MicroRNA-135a acts as a putative tumor suppressor by directly targeting very low density lipoprotein receptor in human gallbladder cancer.

The precise functions and mechanisms of microRNAs (miR) in gallbladder cancer (GBC) remain elusive. In this study, we found that miR-135a-5p expression is often dampened and correlated with neoplasm histologic grade in GBC. MicroRNA-135a-5p introduction clearly inhibited GBC cell proliferation in vitro and in vivo. Moreover, very low density lipoprotein receptor (VLDLR), which is often upregulated in GBC tissues, was identified as a direct functional target of miR-135a-5p. Furthermore, the p38 MAPK pathway was proven to be involved in miR-135a-VLDLR downstream signaling. Together, these results suggested that the miR-135a-VLDLR-p38 axis may contribute to GBC cell proliferation.

Genome-wide screening reveals that miR-195 targets the TNF-α/NF-κB pathway by down-regulating IκB kinase alpha and TAB3 in hepatocellular carcinoma.

UNLABELLED: Nuclear factor kappa B (NF-κB) is an important factor linking inflammation and tumorigenesis. In this study we experimentally demonstrated through a high-throughput luciferase reporter screen that NF-κB signaling can be directly targeted by nearly 29 microRNAs (miRNAs). Many of these miRNAs can directly target NF-κB signaling nodes by binding to their 3' untranslated region (UTR). miR-195, a member of the miR-15 family, is frequently down-regulated in gastrointestinal cancers, especially in hepatocellular carcinoma (HCC). The expression level of miR-195 is inversely correlated with HCC tumor size. We further show that miR-195 suppresses cancer cell proliferation and migration in vitro and reduces tumorigenicity and metastasis in vivo. Additionally, miR-195 may exert its tumor suppressive function by decreasing the expression of multiple NF-κB downstream effectors by way of the direct targeting of IKKα and TAB3. CONCLUSION: Multiple miRNAs are involved in the NF-κB signaling pathway and miR-195 plays important inhibitory roles in cancer progression and may be a potential therapeutic target.

Genome-wide copy number analyses identified novel cancer genes in hepatocellular carcinoma.

UNLABELLED: A powerful way to identify driver genes with causal roles in carcinogenesis is to detect genomic regions that undergo frequent alterations in cancers. Here we identified 1,241 regions of somatic copy number alterations in 58 paired hepatocellular carcinoma (HCC) tumors and adjacent nontumor tissues using genome-wide single nucleotide polymorphism (SNP) 6.0 arrays. Subsequently, by integrating copy number profiles with gene expression signatures derived from the same HCC patients, we identified 362 differentially expressed genes within the aberrant regions. Among these, 20 candidate genes were chosen for further functional assessments. One novel tumor suppressor (tripartite motif-containing 35 [TRIM35]) and two putative oncogenes (hairy/enhancer-of-split related with YRPW motif 1 [HEY1] and small nuclear ribonucleoprotein polypeptide E [SNRPE]) were discovered by various in vitro and in vivo tumorigenicity experiments. Importantly, it was demonstrated that decreases of TRIM35 expression are a frequent event in HCC and the expression level of TRIM35 was negatively correlated with tumor size, histological grade, and serum alpha-fetoprotein concentration. CONCLUSION: These results showed that integration of genomic and transcriptional data offers powerful potential for identifying novel cancer genes in HCC pathogenesis.

Hypoxia-inducible microRNA-210 augments the metastatic potential of tumor cells by targeting vacuole membrane protein 1 in hepatocellular carcinoma.

UNLABELLED: As the "master" microRNA that is induced by hypoxia, miR-210 is involved in multiple processes in the hypoxia pathway. However, whether miR-210 mediates hypoxia-induced tumor cell metastasis still remains unclear. Here, we demonstrate that miR-210 is frequently up-regulated in hepatocellular carcinoma (HCC) samples and promotes the migration and invasion of HCC cells. Furthermore, miR-210 can be induced by hypoxia in HCC cells and mediates hypoxia-induced HCC cell metastasis. We identify vacuole membrane protein 1 (VMP1) as the direct and functional downstream target of miR-210; in addition, we show that its expression is negatively correlated with the expression of miR-210 in HCC. Intriguingly, VMP1 is reduced by hypoxia, and down-regulation of VMP1 by miR-210 mediates hypoxia-induced HCC cell metastasis. CONCLUSION: These findings extend our understanding of the function of miR-210 in the hypoxia pathway, and this newly identified hypoxia/miR-210/VMP1 pathway should facilitate the development of novel therapeutics against hypoxic tumor cells.

Sphingosine kinase 1 promotes tumour cell migration and invasion via the S1P/EDG1 axis in hepatocellular carcinoma.

BACKGROUND/AIMS: Sphingosine kinase 1 (SphK1), which phosphorylates sphingosine to sphingosine-1-phosphate (S1P), is overexpressed in various types of cancers, and may act as an oncogene in tumorigenesis. However, little is known about the precise role of the SphK1/S1P pathway in human liver cancer, especially regarding the metastasis of hepatocellular carcinoma (HCC). MATERIALS AND METHODS: The expression of SphK1 was detected by quantitative reverse-transcription PCR. In addition, transwell cell migration and invasion assay were carried out for functional analysis. Furthermore, the level of S1P was quantified by ELISA and Rac1/Cdc42 GTPase activation was assessed by western blot analysis. RESULTS: The levels of SphK1 mRNA are commonly up-regulated in HCC patients and human liver cancer cell migration and invasion can be promoted by the overexpression of SphK1. In addition, inhibition of SphK1 with either a SphK1 inhibitor or siRNA reduced human liver cancer cell migration and invasion. Furthermore, overexpression of SphK1 increased S1P levels, and the exogenous addition of S1P increased liver cell migration and invasion through the EDG1 receptor. DISCUSSION AND CONCLUSION: The results from this study provide strong evidence of a role for the SphK1/S1P/EDG1 pathway in liver metastasis, thus making it an attractive therapeutic target for the development of new anti-HCC drugs.

MicroRNA-423 promotes cell growth and regulates G(1)/S transition by targeting p21Cip1/Waf1 in hepatocellular carcinoma.

MicroRNAs (miRNAs) are small non-coding RNA molecules that are often located in genomic breakpoint regions and can act as oncogenes or tumor suppressor genes in human cancer. Our previous study showed that microRNA-423 (miR-423), which localized to the frequently amplified region of chromosome 17q11, was upregulated in hepatocellular carcinoma (HCC). However, the potential functions and exact mechanistic roles of miR-423 in hepatic carcinogenesis remain unknown. Here, we demonstrated that miR-423 significantly promotes cell growth and cell cycle progression at the G(1)/S transition in HCC cells. In particular, we found that miR-423-3p contributes to these effects, whereas miR-423-5p does not. Further studies revealed that p21Cip1/Waf1 is a downstream target of miR-423 in HCC cells, as miR-423 bound directly to its 3' untranslated region and reduced both the messenger RNA and protein levels of p21Cip1/Waf1. Moreover, enforced expression of p21Cip1/Waf1 abrogated miR-423-induced effects on HCC cell proliferation and cell cycle progression. These findings indicate that miR-423 exerts growth-promoting effects in hepatic carcinogenesis through the suppression of tumor suppressor p21Cip1/Waf1 expression. The results of this study define miR-423 as a new oncogenic miRNA in HCC.

MiR-525-3p enhances the migration and invasion of liver cancer cells by downregulating ZNF395.

Liver cancer is one of leading causes of cancer-related deaths. A deeper mechanistic understanding of liver cancer could lead to the development of more effective therapeutic strategies. In our previous work, we screened 646 miRNAs and identified 11 that regulate liver cancer cell migration. The current study shows that miR-525-3p is frequently up-regulated in liver cancer tissues, and enhanced expression of miR-525-3p can promote liver cancer cell migration and invasion. Zinc finger protein 395 (ZNF395) is the direct functional target gene for miR-525-3p, and it is frequently down-regulated in liver cancer tissues. High expression of ZNF395 can significantly inhibit while knockdown of ZNF395 expression can markedly enhance the migration and invasion of liver cancer cells, suggesting that ZNF395 suppresses metastasis in liver cancer. Down-regulation of ZNF395 can mediate miR-525-3p induced liver cancer cell migration and invasion. In conclusion, miR-525-3p promotes liver cancer cell migration and invasion by directly targeting ZNF395, and the fact that miR-525-3p and ZNF395 both play important roles in liver cancer progression makes them potential therapeutic targets.

Genome-wide screening identified that miR-134 acts as a metastasis suppressor by targeting integrin ß1 in hepatocellular carcinoma.

MicroRNAs (miRNAs) are small, single-stranded, non-coding RNAs that play pivotal roles in human cancer development and progression, such as tumor metastasis. Here, we identified the miRNAs that regulate hepatocellular carcinoma (HCC) cell migration by a high-throughput screening method using the classical wound-healing assay with time-lapse video microscopy and validation with a transwell migration assay. Eleven miRNAs (miR-134, -146b-3p, -188-3p, -525-3p, -661, -767-5p, -891a, -891b, -1244, -1247 and miR-1471) were found to promote or inhibit HCC cell migration. Further investigation revealed that miR-134 suppressed the invasion and metastasis of HCC cells in vitro and in vivo, and integrin beta 1 (ITGB1) was a direct and functional target gene of miR-134. Moreover, miR-134 inhibited the phosphorylation of focal adhesion kinase (FAK) and the activation of RhoA downstream of the ITGB1 pathway, thereby decreasing stress fiber formation and cell adhesion in HCC cells. In conclusion, we demonstrated that miR-134 is a novel metastasis suppressor in HCC and could be a potential therapeutic target for the treatment of HCC.

MicroRNA-26a acts as a tumor suppressor inhibiting gallbladder cancer cell proliferation by directly targeting HMGA2.

MicroRNAs (miRNAs) are a class of small, single-stranded, non-coding RNA molecules which can act as oncogenes or tumor suppressor genes in human cancer. However, the possible functions and mechanisms of miRNA action in gallbladder cancer (GBC) have not been elucidated. In the present study, it was found that miR-26a was often downregulated in GBC and the expression of miR-26a was associated with neoplasm histological grade. miR-26a significantly inhibited the proliferation of GBC cells based on the gain-of-function assays. Furthermore, we demonstrated that high mobility group AT-hook 2 (HMGA2) was a direct target of miR-26a. The results showed that HMGA2 mRNA levels and miR-26a levels were negatively correlated. In addition, we confirmed that reintroduction of HMGA2 antagonized the inhibition of miR-26a to GBC cell proliferation and all these effects were achieved through the cell cycle. Together, all these results suggest that miR-26a expression contributes to GBC proliferation by targeting HMGA2. miR-26a shows promise as a prognosis factor and therapeutic target of GBC patients.

microRNA-202-3p inhibits cell proliferation by targeting ADP-ribosylation factor-like 5A in human colorectal carcinoma.

PURPOSE: MicroRNAs (miRNA) that are strongly implicated in carcinogenesis have recently reshaped our understanding of the role of non-protein-coding RNAs. Here, we focused on the function and molecular mechanism of miR-202-3p and its potential clinical application in colorectal cancer. EXPERIMENTAL DESIGN: miR-202-3p expression was determined by quantitative reverse transcriptase PCR (qRT-PCR) in 94 colorectal cancer tissues and corresponding noncancerous tissues (NCT). Cell proliferation and colony formation assays in vitro and xenograft experiments in vivo were used to evaluate the effect of miR-202-3p on colorectal cancer cell proliferation. Luciferase assay and Western blot analysis were performed to validate the potential targets of miR-202-3p after the preliminary screening by online prediction and microarray analysis. The mRNA and protein levels of target genes were detected by qRT-PCR and immunohistochemical staining. The copy number of pre-miR-202 was measured by quantitative PCR. RESULTS: First, miR-202-3p was significantly downregulated in 46.7% colorectal cancer samples compared with NCTs. The overexpression of miR-202-3p inhibited colorectal cancer cell growth in vitro and repressed tumorigenesis in nude mice. Then, miR-202-3p downregulated ADP-ribosylation factor-like 5A (ARL5A) protein level by binding to its 3' untranslated region, and knockdown of ARL5A phenocopied the proliferation inhibition effect of miR-202-3p. Furthermore, both of ARL5A mRNA and protein levels were upregulated in colorectal cancer samples compared with NCTs and high ARL5A protein levels predicted a poor prognosis. CONCLUSIONS: miR-202-3p might function as a tumor suppressor in colorectal cancer, and ARL5A, the functional target of miR-202-3p in colorectal cancer, is a potential prognostic factor for colorectal cancer.

Suppression of Human Liver Cancer Cell Migration and Invasion via the GABAA Receptor.

OBJECTIVE: To investigate the roles of the γ-aminobutyric acid (GABA) in the metastasis of hepatocellular carcinoma (HCC) and to explore the potential of a novel therapeutic approach for the treatment of HCC. METHODS: The expression levels of GABA receptor subunit genes in various HCC cell lines and patients' tissues were detected by quantitative real-time polymerase chain reaction and Western blot analysis. Transwell cell migration and invasion assays were carried out for functional analysis. The effects of GABA on liver cancer cell cytoskeletal were determined by immunofluorescence staining. And the effects of GABA on HCC metastasis in nude mice were evaluated using an in vivo orthotopic model of liver cancer. RESULTS: The mRNA level of GABA receptor subunits varied between the primary hepatocellular carcinoma tissue and the adjacent non-tumor liver tissue. GABA inhibited human liver cancer cell migration and invasion via the ionotropic GABAA receptor as a result of the induction of liver cancer cell cytoskeletal reorganization. Pretreatment with GABA also significantly reduced intrahepatic liver metastasis and primary tumor formation in vivo. CONCLUSIONS: These findings introduce a potential and novel therapeutic approach for the treatment of cancer patients based on the modulation of the GABAergic system.

MicroRNA-550a acts as a pro-metastatic gene and directly targets cytoplasmic polyadenylation element-binding protein 4 in hepatocellular carcinoma.

MicroRNAs (miRNAs) are a class of small, non-coding RNA molecules that are often found at chromosomal breakpoints and play a vital role in human cancer. Our previous study found that miR-550a, a frequently amplified miRNA on 7p14.3, was upregulated in hepatocellular carcinoma (HCC). However, the possible functions and molecular mechanisms of miR-550a in HCC remain unknown. In this study, gain-of-function and loss-of-function assays revealed that miR-550a markedly promoted HCC cell migration and invasion. In addition, we discovered that cytoplasmic polyadenylation element binding protein 4 (CPEB4) was a potential target of miR-550a in HCC. Further analyses showed that knockdown of CPEB4 expression significantly facilitated HCC cell migration and invasion, which phenocopied the effects of miR-550a on HCC cells. Moreover, a decrease in CPEB4 expression mediated miR-550a-induced liver cancer cell migration and invasion. Interestingly, CPEB4 is frequently downregulated in HCC, and its expression levels correlate with the overall survival of HCC patients. Together, these results suggested that this newly identified miR-550a-CPEB4 axis may be involved in HCC cell metastasis. Moreover, the expression levels of CPEB4 could be used to predict outcomes in HCC patients. Our findings provide novel potential targets for HCC therapy and prognosis.

Magnesium lithospermate B decreases [Ca(2+)]i in endothelial cells by inhibiting K(+) currents.

Magnesium lithospermate B (MLB) is a hydrophilic active component of Salviae miltiorrhizae Radix. Studies have shown that MLB affected intracellular calcium ([Ca(2+)]i), but the underlying mechanism was unclear yet. The present work was aimed to investigate the underlying mechanism of MLB affecting [Ca(2+)]i in endothelial cells (ECs). Isolated mesentery arteries were employed to test the involvement of L-Ca(2+) channel. [Ca(2+)]i was measured in ECs loaded with Fluo-3. Membrane potential and membrane currents were recorded in ECs using patch-clamp techniques. Results showed that MLB did not inhibit Ca(2+) influx via L-Ca(2+) channel in isolated mesenteric arteries. However, MLB decreased [Ca(2+)]i in a concentration-dependent manner in ECs. MLB depolarized the membrane potential of ECs and inhibited K(+) currents. These results demonstrated that MLB decreased [Ca(2+)]i by inhibiting K(+) currents and depolarizing membrane potential in ECs.

MicroRNA-148a suppresses tumor cell invasion and metastasis by downregulating ROCK1 in gastric cancer.

PURPOSE: MicroRNAs (miRNA) have been documented playing a critical role in cancer development and progression. In this study, we investigate the role of miR-148a in gastric cancer metastasis. EXPERIMENTAL DESIGN: We examined miR-148a levels in 90 gastric cancer samples by qRT-PCR and analyzed the clinicopathologic significance of miR-148a expression. The gastric cancer cells stably expressing miRNA-148a were analyzed for migration and invasion assays in vitro and metastasis assays in vivo; the target genes of miR-148a were further explored. RESULTS: We found that miR-148a expression was suppressed by more than 4-fold in gastric cancer compared with their corresponding nontumorous tissues, and the downregulated miR-148a was significantly associated with tumor-node-metastasis (TNM) stage and lymph node-metastasis. Functional assays showed that overexpression of miR-148a suppressed gastric cancer cell migration and invasion in vitro and lung metastasis formation in vivo. In addition, overexpression of miR-148a in GC cells could reduce the mRNA and protein levels of ROCK1, whereas miR-148a silencing significantly increased ROCK1 expression. Luciferase assays confirmed that miR-148a could directly bind to the 2 sites of 3' untranslated region of ROCK1. Moreover, in gastric cancer tissues, we observed an inverse correlation between miR-148a and ROCK1 expression. Knockdown of ROCK1 significantly inhibited gastric cancer cell migration and invasion resembling that of miR-148a overexpression. We further found that ROCK1 was involved in miR-148a-induced suppression of gastric cancer cell migration and invasion. CONCLUSIONS: miR-148a functions as a tumor metastasis suppressor in gastric cancer, and downregulation of miR-148a contributes to gastric cancer lymph node-metastasis and progression. miR-148a may have a therapeutic potential to suppress gastric cancer metastasis.

OxLDL stimulates lipoprotein-associated phospholipase A2 expression in THP-1 monocytes via PI3K and p38 MAPK pathways.

AIMS: Lipoprotein-associated phospholipase A2 (lp-PLA2) has been detected in human and rabbit atherosclerotic lesions, where it co-localizes with its substrate, oxidized LDL (oxLDL). Here, we investigated whether oxLDL may exert a regulatory effect on lp-PLA2 expression. METHODS AND RESULTS: Using human monocytic THP-1 cells as a model system, we found that oxLDL up-regulated the expression of lp-PLA2 while another substrate of the enzyme, platelet activating factor, had no such effect. The up-regulatory effect of oxLDL could be conferred by its oxidized phospholipids (oxPCs, the exact substrates of lp-PLA2), but not their hydrolyzed products, lysophosphatidylcholines (lysoPCs). OxLDL induced the activation of p38 mitogen-activating protein kinase (MAPK) through phosphatidylinositol 3-kinase (PI3K). Inhibition of either PI3K or p38 MAPK completely blocked oxLDL-induced lp-PLA2 expression. In addition, inhibition of lp-PLA2 activity in the conditioned medium significantly decreased lipid accumulation in macrophages as detected by oil red staining. CONCLUSION: The present study shows that oxLDL, and more specifically its unhydrolyzed oxidized phospholipids, can up-regulate lp-PLA2 expression in monocytes through the PI3K and p38 MAPK pathway. In turn, lp-PLA2 promotes lipoprotein uptake in macrophages. Our results uncover a new link between oxLDL and lp-PLA2, and may provide insight into this interaction in the context of atherosclerosis.

Prevention of lipopolysaccharide-induced injury by 3,5-dicaffeoylquinic acid in endothelial cells.

AIM: To investigate the effect of 3,5-dicaffeoylquinic acid (3,5-diCQA) on lipopolysaccharide (LPS)-induced injury in human dermal microvascular endothelial cells (HMEC-1). METHODS: The anti-oxidant effect was detected using the malondialdehyde (MDA) assay in a rat liver microsome model of lipid peroxidation. Cell viability was analyzed using the 3-(4,5-dimethylthiazol-2-yl)-2,5 diphenyltetrazolium bromide assay. Cell lipid peroxide injury was measured by lactate dehydrogenase (LDH) release. Apoptotic cells were detected by flow cytometry, and confirmed by DNA fragmentation analysis. Caspase-3 activity was measured using a specific assay kit. The level of intracellular reactive oxygen species (ROS) was determined by flow cytometry with a 2,7-dichlorodihydro-fluorescein diacetate fluorescence probe. RESULTS: The exposure of microsomes to ascorbate-Fe2+ resulted in lipoperoxidation according to an increase in the level of MDA. MDA formation decreased in a dose-dependent manner on treatment with 5, 10, or 50 micromol/L 3,5-diCQA. Treatment with LPS for 16 h resulted in a 60% decrease in cell viability and an increase in LDH release from 47.6% to 61.5%. DNA laddering was observed by agarose gel electrophoresis. The level of apoptotic cells peaked at 27% after treatment with LPS for 12 h. Following treatment with LPS for 12 h, intracellular ROS and caspase-3 activity increased. Pretreatment with 3,5-diCQA at 5, 10, or 50 micromol/L for 1 h attenuated LPS-mediated endothelial cell injury. The anti-apoptotic action of 3,5-diCQA was partially dependent on its capacity for anti-oxidation and the suppression of caspase-3 activity. CONCLUSION: 3,5-diCQA displays anti-oxidative and anti-apoptotic activity in HMEC-1 due to scavenging of intracellular ROS induced by LPS, and the suppression of caspase-3 activity.

Effects of scutellarin on PKCgamma in PC12 cell injury induced by oxygen and glucose deprivation.

AIM: To evaluate the neuroprotective effect and mechanisms of scutellarin (Scu) against PC12 cell injury after oxygen and glucose deprivation followed by reperfusion (OGD-Rep). METHODS: Undifferentiated rat pheochromocytoma PC12 cells, exposed to oxygen and glucose deprivation followed by reperfusion (OGD-Rep), used as an in vitro model of ischemia/reperfusion. Cell survival was evaluated by diphenyltetrazolium bromide (MTT) assay and the amount of LDH release was determined using assay kits. [Ca2+](i) was monitored using a fluorescent Ca2+-sensitive dye Fura-2 acetoxymethyl ester. Cell apoptosis was detected by a DNA ladder and by flow cytometric detection. The expression of protein kinase C (PKC)gamma was determined using both RT-PCR and Western blotting. The translocation of PKCgamma was assayed by subcellular fractionation and Western blotting. RESULTS: OGD-Rep injury significantly elevated the level of LDH release, [Ca2+](i), mRNA expression and the translocation of PKCgamma compared in the PC12 cells with those of the normal group. Scu (10-100 micromol/L) exerted a protective effect against OGD-Rep injury by reducing LDH release, [Ca2+](i), the percent of apoptosis, and the translocation of PKCgamma. CONCLUSION: Scu inhibits the increase of [Ca2+](i) and the activation of PKCgamma, exerting protective effects against PC12 cell injury induced by OGD-Rep.