STX12 lncRNA/miR-148a/SMAD5 participate in the regulation of pancreatic stellate cell activation through a mechanism involving competing endogenous RNA

Long non-coding RNAs and pancreatic cancer: A multifaceted view

Pancreatic cancer (PC) is a highly malignant disease with a 5-year survival rate of only 10%. Families with PC are at greater risk, as are type 2 diabetes, pancreatitis, and other factors. Insufficient early detection methods make this cancer have a poor prognosis. Additionally, the molecular mechanisms underlying PC development remain unclear. Increasing evidence suggests that long non-coding RNAs (lncRNAs) contribute to PC pathology,which may control gene expression by recruiting histone modification complexes to chromatin and interacting with proteins and RNAs. In recent studies, abnormal regulation of lncRNAs has been implicated in PC proliferation, metastasis, invasion, angiogenesis, apoptosis, and chemotherapy resistance suggesting potential clinical implications. The paper reviews the progress of lncRNA research in PC about diabetes mellitus, pancreatitis, cancer metastasis, tumor microenvironment regulation, and chemoresistance. Furthermore, lncRNAs may serve as potential therapeutic targets and biomarkers for PC diagnosis and prognosis. This will help improve PC patients' survival rate from a lncRNA perspective.

Pancreatic stellate cells - rising stars in pancreatic pathologies

Pluripotent pancreatic stellate cells (PSCs) receive growing interest in past decades. Two types of PSCs are recognized –vitamin A accumulating quiescent PSCs and activated PSCs- the main producents of extracellular matrix in pancreatic tissue. PSCs plays important role in pathogenesis of pancreatic fibrosis in pancreatic cancer and chronic pancreatitis. PSCs are intensively studied as potential therapeutical target because of their important role in developing desmoplastic stroma in pancreatic cancer. There also exists evidence that PSC are involved in other pathologies like type-2 diabetes mellitus. This article brings brief characteristics of PSCs and recent advances in research of these cells.

TGF-β1 induced proliferation, migration, and ECM accumulation through the SNHG11/miR-34b/LIF pathway in human pancreatic stellate cells

Chronic pancreatitis (CP) is a chronic inflammatory and fibrotic disease of the pancreas, and activated pancreatic stellate cells (PSCs) play a vital role in the progression of pancreatic fibrosis in CP. It has been reported that long non-coding RNA small nucleolar RNA host gene 11 (SNHG11) is highly expressed in chronic pancreatitis (CP) patients. However, the role of SNHG11 in CP progression is unclear. The purport of the study was to survey the role of SNHG11 in CP. We employed transforming growth factor (TGF)-beta1 (TGF-β1) to activate human pancreatic stellate cells (PSCs). Expression of SNHG11 was assessed with qRT-PCR. Loss-of-function experiments were executed to evaluate the effects of SNHG11 on the proliferation and migration of TGF-β1-treated PSCs. Some protein levels were detected by western blotting. The regulatory mechanism of SNHG11 was verified by the dual-luciferase reporter and RIP assays. As a result, SNHG11 was upregulated in plasma of CP patients and TGF-β1-treated PSCs. Also, SNHG11 inhibition reduced TGF-β1-induced proliferation, migration, and ECM accumulation in PSCs. Mechanistically, SNHG11 regulated leukemia inhibitory factor (LIF) expression by sponging miR-34b. Furthermore, miR-34b inhibitor abolished SNHG11 silencing-mediated effects on TGF-β1-treated PSC proliferation, migration, and ECM accumulation. LIF overexpression counteracted the repressive influence of miR-34b mimic on proliferation, migration, and ECM accumulation of TGF-β1-treated PSCs. In conclusion, SNHG11 knockdown reduced TGF-β1-induced PSC proliferation, migration, and ECM accumulation by the miR-34b/LIF axis.

Lnc-PFAR facilitates autophagy and exacerbates pancreatic fibrosis by reducing pre-miR-141 maturation in chronic pancreatitis

Chronic pancreatitis (CP) is described as progressive inflammatory fibrosis of pancreas, accompanied with irreversible impaired endocrine and exocrine insufficiency. Pancreatic stellate cells (PSCs) are widely distributed in the stroma of the pancreas and PSCs activation has been shown as one of the leading causes for pancreatic fibrosis. Our previous study has revealed that autophagy is dramatically activated in CP tissues, which facilitates PSCs activation and pancreatic fibrosis. Long non-coding RNAs (LncRNAs) have been recognized as crucial regulators for fibrosis-related diseases. LncRNAs interact with RNA binding protein or construct competitive endogenous RNA (ceRNA) hypothesis which elicited the fibrotic processes. Until now, the effects of lncRNAs on PSCs activation and pancreatic fibrosis have not been clearly explored. In this study, a novel lncRNA named Lnc-PFAR was found highly expressed in mouse and human CP tissues. Our data revealed that Lnc-PFAR facilitates PSCs activation and pancreatic fibrosis via RB1CC1-induced autophagy. Lnc-PFAR reduces miR-141 expression by suppressing pre-miR-141 maturation, which eventually upregulates the RB1CC1 and fibrosis-related indicators expression. Meanwhile, Lnc-PFAR enhanced PSCs activation and pancreatic fibrosis through trigging autophagy. Our study interrogates a novel lncRNA-induced mechanism in promoting the development of pancreatic fibrosis, and Lnc-PFAR is suggested to be a prospective therapeutic target in clinical scenarios.

Molecular Mechanism of Pancreatic Stellate Cells Activation in Chronic Pancreatitis and Pancreatic Cancer

Activated pancreatic stellate cells (PSCs) are the main effector cells in the process of fibrosis, a major pathological feature in pancreatic diseases that including chronic pancreatitis and pancreatic cancer. During tumorigenesis, quiescent PSCs change into an active myofibroblast-like phenotype which could create a favorable tumor microenvironment and facilitate cancer progression by increasing proliferation, invasiveness and inducing treatment resistance of pancreatic cancer cells. Many cellular signals are revealed contributing to the activation of PSCs, such as transforming growth factor-β, platelet derived growth factor, mitogen-activated protein kinase (MAPK), Smads, nuclear factor-κB (NF-κB) pathways and so on. Therefore, investigating the role of these factors and signaling pathways in PSCs activation will promote the development of PSCs-specific therapeutic strategies that may provide novel options for pancreatic cancer therapy. In this review, we systematically summarize the current knowledge about PSCs activation-associated stimulating factors and signaling pathways and hope to provide new strategies for the treatment of pancreatic diseases.

Long noncoding RNA SMAD5-AS1 acts as a microRNA-106a-5p sponge to promote epithelial mesenchymal transition in nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a malignant epithelial cancer of the head and neck with high prevalence in southern China, which is accompanied by notable invasiveness and metastasis. Long noncoding RNAs (lncRNAs) participate in the progression of various cancers including NPC. Microarray-based analysis identified highly expressed lncRNA mothers against decapentaplegic homolog 5 (SMAD5)-antisense RNA 1 (AS1) related to NPC. Interestingly, it is found that SMAD5-AS1 competitively bound to microRNA (miR)-106a-5p to regulate SMAD5. Herein, the study aimed to clarify the role of SMAD5-AS1/miR-106a-5p/SMAD5 axis in the process of epithelial mesenchymal transition (EMT) in NPC. SMAD5-AS1 was highly expressed and miR-106a-5p was poorly expressed in NPC tissues and cell lines. The NPC cells were treated with a series of small interfering RNAs, mimics, or inhibitors to explore the effects of SMAD5-AS1, SMAD5, and miR-106a-5p on EMT, cell proliferation, migration, and invasion in NPC. Of note, SMAD5-AS1 silencing or miR-106a-5p overexpression reduced expression of N-cadherin, matrix metallopeptidase 9, Snail, and Vimentin while elevating E-cadherin expression, thus inhibiting EMT, cell proliferation, migration, and invasion in NPC by down-regulation of SMAD5. Moreover, SMAD5 silencing could reduce the ability of EMT induced by SMAD5-AS1 up-regulation. SMAD5-AS1 silencing or miR-106a-5p elevation inhibited tumorigenesis in nude mice. Taken together, SMAD5-AS1 silencing suppressed EMT, cell proliferation, migration, and invasion in NPC by elevating miR-106a-5p to down-regulate SMAD5, which provided a novel therapeutic target for NPC treatment.-Zheng, Y.-J., Zhao, J.-Y., Liang, T.-S., Wang, P., Wang, J., Yang, D.-K., Liu, Z.-S. Long noncoding RNA SMAD5-AS1 acts as a microRNA-106a-5p sponge to promote epithelial mesenchymal transition in nasopharyngeal carcinoma.

Epigenetic Mechanisms of Pancreatobiliary Fibrosis

PURPOSE OF REVIEW

The goal of this manuscript is to review the current literature related to fibrogenesis in the pancreatobiliary system and how this process contributes to pancreatic and biliary diseases. In particular, we seek to define the current state of knowledge regarding the epigenetic mechanisms that govern and regulate tissue fibrosis in these organs. A better understanding of these underlying molecular events will set the stage for future epigenetic therapeutics.

RECENT FINDINGS

We highlight the significant advances that have been made in defining the pathogenesis of pancreatobiliary fibrosis as it relates to chronic pancreatitis, pancreatic cancer, and the fibro-obliterative cholangiopathies. We also review the cell types involved as well as concepts related to epithelial-mesenchymal crosstalk. Furthermore, we outline important signaling pathways (e.g., TGFβ) and diverse epigenetic processes (i.e., DNA methylation, non-coding RNAs, histone modifications, and 3D chromatin remodeling) that regulate fibrogenic gene networks in these conditions. We review a growing body of scientific evidence linking epigenetic regulatory events to fibrotic disease states in the pancreas and biliary system. Advances in this understudied area will be critical toward developing epigenetic pharmacological approaches that may lead to more effective treatments for these devastating and difficult to treat disorders.

LncRNA: Shedding light on mechanisms and opportunities in fibrosis and aging

Fibrosis is universally observed in multiple aging-related diseases and progressions and is characterized by excess accumulation of the extracellular matrix. Fibrosis occurs in various human organs and eventually results in organ failure. Noncoding RNAs (ncRNAs) have emerged as essential regulators of cellular signaling and relevant human diseases. In particular, the enigmatic class of long noncoding RNAs (lncRNAs) is a kind of noncoding RNA that is longer than 200 nucleotides and does not possess protein coding ability. LncRNAs have been identified to exert both promotive and inhibitory effects on the multifaceted processes of fibrosis. A growing body of studies has revealed that lncRNAs are involved in fibrosis in various organs, including the liver, heart, lung, and kidney. As lncRNAs have been increasingly identified, they have become promising targets for anti-fibrosis therapies. This review systematically highlights the recent advances regarding the roles of lncRNAs in fibrosis and sheds light on the use of lncRNAs as a potential treatment for fibrosis.

Long noncoding RNA myocardial infarction-associated transcript regulated the pancreatic stellate cell activation to promote the fibrosis process of chronic pancreatitis

BACKGROUND

Long noncoding RNAs (lncRNAs) play crucial roles in fibrosis process. In our previous RNA-seq study, we found that lncRNA myocardial infarction-associated transcript (MIAT) was differentially expressed in pancreatic tissues of chronic pancreatitis (CP) patients. However, the function of MIAT in CP remains unknown. This study was aimed to investigate the function and underlying mechanism of MIAT in pancreatic fibrosis.

MATERIALS AND METHODS

The expression levels of MIAT, miR-216a-3p, cyclooxygenase 2 (COX-2), α-smooth muscle actin (α-SMA), and collagen I were estimated by Western blot analysis and qualitative reverse transcription polymerase chain reaction. The relationships between miR-216a-3p, MIAT, and COX-2 were confirmed by luciferase reporter assay. The proliferation of human pancreatic stellate cells (HPaSteCs) was detected by cell counting kit-8 assay.

RESULTS

We found that MIAT, along with the levels of fibrosis-related proteins α-SMA and collagen I, as well as COX-2 were upregulated, while miR-216a-3p was downregulated in transforming growth factor (TGF)-β1-stimulated HPaSteCs. Mechanistically, MIAT acted as a molecular sponge for miR-216a-3p. Furthermore, we identified COX-2 as a direct target of miR-126a-3p. Additionally, MIAT overturned the inhibitory effect of miR-216a-3p overexpression and COX-2 knockdown on the activation and proliferation of HPaSteCs.

CONCLUSION

Our study provided mechanistic insights into a critical role for MIAT as a miRNA sponge in CP.

linc-SCRG1 accelerates liver fibrosis by decreasing RNA-binding protein tristetraprolin

The biologic roles of long noncoding RNAs (lncRNAs) in liver fibrosis remained unknown. Through microarray analysis, linc-SCRG1 (a lncRNA with transcript length 3118 bp) was found up-regulated 13.62-fold in human cirrhotic tissues. Quantitative PCR verified that linc-SCRG1 increased along with liver fibrosis progression in human tissues and in activated LX2 cells induced by TGF-β1. Knockdown of linc-SCRG1 significantly reversed the effects of TGF-β1 on LX2, including inhibiting activation, promoting apoptosis, reducing proliferation, lessening invasion, and down-regulating genes [fibrosis-related mRNA: α-smooth muscle actin ( α-SMA), type I collagen, and B-cell lymphoma-2; invasion-related mRNA: matrix metallopeptidase-2 ( MMP-2), MMP-9, and MMP-13; inflammation-related mRNA: TNF-α, IL-6, and IL-10]. linc-SCRG1 had binding sites with tristetraprolin (TTP), a kind of RNA-binding protein, and specifically combined to TTP proteins. Overexpression of linc-SCRG1 would cause TTP mRNA unstably and proteins decreasing. TTP mRNA was proved having negative relevance with linc-SCRG1 and was gradually reduced during human liver fibrosis progression. Overexpressing TTP resulted in knockdown of lincSCRG1 and degraded downstream target genes ( MMP-2 and TNF-α) in activated LX2. Overexpressing TTP had the same effects as small interfering RNA-lincSCRG1 (si- lincSCRG1), whereas knockdown of TTP had reversal effects on si- lincSCRG1 in activated LX2. In summary, linc-SCRG1 reduced TTP and restricted its degradation of target genes TNF-α and MMP-2. Therefore, linc-SCRG1 had a repressing TTP-elicited inactivation effect on hepatic stellate cell (HSC) phenotypes. Inhibition of linc-SCRG1 may be a novel therapeutic approach to inactivate HSCs and extenuate human liver fibrosis.-Wu, J.-C., Luo, S.-Z., Liu, T., Lu, L.-G., Xu, M.-Y. linc-SCRG1 accelerates liver fibrosis by decreasing RNA-binding protein tristetraprolin.

Screening and validation of differentially expressed extracellular miRNAs in acute pancreatitis

The present study aimed to screen for differentially expressed extracellular microRNAs (miRNAs) during the development of acute pancreatitis (AP) and validate the miRNA expression in the plasma of patients with AP. The culture medium of taurolithocholic acid‑3 sulfate‑treated rat pancreatic acinar AR42J cells was collected to extract total RNA for miRNA microarray analysis. Compared with the miRNA test results of the AP rats in the GEO databases, the differentially expressed extracellular miRNAs were screened. The TargetScan, miRanda, and PicTar programs were used for target gene prediction of the identified miRNAs, and gene ontology‑biological processes (GO‑BP) functional annotation was performed. Finally, the results from the combined microarray analyses (in vitro cell line and in vivo rat samples) were validated using plasma samples from patients with mild and moderately severe AP by reverse transcription‑polymerase chain reaction. The results demonstrated that extracellular miR‑24 was differentially expressed by microarray and bioinformatics analysis in both the cell line and the animal model of AP. Bioinformatics prediction analysis revealed that downstream target genes of miR‑24 included Vav2, Syk, Lhcgr, Slc9a3r1, Cacnb1, Cacna1b, Bcl10, and Fgd3. Functional enrichment analysis revealed that the main GO‑BP predicted functional presentations were positive regulation of calcium‑mediated signaling, activation of c‑Jun N‑terminal kinase activity, calcium ion transport, regulation of Rho protein signal transduction, negative regulation of the protein kinase B signaling cascade, and the T cell receptor signaling pathway. Validation analysis for the plasma miR‑24 expression in humans revealed a significant upregulation of miR‑24 in the plasma samples of AP patients compared with the healthy controls, while no significant difference was observed in the miR‑24 expression between the mild and the moderately severe AP groups. The present study confirmed the high expression of miR‑24 in peripheral blood during AP, suggesting that miR‑24 might have an intercellular communication role contributing to the AP‑associated distant organ injury.