Post-translational Modifications of PML in Regulating the Functions of Nuclear Bodies --Review / 中国实验血液学杂志

Abstract　　The promyelocytic leukemia (PML) gene encoded PML protein as a tumor suppressor protein, plays important roles in the occurrence and development of various cancers including acute promyelocytic leukemia. Recent studies have indicated that there are a variety of post-translational modifications of the PML protein, such as SUMOylation, ubiquitination, phosphorylation, and acetylation in cells. These modifications of the PML protein can directly affect the formation of PML nuclear bodies (PML-NBs), repair DNA damage, and modulate cell apoptosis. Furthermore, the abnormal modifications of PML not only result in the occurrence of hematopoietic tumors, but also are closely related to the drug-resistance of cancer. Therefore, investigating the post-translational modifications of PML is significant to uncover the mechanism of formation and functions of PML-NBs, thus contributing to the prevention and treatment of related hematopoietic tumors. In this review, the characteristics of the post-translational modifications of PML protein and the relationship between these modifications and functions of PML-NBs are summarized so as to provide the potential targets for the treatment of related cancers.

Unraveling the chromosome higher-order structures in the transcriptional regulation of hematopoiesis by chromosome conformation capture / 中国实验血液学杂志

Emerging evidence has demonstrated that genomes are organized into higher-order structures in vivo and long range interactions between genomic regions largely contribute to the regulation of gene expression. Hematopoiesis, orchestrated by the precise spatial regulation and organization of hematopoietic transcription factors, serves as a good model for exploring these issues. The chromosome conformation capture (3C) methodology and its high throughput based technology provide an innovative solution for analyzing the regulation of functional elements through inter-chromosomal and intra-chromosomal interactions, and contacts of functional components in nuclei, thus leading to a more comprehensive understanding of human genome and gene expression. This review focuses on the recent progress of 3C and its derivatives, and their applications in unraveling the mechanisms of transcriptional regulation in hematopoiesis.

Transcriptional regulation of BHLHB2 induced by PML-RARα / 中国实验血液学杂志

Objective of this study was to investigate the transcriptional regulation of BHLHB2 gene by the PML-RARα fusion protein in APL cells and reveal the pathogenesis of APL. RT-PCR was performed to detect the expression change of BHLHB2 before and after the induction of PML-RARα in PR9 cells, and its expression level after the treatment of ATRA in PR9 and APL patient derived NB4 cells. Chromatin immunoprecipitation (ChIP)-based PCR was used to analyze whether the BHLHB2 promoter could be bound by PML-RARα in vivo. A large-scale gene expression profile dataset was used to observe the expression pattern of BHLHB2 in AML. The results showed that the expression level of BHLHB2 was significantly reduced with the induction of PML-RARα and ATRA could reverse this inhibition in both PR9 and NB4 cells and increase the expression of BHLHB2. However, the expression of BHLHB2 could not be induced by ATRA in U937 cells which do not express PML-RARα. Mechanism study revealed that PML-RARα could bound to the promoter of BHLHB2 in vivo to regulate the the expression of BHLHB2. It was found that the expression of BHLHB2 was relatively lower in APL as compared with other subtypes of AML and normal bone marrow cells. It is concluded that BHLHB2 is the target of PML-RARα, and the expression of BHLHB2 is inhibited by PML-RARα through binding to its promoter in APL.

Expression of human Jagged-1 protein on eukaryotic cells and establishment of stable transfectant cell line / 中国实验血液学杂志

Jagged-1 protein is one of the ligands belonging to Notch signaling pathway. Notch signaling pathway is one of the major signaling pathways mediated by contact between cells and plays an important role to regulate the process of proliferation and differentiation of hematopoietic cells in the hematopoietic microenvironment. To study the biological effect after the combination of receptor and ligand in Notch signaling pathway and the mechanism of Notch signaling pathway in bone marrow stromal cells mediated-drug resistance, a NIH-3T3 cell line over-expressing Jagged-1 protein was constructed for further research purposes. A full coding region of Jagged-1 gene was cloned and inserted into eukaryotic expression plasmid to construct pEGFP-IRES2-Jagged-1 eukaryotic expression vector, then transfected into NIH-3T3 cell line, a mammalian cells. As a result Western blot analysis confirmed that the transfectant NIH-3T3 cells highly expressed Jagged-1 protein and flow cytometry analysis confirmed that the NIH-3T3-pEGFP-IRES2-Jagged-1 cell line over-expressed Jagged-1 protein was monoclonal after screened by selective medium and limiting dilution analysis. It is concluded that the pEGFP-IRES2-Jagged-1 eukaryotic expression vector and a stable transfectant monoclonal NIH-3T3 cell line are successfully established. The construction of the stable transfectant monoclonal NIH-3T3 cell line which overexpressed Jagged-1 protein, provides the conditions to further study the mechanism of the bone marrow stromal cell-mediated drug resistance and to discover the new drug targets.

Influence of AML1 and AML1-ETO on transcriptional regulation of nucb2 gene / 中国实验血液学杂志

This study was purposed to investigate the effect of AML1-ETO fusion protein resulted from hematopoietic transcription factor (AML1) and acute myeloid leukemia M(2b)(AML-M(2b)) on transcription activity of nucleobindin 2 (nucb2) promoter, and to explore the role of AML1-ETO in molecular pathogenesis of AML-M(2b). The real-time RT-PCR was used to study the regulation of AML1-ETO on nucb2 at transcription level in AML1-ETO inducible leukemia cell line, the chromatin immunoprecipitation (ChIP)-based qPCR was used to investigate the direct in vivo interaction between the AML1, AML1-ETO and nucb2 promoter in AML1-ETO positive leukemia cell line, the luciferase report gene assay was used to detect the regulation of AML1, AML1-ETO on the transcription activity of nucb2 promoter. The results showed that the expression level of nucb2 was reduced with the increase of AML1-ETO. The promoter of nucb2 could be bound by both AML1 and AML1-ETO. The promoter of nucb2 was trans-repressed by AML1 and AML1-ETO respectively. It is concluded that the nucb2 is the direct target gene of AML1 and AML1-ETO, the transcription regulation of AML1, AML1-ETO on nucb2 is carried out via repressing its promoter activity.

Analysis of gene expression profiles in gastric cancer cell cycle / 中华肿瘤杂志

<p><b>OBJECTIVE</b>To detect the gene expression profile in gastric cancer cell cycle and explain the mechanism of gastric cancer cell proliferation by a genomic study.</p><p><b>METHODS</b>Gastric cancer cells MKN45 were synchronized at G2/M and G1/S point by nocodazole-thymidine and double thymidine methods. The synchronizing degree of cells was monitored by flow cytometry. The gene expression profiles at G2/M point, M/G1 transition, G1 early phase, G1 late phase, G1/S point, S early phase, S late phase, G2 early phase and G2 late phase in MKN45 cell cycling were examined using cDNA microarray chips. Hierarchy analysis was conducted with a professional software package and the up-regulated genes at G1 late and G2 phase were analyzed according to gene database. Furthermore, the mRNA level of cyclin E, cyclin B, plk1 and STK15 in above mentioned nine points were measured by quatitative PCR.</p><p><b>RESULTS</b>2001 genes were detected to be available at all 9 points via software processing, out of which 959 appeared up-regulated or down-regulated. 379 genes showed to be up-regulated at late G1 (147) or G2 phases (232), 40 at S and M phases (also up-regulated at G1 late and G2 phases). The 147 up-regulated genes at G1 late phase are involved in DNA metabolism, transcription and translation, protein transportation, ubiquitination and signal transduction, etc. The 232 up-regulated genes in G2 phase are involved in RNA synthesis and processing, intracellular protein transportation, cytoskeleton synthesis, signal transduction, apoptosis and anti-apoptosis, transcription regulation, ubiquitination, mitosis regulation and oncogene expression, etc. The mRNA level of 4 genes detected by quantitative PCR during cell cycle was in agreement with that detected by microarray.</p><p><b>CONCLUSION</b>During MKN45 cell cycling, the preparation for DNA synthesis and chromosome separation are conducted in G1 and G2, which are implicated in multiple genes, may be the main impetus of driving MKN45 cell cycle. Some of these genes may be related to tumor over-proliferation. The cDNA microarray technique has characteristic features such as reliability and can provide a great deal for future research on cell cycle related genes in gastric cancer.</p>

Mechanisms of fenretinide-triggered apoptosis in leukemic cells / 中国实验血液学杂志

The retinoid N-4-hydroxyphenyl retinamide (4-HPR also known as fenretinide), a synthetic derivative of all trans retinoic acid (ATRA), has shown as an efficient chemopreventive, chemotherapeutic agent and a potent inducer of apoptosis in various cancer cell types in vitro, including leukemic cells. However the mechanisms by which 4-HPR has the apoptotic effects is not completely elucidated. This study was aimed to investigate the effect of 4-HPR on several leukemic cells and explore its mechanisms of effect on U937 cells. The cell growth and proliferation experiments were performed [corrected] cell apoptosis was detected by annexin V; reactive oxygen species (ROS) and mitochondrial transmembrane potential (DeltaPsim) were determined; protein [corrected] expression was detected by Western blot. The results showed that 4-HPR inhibited the proliferation of U937 cells in a dose- and time-dependent manner. 4-HPR markedly [corrected] induced apoptosis in U937 cells, triggered the generation of ROS, induced the loss of mitochondrial transmembrane potential, decreased the expression of procaspase-8 and procaspase-3. Pretreatment of L-ascorbic acid suppressed the generation of ROS, disruption of mitochondrial potential, activation of caspases and apoptosis. It is concluded that the generation of ROS followed by the disruption of mitochondrial transmembrane potential plays an important role on 4-HPR-induced apoptosis in leukemic cells, suggesting that 4-HPR may be one of mitochondrial-targeted agents with clinical potential in treating cancer.

Analysis of gene expression profile of G1/S transition in gastric cancer cell cycle / 中华胃肠外科杂志

<p><b>OBJECTIVE</b>To detect the variation of gene expression profile of G1/S transition and elucidate the role of related genes regulating cell cycle from G1 to S phase in gastric cancer.</p><p><b>METHODS</b>Nocodazole-thymidine and double thymidine methods were used to synchronize gastric cells at G2/M and G1/S point, cDNA microarray chips was applied to examine the gene expression profile at G1 early and late phase, S early and late phase during the cell cycle, hierarchy analysis was conducted by a professional software package.</p><p><b>RESULTS</b>A total of 2001 genes were detected available, 959 genes appeared to be upregulated or downregulated, including 147 genes upregulated at G1 late phase. These 147 genes are involved in DNA metabolism, transcription and translation,posttranslational modification, ubiquitination, signal transduction etc, which all affected cell cycle from different aspects.</p><p><b>CONCLUSION</b>Complex multiple gene processes, such as DNA metabolism, transcription and translation, posttranslational modification, ubiquitination, signal transduction etc,are implicated in and also essential for G1/S transition during gastric cancer cell cycle, part of these genes are significantly associate with overproliferation in gastric cancer.</p>

Establishment of CPP-SOM integrated cDNA microarray technology / 中华医学遗传学杂志

<p><b>OBJECTIVE</b>To get an insight into the molecular mechanisms of diseases development and targeted therapy at the transcriptome level and search for potential therapeutic targets.</p><p><b>METHODS</b>The present researchers established a cDNA microarray platform and applied component plane presentation integrated self-organizing map (CPP-SOM) to the microarray data obtained from a differentiation model, all trans retinoic acid-induced differentiation in NB4 cells.</p><p><b>RESULTS</b>The platform included 12630 unique clones, including 9436 known genes. By CPP-SOM, the researchers were able to not only well classify the regulated genes into functionally distinct categories but also depict transcriptional changes throughout the process of the development of diseases or drug treatment.</p><p><b>CONCLUSION</b>The platform has proven to be steady and reliable, and the CPP-SOM could serve as an important and good tool for analysis of microarray data.</p>