NUP98-HMGB3: a novel oncogenic fusion

HMGB3 is a Potential Therapeutic Target by Affecting the Migration and Proliferation of Colorectal Cancer

Colorectal cancer is one of the common malignant tumors in the digestive system, with high incidence and mortality rate. Therefore, there is an urgent need to identify and develop new molecular targets for colorectal cancer treatment. Previous studies have pointed out the important role of HMGB3 in tumors, and how it works in colorectal cancer needs to be studied in depth. In this study, we found that HMGB3 was highly expressed in COAD in the cBioPortal and GEPIA2 databases. Kaplan-Meier analysis showed that compared with patients with lower HMGB3 levels, patients with higher HMGB3 levels had poorer OS (p = 0.001). We also found a correlation between HMGB3 expression and immune infiltration of CRC. To investigate the mechanism of HMGB3 knockdown-mediated colorectal cancer inhibition, we detected a downregulation of N-cadherin, Vimentin and β-catenin proteins after knockdown of HMGB3. Taken together, HMGB3 can be an effective target for CRC treatment in the future, and we have reason to believe that HMGB3 will be of greater value in more tumors in the near future.

Bioinformatics analysis of the expression and clinical significance of the NUP210 Gene in acute myeloid leukaemia

: Nucleoporin 210 (NUP210) is a membrane-spanning nuclear protein known to be involved in the development of solid tumours; however, its role in haematological cancers has not been investigated. This study aimed to assess the expression and prognostic potential of NUP210 gene expression in patients with acute myeloid leukaemia (AML).

: In this study, we assessed the expression and prognostic potential of NUP210 gene expression in patients with AML through bioinformatics analysis of The Cancer Genome Atlas and Genotype-Tissue Expression databases.

:The expression of NUP210 mRNA in bone marrow was significantly increased in patients with AML compared to that in healthy individuals and was correlated with AML subtypes according to French-American-British classification as well as with bone marrow blast counts and patient sex (P < 0.05). The high NUP210 expression level was an independent biomarker of poor prognosis in the total AML population (P < 0.05) and separately in female but not male patients.

: Our results of NUP210 mRNA analyses revealed, for the first time, that NUP210 transcription was upregulated in patients with AML and positively associated with unfavourable AML prognosis, suggesting that NUP210 expression can be used as guidance in patient stratification for targeted therapy.

HMGB3 promotes PARP inhibitor resistance through interacting with PARP1 in ovarian cancer

Poly (ADP-ribose) polymerase (PARP) inhibitor (PARPi) resistance remains a therapeutic challenge in ovarian cancer. High-mobility group box 3 (HMGB3) plays significant roles in the development of drug resistance of many cancers. However, the function of HMGB3 in PARPi resistance is poorly understood. In the current study, we clarified that HMGB3 was aberrantly overexpressed in high-grade serous ovarian carcinoma (HGSOC) tissues, and high HMGB3 levels indicated shorter overall survival and drug resistance in HGSOC. The overexpression of HMGB3 increased the insensitivity of ovarian cancer to PARPi, whereas HMGB3 knockdown reduced PARPi resistance. Mechanistically, PARP1 was identified as a novel interaction partner of HMGB3, which could be blocked using olaparib and was enhanced upon DNA damage conditions. We further showed that loss of HMGB3 induced PARP1 trapping at DNA lesions and inhibited the PARylation activity of PARP1, resulting in an increased DNA damage response and cell apoptosis. The PARPi-resistant role of HMGB3 was also verified in a xenograft mouse model. In conclusion, HMGB3 promoted PARPi resistance via interacting with PARP1, and the targeted inhibition of HMGB3 might overcome PARPi resistance in ovarian cancer therapy.

LINC00857 promotes colorectal cancer progression by sponging miR-150-5p and upregulating HMGB3 (high mobility group box 3) expression

Colorectal cancer (CRC) is the third most commonly diagnosed malignant tumor worldwide. LINC00857 has been reported as a dysregulated long non-coding RNAs (lncRNAs) involved in the genesis and development of different cancers. In CRC, accumulating evidence indicates that high mobility group box 3 (HMGB3) is over-expressed and contributes to CRC development. However, the mechanism underlying HMGB3 upregulation in CRC remains unclear. The present work aims to investigate the role of LINC00857 and its functional interaction with HMGB3 in regulating CRC progression. Differential expression of LINC00857 between CRC tissues and normal tissues was identified in TCGA (The Cancer Genome Atlas) database. In vitro functional assays were performed to explore the biological functions of LINC00857 in CRC cells. In vivo xenograft model was employed to investigate the role of LINC00857 in CRC tumorigenesis. We found that LINC00857 was significant upregulated in CRC tissues and cell lines. LINC00857 knockdown significantly inhibited the proliferation, migration and invasion of CRC cells, and also induced apoptosis. Moreover, LINC00857 knockdown suppressed CRC tumorigenesis in vivo. We further demonstrated that the effects of LINC00857 in CRC cells were mediated through miR-150-5p/HMGB3 axis. LINC00857 negatively regulates the activity of miR-150-5p, which releases its inhibition on HMGB3 expression. Our data indicate that LINC00857/miR-150-5p/HMGB3 axis plays a fundamental role in regulating the malignant phenotype and tumorigenesis of CRC. Targeting this axis may serve as novel therapeutic strategies for CRC treatment.

MicroRNA-429 acts as a tumor suppressor in colorectal cancer by targeting high mobility group box 3

Colorectal cancer (CRC) is one of the most common solid tumors worldwide and has an extremely poor prognosis. MicroRNA-429 (miR-429) has been reported to participate in the progression of CRC. However, the pathological mechanisms require further investigation. The aim of the present study was to investigate the association between miR-429 and high mobility group box 3 (HMGB3) in CRC and the associated mechanism. The mRNA expression levels of miR-429 and HMGB3 in 65 paired CRC and adjacent tissues were examined by reverse transcription-quantitative PCR. Furthermore, a dual-luciferase reporter assay was performed to identify the association between miR-429 and HMGB3. Finally, the effects of miR-429 and HMGB3 on the proliferation and apoptosis of CRC cells were detected. As a result, it was identified that miR-429 expression was downregulated and HMGB3 expression was upregulated in CRC tissues compared with in adjacent non-cancer tissues, and the expression levels of miR-429 were negatively associated with those of HMGB3. Notably, HMGB3 was demonstrated to be a direct target of miR-429 by dual-luciferase reporter assay. Furthermore, transfection with a miR-429 mimic significantly inhibited HMGB3 expression and led to decreased proliferation and increased apoptosis of CRC cells. On the other hand, transient overexpression of HMGB3 partially inhibited the antitumor effects of miR-429. To the best of our knowledge, the present study demonstrated for the first time that miR-429 regulated the proliferation and apoptosis of CRC cells via HMGB3, suggesting a specific tumor suppressive function of the miR-429/HMGB3 signaling pathway in CRC.

The role of high mobility group protein B3 (HMGB3) in tumor proliferation and drug resistance

The high mobility group protein B (HMGB) family (including HMGB1, HMGB2, HMGB3, and HMGB4) can regulate the mechanisms of DNA replication, transcription, recombination, and repair, and act as cytokines to mediate responses to infection, injury, and inflammation. HMGB1/2/3 has a high similarity in sequence and structure, while HMGB4 has no acidic C-terminal tail. Among them, HMGB3 can regulate the self-renewal and differentiation of normal hematopoietic stem cell population, but the decrease of its expression is easy to induce leukemia. Up-regulation of its expression promotes tumor development and chemotherapy resistance through a variety of mechanisms, and non-coding RNA can regulate to promote tumor cell proliferation, invasion, and migration and inhibit cancer cell apoptosis.

Mechanistic insights and potential therapeutic approaches for NUP98-rearranged hematologic malignancies

Nucleoporin 98 (NUP98) fusion oncoproteins are observed in a spectrum of hematologic malignancies, particularly pediatric leukemias with poor patient outcomes. Although wild-type full-length NUP98 is a member of the nuclear pore complex, the chromosomal translocations leading to NUP98 gene fusions involve the intrinsically disordered and N-terminal region of NUP98 with over 30 partner genes. Fusion partners include several genes bearing homeodomains or having known roles in transcriptional or epigenetic regulation. Based on data in both experimental models and patient samples, NUP98 fusion oncoprotein-driven leukemogenesis is mediated by changes in chromatin structure and gene expression. Multiple cofactors associate with NUP98 fusion oncoproteins to mediate transcriptional changes possibly via phase separation, in a manner likely dependent on the fusion partner. NUP98 gene fusions co-occur with a set of additional mutations, including FLT3-internal tandem duplication and other events contributing to increased proliferation. To improve the currently dire outcomes for patients with NUP98-rearranged malignancies, therapeutic strategies have been considered that target transcriptional and epigenetic machinery, cooperating alterations, and signaling or cell-cycle pathways. With the development of more faithful experimental systems and continued study, we anticipate great strides in our understanding of the molecular mechanisms and therapeutic vulnerabilities at play in NUP98-rearranged models. Taken together, these studies should lead to improved clinical outcomes for NUP98-rearranged leukemia.

Detection of recurrent, rare, and novel gene fusions in patients with acute leukemia using next-generation sequencing approaches

Identification of gene fusion is an essential part in the management of patients with acute leukemia, not only for diagnosis but also in predicting the treatment outcome and selecting appropriate treatment. Adopting next-generation sequencing (NGS) technology for identification of gene fusion in patients with acute leukemia can be a good alternative to conventional tests. In the present study, the NGS RNA fusion gene panel test was applied to diagnostic samples of patients with acute leukemia to identify fusion genes more efficiently. Among 134 patients with acute leukemia, 53 gene fusions were detected in 52 patients. In addition to the recurrent gene fusions specified in the WHO diagnostic criteria, 11 rare or novel gene fusions were identified. Of those, two were gene fusions associated with Philadelphia-like acute lymphoblastic leukemia (Ph-like ALL), two were novel gene fusions, three were gene fusions with novel partner genes, and six were rare gene fusions from previous reports. We confirmed the clinical utility of the NGS test in identifying clinically significant gene fusions such as gene fusions involving KMT2A that has a large number of partners. Notably, Ph-like ALL-associated gene fusions could be easily identified despite the wide variety of genes involved. The results from the present study may contribute toward a better understanding of the genomic landscape of acute leukemia as well as patient management.

HMGB3 silence inhibits breast cancer cell proliferation and tumor growth by interacting with hypoxia-inducible factor 1α

Background: Breast cancer is the most common malignant tumor that affects women with higher incidence. High-mobility group box 3 (HMGB3) plays critical functions in DNA repair, recombination, transcription and replication. This study aimed to investigate the effects of HMGB3 silence on mammosphere formation and tumor growth of breast cancer.

Methods: LV5-HMGB3 and LV3-siHMGB3 vectors were transfected into MCF10A, MDA-MB-231, HCC1937, ZR-75-1 and MCF7 cells. Cell counting kit-8 (CCK-8) assay was used to evaluate cell proliferation. Xenograft tumor mice model was established by injection of MDA-MB-231. qRT-PCR and western blot were used to examine the expression of Nanog, Sox2 and OCT-4. Mammosphere forming assay was employed to evaluate mammosphere formation both in vivo and in vitro. Dual luciferase assay was utilized to verify the interaction between HMGB3 and hypoxia-inducible factor 1α (HIF1α). CD44⁺/CD24⁻ was assessed with flow cytometry.

Results: HMGB3 expression was higher significantly (p<0.05) in cancer cells compared to normal cells. HMGB3 overexpression significantly (p<0.05) enhanced and HMGB3 silence reduced cell proliferative mice compared to MCF10A and MDA-MB-231, respectively. HMGB3 overexpression enhanced and HMGB3 silence inhibited mammosphere formation. HMGB3 overexpression upregulated and HMGB3 silence downregulated Nanog, SOX2 and OCT-4 genes/proteins in MCF10A and MDA-MB-231 cells, respectively. HMGB3 silence reduced CD44⁺/CD24⁻ levels in cancer cells. Silence of HMGB3 strengthened reductive effects of PTX on tumor sizes, iPSC biomarkers and mammosphere amounts in xenograft tumor mouse models. HMGB3 silence inhibited mammoshpere formation, cell proliferation and CD44⁺CD24⁻ by interacting with HIF1α.

Conclusion: HMGB3 silence could inhibit the cell proliferation in vitro and suppress tumor growth in vivo levels. The antitumor effects of HMGB3 silence were mediated by interacting with the HIF1α.

Upregulation of miR-200b Inhibits Hepatocellular Carcinoma Cell Proliferation and Migration by Targeting HMGB3 Protein

HMGB3 belongs to the high-mobility group box subfamily and has been found to be overexpressed in gastric cancer. However, the expression and the role of HMGB3 in human hepatocellular carcinoma remain unknown. Here, we report that HMGB3, which is suppressed by miR-200b, contributes to cell proliferation and migration in human hepatocellular carcinoma. After analyzing The Cancer Genome Atlas data of 371 patients with hepatocellular carcinoma, we identified HMGB3 to be upregulated in human hepatocellular carcinoma tissue. Knockdown of HMGB3 in the hepatocellular carcinoma cell line suppressed cell proliferation and migration. TargetScan analysis showed miR-200b to be a possible regulator for HMGB3. Subsequent luciferase assays indicated that HMGB3 was a direct target of miR-200b. In addition, upregulation of miR-200b inhibited hepatocellular carcinoma cell growth and migration. HMGB3 overexpression or miR-200b downregulation was associated with poor prognosis. Our findings suggest HMGB3 may serve as an important oncoprotein whose expression is negatively regulated by miR-200b in hepatocellular carcinoma.

HMGB3 promotes growth and migration in colorectal cancer by regulating WNT/β-catenin pathway

Colorectal cancer (CRC) is the third leading cause of cancer-related deaths and a major health problem. High mobility group box 3 (HMGB3), a member of the high-mobility group box (HMGB) family, was reported to be over-expressed in gastric carcinoma and bladder cancer. However, the function of HMGB3 in CRC remains unclear. Here, we found that HMGB3 was up-regulated in CRC at both mRNA and protein levels. qRT-PCR results showed that high expression of HMGB3 had positive correlation with serosal invasion, lymph metastasis, and tumor–node–metastasis (TNM) stage in CRC patient. Functional experiments showed that HMGB3 can promote CRC cells proliferation and migration in vitro. Moreover, we found HMGB3 can active WNT/β-catenin pathway to increase the expression level of c-Myc and MMP7. These results may be the reason for HMGB3 oncogene role in CRC. In summary, our data indicated that HMGB3 may serve as an oncoprotein and could be used as a potential prognostic marker in CRC.

Knockdown of High Mobility Group-Box 3 (HMGB3) Expression Inhibits Proliferation, Reduces Migration, and Affects Chemosensitivity in Gastric Cancer Cells

Background

High mobility group-box 3 (HMGB3) has been shown to affect tumor initiation and progression. This research aimed to investigate the role of HMGB3 in gastric cancer (GC) cell proliferation, migration, invasion, chemoresistance, and its potential molecular mechanisms.

Material/Methods

GC MGC803 and BGC823 cells were transfected with siRNA targeting the HMGB3 gene. The expressions of HMGB3 protein in MGC803 and BGC823 cells after transfection were detected by Western blot assays. We detected cell proliferation and cell cycle by MTT and flow cytometry assay. Cell migration and invasion were determined by wound scratch and transwell assay. MGC803 and BGC823 cells were treated with various concentrations of oxaliplatin, cisplatin, and paclitaxel. After 24 hours of drug exposure, we performed MTT assays to investigate chemoresistance in both groups. Western blot assays were used to detect related proteins expression.

Results

Silencing of HMGB3 inhibited cell proliferation and induced G0/G1 phase arrest of GC cells partly via modulating p53 and p21 pathways, and downregulating Bcl-2/Bax ratio. RNA interference of HMGB3 inhibited cell invasion and migration by downregulating MMP2 and MMP9. Silencing of HMGB3 enhanced sensitive to cisplatin and paclitaxel, and reduced sensitive to oxaliplatin.

Conclusions

These findings suggest the importance of HMGB3 in the regulation of growth, migration, and apoptosis of GC, improve our understanding of the mechanisms of GC pathogenesis, and may promote the development of novel targeted therapies.

Overexpression of HMGB3 protein promotes cell proliferation, migration and is associated with poor prognosis in urinary bladder cancer patients

Human urinary bladder cancer (UBC) is the fourth most common cancer and the eighth most common cause of cancer death in the USA. High mobility group box 3 (HMGB3), a member of a family of proteins containing one or more high mobility group DNA binding motifs, was reported to be overexpressed in a variety of human cancers. However, the expression and role of HMGB3 in human UBC remains unclear. Here, we found that UBC patients had upregulated HMGB at both mRNA and protein levels. Immunochemistry (IHC) evaluation of HMGB3 expression in 113 UBC clinical specimens showed that high expression of HMGB3 had positive correlation with UBC tumor size (P = 0.019), tumor WHO grade (P = 0.031), stage (P = 0.028), and lymph node metastasis (P = 0.017). Moreover, patients with higher HMGB3 expression showed a poorer overall survival rate than those with relatively low HMGB3 (P = 0.0079, log-rank test). Multivariate analysis revealed that HMGB3 expression is an independent prognostic marker. The UBC cancer cell proliferation and migration ability were measured by 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) and wound healing assays, respectively. RNA interference of HMGB3 in UBC cell lines inhibited cancer cell growth and migration, along with the downregulation of PCNA and MMP2 protein levels. In sum, our data suggests HMGB3 may serve as an important oncoprotein and indicate that overexpression of HMGB3 in UBC could be used as a potential prognostic marker.

HMGB1 in health and disease

Complex genetic and physiological variations as well as environmental factors that drive emergence of chromosomal instability, development of unscheduled cell death, skewed differentiation, and altered metabolism are central to the pathogenesis of human diseases and disorders. Understanding the molecular bases for these processes is important for the development of new diagnostic biomarkers, and for identifying new therapeutic targets. In 1973, a group of non-histone nuclear proteins with high electrophoretic mobility was discovered and termed high-mobility group (HMG) proteins. The HMG proteins include three superfamilies termed HMGB, HMGN, and HMGA. High-mobility group box 1 (HMGB1), the most abundant and well-studied HMG protein, senses and coordinates the cellular stress response and plays a critical role not only inside of the cell as a DNA chaperone, chromosome guardian, autophagy sustainer, and protector from apoptotic cell death, but also outside the cell as the prototypic damage associated molecular pattern molecule (DAMP). This DAMP, in conjunction with other factors, thus has cytokine, chemokine, and growth factor activity, orchestrating the inflammatory and immune response. All of these characteristics make HMGB1 a critical molecular target in multiple human diseases including infectious diseases, ischemia, immune disorders, neurodegenerative diseases, metabolic disorders, and cancer. Indeed, a number of emergent strategies have been used to inhibit HMGB1 expression, release, and activity in vitro and in vivo. These include antibodies, peptide inhibitors, RNAi, anti-coagulants, endogenous hormones, various chemical compounds, HMGB1-receptor and signaling pathway inhibition, artificial DNAs, physical strategies including vagus nerve stimulation and other surgical approaches. Future work further investigating the details of HMGB1 localization, structure, post-translational modification, and identification of additional partners will undoubtedly uncover additional secrets regarding HMGB1's multiple functions.

Upregulation of miR-513b inhibits cell proliferation, migration, and promotes apoptosis by targeting high mobility group-box 3 protein in gastric cancer

The high mobility group-box 3 (HMGB3) protein belongs to the high mobility group box (HMG-box) subfamily, and recent studies have shown that HMGB3 is an oncogene for leukemia. HMGB3 is also expressed at a high level in the progression phase of breast and gastric cancer (GC). Using bioinformatic analyses, we found that HMGB3 is a potential target for miR-513b. However, the pathophysiological role of miR-513b and its relevance to the growth and development of GC have yet to be investigated. This study focuses on whether miR-513b acts as a tumor suppressor in GC. Compared with non-malignant adjacent tissues samples, qRT-PCR data showed significant downregulation of miR-513b in 74 GC tissue samples (P < 0.01). Furthermore, western blotting revealed that HMGB3 protein was overexpressed in tumor samples relative to matched, non-malignant adjacent tissues. Western blotting and qRT-PCR results showed that high expression of HMGB3 and low expression of miR-513b were both significantly associated with primary tumors, lymph node metastases, and the clinical stage (P < 0.01). MiR-513b was shown to not only inhibit the proliferation and migration of gastric cancer cells (MKN45 and SGC7901) in the CCK-8 and transwell assays, but also to promote cell apoptosis in a flow-cytometric apoptosis assay. In western blot and luciferase assays, HMGB3 was identified as a major target of miR-513b. Moreover, we also found that the expression of HMGB3 lacking in 3' UTR could abrogate the anti-migration and pro-apoptosis function of miR-513b. These findings suggest the importance of miR-513b targeting of HMGB3 in the regulation of growth, migration and apoptosis of GC, improve our understanding of the mechanisms of GC pathogenesis, and may promote the development of novel targeted therapies.

Nucleoporin Gene Fusions and Hematopoietic Malignancies

Nuclear pore complexes (NPCs) are the sole gateways between the nucleus and the cytoplasm of eukaryotic cells and they mediate all macromolecular trafficking between these cellular compartments. Nucleocytoplasmic transport is highly selective and precisely regulated and as such an important aspect of normal cellular function. Defects in this process or in its machinery have been linked to various human diseases, including cancer. Nucleoporins, which are about 30 proteins that built up NPCs, are critical players in nucleocytoplasmic transport and have also been shown to be key players in numerous other cellular processes, such as cell cycle control and gene expression regulation. This review will focus on the three nucleoporins Nup98, Nup214, and Nup358. Common to them is their significance in nucleocytoplasmic transport, their multiple other functions, and being targets for chromosomal translocations that lead to haematopoietic malignancies, in particular acute myeloid leukaemia. The underlying molecular mechanisms of nucleoporin-associated leukaemias are only poorly understood but share some characteristics and are distinguished by their poor prognosis and therapy outcome.

Functional and molecular features of the calmodulin-interacting protein IQCG required for haematopoiesis in zebrafish

We previously reported a fusion protein NUP98-IQCG in an acute leukaemia, which functions as an aberrant regulator of transcriptional expression, yet the structure and function of IQCG have not been characterized. Here we use zebrafish to investigate the role of iqcg in haematopoietic development, and find that the numbers of haematopoietic stem cells and multilineage-differentiated cells are reduced in iqcg-deficient embryos. Mechanistically, IQCG binds to calmodulin (CaM) and acts as a molecule upstream of CaM-dependent kinase IV (CaMKIV). Crystal structures of complexes between CaM and IQ domain of IQCG reveal dual CaM-binding footprints in this motif, and provide a structural basis for a higher CaM-IQCG affinity when deprived of calcium. The results collectively allow us to understand IQCG-mediated calcium signalling in haematopoiesis, and propose a model in which IQCG stores CaM at low cytoplasmic calcium concentrations, and releases CaM to activate CaMKIV when calcium level rises.

Nucleoporins and nucleocytoplasmic transport in hematologic malignancies

Hematologic malignancies are often associated with chromosomal rearrangements that lead to the expression of chimeric fusion proteins. Rearrangements of the genes encoding two nucleoporins, NUP98 and NUP214, have been implicated in the pathogenesis of several types of hematologic malignancies, particularly acute myeloid leukemia. NUP98 rearrangements result in fusion of an N-terminal portion of NUP98 to one of numerous proteins. These rearrangements often follow treatment with topoisomerase II inhibitors and tend to occur in younger patients. They have been shown to induce leukemia in mice and to enhance proliferation and disrupt differentiation in primary human hematopoietic precursors. NUP214 has only a few fusion partners. DEK-NUP214 is the most common NUP214 fusion in AML; it tends to occur in younger patients and is usually associated with FLT3 internal tandem duplications. The leukemogenic activity of NUP214 fusions is less well characterized. Normal nucleoporins, including NUP98 and NUP214, have important functions in nucleocytoplasmic transport, transcription, and mitosis. These functions and their disruptions by oncogenic nucleoporin fusions are discussed.

Hox gene dysregulation in acute myeloid leukemia

ABSTRACT: 

In humans, class I homeobox genes (HOX genes) are distributed in four clusters. Upstream regulators include transcriptional activators and members of the CDX family of transcription factors. HOX genes encode proteins and need cofactor interactions, to increase their specificity and selectivity. HOX genes contribute to the organization and regulation of hematopoiesis by controlling the balance between proliferation and differentiation. Changes in HOX gene expression can be associated with chromosomal rearrangements generating fusion genes, such as those involving MLL and NUP98, or molecular defects, such as mutations in NPM1 and CEBPA for example. Several miRNAs are involved in the control of HOX gene expression and their expression correlates with HOX gene dysregulation. HOX genes dysregulation is a dominant mechanism of leukemic transformation. A better knowledge of their target genes and the mechanisms by which their dysregulated expression contributes to leukemogenesis could lead to the development of new drugs.

In Vivo RNAi screening identifies a leukemia-specific dependence on integrin beta 3 signaling

We used an in vivo small hairpin RNA (shRNA) screening approach to identify genes that are essential for MLL-AF9 acute myeloid leukemia (AML). We found that Integrin Beta 3 (Itgb3) is essential for murine leukemia cells in vivo and for human leukemia cells in xenotransplantation studies. In leukemia cells, Itgb3 knockdown impaired homing, downregulated LSC transcriptional programs, and induced differentiation via the intracellular kinase Syk. In contrast, loss of Itgb3 in normal hematopoietic stem and progenitor cells did not affect engraftment, reconstitution, or differentiation. Finally, using an Itgb3 knockout mouse model, we confirmed that Itgb3 is dispensable for normal hematopoiesis but is required for leukemogenesis. Our results establish the significance of the Itgb3 signaling pathway as a potential therapeutic target in AML.

Prognostic value of HMGB3 expression in patients with non-small cell lung cancer

HMGB3 overexpression has been reported in a variety of human cancers. However, the role of HMGB3 in human non-small cell lung cancer (NSCLC) remains unclear. In this study, the HMGB3 expression was examined at mRNA and protein levels by quantitative real-time reverse transcriptase-polymerase chain reaction (qRT-PCR), Western blotting, and immunohistochemistry in NSCLC tissues and adjacent non-cancerous tissues. Statistical analyses were applied to test the associations between HMGB3 expression, clinicopathologic factors, and prognosis. Western blotting and qRT-PCR showed that the expression levels of HMGB3 mRNA and protein were both significantly higher in NSCLC tissues than those in non-cancerous tissues. Immunohistochemistry analysis showed that HMGB3 expression was significantly correlated with tumor grade, tumor size, clinical stage, and lymph node metastases. The results of Kaplan-Meier analysis indicated that a high expression level of HMGB3 resulted in a significantly poor prognosis of NSCLC patients. Importantly, multivariate analysis showed that high HMGB3 expression was an independent prognostic factor for NSCLC patients. In sum, our data suggest that HMGB3 plays an important role in NSCLC progression, and that overexpression of HMGB3 in tumor tissues could be used as a potential prognostic marker for patients with NSCLC.

High mobility group-box 3 overexpression is associated with poor prognosis of resected gastric adenocarcinoma

AIM: To elucidate high mobility group-box 3 (HMGB3) protein expression in gastric adenocarcinoma, its potential prognostic relevance, and possible mechanism of action.

METHODS: Ninety-two patients with gastric adenocarcinomas surgically removed entered the study. HMGB3 expression was determined by immunohistochemistry through a tissue microarray procedure. The clinicopathologic characteristics of all patients were recorded, and regular follow-up was made for all patients. The inter-relationship of HMGB3 expression with histological and clinical factors was analyzed using nonparametric tests. Survival analysis was carried out by Kaplan-Meier (log-rank) and multivariate Cox (Forward LR) analyses between the group with overexpression of HMGB3 and the group with low or no HMGB3 expression to determine the prognosis value of HMGB3 expression on overall survival. Further, HMGB3 expression was knocked down by small hairpin RNAs (shRNAs) in the human gastric cancer cell line BGC823 to observe its influence on cell biological characteristics. The MTT method was utilized to detect gastric cancer cell proliferation changes, and cell cycle distribution was analyzed by flow cytometry.

RESULTS: Among 92 patients with gastric adenocarcinomas surgically removed in this study, high HMGB3 protein expression was detected in the gastric adenocarcinoma tissues vs peritumoral tissues (P < 0.001). Further correlation analysis with patients’ clinical and histology variables revealed that HMGB3 overexpression was obviously associated with extensive wall penetration (P = 0.005), a positive nodal status (P = 0.004), and advanced tumor-node-metastasis (TNM) stage (P = 0.001). But there was no correlation between HMGB3 overexpression and the age and gender of the patient, tumor localization or histologic grade. Statistical Kaplan-Meier survival analysis disclosed significant differences in overall survival between the HMGB3 overexpression group and the HMGB3 no or low expression group (P = 0.006). The expected overall survival time was 31.00 ± 3.773 mo (95%CI = 23.605-38.395) for patients with HMGB3 overexpression and 49.074 ± 3.648 mo (95%CI = 41.925-57.311) for patients with HMGB3 no and low-level expression. Additionally, older age (P = 0.040), extensive wall penetration (P = 0.008), positive lymph node metastasis (P = 0.005), and advanced TNM tumor stage (P = 0.007) showed negative correlation with overall survival. Multivariate Cox regression analysis indicated that HMGB3 overexpression was an independent variable with respect to age, gender, histologic grade, extent of wall penetration, lymph nodal metastasis, and TNM stage for patients with resectable gastric adenocarcinomas with poor prognosis (hazard ratio = 2.791, 95%CI = 1.233-6.319, P = 0.019). In the gene function study, after HMGB3 was knocked down in the gastric cell line BGC823 by shRNA, the cell proliferation rate was reduced at 24 h, 48 h and 72 h. Compared to BGC823 shRNA-negative control (NC) cells, the cell proliferation rate in cells that had HMGB3 shRNA transfected was significantly decreased (P < 0.01). Finally, cell cycle analysis by FACS showed that BGC823 cells that had HMGB3 knocked down were blocked in G1/G0 phase. The percentage of cells in G1/G0 phase in BGC823 cells with shRNA-NC and with shRNA-HMGB3 was 46.84% ± 1.7%, and 73.03% ± 3.51% respectively (P = 0.001), whereas G2/M cells percentage decreased from 26.51% ± 0.83% to 17.8% ± 2.26%.

CONCLUSION: HMGB3 is likely to be a useful prognostic marker involved in gastric cancer disease onset and progression by regulating the cell cycle.

Quantification of the host response proteome after mammalian reovirus T1L infection

All viruses are dependent upon host cells for replication. Infection can induce profound changes within cells, including apoptosis, morphological changes, and activation of signaling pathways. Many of these alterations have been analyzed by gene arrays to measure the cellular "transcriptome." We used SILAC (stable isotope labeling by amino acids in cell culture), combined with high-throughput 2-D HPLC/mass spectrometry, to determine relative quantitative differences in host proteins at 6 and 24 hours after infecting HEK293 cells with reovirus serotype 1 Lang (T1L). 3,076 host proteins were detected at 6 hpi, of which 132 and 68 proteins were significantly up or down regulated, respectively. 2,992 cellular proteins, of which 104 and 49 were up or down regulated, respectively, were identified at 24 hpi. IPA and DAVID analyses indicated proteins involved in cell death, cell growth factors, oxygen transport, cell structure organization and inflammatory defense response to virus were up-regulated, whereas proteins involved in apoptosis, isomerase activity, and metabolism were down-regulated. These proteins and pathways may be suitable targets for intervention to either attenuate virus infection or enhance oncolytic potential.

Functional analysis of the NUP98-CCDC28A fusion protein

BACKGROUND

The nucleoporin gene NUP98 is rearranged in more than 27 chromosomal abnormalities observed in childhood and adult, de novo and therapy-related acute leukemias of myeloid and T-lymphoid origins, resulting in the creation of fusion genes and the expression of chimeric proteins. We report here the functional analysis of the NUP98-coiled-coil domain-containing protein 28A (NUP98-CCDC28A) fusion protein, expressed as the consequence of a recurrent t(6;11)(q24.1;p15.5) translocation.

DESIGN AND METHODS

To gain insight into the function of the native CCDC28A gene, we collected information on any differential expression of CCDC28A among normal hematologic cell types and within subgroups of acute leukemia. To assess the in vivo effects of the NUP98-CCDC28A fusion, NUP98-CCDC28A or full length CCDC28A were retrovirally transduced into primary murine bone marrow cells and transduced cells were next transplanted into sub-lethally irradiated recipient mice.

RESULTS

Our in silico analyses supported a contribution of CCDC28A to discrete stages of murine hematopoietic development. They also suggested selective enrichment of CCDC28A in the French-American-British M6 class of human acute leukemia. Primary murine hematopoietic progenitor cells transduced with NUP98-CCDC28A generated a fully penetrant and transplantable myeloproliferative neoplasm-like myeloid leukemia and induced selective expansion of granulocyte/macrophage progenitors in the bone marrow of transplanted recipients, showing that NUP98-CCDC28A promotes the proliferative capacity and self-renewal potential of myeloid progenitors. In addition, the transformation mediated by NUP98-CCDC28A was not associated with deregulation of the Hoxa-Meis1 pathway, a feature shared by a diverse set of NUP98 fusions.

CONCLUSIONS

Our results demonstrate that the recurrent NUP98-CCDC28A is an oncogene that induces a rapid and transplantable myeloid neoplasm in recipient mice. They also provide additional evidence for an alternative leukemogenic mechanism for NUP98 oncogenes.

NUP98 gene fusions and hematopoietic malignancies: common themes and new biologic insights

Structural chromosomal rearrangements of the Nucleoporin 98 gene (NUP98), primarily balanced translocations and inversions, are associated with a wide array of hematopoietic malignancies. NUP98 is known to be fused to at least 28 different partner genes in patients with hematopoietic malignancies, including acute myeloid leukemia, chronic myeloid leukemia in blast crisis, myelodysplastic syndrome, acute lymphoblastic leukemia, and bilineage/biphenotypic leukemia. NUP98 gene fusions typically encode a fusion protein that retains the amino terminus of NUP98; in this context, it is important to note that several recent studies have demonstrated that the amino-terminal portion of NUP98 exhibits transcription activation potential. Approximately half of the NUP98 fusion partners encode homeodomain proteins, and at least 5 NUP98 fusions involve known histone-modifying genes. Several of the NUP98 fusions, including NUP98-homeobox (HOX)A9, NUP98-HOXD13, and NUP98-JARID1A, have been used to generate animal models of both lymphoid and myeloid malignancy; these models typically up-regulate HOXA cluster genes, including HOXA5, HOXA7, HOXA9, and HOXA10. In addition, several of the NUP98 fusion proteins have been shown to inhibit differentiation of hematopoietic precursors and to increase self-renewal of hematopoietic stem or progenitor cells, providing a potential mechanism for malignant transformation.

Amino-terminal enhancer of split (AES) interacts with the oncoprotein NUP98-HOXA9 and enhances its transforming ability

NUP98-HOXA9 is the prototype of NUP98 fusion oncoproteins that cause acute myeloid leukemia. It consists of an N-terminal FG-rich portion of the nucleoporin NUP98 fused to the homeodomain region of the homeobox protein HOXA9, and acts as an aberrant transcription factor. To identify interacting partners of NUP98-HOXA9, we used a cytoplasmic yeast two-hybrid assay to avoid the nonspecific trans-activation that would occur with the traditional yeast two-hybrid assay due to the transactivating properties of NUP98-HOXA9. We identified amino-terminal enhancer of split (AES), a transcriptional regulator of the transducin-like enhancer/Groucho family as a novel interaction partner of NUP98-HOXA9. The interaction was confirmed by in vitro pulldown and co-immunoprecipitation assays and was shown to require the FG repeat region of NUP98-HOXA9. Immunofluorescence analysis showed that AES localizes primarily to the interior of the nucleus. AES also showed a strong interaction with wild-type NUP98. AES augmented the transcriptional activity of NUP98-HOXA9. In the presence of NUP98-HOXA9, AES caused an increase in long-term proliferation of primary human CD34+ cells with a marked increase in the numbers of primitive cells. These effects of AES were not observed in the absence of NUP98-HOXA9. AES knockdown diminished the transcriptional and proliferative effects of NUP98-HOXA9. AES caused a shift away from the erythroid lineage in cells expressing NUP98-HOXA9. These data establish AES as an interacting partner of NUP98-HOXA9 and show that it cooperates with NUP98-HOXA9 in transcriptional regulation and cell transformation.