Role of SMC1A overexpression as a predictor of poor prognosis in late stage colorectal cancer

SMC2 knockdown inhibits malignant progression of lung adenocarcinoma by upregulating BTG2 expression

Lung adenocarcinoma (LUAD) is the most prevalent subtype of lung cancer worldwide. Structural maintenance of chromosomes 2 (SMC2) serves as a predictor of poor prognosis across various cancer types. This study aims to explore the role and underlying mechanisms of SMC2 in LUAD progression. The expression of SMC2 in LUAD tissues and its correlation with prognosis were analyzed by public databases. Knockdown of SMC2 was performed to assess the proliferation, migration and invasion ability of LUAD cells. Bulk RNA sequencing analysis identified enriched cellular pathways and remarkable upregulation of BTG anti-proliferation factor 2 (BTG2) expression after SMC2 knockdown in LUAD cells. Then, BTG2 was silenced to assess the malignant behavior of LUAD cells. Subcutaneous transplantation and intracranial tumor models of LUAD cells in BALB/c nude mice were established to assess the antineoplastic effect of SMC2 knockdown in vivo. Additionally, a lung metastasis model was created to evaluate the pro-metastatic effect of SMC2. Our findings indicated that SMC2 was upregulated in LUAD tissues and cell lines, with higher expression correlating with poor prognosis. SMC2 silencing suppressed the proliferation, migration and invasion ability of LUAD cells by upregulating BTG2 expression via p53 and inactivating ERK and AKT pathways. BTG2 silencing reversed the effects of SMC2 downregulation on malignant behaviors of LUAD cells and restored the phosphorylated ERK and AKT levels. Furthermore, SMC2 knockdown effectively prevented the formation of subcutaneous, intracranial and metastatic tumor in vivo, and upregulation of BTG2 expression after SMC2 knockdown was confirmed in tumor models. This study revealed that SMC2 knockdown restrained the malignant progression of LUAD through upregulation of BTG2 expression and inactivation of ERK and AKT pathways, and SMC2 could be a potential therapeutic target for LUAD treatment.

Cohesin - bridging the gap among gene transcription, genome stability, and human diseases

The intricate landscape of cellular processes governing gene transcription, chromatin organization, and genome stability is a fascinating field of study. A key player in maintaining this delicate equilibrium is the cohesin complex, a molecular machine with multifaceted roles. This review presents an in-depth exploration of these intricate connections and their significant impact on various human diseases.

Synthetic Lethality between Cohesin and WNT Signaling Pathways in Diverse Cancer Contexts

Cohesin is a highly conserved ring-shaped complex involved in topologically embracing chromatids, gene expression regulation, genome compartmentalization, and genome stability maintenance. Genomic analyses have detected mutations in the cohesin complex in a wide array of human tumors. These findings have led to increased interest in cohesin as a potential target in cancer therapy. Synthetic lethality has been suggested as an approach to exploit genetic differences in cancer cells to influence their selective killing. In this study, we show that mutations in ESCO1, NIPBL, PDS5B, RAD21, SMC1A, SMC3, STAG2, and WAPL genes are synthetically lethal with stimulation of WNT signaling obtained following LY2090314 treatment, a GSK3 inhibitor, in several cancer cell lines. Moreover, treatment led to the stabilization of β-catenin and affected the expression of c-MYC, probably due to the occupancy decrease in cohesin at the c-MYC promoter. Finally, LY2090314 caused gene expression dysregulation mainly involving pathways related to transcription regulation, cell proliferation, and chromatin remodeling. For the first time, our work provides the underlying molecular basis for synthetic lethality due to cohesin mutations and suggests that targeting the WNT may be a promising therapeutic approach for tumors carrying mutated cohesin.

The synergism of SMC1A cohesin gene silencing and bevacizumab against colorectal cancer

BACKGROUND

SMC1A is a subunit of the cohesin complex that participates in many DNA- and chromosome-related biological processes. Previous studies have established that SMC1A is involved in cancer development and in particular, is overexpressed in chromosomally unstable human colorectal cancer (CRC). This study aimed to investigate whether SMC1A could serve as a therapeutic target for CRC.

METHODS

At first, we studied the effects of either SMC1A overexpression or knockdown in vitro. Next, the outcome of SMC1A knocking down (alone or in combination with bevacizumab, a monoclonal antibody against vascular endothelial growth factor) was analyzed in vivo.

RESULTS

We found that SMC1A knockdown affects cell proliferation and reduces the ability to grow in anchorage-independent manner. Next, we demonstrated that the silencing of SMC1A and the combo treatment were effective in increasing overall survival in a xenograft mouse model. Functional analyses indicated that both treatments lead to atypical mitotic figures and gene expression dysregulation. Differentially expressed genes were implicated in several pathways including gene transcription regulation, cellular proliferation, and other transformation-associated processes.

CONCLUSIONS

These results indicate that SMC1A silencing, in combination with bevacizumab, can represent a promising therapeutic strategy for human CRC.

SMC1A facilitates gastric cancer cell proliferation, migration, and invasion via promoting SNAIL activated EMT

BACKGROUND

Structural maintenance of chromosomes protein 1 A (SMC1A) is a crucial subunit of the cohesion protein complex and plays a vital role in cell cycle regulation, genomic stability maintenance, chromosome dynamics. Recent studies demonstrated that SMC1A participates in tumorigenesis. This reseach aims to explore the role and the underlying mechanisms of SMC1A in gastric cancer (GC).

MATERIALS AND METHODS

RT-qPCR and western blot were used to examine the expression levels of SMC1A in GC tissues and cell lines. The role of SMC1A on GC cell proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) were analyzed. Furthermore,the mechanism of SMC1A action was investigated.

RESULTS

SMC1A was highly expressed in GC tissues and cell lines. The high expression of SMC1A indicated the poor overall survival of GC patients from Kaplan-Meier Plotter. Enhancing the expression of SMC1A in AGS cells remarkably promoted cell proliferation in vitro and in vivo, migration and invasion, Conversely, knockdown of SMC1A in HGC27 cells inhibited cell proliferation, migration and invasion. Moreover, it's observed that SMC1A promoted EMT and malignant cell behaviors via regulating SNAIL.

CONCLUSION

Our study revealed that SMC1A promotes EMT process by upregulating SNAIL, which contributes to gastric cancer cell proliferation, migration and invasion. Therefore, targeting SMC1A may be a potential strategy to improve GC therapy.

MiR-520d-3p suppresses the proliferation and epithelial-mesenchymal transition of cervical cancer cells by targeting ZFP36L2

MiR-520d-3p has recently been reported to have anti-tumor function in several cancers, including glioma and gastric cancer. However, the biological function and its mechanism of action remain unclear in cervical cancer (CC). In this study, we observed that miR-520d-3p expression was lowly expressed in CC specimens compared with adjacent normal specimens using reverse transcription quantitative PCR. Moreover, low miR-520d-3p expression was correlated with FIGO stage and lymph node metastasis by Chi-square test. Functionally, overexpression of miR-520d-3p suppressed the proliferation and migration and invasion of two CC cell lines (HeLa and SiHa) using CCK-8 assay and wound healing assay. After target prediction, luciferase reporter assay showed that zinc finger protein 36 ring finger protein-like 2 (ZFP36L2) was a direct target of miR-520d-3p in CC cells. The expression levels of ZFP36L2 at protein and mRNA were significantly increased in CC tissues compared with adjacent tissues. The expression of ZFP36L2 was negatively correlated with miR-520d-3p in the patients with CC. Importantly, ZFP36L2 overexpression abolished the effects of miR-520d-3p on cell proliferation, migration and EMT process in CC cells. In conclusion, our findings indicate that targeting miR-520d-3p/ZFP36L2 axis might be a promising therapeutic target for CC treatment.

Expression profile and prognostic values of SMC family members in HCC

OBJECTIVE

The structural maintenance of chromosome (SMC) gene family, including 6 proteins, is involved in a wide range of biological functions in different human cancers. Nevertheless, there is little research on the expression patterns, potential functions and prognostic value of SMC genes in hepatocellular carcinoma (HCC). Based on publicly available databases and integrative bioinformatics analysis, we tried to determine the value of SMC gene expression in predicting the risk of developing HCC.

METHODS

The expression and copy number variations data of SMC family members were obtained from TCGA (The Cancer Genome Atlas). We identified the prognostic values of SMC family members and their clinical features. GSEA (Gene Set Enrichment Analysis) was conducted to detect the mechanism underlying the involvement of SMC family members in liver cancer. We used Tumor Immune Estimation Resource database to explore the associations between TIICs (Tumor Immune Infiltrating Cells) and the SMC family members.

RESULTS

Our analysis proved that downregulation of SMC family members was common modification in HCC patients. In HCC, the expression of SMC1A, SMC2, SMC3, SMC4, SMC6 were upregulated. Upregulation of SMC2, SMC3, and SMC4, along with the clinical stage of HCC, were associated with a poor prognosis according to the results of univariate and multivariate Cox proportional hazards regression analysis. SMC2, SMC3, and SMC4 are also related to tumor purity and immune infiltration levels of HCC. The GSEA results proved that SMC family members take part in numerous biological processes underlying tumorigenesis.

CONCLUSION

In this study, we comprehensively analyzed the expression of SMC family members in patients with HCC. This can provide insights for further investigation of the SMC members as potential therapeutic targets in HCC and suggest that the use of SMC inhibitor targeting SMC2, SMC3, and SMC4 can be a practical strategy for the therapy of HCC.

CCL18 promotes breast cancer progression by exosomal miR-760 activation of ARF6/Src/PI3K/Akt pathway

The small GTPase ADP-ribosylation factor 6 (ARF6) mediates chemokine (C-C motif) ligand 18 (CCL18)-induced activation of breast cancer (BC) metastasis through its downstream effector AMAP1. However, the molecular mechanisms underlying CCL18 up-regulating ARF6 remain largely unclear. Here, microRNAs (miRNAs) that target ARF6 were predicted and selected in high metastatic BC cells treated with CCL18. Next, we assessed the role of exosomal miR-760 in vitro and in vivo. We further analyzed the expression of ARF6, AMAP1, and phosphorylated (p)-AMAP1 in tumor and adjacent normal tissues. We first observed that CCL18 increased the expression of ARF6 and p-AMAP1 and activated the Src/phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway. ARF6 knockdown significantly impaired CCL18-induced malignant cellular behaviors and the Src/PI3K/Akt signaling pathway. Next, ARF6 was confirmed as a target gene of miR-760 in exosomes derived from CCL18-stimulated high metastatic BC cells. Moreover, recipient MCF-7 cells could effectively uptake these miR-760-rich exosomes that significantly promoted proliferation, tumor growth in vivo, migration, invasion, and chemoresistance by activating ARF6-mediated Src/PI3K/Akt signaling and the epithelial-mesenchymal transition (EMT) pathway. Together, our results support that exosomal miR-760 secreted by CCL18-stimulated high metastatic BC cells promoted the malignant behaviors in low metastatic BC cells by up-regulating the ARF6-mediated Src/PI3K/Akt signaling pathway.

The multifaceted roles of cohesin in cancer

The cohesin complex controls faithful chromosome segregation by pairing sister chromatids after DNA replication until mitosis. In addition, it is crucial for hierarchal three-dimensional organization of the genome, transcription regulation and maintaining DNA integrity. The core complex subunits SMC1A, SMC3, STAG1/2, and RAD21 as well as its modulators, have been found to be recurrently mutated in human cancers. The mechanisms by which cohesin mutations trigger cancer development and disease progression are still poorly understood. Since cohesin is involved in a range of chromosome-related processes, the outcome of cohesin mutations in cancer is complex. Herein, we discuss recent discoveries regarding cohesin that provide new insight into its role in tumorigenesis.

The deacetylation-phosphorylation regulation of SIRT2-SMC1A axis as a mechanism of antimitotic catastrophe in early tumorigenesis

Improper distribution of chromosomes during mitosis can contribute to malignant transformation. Higher eukaryotes have evolved a mitotic catastrophe mechanism for eliminating mitosis-incompetent cells; however, the signaling cascade and its epigenetic regulation are poorly understood. Our analyses of human cancerous tissue revealed that the NAD-dependent deacetylase SIRT2 is up-regulated in early-stage carcinomas of various organs. Mass spectrometry analysis revealed that SIRT2 interacts with and deacetylates the structural maintenance of chromosomes protein 1 (SMC1A), which then promotes SMC1A phosphorylation to properly drive mitosis. We have further demonstrated that inhibition of SIRT2 activity or continuously increasing SMC1A-K579 acetylation causes abnormal chromosome segregation, which, in turn, induces mitotic catastrophe in cancer cells and enhances their vulnerability to chemotherapeutic agents. These findings suggest that regulation of the SIRT2-SMC1A axis through deacetylation-phosphorylation permits escape from mitotic catastrophe, thus allowing early precursor lesions to overcome oncogenic stress.

Prognostic relevance of SMC family gene expression in human sarcoma

Objective: To explore the prognostic value of the expression of genes encoding structural maintenance of chromosomes (SMCs) in human sarcoma.

Results: We found that the levels of SMC1A, SMC2, SMC3, SMC4, SMC5 and SMC6 mRNA were all higher in most tumors compared to normal tissues, and especially in sarcoma. According to the Cancer Cell Line Encyclopedia (CCLE), SMC1A, SMC2, SMC3, SMC4, SMC5 and SMC6 are also highly expressed in sarcoma cell lines. Results of Gene Expression Profiling Interactive Analysis (GEPIA) indicated that high expression of SMC1A was significantly related to poor overall survival (OS) (p<0.05) and disease-free survival (DFS) in sarcoma (p<0.05). Additionally, strong expression of SMC2 was significantly related to poor OS in sarcoma (p<0.05). In contrast, SMC3, SMC4, SMC5, and SMC6 expression had no significant impact on OS or DFS in sarcoma.

Conclusions: Expression of SMC family members is significantly different in sarcoma relative to normal tissues, and SMC1A and SMC2 may be useful as prognostic biomarkers.

Methods: We performed a detailed comparison of cancer and normal tissues regarding the expression levels of mRNA for SMC family members in various cancers including sarcoma through ONCOMINE and GEPIA (Gene Expression Profile Interactive Analysis) databases.

The multiple facets of the SMC1A gene

Structural Maintenance of Chromosomes (SMCs) are part of a large family of ring complexes that participates in a number of DNA transactions. Among SMCs, SMC1A gene is unique. It encodes a subunit of the cohesin-core complex that tethers sister chromatids together to ensure correct chromosome segregation in both mitosis and meiosis. As a member of the cohesin ring, SMC1A takes part in gene transcription regulation and genome organization; and it participates in the DNA Damage Repair (DDR) pathway, being phosphorylated by Ataxia Telangiectasia Mutated (ATM) and Ataxia Telangiectasia and Rad3 Related (ATR) threonine/serine kinases. It is also a component of the Recombination protein complex (RC-1) involved in DNA repair by recombination. SMC1A pathogenic variants have been described in Cornelia de Lange syndrome (CdLS), a human rare disease, and recently SMC1A variants have been associated with epilepsy or resembling Rett syndrome phenotype. Finally, SMC1A variants have been identified in several human cancers. In this review, our current knowledge of the SMC1A gene has been summarized.

Comparison of signaling profiles in the low dose range following low and high LET radiation

During space travel astronauts will be exposed to a very low, mixed field of radiation containing different high LET particles of varying energies, over an extended period. Thus, defining how human cells respond to these complex low dose exposures is important in ascertaining risk. In the current study, we have chosen to investigate how low doses of three different ion's at various energies uniquely change the kinetics of three different phospho-proteins. A normal hTERT immortalized fibroblast cell line, 82-6, was exposed to a range of lower doses (0.05-0.5 Gy) of radiation of different qualities and energies (Si 1000 MeV/u, Si 300 MeV/u, Si 173 MeV/u, Si 93 MeV/u, Fe 1000 MeV/u, Fe 600 MeV/u, Fe 300 MeV/u, Ti 300 MeV/u, Ti 326 MeV/u, Ti 386 MeV/u), covering a wide span of LET's. Exposed samples were analyzed for the average intensity of signal as a fold over the geometric mean level of the sham controls. Three phospho-proteins known to localize to DNA DSBs following radiation (γH2AX, pATF2, pSMC1) were studied. The kinetics of their response was quantified by flow cytometery at 2 and 24 h post exposure. These studies reveal unique kinetic patterns based on the ion, energy, fluence and time following exposure. In addition, γH2AX phosphorylation patterns are uniquely different from phospho-proteins known to be primarily phosphorylated by ATM. This latter finding suggests that the activating kinase(s), or the phosphatases deactivating these proteins, exhibit differences in their response to various radiation qualities and/ or doses of exposure. Further studies will be needed to better define what the differing kinetics for the kinases activated by the unique radiation qualities plays in the biological effectiveness of the particle.

Knockdown of lncRNA TUG1 Enhances Radiosensitivity of Prostate Cancer via the TUG1/miR-139-5p/SMC1A Axis

Background

Prostate cancer (PCa) is a common malignant tumor of the urinary system in males. LncRNA taurine-upregulated gene 1 (TUG1) has been verified to play a crucial role in progression and prognosis of PCa. However, the functional mechanism of TUG1 remains unclear with radiosensitivity of PCa.

Methods

Quantitative real-time PCR (qRT-PCR) was conducted to measure the transcription levels of genes. 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide (MTT) assay and flow cytometry analysis were employed to assess cell proliferation and apoptosis, respectively. Moreover, colony formation assay was used to measure colony survival. Western blot was performed to detect the relative proteins expression. The interaction among variables was predicted by online tool starbase, and then confirmed using the dual luciferase reporter assay. A xenograft mouse model was constructed to investigate the effect of TUG1 on tumor growth in vivo.

Results

The levels of lncRNA TUG1 and SMC1A were remarkably increased, while miR-139-5p was downregulated in PCa. Patients with high expression of TUG1 showed a lower survival rate and poor prognosis. Knockdown of TUG1 inhibited PCa cell proliferation and colony survival fraction, and promoted apoptosis. Downregulation of miR-139-5p reversed the effects of TUG1 deletion on proliferation, apoptosis and colony survival fraction in PCa cells treated with 4 Gy of X-ray radiation. Moreover, TUG1 sponged miR-139-5p to regulate SMC1A expression. SMC1A deletion blocked the effects of TUG1 on the progression of PCa cells treated with 4 Gy of X-ray radiation. The tumor volume and weight were illustriously reduced with radiation and TUG1 silencing in xenograft model.

Conclusion

Knockdown of lncRNA TUG1 enhanced radiosensitivity in PCa via the TUG1/miR-139-5p/SMC1A axis. It may become a promising target for PCa treatment.

miRNA-mRNA Profiling Reveals Prognostic Impact of SMC1A Expression in Acute Myeloid Leukemia

Acute myeloid leukemia (AML) with NPM1 mutation is a disease driving genetic alteration with good prognosis. Although it has been suggested that NPM1 mutation induces chemosensitivity in leukemic cells, the underlying cause for the better survival of NPM1 mutated patients is still not clear. Mutant NPM1 AML has a unique microRNA and their target gene (mRNA) signature compared to wild-type NPM1. Dynamic regulation of miRNA–mRNA has been reported to influence the prognostic outcome. In the present study, in silico expression data of miRNA and mRNA in AML patients was retrieved from genome data commons, and differentially expressed miRNA and mRNA among NPM1 mutated (n = 21) and NPM1 wild-type (n = 162) cases were identified to establish a dynamic association at the molecular level. In vitro experiments using high-throughput RNA sequencing were performed on human AML cells carrying NPM1 mutated and wild-type allele. The comparison of in vitro transcriptomics data with in silico miRNA–mRNA expression network data revealed downregulation of SMC1A. On establishing miRNA–mRNA interactive pairs, it has been observed that hsa-mir-215-5p (logFC: 0.957; p = 0.0189) is involved in the downregulation of SMC1A (logFC: –0.481; p = 0.0464) in NPM1 mutated AML. We demonstrated that transient expression of NPM1 mutation upregulates miR-215-5p, which results in downregulation of SMC1A. We have also shown using a rescue experiment that neutralizing miR-215-5p reverses the effect of NPM1 mutation on SMC1A. Using the leukemic blasts from AML patients, we observed higher expression of miR-215-5p and lower expression of SMC1A in NPM1 mutated patients compared to wild-type cases. The overall survival of AML patients was significantly inferior in SMC1A high expressers compared to low expressers (20.3% vs. 58.5%, p = 0.018). The data suggest that dynamic miR-215-SMC1A regulation is potentially modulated by NPM1 mutation, which might serve as an explanation for the better outcome in NPM1 mutated AML.

Bloom Syndrome Protein Activates AKT and PRAS40 in Prostate Cancer Cells

Purpose

Prostate cancer (PC) is a common malignant tumor and a leading cause of cancer-related death in men worldwide. In order to design new therapeutic interventions for PC, an understanding of the molecular events underlying PC tumorigenesis is required. Bloom syndrome protein (BLM) is a RecQ-like helicase, which helps maintain genetic stability. BLM dysfunction has been implicated in tumor development, most recently during PC tumorigenesis. However, the molecular basis for BLM-induced PC progression remains poorly characterized. In this study, we investigated whether BLM modulates the phosphorylation of an array of prooncogenic signaling pathways to promote PC progression.

Methods

We analyzed differentially expressed proteins (DEPs) using iTRAQ technology. Site-directed knockout of BLM in PC-3 prostate cancer cells was performed using CRISPR/Cas9-mediated homologous recombination gene editing to confirm the effects of BLM on DEPs. PathScan® Antibody Array Kits were used to analyze the phosphorylation of nodal proteins in PC tissue. Immunohistochemistry and automated western blot (WES) analyses were used to validate these findings.

Results

We found that silencing BLM in PC-3 cells significantly reduced their proliferative capacity. In addition, BLM downregulation significantly reduced levels of phosphorylated protein kinase B (AKT (Ser473)) and proline-rich AKT substrate of 40 kDa (PRAS40 (Thr246)), and this was accompanied by enhanced ROS (reactive oxygen species) levels. In addition, we found that AKT and PRAS40 inhibition reduced BLM, increased ROS levels, and induced PC cell apoptosis.

Conclusions

We demonstrated that BLM activates AKT and PRAS40 to promote PC cell proliferation and survival. We further propose that ROS act in concert with BLM to facilitate PC oncogenesis, potentially via further enhancing AKT signaling and downregulating PTEN expression. Importantly, inhibiting the BLM-AKT-PRAS40 axis induced PC cell apoptosis. Thus, we highlight new avenues for novel anti-PC treatments.

Overexpression of the cohesin-core subunit SMC1A contributes to colorectal cancer development

BACKGROUND

Cancer cells are characterized by chromosomal instability (CIN) and it is thought that errors in pathways involved in faithful chromosome segregation play a pivotal role in the genesis of CIN. Cohesin forms a large protein ring that binds DNA strands by encircling them. In addition to this central role in chromosome segregation, cohesin is also needed for DNA repair, gene transcription regulation and chromatin architecture. Though mutations in both cohesin and cohesin-regulator genes have been identified in many human cancers, the contribution of cohesin to cancer development is still under debate.

METHODS

Normal mucosa, early adenoma, and carcinoma samples deriving from 16 subjects affected by colorectal cancer (CRC) were analyzed by OncoScan for scoring both chromosome gains and losses (CNVs) and loss of heterozygosity (LOH). Then the expression of SMC1A was analyzed by immunochemistry in 66 subjects affected by CRC. The effects of SMC1A overexpression and mutated SMC1A were analyzed in vivo using immunocompromised mouse models. Finally, we measured global gene expression profiles in induced-tumors by RNA-seq.

RESULTS

Here we showed that SMC1A cohesin core gene was present as extra-copies, mutated, and overexpressed in human colorectal carcinomas. We then demonstrated that cohesin overexpression led to the development of aggressive cancers in immunocompromised mice through gene expression dysregulation.

CONCLUSION

Collectively, these results support a role of defective cohesin in the development of human colorectal cancer.

Silencing of COPB2 inhibits the proliferation of gastric cancer cells and induces apoptosis via suppression of the RTK signaling pathway

Emerging studies have reported that coatomer protein complex subunit β2 (COPB2) is overexpressed in several types of malignant tumor; however, to the best of our knowledge, no studies regarding COPB2 in gastric cancer have been published thus far. Therefore, the present study aimed to determine the significance and function of COPB2 in gastric cancer. COPB2 expression in gastric cancer cell lines was measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR) analysis. In addition, lentivirus-short hairpin RNA (shRNA) COPB2 (Lv-shCOPB2) was generated and used to infect BGC-823 cells to analyze the effects of COPB2 on the cancerous phenotype. The effects of shRNA-mediated COPB2 knockdown on cell proliferation were detected using MTT, 5-bromo-2-deoxyuridine and colony formation assays. In addition, the effects of COPB2 knockdown on apoptosis were analyzed by flow cytometry. Nude mice and fluorescence imaging were used to characterize the regulation of tumor growth in vivo, and qPCR and immunohistochemistry were subsequently conducted to analyze COPB2 expression in xenograft tumor tissues. Furthermore, a receptor tyrosine kinase (RTK) signaling pathway antibody array was used to explore the relevant molecular mechanisms underlying the effects of COPB2 knockdown. The results revealed that COPB2 mRNA was abundantly overexpressed in gastric cancer cell lines, whereas knockdown of COPB2 significantly inhibited cell growth and colony formation ability, and led to increased cell apoptosis in vitro. The tumorigenicity assay revealed that knockdown of COPB2 reduced tumor growth in nude mice, and fluorescence imaging indicated that the total radiant efficiency of mice in the Lv-shCOPB2-infected group was markedly reduced compared with the mice in the Lv-shRNA control-infected group in vivo. The antibody array assay revealed that the levels of phosphorylation in 23 target RTKs were significantly reduced: In conclusion, COPB2 was highly expressed in gastric cancer cell lines, and knockdown suppressed colony formation and promoted cell apoptosis via inhibiting the RTK signaling and its downstream signaling cascade molecules. Therefore, COPB2 may present a valuable target for gene silencing strategy in gastric cancer.

SMC1A is associated with radioresistance in prostate cancer and acts by regulating epithelial-mesenchymal transition and cancer stem-like properties

Prostate cancer is one of the most commonly diagnosed cancers and a pressing health challenge in men worldwide. Radiation therapy (RT) is widely considered a standard therapy for advanced as well as localized prostate cancer. Although this primary therapy is associated with high cancer control rates, up to one-third of patients undergoing radiation therapy becomes radio-resistant and/or has tumor-relapse/recurrence. Therefore, focus on new molecular targets and pathways is essential to develop novel radio-sensitizing agents for the effective and safe treatment of prostate cancer. Here, we describe functional studies that were performed to investigate the role of structural maintenance of chromosome-1 (SMC1A) in radioresistance of metastatic prostate cancer cells. Short hairpin RNA (shRNA) was used to suppress SMC1A in metastatic castration-resistant prostate cancer cells, DU145 and PC3. Clonogenic survival assays, Western blot, RT-PCR, and γ-H2AX staining were used to assess the effect of SMC1A knockdown on radiation sensitivity of these prostate cancer cells. We demonstrate that SMC1A is overexpressed in human prostate tumors compared to the normal adjacent tissue. SMC1A knockdown limits the clonogenic potential, epithelial-mesenchymal transition (EMT), and cancer stem-like cell (CSC) properties of DU145 and PC3 cells and enhanced efficacy of RT in these cells. Targeted inhibition of SMC1A not only plays a critical role in overcoming radio-resistance in prostate cancer cells, but also suppresses self-renewal and the tumor-propagating potential of x-irradiated cancer cells. We propose that SMC1A could be a potential molecular target for the development of novel radio-sensitizing therapeutic agents for management of radio-resistant metastatic prostate cancer.

Long noncoding RNA NEAT1 modulates cell proliferation and apoptosis by regulating miR-23a-3p/SMC1A in acute myeloid leukemia

The aim of this study was to determine the function of the NEAT1/miR-23a-3p/SMC1A axis in cell proliferation and apoptosis in acute myeloid leukemia (AML). Microarray analysis was used to screen differentially expressed lncRNAs/miRNAs/mRNAs in primary AML cells. The expression of nuclear paraspeckle assembly transcript 1 (NEAT1), miR-23a-3p, and structural maintenance of chromosome 1 alpha (SMC1A) in primary AML cells and THP-1 cells were measured by quantitative real-time polymerase chain reaction (qRT-PCR). A Cell Counting Kit-8 (CCK-8) assay was used to analyze proliferation. Cell cycle progression and apoptosis were examined by flow cytometry. RNA immunoprecipitation (RIP) and dual-luciferase assays were performed to determine the correlation between miR-23a-3p and NEAT1 or SMC1A. The qRT-PCR illustrated that NEAT1 and SMC1A expression was decreased but that miR-23a-3p expression was increased in primary AML cells and THP-1 cells compared with that in normal cells. The RIP assay and dual-luciferase assay revealed the targeting relationship between miR-23a-3p and NEAT1 or SMC1A. The CCK-8 assay showed that the overexpression of NEAT1 and SMC1A or repression of miR-23a-3p inhibited cell proliferation. Flow cytometry showed that the upregulation of NEAT1 and SMC1A or repression of miR-23a-3p promoted apoptosis and affected the cell cycle. NEAT1 repressed the expression of miR-23a-3p, and therefore promoted SMC1A, which in turn suppressed myeloid leukemia cell proliferation and enhanced apoptosis.

Phosphorylation of SMC1A promotes hepatocellular carcinoma cell proliferation and migration

Structural maintenance of chromosomes protein 1A (SMC1A) has been implicated in the development of a variety of cancer types. However, its role in hepatocellular carcinoma remains unknown. In this study, we found that phosphorylated SMC1A was highly expressed in HepG2 and Bel7402 cells when compared with other cancer cell lines. Furthermore, SMC1A knockdown dramatically reduced HepG2 and Bel7402 cell proliferation and migration. Re-expressing phosphomimetic mutants S957DS966D significantly enhanced the proliferation and migration of SMC1A knockdown HepG2 and Bel7402 cells. In addition, phosphorylated SMC1A promotes hepatocellular carcinoma cells growth in vivo. Importantly, the expression of phosphorylated SMC1A was significantly higher in human hepatocellular carcinomacells when compared to peri-tumor benign hepatocytes, and its overexpression was significantly associated with worse prognostic outcomes. These observations suggest that phosphorylation of SMC1A is a vital event in tumorigenesis and disease progression in hepatocellular carcinoma thus necessitating further investigation.

Actin Filament-Associated Protein 1-Like 1 Mediates Proliferation and Survival in Non-Small Cell Lung Cancer Cells

BACKGROUND The actin filament-associated protein (AFAP) family consists of 3 novel adaptor proteins: AFAP1, AFAP1L1, and AFAP1L2/XB130. Although evidence shows that AFAP1 and AFAP1L2 play an oncogenic role, the effect of AFAP1L1 on tumor cell behavior has not been fully elucidated, and it remains unknown whether AFAP1L1 could be a prognostic marker and/or therapeutic target of lung cancer. MATERIAL AND METHODS Human A549 non-small cell lung cancer (NSCLC) cells were used in this study. AFAP1L1 gene was knocked down by AFAP1L1 short hairpin RNA (shRNA) transfection. Cell proliferation was analyzed using Celigo image cytometry and MTT [3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide] assay, cell cycle progression was assessed with flow cytometry, and cell apoptosis was determined by flow cytometry after annexin-n staining. The PathScan intracellular signaling array was used to investigate cancer-related signaling proteins influenced by knocking down AFAP1L1 in A549. RESULTS AFAP1L1 gene expression was successfully inhibited by the AFAP1L1-shRNA transfection. Cell proliferation was inhibited and cell proportions in G1 and G2/M phases were increased, and cell apoptosis was increased in the AFAP1L1-shRNA transfected cells as compared with negative control shRNA transfected cells. Using the PathScan intracellular signaling array, we found that downregulation of AFAP1L1 significantly activated P38 and caspase 3, and inhibited PRAS40 activation. CONCLUSIONS Our data show that AFAP1L1 promotes cell proliferation, accelerates cell cycle progression, and prevents cell apoptosis in lung cancer cells. Therefore, AFAP1L1 might play an oncogenic role in NSCLC.

Structural Maintenance of Chromosomes protein 1: Role in Genome Stability and Tumorigenesis

SMC1 (Structural Maintenance of Chromosomes protein 1), well known as one of the SMC superfamily members, has been explored to function in many activities including chromosome dynamics, cell cycle checkpoint, DNA damage repair and genome stability. Upon being properly assembled as part of cohesin, SMC1 can be phosphorylated by ATM and mediate downstream DNA damage repair after ionizing irradiation. Abnormal gene expression or mutation of SMC1 can cause defect in the DNA damage repair pathway, which has been strongly associated with tumorigenesis. Here we focus to discuss SMC1's role in genome stability maintenance and tumorigenesis. Deciphering the underlying molecular mechanism can provide insight into novel strategies for cancer treatment.

Synaptotagmin-7 is overexpressed in hepatocellular carcinoma and regulates hepatocellular carcinoma cell proliferation via Chk1-p53 signaling

Background

Synaptotagmin-7 (Syt-7) is a member of the synaptotagmin (Syt) family, which plays an important role in many physiological and pathological processes. However, to the best of our knowledge, there is no study describing its function in tumors, particularly in hepatocellular carcinoma (HCC). Therefore, in this study, we examined the role of Syt-7 in HCC and attempted to elucidate its underlying mechanism.

Materials and methods

We examined the expression levels of Syt-7 in HCC cell lines and normal hepatocytes by real-time quantitative polymerase chain reaction analysis. The effects of Syt-7 knockdown on in vitro cell growth were assessed by Celigo image cytometry, MTT assay, colony formation assay, and cell cycle analysis. In vivo tumorigenesis was evaluated using a nude mouse model. The underlying molecular mechanism was evaluated using a PathScan Stress Signaling Antibody Array.

Results

Syt-7 mRNA levels were highly expressed in Huh-7 and Hep3B cells; moderately expressed in SMMC-7721, HepG2, and BEL-7402 cells; and lowly expressed in normal hepatocytes L-O2. Functional experiments demonstrated that Syt-7 knockdown significantly suppressed cell proliferation and induced cell cycle arrest by increasing phosphorylation of Chk1 and p53. Furthermore, Syt-7 knockdown remarkably reduced the growth of xenograft tumors in mice.

Conclusion

The results of this study suggest that Syt-7 plays a vital role in tumorigenesis and in the development of HCC. Syt-7 can be used as a new diagnostic and therapeutic target in HCC.

Two-step ATP-driven opening of cohesin head

The cohesin ring is a protein complex composed of four core subunits: Smc1A, Smc3, Rad21 and Stag1/2. It is involved in chromosome segregation, DNA repair, chromatin organization and transcription regulation. Opening of the ring occurs at the "head" structure, formed of the ATPase domains of Smc1A and Smc3 and Rad21. We investigate the mechanisms of the cohesin ring opening using techniques of free molecular dynamics (MD), steered MD and quantum mechanics/molecular mechanics MD (QM/MM MD). The study allows the thorough analysis of the opening events at the atomic scale: i) ATP hydrolysis at the Smc1A site, evaluating the role of the carboxy-terminal domain of Rad21 in the process; ii) the activation of the Smc3 site potentially mediated by the movement of specific amino acids; and iii) opening of the head domains after the two ATP hydrolysis events. Our study suggests that the cohesin ring opening is triggered by a sequential activation of the ATP sites in which ATP hydrolysis at the Smc1A site induces ATPase activity at the Smc3 site. Our analysis also provides an explanation for the effect of pathogenic variants related to cohesinopathies and cancer.

Cohesin Mutations in Myeloid Malignancies

Acute Myeloid Leukemia (AML) is a hematologic malignancy with a poor prognosis. Recent genome-wide sequencing studies have identified frequent mutations in genes encoding members of the cohesin complex. Mutations in cohesin contribute to myeloid malignancies by conferring enhanced self-renewal of hematopoietic stem and progenitor cells but the mechanisms behind this phenotype have not been fully elucidated. Of note, cohesin mutations are highly prevalent in acute megakaryocytic leukemia associated with Down syndrome (DS-AMKL), where they occur in over half of patients. Evidence suggests that cohesin mutations alter gene expression through changes in chromatin accessibility and/or aberrant targeting of epigenetic complexes. In this review we discuss the pathogenic mechanisms by which cohesin mutations contribute to myeloid malignancies.

Identification of the Key Genes and Pathways in Esophageal Carcinoma

Objective. Esophageal carcinoma (EC) is a frequently common malignancy of gastrointestinal cancer in the world. This study aims to screen key genes and pathways in EC and elucidate the mechanism of it. Methods. 5 microarray datasets of EC were downloaded from Gene Expression Omnibus. Differentially expressed genes (DEGs) were screened by bioinformatics analysis. Gene Ontology (GO) enrichment, Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment, and protein-protein interaction (PPI) network construction were performed to obtain the biological roles of DEGs in EC. Quantitative real-time polymerase chain reaction (qRT-PCR) was used to verify the expression level of DEGs in EC. Results. A total of 1955 genes were filtered as DEGs in EC. The upregulated genes were significantly enriched in cell cycle and the downregulated genes significantly enriched in Endocytosis. PPI network displayed CDK4 and CCT3 were hub proteins in the network. The expression level of 8 dysregulated DEGs including CDK4, CCT3, THSD4, SIM2, MYBL2, CENPF, CDCA3, and CDKN3 was validated in EC compared to adjacent nontumor tissues and the results were matched with the microarray analysis. Conclusion. The significantly DEGs including CDK4, CCT3, THSD4, and SIM2 may play key roles in tumorigenesis and development of EC involved in cell cycle and Endocytosis.

SMC1A promotes growth and migration of prostate cancer in vitro and in vivo

Structural maintenance of chromosome 1 alpha (SMC1A) gene has been reported to be related to tumor development in some types of human cancers. However, the misregulation of SMC1A and its functions in castration-resistant prostate cancer (CRPC) have not been well understood. In the present study, we found that SMC1A was elevated in androgen-independent PCa cell lines PC-3 and DU-145 compared to androgen sensitive LNCap and 22RV1 cells by qPCR and western blot assay. Knockdown of SMC1A inhibited cell growth, colony formation and cell migration abilities of PC-3 and DU145 cells by MTT, colony formation and transwell assays, and affected cell cycle progression in PC-3 and DU145 cells by flow cytometry. Moreover, SMC1A knockdown significantly reduced tumor growth in vivo in a nude mouse model. Additionally, we also found that the expression of SMC1A gene was higher in prostate cancer tissues than in the adjacent normal tissues by immunohistochemical staining, and was positively correlated to tumor metastasis and recurrence by Oncomine database mining. Taken together, the present study indicates that SMC1A may play an important role in malignant transformation of PCa under conditions of androgen deprivation and act as a new target for PCa diagnosis and treatment.

Loss of asparagine synthetase suppresses the growth of human lung cancer cells by arresting cell cycle at G0/G1 phase

The aim of this research is to determine the role of human asparagine synthetase (ASNS) in human lung cancer. In the present study, immunohistochemical staining and the Oncomine database mining showed that the expression of ASNS gene was higher in lung cancer tissues than that in the normal tissues by. In addition, western blot assay showed that ASNS was elevated in lung cancer A549 and 95D cell lines as compared with that in H1299 and H460 cells. Therefore, A549 and 95D cells were chosen for subsequent MTT and colony formation assay. It was found that knockdown of ASNS inhibited the growth and colony formation abilities of A549 and 95D cells. Flow cytometry showed that ASNS silencing arrested cell cycle progression at G0/G1 phase in A549 cells, probably through regulating the expression of cell cycle molecules such as CDK2 and Cyclin E1 as shown by quantitative real-time PCR. Taken together, our study indicates that ASNS may be an important target for lung cancer diagnosis and treatment.

Computational Identification of Novel Stage-Specific Biomarkers in Colorectal Cancer Progression

It is well-known that the conversion of normal colon epithelium to adenoma and then to carcinoma stems from acquired molecular changes in the genome. The genetic basis of colorectal cancer has been elucidated to a certain extent, and much remains to be known about the identity of specific cancer genes that are associated with the advancement of colorectal cancer from one stage to the next. Here in this study we attempted to identify novel cancer genes that could underlie the stage-specific progression and metastasis of colorectal cancer. We conducted a stage-based meta-analysis of the voluminous tumor genome-sequencing data and mined using multiple approaches for novel genes driving the progression to stage-II, stage-III and stage-IV colorectal cancer. The consensus of these driver genes seeded the construction of stage-specific networks, which were then analyzed for the centrality of genes, clustering of subnetworks, and enrichment of gene-ontology processes. Our study identified three novel driver genes as hubs for stage-II progression: DYNC1H1, GRIN2A, GRM1. Four novel driver genes were identified as hubs for stage-III progression: IGF1R, CPS1, SPTA1, DSP. Three novel driver genes were identified as hubs for stage-IV progression: GSK3B, GGT1, EIF2B5. We also identified several non-driver genes that appeared to underscore the progression of colorectal cancer. Our study yielded potential diagnostic biomarkers for colorectal cancer as well as novel stage-specific drug targets for rational intervention. Our methodology is extendable to the analysis of other types of cancer to fill the gaps in our knowledge.

Molecular biomarkers in colorectal carcinoma

Colorectal cancer is a tumor with increasing incidence which represents one of the first leading causes of death worldwide. Gene alterations described for colorectal cancer include genome instability (microsatellite and chromosomal instability), CpG islands methylator phenotype, microRNA, histone modification, protein biomarkers, gene mutations (RAS, BRAF, PI3K, TP53, PTEN) and polymorphisms (APC, CTNNB1, DCC). In this article, biomarkers with prognostic value commonly found in colorectal cancer will be reviewed.