Mutual suppression of miR-125a and Lin28b in human hepatocellular carcinoma cells

The role of LIN28B in tumor progression and metastasis in solid tumor entities

LIN28B is an RNA-binding protein that targets a broad range of microRNAs and modulates their maturation and activity. Under normal conditions, LIN28B is exclusively expressed in embryogenic stem cells, blocking differentiation and promoting proliferation. In addition, it can play a role in epithelial-to-mesenchymal transition by repressing the biogenesis of let-7 microRNAs. In malignancies, LIN28B is frequently overexpressed, which is associated with increased tumor aggressiveness and metastatic properties. In this review, we discuss the molecular mechanisms of LIN28B in promoting tumor progression and metastasis in solid tumor entities and its potential use as a clinical therapeutic target and biomarker.

MiR-125a-5p inhibits cell proliferation, cell cycle progression, and migration while promoting apoptosis in head and neck cancers by targeting ERBB3

OBJECTIVE

Head and neck cancer is one of the most common cancer types worldwide. MicroRNAs play a vital regulatory role in the occurrence and development of cancer. The objective of this study is to explore the mechanism of miR-125a-5p in the proliferation, migration and apoptosis of head and neck cancer cells and define its target genes.

METHODS

The effects of miR-125a-5p on head and neck cancer cells proliferation, cell cycle distribution, apoptosis and migration were evaluated by colony formation, BrdU assay, flow cytometry and transwell assays. The potential target gene of miR-125a-5p was determined by luciferase activity assay and western blot analysis.

RESULTS

In this study, overexpression of miR-125a-5p significantly inhibited the proliferation of head and neck cancer cells, whereas inhibition of miR-125a-5p enhanced their proliferation. BrdU assay and flow cytometry revealed that miR-125a-5p might inhibit the proliferation of cancer cells by causing cell cycle arrest. Cell apoptosis assay and Transwell assay indicated that miR-125a-5p induced cell apoptosis and inhibited cell migration of cancer cells. Other experiments confirmed that miR-125a-5p could significantly downregulate its expression by binding to ERBB3 to inhibit proliferation and ERBB3 could at least partially mediate the inhibition of miR-125a-5p on the proliferation of head and neck cancer cells.

CONCLUSION

The findings of this study suggested that the miR-125a-5p/ERBB3 axis might play a role in the proliferation, regulation of cell cycle, migration and apoptosis of head and neck cancer cells, potentially offering a new target for treatments of head and neck cancers.

miR-125b prevent the progression of esophageal squamous cell carcinoma through the p38-MAPK signaling pathway

Background

To examine the clinical significance of miR-125b in esophageal squamous cell carcinoma (ESCC) and to research the effect of miR-125b on the biological function of ESCC cells and the relevant underlying mechanism.

Methods

The expression of miR-125b in ESCC tissues and cell lines were discovered by RT-PCR assay. The interrelation between miR-125b expression and clinicopathological parameters and the forecasting of ESCC patients were analyzed. CCK-8 method and Transwell methods were used to detect the increased growth, shifting, and irruption of ESCC cells. Bioinformatics analysis was applied to forecast the possible target genes of miR-125b and verified through dual-luciferase reporter gene assay. After that, the expression of p38-MAPK mRNA and protein were found out by RT-PCR and Western blot.

Results

The expression of miR-125b was down-regulated in ESCC tissues and cell lines (P<0.05). And the expression of miR-125b was closely about tumor differentiation, TNM level, and lymph node metastasis in ESCC patients. The low miR-125b formulation was closely related to rough forecasting in ESCC patients. Large scale expression of miR-125b can effectively decrease the acceleration, shifting, and irrupting strengths of ESCC cells. Bioinformatics analysis showed p38-MAPK was forecasted to be a potential mark of miR-125b, which was confirmed by dual luciferase assay, and extreme expression of miR-125b can stop the expression of p38-MAPK mRNA and protein.

Conclusions

miR-125b is down-regulated in ESCC. Moreover, its expression level is significant concerning tumor progression and prognosis in patients with ESCC. MiR-125b can stop the high growth and shifting of ESCC cells having p38-MAPK at target.

Development and validation of an RNA binding protein-associated prognostic model for hepatocellular carcinoma

BACKGROUND

Hepatocellular carcinoma (HCC) is among the deadliest forms of cancer. While RNA-binding proteins (RBPs) have been shown to be key regulators of oncogenesis and tumor progression, their dysregulation in the context of HCC remains to be fully characterized.

METHODS

Data from the Cancer Genome Atlas - liver HCC (TCGA-LIHC) database were downloaded and analyzed in order to identify RBPs that were differentially expressed in HCC tumors relative to healthy normal tissues. Functional enrichment analyses of these RBPs were then conducted using the GO and KEGG databases to understand their mechanistic roles. Central hub RBPs associated with HCC patient prognosis were then detected through Cox regression analyses, and were incorporated into a prognostic model. The prognostic value of this model was then assessed through the use of Kaplan-Meier curves, time-related ROC analyses, univariate and multivariate Cox regression analyses, and nomograms. Lastly, the relationship between individual hub RBPs and HCC patient overall survival (OS) was evaluated using Kaplan-Meier curves. Finally, find protein-coding genes (PCGs) related to hub RBPs were used to construct a hub RBP-PCG co-expression network.

RESULTS

In total, we identified 81 RBPs that were differentially expressed in HCC tumors relative to healthy tissues (54 upregulated, 27 downregulated). Seven prognostically-relevant hub RBPs (SMG5, BOP1, LIN28B, RNF17, ANG, LARP1B, and NR0B1) were then used to generate a prognostic model, after which HCC patients were separated into high- and low-risk groups based upon resultant risk score values. In both the training and test datasets, we found that high-risk HCC patients exhibited decreased OS relative to low-risk patients, with time-dependent area under the ROC curve values of 0.801 and 0.676, respectively. This model thus exhibited good prognostic performance. We additionally generated a prognostic nomogram based upon these seven hub RBPs and found that four other genes were significantly correlated with OS.

CONCLUSION

We herein identified a seven RBP signature that can reliably be used to predict HCC patient OS, underscoring the prognostic relevance of these genes.

A Novel ceRNA Regulatory Network Involving the Long Non-Coding Antisense RNA SPACA6P-AS, miR-125a and its mRNA Targets in Hepatocarcinoma Cells

MicroRNAs (miRNA), and more recently long non-coding RNAs (lncRNA), are emerging as a driving force for hepatocellular carcinoma (HCC), one of the leading causes of cancer-related death. In this work, we investigated a possible RNA regulatory network involving two oncosuppressive miRNAs, miR-125a and let-7e, and a long non-coding antisense RNA, SPACA6P-AS (SP-AS), all transcribed from the same locus, with SP-AS in the opposite direction and thus carrying complementary sequences to the miRNAs. In vitro experiments validated the binding of the miRNAs to SP-AS. Then, the boosting of either the miRNAs or SP-AS levels demonstrated their reciprocal inhibition. In addition, overexpression of SP-AS resulted in a reduced silencing activity of miR-125a and let-7e toward their key oncogenic targets, i.e., Lin28b, MMP11, SIRT7, Zbtb7a, Cyclin D1, CDC25B, HMGA2, that resulted significantly upregulated. Finally, the analysis of 374 HCC samples in comparison to 50 normal liver tissues showed an upregulation of SP-AS and a reverse expression of miR-125a, not observed for let-7e; consistently, miR-125a oncogenic targets were upregulated. Overall, the data depict a novel competing endogenous RNA (ceRNA) network, ceRNET, whereby miR-125a can regulate the expression of SP-AS, which in turn regulates the miRNA by competing with the binding to the mRNA targets. We speculate that the unbalancing of any network component may contribute to hepatocarcinogenesis.

Proto-oncogene Zbtb7a represses miR-125a-5p transcription in hepatocellular carcinoma cells

Zbtb7a is a transcription factor whose dysfunction is correlated to the development of several types of cancer, including hepatocellular carcinoma (HCC). It generally acts as a repressor of transcription downregulating the expression of several target genes including oncosuppressors ARF and Rb. In this study, Zbtb7a was found to suppress the expression of miR-125a, an oncosuppressive miRNA that is often downregulated in HCC. This effect is mediated by the binding of the transcription factor to a regulatory sequence in the promoter of the transcription unit of miR-125a located 14 bp upstream of the transcription start site. Consistent with this observation, the analysis of 370 HCC samples showed an upregulation of Zbtb7a compared to 50 normal liver tissues and a reverse correlation with miR-125a expression. These data suggest that miR-125a may support the oncogenic potential of Zbtb7a.

miR-125 inhibits colorectal cancer proliferation and invasion by targeting TAZ

Colorectal cancer (CRC) is the third most common malignant tumor worldwide and is a serious threat to human health. MicroRNAs (miRNAs) play a key role in oncogenesis and cancer progression. MiRNA-125 (miR-125) is an important miRNA that is dysregulated in several kinds of cancers. Thus, we investigated the expression and effects of miR-125 and Transcriptional co-activator with PDZ-binding motif (TAZ) for a better understanding of the underlying mechanism of tumor progression in CRC, which may provide an emerging biomarker for diagnosis and treatment of CRC. We measured the expression levels of miR-125 in CRC tissues, adjacent tissues, and cell lines (e.g. HCT116, SW480, FHC) by quantitative real-time polymerase chain reaction (qRT-PCR). The effect of miR-125 on proliferation and invasion in CRC cells was detected by Cell Counting Kit-8 (CCK-8), clone formation assay, and transwell assay. Western blotting and qRT-PCR were used to investigate the expression of TAZ after knocking down miR-125 in HCT116 cells or overexpressing miR-125 in SW480 cells. MiR-125 was significantly down-regulated in CRC compared with pericarcinomatous tissue from 18 patients. An miR-125 inhibitor promoted CRC cell proliferation and invasion, while miR-125 mimic had the opposite effect. Moreover, we found that TAZ was an miR-125 target and the siRNA knockdown of TAZ could reverse the effect of the miR-125 inhibitor on proliferation and invasion in HCT116 cells. The present study shows that miR-125 suppresses CRC proliferation and invasion by targeting TAZ.

Lin28b is involved in curcumin-reversed paclitaxel chemoresistance and associated with poor prognosis in hepatocellular carcinoma

Chemoresistance remains a big challenge in hepatocellular carcinoma (HCC) treatment. Several studies indicated that RNA-binding protein Lin28B serves an oncogenic role in HCC, but its activity in HCC chemotherapy has never been assessed. In this study, we found that overexpression of Lin28B significantly increased the paclitaxel chemoresistance in two different HCC cells lines while silencing Lin28B reduced the chemoresistance in paclitaxel-resistance HCC cells. Curcumin, a natural anti-cancer agent, increased the sensitivity of HCC cells to paclitaxel through inhibiting NF-κB stimulated Lin28B expression both in vitro and in vivo. Furthermore, by analyzing TCGA (The Cancer Genome Atlas) LIHC (liver hepatocellular carcinoma) and GSE14520 databases, we found that Lin28B was highly upregulated in HCC tissue compared with that in normal tissue and associated with α‑fetoprotein levels, and that patients with Lin28B higher expression had a significant shorter overall survival time than those with Lin28B lower expression. Our data reveal that Lin28B may serve as a predictive biomarker and a treatment target to reverse HCC chemotherapy resistance in future clinical practice.

Antiproliferative Activity of microRNA-125a and its Molecular Targets

BACKGROUND

MicroRNA-125a is present in all animals with bilateral symmetry and displays a conserved nucleotide sequence with a section of 11 bases including the seed region that is identical in all considered species. It primarily downregulates the expression of LIN28, thereby promoting cell differentiation and larval phase transitions in nematodes, mammals and insects.

OBJECTIVE

In this review, we focus on the cellular control of miR-125a expression and its antiproliferative activity.

RESULTS

In mammalians, microRNA-125a is present in most adult organs and tissues in which it targets proteins involved in the mitogenic response, such as membrane receptors, intracellular signal transducers, or transcription factors, with the overall effect of inhibiting cell proliferation. Tissue levels of miR-125a generally raise during differentiation but it is often downregulated in cancers, e.g. colon, cervical, gastric, ovarian, lung, and breast cancers, osteosarcoma, neuroblastoma, glioblastoma, medulloblastoma, retinoblastoma and hepatocellular carcinoma.

CONCLUSION

The antiproliferative activity of miR-125a, demonstrated in many cell types, together with the notion that this miRNA is downregulated in several kinds of cancers, give a substantial support to the concept that miR-125a plays an oncosuppressive role.

MiR-128-3p increases sensitivity of hepatoma cells to oxaliplatin by targeting Lin28B

AIM

To investigate the effect of miR-128-3p on the sensitivity of hepatocellular carcinoma (HCC) cells to oxaliplatin, and explore the underlying mechanism.

METHODS

qRT-PCR was used to detect the expression of miR-128-3p and Lin28B in human liver cells (HL-7702) and human HCC cells (BEL-7402 and Hep-3B). BEL-7402 and Hep-3B cells as well as oxaliplatin resistant BEL-7402 and Hep-3B cells in logarithmic growth phase were randomly divided into a miR-128-3p mimic group (transfected with miR-128-3p mimics), a miR-NC group (untransfected cells), a Lin28B-3ʹ UTR WT group (psiCHECK2-Lin28B-3ʹUTR WT and miR-128-3p co-transfection), a Lin28B-3ʹ-UTR MUT (psiCHECK2-Lin28B-3ʹ UTR MUT and miR-NC co-transfection), a miR-128-3p + Lin28B group (miR-128-3p and Lin28B co-transfection), a si-Lin28B group (transfected with si-Lin28B) and a si-NC (transfected with silencing control). All cells were transfected via liposomes. The survival rate and viability of each group were detected by MTT assay, and the protein expression was detected by Western blot.

RESULTS

Compared with human hepatocytes, the expression of miR-128-3p in HCC cells (BEL-7402 and Hep-3B) was significantly decreased, and the expression of Lin28B was significantly increased. Overexpression of miR-128-3p or silencing Lin28B increased the sensitivity of HCC cells to oxaliplatin. Lin28B is a target of miR-128-3p, and overexpression of Lin28B could reverse the effect of miR-128-3p in increasing the sensitivity of HCC cells to oxaliplatin.

CONCLUSION

MiR-128-3p can increase the sensitivity of HCC cells to oxaliplatin possibly via a mechanism related to targeting Lin28B, suggesting that miR-128-3p could be used as a potential target for treatment of oxaliplatin resistance.