Small interfering RNA-directed knockdown of S100A4 decreases proliferation and invasiveness of osteosarcoma cells

Osterix promotes the migration and angiogenesis of breast cancer by upregulation of S100A4 expression

As a key transcription factor required for bone formation, osterix (OSX) has been reported to be overexpressed in various cancers, however, its roles in breast cancer progression remain poorly understood. In this study, we demonstrated that OSX was highly expressed in metastatic breast cancer cells. Moreover, it could upregulate the expression of S100 calcium binding protein A4 (S100A4) and potentiate breast cancer cell migration and tumor angiogenesis in vitro and in vivo. Importantly, inhibition of S100A4 impaired OSX-induced cell migration and capillary-like tube formation. Restored S100A4 expression rescued OSX-short hairpin RNA-suppressed cell migration and capillary-like tube formation. Moreover, the expression levels of OSX and S100A4 correlated significantly in human breast tumors. Our study suggested that OSX acts as an oncogenic driver in cell migration and tumor angiogenesis, and may serve as a potential therapeutic target for human breast cancer treatment.

MicroRNA-221 regulates osteosarcoma cell proliferation, apoptosis, migration, and invasion by targeting CDKN1B/p27

MicroRNAs (miRNAs, miR) are of critical importance in growth and metastasis of cancer cells; however, the underlying functions of miRNAs in osteosarcoma (OS) remain largely unknown. This study was aimed to elucidate the role of miR-221 in regulating the biological behavior of OS cells. The proliferation ability was examined by cell counting kit-8 (CCK-8) and cell cycle assay. The abilities of cell migration, invasion, and apoptosis were monitored by transwell assay and flow cytometry, respectively. The effect of miR-221 on cyclin-dependent kinase inhibitor 1B (CDKN1B) expression was evaluated by luciferase assays, real-time polymerase chain reaction, and Western blot analysis. We found that miR-221 was elevated in OS cell lines compared with the normal osteoblastic cell line. Transfection of the miR-221 inhibitor into MG63 and U-2OS cell lines obviously suppressed cell proliferation, migration, and invasion, which is accompanied with cell cycle arrest in G0/G1 phase. Furthermore, luciferase reporter assays indicated that CDKN1B is directly targeted by miR-221 in OS cells. Knockdown of CDKN1B inhibited the effects of miR-221 inhibitor, along with decreased Bax and caspase-3 and increased cyclin E, cyclin D1, Bcl-2, Snail, and Twist1 expression. The results suggested that miR-221 might act as a potentially useful target for treatment of OS.

Expression and Functional Analysis of Tumor-Related Factor S100A4 in Antler Stem Cells

Annual antler renewal is a stem cell-based epimorphic process driven by antler stem cells (ASCs) resident in antlerogenic periosteum (AP). Antlerogenic periosteal cells express a high level of S100A4, a metastasis-associated protein, which intrigued us to explore what role S100A4 could play in antler regeneration. The present study set out to investigate expression and effects of S100A4 in the ASCs and their progeny. The results showed that not only did cells from the AP express a high level of S100A4, but also the pedicle periosteum and the antler growth center. In the antler growth center, we found S100A4-positive cells were specifically located in blood vessel walls and in vascularized areas. In vitro, recombinant deer S100A4 protein stimulated the proliferation of the AP cells, promoted proliferation, migration and tube formation of human vascular endothelial cells, and enhanced migration of Hela cells, but not AP cells. These findings demonstrated that S100A4 in the ASCs may play a significant role in stimulating angiogenesis, proliferation, but not motility, of ASCs. Deer antlers offer a unique model to explore how rapid cell proliferation with a high level of S100A4 expression is elegantly regulated without becoming cancerous.

Downregulation of calbindin 1, a calcium-binding protein, reduces the proliferation of osteosarcoma cells

Osteosarcoma is the most common type of primary malignant bone tumor and has a high propensity to metastasize to the lungs and bones. Calbindin 1 (CALB1) is a constituent Ca2+ binding protein, which can prevent apoptotic death in several cell types induced through various pro-apoptotic signaling pathways. To investigate whether CALB1 is implicated in the tumor growth of human osteosarcoma, two different short hairpin RNAs (shRNAs) against CALB1 were used for CALB1-knockdown in osteosarcoma U2OS cells. The U2OS cells were divided into three groups: Two groups with CALB1 knockdown (CALB1-shRNA 1 and CALB1-shRNA 2) and one control group (Con-shRNA). Reverse transcription-quantitative polymerase chain reaction and western blot analysis confirmed that the CALB1-shRNA 1- and 2-infected cells exhibited significantly lower levels of CALB1 gene and protein expression compared with the Con-shRNA group. The proliferation and colony formation abilities were significantly inhibited in CALB1-deficient U2OS cells compared with the control, as measured using an MTT assay and crystal violet staining. Flow cytometry revealed that the number of CALB1-shRNA 2-injected cells was increased in the G0/G1 and G2/M phases, but decreased in the S phase, compared with the control group. The assessment of apoptosis and necrosis using Annexin V/7-aminoactinomycin D demonstrated that there was a significantly higher percentage of necrotic, early apoptotic, and late apoptotic cells, but a significantly lower percentage of viable cells in U2OS cells with CALB1-knockdown compared with the control group. In conclusion, CALB1 contributes to protecting osteosarcoma cells from apoptosis and provides a potential novel target for gene therapy to treat patients with osteosarcoma.

Small interfering RNA targeting S100A4 sensitizes non-small-cell lung cancer cells (A549) to radiation treatment

Objective

This study aimed to investigate the impact of S100A4-small interfering RNA (S100A4-siRNA) on apoptosis and enhanced radiosensitivity in non-small-cell lung cancer (A549) cells. We also explored the mechanisms of radiosensitization and identified a new target to enhance radiosensitivity and gene therapy for non-small-cell lung cancer.

Methods

RNA interference is a powerful tool for gene silencing. In this study, we constructed an effective siRNA to knock down S100A4. A549 cells were randomly divided into three groups: blank, negative control, and S100A4-siRNA. To investigate the effect of S100A4-siRNA, the expression of S100A4, E-cadherin, and p53 proteins and their messenger RNA (mRNA) was detected by Western blot and quantitative real-time polymerase chain reaction. Transwell chambers were used to assess cell invasion. Cell cycle and apoptosis were analyzed by flow cytometry. Radiosensitivity was determined by colony formation ability.

Results

Our results demonstrate that S100A4-siRNA effectively silenced the S100A4 gene. When siRNA against S100A4 was used, S100A4 protein expression was downregulated, whereas the expressions of E-cadherin and p53 were upregulated. In addition, a clear reduction in S100A4 mRNA levels was noted compared with the blank and negative control groups, whereas E-cadherin and p53 mRNA levels increased. Transfection with S100A4-siRNA significantly reduced the invasiveness of A549 cells. S100A4 silencing induced immediate G2/M arrest in cell cycle studies and increased apoptosis rates in A549 cells. In clonogenic assays, we used a multitarget, single-hit model to detect radiosensitivity after S100A4 knockdown. All parameters (D0, Dq, α, β) indicated that the downregulation of S100A4 enhanced radiosensitivity in A549 cells. Furthermore, S100A4-siRNA upregulated p53 expression, suggesting that S100A4 may promote A549 cell proliferation, invasion, and metastasis by regulating the expression of other proteins. Therefore, siRNA-directed S100A4 knockdown may represent a viable clinical therapy for lung cancer.

Conclusion

S100A4 downregulation potentially enhances the sensitivity of human A549 cells to radiotherapy.

Tumor necrosis factor-α modulates epithelial mesenchymal transition mediators ZEB2 and S100A4 to promote cholangiocarcinoma progression

BACKGROUND

The epithelial-mesenchymal transition (EMT) process strongly contributes to cancer metastasis. This study was to investigate the alteration of EMT-related proteins (ZEB1, ZEB2 and S100A4) in cholangiocarcinoma (CCA) tissues. The effect of tumor necrosis factor-α (TNF-α) on the expression of those molecules in CCA cells was investigated.

METHODS

The quantitative reverse transcription-polymerase chain reaction (qRT-PCR) assay was used to quantify ZEB1, ZEB2 and S100A4 mRNA levels in 50 CCA tissues and related its expression to clinicopathological data. ZEB2 protein immunostaining was investigated in 165 CCA tissues. The effect of TNF-α on EMT-related CCA cell migration was evaluated using qRT-PCR, immunofluorescence and transwell migration assays.

RESULTS

ZEB2 and S100A4 mRNA levels were found to be higher in CCA tissues. High levels of S100A4 mRNA and ZEB2 protein were significantly associated with CCA metastasis (P = 0.04 and P = 0.03). Moreover, a trend toward statistical association was found with high levels of both ZEB2 mRNA and protein with shorter survival time (P = 0.10 and P = 0.19). In addition, TNF-α induced CCA cell migration by the induction of transforming growth factor-β (TGF-β) resulting in ZEB2 and S100A4 mRNA and protein activation.

CONCLUSIONS

These studies demonstrate that TNF-α plays crucial role in the progression of CCA by activating TGF-β signaling and the induction of ZEB2 and S100A4, EMT-related proteins expression.

Suberoylanilide hydroxamic acid, an inhibitor of histone deacetylase, suppresses vasculogenic mimicry and proliferation of highly aggressive pancreatic cancer PaTu8988 cells

BACKGROUND

Pancreatic cancer is one of the most aggressive human malignancies with a extremely low 5-year survival rate. Hence, the search for more effective anti-pancreatic cancer agents is urgent.

METHODS

PaTu8988 pancreatic cancer cells were treated with different concentrations of suberoylanilide hydroxamic acid (SAHA), cell survival, proliferation, migration and vasculogenic mimicry (VM) were analyzed. Associated signaling changes were also analyzed by RT-PCR and Western blots.

RESULTS

Here, we reported that SAHA, a histone deacetylase inhibitor (HDACi), exerted significant inhibitory efficiency against pancreatic cancer cell survival, proliferation, migration and VM. SAHA dose-dependently inhibited PaTu8988 pancreatic cancer cell growth with the IC-50 of 3.4 ± 0. 7 μM. Meanwhile, SAHA suppressed PaTu8988 cell cycle progression through inducing G2/M arrest, which was associated with cyclin-dependent kinase 1 (CDK-1)/cyclin-B1 degradation and p21/p27 upregulation. Further, SAHA induced both apoptotic and non-apoptotic death of PaTu8988 cells. Significantly, SAHA suppressed PaTu8988 cell in vitro migration and cell-dominant tube formation or VM, which was accompanied by semaphorin-4D (Sema-4D) and integrin-β5 down-regulation. Our evidences showed that Akt activation might be important for Sema-4D expression in PaTu8988 cells, and SAHA-induced Sema-4D down-regulation might be associated with Akt inhibition.

CONCLUSIONS

This study is among the first to report the VM formation in cultured human pancreatic cancer cells. And we provided strong evidence to suggest that SAHA executes significant anti-VM efficiency in the progressive pancreatic cancer cells. Thus, SAHA could be further investigated as a promising anti-pancreatic cancer agent.

Icaritin suppresses the proliferation of human osteosarcoma cells in vitro by increasing apoptosis and decreasing MMP expression

AIM

To explore whether icaritin, a prenylflavonoid derivative of the Chinese tonic herb Epimedium, could suppress the proliferation of human osteosarcoma cells in vitro, and to elucidate the mechanisms of the action.

METHODS

Human osteosarcoma SaOS2 cell line was used in the present study. The proliferation of the cells was examined using MTT assay and immunofluorescence DAPI staining. Cell motility was studied with the scratch assay. Cell apoptosis was determined by Annexin V-FITC and PI double staining using flow cytometry. Western blotting and RT-PCR were used to measure the expression of mRNAs and proteins in the cells.

RESULTS

Icaritin (5-15 μmol/L) suppressed the proliferation of SaOS2 cells in vitro in a dose-dependent manner. Furthermore, the cell motility was significantly decreased after exposure to icaritin. Moreover, icaritin (5 μmol/L) time-dependently induced the apoptosis of SaOS2 cells, markedly suppressed MMP-2 and MMP-9 expression, upregulated caspase-3 and caspase-9 expression, and increased the level of cleaved caspase-3 in the cells. Co-exposure to the caspase-3 inhibitor zVAD-fmk (10 μmol/L) compromised the icaritin-induced caspase-3 expression and apoptosis in SaOS2 cells.

CONCLUSION

Icaritin suppresses the proliferation of SaOS2 human osteosarcoma cells by increasing apoptosis and downregulating MMP expression.

Human osteosarcoma cells respond to sorafenib chemotherapy by downregulation of the tumor progression factors S100A4, CXCR4 and the oncogene FOS

Osteosarcoma is a rare but aggressive bone neoplasm in humans, which is commonly treated with surgery, classical chemotherapy and radiation. Sorafenib, an inhibitor of a number of kinases targeting the Raf/MEK/ERK pathway, is a promising new chemotherapeutic agent in human medicine that has been approved since 2006 for the therapy of renal cell carcinoma and since 2007 for the treatment of hepatocellular carcinoma. Here, we studied the antimetastatic potential of 4 µM of this multikinase inhibitor in a human osteosarcoma cell line. DNA microarray-based gene expression profiling detected 297 and 232 genes upregulated or downregulated at a threshold of >2-fold expression alteration (P<0.05) in the sorafenib-treated cells. Three genes (CXCR4, FOS and S100A4) that are involved in tumor progression were chosen for validation by quantitative PCR (qPCR) and protein expression analysis. The decrease in RNA expression detected by microarray profiling was confirmed by qPCR for all three genes (P<0.01). On the protein level, sorafenib-induced reduction of S100A4 was verified both by western blotting and immunohistochemistry. For CXCR4 and c-Fos, a reduced protein expression was shown by immunohistochemistry, for c-Fos also by immunoblotting. We conclude that sorafenib could serve as a potent chemotherapeutical agent by which to inhibit the metastatic progression of osteosarcomas.

Up-regulated isocitrate dehydrogenase 1 suppresses proliferation, migration and invasion in osteosarcoma: in vitro and in vivo

Very few studies have been reported the function of wild type IDH1 in tumor progress. Previously, we reported that IDH1 correlated with pathological grade and metastatic potential inversely in human osteosarcoma. Here, IDH1 was found lower expressed in osteosarcoma tissues than that of adjacent normal bone tissues. In addition, we observed in vitro anti-proliferation and pro-apoptosis effects of up-regulated IDH1 on osteosarcoma cell lines. The migration and invasion activity was also markedly reduced by IDH1 up-regulation. Unexpectedly, IDH1 up-regulation also suppressed tumor growth and metastasis in vivo. Therefore, IDH1 may represent a potential novel treatment and preventive strategy for osteosarcoma.

Systemic shRNA mediated knock down of S100A4 in colorectal cancer xenografted mice reduces metastasis formation

The metastasis-inducing protein S100A4 was found to be a prognostic indicator for the development of metachronous metastases. S100A4 expression levels correlate with the formation of human colorectal cancer metastases and shorter patients’ survival. Inhibition of S100A4 expression in patients might therefore result in decreased metastasis formation and prolonged survival. In the present study, we used shRNA expression plasmids to inhibit S100A4 expression in the colorectal cancer cell lines HCT116, SW620 and DLD-1. Cell lines with reduced S100A4 expression showed reduced cell migration and invasion in vitro. The knock-down of S100A4 expression also led to significantly diminished formation of liver metastases when intrasplenically transplanted in mice (P = 0.004). We then focused on the therapeutic potential of systemically applied shRNA expression plasmids acting on S100A4 via repeated hydrodynamics-based tail vein injection of plasmid DNA. Mice, intrasplenically transplanted with HCT116 cells and treated systemically with S100A4-shRNA plasmids, showed a decrease of S100A4 and MMP9 expression levels, resulting in significantly reduced liver metastases (P = 0.005). In summary, we show for the first time the intratumoral knock-down of S100A4 via systemic application of S100A4-shRNA plasmid DNA, which restricts metastasis formation in a xenografted mouse model of colorectal cancer.

Role of epigenetics in cancer initiation and progression

The epigenome which comprises DNA methylation, histone modifications, chromatin structures and non-coding RNAs controls gene expression patterns. In cancer cells, there are aberrant changes in the epigenome. The question in cancer epigenetics is that whether these changes are the cause of cell transformation, or rather the consequence of it. We will discuss the epigenetic phenomenon in cancer, as well as the recent interests in the epigenetic reprogramming events, and their implications in the cancer stem cell theory. We will also look at the progression of cancers as they become more aggressive, with focus on the role of epigenetics in tumor metastases exemplified with the urokinase plasminogen activator (uPA) system. Last but not least, with therapeutics intervention in mind, we will highlight the importance of balance in the design of epigenetic based anti-cancer therapeutic strategies.

S100A4 regulates motility and invasiveness of human esophageal squamous cell carcinoma through modulating the AKT/Slug signal pathway

The involvement of S100A4 in modulating invasiveness of esophageal squamous cell carcinoma (ESCC) cell lines was explored. It was shown that S100A4 expression is positively correlated with the degree of invasiveness in human ESCC cells. The S100A4-rich EC-1 cells displayed higher migratory and invasive cell behavior while ET-1 cells with low S100A4 expression levels displayed lower migratory and invasive cell behavior. S100A4 silencing by small interfering (siRNA) in EC-1 cells induced E-cadherin expression, and overexpression of S100A4 in a lowly invasive TE-1 cells suppressed E-cadherin expression. It is suggested that S100A4 silencing inhibit invasion via E-cadherin upregulation, and overexpression of S100A4 promote invasion via E-cadherin downregulation in ESCC cells. Compared with the vector-transfected cells, S100A4 silencing in EC-1 cells showed reduced ability of migration and invasiveness, and overexpression of S100A4 in TE-1 cells showed increased ability of migration and invasiveness via wound-healing and Transwell assay, and pseudometastatic model assay. Furthermore, re-expression of S100A4 could increase the invasive phenotypes in S100A4 siRNA transfected EC-1 cells, and S100A4 silencing could decrease the invasive phenotypes in S100A4 circular DNA (cDNA) transfected TE-1 cells. It was found that Slug is downregulated in S100A4 siRNA transfected EC-1 cells, and Slug is upregulated in S100A4 cDNA transfected TE-1 cells. It was also discovered S100A4 cDNA induced protein kinase B (AKT) phosphorylation at Serine-473(phospho-AKT [p-AKT]) levels, followed by the Slug upregulation, and S100A4 siRNA decreases the phospho-AKT levels, followed by the Slug downregulation. The data suggested that S100A4 could regulate migratory and invasive behavior of human ESCC cells through modulating AKT/Slug pathway.

S100A4 silencing blocks invasive ability of esophageal squamous cell carcinoma cells

AIM: To investigate a potential role of S100A4 in esophagus squamous cell carcinoma metastasis (ESCCs).

METHODS: Expression of S100A4 and E-cadherin were analyzed in frozen sections from ESCCs (metastasis, n = 28; non-metastasis, n = 20) by reverse transcription-polymerase chain reaction, quantitative polymerase chain reaction and immunohistochemistry. To explore the influence of S100A4 on esophageal cancer invasion and metastasis, S100A4 was overexpressed or silenced by S100A4 siRNA in TE-13 or Eca-109 cells in vitro and in vivo.

RESULTS: We found the mRNA and protein levels of S100A4 expression in ESCCs was significantly upregulated, and more importantly, that expression of S100A4 and E cadherin are strongly negatively correlated in patients who had metastasis. It was indicated that overexpression of S100A4 in TE-13 and Eca-109 cells downregulates the expression of E-cadherin, leading to increased cell migration in vitro, whereas knockdown of S100A4 inhibited cell migration and upregulation of E-cadherin expression. Moreover, the loss of cell metastatic potential was rescued by overexpression of E-cadherin completely. In addition, nude mice inoculated with S100A4 siRNA-transfected cells exhibited a significantly decreased invasion ability in vivo.

CONCLUSION: S100A4 may be involved in ESCC progression by regulate E-cadherin expression, vector-based RNA interference targeting S100A4 is a potential therapeutic method for human ESCC.

Regulation of breast cancer metastasis by Runx2 and estrogen signaling: the role of SNAI2

Introduction

In contrast to its role in breast cancer (BCa) initiation, estrogen signaling has a protective effect in later stages, where estrogen receptor (ER)α loss associates with aggressive metastatic disease. We asked whether the beneficial effect of estrogen signaling in late-stage BCa is attributable to the recently reported estrogen-mediated antagonism of the pro-metastatic transcription factor Runx2.

Methods

MCF7/Rx2^dox breast cancer cells were engineered with a lentivirus expressing Runx2 in response to doxycycline (dox). Cells treated with dox and/or estradiol (E2) were subjected to genome-wide expression profiling, RT-qPCR analysis of specific genes, and Matrigel™ invasion assays. Knockdown of genes of interest was performed using lentiviruses expressing appropriate shRNAs, either constitutively or in response to dox. Gene expression in BCa tumors was investigated using a cohort of 557 patients compiled from publicly available datasets. Association of gene expression with clinical metastasis was assessed by dichotomizing patients into those expressing genes of interest at either high or low levels, and comparing the respective Kaplan-Meier curves of metastasis-free survival.

Results

Runx2 induced epithelial-mesenchymal transition (EMT) evidenced by acquisition of a fibroblastic morphology, decreased expression of E-cadherin, increased expression of vimentin and invasiveness. Runx2 stimulated SNAI2 expression in a WNT- and transforming growth factor (TGF)β-dependent manner, and knockdown of SNAI2 abrogated the pro-metastatic activities of Runx2. E2 antagonized the pro-metastatic activities of Runx2, including SNAI2 upregulation. In primary BCa tumors, Runx2 activity, SNAI2 expression, and metastasis were positively correlated, and SNAI2 expression was negatively correlated with ERα. However, the negative correlation between SNAI2 and ERα in bone-seeking BCa cells was weaker than the respective negative correlation in tumors seeking lung. Furthermore, the absence of ERα in primary tumors was associated with lung- and brain- but not with bone metastasis, and tumor biopsies from bone metastatic sites displayed the unusual combination of high Runx2/SNAI2 and high ERα expression.

Conclusions

E2 antagonizes Runx2-induced EMT and invasiveness of BCa cells, partly through attenuating expression of SNAI2, a Runx2 target required for mediating its pro-metastatic property. That ERα loss promotes non-osseous metastasis by unleashing Runx2/SNAI2 is supported by the negative correlation observed in corresponding tumors. Unknown mechanisms in bone-seeking BCa allow high Runx2/SNAI2 expression despite high ERα level

Stable knockdown of S100A4 suppresses cell migration and metastasis of osteosarcoma

S100A4, a 10-12 kDa calcium-binding protein, plays functional roles in tumor progression and metastasis. The present study aimed to investigate the function of S100A4 in osteosarcoma (OS) metastasis, using a loss-of-function approach. Our previous expression profiling analysis revealed that S100a4 was preferentially expressed in the highly metastatic mouse OS cell line, LM8. Introducing a short hairpin ribonucleic acid (shRNA) targeting S100a4 using a newly established vector containing insulators and transposons, we established stable LM8 subclones with almost 100% silencing of endogenous S100a4 protein. These transfectants showed a significant suppression of cell migration in vitro as well as a marked reduction in their ability to colonize the lung and form pulmonary metastases in vivo following intravenous inoculation, whereas there was no significant change in cell proliferation or cell attachment to fibronectin, laminin, and type I collagen. Expression and phosphorylation of ezrin, an emerging OS metastasis-associated factor, and expression of MMPs, remained the same in S100a4-shRNA clones. In 61 human OS, immunohistochemical analysis showed that lesional cells in 85.2% samples expressed S100A4 protein, and the immunoreactivity was primarily cytoplasmic, but it also showed occasional nuclear localization. Chondroblastic and osteoblastic OS subtypes expressed more S100A4 than fibroblastic subtypes. The causative role of S100A4 in OS lung metastasis shown in the murine xenograft model, together with the high proportion of primary human OS expressing S100A4, suggest that S100A4 protein represents an important potential target for future OS therapy.