RNAi-mediated silencing of Anxa2 inhibits breast cancer cell proliferation by downregulating cyclin D1 in STAT3-dependent pathway. Breast Cancer Res Treat. 2015;153:263-275. [PMID: 26253946 DOI: 10.1007/s10549-015-3529-6]

Identification of Homoharringtonine as a potent inhibitor of glioblastoma cell proliferation and migration

We previously demonstrated that Annexin A2 (ANXA2) is a pivotal mediator of the pro-oncogenic features displayed by glioblastoma (GBM) tumors, the deadliest adult brain malignancies, being involved in cell stemness, proliferation and invasion, thus negatively impacting patient prognosis. Based on these results, we hypothesized that compounds able to revert ANXA2-dependent transcriptional features could be exploited as reliable treatments to inhibit GBM cell aggressiveness by hampering their proliferative and migratory potential. Transcriptional signatures obtained by the modulation of ANXA2 activity/levels were functionally mapped through the QUADrATiC bioinformatic tool for compound identification. Selected compounds were screened by cell proliferation and migration assays in primary GBM cells, and we identified Homoharringtonine (HHT) as a potent inhibitor of GBM cell motility and proliferation, without affecting their viability. A further molecular characterization of the effects displayed by HHT, confirmed its ability to inhibit a transcriptional program involved in cell migration and invasion. Moreover, we demonstrated that the multiple antitumoral effects displayed by HHT are correlated to the inhibition of a platelet derived growth factor receptor α (PDGFRα)-dependent intracellular signaling through the impairment of Signal transducer and activator of transcription 3 (STAT3) and Ras homolog family member A (RhoA) axes. Our results demonstrate that HHT may act as a potent inhibitor of cancer cell proliferation and invasion in GBM, by hampering multiple PDGFRα-dependent oncogenic signals transduced through the STAT3 and RhoA intracellular components, finally suggesting its potential transferability for achieving an effective impairment of peculiar GBM hallmarks.

Role of STAT3 in the initiation, progression, proliferation and metastasis of breast cancer and strategies to deliver JAK and STAT3 inhibitors

INTRODUCTION

Breast cancer (BC) accounts for the majority of cancers among the female population. Anomalous activation of various signaling pathways has become an issue of concern. The JAK-STAT signaling pathway is activated in numerous cancers, including BC. STAT3 is widely involved in BCs, as 40 % of BCs display phosphorylated STAT3. JAK-STAT signaling is crucial for proliferation, survival, metastasis and other cellular events associated with the tumor microenvironment. Hence, targeting this pathway has become an area of interest among researchers.

KEY FINDINGS

This review article focuses on the role of STAT3 in the initiation, proliferation, progression and metastasis of BC. The roles of various phytochemicals, synthetic molecules and biologicals against JAK-STAT and STAT3 in various cancers have been discussed, with special emphasis on BC.

SIGNIFICANCE

JAK and STAT3 are involved in various phases from initiation to metastasis, and targeting this pathway is a promising approach to inhibit the various stages of BC development and to prevent metastasis. A number of phytochemicals and synthetic and biological molecules have demonstrated potential inhibitory effects on JAK and STAT3, thereby paving the way for the development of better therapeutics against BC.

Annexin A2: The Diversity of Pathological Effects in Tumorigenesis and Immune Response

Annexin A2 (ANXA2) is widely used as a marker in a variety of tumors. By regulating multiple signal pathways, ANXA2 promotes the epithelial-mesenchymal transition, which can cause tumorigenesis and accelerate thymus degeneration. The elevated ANXA2 heterotetramer facilitates the production of plasmin, which participates in pathophysiologic processes such as tumor cell invasion and metastasis, bleeding diseases, angiogenesis, inducing the expression of inflammatory factors. In addition, the ANXA2 on the cell membrane mediates immune response via its interaction with surface proteins of pathogens, C1q, toll-like receptor 2, anti-dsDNA antibodies and immunoglobulins. Nuclear ANXA2 plays a role as part of a primer recognition protein complex that enhances DNA synthesis and cells proliferation by acting on the G1-S phase of the cell. ANXA2 reduction leads to the inhibition of invasion and metastasis in multiple tumor cells, bleeding complications in acute promyelocytic leukemia, retinal angiogenesis, autoimmunity response and tumor drug resistance. In this review, we provide an update on the pathological effects of ANXA2 in both tumorigenesis and the immune response. We highlight ANXA2 as a critical protein in numerous malignancies and the immune host response.

Identification of dysregulated competing endogenous RNA networks in glioblastoma: A way toward improved therapeutic opportunities

Glioblastoma is recognized as one of the leading causes of death worldwide. Although there have been considerable advancements in understanding the causative molecular mechanisms of this malignancy, effective therapeutic strategies are still in limited use. It has been revealed that non-coding RNAs (ncRNAs) play critical roles in glioblastoma development, while interactions between the regulatory molecules such as long ncRNAs (lncRNAs), microRNAs (miRNAs), transcribed pseudogenes, and circular RNAs (circRNAs) remain to be fully deciphered. Over the recent years, researchers have discovered a new category of RNA molecules called competing endogenous RNA (ceRNA). This kind of RNA can contribute to molecular interactions in the form of ceRNA networks (ceRNETs). Multiple lines of evidence have demonstrated that dysregulation of various ceRNA networks is involved in glioblastoma development. Therefore, gaining insights into these dysregulations might offer potential for the early diagnosis of glioblastoma patients and identification of efficient therapeutic targets. In this review, we provide an overview of recent discoveries on ceRNA networks and the involvement of dysregulated networks in posing limitations to temozolomide therapy. We also describe signaling pathways relevant to the progression of glioblastoma.

Overexpression of Annexin A2 promotes proliferation by forming a Glypican 1/c-Myc positive feedback loop: prognostic significance in human glioma

In order to set up a reliable prediction system for the tumor grade and prognosis in glioma patients, we clarify the complicated crosstalk of Annexin A2 (ANXA2) with Glypican 1 (GPC1) and demonstrate whether combined indexes of ANXA2 and GPC1 could improve the prognostic evaluation for glioma patients. We found that ANXA2-induced glioma cell proliferation in a c-Myc-dependent manner. ANXA2 increased the expression of GPC1 via c-Myc and the upregulated GPC1 further promoted the c-Myc level, forming a positive feedback loop, which eventually led to enhanced proliferation of glioma cells. Both mRNA and protein levels of ANXA2 were upregulated in glioma tissues and coincided with the overexpression of GPC1. Besides, we utilized tissue microarrays (TMAs) and immunohistochemistry to demonstrate that glioma patients with both high expression of ANXA2 and GPC1 tended to have higher rate of tumor recurrence and shorter overall survival (OS). In conclusion, the overexpression of ANXA2 promotes proliferation of glioma cells by forming a GPC1/c-Myc positive feedback loop, and ANXA2 together with its downstream target GPC1 could be a potential "combination biomarker" for predicting prognosis of glioma patients.

Identification and Analysis of the Blood lncRNA Signature for Liver Cirrhosis and Hepatocellular Carcinoma

As one of the most common malignant tumors, hepatocellular carcinoma (HCC) is the fifth major cause of cancer-associated mortality worldwide. In 90% of cases, HCC develops in the context of liver cirrhosis and chronic hepatitis B virus (HBV) infection is an important etiology for cirrhosis and HCC, accounting for 53% of all HCC cases. To understand the underlying mechanisms of the dynamic chain reactions from normal to HBV infection, from HBV infection to liver cirrhosis, from liver cirrhosis to HCC, we analyzed the blood lncRNA expression profiles from 38 healthy control samples, 45 chronic hepatitis B patients, 46 liver cirrhosis patients, and 46 HCC patients. Advanced machine-learning methods including Monte Carlo feature selection, incremental feature selection (IFS), and support vector machine (SVM) were applied to discover the signature associated with HCC progression and construct the prediction model. One hundred seventy-one key HCC progression-associated lncRNAs were identified and their overall accuracy was 0.823 as evaluated with leave-one-out cross validation (LOOCV). The accuracies of the lncRNA signature for healthy control, chronic hepatitis B, liver cirrhosis, and HCC were 0.895, 0.711, 0.870, and 0.826, respectively. The 171-lncRNA signature is not only useful for early detection and intervention of HCC, but also helpful for understanding the multistage tumorigenic processes of HCC.

ANXA2 Silencing Inhibits Proliferation, Invasion, and Migration in Gastric Cancer Cells

Annexin A2 (ANXA2) has been well known to associate with the progress of malignant tumor. However, the biological behavior of ANXA2 in gastric cancer (GC) remains unclear. We made a hypothesis in transcriptome level from TCGA datasets. Then, we used immunohistochemical staining to quantify the expression level of ANXA2 protein in GC tissues compared with adjacent tissues. Quantitative real-time PCR and western blot were used for analyzing ANXA2 expression in human GC (SGC-7901, MKN-45, BGC-823, and AGS) cell lines. We investigated the effect of a lentivirus-mediated knock-down of ANXA2 on the proliferation, invasion and migration of gastric cancer AGS cells. Cell proliferation was examined by MTT and colony formation tests. Cell apoptosis and cycle were measured by flow cytometry. Migration and invasion were detected by transwell assay. We found that high expression of ANXA2 can increase the mobility of cancer cells from TCGA datasets. ANXA2 was upregulated in GC tissues compared with adjacent tissues. AGS cell line displayed significantly higher expression of ANXA2 among the four GC cell lines. In addition, ANXA2 silencing led to a weakened ability of proliferation, invasion, and migration in GC cells; targeting of ANXA2 may be a potential therapeutic strategy for GC patients.

The miR155HG/miR-185/ANXA2 loop contributes to glioblastoma growth and progression

Background

Glioblastoma multiforme (GBM) is the most common and aggressive form of astrocytoma among adult brain tumors. Multiple studies have shown that long non-coding RNAs (lncRNAs) play important roles in acting as molecular sponge for competing with microRNAs (miRNAs) to regulate downstream molecules in tumor progression. We previously reported that miR155 host gene (miR155HG), an lncRNA, and its derivative miR-155 promote epithelial-to-mesenchymal transition in glioma. However, the other biological functions and mechanisms of miR155HG sponging miRNAs have been unknown. Considering ANXA2 has been generally accepted as oncogene overexpressed in a vast of cancers correlated with tumorigenesis, which might be the target molecule of miR155HG sponging miRNA via bioinformatics analysis. We designed this study to explore the interaction of miR155HG and ANXA2 to reveal the malignancy of them in GBM development.

Methods

The expression of miR155HG was analyzed in three independent databases and clinical GBM specimens. Bioinformatics analysis was performed to assess the potential tumor-related functions of miR155HG. The interaction of miR155HG and miR-185 and the inhibition of ANXA2 by miR-185 were analyzed by luciferase reporter experiments, and biological effects in GBM were explored by colony formation assays, EDU cell proliferation assays, flow cytometric analysis and intracranial GBM mouse model. Changes in protein expression were analyzed using western blot. We examined the regulatory mechanism of ANXA2 on miR155HG in GBM by gene expression profiling analysis, double immunofluorescence staining, chromatin immunoprecipitation and luciferase reporter assays.

Results

We found that miR155HG was upregulated in GBM tissues and cell lines. Bioinformatic analyses of three GBM databases showed that miR155HG expression levels were closely associated with genes involved in cell proliferation and apoptosis. Knocking down miR155HG suppressed GBM cell proliferation in vitro, induced a G1/S-phase cell cycle arrest, and increased apoptosis. We also found that miR155HG functions as a competing endogenous RNA for miR-185. Moreover, miR-185 directly targets and inhibits ANXA2, which exhibits oncogenic functions in GBM. We also found that ANXA2 promoted miR155HG expression via STAT3 phosphorylation.

Conclusion

Our results demonstrated that overexpressed miR155HG in GBM can sponge miR-185 to promote ANXA2 expression, and ANXA2 stimulates miR155HG level through phosphorylated STAT3 binding to the miR155HG promoter. We establish the miR155HG/miR185/ANXA2 loop as a mechanism that underlies the biological functions of miR155HG and ANXA2 in GBM and further suggest this loop may serve as a therapeutic target and/or prognostic biomarker for GBM.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1132-0) contains supplementary material, which is available to authorized users.

Long non-coding RNA LUCAT1 promotes tumourigenesis by inhibiting ANXA2 phosphorylation in hepatocellular carcinoma

Long non‐coding RNAs (lncRNAs) play essential roles in diverse biological processes; however, current understanding of the mechanism underlying the regulation of tumour proliferation and metastasis is limited. Lung cancer‐associated transcript 1 (LUCAT1) has been reported in a variety of human cancers, while its role in hepatocellular carcinoma (HCC) remains unclear. This study aimed to determine the biological role and underlying mechanism of LUCAT1 on progression and metastasis in HCC cells and clinical specimens. Our results demonstrated that LUCAT1 was up‐regulated in HCC tissues and cells. Loss‐ and gain‐of‐function studies revealed that LUCAT1 promotes the proliferation and metastasis of HCC cells in vitro and in vivo. Furthermore, RNA pulldown and Western blot assays indicated that LUCAT1 inhibited the phosphorylation of Annexin A2 (ANXA2) to reduce the degradation of ANXA2‐S100A10 heterotetramer (AIIt), which in turn accelerated the secretion of plasminogen into plasmin, thereby resulting in the activation of metalloprotease proteins. In conclusion, we propose that LUCAT1 serves as a novel diagnostic and therapeutic target for HCC.

Ganoderic acid A exerts antitumor activity against MDA-MB-231 human breast cancer cells by inhibiting the Janus kinase 2/signal transducer and activator of transcription 3 signaling pathway

Breast cancer is a common malignant tumor among females, with triple-negative breast cancer being an important type accounting for 15–20% of all breast cancer cases. Triple-negative breast cancer is one of the most aggressive types of cancer without standard adjuvant chemotherapy. Ganoderic acid A (GA-A) is one of the major bioactive Ganoderma triterpenoids isolated from Ganoderma, which are recognized for their preventative and therapeutic effects. In the present study, the antineoplastic effect of GA-A on human breast cancer was investigated and the pro-apoptotic function of Janus kinase (JAK)2 and signal transducer and activator of transcription (STAT)3 on the function of GA-A was revealed. GA-A treatment inhibited the invasion of MDA-MB-231 cells. In addition, GA-A exhibited significant antitumor activity by enhancing the apoptotic index and reactive oxygen species production. In the present study, GA-A was identified to directly inhibit JAK2 phosphorylation and STAT3 downstream activation. In addition, GA-A suppressed STAT3 target gene expression, including B cell lymphoma-extra-large and Myeloid cell leukemia 1, resulting in elevated levels of proteins associated with mitochondrial apoptosis in addition to inhibitors of cyclin-dependent kinase. GA-A, in combination with AG490, a JAK2/STAT3 inhibitor, further decreased MDA-MB-231 cell viability. In conclusion, GA-A treatment inhibited breast cancer cell viability via JAK2/STAT3 downregulation and may regulate associated targets to serve an anti-MDA-MB-231 role, including mitochondrial apoptosis and regulating the expression of cell-cycle-associated factors.

Annexin A1 regulates EGFR activity and alters EGFR-containing tumour-derived exosomes in head and neck cancers

BACKGROUND

Head and neck squamous cell carcinoma (HNSCC) is the 6th most common cancer with approximately half a million cases diagnosed each year worldwide. HNSCC has a poor survival rate which has not improved for over 30 years. The molecular pathogenesis of HNSCCs remains largely unresolved; there is high prevalence of p53 mutations and EGFR overexpression; however, the contribution of these molecular changes to disease development and/or progression remains unknown. We have recently identified microRNA miR-196a to be highly overexpressed in HNSCC with poor prognosis. Oncogenic miR-196a directly targets Annexin A1 (ANXA1). Although increased ANXA1 expression levels have been associated with breast cancer development, its role in HNSCC is debatable and its functional contribution to HNSCC development remains unclear.

METHODS

ANXA1 mRNA and protein expression levels were determined by RNA Seq analysis and immunohistochemistry, respectively. Gain- and loss-of-function studies were performed to analyse the effects of ANXA1 modulation on cell proliferation, mechanism of activation of EGFR signalling as well as on exosome production and exosomal phospho-EGFR.

RESULTS

ANXA1 was found to be downregulated in head and neck cancer tissues, both at mRNA and protein level. Its anti-proliferative effects were mediated through the intracellular form of the protein. Importantly, ANXA1 downregulation resulted in increased phosphorylation and activity of EGFR and its downstream PI3K-AKT signalling. Additionally, ANXA1 modulation affected exosome production and influenced the release of exosomal phospho-EGFR.

CONCLUSIONS

ANXA1 acts as a tumour suppressor in HNSCC. It is involved in the regulation of EGFR activity and exosomal phospho-EGFR release and could be an important prognostic biomarker.

E3 Ligase Trim21 Ubiquitylates and Stabilizes Keratin 17 to Induce STAT3 Activation in Psoriasis

Keratin 17 (K17), a marker of keratinocyte hyperproliferation, is a type I intermediate filament that is overexpressed in psoriatic epidermis and plays a critical pathogenic role by stimulating T cells. However, the posttranslational modification of K17, which is reversible and targetable, has not been elucidated. Herein, we reported that K17 could be modified through ubiquitination that controlled its stability and led to the phosphorylation and nuclear translocation of its interactor signal transducers and activators of transcription 3 (STAT3), which is a key regulator of cell proliferation in psoriasis. First, we stimulated human keratinocyte cell line HaCaT cells with psoriasis (pso)-mix, which is a cytokine pool (IL-17, IL-22, tumor necrosis factor-α, and IFN-γ) mimicking the in vitro "psoriasis-like" status and found that the ubiquitination of K17 was essential to stabilize its protein expression in pso-mix-treated HaCaT cells. Subsequently, tripartite motif-containing protein 21 was identified as the E3 ligase of K17, which ubiquitylated K17 via K63 linkage to maintain K17 stabilization. More importantly, we uncovered that K17 was a direct interactor of STAT3, and K17 ubiquitination could promote STAT3 activation in pso-mix-treated HaCaT cells. Our study demonstrated that targeting K17 ubiquitination may be a potential therapeutic approach by attenuating STAT3 signaling in psoriasis.

MicroRNA-411 Inhibits Cervical Cancer Progression by Directly Targeting STAT3

Cervical cancer is the third most common gynecological cancer and the fourth leading cause of cancer-related deaths in women around the world. Substantial evidence has demonstrated that microRNA (miRNA) expression is disordered in many malignant tumors. The dysregulation of miRNAs has been suggested to be involved in the tumorigenesis and tumor development of cervical cancer. Therefore, identification of miRNAs and their biological roles and targets involved in tumor pathology would provide valuable insight into the diagnosis and treatment of patients with cervical cancer. MicroRNA-411 (miR-411) has been reported to play an important role in several types of human cancer. However, the expression level, role, and underlying molecular mechanisms of miR-411 in cervical cancer remain unclear. Therefore, the objectives of this study were to investigate the expression pattern and clinical significance of miR-411 in cervical cancer and to evaluate its role and underlying mechanisms in this disease. In this study, we confirmed that the expression of miR-411 was significantly downregulated in both cervical cancer tissues and cell lines. Low expression of miR-411 was associated with tumor size, FIGO stage, lymph node metastasis, and distant metastasis. Additionally, miR-411 overexpression inhibited cell proliferation and invasion in cervical cancer. Furthermore, signal transducer and activator of transcription 3 (STAT3) was identified as a direct target of miR-411 in this disease. In clinical samples, miR-411 expression levels were inversely correlated with STAT3, which was significantly upregulated in cervical cancer. Restored STAT3 expression abolished the tumor-suppressing effects of miR-411 overexpression on the proliferation and invasion of cervical cancer cells. In conclusion, our data demonstrated that miR-411 inhibited cervical cancer progression by directly targeting STAT3 and may represent a novel potential therapeutic target and prognostic marker for patients with this disease.

Molecular cloning and expression analysis of annexin A2 gene in sika deer antler tip

OBJECTIVE

Molecular cloning and bioinformatics analysis of annexin A2 (ANXA2) gene in sika deer antler tip were conducted. The role of ANXA2 gene in the growth and development of the antler were analyzed initially.

METHODS

The reverse transcriptase polymerase chain reaction (RT-PCR) was used to clone the cDNA sequence of the ANXA2 gene from antler tip of sika deer (Cervus Nippon hortulorum) and the bioinformatics methods were applied to analyze the amino acid sequence of Anxa2 protein. The mRNA expression levels of the ANXA2 gene in different growth stages were examined by real time reverse transcriptase polymerase chain reaction (real time RT-PCR).

RESULTS

The nucleotide sequence analysis revealed an open reading frame of 1,020 bp encoding 339 amino acids long protein of calculated molecular weight 38.6 kDa and isoelectric point 6.09. Homologous sequence alignment and phylogenetic analysis indicated that the Anxa2 mature protein of sika deer had the closest genetic distance with Cervus elaphus and Bos mutus. Real time RT-PCR results showed that the gene had differential expression levels in different growth stages, and the expression level of the ANXA2 gene was the highest at metaphase (rapid growing period).

CONCLUSION

ANXA2 gene may promote the cell proliferation, and the finding suggested Anxa2 as an important candidate for regulating the growth and development of deer antler.

Tyr23 phosphorylation of Anxa2 enhances STAT3 activation and promotes proliferation and invasion of breast cancer cells

PURPOSE

Overexpression of Annexin A2 (Anxa2) is positively correlated with breast cancer progression, drug resistance, and poor prognosis of patients with breast cancer. Tyr23 Phosphorylation by Src-family tyrosine kinase is an important post-translational modification of Anxa2. This modification regulates the subcellular localization and functions of Anxa2 and has significant effects on cell proliferation, migration, and invasion. This study aims at revealing the association of Anxa2-Tyr23 phosphorylation in Anxa2-mediated acceleration of breast cancer progression and their elaborate molecular mechanisms.

METHODS

Cell biological function experiments were performed to determine the effects of Anxa2-Tyr23 Phosphorylation on breast cancer cell proliferation and invasion in vitro and metastasis in vivo. The interaction of Tyr23 phosphorylated Anxa2 and STAT3 was verified by co-immunoprecipitation assay. Related mRNA and protein expression levels of cyclin D1 and MMP2/9 and phosphorylation level of STAT3 were detected.

RESULTS

Anxa2-Tyr23 phosphorylation is necessary for proliferation, invasion, and metastasis of breast cancer cells in vitro and in vivo. Tyr23 phosphorylated Anxa2 binds and enhances the sensitivity of STAT3 activation in response to IL-6, thereby increasing the protein and mRNA expression levels of cyclin D1 and MMP2/9 which are STAT3 key target genes and serve pivotal regulatory functions in cell proliferation and invasion, respectively.

CONCLUSION

Our findings further confirmed the regulatory role of Anxa2 and revealed the direct relationship between Anxa2-Tyr23 phosphorylation and activation of STAT3. Moreover, this study provides novel insights into the function of Anxa2-Tyr23 phosphorylation in signal transduction for further understanding of the mechanism through which Anxa2 promotes the progression of breast cancer.

Annexin A2 inhibition suppresses ovarian cancer progression via regulating β-catenin/EMT

Annexin A2 is a member of the Annexin family that acts as a Ca2+-dependent phospholipid and membrane binding protein, which is associated with the survival and spread of multiple neoplasms. However, the function of Annexin A2 in ovarian cancer progression remains unclear. In this study, we aimed to investigate the role and underlying molecular mechanism of Annexin A2 in cell proliferation and invasion in ovarian cancer. We found that the mRNA expression of Annexin A2 was upregulated in ovarian cancer tissues and cell lines. In the loss-of-function of Annexin A2, β-catenin was indicated to be significantly suppressed and EMT constrained. Moreover, cell proliferation and invasion were both markedly inhibited by the downregulation of Annexin A2. Additionally, the overexpression of β-catenin obviously reversed the effect of Annexin A2 on EMT, and cell proliferation and invasion, indicating that Annexin A2 suppression regulated EMT through controlling β-catenin. Taken together, this study showed that Annexin A2 inhibition suppresses proliferation and invasion in ovarian cancer via β-catenin/EMT, proposing the potential role of Annexin A2 in the prevention and treatment of ovarian cancer.

miR-1181 inhibits invasion and proliferation via STAT3 in pancreatic cancer

AIM

To examine the role of microRNA 1181 (miR-1181) in invasion and proliferation in pancreatic cancer.

METHODS

We analyzed the expression of miR-1181 in several pancreatic cancer cell lines and generated stable MIA-PaCa-2 and PANC-1 cell lines with up-regulated miR-1181 expression using an adenovirus delivery system. We then investigated miR-1181's effect on invasion and proliferation of pancreatic cancer cells by transwell assay, wound healing assay, cell counting kit-8 assay and colony-forming assay, and explored any underlying mechanisms by western bolt. Beyond that, we observed the change of the PANC-1 cell's cytoskeleton by immunofluorescence staining.

RESULTS

Our data showed that miR-1181 was relatively down-regulated in pancreatic cancer cell lines compared with normal pancreatic ductal epithelial cells. And miR-1181 inhibited the migration, invasion and proliferation activities of MIA-PaCa-2 and PANC-1 cells. Notably, after over-expressing of miR-1181 in PANC-1 cells, F-actin depolymerized. Immunofluorescence staining shows decreased F-actin and β-tubulin expression in PANC-1 cells over-expressing miR-1181 compared with the control cells. Furthermore, we found that over-expressing miR-1181 inhibited the expression of signal transducer and activator of transcription 3 (STAT3) while knocking-down miR-1181 up-regulated the expression of STAT3. Knocking-down miR-1181 promoted the invasion and proliferation of pancreatic cancer cells. And inhibition of STAT3 blocked the promotion effects of knocking-down miR-1181 on proliferation and invasion in pancreatic cancer.

CONCLUSION

Together our findings suggest that miR-1181 may be involved in pancreatic cancer cell invasion and proliferation by targeting STAT3 and indicate that miR-1181 may be a potential therapeutic agent for pancreatic cancer.

The upregulation of annexin A2 after spinal cord injury in rats may have implication for astrocyte proliferation

Annexin A2 (ANXA2), is a member of the annexin family of proteins that exhibit Ca²⁺-dependent binding to phospholipids. One attractive biological function of ANXA2 is participating in DNA synthesis and cell proliferation. Previous studies have shown that ANXA2 play a role in the development of the central nervous system. However, the biological function of ANXA2 after spinal cord injury (SCI) is still with limited acquaintance. In the present study, we performed a SCI model in adult rats and investigated the dynamic changes of ANXA2 expression in the spinal cord. Western blot analysis indicated a striking expression upregulation of ANXA2 after SCI. Immunohistochemistry further confirmed that ANXA2 immunoactivity was expressed at low levels in normal condition and increased at 5day after SCI. Double immunofluorescence staining prompted that ANXA2 immunoreactivity was found in astrocytes and neurons. Interestingly, ANXA2 expression was increased predominantly in astrocytes. We also examined the expression profiles of proliferating cell nuclear antigen (PCNA), Cyclin D1 and active caspase-3 in the injured spinal cords by western blot. Co-expression of ANXA2/PCNA, ANXA2/Cyclin D1 was detected in glial fibrillary acidic protein. Importantly, double immunofluorescence staining revealed that cell proliferation evaluated by PCNA appeared in many ANXA2-expressing cells and rare caspase-3 was observed in ANXA2-expressing cells after SCI. In addition, ANXA2 knockdown in astrocytes resulted in the increase of PCNA expression after LPS stimulation, showing that ANXA2 inhibited astrocyte proliferation after inflammation. Our data suggested that ANXA2 might play important roles in CNS pathophysiology after SCI.

Berberine promotes proliferation of sodium nitroprusside-stimulated rat chondrocytes and osteoarthritic rat cartilage via Wnt/β-catenin pathway

Berberine chloride (BBR) is an isoquinoline derivative alkaloid isolated from medicinal herbs, including Coptis chinensis and Berberis aristate. This compound plays significant roles in the treatment of osteoarthritis (OA). The purpose of this study was to investigate the effects of BBR on the proliferation of sodium nitroprusside (SNP)-stimulated chondrocytes in vitro, the articular cartilage in a rat OA model, as well as to discuss the molecular mechanisms underlying these effects. In vitro, we demonstrated that BBR led to cell proliferation, increased the cell population in S-phase and decreased that in G0/G1-phase; moreover, the F-actin remodeling in SNP-stimulated chondrocytes were prevented. In addition, BBR markedly up-regulated β-catenin, c-Myc, and cyclin D1 expression of genes and proteins, and down-regulated glycogen synthase kinase-3β (GSK-3β) and matrix metalloproteinase-7 (MMP-7) expression. Notably, inhibition of the Wnt/β-catenin pathway by XAV939 partially blocked these effects. The in vivo results suggested that BBR promoted β-catenin protein level and enhanced proliferating cell nuclear antigen (PCNA) expression in osteoarthritic rat cartilage. In conclusion, these findings indicate that BBR promotes SNP-stimulated chondrocyte proliferation by promoting G1/S phase transition and synthesis of PCNA in cartilage through activation of Wnt/β-catenin signaling pathway.

Elevated STAT3 Signaling-Mediated Upregulation of MMP-2/9 Confers Enhanced Invasion Ability in Multidrug-Resistant Breast Cancer Cells

The development of multidrug resistance greatly impedes effective cancer therapy. Recent advances in cancer research have demonstrated that acquisition of multidrug resistance by cancer cells is usually accompanied by enhanced cell invasiveness. Several lines of evidence indicated that cross activation of other signaling pathways during development of drug resistance may increase invasive potential of multidrug-resistant (MDR) cancer cells. However, the accurate mechanism of this process is largely undefined. In this study, to better understand the associated molecular pathways responsible for cancer progression induced by drug resistance, a MDR human breast cancer cell line SK-BR-3/EPR with P-glycoprotein overexpression was established using stepwise long-term exposure to increasing concentration of epirubicin. The SK-BR-3/EPR cell line exhibited decreased cell proliferative activity, but enhanced cell invasive capacity. We showed that the expression of metastasis-related matrix metalloproteinase (MMP)-2/9 was elevated in SK-BR-3/EPR cells. Moreover, SK-BR-3/EPR cells showed elevated activation of STAT3. Activation of STAT3 signaling is responsible for enhanced invasiveness of SK-BR-3/EPR cells through upregulation of MMP-2/9. STAT3 is a well-known oncogene and is frequently implicated in tumorigenesis and chemotherapeutic resistance. Our findings augment insight into the mechanism underlying the functional association between MDR and cancer invasiveness.