localization of Tara depended on the Thr-457 phosphorylation and the kinase activity of Plk1. Furthermore, overexpression of non-phosphorylatable mutant of Tara caused aberrant mitosis delay in HeLa cells. Our study demonstrated that Plk1-mediated phospho-dependent centrosomal localization of Tara is important for faithful chromosome segregation, and provided novel insights into understanding on the role of Plk1 in cooperation with Tara in mitotic progression.

Identification and expression analysis of components involved in rice Xa21-mediated disease resistance signalling

Rice Xa21 gene encodes a receptor-like kinase that confers broad-spectrum resistance against Xanthomonas oryzae pv. oryzae (Xoo). Recently, a number of genes involved in the Xa21-mediated disease resistance pathway have been identified. Based on our previous data and the literature, we chose 16 candidate proteins and made corresponding antibodies. Using Western blotting, we systematically investigated the expression profile of the proteins in Xa21-mediated disease resistance response. We found nine proteins with altered expression. We further compared their expression in resistance, susceptible and mock responses, and found that GST expression was up-regulated during the resistance process, indicating GST is a positive regulator in resistance responses. ATPsB expression was down-regulated during both the resistance and susceptible response processes, although it was higher in the resistance response than that in the susceptible response. The total amount of MYB, GAPDH, CatB, Trx and NB-ARC proteins was lower in the resistance than in the susceptible response, but their abundance per unit bacteria in the resistance response was still higher than in the susceptible response, suggesting that these proteins might be positive regulators in the resistance response. In addition, expression of another ERF was induced by inoculation with bacterial blight pathogen, and expression of Zf-LSD1 was activated by wounding stress alone. Interestingly, most proteins showed similar altered expression patterns in the resistance and susceptible responses, but differed to some extents, implying that both responses might share common molecular mechanisms. This study revealed evidence of resistance-related protein expression, providing a foundation for better understanding of their functions.

[Nasal-cardiac reflex initiated by nasal packing (three cases report and literature review)]

OBJECTIVE

To sum up the diagnosis and treatment experience of the nasal-cardiac reflex initiated by postoperative nasal packing.

METHOD

The clinical data of 3 cases with nasal-cardiac reflex initiated by postoperative nasal packing were analyzed retrospectively.

RESULT

In the period of postoperative nasal packing, 3 patients had abruptly drops in heart rate and blood pressure associated with symptoms of autonomic dysfunction such as flustered, chest tightness, tachypnea, body sweating et al. There are no positive signs of pathological significance in the cardiovascular and respiratory system. The reflex had spontaneously to be offset with oxygen, comfort touch therapy, pull out the stuffing, no other special treatment for all cases.

CONCLUSION

The key of the diagnosis for nasal-cardiac reflex is a drop in mean arterial blood pressure (MABP) and the heart rate (HR) more than 20% above the baseline values. The cause of nasal-cardiac reflex initiated by postoperative nasal packing is long-term mechanical pressure on the nasal mucosa and mental factors. Comfort touch therapy and pull out the nasal packing material is effective method to terminate the reflex and the prognosis is good. Correct understanding of the characteristics of the reflex and preventing the occurrence of its adverse consequences have important clinical significance.

Plk1-mediated mitotic phosphorylation of PinX1 regulates its stability

PinX1 was originally identified as a Pin2/TRF1-interacting protein that suppresses telomerase activity via its telomerase inhibitor domain (TID) and regulates the nucleolar localization of TRF1 in telomerase-positive cells. In addition to its telomeric localization, PinX1 can be found in the nucleoli of human cells. Our recent studies have shown that PinX1 localizes to the chromosome periphery and kinetochores in mitosis. Depletion of PinX1 results in lagging chromosomes in mitosis and micronuclei in interphase. However, less is known about the post-translational modification of PinX1 in mitosis. Here, we show that Polo-like kinase 1 (Plk1) is a novel interacting protein of PinX1. Plk1 interacts with and phosphorylates PinX1 in vivo and in vitro. Overexpression of Plk1 promotes protein turnover of PinX1, a process that depends on ubiquitin-associated proteasomal degradation. Depletion of Plk1 using siRNA increases the stability of PinX1 at protein level in mitosis. Moreover, Plk1-mediated phosphorylation of PinX1 at five phosphorylation sites is essential for its Plk1-induced degradation. These findings suggest that Plk1 may negatively regulate the stability of PinX1 by mitotic phosphorylation.

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.

PML3 Orchestrates the Nuclear Dynamics and Function of TIP60

The promyelocytic leukemia (PML) protein is a major component to govern the PML nuclear body (NB) assembly and function. Although it is well defined that PML NB is a site recruiting sumoylated proteins, the mechanism by which PML protein regulates the process remains unclear. Here we show that PML3, a specific PML isoform, interacts with and recruits TIP60 to PML NBs. Our biochemical characterization demonstrates that PML3 physically interacts with TIP60 via its N-terminal 364 amino acids. Importantly, this portion of TIP60 is sufficient to target to the PML NBs, suggesting that PML3-TIP60 interaction is sufficient for targeting TIP60 to the NBs. The PML3-TIP60 interaction is specific, since the region of TIP60 binding is not conserved in other PML isoforms. The physical interaction between PML3 and TIP60 protects TIP60 from Mdm2-mediated degradation, suggesting that PML3 competes with MDM2 for binding to TIP60. Fluorescence recovery after photobleaching analysis indicates that the PML3-TIP60 interaction modulates the nuclear body distribution and mobility of TIP60. Conversely, the distribution and mobility of TIP60 are perturbed in PML3-deficient cells, accompanied by aberrations in DNA damage-repairing response. Thus, PML3 orchestrates the distribution, dynamics, and function of TIP60. Our findings suggest a novel regulatory mechanism by which the PML3 and TIP60 tumor suppressors cooperate to ensure genomic stability.

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.

[Important role of Ser 219 phosphorylation of TRF1 in regulation of cell cycle]

OBJECTIVE

To investigate the role of Ser 219 phosphorylation of TRF1 (telomere repeat binding factor 1) in regulation of cell cycle.

METHODS

The mimicking phosphorylation mutant (TRF1S219D-GFP) and the non-phosphorylatable mutant (TRF1S219A-GFP) were constructed; the mutant genes and corresponding proteins were checked by sequencing and Western blot, respectively. Immunofluorescence staining was performed to detect the localization of mutants in HeLa cells. Cell cycle was analyzed by flow cytometry and ATM level was evaluated by immunoblotting.

RESULTS

The mutant genes were verified by direct sequencing and protein expression of GFP-tagged mutants was confirmed by immunoblotting.TRF1S219A-GFP and TRF1S219D-GFP were both localized in telomere of HeLa cells. Moreover, overexpression of TRF1-GFP or TRF1S219A-GFP resulted in an accumulation of HeLa cells in G2/M (P<0.05). The protein level of ATM was increased when overexpression the wide type or mutants.

CONCLUSION

The Ser 219 phosphorylation of TRF1 by ATM could result in cell cycle arrest in G2/M, which is related to overexpression of TRF1.

[Interaction between a novel centrosomal protein TACP1 and mitotic kinase Nek2A]

OBJECTIVE

To study interaction between a novel centrosomal protein TACP1 and mitotic kinase Nek2A.

METHODS

Nek2A305-446 protein was expressed and purified in E.coli and TACP1 protein was expressed in transfected 293T cells. Pull-down assay was used to examine the interaction between Nek2A305-446 and TACP1. TACP1 and Nek2A complex was tested by co-immunoprecipitation assay with polyclonal anti-TACP1 antibody. The localization of those two proteins in Hela cells was verified by immunofluorescence.

RESULTS

TACP1 was pulled down by Nek2A305-446 protein but not by GST control. Nek2A was co-precipitated with TACP1 protein by polyclonal anti-TACP1 antibody but not by pre-immunization serum. The Immunofluorescence test showed that these two proteins formed a complex at centrosome during mitosis.

CONCLUSION

Centrosomal protein TACP1 is a novel interacting protein with Nek2A, both of which are localized in centrosome during mitosis.

[Localization of p53(301-393) mutant and its effect on mitosis]

OBJECTIVE

To observe the localization of p53(301-393)(residues 301-393) in p53 positive/negative cells and its effect on cell mitosis.

METHODS

The protein expression of p53-GFP and p53(301-393)-GFP was checked by immunoblotting after transfection. Immunofluorescence staining was performed to detect the localization of wide type and mutant in Hela cells (p53 positive) and H1299 cells (p53 negative). The cell morphology of H1299 cells transfected of p53(301-393)-GFP and the cells in mitotic phase were observed. Cell cycle was analyzed by flow cytometry and p53 protein level in HeLa cells was evaluated by Western blot after transfection of p53-GFP and p53(301-393)-GFP.

RESULTS

The protein expression of p53-GFP and p53(301-393)-GFP was verified, p53-GFP was about 90 kMr and p53(301-393)-GFP about 40 kMr. Immunofluorescence microscopy demonstrated that both proteins were diffusely located in the nuclei of HeLa cells and H1299 cells. But different from the p53-GFP, the p53(301-393)-GFP was distributed in the nucleolus of HeLa cells. After transfection of the two plasmids, mitosis was inhibited in H1299 cells and some cells underwent apoptosis. G2/M progression of HeLa cells could be blocked by transfection of p53(301-393)-GFP, but endogenous p53 protein level was not changed.

CONCLUSION

p53(301-393)has a different localization in the p53 positive and p53 negative cells and could inhibit mitosis and cause the cell cycle arrest in G2/M.

Expression, purification, and characterization of Tara, a novel telomere repeat-binding factor 1 (TRF1)-binding protein

Tara was originally identified as a binding protein of guanine nucleotide exchange factor Trio. Although Tara may be involved in many fundamental cellular processes, ranging from actin remodeling, directed cell movement, to cell cycle regulation, aging, and cancer, the exact molecular mechanisms are poorly understood. We expressed recombinant Tara in Escherichia coli and purified the protein to approximately 99% purity using affinity chromatography and gel-filtration chromatography. The identity of the purified protein was confirmed by mass spectrometry. Non-denaturing polyacrylamide gel electrophoresis and gel-filtration chromatography showed that Tara forms multimer in vitro. The purified Tara was used to generate polyclonal antibody, which could specifically recognize both the recombinant and endogenous Tara. Using the pull-down assay, we showed that the purified Tara interacted with TRF1, suggesting that the purified protein is functional and biologically active. The availability of purified Tara and anti-Tara antibody provides critical reagents for elucidating Tara's cellular function and its molecular mechanism.

Study on the expression and mutation of human telomeric repeat binding factor (hTRF1) in 10 malignant hematopoietic cell lines

OBJECTIVE

Detecting the expression and mutation of human telomeric repeat binding factor (hTRF1) in 10 malignant hematopoietic cell line cells on the base of determining its genomic structure and its four pseudogenes to clarify if hTRF1 mutation is one of the factors of the activation of telomerase.

METHODS

hTRF1cDNA sequences were obtained from GenBank, its genome structure and pseudogenes were forecasted by BLAST and other biology information programs and then testified by sequencing. Real-time RT-PCR was used to detect the expression of hTRF1mRNA in 10 cell line cells, including myelogenous leukemia cell lines K562, HL-60, U-937, NB4, THP-1, HEL and Dami; lymphoblastic leukemia cell lines 6T-CEM, Jurkat and Raji. Telomerase activities of cells were detected by using telomeric repeat amplification (TRAP)-ELISA protocol. PCR and sequencing were used to detect mutation of each exon of hTRF1 in 10 cell line cells.

RESULTS

hTRF1 gene, mapped to 8q13, was divided into 10 exons and spans 38.6 kb. Four processed pseudogenes of hTRF1 located on chromosome 13, 18, 21 and X respectively, was named as PsihTRF1-13, PsihTRF1-18, PsihTRF1-21 and PsihTRF1-X respectively. All cell line cells showed positive telomerase activity. The expression of hTRF1 was significantly lower in malignant hematopoietic cell lines cells (0.0338, 0.0108-0.0749) than in normal mononuclear cells (0.0493, 0.0369-0.128) (P=0.004). But no significant mutation was found in all exons of hTRF1 in 10 cell line cells. Four variants were found in part of intron 1, 2 and 8 of hTRF1. Their infection on gene function is unknown and needs further studies.

CONCLUSION

hTRF1 mutation is probably not one of the main factors for telomerase activation in malignant hematopoietic disease.

The Expression of Telomeric Proteins and Their Probable Regulation of Telomerase during the Differentiation of All-trans-Retinoic Acid-Responsive and -Resistant Acute Promyelocytic Leukemia Cells

Telomerase activity has been linked to retinoid induction of tumor cell differentiation, and the patterns of telomerase expression are different in the 2 pathways of acute promyelocytic leukemia (APL) cell differentiation: the retinoic acid receptor 3 (RAR3)-dependent and the retinoic X receptor 3 (RXR3)-dependent pathways. Still, whether telomeric proteins respond to retinoid treatment is not clear. If they do, how they would respond and how they would interfere in telomerase regulation during differentiation are also unclear. Using all-trans-retinoic acid (ATRA)-sensitive and -resistant APL cell lines NB4, NB4-R1, and NB4-R2, we analyzed a panel of telomeric proteins, including TRF1, PINX1, TANK1, and TANK2, at the messenger RNA (mRNA) and protein expression levels during the differentiation of these cell lines in the 2 pathways. Our analyses showed that both mRNA and protein expression of TRF1 remained stable during NB4 and NB4-R1 cell differentiation but slightly increased in NB4-R2 cells, suggesting that TRF1 may have different functions in the RAR3- and RXR3-dependent pathways. The stable expression of TRF1 may be because telomere length remains unchanged. Pinx1 mRNA expression was tightly correlated with telomerase reverse transcriptase (hTERT) mRNA expression during differentiation. Variation in Pinx1 expression may be a reaction induced by hTERT expression variation. TANK1 mRNA expression and TANK1 protein levels were both down-regulated in all 3 APL cell lines at a later period of differentiation, suggesting that TANK1 may positively regulate telomerase activity and that both RAR3- and RXR3-dependent pathways may exert this regulation.TANK2 expression levels remained stable in all 3 APL cell lines during differentiation, showing that TANK2 may have little effect on telomerase. Thus, our studies provide an outline of the dynamics of telomeric protein expression and the probable regulatory effects of these proteins on telomerase during the differentiation of ATRA-responsive and -resistant APL cells.

Stabilization of PML nuclear localization by conjugation and oligomerization of SUMO-3

The PML gene of acute promyelocytic leukemia (APL) encodes a cell-growth and tumor suppressor. PML localizes to discrete nuclear bodies (NBs) that are disrupted in APL cells, resulting from a reciprocal chromosome translocation t (15;17). Here we show that the nuclear localization of PML is also regulated by SUMO-3, one of the three recently identified SUMO isoforms in human cells. SUMO-3 bears similar subcellular distribution to those of SUMO-1 and -2 in the interphase nuclear body, which is colocalized with PML protein. However, both SUMO-2 and -3 are also localized to nucleoli, a region lacking SUMO-1. Immunoprecipitated PML protein bears SUMO-3 moiety in a covalently modified form, supporting the notion that PML is conjugated by SUMO-3. To determine the functional relevance of SUMO-3 conjugation on PML molecular dynamics, we suppressed SUMO-3 protein expression using a siRNA-mediated approach. Depletion of SUMO-3 markedly reduced the number of PML-containing NBa and their integrity, which is rescued by exogenous expression of SUMO-3 but not SUMO-1 or SUMO-2. The specific requirement of SUMO-3 for PML nuclear localization is validated by expression of SUMO-3 conjugation defective mutant. Moreover, we demonstrate that oligomerization of SUMO-3 is required for PML retention in the nucleus. Taken together, our studies provide first line of evidence showing that SUMO-3 is essential for PML localization and offer novel insight into the pathobiochemistry of APL.

[Expression of human telomere repeat binding factor 1 (TRF1) in acute leukemia cells and its correlation with telomerase activities]

OBJECTIVE

To study the expression of human telomere repeat binding factor 1 (TRF1) to investigate the correlation of telomerase activity with acute leukemia.

METHODS

Leukemic cells were collected from 30 cases of acute leukemia. Realtime quantitative PCR with fluorescence probe hybridization was used to measure expression of TRF1 and hTERT mRNA in leukemic cells.

RESULTS

TRF1 mRNA expression was 0.0126 (0.0127-0.0546) in acute non-lymphocytic leukemia (ANLL), which was lower than that in normal mononuclear cells [0.0457 (0.00839-0.262), P<0.001], but its expression in acute lymphoblastic leukemia (ALL) cells [0.0745 (1.92 x 10(-6)-0.193)] had no significant difference compared with that in normal mononuclear cells. TRF1 expression in ANLL cells was significantly lower than that in ALL cells (P=0.001). The expressions of TRF1 mRNA in AL cells and normal mononuclear cells had no significant correlation with expression of hTERT mRNA (r=-0.173, P=0.207).

CONCLUSION

The expression of TRF1 is lower in ANLL cells, which indicates TRF1 may have some effect on telomerase activity by regulating telomere length in ANLL cells.

[Localization of human telomere repeat binding factor 1 in telomerase-positive and-negative cells and its expression during cell cycle]

OBJECTIVE

To observe the distribution pattern of human telomere repeat binding factor 1(TRF1) in the telomerase-positive (HeLa) and telomerase-negative cells (WI38-2RA) and to investigate its expression level during the cell cycle.

METHODS

The full-length sequences of TRF1(TRF1FL) and its mutant with N and C terminus deletion (TRF1DeltaNC) were generated by PCR amplification, the resulting fragments were cloned into pEGFP-C2 mammalian expression vector. GFP-tagged proteins were verified by Western blotting with rabbit anti-TRF1 and mouse anti-GFP antibodies after cell transfection. Immunofluorescence staining were performed to detect the TRF1 localization in HeLa and WI38-2RA cells. Metaphase spreads from HeLa cells were also prepared to observe TRF1 localization in chromosomes. HeLa cells were arrested by thymidine and nocodazole at different cell stages. Cell cycles were analyzed by flow cytometry and TRF1 levels were evaluated by semi-quantitative Western blotting.

RESULTS

TRF1FL and TRF1PNC fragments were sized about 1.3 kb and 0.95 kb. GFP-tagged TRF1FL and TRF1DeltaNC proteins were 80 kD and 60 kD, respectively. In both HeLa and WI38-2RA cells, TRF1FL had a speckled distribution in the nuclei,however, TRF1FL did not coincide with promyelocytic leukemia (PML) nuclear body in HeLa cells while it exclusively did in WI38-2RA cells. Moreover, TRF1FL was exactly localized at the termini of metaphase spreads in HeLa cells. In contrast, TRF1PNC was diffusely distributed throughout the nuclei. Analysis by semi-quantitative Western blotting indicated that TRF1 levels increased with cell cycle progression, which reached the zenith at the M phase and went down to the nadir at G1/S point. The TRF1 level at M phase was about 3.9 times than that at G1/S point(t=12.92iP<0.01).

CONCLUSION

TRF1 has a different localization in telomerase-positive and telomerase-negative cells, which suggests TRF1 might exert different functions in these cells. TRF1 level is regulated with cell cycle.

[Isolation of Tara protein and its gene cloning]

OBJECTIVE

To isolate and identify TRF1 immunoprecipitating protein complex and to clone the candidate gene.

METHODS

The co-immunoprecipitation assay was employed to isolate TRF1 protein complex and the immunoprecipitate was subjected to MALDI-TOF mass spectrometry for protein identification. The candidate gene was amplified by temperature-gradient PCR from human testis cDNA library and then cloned into pEGFP-C2 vector for eukaryotic expression. The amplified gene was verified by direct sequencing and GFP-tagged protein was confirmed by immunoblotting.

RESULTS

Tara protein with the size of 68 kD was identified from the TRF1 precipitate. The candidate gene amplified from cDNA library was about 1.7 kb as expected. Sequencing demonstrated the amplified fragment had 99.9% of homogenesis with Tara CDS sequence (gi:30474869). GFP-tagged fusion protein was about 100 kD. Tara was diffusely distributed in cytoplasm at interphase and in whole cells at mitotic phase.

CONCLUSION

Tara might be an interacting protein with TRF1. However, further investigation would be required to confirm if they were bona fide partners.

[Telomerase activity of human bone marrow mesenchymal stem cells]

OBJECTIVE

To investigate the telomerase activity in mesenchymal stem cells (hMSCs) from human bone marrow after their in vitro committed differentiation into adipocytes and cryopreservation.

METHODS

hMSCs were isolated from human bone marrow. The isolated hMSCs were induced to differentiate into adipocytes in vitro or cryopreserved. TRAP assay (telomerase repeat amplification protocol assay) was employed to detect telomerase activity in those hMSCs.

RESULTS

Telomerase activity (RTA) in hMSCs (n=19) was (1.46 +/-0.67)%, while that in hMSCs-derived adipocytes (n=3) was (11.80 +/-2.52)% (P<0.001). RTA of hMSCs-passage 1.3 (n=10) was (1.46+/-0.83)%, and that of hMSCs-passage 4-7(n=9) was (1.46 +/-0.47)% (P=0.99). Cryopreservation did not affect the telomerase activity in hMSCs, RTA of fresh hMSCs (n=13) was (1.41 +/-0.44)%, RTA of frozen hMSCs (n=6) was (1.57 +/-1.07)% (P=0.64).

CONCLUSION

hMSCs are telomerase-negative, but telomerase activity in hMSCs-derived adipocytes is upregulated.

[Expression of Pin1 in malignant hematopoietic cells and its relation with cell cycle]

OBJECTIVE

To study the expression of peptidyl-prolyl cis/trans isomerase (PPIase or Pin1) in malignant hematopoietic cells and its relation with cell cycle.

METHODS

Realtime quantitative PCR with fluorescence probe hybridization was used to measure expression of Pin1 mRNA in malignant hematopoietic cell lines and normal mononuclear cells separated from bone marrow. HeLa cells were blocked with Thymidine and Nocodazole in different cell phases and then the expression of Pin1 mRNA and protein were detected by realtime-PCR and immunoblotting.

RESULTS

The expression of Pin1 in malignant hematopoietic cell lines was significantly higher than that in normal controls (0.339 +/-0.093 compared with 0.038 +/-0.005, P<0.01). Its expression in myeloid malignant hematopoietic cell lines was significantly higher than that in normal controls (0.388 +/-0.115 compared with 0.038 +/-0.005, P<0.01) and so was the malignant lymphocytic cell lines (0.226 +/-0.166 compared with 0.038 +/-0.005, P<0.01). The expression of Pin1 was closely correlated with cell cycle. It was the highest in G1 phase and the lowest in S phase (110.762 +/-16.737 compared with 4.080 +/-0.634, P<0.01).

CONCLUSION

Pin1 is overexpressed in malignant hematopoietic cell lines and its expression is different during cell cycle that is highest in G1 phase and lowest in S phase.