Aibin Liang

Proteomic Analysis Identified DJ-1 as a Cisplatin Resistant Marker in Non-Small Cell Lung Cancer

The aim of study is to identify cisplatin-resistance associated biomarkers for non-small cell lung cancers (NSCLC). We use two-dimensional electrophoresis (2-DE) combined with MALDI-TOF mass spectrometry to compare the proteome between lung cancer cell line A549 and its cisplatin-resistant subline A549/DDP. Nine cisplatin resistance-related proteins were identified, and DJ-1, one of the differently expressed proteins, was selected for further validation and evaluation. Immunohistochemical results demonstrated that high expression level of DJ-1 was associated with cisplatin resistance and a predictor for poor prognosis in 67 locally advanced NSCLC patients. Furthermore, in vitro results showed that silencing DJ-1 increased the proliferation inhibitory effect of cisplatin to A549/DDP cells. In conclusion, DJ-1 might play an important role in the resistibility to cisplatin, and it could also act as a novel candidate biomarker for predicting the response of NSCLC patients to cisplatin-based chemotherapy.

Down-regulation of SENP1 expression increases apoptosis of Burkitt lymphoma cells.

OBJECTIVE To investigate the effect of down-regulation of Sentrin/SUMO-specific protease 1 (SENP1) expression on the apoptosis of human Burkitt lymphoma cells (Daudi cells) and potential mechanisms. METHODS Short hairpin RNA (shRNA) targeting SENP1 was designed and synthesized and then cloned into a lentiviral vector. A lentiviral packaging plasmid was used to transfect Daudi cells (sh-SENP1-Daudi group). Daudi cells without transfection (Daudi group) and Daudi cells transfected with blank plasmid (sh-NC-Daudi group) served as control groups. Flow cytometry was performed to screen GFP positive cells and semiquantitative PCR and Western blot assays were employed to detect the inference efficiency. The morphology of cells was observed under a microscope before and after transfection. Fluorescence quantitative PCR and Western blot assays were conducted to measure the mRNA and protein expression of apoptosis related molecules (caspase-3, 8 and 9). After treatment with COCl2 for 24 h, the mRNA and protein expression of hypoxia inducible factor -1α (HIF-1α) was determined. RESULTS Sequencing showed the expression vectors of shRNA targeting SENP1 to be successfully constructed. Following screening of GFP positive cells by FCM, semiqualitative PCR showed the interference efficiency was 79.2±0.026%. At 48 h after transfection, the Daudi cells became shrunken, had irregular edges and presented apoptotic bodies. Western blot assay revealed increase in expression of caspase-3, 8 and 9 with prolongation of transfection (P<0.05). Following hypoxia treatment, mRNA expression of HIF-1α remained unchanged in three groups (P>0.05) but the protein expression of HIF-1α markedly increased (P<0.05). However, in the sh-SENP1-Daudi group, the protein expression of HIF-1α remained unchanged. CONCLUSION SENP1-shRNA can efficiently inhibit SENP1 expression in Daudi cells. SENP1 inhibition may promote cell apoptosis. These findings suggest that SENP1 may serve as an important target in the gene therapy of Burkitts lymphoma.

Nanocomposite-siRNA approach for down-regulation of VEGF and its receptor in myeloid leukemia cells

BACKGROUND Efficient modulation of aberrant vascular endothelial growth factor (VEGF) and its receptor-1 (Flt-1) expressions have become a potential therapeutic strategy for hematologic malignancies including myeloid leukemia. In this study, we explored the safety and efficacy of chitosan nanoparticle siRNA-VEGF and Flt-1 in leukemic U973 cells. METHODS Cell transfection efficiencies were analyzed by fluorescence microscope, quantitative Real Time PCR; cell growth inhibitory rates were analyzed by CCK-8 assays and flow cytometry. RESULTS siRNA-coated chitosan nanosphere transfection led to 65%, Lipofectamine 2000 to 50% and adenovirus to 90% transfection efficiencies. Three days after transfection of U973 cells, the siRNA induced gene silencing rates of VEGF and Flt-1 were 68% and 65% in the adenovirus, 45% and 43% in the chitosan nanoparticle group. The cell growth inhibitory rates were 34.73% for VEGF and 27.61% for Flt-1 silencing in the adenovirus and 27.04% for VEGF and 21.49% for Flt-1 silencing in the chitosan nanoparticle group. CONCLUSION Chitosan nanoparticle siRNA technology can effectively inhibit the expression of VEGF and its receptor in leukemic cells, which led to suppression of their proliferation. Though less efficient than adenoviruses, their non-viral properties suggest that chitosan nanoparticle siRNA complex gene silencing is suitable for further trials.

SIRT1 downregulation enhances chemosensitivity and survival of adult T-cell leukemia-lymphoma cells by reducing DNA double-strand repair

Most chemotherapy drugs used for the treatment of adult T-cell leukemia-lymphoma (ATL) cause cell death directly by inducing DNA damage, which can be repaired via several DNA repair pathways. Enhanced activity of DNA damage repair systems contributes to ATL resistance to chemotherapies. Targeting DNA repair pathways is a promising strategy for the sensitization of ATL cells to chemotherapeutic drugs. in the present study, inhibition of SIRT1 deacetylase by shRNA sensitized Jurkat cells to etoposide by reducing the activity of non-homologous end joining (NHEJ) and homologous recombination (HR). Silencing of SIRT1 deacetylase by shRNA resulted in enhanced apoptosis and cell cycle arrest, while reduced colony formation of Jurkat cells after etoposide treatment was accompanied by elevated acetylation of FOXO1. Furthermore, inhibition of SIRT1 led to decreased activity of DNA damage repair by NHEJ and HR, accompanied by increased Ku70 acetylation. Furthermore, SIRT1 downregulation prolonged the survival time of Jurkat-xenografted mice. These results suggested that SIRT1 promotes DNA double‑strand repair pathways in Jurkat cells by deacetylating Ku70, and increases cell proliferation by deacetylating FOXO1. The results suggest that SIRT1 is a potential target for the development of combinatorial treatment for ATL.

Retrospective comparison of fludarabine in combination with intermediate-dose cytarabine versus high-dose cytarabine as consolidation therapies for acute myeloid leukemia.

AbstractThis retrospective study compared efficacy and safety of fludarabine combined with intermediate-dose cytarabine (FA regimen) versus high-dose cytarabine (HiDAC regimen) as consolidation therapy in acute myeloid leukemia (AML) patients who achieved complete remission.Disease-free survival (DFS) and overall survival (OS) based on age (≥60, <60 years) and cytogenetics were evaluated from data between January 2005 and March 2013.Total 82 patients (FA, n = 45; HiDAC, n = 37; 14–65 years) were evaluated. Five-year DFS was 32.0% and 36.2% for FA and HiDAC groups, respectively (P = 0.729), and 5-year OS was 39.5% and 47.8% (P = 0.568), respectively. Among older patients (≥60 years), 3-year DFS was 26.0% for FA group and 12.5% for HiDAC group (P = 0.032), and 3-year OS was 34.6% and 12.5%, respectively (P = 0.026). In FA group, hematological toxicities were significantly lower. FA regimen was as effective as HiDAC regimen in patients with good/intermediate cytogenetics and significantly improved DFS and OS in older patients.

Genetic inhibition of vascular endothelial growth factor receptor-1 significantly inhibits the migration and proliferation of leukemia cells and increases their sensitivity to chemotherapy

Little is known about the role of vascular endothelial growth factor (VEGF) receptor-1 (VEGFR-1) in acute leukemia. In this study, using real-time PCR and ELISA, we found that VEGF and VEGFR-1 are highly expressed in U937 leukemia cells and primary leukemia cells (M4/M5 subtypes), which are associated with an increased migration rate and extramedullary disease. In order to elucidate the role of VEGFR-1 in acute leukemia, we used a lentivirus-mediated shRNA expression system to specifically inhibit VEGFR-1 expression in the U937 cell line. In addition, a series of in vitro experiments were conducted, including cell proliferation and migration assays and drug treatments. Our results showed that shRNA reduced the proliferation and migration of U937 cells. RNA interference targeting VEGFR-1 in combination with bevacizumab did not exert synergistic antitumor effects. However, shRNA enhanced the sensitivity of the U937 cells to cytarabine by decreasing the IC50 of cytarabine, reducing the number of cells in the S phase and suppressing the expression of the survivin gene. Taken together, these results suggest that VEGFR-1 interference may serve as a novel antitumor therapeutic strategy for the treatment of leukemia.

N-Propionyl polysialic acid precursor enhances the susceptibility of multiple myeloma to antitumor effect of anti-NprPSA monoclonal antibody.

Aim:To study the antitumor effect of anti-NprPSA monoclonal antibody (mAb) in combination with ManNPr, a precursor of N-propionyl PSA, in multiple myeloma (MM), and to explore the mechanisms of the action.Methods:Human multiple myeloma cell line RPMI-8226 was tested. The cells were pre-treated with ManNPr (1, 2, and 4 mg/mL), and then incubated with anti-NprPSA mAb (1 mg/mL). Cell apoptosis in vitro was detected using MTT assay and flow cytometry. BALB/c nude mice were inoculated sc with RPC5.4 cells. On 5 d after the injection, the mice were administered sc with anti-NprPSA mAb (200 μg/d) and ManNPr (5 mg/d) for 8 d. The tumor size and body weight were monitored twice per week. TUNEL assay was used for detecting apoptosis in vivo. The apoptotic pathway involved was examined using Western blot analysis and caspase inhibitor.Results:Treatment of RPMI-8226 cells with anti-NprPSA mAb alone failed to inhibit cell growth in vitro. In RPMI-8226 cells pretreated with ManNPr, however, the mAb significantly inhibited the cell proliferation, decreased the viability, and induced apoptosis, which was associated with cleavage of caspase-3, caspase-8, caspase-9, and poly(ADP-ribose) polymerase. In the mouse xenograft model, treatment with the mAb in combination with ManNPr significantly inhibited the tumor growth, and induced significant apoptosis as compared to treatment with the mAb alone. Moreover, apoptosis induced by the mAb in vivo resulted from the activation of the caspases and poly(ADP-ribose) polymerase.Conclusion:The anti-NprPSA mAb in combination with ManNPr is an effective treatment for in vitro and in vivo induction of apoptosis in multiple myeloma.

A three‑lncRNA signature for prognosis prediction of acute myeloid leukemia in patients

Long non-coding RNAs (lncRNAs) are transcripts characterized by >200 nucleotides, without validated protein production. Previous studies have demonstrated that certain lncRNAs have a critical role in the initiation and development of acute myeloid leukemia (AML). In the present study, the subtype-specific lncRNAs in AML was identified. Following the exclusion of the subtype-specific lncRNAs, the prognostic value of lncRNAs was investigated and a three-lncRNA expression-based risk score [long intergenic non-protein coding RNA 926, family with sequence similarity 30 member A and LRRC75A antisense RNA 1 (LRRC75A-AS1)] was developed for AML patient prognosis prediction by analyzing the RNA-seq data of AML patients from Therapeutically Available Research to Generate Effective Treatments (TARGET) and The Cancer Genome Atlas (TCGA) projects. In the training set obtained from TARGET, patients were divided into poor and favorable prognosis groups by the median risk score. The prognostic effectiveness of this lncRNA risk score was confirmed in the validation set obtained from TCGA by the same cut-off. Furthermore, the lncRNA risk score was identified as an independent prognostic factor in the multivariate analysis. As further verification of the independent prognostic power of the lncRNA risk score, stratified analysis was performed by a cytogenetics risk group and revealed a consistent result. The prognostic predictive ability of the risk score was compared with the cytogenetics risk group by time-dependent receiver operating characteristic curves analysis. It was revealed that the combination of the lncRNA risk score and cytogenetics risk group provided a higher prognostic value than a single prognostic factor. The present study also performed co-expression analysis to predict the potential regulatory mechanisms of these lncRNAs in a cis/trans/competing endogenous RNA manner. The results suggested that LRRC75A-AS1 was highly associated with the target genes of transcription factors tumor protein 53 and ETS variant 6. Overall, these results highlighted the use of the three-lncRNA expression-based risk score as a potential molecular biomarker to predict the prognosis in AML patients.

SIRT1 Involved in the Regulation of Alternative Splicing Affects the DNA Damage Response in Neural Stem Cells

Background/Aims: Alternative splicing and DNA damage exhibit cross-regulation, with not only DNA damage inducing changes in alternative splicing, but alternative splicing itself possibly modulating the DNA damage response (DDR). Sirt1, a prominent anti-aging player, plays pivotal roles in the DDR. However, few studies have examined alternative splicing with DNA damage in neural stem cells (NSCs) and, in essence, nothing is known about whether SIRT1 regulates alternative splicing. Hence, we investigated the potential involvement of Sirt1-mediated alternative splicing in the NSC DDR. Methods: Genome-wide alternative splicing profiling was performed upon DNA damage induction and SIRT1 deletion. Results: DNA damage caused genome-wide changes in alternative splicing in adult NSCs and Sirt1 deficiency dramatically altered DDR-related alternative splicing. In particular, extensive alternative splicing changes in DDR-related processes such as cell cycle control and DNA damage repair were observed; these processes were dramatically influenced by Sirt1 deficiency. Phenotypically, Sirt1 deficiency altered the proliferation and DNA repair of adult NSCs, possibly by regulating alternative splicing. Conclusion: SIRT1 helps to regulate alternative splicing, which itself affects the DDR of NSCs. Our findings provide novel insight into the mechanisms underlying the DDR in stem cells.

KU70 Inhibition Impairs Both Non-Homologous End Joining and Homologous Recombination DNA Damage Repair Through SHP-1 Induced Dephosphorylation of SIRT1 in Adult T-Cell Leukemia-Lymphoma Cells

Background/Aims: Adult T-cell leukemia-lymphoma (ATL) is an aggressive disease which is highly resistant to chemotherapy. Studies show that enhanced ability of DNA damage repair (DDR) in cancer cells plays a key role in chemotherapy resistance. Here, we suggest that defect in DDR related genes might be a promising target to destroy the genome stability of tumor cells. Methods: Since KU70 is highly expressed in Jurkat cells, one of the most representative cell lines of ATL, we knocked down KU70 by shRNA and analyzed the impact of KU70 deficiency in Jurkat cells as well as in NOD-SCID animal models by western blot, immunofluorescence, flow cytometry and measuring DNA repair efficiency. Results: It is observed that silencing of KU70 resulted in accumulated DNA damage and impaired DDR in Jurkat cells, resulting in more apoptosis, decreased cell proliferation and cell cycle arrest. DNA damage leads to DNA double-strand breaks (DSBs), which are processed by either non-homologous end joining(NHEJ) or homologous recombination(HR). In our study, both NHEJ and HR are impaired because of KU70 defect, accompanied with increased protein level of SHP-1, a dephosphorylation enzyme. In turn, SHP-1 led to dephosphorylation of SIRT1, which further impaired HR repair efficiency. Moreover, KU70 deficiency prolonged survival of Jurkat-xenografted mice. Conclusion: These findings suggest that targeting KU70 is a promising target for ATL and might overcome the existing difficulties in chemotherapy.