DNA Methylation-mediated Repression of miR-941 Enhances Lysine (K)-specific Demethylase 6B Expression in Hepatoma Cells

MicroRNAs (miRNAs) have been shown to play important roles in carcinogenesis. However, their underlying mechanisms of action in hepatocellular carcinoma (HCC) are poorly understood. Recent evidence suggests that epigenetic silencing of miRNAs through tumor suppression by CpG island hypermethylation may be a common hallmark of human tumors. Here, we demonstrated that miR-941 was significantly down-regulated in HCC tissues and cell lines and was generally hypermethylated in HCC. The overexpression of miR-941 suppressed in vitro cell proliferation, migration, and invasion and inhibited the metastasis of HCC cells in vivo. Furthermore, the histone demethylase KDM6B (lysine (K)-specific demethylase 6B) was identified as a direct target of miR-941 and was negatively regulated by miR-941. The ectopic expression of KDM6B abrogated the phenotypic changes induced by miR-941 in HCC cells. We demonstrated that miR-941 and KDM6B regulated the epithelial-mesenchymal transition process and affected cell migratory/invasive properties.     

miR-199a-3p targets CD44 and reduces proliferation of CD44 positive hepatocellular carcinoma cell lines

Previous work by us and others reported decreased expression of miR-199a-3p in hepatocellular carcinoma (HCC) tissues compared to adjacent benign tissue. We report here a significant reduction of miR-199a-3p expression in 7 HCC cell lines. To determine if miR-199a-3p has a tumor suppressive role, pre-miR-199a-3p oligonucleotides were transfected into the HCC cell lines. Pre-miR-199a-3p oligonucleotide reduced cell proliferation by approximately 60% compared to control oligonucleotide in only two cell lines (SNU449 and SNU423); the proliferation of the other 5 treated cell lines was similar to control oligonucleotide. A pre-miR-199a-3p oligonucleotide formulated with chemical modifications to enhance stability while preserving processing, reduced cell proliferation in SNU449 and SNU423 to the same extent as the commercially available pre-miR-199a-3p oligonucleotide. Furthermore, only the duplex miR-199a-3p oligonucleotide, and not the guide strand alone, was effective at reducing cell viability. Since a CD44 variant was essential for c-Met signaling [V. Orian-Rousseau, L. Chen, J.P. Sleeman, P. Herrlich, H. Ponta, CD44 is required for two consecutive steps in HGF/c-Met signaling, Genes Dev. 16 (2002) 3074-3086] and c-Met is a known miR-199a-3p target, we hypothesized that miR-199a-3p may also target CD44. Immunoblotting confirmed that only the two HCC lines that were sensitive to the effects of pre-miR-199a-3p were CD44+. Direct targeting of CD44 by miR-199a-3p was confirmed using luciferase reporter assays and immunoblotting. Transfection of miR-199a-3p into SNU449 cells reduced in vitro invasion and sensitized the cells to doxorubicin; both effects were enhanced when hyaluronic acid (HA) was added to the cell cultures. An inverse correlation between the expression of miR-199a-3p and CD44 protein was noted in primary HCC specimens. The ability of miR-199a-3p to selectively kill CD44+ HCC may be a useful targeted therapy for CD44+ HCC.     

miR-186 modulates hepatocellular carcinoma cell proliferation and mobility via targeting MCRS1-mediated Wnt/β-catenin signaling

Previous studies have revealed that miR-186 is involved in the pathogenesis of many malignancies. However, the role of miR-186 in hepatocellular carcinoma (HCC) carcinogenesis and its detailed mechanism are poorly understood. This study was to investigate the function of miR-186 in modulating HCC cell proliferation, cell cycle, migration, and invasion. We found that miR-186 was decreased in HCC tissues and cell lines. Loss-of-function experiments showed that reduction of miR-186 dramatically enhanced tumor cell proliferation and metastasis. Besides, miR-186 also participated in the modulation of the cell cycle. In addition, luciferase reporter assays and Western blot analysis showed that MCRS1 was a novel target of miR-186 in HCC cells. Notably, upregulation of miR-186 suppressed the nuclear β-catenin accumulation and blocked the activation of Wnt/β-catenin signaling in HCC cells. Forced MCRS1 expression abrogated the inhibitory effect of miR-186 on cell growth, metastasis and Wnt/β-catenin signaling in HCC cells. Our findings may provide new insight into the pathogenesis of HCC and miR-186/ MCRS1 might function as new therapeutic targets for HCC.     

Hepatitis B virus X protein mutant HBxΔ127 promotes proliferation of hepatoma cells through up-regulating miR-215 targeting PTPRT

The mutant of virus is a frequent event. Hepatitis B virus X protein (HBx) plays a vital role in the development of hepatocellular carcinoma (HCC). Therefore, the identification of potent mutant of HBx in hepatocarcinogenesis is significant. Previously, we identified a natural mutant of the HBx gene (termed HBxΔ127). Relative to wild type HBx, HBxΔ127 strongly enhanced cell proliferation and migration in HCC. In this study, we aim to explore the mechanism of HBxΔ127 in promotion of proliferation of hepatoma cells. Our data showed that both wild type HBx and HBxΔ127 could increase the expression of miR-215 in hepatoma HepG2 and H7402 cells. However, HBxΔ127 was able to significantly increase miR-215 expression relative to wild type HBx in the cells. We identified that protein tyrosine phosphatase, receptor type T (PTPRT) was one of the target genes of miR-215 through targeting 3′UTR of PTPRT mRNA. In function, miR-215 was able to promote the proliferation of hepatoma cells. Meanwhile anti-miR-215 could partially abolish the enhancement of cell proliferation mediated by HBxΔ127 in vitro. Knockdown of PTPRT by siRNA could distinctly suppress the decrease of cell proliferation mediated by anti-miR-215 in HepG2-XΔ127/H7402-XΔ127 cells. Moreover, we found that anti-miR-215 remarkably inhibited the tumor growth of hepatoma cells in nude mice. Collectively, relative to wild type HBx, HBxΔ127 strongly enhances proliferation of hepatoma cells through up-regulating miR-215 targeting PTPRT. Our finding provides new insights into the mechanism of HBx mutant HBxΔ127 in promotion of proliferation of hepatoma cells.     

MiR-199a Regulates Cell Proliferation and Survival by Targeting FZD7

A growing amount of evidence indicates that miRNAs are important regulators of multiple cellular processes and, when expressed aberrantly in different types of cancer such as hepatocellular carcinoma (HCC), play significant roles in tumorigenesis and progression. Aberrant expression of miR-199a-5p (also called miR-199a) was found to contribute to carcinogenesis in different types of cancer, including HCC. However, the precise molecular mechanism is not yet fully understood. The present study showed that miR-199a is frequently down-regulated in HCC tissues and cells. Importantly, lower expression of miR-199a was significantly correlated with the malignant potential and poor prognosis of HCC, and restoration of miR-199a in HCC cells led to inhibition of the cell proliferation and cell cycle in vitro and in vivo. Furthermore, Frizzled type 7 receptor (FZD7), the most important Wnt receptor involved in cancer development and progression, was identified as a functional target of miR-199a. In addition, these findings were further strengthened by results showing that expression of FZD7 was inversely correlated with miR-199a in both HCC tissues and cells and that over-expression of miR-199a could significantly down-regulate the expression of genes downstream of FZD7, including β-catenin, Jun, Cyclin D1 and Myc. In conclusion, these findings not only help us to better elucidate the molecular mechanisms of hepatocarcinogenesis from a fresh perspective but also provide a new theoretical basis to further investigate miR-199a as a potential biomarker and a promising approach for HCC treatment.     

miR-29c targets TNFAIP3, inhibits cell proliferation and induces apoptosis in hepatitis B virus-related hepatocellular carcinoma

Recent studies have revealed that microRNA-29c (miR-29c) is involved in a variety of biological processes including carcinogenesis. Here, we report that miR-29c was significantly downregulated in hepatitis B virus (HBV)-related hepatocellular carcinoma (HCC) cell lines as well as in clinical tissues compared with their corresponding controls. Tumor necrosis factor alpha-induced protein 3 (TNFAIP3), a key regulator in inflammation and immunity, was found to be inversely correlated with miR-29c levels and was identified as a target of miR-29c. Overexpression of miR-29c in HepG2.2.15 cells effectively suppressed TNFAIP3 expression and HBV DNA replication as well as inhibited cell proliferation and induced apoptosis. We conclude that miR-29c may play an important role as a tumor suppressive microRNA in the development and progression of HBV-related HCC by targeting TNFAIP3. Thus miR-29c and TNFAIP3 represent key diagnostic markers and potential therapeutic targets for the prevention and treatment of HBV infection.     

Modulatory efficacy of dieckol on xenobiotic-metabolizing enzymes,cell proliferation,apoptosis, invasion and angiogenesis during NDEA-induced rat hepatocarcinogenesis

Altered microRNA expression is associated with tumor proliferation, metastasis, and tumorigenesis. In this study, we studied the role of miR-3117 in hepatocellular carcinoma (HCC) cell proliferation and found that miR-3117 was upregulated in HCC tissues and cells. MTT assay, soft agar growth assay, BrdU assay, and cell cycle assay revealed that miR-3117 overexpression promoted HCC HepG2 cell proliferation and that knockdown of miR-3117 suppressed HepG2 proliferation. Mechanism analysis suggested PH domain and leucine-rich repeat protein phosphatase-like (PHLPPL) as the target of miR-3117. Luciferase reporter assay suggested that miR-3117 directly binds to the 3′UTR of PHLPPL. Double knockdown of miR-3117 and PHLPPL copied the phenotypes caused by miR-3117 overexpression, suggesting that miR-3117 contributes to the proliferation of HepG2 by targeting PHLPPL. Our study provided a target for HCC therapy.     

miRNA-148b suppresses hepatic cancer stem cell by targeting neuropilin-1

The existence of cancer stem cells (CSCs) is considered as a direct reason for the failure of clinic treatment in hepatocellular carcinoma (HCC). Growing evidences have demonstrated that miRNAs play an important role in regulation of stem cell proliferation, differentiation and self-renewal and their aberrances cause the formation of CSCs and eventually result in carcinogenesis. We recently identified miRNA-148b as one of the miRNAs specifically down-regulated in side population (SP) cells of PLC/PRF/5 cell line. However, it remains elusive how miRNA-148b regulates CSC properties in HCC. In the present study, we observed that overexpression or knockdown of miR-148b through lentiviral transfection could affect the proportion of SP cells as well as CSC-related gene expression in HCC cell lines. In addition, miR-148b blocking could stimulate cell proliferation, enhance chemosensitivity, as well as increase cell metastasis and angiogenesis in vitro. More importantly, miR-148b could significantly suppress tumorigenicity in vivo. Further studies revealed that Neuropilin-1 (NRP1), a transmembrane co-receptor involved in tumour initiation, metastasis and angiogenesis, might be the direct target of miRNA-148b. Taking together, our findings define that miR-148b might play a critical role in maintenance of SP cells with CSC properties by targeting NRP1 in HCC. It is the potential to develop a new strategy specifically targeting hepatic CSCs (HCSCs) through restoration of miR-148b expression in future therapy.     

MiR-103 regulates hepatocellular carcinoma growth by targeting AKAP12

AKAP12/Gravin (A kinase anchor protein 12) belongs to the group of A-kinase scaffold proteins and functions as a tumor suppressor in some human primary cancers. While AKAP12 is found consistently downregulated in hepatocellular carcinoma (HCC), its involvement in hepatocarcinogenesis has not been fully elucidated. We identified targeting sites for miR-103 in the 3′-untranslated region (3′-UTR) of AKAP12 by bioinformatic analysis and confirm their function by a luciferase reporter gene assay. We reveal miR-103 expression to be inversely correlated with AKAP12 in HCC tissue samples and show that overexpressed miR-103 promotes cell proliferation and inhibits apoptosis by downregulating AKAP12 expression in HCC cell lines. On the other hand, repression of miR-103 suppresses proliferation and promotes apoptosis in HCC cells by increasing AKAP12. In xenografted HCC tumors, overexpression of AKAP12 suppresses tumor growth whereas overexpression of miR-103 enhances tumor growth while repressing AKAP12. Since the activation of telomerase is crucial for cells to gain immortality and proliferation ability, we investigated whether AKAP12 expression affected telomerase activity in HCC cells. Both AKAP12 overexpression and protein kinase Cα (PKCα) inhibition prevent nuclear translocation and phosphorylation of TERT and reduce telomerase activity in HCC cells. These findings indicate that miR-103 potentially acts as an oncogene in HCC by inhibiting AKAP12 expression and raise the possibility that miR-103 increases telomerase activity by increasing PKCα activity. Thus, miR-103 may represent a new potential diagnostic and therapeutic target for HCC treatment.     

MicroRNA 122对肝癌细胞基因表达谱的影响

为研究microRNA（miR-122）对肝癌细胞Hep3B基因表达谱的影响,并探讨其在肝癌发过程中的可能作用,构建了miR-122稳定高表达的Hep3B细胞,利用基因表达谱芯片技术筛选得到和对照组细胞比较的差异表达基因.研究结果显示,2倍以上变化的差异表达基因有490个,其中上调的有345个,下调的有145个.这些基因中有16个与肿瘤发生相关,其它基因涉及细胞周期、信号转导、细胞凋亡和细胞增殖分化等众多生物学过程.这些结果提示,miR-122可能在肝癌发生的过程中发挥作用,并可能与这些差异表达基因密切相关.另外,还结合生物信息学方法,在下调表达的基因中预测了miR-122可能直接作用的靶基因.本研究初步探讨了miR-122在肝癌细胞中的生物学功能,为进一步研究miR-122在肝癌发生中的作用奠定了基础,同时也为miRNA的生物学功能及其作用机制的研究提供了一些参考.     

Long noncoding RNA DLX6-AS1 promotes liver cancer by increasing the expression of WEE1 via targeting miR-424-5p

Long noncoding RNAs (lncRNAs) played an important role in tumorigenesis and development of hepatocellular carcinoma (HCC). In this study, we first demonstrated that lncRNA DLX6 antisense RNA 1 (DLX6-AS1) was upregulated in cancer tissues and cells lines compared with normal adjacent and cell line. Knock-down DLX6-AS1 by transfection with small interfering RNA (siRNA) suppressed cell proliferation, migration, and invasion of HCC cells. Cell cycle analysis showed that cells transfected with siRNA were arrested in G0/G1 phase. Then, we performed dual-luciferase reporter assay and RNA immunoprecipitation (RIP) assay to show that DLX6-AS1 could bind with miR-424-5p. And cotransfection inhibitor of miR-424-5p with siRNA of DLX6-AS1 could abolish the inhibitory effect of siRNA of DLX6-AS1 on cell proliferation, migration, and invasion. Moreover, we further demonstrated that the oncogene WEE1 G2 checkpoint kinase (WEE1) was the target of miR-424-5p and expression levels of WEE1 were positive correlation with that of DLX6-AS1. Taken together, these results suggested that upregulated DLX6-AS1 promoted cell proliferation, migration, and invasion of HCC through increasing expression of WEE1 via targeting miR-424-5p.     

Overexpression of miR-623 suppresses progression of hepatocellular carcinoma via regulating the PI3K/Akt signaling pathway by targeting XRCC5

It has been reported that miR-623 is deregulated in lung adenocarcinoma and inhibits tumor growth and invasion. However, it is unclear whether miR-623 has a role in the progression of hepatocellular carcinoma (HCC). Herein, we found that miR-623 was significantly downregulated in HCC, and that its expression was related to poor clinical outcomes of patients with HCC. Upregulation of miR-623 decreased cell proliferation, viability, migration, and invasion and further promoted apoptosis in 7721, Huh7, and Bel-7402 cells. Moreover, we also observed that miR-623 regulated the phosphoinositide 3-kinase/protein kinase B (PI3K/Akt), Wnt/β-catenin, and extracellular regulated protein kinases/c-Jun N-terminal kinase (ERK/JNK) signaling pathways as well as the expression level of related proteins. Further, X-ray repair cross complementing 5 (XRCC5) was a direct target for miR-623, and the suppression of PI3K/Akt, Wnt/β-catenin, and ERK/JNK signaling pathways and cell proliferation and invasion abilities caused by miR-623 in HCC cells was significantly reversed by the upregulation of XRCC5. Collectively, our data suggested that miR-623 suppressed the progression of HCC by regulating the PI3K/Akt, Wnt/β-catenin, and ERK/JNK pathways by targeting XRCC5 in HCC in vitro, indicating that miR-623 may be a target for the therapy of HCC.     

Circ_0001178 regulates miR-382/VEGFA axis to facilitate hepatocellular carcinoma progression

Circular RNAs (circRNAs) have been reported to regulate the gene expression through sponging corresponding microRNAs in multiple malignant tumors, including hepatocellular carcinoma (HCC). Up to now, the effects of circ_0001178 in HCC are barely known. In our current work, we tested circ_0001178 expression in HCC tissues and HCC cells and found it was greatly elevated. Then, we evaluated the function of circ_0001178 on HCC cell proliferation. We found HepG2 and Huh-7 cell proliferation was repressed after circ_0001178 shRNA was infected into the cells. Moreover, flow cytometry evidenced that HepG2 and Huh-7 cell apoptosis was markedly triggered and cell cycle was arrested. Meanwhile, it was shown that HCC cell migration and invasion capacity were markedly inhibited by loss of circ_0001178. Knockdown of circ_0001178 restrained HCC tumor growth in vivo. Then, miR-382 was predicted and confirmed as the target of circ_0001178. Circ_0001178 was demonstrated to modulate miR-382 expression negatively. The effect of circ_0001178 on HCC tumor was rescued by miR-382 overexpression. Furthermore, vascular epithelial growth factor A (VEGFA) is identified in various cancers. Currently, VEGFA was proved to be the downstream target of miR-382. To conclude, this research revealed that circ_0001178 induced HCC progression via modulating miR-382 and VEGFA axis.