MiR-342-3p inhibits LCSC oncogenicity and cell stemness through HDAC7/PTEN axis

lncRNA SNHG9 enhances liver cancer stem cell self-renewal and tumorigenicity by negatively regulating PTEN expression via recruiting EZH2

Liver cancer stem cell (CSC) self-renewal and tumorigenesis are important causes of hepatocellular carcinoma (HCC) recurrence. We purposed to investigate the function of long noncoding RNA small nucleolar RNA host gene 9 (SNHG9) in liver CSC self-renewal and tumorigenesis in this study. Flow cytometry was carried out to separate CD133+ Populations and CD133- Populations from HCC cell lines. A combination of CD133+ cells and Matrigel matrix was subcutaneously injected to create the NOD-SCID mouse xenograft tumor model. Colony formation test and spheroids formation assay were carried out to clarify the impact of SNHG9 on the self-renewal of liver CSCs. RNA immunoprecipitation, RNA-pull down, and chromatin immunoprecipitation were performed on CD133+ cells to elucidate the mechanism of SNHG9 regulating PTEN expression. We found that SNHG9 was highly expressed in HCC clinical samples, HCC cells, and CD133+ cells. In vitro, interference with SNHG9 prevented the formation of colonies and spheroids in liver CSC cells and primary HCC cells. In vivo, interference with SNHG9 reduced the tumor volume and weight. SNHG9 could bind to EZH2, and SNHG9 interference suppressed EZH2 recruitment and H3K27me3 levels in the PTEN promoter region. In addition, SNHG9 inhibition promoted PTEN expression while having little impact on EZH2 levels. Interference with SNHG9 inhibited liver CSC self-renewal and tumorigenesis by up-regulating PTEN levels. In conclusion, by binding to EZH2, SNHG9 down-regulated PTEN levels, promoting liver CSC self-renewal and tumor formation, and exacerbating HCC progression.

Tenogenic differentiation of human tendon-derived stem cells induced by long non-coding RNA LINCMD1 via miR-342-3p/EGR1 axis

BACKGROUND

Tendon-derived stem cells (TDSCs) are proposed as a potential cell-seed for the treatment of tendon injury due to their tenogenic differentiation potential. In this work, we defined the action of long non-coding RNA (lncRNA) muscle differentiation 1 (LINCMD1) in tenogenic differentiation of human TDSCs (hTDSCs).

METHODS

Quantitative real-time PCR (qRT-PCR) was used to assess the levels of LINCMD1, microRNA (miR)-342-3p, and early growth response-1 (EGR1) mRNA. Cell proliferation was detected by the XTT colorimetric assay. Protein expression was quantified by western blot. hTDSCs were grown in an osteogenic medium to induce osteogenic differentiation, and the extent of osteogenic differentiation was assessed by Alizarin Red Staining (ARS). The activity of alkaline phosphatase (ALP) was measured by the ALP Activity Assay Kit. Dual-luciferase reporter and RNA immunoprecipitation (RIP) assays were used to evaluate the direct relationship between miR-342-3p and LINCMD1 or EGR1.

RESULTS

Our results showed that enforced expression of LINCMD1 or suppression of miR-342-3p accelerated the proliferation and tenogenic differentiation and reduced osteogenic differentiation of hTDSCs. LINCMD1 regulated miR-342-3p expression by binding to miR-342-3p. EGR1 was identified as a direct and functional target of miR-342-3p, and knockdown of EGR1 reversed the effects of miR-342-3p suppression on cell proliferation and tenogenic and osteogenic differentiation. Furthermore, the miR-342-3p/EGR1 axis mediated the regulation of LINCMD1 on hTDSC proliferation and tenogenic and osteogenic differentiation.

CONCLUSION

Our study suggests the induction of LINCMD1 in tenogenic differentiation of hTDSCs through miR-342-3p/EGR1 axis.

miR-342-3p Inhibits Acute Myeloid Leukemia Progression by Targeting SOX12

Background

It is well known that microRNAs (miRNAs) interfere with the progression of various human malignancies. This article is aimed at exploring the regulating role of miR-342-3p in acute myeloid leukemia (AML) and its mechanism.

Methods

We used the Gene Expression Omnibus (GEO) database to determine miR-342-3p differential expression patterns in AML patients' plasma and cells as well as healthy individuals' plasma and T cells. Quantitative real-time PCR and Western blotting were performed for plasma and cell miR-342-3p and SRY-related high-mobility-group box (SOX12) expression quantification, and cell counting kit-8 assay and flow cytometry were used for the determination of AML cell growth, cycle, and apoptosis. A dual-luciferase reporter gene assay was further carried out to identify the targeted association between miR-342-3p and SOX12 mRNA 3′UTR after prediction by a bioinformatics website. Pearson's correlation analysis was performed to analyze the connection between miR-342-3p and SOX12 expressions. The LinkedOmics database was utilized to explore the downstream pathways in which SOX12 was enriched.

Results

Evidently downregulated plasma miR-342-3p and markedly elevated SOX12 were observed in AML patients versus healthy individuals. miR-342-3p mimics suppressed AML cell growth, enhanced apoptosis, and induced G0/G1 phase arrest; conversely, enhanced capacity of AML cells to proliferate, suppressed apoptosis, and accelerated cell cycle were observed after treatment with miR-342-3p inhibitors. SOX12 was confirmed as miR-342-3p's target gene. Overexpressing or knocking down SOX12 reversed miR-342-3p's impacts on AML cell growth, apoptosis, and cycle. Upregulated SOX12 was positively related to DNA replication and RNA polymerase signaling pathways.

Conclusion

miR-342-3p affects apoptosis of AML cells and their ability to proliferate via targeted regulation of SOX12.

The emerging roles of HDACs and their therapeutic implications in cancer

Deregulation of protein post-translational modifications is intensively involved in the etiology of diseases, including degenerative diseases, inflammatory injuries, and cancers. Acetylation is one of the most common post-translational modifications of proteins, and the acetylation levels are controlled by two mutually antagonistic enzyme families, histone acetyl transferases (HATs) and histone deacetylases (HDACs). HATs loosen the chromatin structure by neutralizing the positive charge of lysine residues of histones; whereas HDACs deacetylate certain histones, thus inhibiting gene transcription. Compared with HATs, HDACs have been more intensively studied, particularly regarding their clinical significance. HDACs extensively participate in the regulation of proliferation, migration, angiogenesis, immune escape, and therapeutic resistance of cancer cells, thus emerging as critical targets for clinical cancer therapy. Compared to HATs, inhibitors of HDAC have been clinically used for cancer treatment. Here, we enumerate and integratethe mechanisms of HDAC family members in tumorigenesis and cancer progression, and address the new and exciting therapeutic implications of single or combined HDAC inhibitor (HDACi) treatment.