LncRNA SNHG7 sponges miR-449a to promote pituitary adenomas progression

Regulation of long noncoding RNAs in the pathogenesis and clinical implications of pituitary adenomas

BACKGROUND

Pituitary adenoma (PA) is a type of tumor that develops in the sella turcica and is one of the most frequent intracranial tumors. It belongs to a type of adenoma derived from a single clone of cells in the pituitary gland. PA ranks third among all intracranial tumors, following only gliomas and meningioma. The average prevalence rate is approximately 15% at autopsy and 22.5% at radiological examinations.

OBJECTIVE AND SIGNIFICANCE

Most PAs are benign and non-invasive adenomas that can be removed surgically or controlled with medication. However, approximately 35% of them show invasion into nearby anatomical structures and cannot be completely resected. 0.1%~0.2% of PA cases eventually develop into pituitary carcinomas. Additionally, PA may cause severe morbidity due to mass effects and the disorder of pituitary hormone secretion. Therefore, there is an urgent need to clarify the pathological mechanism of PA, improve the accuracy of diagnosis, and develop targeted therapies.

RESEARCH STATUS

Although current knowledge about the pathogenesis of PA remains limited, epigenetic modulation of PA has been increasingly implicated. Long non-coding RNAs (lncRNAs) are known to regulate gene expression post-transcriptionally and exert substantial roles in the initiation, progression, or suppression of various tumors. Accumulating evidence has shown close relationships between lncRNA dysregulation and PA development.

CONCLUSIONS

This review highlights recent progress in the study of lncRNAs in PA pathogenesis and their potential as diagnostic/prognostic biomarkers or therapeutic targets for PA patients.

Non-coding RNAs and exosomal non-coding RNAs in pituitary adenoma

Pituitary adenoma (PA) is the third most common primary intracranial tumor in terms of overall disease incidence. Although they are benign tumors, they can have a variety of clinical symptoms, but are mostly asymptomatic, which often leads to diagnosis at an advanced stage when surgical intervention is ineffective. Earlier identification of PA could reduce morbidity and allow better clinical management of the affected patients. Non-coding RNAs (ncRNAs) do not generally code for proteins, but can modulate biological processes at the post-transcriptional level through a variety of molecular mechanisms. An increased number of ncRNA expression profiles have been found in PAs. Therefore, understanding the expression patterns of different ncRNAs could be a promising method for developing non-invasive biomarkers. This review summarizes the expression patterns of dysregulated ncRNAs (microRNAs, long non-coding RNAs, and circular RNAs) involved in PA, which could one day serve as innovative biomarkers or therapeutic targets for the treatment of this neoplasia. We also discuss the potential molecular pathways by which the dysregulated ncRNAs could cause PA and affect its progression.

Emerging Roles of miRNA, lncRNA, circRNA, and Their Cross-Talk in Pituitary Adenoma

Pituitary adenoma (PA) is a common intracranial tumor without specific biomarkers for diagnosis and treatment. Non-coding RNAs (ncRNAs), including microRNAs (miRNA), long non-coding RNA (lncRNA), and circular RNA (circRNA), regulate a variety of cellular processes, such as cell proliferation, differentiation, and apoptosis. Increasing studies have shown that the dysregulation of ncRNAs, especially the cross-talk between lncRNA/circRNA and miRNA, is related to the pathogenesis, diagnosis, and prognosis of PA. Therefore, ncRNAs can be considered as promising biomarkers for PA. In this review, we summarize the roles of ncRNAs from different specimens (i.e., tissues, biofluids, cells, and exosomes) in multiple subtypes of PA and highlight important advances in understanding the contribution of the cross-talk between ncRNAs (e.g., competing endogenous RNAs) to PA disease.

Long non-coding RNA-small nucleolar RNA host gene 7 regulates inflammatory responses following spinal cord injury by regulating the microRNA-449a/TNF-α-induced protein 3-interacting protein 2 axis

The current study aimed to explore the anti-inflammatory effects of long non-coding RNA-small nucleolar RNA host gene 7 (lncRNA-SNHG7) and its mechanism in spinal cord injury (SCI) models. SCI models were established both in vivo and in vitro. Reverse transcription-quantitative PCR was performed to determine the expression levels of lncRNA-SNHG7 in SCI models. Bioinformatics analysis and dual-luciferase reporter assays were carried out to confirm the interaction between lncRNA-SNHG7 with microRNA (miR)-499a and TNF-α-induced protein 3-interacting protein 2 (TNIP2). In addition, cell viability, apoptosis, and the secretion of inflammatory cytokines were assessed by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide (MTT) assay, flow cytometric analysis, and enzyme linked immunosorbent assay (ELISA), respectively. The results showed that lncRNA-SNHG7 was markedly downregulated in the SCI model group. LncRNA-SNHG7 directly bound to miR-499a, which in turn directly targeted TNIP2. In addition, TNIP2 was significantly decreased in SCI rats and lipopolysaccharide (LPS)-treated PC-12 cells. The in vitro results in PC-12 cells revealed that lncRNA-SNHG7 overexpression attenuated neuronal cell death and SCI-mediated inflammatory responses by regulating miR-449a expression. Furthermore, miR-499a knockdown inhibited LPS-induced PC-12 cell injury by targeting TNIP2. In conclusion, lncRNA-SNHG7 modulates the apoptosis and inflammation of PC-12 cells by regulating the miR-449a/TNIP2/NF-κB signaling pathway.

lncRNA SNHG26 promoted the growth, metastasis, and cisplatin resistance of tongue squamous cell carcinoma through PGK1/Akt/mTOR signal pathway

Tongue squamous cell carcinoma (TSCC) is closely linked to head and neck cancers. Here, we sought to explore the role and mechanism of lncRNAs in the occurrence and progression of TSCC and cisplatin resistance. The results of next-generation transcriptomic sequencing revealed that lncRNA-SNHG26 was differentially expressed and was associated with TSCC cisplatin resistance. The Cancer Genome Atlas dataset and tumor tissue analysis revealed that high SHNG26 expression was associated with the occurrence, progression, and poor prognosis of TSCC. Evidence from cell and animal experiments showed that SNHG26 expression was positively correlated with TSCC proliferation, epithelial-mesenchymal transformation, migration, invasion, and cisplatin resistance. Furthermore, in TSCC cells, SNHG26 was found to bind directly to the PGK1 protein, inhibiting its ubiquitination and activating the Akt/mTOR signaling pathway. These findings suggest that lncRNA-SNHG26 may be a promising target for inhibiting TSCC progression and improving sensitivity to cisplatin chemotherapy in TSCC.

Silencing of long chain noncoding RNA paternally expressed gene (PEG10) inhibits the progression of neuroblastoma by regulating microRNA-449a (miR-449a)/ribosomal protein S2 (RPS2) axis

To investigate the mechanism of paternally expressed gene (PEG10) in regulating neuroblastoma (NB) progression. PEG10 expression was detected using quantitative real-time reverse transcription polymerase-chain reaction (qRT-PCR). The interaction of miR-449a and PEG10 or ribosomal protein S2 (RPS2) was employed by starBase, and then proved through RIP and dual-luciferase reporter assays. The NB cell viability, proliferation, invasion, and migration were evaluated by Cell Counting Kit-8 (CCK-8), colony formation, and Transwell assay. The mRNA and protein levels were determined by qRT-PCR and Western blotting, respectively. The levels of PEG10 and RPS2 were remarkably increased in NB tissues and cells, nevertheless the expression of miR-449a was conspicuously declined in NB tissues and cells. Silencing of PEG10 inhibited proliferation, migration, and invasion in SK-N-BE (2) cells, while overexpression of PEG10 promoted proliferation, migration, and invasion in SH-SY5Y cells. We affirmed that PEG10 interacted with miR-449a, and miR-449a could target the 3'UTR of RPS2 and negatively regulate its expression in NB cells. The upregulation of miR-449a inhibited proliferation, migration, and invasion in SK-N-BE (2) cells, while downregulation of miR-449a promoted proliferation, migration, and invasion in SH-SY5Y cells. Moreover, miR-449a overexpression weaken the function of PEG10-mediated on promoting proliferation, migration, and invasion in SH-SY5Y cells, while RPS2 overexpression rescued the effects of miR-449a-mediated on inhibiting those behaviors of SH-SY5Y cells. In conclusion, Silencing of PEG10 could inhibit proliferation, migration, and invasion via the miR-449a/RPS2 axis in NB cells.

Oncogenic Roles of Small Nucleolar RNA Host Gene 7 (SNHG7) Long Noncoding RNA in Human Cancers and Potentials

Long noncoding RNAs (lncRNAs) are a class of noncoding transcripts characterized with more than 200 nucleotides of length. Unlike their names, some short open reading frames are recognized for them encoding small proteins. LncRNAs are found to play regulatory roles in essential cellular processes such as cell growth and apoptosis. Therefore, an increasing number of lncRNAs are identified with dysregulation in a wide variety of human cancers. SNHG7 is an lncRNA with upregulation in cancer cells and tissues. It is frequently reported with potency of promoting malignant cell behaviors in vitro and in vivo. Like oncogenic/tumor suppressor lncRNAs, SNHG7 is found to exert its tumorigenic functions through interaction with other biological substances. These include sponging target miRNAs (various numbers are identified), regulation of several signaling pathways, transcription factors, and effector proteins. Importantly, clinical studies demonstrate association between high SNHG7 expression and clinicopathological features in cancerous patients, worse prognosis, and enhanced chemoresistance. In this review, we summarize recent studies in three eras of cell, animal, and human experiments to bold the prognostic, diagnostic, and therapeutic potentials.

The Emerging Role of Non-Coding RNAs in Pituitary Gland Tumors and Meningioma

Long non-coding RNAs (lncRNAs), microRNAs (miRNAs), and circular RNAs (circRNAs) are non-coding transcripts which are involved in the pathogenesis of pituitary gland tumors. LncRNAs that participate in the pathogenesis of pituitary gland tumors mainly serve as sponges for miRNAs. CLRN1-AS1/miR-217, XIST/miR-424-5p, H19/miR-93a, LINC00473/miR-502-3p, SNHG7/miR-449a, MEG8/miR-454-3p, MEG3/miR-23b-3p, MEG3/miR-376B-3P, SNHG6/miR-944, PCAT6/miR-139-3p, lncRNA-m433s1/miR-433, TUG1/miR-187-3p, SNHG1/miR-187-3p, SNHG1/miR-302, SNHG1/miR-372, SNHG1/miR-373, and SNHG1/miR-520 are identified lncRNA/miRNA pairs that are involved in this process. Hsa_circ_0001368 and circOMA1 are two examples of circRNAs that contribute to the pathogenesis of pituitary gland tumors. Meanwhile, SNHG1, LINC00702, LINC00460, and MEG3 have been found to partake in the pathogenesis of meningioma. In the current review, we describe the role of non-coding RNAs in two types of brain tumors, i.e., pituitary tumors and meningioma.

Small nucleolar RNA host gene 8: A rising star in the targets for cancer therapy

Long non-coding RNAs (lncRNAs) are a group of transcripts that have been considered essential participants in cancer pathogenesis and progression over the past few decades. Small nucleolar RNA host gene 8 (SNHG8) is a newly discovered lncRNA that belongs to the SNHG family, a group of transcripts that can be processed into small nucleolar RNAs and exert important biological functions. As an oncogenic factor, SNHG8 is upregulated in multiple cancer types. Herein, we summarize the biological role of SNHG8 in different cancer types and the underlying mechanisms related to the interaction between SNHG8 and microRNAs, mRNAs, and proteins. In addition, this study emphasizes the clinical value of SNHG8 in cancer, hoping to provide new insights into cancer diagnosis, prognosis, and treatment.

lncRNA MEG3 inhibits pituitary tumor development by participating in cell proliferation, apoptosis and EMT processes

Pituitary tumors do not pose a threat to life but can cause visual disturbances and serious clinical syndromes, such as infertility and metabolic syndrome. Therefore, screening of key genes involved in the occurrence and development of pituitary tumors can provide new targets for the treatment of pituitary tumors. The aim of the present study was to investigate the molecular mechanism of long non‑coding (lnc.) RNA maternally expressed 3 (MEG3) in cell proliferation, apoptosis and epithelial‑mesenchymal transition (EMT) processes of pituitary tumor. Tissue samples were obtained from 34 patients who underwent surgical treatment of pituitary tumors. Pituitary tumor cells (GH3 and MMQ) were transfected with pcDNA3.1(+)‑MEG3, short hairpin (sh)MEG3, microRNA (miR)‑23‑3p inhibitor or their controls using Lipofectamine^® 2000. Reverse transcription‑quantitative PCR and western blot analyses were used to detect the levels of MEG3, miR‑23b‑3p and FOXO4, as well as proliferation‑, apoptosis‑ and EMT‑associated genes and proteins. Cell Counting Kit‑8 and flow cytometry assays were performed to detect proliferation and apoptosis, and Transwell assay was undertaken to assess invasion and migration. Luciferase reporter and RNA pulldown assays were performed to verify the binding between lncRNA MEG3, miR‑23b‑3p and FOXO4. Pearson's correlation analysis was used to analyze the correlation between expression levels of MEG3, miR‑23b‑3p and FOXO4. lncRNA MEG3 was expressed at lower levels in pituitary tumor tissues and cells. Overexpression of lncRNA MEG3 inhibited proliferation, invasion and migration and accelerated apoptosis of pituitary tumor cells. lncRNA MEG3 negatively regulated miR‑23b‑3p expression levels, while miR‑23b‑3p negatively regulated FOXO4 expression levels. Overexpression of lncRNA MEG3 inhibited the EMT process in pituitary tumor cells. miR‑23‑3p inhibitor rescued the effect of shMEG3 on proliferation, invasion, migration, apoptosis and the EMT process in pituitary tumor cells. lncRNA MEG3 inhibited pituitary tumor development by participating in cell proliferation, apoptosis and the EMT process, which may present a novel target for pituitary tumor treatment.