Signature microRNAs of nuclear Sm complex associated with breast cancer tumorigenesis

MBD1/HDAC3-miR-5701-FGFR2 axis promotes the development of gastric cancer

Gastric cancer (GC) remains one of the leading causes of cancer-related deaths worldwide due to the lack of specific biomarkers for the early diagnosis and universal accepted therapy for advanced GC. Lower levels of miR-5701 were found in the GC tissue from the online sequencing data and confirmed in the GC tissues and GC cell lines. Overexpression of miR-5701 inhibited the proliferation and migration of GC cells and promoted the apoptosis of these cells. Bioinformatics analyses and luciferase assay showed that miR-5701 targeted FGFR2, which acted as an oncogene in GC. Nude mice with GC cells overexpressing miR-5701 exhibited smaller tumor sizes and less lung metastases. The miR-5701 expression was directly, transcriptionally inhibited by MBD1 together with HDAC3 by binding together to form a complex. Knocked down MBD1 or HDAC3 increased the miR-5701 expression. These results indicated the potential use of exogenously administered miR-5701 or agents that elevated endogenous miR-5701 to inhibit GC, improving the prognosis of patients with GC.

miR-7/EGFR/MEGF9 axis regulates cartilage degradation in osteoarthritis via PI3K/AKT/mTOR signaling pathway

Osteoarthritis (OA) is a common degenerative disease in middle-aged and elderly people. Our previous study has proved that microRNA-7 (miR-7) exacerbated the OA process. This study was aimed to explore the downstream genes and mechanism regulated by miR-7 to affect OA. Multiple EGF-like-domains 9 (MEGF9) was the predicted target of miR-7 by databases. Luciferase report experiment results confirmed that MEGF9 could bind to miR-7. Among the 10 collected pairs of OA and healthy samples, the expression levels of miR-7 and MEGF9 were both up-regulated when compared with healthy subjects by qRT-PCR and immunohistochemistry (IHC). The increased MEGF9 levels were due to the interaction with epidermal growth factor receptor (EGFR) by co-immunoprecipitation. Evaluations found that upregulation of miR-7 or MEGF9 can increase the expression of EGFR, matrix metalloproteinase-13 (MMP-13) and a disintegrin like and metallopeptidase with thrombospondin type 1 motif 5 (ADAMTS-5), so as to aggravate cartilage degradation. In addition, this effect induced by miR-7/EGFR/MEGF9 axis was by activation of PI3K/AKT signaling. The IHC and western blot assay results on OA model mice also demonstrated that miR-7/EGFR/MEGF9 axis regulated cartilage degradation in vivo. In summary, miR-7/EGFR/MEGF9 axis may perform a crucial function in the regulation of OA, providing potential for OA treatment.

miR-5701 promoted apoptosis of clear cell renal cell carcinoma cells by targeting phosphodiesterase-1B

Increasing evidence has demonstrated that microRNAs play critical roles in malignant biological behaviors, including cancerogenesis, cancer progression and metastasis, through the regulation of target genes expression. As miR-5701 has recently been identified to play roles as tumor suppressor miRNA in the development of some kinds of cancers, in this study we sought to investigate the role of miR-5701 in clear cell renal cell carcinoma (ccRCC). Colony formation, cell apoptosis and proliferation assays were employed, and the results showed that miR-5701 inhibited proliferation and promoted apoptosis of ccRCC cells. Western blotting and dual-luciferase reporter assays were used to confirm that PDE1B is a new direct target of miR-5701. Furthermore, overexpression of PDE1B attenuated the effects of miR-5701, indicating that miR-5701 inhibited proliferation and promoted apoptosis of ccRCC cells via targeting PDE1B. Taken together, the data presented here indicate that t miR-5701 is a tumor suppressor in ccRCC and PDE1B is a new target of miR-5701.

Small non-coding RNA within the endogenous spliceosome and alternative splicing regulation

Splicing and alternative splicing (AS), which occur in the endogenous spliceosome, play major roles in regulating gene expression, and defects in them are involved in numerous human diseases including cancer. Although the mechanism of the splicing reaction is well understood, the regulation of AS remains to be elucidated. A group of essential regulatory factors in gene expression are small non-coding RNAs (sncRNA): e.g. microRNA, mainly known for their inhibitory role in translation in the cytoplasm; and small nucleolar RNA, known for their role in methylating non-coding RNA in the nucleolus. Here I highlight a new aspect of sncRNAs found within the endogenous spliceosome. Assembled in non-canonical complexes and through different base pairing than their canonical ones, spliceosomal sncRNAs can potentially target different RNAs. Examples of spliceosomal sncRNAs regulating AS, regulating gene expression, and acting in a quality control of AS are reviewed, suggesting novel functions for spliceosomal sncRNAs. This article is part of a Special Issue entitled: RNA structure and splicing regulation edited by Francisco Baralle, Ravindra Singh and Stefan Stamm.

Functional interactions between scaffold proteins, noncoding RNAs, and genome loci induce liquid-liquid phase separation as organizing principle for 3-dimensional nuclear architecture: implications in cancer

The eukaryotic cell nucleus consists of functionally specialized subcompartments. These nuclear subcompartments are biomolecular aggregates built of proteins, transcripts, and specific genome loci. The structure and function of each nuclear subcompartment are defined by the composition and dynamic interaction between these 3 components. The spatio-temporal localization of biochemical reactions into membraneless nuclear subcompartments can be achieved through liquid-liquid phase separation. Based on this organizing principle, nuclear subcompartments are droplet-like structures that adopt spherical shapes, flow, and fuse like liquids or gels. In the present review, we bring into the spotlight seminal works elucidating the functional interactions between scaffold proteins, noncoding RNAs, and genomic loci, thereby inducing liquid-liquid phase separation as an organizing principle for 3-dimensional nuclear architecture. We also discuss the implications in different cancer types as well as the potential use of this knowledge to develop novel therapeutic strategies against cancer.-Rubio, K., Dobersch, S., Barreto, G. Functional interactions between scaffold proteins, noncoding RNAs, and genome loci induce liquid-liquid phase separation as organizing principle for 3-dimensional nuclear architecture: implications in cancer.

Tumor suppressor miR-449a inhibits the development of gastric cancer via down-regulation of SGPL1

MicroRNAs (miRNAs) are small noncoding RNAs that are known to participate in the regulation of many physiological and pathological processes, which can indirectly influence the development of malignant behaviors. Numerous studies have demonstrated that miR-449a plays important roles in human carcinogenesis. However, its precise functional and regulatory roles remain unclear. In this study, we mainly explored the functional role of miR-449a in gastric cancer (GC). The expression levels of miR-449a in 98 cases of GC tissues and cell lines were determined by qRT-PCR. The possible mechanisms of miR-449a in GC cells were explored by fluorescence reporter assay. miR-449a expression was significantly lower in GC tissues compared to matched para-carcinoma tissues and was associated with tumor differentiation. Furthermore, in vitro knockdown of miR-449a by siRNA significantly inhibited MKN-28 cell proliferation, migration and invasion as well as tumorigenesis via inducing G0/G1 arrest of GC cells. In addition, we identified SGPL1 as a target of miR-449a and demonstrated that miR-449a regulated SGPL1 expression via binding its 3′-UTR region. The experiments indicated that miR-449a functions as a novel tumor suppressor in GC and its anti-oncogenic activity may involve its inhibition of the target gene SGPL1. These findings suggested that miR-449a may be a promising candidate for the development of antitumor drugs targeting GC.

MicroRNAs (miRNAs) are small noncoding RNAs that are known to participate in the regulation of many physiological and pathological processes, which can indirectly influence the development of malignant behaviors.