CTGF increases matrix metalloproteinases expression and subsequently promotes tumor metastasis in human osteosarcoma through down-regulating miR-519d

LATS1 suppresses proliferation and invasion of cervical cancer

Loss of large tumor suppressor kinase 1 (LATS1)Y has been implicated in numerous types of human cancer. However, its involvement in human cervical cancer remains to be elucidated. The present study aimed to investigate the clinical significance and biological characteristics of LATS1 in human cervical cancer. The present study investigated the protein expression levels of LATS1 in tissues from 80 cases of cervical cancer using immunohistochemistry and demonstrated that LATS1 was downregulated in 45% (36/80) of cervical cancers. Transfection of LATS1 was performed in the SiHa cell line and LATS1 siRNA knockdown was performed in the Caski cell line. MTT assay and Matrigel invasion assay indicated that LATS1 overexpression inhibited cell proliferation and invasion. LATS1 overexpression upregulated p27 expression, and downregulated the expression of cyclin E and matrix metalloproteinase 9. In addition, LATS1 overexpression stimulated yes-associated protein 1 (YAP) phosphorylation. Depletion of LATS1 in Caski cells resulted in the opposite effects. The current study demonstrated that LATS1 was downregulated in cervical cancer and may suppress cell growth and invasion through regulating the expression of cyclin E, p27, MMP9 and YAP.

MicroRNA-379 suppresses osteosarcoma progression by targeting PDK1

Osteosarcoma is the most common primary bone tumour. Increasing evidence has demonstrated the pathogenic role of microRNA (miRNAs) dysregulation in tumour development. miR-379 was previously reported to function as an oncogenic or tumour-suppressing miRNA in a tissue-dependent manner. However, its function in osteosarcoma remains unknown. In this study, we found that the expression of miR-379 was downregulated in osteosarcoma tissues and cell lines. Further functional characterization revealed that miR-379 suppressed osteosarcoma cell proliferation and invasion in vitro and retarded the growth of osteosarcoma xenografts in vivo. Mechanistically, PDK1 was identified as the direct target of miR-379 in osteosarcoma, in which PDK1 expression was up-regulated and showed inverse correlation with miR-379. Enforced expression of PDK1 promoted osteosarcoma cell proliferation and rescued the anti-proliferative effect of miR-379. These data suggest that miR-379 could function as a tumour-suppressing miRNA via targeting PDK1 in osteosarcoma.

CTGF promotes osteosarcoma angiogenesis by regulating miR-543/angiopoietin 2 signaling

Osteosarcoma is the most common primary solid tumor of bone. It has a high metastatic potential and occurs predominantly in adolescents and young adults. Angiopoietin 2 (Angpt2) is a key regulator in tumor angiogenesis, facilitating tumor growth and metastasis. Connective tissue growth factor (CTGF, also known as CCN2), is a cysteine-rich protein that has been reported to promote metastasis of osteosarcoma. However, the effect of CTGF on Angpt2 regulation and angiogenesis in human osteosarcoma remains largely unknown. We found that overexpression of CTGF in osteosarcoma cells increased Angpt2 production and induced angiogenesis, in vitro and in vivo. Our findings demonstrate that CTGF-enhanced Angpt2 expression and angiogenesis is mediated by the phospholipase C (PLC)/protein kinase C (PKCδ) signaling pathway. Moreover, endogenous microRNA-543 (miR-543) expression was negatively regulated by CTGF via the PLC/PKCδ pathway. We also provide evidence showing clinical significance between CTGF, Angpt2, and miR-543 as well as tumor staging in human osteosarcoma tissue. CTGF may serve as a therapeutic target in the process of osteosarcoma metastasis and angiogenesis.

Zoledronate blocks geranylgeranylation not farnesylation to suppress human osteosarcoma U2OS cells metastasis by EMT via Rho A activation and FAK-inhibited JNK and p38 pathways

Zoledronate is a standard treatment for preventing skeletal complications of osteoporosis and some types of cancer associated with bone metastases, but we little know whether the effect of zoledronate on metastasis of osteosarcoma. Here, we investigated the inhibitory effects of zoledronate on cell viability, motility, migration and invasion of 4 osteosarcoma cell lines (Saos2, MG-63, HOS and U2OS) by affecting cell morphology, epithelial-mesenchymal transition (EMT) and cytoskeletal organization as well as induction of E-cadherin and reduction of N-cadherin with activation of transcription factors Slug and Twist, especially in U2OS cells. Zoledronate decreased JNK and p38 phosphorylation and upper streams of focal adhesion kinase (FAK) and Src to suppress the motility, invasiveness and migration of U2OS cells. In addition to zoledronate-inhibited Rho A and Cdc42 membrane translocation and GTPγS activities, the anti-metastatic effects in U2OS cells including inhibition of adhesion were reversed by geranylgeraniol, but not farnesol. In conclusion, Zoledronate blocks geranylgeranylation not farnesylation to suppress human osteosarcoma U2OS cell-matrix and cell-cell interactions, migration potential, the invasive activity, and the adhesive ability by EMT via Rho A activation and FAK-inhibited JNK and p38 pathways.

CTGF enhances resistance to 5-FU-mediating cell apoptosis through FAK/MEK/ERK signal pathway in colorectal cancer

Colorectal cancer (CRC) is one of the most commonly diagnosed cancers among both males and females; the chemotherapy drug 5-fluorouracil (5-FU) is one of a doctors’ first lines of defense against CRC. However, therapeutic failures are common because of the emergence of drug resistance. Connective tissue growth factor (CTGF) is a secreted protein that binds to integrins, and regulates the invasiveness and metastasis of certain carcinoma cells. Here, we found that CTGF was upregulated in drug-resistant phenotype of human CRC cells. Overexpression of CTGF enhanced the resistance to 5-FU-induced cell apoptosis. Moreover, downregulating the expression of CTGF promoted the curative effect of chemotherapy and blocked the cell cycle in the G1 phase. We also found that CTGF facilitated resistance to 5-FU-induced apoptosis by increasing the expression of B-cell lymphoma-extra large (Bcl-xL) and survivin. Then we pharmacologically blocked MEK/ERK signal pathway and assessed 5-FU response by MTT assays. Our current results indicate that the expression of phosphorylated forms of MEK/ERK increased in high CTGF expression cells and MEK inhibited increases in 5-FU-mediated apoptosis of resistant CRC cells. Therefore, our data suggest that MEK/ERK signaling contributes to 5-FU resistance through upstream of CTGF, and supports CRC cell growth. Comprehending the molecular mechanism underlying 5-FU resistance may ultimately aid the fight against CRC.

The pivotal role of CCN2 in mammalian palatogenesis

Mammalian palatogenesis is a complex process involving a temporally and spatially regulated myriad of factors. Together these factors control the 3 vital processes of proliferation, elevation and fusion of the developing palate. In this study, we show for the first time the unequivocally vital role of CCN2 in development of the mammalian palate. We utilized CCN2 knockout (KO) mice and cranial neural crest derived mesenchymal cells from these CCN2 KO mice to investigate the 3 processes crucial to normal palatogenesis. Similar to previously published reports, the absence of CCN2 inhibits proliferation of cells in the palate specifically at the G1/S transition. Absence of CCN2 also inhibited palatal shelf elevation from the vertical to horizontal position. CCN2 KO mesenchymal cells demonstrated deficiencies in adhesion and spreading owing to an inability to activate Rac1 and RhoA. On the contrary, CCN2 KO mesenchymal cells exhibited increased rates of migration compared to WT cells. The addition of exogenous CCN2 to KO mesenchymal cells restored their ability to spread normally on fibronectin. Finally, utilizing an organ culture model we show that the palatal shelves of the CCN2 KO mice demonstrate an inability to fuse when apposed. Together, these data signify that CCN2 plays an indispensible role in normal development of the mammalian palate and warrants additional studies to determine the precise mechanism(s) responsible for these effects.

The function of miR-519d in cell migration, invasion, and proliferation suggests a role in early placentation

The processes of proliferation, migration, and invasion of extravillous trophoblasts are critical for placental implantation and early development, and directly influence pregnancy outcome. Dysregulation of these processes has been associated with placental dysfunction, implicated in clinical conditions such as preeclampsia and placental accreta. Among diverse microRNA (miRNA) species that are expressed in placental trophoblasts, members of the chromosome 19 miRNA cluster (C19MC) stand out in their nearly exclusive expression in the placenta. Recent research on the function of C19MC miRNAs in normal cell physiology and during tumorigenesis identified one C19MC member, miR-519d, as a regulator of cell migration, invasion, and interaction with the extracellular matrix. In this review, we focus on the function of miR-519d in placental trophoblasts, where miR-519d regulates cell migration and invasion, and its aberrant expression is associated with preeclampsia. In cancer, the function of miR-519d as an oncomiR or a tumor-suppressor is dependent upon the tumor type. Further research on the biological function and regulation of miR-519d may illuminate previously unknown mechanisms that control cell migration and invasion.

Glucosamine sulfate suppresses the expression of matrix metalloproteinase-3 in osteosarcoma cells in vitro

Background

Glucosamine, a common dietary supplement, has a possible anti-sarcoma effect. However, an understanding of the underlying mechanism of such an effect is limited. For this study we hypothesized that glucosamine suppresses the basal level of matrix metalloproteinase expression in human osteosarcoma cell lines.

Methods

We examined the osteosarcoma cell lines, MG-63 and SaOS-2. Cells were exposed to 0, 10, 50 and 100 μg/ml glucosamine sulfate for 48 h and treatment toxicity was determined through measurement of cell viability and proliferation. Relative gene expression of matrix metalloproteinase (MMP)-2, -3 and -9 was quantified by real-time polymerase chain reaction. Protein levels of MMP-2 and -9 were assessed by ELISA.

Results

Administration of 10, 50 or 100 μg/ml glucosamine sulfate had no effect on the cell viability of MG-63 and SaOS-2 cells. A significant reduction of MMP expression in both cell lines was observed only for MMP-3, while a decrease in MMP-9 was seen in SaOS-2 cells. The expression of MMP-2 was not significantly affected in either cell line. Protein level of MMP-3 was reduced in both cell lines upon stimulation with 10 μg/ml glucosamine sulfate whereas for MMP-9 a decrease could only be observed in SaOS-2 cells.

Conclusion

In this study, we found a pronounced suppressive effect of glucosamine sulfate particularly on MMP-3 and also MMP-9 mRNA and protein levels in osteosarcoma cell lines in vitro. The data warrants further investigations into the potential anti-tumor efficacy of glucosamine sulfate in osteosarcoma.

Electronic supplementary material

The online version of this article (doi:10.1186/s12906-016-1315-6) contains supplementary material, which is available to authorized users.

p62/IMP2 stimulates cell migration and reduces cell adhesion in breast cancer

p62/IMP2 is an oncofetal protein that is overexpressed in several types of cancer, and is a member of the family of insulin-like growth factor 2 mRNA binding proteins. We previously reported that high levels of p62/IMP2 autoantibody are present in sera from cancer patients, compared to healthy individuals. Here, we report the overexpression of p62/IMP2 in tumor tissues of 72 out of 104 cases of human breast cancer, and high levels of p62/IMP2 autoantibody in patients’ sera (in 63 out of 216 cases). To explore the role of p62/IMP2 in breast cancer progression, we generated p62/IMP2 transfected variants of two human breast cancer cell lines: MDA-MB-231 and LM2-4. Using in vitro assays we found that overexpression of p62/IMP2 can increase cell migration, and reduce cell adhesion to extracellular matrix (ECM) proteins. A Human Extracellular Matrix and Adhesion Molecules qPCR array was performed with our generated variants, and it identified a group of mRNAs whose expression was altered with p62/IMP2 overexpression, including connective tissue growth factor (CTGF) mRNA – which we show to be a p62/IMP2 binding partner. Overall, our results provide new insights into the molecular mechanism by which p62/IMP2 can contribute to breast cancer progression.

Expression analysis of three miRNAs, miR-26a, miR-29b and miR-519d, in relation to MMP-2 expression level in non-small cell lung cancer patients: a pilot study

Lung cancer is the most common cause of death in men and second only to breast cancer in women. MicroRNAs (miRNAs) are involved in tumorigenesis and function as oncogenes or tumor suppressor genes. Among other genes, miRNAs regulate matrix metalloproteinases (MMPs), the proteolytic enzymes playing a significant role in the degradation of extracellular matrix, enhancing tumor invasion and metastasis. The aim of the study was to evaluate the expression levels of selected miRNAs: miR-26a, miR-29b and miR-519d, and their target gene, matrix metalloproteinase-2 (MMP-2) in patients with non-small cell lung cancer (NSCLC). The results were correlated with tumor staging, NSCLC histopathological subtypes and patients' demographical features to assess the possible diagnostic/prognostic value of the studied miRNAs and MMP-2. Total RNA was isolated from 38 NSCLC tissue samples, and the expression analysis was performed using TaqMan(®) probes in qPCR assay. The results indicated underexpression of selected miRNAs and overexpression of MMP-2. The decrease in miRNA-29b expression was statistically significant and differentiated NSCLC histopathological subtypes. Additionally, statistically significant negative correlation was found between MMP-2 expression and its regulatory miR-26a. There are very few studies reporting miRNA-MMPs analysis on mRNA level in lung cancer, and no similar reports are available from Polish population. The results of our pilot study indicated the diagnostic potential of miR-29b and MMP-2, an inverse association between miR-26a and MMP-2, and proved the role of MMP-2 and the studied miRNAs in lung carcinogenesis. Further studies are needed to verify their potential usefulness for the treatment of lung cancer.

Adiponectin promotes VEGF-C-dependent lymphangiogenesis by inhibiting miR-27b through a CaMKII/AMPK/p38 signaling pathway in human chondrosarcoma cells

Chondrosarcoma is the second most frequently occurring type of bone malignancy characterized by distant metastatic propensity. Vascular endothelial growth factor-C (VEGF-C) is the major lymphangiogenic factor, and makes crucial contributions to tumour lymphangiogenesis and lymphatic metastasis. Adiponectin is a protein hormone secreted predominantly by differentiated adipocytes. In recent years, adiponectin has also been indicated as facilitating tumorigenesis, angiogenesis and metastasis. However, the effect of adiponectin on VEGF-C regulation and lymphangiogenesis in chondrosarcoma has remained largely a mystery. In the present study, we have shown a clinical correlation between adiponectin and VEGF-C, as well as tumour stage, in human chondrosarcoma tissues. We further demonstrated that adiponectin promoted VEGF-C expression and secretion in human chondrosarcoma cells. The conditioned medium from adiponectin-treated cells significantly induced tube formation and migration of human lymphatic endothelial cells. In addition, adiponectin knock down inhibited lymphangiogenesis in vitro and in vivo We also found that adiponectin-induced VEGF-C is mediated by the calmodulin-dependent protein kinase II (CaMKII), AMP-activated protein kinase (AMPK) and p38 signaling pathway. Furthermore, the expression of miR-27b was negatively regulated by adiponectin via the CaMKII, AMPK and p38 cascade. The present study is the first to describe the mechanism of adiponectin-promoted lymphangiogenesis by up-regulating VEGF-C expression in chondrosarcomas. Thus, adiponectin could serve as a therapeutic target in chondrosarcoma metastasis and lymphangiogenesis.

MicroRNA-200a suppresses metastatic potential of side population cells in human hepatocellular carcinoma by decreasing ZEB2

Although microRNA-200a (miR-200a) is frequently downregulated in cancer, its role in side population (SP) has not been investigated. In this study, 101 pairs of primary hepatocellular carcinoma (HCC) tissues and matched normal control tissues were analyzed for miR-200a expression and its clinicopathological value was determined. We found that miR-200a was downregulated in HCC/SP and this was associated metastasis. MiR-200a suppressed metastasis of SP cells. Overexpression of miR-200a in SP cells decreased metastasis-related markers and expression of ZEB2. The associations between miR-200a, SP cells and ZEB2 were validated in HCC. These findings reveal that miR-200a suppresses metastasis of SP cells by downregulating ZEB2.

Genetic factors conferring metastasis in osteosarcoma

Osteosarcoma (OS) is a deadly bone malignancy affecting mostly children and adolescents. OS has outstandingly complex genetic alterations likely due to p53-independent genomic instability. Based on analysis of recent published research we claim existence of various genetic mechanisms of osteosarcomagenesis conferring great variability to different OS properties including metastatic potential. We also propose a model explaining how diverse genetic mechanisms occur and providing a framework for future research. P53-independent preexisting genomic instability, which precedes and frequently causes TP53 genetic alterations, is central in our model. In addition, our analyses reveal a possible cooperation between aberrantly activated HIF-1α and AP-1 genetic pathways in OS metastasis. We also review the involvement of noncoding RNA genes in OS metastasis.

MiR-519d facilitates the progression and metastasis of cervical cancer through direct targeting Smad7

Background

MicroRNAs (miRNAs) play pivotal roles in the development of various cancer types, including cervical cancer.

Methods and results

In this study, we showed that miR-519d, a miRNA within the chromosome 19 miRNA cluster, was significantly upregulated in cervical cancer tissues, compared with non-tumorous cervical samples. Suppression of miR-519d markedly attenuated the migration and invasion of HeLa and SiHa cervical cancer cells. Additionally, miR-519d inhibited the apoptosis of cervical cancer cells, and the proliferation of cervical cancer cells was also affected following transfection of miR-519d inhibitor. Moreover, we identified Smad7 to be a novel target of miR-519d in cervical cancer cells. MiR-519d matched the 3′-UTR of Smad7 mRNA. Transfection with miR-519d mimics led to apparent downregulation of Smad7 both at the mRNA and protein levels. Luciferase reporter analysis revealed that miR-519d reduced the luciferase activity of Smad7 mRNA 3′-UTR through matching site-dependent manner. And more notably, suppression of Smad7 remarkably restored the migration and invasion of miR-519d-depleted cervical cancer cells.

Conclusion

Taken together, these findings implicated that miR-519d promoted the progression and metastasis of cervical cancer through targeting Smad7.

Genetic variants of lncRNA HOTAIR contribute to the risk of osteosarcoma

Osteosarcoma (OS) is the most common primary malignant bone tumor in adolescents and young adults. However, the essential mechanisms underlying osteosarcomagenesis remain obscure. The HOTAIR, a well-known long noncoding RNA (lncRNA), is involved in pathogenesis and progress of multiple tumors. To reveal the potential role of lncRNA HOTAIR in OS carcinogenesis, we conducted a two-stage, case-control study among Chinese population with 900 OS cases and 900 controls to evaluated associations of its genetic variants with OS risk. We found that C allele of rs7958904 was associated with a significantly decreased OS risk when compared with G allele (OR: 0.77; 95% CI: 0.67-0.90; P = 6.77×10-4). Functional analyses on HOTAIR Expression showed that the expression level of HOTAIR in OS tissues was significantly higher than that in corresponding normal tissues, and subjects with the rs7958904 CC genotype had significantly lower HOTAIR RNA levels than those of other genotypes. This should be the first study to examine the association between HOTAIR variants and OS risk.

Long non-coding RNAs: emerging players in osteosarcoma

Osteosarcoma is the most common kind of primary bone tumors with high morbidity in infants and adolescents. While the molecular mechanism of osteosarcoma has gained considerable attention, the mechanisms underlying its initiation and progression remain unclear. Recent studies have discovered that long non-coding RNAs (lncRNAs) play an important role in multiply biological processes including cell development, differentiation, proliferation, invasion, and migration. Deregulated expression of lncRNAs has been found in cancers including osteosarcoma. This review summarized the deregulation and functional role of lncRNAs in osteosarcoma and their potential application for diagnosis and treatment of osteosarcoma.

PAQR3: a novel tumor suppressor gene

PAQR3, also known as RKTG (Raf kinase trapping to Golgi), is a member of the progestin and adipoQ receptor (PAQR) family. The role of PAQR3 as a tumor suppressor has recently been established in different types of human cancer in which PAQR3 exerts its biological function through negative regulation of the oncogenic Raf/MEK/ERK signaling. Multiple studies have found that PAQR3 downregulation frequently occurs in human cancers and is very often associated with tumor progression and shortened patients' survival. Moreover, restoring the expression of PAQR3 could induce apoptosis and inhibit proliferation and invasiveness of cancer cells. Downregulation of PAQR3 by oncogenic microRNAs has also been reported. In this review, we summarized current knowledge concerning the role of PAQR3 in tumor development. To our knowledge, this is the first review on the role of this novel tumor suppressor.

Resistin promotes tumor metastasis by down-regulation of miR-519d through the AMPK/p38 signaling pathway in human chondrosarcoma cells

Resistin is a recently discovered adipocyte-secreting adipokine, which may play a critical role in modulating cancer pathogenesis. Chondrosarcoma is a highly malignant tumor known to frequently metastasize; however, the role of resistin in the metastasis of human chondrosarcoma is largely unknown. Here, we found that the expression of resistin was higher in chondrosarcoma biopsy tissues than in normal cartilage. Moreover, treatment with resistin increased matrix metalloproteinase (MMP)-2 expression and promoted cell migration in human chondrosarcoma cells. Co-transfection with microRNA (miR)-519d mimic resulted in reversed resistin-mediated cell migration and MMP-2 expression. Additionally, AMP-activated protein kinase (AMPK) and p38 inhibitors or siRNAs reduced the resistin-increased cell migration and miR-519d suppression, and inhibition of resistin expression resulted in suppression of MMP-2 expression and lung metastasis in vivo. Taken together, our results indicate that resistin promotes chondrosarcoma metastasis and MMP-2 expression through activation of the AMPK/p38 signaling pathway and down-regulation of miR-519d expression. Therefore, resistin may represent a potential novel molecular therapeutic target in chondrosarcoma metastasis.

miR-519d-mediated downregulation of STAT3 suppresses breast cancer progression

MicroRNAs (miRNAs) play important roles in the the gene regulation of carcinogenesis including breast cancer. miR‑519d has been studied in various types of cancer, but its role in breast cancer remains unclear. In the present study, we investigated the expression and biological function of miR-519d in breast cancer. Using quantitative RT-PCR (RT-qPCR) analysis, we analyzed the expression of miR-519d in breast cancer tissues and cell lines. It was shown that miR-519d expression was decreased in cancer tissues and cell lines compared with their controls. Overexpression of miR-519d inhibited cell proliferation and invasion, and induced apoptosis of breast cancer cells. Signal transducer and activator of transcription 3 (STAT3) was predicted as a target gene of miR-519d and it was verified by the luciferase reporter assay. Additionally, STAT3 mRNA and protein expression levels were downregulated in the cells with miR-519d overexpression as determined by RT-qPCR and western blotting. Taken together, the results indicated that miR-519d functions as a tumor suppressor in breast cancer by suppressing STAT3 expression.

Fructus phyllanthi tannin fraction induces apoptosis and inhibits migration and invasion of human lung squamous carcinoma cells in vitro via MAPK/MMP pathways

AIM

Fructus phyllanthi tannin fraction (PTF) from the traditional Tibetan medicine Fructus phyllanthi has been found to inhibit lung and liver carcinoma in mice. In this study we investigated the anticancer mechanisms of PTF in human lung squamous carcinoma cells in vitro.

METHODS

Human lung squamous carcinoma cell line (NCI-H1703), human large-cell lung cancer cell line (NCI-H460), human lung adenocarcinoma cell line (A549) and human fibrosarcoma cell line (HT1080) were tested. Cell viability was detected with MTT assay. Cell migration and invasion were assessed using a wound healing assay and a transwell chemotaxis chambers assay, respectively. Cell apoptosis was analyzed with flow cytometric analysis. The levels of apoptosis-related and metastasis-related proteins were detected by Western blot and immunofluorescence.

RESULTS

PTF dose-dependently inhibited the viability of the 3 human lung cancer cells. The IC50 values of PTF in inhibition of NCI-H1703, NCI-H460, and A549 cells were 33, 203, and 94 mg/L, respectively. PTF (15, 30, and 60 mg/L) dose-dependently induced apoptosis of NCI-H1703 cells. Treatment of NCI-H1703 and HT1080 cells with PTF significantly inhibited cell migration, and reduced the number of invasive cells through Matrigel. Furthermore, PTF dose-dependently down-regulated the expression of phosphor-ERK1/2, MMP-2 and MMP-9, up-regulated the expression of phosphor-JNK, but had no significant effect on the expression of ERK1/2 or JNK.

CONCLUSION

PTF induces cell apoptosis and inhibits the migration and invasion of NCI-H1703 cells by decreasing MPPs expression through regulation of the MAPK pathway.

Up-Regulation of MiR-300 Promotes Proliferation and Invasion of Osteosarcoma by Targeting BRD7

Increasing reports suggest that deregulated microRNAs (miRNAs) might provide novel therapeutic targets for cancers. However, the expression and function of miR-300 in osteosarcoma is still unknown. In our study, we found that the expression of miR-300 was up-regulated in osteosarcoma tissues and cells compared with paired adjacent non-tumor bone tissues and osteoblastic cells using RT-qPCR. The enforced expression of miR-300 could promote cell proliferation, invasion and epithelial-mesenchymal transition (EMT). Moreover, we identified that bromodomain-containing protein 7 (BRD7), a new tumor suppressor gene, was a direct target of miR-300. Ectopic expression of BRD7 could significantly inhibit miR-300-promoted proliferation, invasion and EMT. Therefore, our results identify an important role for miR-300 in osteosarcoma through regulating BRD7 expression.

Integrated Stable Isotope Labeling by Amino Acids in Cell Culture (SILAC) and Isobaric Tags for Relative and Absolute Quantitation (iTRAQ) Quantitative Proteomic Analysis Identifies Galectin-1 as a Potential Biomarker for Predicting Sorafenib Resistance in Liver Cancer

Sorafenib has become the standard therapy for patients with advanced hepatocellular carcinoma (HCC). Unfortunately, most patients eventually develop acquired resistance. Therefore, it is important to identify potential biomarkers that could predict the efficacy of sorafenib. To identify target proteins associated with the development of sorafenib resistance, we applied stable isotope labelling with amino acids in cell culture (SILAC)-based quantitative proteomic approach to analyze differences in protein expression levels between parental HuH-7 and sorafenib-acquired resistance HuH-7 (HuH-7(R)) cells in vitro, combined with an isobaric tags for relative and absolute quantitation (iTRAQ) quantitative analysis of HuH-7 and HuH-7(R) tumors in vivo. In total, 2,450 quantified proteins were identified in common in SILAC and iTRAQ experiments, with 81 showing increased expression (>2.0-fold) with sorafenib resistance and 75 showing decreased expression (<0.5-fold). In silico analyses of these differentially expressed proteins predicted that 10 proteins were related to cancer with involvements in cell adhesion, migration, and invasion. Knockdown of one of these candidate proteins, galectin-1, decreased cell proliferation and metastasis in HuH-7(R) cells and restored sensitivity to sorafenib. We verified galectin-1 as a predictive marker of sorafenib resistance and a downstream target of the AKT/mTOR/HIF-1α signaling pathway. In addition, increased galectin-1 expression in HCC patients' serum was associated with poor tumor control and low response rate. We also found that a high serum galectin-1 level was an independent factor associated with poor progression-free survival and overall survival. In conclusion, these results suggest that galectin-1 is a possible biomarker for predicting the response of HCC patients to treatment with sorafenib. As such, it may assist in the stratification of HCC and help direct personalized therapy.

MiR-519d-3p suppresses invasion and migration of trophoblast cells via targeting MMP-2

Our study was approved by the Medical Ethics Committee of Tang Du Hospital, Fourth Military Medical University and complied strictly with national ethical guidelines. Preeclampsia (PE) is a specific clinical disorder characterized by gestational hypertension and proteinuria and is a leading cause of maternal and perinatal mortality worldwide. The miR-519d-3p is upregulated in the maternal plasma of patients with PE which indicates a possible association between this microRNA and the pathogenesis of PE. No studies to date have addressed the effect of miR-519d-3p on the invasion and migration of trophoblast cells. In our study, we found that miR-519d-3p expression was elevated in placental samples from patients with PE. In vitro, overexpression of miR-519d-3p significantly inhibited trophoblast cell migration and invasion, whereas transfection of a miR-519d-3p inhibitor enhanced trophoblast cell migration and invasion. Luciferase assays confirmed that matrix metalloproteinase-2 (MMP-2) is a direct target of miR-519d-3p. Quantitative real-time PCR and western blot assays showed that overexpression of miR-519d-3p downregulated MMP-2 mRNA and protein expression. Knockdown of MMP-2 using a siRNA attenuated the increased trophoblast migration and invasion promoted by the miR-519d-3p inhibitor. In placentas from patients with PE or normal pregnancies, a negative correlation between the expression of MMP-2 and miR-519d-3p was observed using the Pearson correlation and linear regression analysis. Our present findings suggest that upregulation of miR-519d-3p may contribute to the development of PE by inhibiting trophoblast cell migration and invasion via targeting MMP-2; miR-519d-3p may represent a potential predictive and therapeutic target for PE.

MicroRNA-26b inhibits metastasis of osteosarcoma via targeting CTGF and Smad1

Downregulation of miR-26b has been found in various cancers, but it has never been investigated in osteosarcoma. In this study, we demonstrated downregulation of miR-26b in osteosarcoma tissues, negatively correlated with the expression of connective tissue growth factor (CTGF) and Smad1. Luciferase reporter assay confirmed the interaction of miR-26b with the 3' untranslated regions (UTRs) of CTGF and Smad1. Transfection of miR-26b in osteosarcoma cells suppressed the expression of CTGF and Smad1, suggesting CTGF and Smad1 as direct targets of miR-26b. Overexpression of miR-26b inhibited the migration of osteosarcoma cells, which was reversed by overexpression of CTGF or Smad1. Knockdown of CTGF by small interfering RNA (siRNA) interference blocked the activation of Smad1, ERK1/2, and MMP2, which was opposite to the overexpression of CTGF. Differently, Smad1 did not significantly affect CTGF level, but mediated ERK1/2 phosphorylation and MMP2 activation. Furthermore, miR-26b inhibited lung metastasis of osteosarcoma in vivo. Our data indicated that downregulation of miR-26b in osteosarcoma elevated the levels of CTGF and Smad1, facilitating osteosarcoma metastasis.

ClC-3 chloride channel modulates the proliferation and migration of osteosarcoma cells via AKT/GSK3β signaling pathway

In cultured human osteosarcoma (OS) cells, we recently demonstrated that insulin-like growth factors (IGF-1)-induced MG-63 and 143B human OS cells proliferation were consistent with increasing ClC-3 expression, and ClC-3 was up-regulated in cells with high metastatic potency. Blockade of ClC-3 greatly suppressed the phosphorylation activation of Akt/GSK3β. We also found that blockade of ClC-3 effectively down-regulated the expression of cyclin D1 and cyclin E, and caused activation of p27(KIP) and p21(CIP). The synthesized effects on these proteins which play a major role in cell cycle regulation bring about G0/G1 cell cycle arrest in MG-63 cells, and finally abrogate the cell proliferation. Besides, ClC-3 deletion attenuates OS cell migration via down-regulation the expression of MMP-2 and MMP-9. Such information suggests that ClC-3 might be a potential target for anti-OS.

CCL5/CCR5 axis induces vascular endothelial growth factor-mediated tumor angiogenesis in human osteosarcoma microenvironment

Chemokines modulate angiogenesis and metastasis that dictate cancer development in tumor microenvironment. Osteosarcoma is the most frequent bone tumor and is characterized by a high metastatic potential. Chemokine CCL5 (previously called RANTES) has been reported to facilitate tumor progression and metastasis. However, the crosstalk between chemokine CCL5 and vascular endothelial growth factor (VEGF) as well as tumor angiogenesis in human osteosarcoma microenvironment has not been well explored. In this study, we found that CCL5 increased VEGF expression and production in human osteosarcoma cells. The conditioned medium (CM) from CCL5-treated osteosarcoma cells significantly induced tube formation and migration of human endothelial progenitor cells. Pretreatment of cells with CCR5 antibody or transfection with CCR5 specific siRNA blocked CCL5-induced VEGF expression and angiogenesis. CCL5/CCR5 axis demonstrably activated protein kinase Cδ (PKCδ), c-Src and hypoxia-inducible factor-1 alpha (HIF-1α) signaling cascades to induce VEGF-dependent angiogenesis. Furthermore, knockdown of CCL5 suppressed VEGF expression and attenuated osteosarcoma CM-induced angiogenesis in vitro and in vivo. CCL5 knockdown dramatically abolished tumor growth and angiogenesis in the osteosarcoma xenograft animal model. Importantly, we demonstrated that the expression of CCL5 and VEGF were correlated with tumor stage according the immunohistochemistry analysis of human osteosarcoma tissues. Taken together, our findings provide evidence that CCL5/CCR5 axis promotes VEGF-dependent tumor angiogenesis in human osteosarcoma microenvironment through PKCδ/c-Src/HIF-1α signaling pathway. CCL5 may represent a potential therapeutic target against human osteosarcoma.