miR-34a inhibits pancreatic cancer progression through Snail1-mediated epithelial-mesenchymal transition and the Notch signaling pathway

Exploiting Matrix Stiffness to Overcome Drug Resistance

Drug resistance is arguably one of the biggest challenges facing cancer research today. Understanding the underlying mechanisms of drug resistance in tumor progression and metastasis are essential in developing better treatment modalities. Given the matrix stiffness affecting the mechanotransduction capabilities of cancer cells, characterization of the related signal transduction pathways can provide a better understanding for developing novel therapeutic strategies. In this review, we aimed to summarize the recent advancements in tumor matrix biology in parallel to therapeutic approaches targeting matrix stiffness and its consequences in cellular processes in tumor progression and metastasis. The cellular processes governed by signal transduction pathways and their aberrant activation may result in activating the epithelial-to-mesenchymal transition, cancer stemness, and autophagy, which can be attributed to drug resistance. Developing therapeutic strategies to target these cellular processes in cancer biology will offer novel therapeutic approaches to tailor better personalized treatment modalities for clinical studies.

Using microRNAs Networks to Understand Pancreatic Cancer-A Literature Review

Pancreatic cancer is a severe disease, challenging to diagnose and treat, and thereby characterized by a poor prognosis and a high mortality rate. Pancreatic ductal adenocarcinoma (PDAC) represents approximately 90% of pancreatic cancer cases, while other cases include neuroendocrine carcinoma. Despite the growing knowledge of the pathophysiology of this cancer, the mortality rate caused by it has not been effectively reduced. Recently, microRNAs have aroused great interest among scientists and clinicians, as they are negative regulators of gene expression, which participate in many processes, including those related to the development of pancreatic cancer. The aim of this review is to show how microRNAs (miRNAs) affect key signaling pathways and related cellular processes in pancreatic cancer development, progression, diagnosis and treatment. We included the results of in vitro studies, animal model of pancreatic cancer and those performed on blood, saliva and tumor tissue isolated from patients suffering from PDAC. Our investigation identified numerous dysregulated miRNAs involved in KRAS, JAK/STAT, PI3/AKT, Wnt/β-catenin and TGF-β signaling pathways participating in cell cycle control, proliferation, differentiation, apoptosis and metastasis. Moreover, some miRNAs (miRNA-23a, miRNA-24, miRNA-29c, miRNA-216a) seem to be engaged in a crosstalk between signaling pathways. Evidence concerning the utility of microRNAs in the diagnosis and therapy of this cancer is poor. Therefore, despite growing knowledge of the involvement of miRNAs in several processes associated with pancreatic cancer, we are beginning to recognize and understand their role and usefulness in clinical practice.

MicroRNAs as the critical regulators of epithelial mesenchymal transition in pancreatic tumor cells

Pancreatic cancer (PC), as one of the main endocrine and digestive systems malignancies has the highest cancer related mortality in the world. Lack of the evident clinical symptoms and appropriate diagnostic markers in the early stages of tumor progression are the main reasons of the high mortality rate among PC patients. Therefore, it is necessary to investigate the molecular pathways involved in the PC progression, in order to introduce novel early diagnostic methods. Epithelial mesenchymal transition (EMT) is a critical cellular process associated with pancreatic tumor cells invasion and distant metastasis. MicroRNAs (miRNAs) are also important regulators of EMT process. In the present review, we discussed the role of miRNAs in regulation of EMT process during PC progression. It has been reported that the miRNAs mainly regulate the EMT process in pancreatic tumor cells through the regulation of EMT-specific transcription factors and several signaling pathways such as WNT, NOTCH, TGF-β, JAK/STAT, and PI3K/AKT. Considering the high stability of miRNAs in body fluids and their role in regulation of EMT process, they can be introduced as the non-invasive diagnostic markers in the early stages of malignant pancreatic tumors. This review paves the way to introduce a non-invasive EMT based panel marker for the early tumor detection among PC patients.

MicroRNA-34 and gastrointestinal cancers: a player with big functions

It is commonly assumed that gastrointestinal cancer is the most common form of cancer across the globe and is the leading contributor to cancer-related death. The intricate mechanisms underlying the growth of GI cancers have been identified. It is worth mentioning that both non-coding RNAs (ncRNAs) and certain types of RNA, such as circular RNAs (circRNAs), long non-coding RNAs (lncRNAs), and microRNAs (miRNAs), can have considerable impact on the development of gastrointestinal (GI) cancers. As a tumour suppressor, in the group of short non-coding regulatory RNAs is miR-34a. miR-34a silences multiple proto-oncogenes at the post-transcriptional stage by targeting them, which inhibits all physiologically relevant cell proliferation pathways. However, it has been discovered that deregulation of miR-34a plays important roles in the growth of tumors and the development of cancer, including invasion, metastasis, and the tumor-associated epithelial-mesenchymal transition (EMT). Further understanding of miR-34a's molecular pathways in cancer is also necessary for the development of precise diagnoses and effective treatments. We outlined the most recent research on miR-34a functions in GI cancers in this review. Additionally, we emphasize the significance of exosomal miR-34 in gastrointestinal cancers.

MicroRNAs in Pancreatic Cancer: Advances in Biomarker Discovery and Therapeutic Implications

Pancreatic cancer remains a formidable malignancy characterized by high mortality rates, primarily attributable to late-stage diagnosis and a dearth of effective therapeutic interventions. The identification of reliable biomarkers holds paramount importance in enhancing early detection, prognostic evaluation, and targeted treatment modalities. Small non-coding RNAs, particularly microRNAs, have emerged as promising candidates for pancreatic cancer biomarkers in recent years. In this review, we delve into the evolving role of cellular and circulating miRNAs, including exosomal miRNAs, in the diagnosis, prognosis, and therapeutic targeting of pancreatic cancer. Drawing upon the latest research advancements in omics data-driven biomarker discovery, we also perform a case study using public datasets and address commonly identified research discrepancies, challenges, and limitations. Lastly, we discuss analytical approaches that integrate multimodal analyses incorporating clinical and molecular features, presenting new insights into identifying robust miRNA-centric biomarkers.

The roles of lncRNAs and miRNAs in pancreatic cancer: a focus on cancer development and progression and their roles as potential biomarkers

Pancreatic ductal adenocarcinoma (PDAC) is among the most penetrative malignancies affecting humans, with mounting incidence prevalence worldwide. This cancer is usually not diagnosed in the early stages. There is also no effective therapy against PDAC, and most patients have chemo-resistance. The combination of these factors causes PDAC to have a poor prognosis, and often patients do not live longer than six months. Because of the failure of conventional therapies, the identification of key biomarkers is crucial in the early diagnosis, treatment, and prognosis of pancreatic cancer. 65% of the human genome encodes ncRNAs. There are different types of ncRNAs that are classified based on their sequence lengths and functions. They play a vital role in replication, transcription, translation, and epigenetic regulation. They also participate in some cellular processes, such as proliferation, differentiation, metabolism, and apoptosis. The roles of ncRNAs as tumor suppressors or oncogenes in the growth of tumors in a variety of tissues, including the pancreas, have been demonstrated in several studies. This study discusses the key roles of some lncRNAs and miRNAs in the growth and advancement of pancreatic carcinoma. Because they are involved not only in the premature identification, chemo-resistance and prognostication, also their roles as potential biomarkers for better management of PDAC patients.

Functional and Potential Therapeutic Implication of MicroRNAs in Pancreatic Cancer

The alarmingly low five-year survival rate for pancreatic cancer presents a global health challenge, contributing to about 7% of all cancer-related deaths. Late-stage diagnosis and high heterogeneity are the biggest hurdles in treating pancreatic cancer. Thus, there is a pressing need to discover novel biomarkers that could help in early detection as well as improve therapeutic strategies. MicroRNAs (miRNAs), a class of short non-coding RNA, have emerged as promising candidates with regard to both diagnostics and therapeutics. Dysregulated miRNAs play pivotal roles in accelerating tumor growth and metastasis, orchestrating tumor microenvironment, and conferring chemoresistance in pancreatic cancer. The differential expression profiles of miRNAs in pancreatic cancer could be utilized to explore novel therapeutic strategies. In this review, we also covered studies on recent advancements in various miRNA-based therapeutics such as restoring miRNAs with a tumor-suppressive function, suppressing miRNA with an oncogenic function, and combination with chemotherapeutic drugs. Despite several challenges in terms of specificity and targeted delivery, miRNA-based therapies hold the potential to revolutionize the treatment of pancreatic cancer by simultaneously targeting multiple signaling pathways.

Differential miRNA expression of hypoxic MCF7 and PANC-1 cells

Background

Hypoxia plays a critical role in the tumor microenvironment by affecting cellular proliferation, metabolism, apoptosis, DNA repair, and chemoresistance. Since hypoxia provokes a distinct shift of microRNA, it is important to illustrate the relative contribution of each hypoxamiR to cancer progression.

Aims

The present study aims to shed light on the hypoxamiRs that are involved in pancreatic and breast cancer progression to highlight novel targets for the development of new therapies.

Methods

For 20 cycles, MCF7 breast cancer cells and PANC-1 pancreatic cancer cells were subjected to chronic cyclic hypoxia, which consisted of 72 hours of hypoxia followed by 24 hours of reoxygenation. After 10 and 20 cycles of hypoxia, miRNA expression alterations were profiled using RT-PCR array and further analyzed using a visual analytics platform. The MTT cell proliferation assay was used to determine hypoxic cells' chemoresistance to doxorubicin.

Results

Under chronic cyclic hypoxia, hypoxic PANC-1 cells have a comparable doubling time with their normoxic counterparts, whereas hypoxic MCF7 cells show a massive increase in doubling time when compared to their normoxic counterparts. Both hypoxic cell lines developed EMT-like phenotypes as well as doxorubicin resistance. According to the findings of miRNet, 6 and 10 miRNAs were shown to play an important role in enriching six hallmarks of pancreatic cancer in the 10th and 20th cycles of hypoxia, respectively, while 7 and 11 miRNAs were shown to play an important role in enriching the four hallmarks of breast cancer in the 10th and 20th cycles of hypoxia, respectively.

Conclusions

miR-221, miR-21, miR-155, and miR-34 were found to be involved in the potentiation of hypoxic PANC-1 hallmarks at both the 10th and 20th cycles, while miR-93, miR-20a, miR-15, and miR-17 were found to be involved in the potentiation of hypoxic MCF7 hallmarks at both the 10th and 20th cycles. This variation in miRNA expression was also connected to the emergence of an EMT-like phenotype, alterations in proliferation rates, and doxorubicin resistance. The chemosensitivity results revealed that chronic cyclic hypoxia is critical in the formation of chemoresistant phenotypes in pancreatic and breast cancer cells. miR-181a and let-7e expression disparities in PANC1, as well as miR-93, miR-34, and miR-27 expression disparities in MCF7, may be associated with the formation of chemoresistant MCF7 and PANC-1 cells following 20 cycles of chronic cyclic hypoxia. Indeed, further research is needed since the particular mechanisms that govern these processes are unknown.

MiR-146b-5p/SEMA3G regulates epithelial-mesenchymal transition in clear cell renal cell carcinoma

OBJECTIVE

The primary purpose was to unveil how the miR-146b-5p/SEMA3G axis works in clear cell renal cell carcinoma (ccRCC).

METHODS

ccRCC dataset was acquired from TCGA database, and target miRNA to be studied was further analyzed using survival analysis. We performed miRNA target gene prediction through the database, and those predicted miRNAs were intersected with differential mRNAs. After calculating the correlation between miRNAs and mRNAs, we completed the GSEA pathway enrichment analysis on mRNAs. MiRNA and mRNA expression was examined by qRT-PCR. Western blot was introduced to detect SEMA3G, MMP2, MMP9 expression, epithelial-mesenchymal transition (EMT) marker proteins, and Notch/TGF-β signaling pathway-related proteins. Targeted relationship between miRNA and mRNA was validated using a dual-luciferase test. Transwell assay was employed to assess cell migration and invasion. Wound healing assay was adopted for evaluation of migration ability. The effect of different treatments on cell morphology was observed by a microscope.

RESULTS

In ccRCC cells, miR-146b-5p was remarkably overexpressed, yet SEMA3G was markedly less expressed. MiR-146b-5p was capable of stimulating ccRCC cell invasion, migration and EMT, and promoting the transformation of ccRCC cell morphology to mesenchymal state. SEMA3G was targeted and inhibited via miR-146b-5p. MiR-146b-5p facilitated ccRCC cell migration, invasion, morphology transforming to mesenchymal state and EMT process by targeting SEMA3G and regulating Notch and TGF-β signaling pathways.

CONCLUSION

MiR-146b-5p regulated Notch and TGF-β signaling pathway by suppressing SEMA3G expression, thus promoting the growth of ccRCC cells, which provides a possible target for ccRCC therapy and prognosis prediction.

AAV-mediated delivery of osteoblast/osteoclast-regulating miRNAs for osteoporosis therapy

Osteoporosis occurs due to a dysregulation in bone remodeling, a process requiring both bone-forming osteoblasts and bone-resorbing osteoclasts. Current leading osteoporosis therapies suppress osteoclast-mediated bone resorption but show limited therapeutic effects because osteoblast-mediated bone formation decreases concurrently. We developed a gene therapy strategy for osteoporosis that simultaneously promotes bone formation and suppresses bone resorption by targeting two microRNAs (miRNAs)-miR-214-3p and miR-34a-5p. We modulated the expression of these miRNAs using systemically delivered recombinant adeno-associated viral (rAAV) vectors targeting the bone. rAAV-mediated overexpression of miR-214-3p or inhibition of miR-34a-5p in the skeleton resulted in bone loss in adult mice, resembling osteoporotic bones. Conversely, rAAV-mediated inhibition of miR-214-3p or overexpression of miR-34a-5p reversed bone loss in mouse models for postmenopausal and senile osteoporosis by increasing osteoblast-mediated bone formation and decreasing osteoclast-mediated bone resorption. Notably, these mice did not show any apparent pathological phenotypes in non-skeletal tissues. Mechanistically, inhibiting miR-214-3p upregulated activating transcription factor 4 in osteoblasts and phatase and tensin homolog in osteoclasts, while overexpressing miR-34a-5p downregulated Notch1 in osteoblasts and TGF-β-induced factor homeobox 2 in osteoclasts. In summary, bone-targeting rAAV-mediated regulation of miR-214-3p or miR-34a-5p is a promising new approach to treat osteoporosis, while limiting adverse effects in non-skeletal tissues.

The Roles of MicroRNA in Pancreatic Cancer Progression

Pancreatic Ductal Adenocarcinoma (PDAC) has a poor patient survival rate in comparison with other cancer types, even after targeted therapy, chemotherapy, and immunotherapy. Therefore, a great deal needs to be done to gain a better understanding of the biology and identification of prognostic and predictive markers for the development of superior therapies. The microRNAs (miRNAs) belong to small non-coding RNAs that regulate post-transcriptional gene expression. Several shreds of evidence indicate that miRNAs play an important role in the pathogenesis of pancreatic cancer. Here we review the recent developments in miRNAs and their target role in the development, metastasis, migration, and invasion.

Senescence-Associated miRNAs and Their Role in Pancreatic Cancer

Replicative senescence is irreversible cell proliferation arrest for somatic cells which can be circumvented in cancers. Cellular senescence is a process, which may play two opposite roles. On the one hand, this is a natural protection of somatic cells against unlimited proliferation and malignant transformation. On the other hand, cellular secretion caused by senescence can stimulate inflammation and proliferation of adjacent cells that may promote malignancy. The main genes controlling the senescence pathways are also well known as tumor suppressors. Almost 140 genes regulate both cellular senescence and cancer pathways. About two thirds of these genes (64%) are regulated by microRNAs. Senescence-associated miRNAs can stimulate cancer progression or act as tumor suppressors. Here we review the role playing by senescence-associated miRNAs in development, diagnostics and treatment of pancreatic cancer.

Role of microRNAs in response to cadmium chloride in pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most fatal and aggressive malignancies with a 5-year survival rate less than 9%. Early detection is particularly difficult due to the lack of symptoms even in advanced stages. microRNAs (miRs/miRNAs) are small (~ 18-24 nucleotides), endogenous, non-coding RNAs, which are involved in the pathogenesis of several malignancies including PDAC. Alterations of miR expressions can lead to apoptosis, angiogenesis, and metastasis. The role of environmental pollutants such as cadmium (Cd) in PDAC has been suggested but not fully understood. This study underlines the role of miRs (miR-221, miR-155, miR-126) in response to cadmium chloride (CdCl2) in vitro. Lethal concentration (LC50) values for CdCl2 resulted in a toxicity series of AsPC-1 > HPNE > BxPC-3 > Panc-1 = Panc-10.5. Following the treatment with CdCl2, miR-221 and miR-155 were significantly overexpressed, whereas miR-126 was downregulated. An increase in epithelial-mesenchymal transition (EMT) via the dysregulation of mesenchymal markers such as Wnt-11, E-cadherin, Snail, and Zeb1 was also observed. Hence, this study has provided evidence to suggest that the environmental pollutant Cd can have a significant role in the development of PDAC, suggesting a significant correlation between miRs and Cd exposure during PDAC progression. Further studies are needed to investigate the precise role of miRs in PDAC progression as well as the role of Cd and other environmental pollutants.

MicroRNAs as potential therapeutic targets for pancreatic cancer

ABSTRACT

Pancreatic cancer is one of the most aggressive malignancies. The poor prognosis of pancreatic cancer patients is mainly attributed to low diagnostic rate at the early stage, highly aggressive nature coupled with the inadequate efficacy of current chemotherapeutic regimens. Novel therapeutic strategies are urgently needed for pancreatic cancer. MicroRNAs (miRNAs) play an important regulatory role in key processes of cancer development. The aberrant expression of miRNAs is often involved in the initiation, progression, and metastasis of pancreatic cancer. The discovery of tumor suppressor miRNAs provides prospects for the development of a novel treatment strategy for pancreatic cancer. We reviewed recent progress on the understanding of the role of miRNAs in pancreatic cancer, highlighted the efficient application of miRNAs-based therapies for pancreatic cancer in animal models and clinical trials, and proposed future prospects. This review focuses on the promise of integrating miRNAs into the treatment of pancreatic cancer and provides guidance for the development of precision medicine for pancreatic cancer.

Plasma miRNA Biomarkers in Limited Volume Samples for Detection of Early-stage Pancreatic Cancer

Early detection of pancreatic ductal adenocarcinoma (PDAC) is key to improving patient outcomes; however, PDAC is usually diagnosed late. Therefore, blood-based minimally invasive biomarker assays for limited volume clinical samples are urgently needed. A novel miRNA profiling platform (Abcam Fireplex-Oncology Panel) was used to investigate the feasibility of developing early detection miRNA biomarkers with 20 μL plasma from a training set (58 stage II PDAC cases and 30 controls) and two validation sets (34 stage II PDAC cases and 25 controls; 44 stage II PDAC cases and 18 controls). miR-34a-5p [AUC = 0.77; 95% confidence interval (CI), 0.66-0.87], miR-130a-3p (AUC = 0.74; 95% CI, 0.63-0.84), and miR-222-3p (AUC = 0.70; 95% CI, 0.58-0.81) were identified as significantly differentially abundant in plasma from stage II PDAC versus controls. Although none of the miRNAs individually outperformed the currently used serologic biomarker for PDAC, carbohydrate antigen 19-9 (CA19-9), combining the miRNAs with CA 19-9 improved AUCs from 0.89 (95% CI, 0.81-0.95) for CA 19-9 alone to 0.92 (95% CI, 0.86-0.97), 0.94 (95% CI, 0.89-0.98), and 0.92 (95% CI, 0.87-0.97), respectively. Gene set enrichment analyses of transcripts correlated with high and low expression of the three miRNAs in The Cancer Genome Atlas PDAC sample set. These miRNA biomarkers, assayed in limited volume plasma together with CA19-9, discriminate stage II PDAC from controls with good sensitivity and specificity. Unbiased profiling of larger cohorts should help develop an informative early detection biomarker assay for diagnostic settings. PREVENTION RELEVANCE: Development of minimally invasive biomarker assays for detection of premalignant disease and early-stage pancreatic cancer is key to improving patient survival. This study describes a limited volume plasma miRNA biomarker assay that can detect early-stage resectable pancreatic cancer in clinical samples necessary for effective prevention and clinical intervention.

MiR-139 Modulates Cancer Stem Cell Function of Human Breast Cancer through Targeting CXCR4

Elevated expression of C-X-C motif chemokine receptor 4 (CXCR4) correlates with chemotaxis, invasion, and cancer stem cell (CSC) properties within several solid-tumor malignancies. Recent studies reported that microRNA (miRNA) modulates the stemness of embryonic stem cells. We aimed to investigate the role of miRNA, via CXCR4-modulation, on CSC properties in breast cancer using cell lines and xenotransplantation mouse model and evaluated miR-193 levels in 191 patients with invasive ductal carcinoma. We validated miR-139 directly targets the 3'-untranslated region of CXCR4. Hoechst 33342 fluorescence-activated cell sorting (FACS) and sphere-forming assay were used to identify CSCs. MiR-139 suppressed breast CSCs with mesenchymal traits; led to decreased migration and invasion abilities through down-regulating CXCR4/p-Akt signaling. In lung cancer xenograft model of nude mice transplanted with human miR-139-carrying MDA-MB-231 cells, metastatic lung nodules were suppressed. Clinically, microdissected breast tumor tissues showed miR-139 reduction, compared to adjacent non-tumor tissues, that was significantly associated with worse clinicopathological features, including larger tumor size, advanced tumor stage and lymph node metastasis; moreover, reduced miR-139 level was predominately occurred in late-stage HER2-oreexpression tumors. Collectively, our findings highlight miR-139-mediated suppression of CXCR4/p-Akt signaling and thereby affected mesenchymal stem-cell genesis, indicating its potential as a therapeutic target for invasive breast cancer.

Effects of emodin on intestinal mucosal barrier by the upregulation of miR-218a-5p expression in rats with acute necrotizing pancreatitis

Emodin is an effective component in rhubarb to cure intestinal dysfunction, but the specific mechanism remains unknown. This study aimed to evaluate the protective effects of emodin on intestinal dysfunction caused by acute severe pancreatitis and reveal the functional mechanism of emodin in the treatment of this condition. An acute severe pancreatitis model was prepared using taurocholate. In the treatment group, 50 mg/kg emodin was injected intravenously 2 h before the induction of acute severe pancreatitis at an interval of 8 h. After 24 h, the gene expression and protein levels of miR-218a-5p, RhoA, ROCK1, Akt, Notch1, Bax, Bcl-2, Fas, FasL, caspase-3, and caspase-9 were determined through reverse transcription polymerase chain reaction and Western blot analysis. The protein levels of occludin, zonula occludens-1 (ZO-1), and E-cadherin in the intestinal tract were also determined through Western blot analysis. The effects of miR-218a-5p on the apoptosis of rat intestinal epithelial cell-18 were observed through flow cytometry. The effects of emodin on intestinal cell apoptosis induced by acute severe pancreatitis were observed via TUNEL (terminal deoxynucleotidyl transferase dUTP nick-end labeling). Pathological changes in the pancreas and intestine of rats in each group were observed through hematoxylin and eosin staining. After 24 h of acute severe pancreatitis induced by taurocholate, emodin reduced the expression of miR-218a-5p in the intestinal tract; increased the expression of Notch1 and Bcl-2; decreased the expression levels of RhoA, ROCK1, Akt, Bax, Fas, FasL, caspase-3, and caspase-9; inhibited the intestinal cell apoptosis caused by acute severe pancreatitis; increased the protein expression levels of occludin, zonula occludens-1 (ZO-1), and E-cadherin in the intestinal tract; and alleviated intestinal dysfunction caused by acute severe pancreatitis. Emodin could regulate Notch1 and RhoA/ROCK pathways by regulating the miR-218a-5p expression in the intestine. It could also inhibit intestinal cell apoptosis induced by acute severe pancreatitis and improve the intestinal dysfunction caused by severe acute pancreatitis.

Circulating miRNAs as Biomarkers for Mitochondrial Neuro-Gastrointestinal Encephalomyopathy

Mitochondrial neurogastrointestinal encephalomyopathy (MNGIE) is an ultra-rare disease for which there are currently no validated outcome measures for assessing therapeutic intervention efficacy. The aim of this study was to identify a plasma and/or serum microRNA (miRNA) biomarker panel for MNGIE. Sixty-five patients and 65 age and sex matched healthy controls were recruited and assigned to one of four study phases: (i) discovery for sample size determination; (ii) candidate screening; (iii) candidate validation; and (iv) verifying the performance of the validated miRNA panel in four patients treated with erythrocyte-encapsulated thymidine phosphorylase (EE-TP), an enzyme replacement under development for MNGIE. Quantitative PCR (qPCR) was used to profile miRNAs in serum and/or plasma samples collected for the discovery, validation and performance phases, and next generation sequencing (NGS) analysis was applied to serum samples assigned to the candidate screening phase. Forty-one differentially expressed candidate miRNAs were identified in the sera of patients (p < 0.05, log₂ fold change > 1). The validation cohort revealed that of those, 27 miRNAs were upregulated in plasma and three miRNAs were upregulated in sera (p < 0.05). Through binary logistic regression analyses, five plasma miRNAs (miR-192-5p, miR-193a-5p, miR-194-5p, miR-215-5p and miR-34a-5p) and three serum miRNAs (miR-192-5p, miR-194-5p and miR-34a-5p) were shown to robustly distinguish MNGIE from healthy controls. Reduced longitudinal miRNA expression of miR-34a-5p was observed in all four patients treated with EE-TP and coincided with biochemical and clinical improvements. We recommend the inclusion of the plasma exploratory miRNA biomarker panel in future clinical trials of investigational therapies for MNGIE; it may have prognostic value for assessing clinical status.

MiR-4269 suppresses the tumorigenesis and development of pancreatic cancer by targeting ZEB1/OTX1 pathway

As one of the most prevalent malignant tumors, pancreatic cancer (PC) is a leading fatal cancer worldwide. Surging evidence has unraveled that miRNAs are involved in the occurrence and progression of multiple cancers, including PC. The tumor suppressor effects of miR-4269 have been certified in gastric carcinoma. However, the potential function of miR-4269 remains largely unclear, which drives us to identify the role of miR-4269 in PC development. In the present study, we determined the expression pattern of miR-4269 in PC cells and normal cells. Results of RT-qPCR analysis illuminated that miR-4269 expression level in PC cells was lower than that in normal cells. Functional assays demonstrated that up-regulation of miR-4269 obviously inhibited the proliferation, migration and invasion of PC cells. In order to elucidate the mechanism governing miR-4269 in PC, we carried out bioinformatics analysis and further experimental investigations. Our results validated that ZEB1 was a direct target of miR-4269. Additionally, ZEB1 activated the transcription of OXT1. More importantly, miR-4269 attenuated the expression level of OXT1 via targeting ZEB1. Ultimately, our findings confirmed that miR-4269 served as a cancer suppressor in PC through regulation of ZEB1/OTX1 pathway, which suggested that miR-4269 might represent a promising target for the clinical treatment of PC.

Noncoding RNAs Associated with Therapeutic Resistance in Pancreatic Cancer

Therapeutic resistance is an inevitable impediment towards effective cancer therapies. Evidence accumulated has shown that the signaling pathways and related factors are fundamentally responsible for therapeutic resistance via regulating diverse cellular events, such as epithelial-to-mesenchymal transition (EMT), stemness, cell survival/apoptosis, autophagy, etcetera. Noncoding RNAs (ncRNAs) have been identified as essential cellular components in gene regulation. The expression of ncRNAs is altered in cancer, and dysregulated ncRNAs participate in gene regulatory networks in pathological contexts. An in-depth understanding of molecular mechanisms underlying the modulation of therapeutic resistance is required to refine therapeutic benefits. This review presents an overview of the recent evidence concerning the role of human ncRNAs in therapeutic resistance, together with the feasibility of ncRNAs as therapeutic targets in pancreatic cancer.

MicroRNA-505, Suppressed by Oncogenic Long Non-coding RNA LINC01448, Acts as a Novel Suppressor of Glycolysis and Tumor Progression Through Inhibiting HK2 Expression in Pancreatic Cancer

Background: MicroRNAs (miRNAs) and long non-coding RNAs (lncRNAs) play vital regulatory roles in pancreatic cancer (PC) initiation and progression. We aimed to explore the biological functions and underlying mechanisms of miR-505-3p (miR-505) in PC.

Methods: We first screened miRNA expression profiles using microarray in PC tissues and normal tissues, and then studied the function and underlying mechanism of miR-505. Moreover, we evaluated the regulatory effect of lncRNA LINC01448 on miR-505.

Results: We demonstrated miR-505 that was significantly downregulated in PC tissues. We further revealed that miR-505 significantly inhibited cell proliferation, invasion, sphere formation, glucose consumption, and lactate production by targeting HK2. In addition, overexpression of miR-505 led to tumor growth inhibition in vivo, demonstrating that it acts as a tumor suppressor in PC. LINC01448 was identified as an oncogenic lncRNA that could reduce miR-505 expression. Subsequent studies confirmed that LINC01448 enhanced cell proliferation, invasion, sphere formation, glucose consumption, and lactate production by regulating the miR-505/HK2 pathway.

Conclusions: These findings demonstrated that miR-505, suppressed by LINC01448, could function as a key tumor suppressor by targeting HK2 in PC, elucidating an important role of the LINC01448/miR-505/HK2 pathway in regulating PC glycolysis and progression.

Prognostic value of low microRNA-34a expression in human gastrointestinal cancer: a systematic review and meta-analysis

Background

Mounting evidence shows that microRNA-34a (miR-34a) is involved in cancer prognosis. Therefore, we summarize the predictive role of miR-34a for survival in patients with gastrointestinal cancers (GICs).

Methods

All eligible studies were found by searching PubMed, Web of Science and EMBASE, and survival results were extracted. Then, the hazard ratio (HR) with the corresponding 95% confidence interval (CI) was calculated to evaluate the prognostic role of miR-34a in GICs. The association between miR-34a expression and clinicopathological characteristics was estimated by odds ratios (ORs) and 95% CIs.

Results

A total of 20 studies were included in this meta-analysis. For overall survival (OS), lower miR-34a expression could probably predict poorer outcome in GICs, with a pooled HR of 1.86 (95% CI: 1.52–2.28, P < 0.01). For disease-free survival (DFS), progression-free survival (PFS), and recurrence-free survival (RFS), lower miR-34a expression was related to worse DFS/PFS/RFS with a pooled HR of 1.86 (95% CI: 1.31–2.63, P  <  0.01). A significant relation of differentiation/TNM stage/lymphatic metastasis and the expression level of miR-34a was identified.

Conclusion

This meta-analysis revealed that lower miR-34a expression is significantly connected with worse OS and DFS/PFS/RFS in GIC patients. In addition, the miR-34a expression level is relatively lower in patients with lymph node metastasis than in patients without lymph node metastasis, and decreased miR-34a expression levels are linked to poor tumour differentiation and late TNM stage. MiR-34a may become a new factor for the prognosis prediction and progression of GICs.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12885-020-07751-y.

Radiation exposure triggers the malignancy of non‑small cell lung cancer cells through the activation of visfatin/Snail signaling

It is estimated that one-half of patients with non-small cell lung cancer (NSCLC) undergo radiotherapy worldwide. However, the outcome of radiotherapy alone is not always satisfactory. The aim of the present study was to evaluate the effects of radiotherapy on the malignancy of NSCLC cells. It was demonstrated that radiation therapy could increase the migration and invasion of NSCLC cells in vitro. Moreover, the upregulation of visfatin, a 52-kDa adipokine, mediated radiation-induced cell motility. A neutralizing antibody specific for visfatin blocked radiation-induced cell migration. Radiation and visfatin induced the expression of Snail, a key molecule that regulates epithelial to mesenchymal transition in NSCLC cells. Furthermore, visfatin positively regulated the mRNA stability of Snail in NSCLC cells, but had no effect on its protein degradation. This may be explained by visfatin-mediated downregulation of microRNA (miR)-34a, which was shown to bind the 3′ untranslated region of Snail mRNA to promote its decay. Collectively, these findings suggested that radiation could induce cell motility in NSCLC cells through visfatin/Snail signaling.

Protective Effects of Eicosapentaenoic Acid on the Glomerular Endothelium via Inhibition of EndMT in Diabetes

Diabetes-induced endothelial pathologies are hypothesized to lead to the progression of diabetic kidney disease (DKD). The endothelial to mesenchymal transition (EndMT) possibly induces fibrosis, leading to glomerulosclerosis in the kidney. Furthermore, this could lead to albuminuria in diabetic nephropathy due to glomerular endothelial dysfunction. Eicosapentaenoic acid (EPA), purified from fish oil, decreases inflammatory cytokine levels in glomerulonephritis. Here, we aimed at finding whether ethyl eicosapentaenoate (EPA-E) exerts renal protective effects via EndMT inhibition. To find out whether EPA inhibits EndMT in vitro, the changes in CD31 expression were studied in cultured mouse endothelial cells. The addition of the conditioned medium from the adipocyte culture significantly decreased the protein levels of CD31, while the addition of EPA-E partially reversed this inhibition. Further, EndMT inhibition by EPA-E treatment might occur via the inhibition of the protein kinase Cβ (PKCβ)/transforming growth factor-β (TGF-β)/plasminogen activator inhibitor-1 (PAI-1) signaling and not via microRNAs. Streptozotocin-induced diabetic mice fed a high-fat diet (60% from fat) exhibited mesangial expansion and albuminuria. Induction of EPA-E ameliorated the mesangial expansion and decreased albuminuria without affecting blood pressure, triglyceride and free fatty acid levels, and intraperitoneal glucose. These findings suggest that EPA-E exerts renal protective effects on endothelial cells, by normalizing EndMT followed by the PKCβ/TGF-β/PAI-1 signaling. Thus, EPA-E has the potential for imparting renal protection by regulating EndMT in DKD.

ASR490, a Small Molecule, Overrides Aberrant Expression of Notch1 in Colorectal Cancer

Notch1 activation triggers significant oncogenic signaling that manifests as enhanced metastatic potential and tumorigenesis in colorectal cancer. Novel small-molecule inhibitors, mainly plant-derived analogs, have low toxicity profiles and higher bioavailability. In this study, we have developed a small molecule, ASR490, by modifying structure of naturally occurring compound Withaferin A. ASR490 showed a growth-inhibitory potential by downregulating Notch1 signaling in HCT116 and SW620 cell lines. Docking studies and thermal shift assays confirmed that ASR490 binds to Notch1, whereas no changes in Notch2 and Notch3 expression were seen in colorectal cancer cells. Notch1 governs epithelial-to-mesenchymal transition signaling and is responsible for metastasis, which was abolished by ASR490 treatment. To further confirm the therapeutic potential of ASR490, we stably overexpressed Notch1 in HCT-116 cells and determined its inhibitory potential in transfected colorectal cancer (Notch1/HCT116) cells. ASR490 effectively prevented cell growth in both the vector (P = 0.005) and Notch1 (P = 0.05) transfectants. The downregulation of Notch1 signaling was evident, which corresponded with downregulation of mesenchymal markers, including N-cadherin and β-catenin and induction of E-cadherin in HCT-116 transfectants. Intraperitoneal administration of a 1% MTD dose of ASR490 (5 mg/kg) effectively suppressed the tumor growth in control (pCMV/HCT116) and Notch1/HCT116 in xenotransplanted mice. In addition, downregulation of Notch1 and survival signaling in ASR-treated tumors confirmed the in vitro results. In conclusion, ASR490 appears to be a potent agent that can inhibit Notch1 signaling in colorectal cancer.

Thymoquinone alleviates liver fibrosis via miR-30a-mediated epithelial-mesenchymal transition

Thymoquinone (TQ), the main active constituent of Nigella sativa seeds, has been shown to play a role in antioxidation, anti-inflammation, and antitumor. Recent studies have demonstrated that TQ contributes to the suppression of liver fibrosis. Abnormal activated epithelial-mesenchymal transition (EMT) promotes the activation of hepatic stellate cells (HSCs). However, whether the antifibrotic effects of TQ occur through inhibiting EMT is largely unknown. In this study, it was found that TQ ameliorated liver fibrosis and collagen accumulation in carbon tetrachloride (CCl4) mice. In vitro, TQ inhibited HSC activation including reduced proliferation, α-smooth muscle actin, and collagen. In addition, TQ markedly suppressed the EMT process, with enhanced E-cadherin and reduced desmin. Notably, snail family transcriptional repressor 1 (Snai1), the EMT master transcription factor, was obviously inhibited by TQ in vivo and in vitro. Further studies demonstrated that Snai1 was a target of microRNA-30a (miR-30a), which was upregulated by TQ. Interestingly, the effects of TQ on HSC activation and EMT were almost inhibited by miR-30a inhibitor. Collectively, we demonstrate that TQ inhibits HSC activation, at least in part, via regulation of miR-30a and Snai1. TQ upregulates miR-30a expression, resulting in a reduced Snai1 level as well as EMT process inactivation, which contributes to the inhibition of HSC activation. TQ may be a potential therapeutic agent for liver fibrosis.

Dual Regulation of miR-34a and Notch Signaling in Triple-Negative Breast Cancer by Antibody/miRNA Nanocarriers

Triple-negative breast cancer (TNBC) is an aggressive subtype of breast cancer that lacks expression of the three most common receptors present on other subtypes, leaving it unsusceptible to current targeted or hormonal therapies. In this study, we introduce an alternative treatment strategy for TNBC that exploits its overexpression of Notch1 receptors and its underexpression of the tumor suppressive microRNA (miRNA) miR-34a. Studies have shown that introducing mimics of miR-34a to TNBC cells effectively inhibits cancer growth, but miR-34a cannot be administered in the clinic without a carrier. To enable delivery of miR-34a to TNBC cells, we encapsulated miR-34a mimics in poly(lactic-co-glycolic acid) nanoparticles (NPs) that were functionalized with Notch1 antibodies to produce N1-34a-NPs. In addition to binding Notch1 receptors overexpressed on the surface of TNBC cells, the antibodies in this formulation enable suppression of Notch signaling through signal cascade interference. Herein, we present the results of in vitro experiments that demonstrate N1-34a-NPs can regulate Notch signaling and downstream miR-34a targets in TNBC cells to induce senescence and reduce cell proliferation and migration. These studies demonstrate that NP-mediated co-delivery of miR-34a and Notch1 antibodies is a promising alternative treatment strategy for TNBC, warranting further optimization and in vivo investigation in future studies.

Exosomes-Coated miR-34a Displays Potent Antitumor Activity in Pancreatic Cancer Both in vitro and in vivo

Purpose

MiR-34a, which acts as an important tumor suppressor gene, plays an important role in pancreatic cancer. However, the therapeutic application of miR-34a is limited by the lack of an effective delivery system. In the present study, we synthesize exosomes-coated miR-34a (exomiR-34a), and the anticancer effect of exomiR-34a was evaluated in pancreatic cancer.

Materials and Methods

An ultrasound approach was used to synthesize exomiR-34a, and its transfection efficiency was examined by confocal microscopy and flow cytometry. The level of miR-34a and its targeted gene Bcl-2 was detected by real-time quantitative PCR (qRT-PCR). MTT analysis was performed to determine the effect of exomiR-34a on the growth of pancreatic cancer cells. Annexin-V/PI double staining and Western blot analysis were carried out to determine the apoptosis of the pancreatic cancer cells. The xenograft nude mice model bearing human pancreatic cancer Panc28 cells was used to determine the antitumor effect of exomiR-34a in vivo.

Results

The exomiR-34a could cross the cell membrane efficiently, and downregulated the expression of the targeted gene Bcl-2. Treatment with exomiR-34a inhibited the growth of the pancreatic cancer cells significantly and the nanoparticles also induced apoptosis in cancer cells via affecting the expression of apoptotic-related genes. In vivo study using xenograft nude mice bearing Panc28 cancer cells revealed that exomiR-34a suppressed the growth of tumors significantly.

Conclusion

ExomiR-34a can inhibit the growth of pancreatic cancer both in vitro and in vivo. Targeting miR-34a is a promising strategy for the treatment of pancreatic cancer. ExomiR-34a has the potential to be developed as a novel anticancer agent for the treatment of human pancreatic malignancy.

Multifaceted Roles of DNA Methylation in Neoplastic Transformation, from Tumor Suppressors to EMT and Metastasis

Among the major mechanisms involved in tumorigenesis, DNA methylation is an important epigenetic modification impacting both genomic stability and gene expression. Methylation of promoter-proximal CpG islands (CGIs) and transcriptional silencing of tumor suppressors represent the best characterized epigenetic changes in neoplastic cells. The global cancer-associated effects of DNA hypomethylation influence chromatin architecture and reactivation of repetitive elements. Moreover, recent analyses of cancer cell methylomes highlight the role of the DNA hypomethylation of super-enhancer regions critically controlling the expression of key oncogenic players. We will first summarize some basic aspects of DNA methylation in tumorigenesis, along with the role of dysregulated DNA methyltransferases and TET (Ten-Eleven Translocation)-family methylcytosine dioxygenases. We will then examine the potential contribution of epimutations to causality and heritability of cancer. By reviewing some representative genes subjected to hypermethylation-mediated silencing, we will survey their oncosuppressor functions and roles as biomarkers in various types of cancer. Epithelial-to-mesenchymal transition (EMT) and the gain of stem-like properties are critically involved in cancer cell dissemination, metastasis, and therapeutic resistance. However, the driver vs passenger roles of epigenetic changes, such as DNA methylation in EMT, are still poorly understood. Therefore, we will focus our attention on several aspects of DNA methylation in control of EMT and metastasis suppressors, including both protein-coding and noncoding genes.

Synergistic effects of low‑dose chemotherapy and T cells in renal cell carcinoma

Renal cell carcinoma (RCC) is not sensitive to conventional radiotherapy and chemotherapy, and the effectiveness rate of molecular targeted therapy is low. Therefore, it is urgent to identify new treatment methods. Recently, adoptive T‑cell therapy has provided a new option for cancer treatment. Furthermore, low‑dose chemotherapy not only has no evident side effects and inhibitory effects on the human immune system, but can also enhance the immune activity of some effector cells. Therefore, it is surmised that the combination of different mechanisms of chemotherapy and immunotherapy could be a new treatment concept. In the present study, the effects of low‑dose chemotherapy combined with T cells in the treatment of renal cell carcinoma were explored using cytotoxicity assays, enzyme‑linked immunosorbent assay (ELISA), western blot analysis and flow cytometric analysis. The results revealed that low‑dose chemotherapy and T cells had synergistic effects on tumor cell elimination in vitro. The transforming growth factor (TGF)‑β signaling pathway may be involved in the inhibition of T‑cell functions. The targeted inhibition of TGF‑β signals may be a promising therapeutic strategy for the treatment of renal cancer. The present results provided a novel strategy for the combination of low‑dose chemotherapy and T cells to enhance the therapeutic efficacy of RCC treatment.

Cell-free microRNAs as Non-invasive Diagnostic and Prognostic Bio- markers in Pancreatic Cancer

Pancreatic cancer (PaC) is one of the most lethal cancers, with an increasing global incidence rate. Unfavorable prognosis largely results from associated difficulties in early diagnosis and the absence of prognostic and predictive biomarkers that would enable an individualized therapeutic approach. In fact, PaC prognosis has not improved for years, even though much efforts and resources have been devoted to PaC research, and the multimodal management of PaC patients has been used in clinical practice. It is thus imperative to develop optimal biomarkers, which would increase diagnostic precision and improve the post-diagnostic management of PaC patients. Current trends in biomarker research envisage the unique opportunity of cell-free microRNAs (miRNAs) present in circulation to become a convenient, non-invasive tool for accurate diagnosis, prognosis and prediction of response to treatment. This review analyzes studies focused on cell-free miRNAs in PaC. The studies provide solid evidence that miRNAs are detectable in serum, blood plasma, saliva, urine, and stool, and that they present easy-to-acquire biomarkers with strong diagnostic, prognostic and predictive potential.

mRNA expression profile analysis reveals a C-MYC/miR-34a pathway involved in the apoptosis of diffuse large B-cell lymphoma cells induced by Yiqichutan treatment

Diffuse large B-cell lymphoma (DLBCL) is the most common subtype of adult non-Hodgkin's lymphoma (NHL). While DLBCL is sensitive to chemotherapy, a certain percentage of patients with DLBCL experience relapse. Previous studies have indicated that Yiqichutan treatment, which was developed to treat NHL, can inhibit DLBCL cell growth, but the mechanism is not fully understood. The present study identified 991 differentially expressed mRNAs, with 498 upregulated and 493 downregulated (P<0.05), in SUDHL-6 cells exposed to Yiqichutan. The underlying pathways included the Jak/Stat and PI3K signaling pathways. In total, six representative mRNAs were selected for validation with reverse transcription-quantitative PCR (RT-qPCR), and a strong correlation was identified between the RT-qPCR results and microarray data. Since the transcription factor C-MYC is involved in both the Jak/Stat and PI3K signaling pathways, C-MYC and its associated microRNA (miR) were selected for further analysis. It was found that knockdown of C-MYC increased miR-34a expression levels, inhibited forkhead box P1 (Foxp1) expression levels and promoted DLBCL cell apoptosis. In addition, the miR-34a mimics further enhanced the role of C-MYC knockdown. It was demonstrated that, the expression levels of apoptotic factors Bax and poly (ADP-ribose) polymerase were significantly upregulated with C-MYC knockdown and miR-34a mimics in SUDHL-6 cells, while the Bcl2 expression level was significantly reduced. Moreover, Yiqichutan treatment increased miR-34a expression levels and induced apoptosis, as well as reducing Foxp1 expression level in SUDHL-6 cells. Therefore, the present results suggested that Yiqichutan treatment affected DLBCL cells via several signaling pathways. Furthermore, Yiqichutan may inhibit the proliferation of DLBCL cells by blocking the C-MYC/miR-34a signaling pathway.

MicroRNA-301a promotes pancreatic cancer invasion and metastasis through the JAK/STAT3 signaling pathway by targeting SOCS5

Pancreatic cancer is one of the most lethal digestive malignant tumors. We had previously found that microRNA-301a (miR-301a) is a oncogenic microRNA whose recognized conduce to nuclear factor-kappa B (NF-κB) activation in pancreatic cancer, yet the underlying mechanisms of miR-301a in promoting pancreatic cancer invasion and migration is obscure. In this work we found that high expression of miR-301a in human pancreatic cancer patients is related to poor survival. Overexpression of miR-301a enhances pancreatic cancer cell invasion, angiogenesis and migration, whereas inhibition of miR-301a suppresses pancreatic cancer cell invasion and reduces orthotopic pancreatic tumor growth and metastasis. Furthermore, suppressor of cytokine signaling 5 (SOCS5) is identified as a target gene of miR-301a. We found that miR-301a suppressed the expression of SOCS5 leads to janus kinase/signal transducer and activator of transcription 3 (JAK/STAT3) activation and is related to poor overall survival of pancreatic cancer patients. Taken together, our data show for the first time that the feedback loop between miR-301a and JAK/STAT3 pathway may play a significant role in pancreatic cancer invasion and metastasis. Targeting the loop may prove beneficial to prevent metastasis and provide a more effective therapeutic strategy for pancreatic cancer.

Mir34a constrains pancreatic carcinogenesis

Several studies have shown that over 70 different microRNAs are aberrantly expressed in pancreatic ductal adenocarcinoma (PDAC), affecting proliferation, apoptosis, metabolism, EMT and metastasis. The most important genetic alterations driving PDAC are a constitutive active mutation of the oncogene Kras and loss of function of the tumour suppressor Tp53 gene. Since the MicroRNA 34a (Mir34a) is a direct target of Tp53 it may critically contribute to the suppression of PDAC. Mir34a is epigenetically silenced in numerous cancers, including PDAC, where Mir34a down-regulation has been associated with poor patient prognosis. To determine whether Mir34a represents a suppressor of PDAC formation we generated an in vivo PDAC-mouse model harbouring pancreas-specific loss of Mir34a (Kras^G12D; Mir34a^Δ/Δ). Histological analysis of Kras^G12D; Mir34a^Δ/Δ mice revealed an accelerated formation of pre-neoplastic lesions and a faster PDAC development, compared to Kras^G12D controls. Here we show that the accelerated phenotype is driven by an early up-regulation of the pro-inflammatory cytokines TNFA and IL6 in normal acinar cells and accompanied by the recruitment of immune cells. Our results imply that Mir34a restrains PDAC development by modulating the immune microenvironment of PDAC, thus defining Mir34a restauration as a potential therapeutic strategy for inhibition of PDAC development.

miR‑539 suppresses the proliferation, migration, invasion and epithelial mesenchymal transition of pancreatic cancer cells through targeting SP1

MicroRNA (miR)‑539 has inhibitory effects on certain types of cancer, but its role in pancreatic cancer (PCa) remains unclear. The present study investigated the effects of miR‑539 on PCa, and aimed to determine possible therapeutic targets for the treatment of PCa. The expression of miR‑539 in PCa tissues, paired normal adjacent tissues and PCa cell lines (CAPAN‑2, BxPC3, CFPAC1, SW1990 and PANC1), and human non‑cancerous pancreatic cells (hTRET‑HPNE) was determined and compared. The effects of upregulation and downregulation of miR‑539 on proliferation, apoptosis, cell cycle, invasion, migration and epithelial‑mesenchymal transition (EMT) of PCa cells were investigated. Additionally, the target gene of miR‑539 was predicted and its effects on PCa cells were further investigated. The results revealed low expression of miR‑539 in PCa tissues and cell lines. Additionally, increasing miR‑539 expression inhibited the proliferation, migration, invasion and EMT of PCa cells and induced apoptosis by blocking G1 phase of the cell cycle, while reducing miR‑539 expression had the opposite results. Furthermore, specificity protein 1 (SP1) was found to be the target gene of miR‑539. SP1 promoted the proliferation, migration, invasion and EMT transformation of PCa cells, but these effects were reversed by high expression of miR‑539. Additionally, miR‑539 suppressed the proliferation, metastasis, invasion and EMT transformation of PCa cells through targeting SP1. Therefore, miR‑539 overexpression may contribute toward development of novel therapeutic strategies for PCa in the future.

A Systemic Review on the Regulatory Roles of miR-34a in Gastrointestinal Cancer

MicroRNAs (miRNAs) are a class of endogenous non-coding single-stranded small-molecule RNAs that regulate gene expression by repressing target messenger RNA (mRNA) translation or degrading mRNA. miR-34a is one of the most important miRNAs participating in various physiological and pathological processes. miR-34a is abnormally expressed in a variety of tumors. The roles of miR-34a in gastrointestinal cancer (GIC) draw lots of attention. Numerous studies have demonstrated that dysregulated miR-34a is closely related to the proliferation, differentiation, migration, and invasion of tumor cells, as well as the diagnosis, prognosis, treatment, and chemo-resistance of tumors. Thus, we systematically reviewed the abnormal expression and regulatory roles of miR-34a in GICs including esophageal cancer (EC), gastric cancer (GC), colorectal cancer (CRC), hepatocellular carcinoma (HCC), pancreatic cancer (PC), and gallbladder cancer (GBC). It may provide a profile of versatile roles of miR-34a in GICs.

MicroRNAs Targeting MYC Expression: Trace of Hope for Pancreatic Cancer Therapy. A Systematic Review

Background

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies and a major health problem worldwide. There were no major advances in conventional treatments in inhibiting tumor progression and increasing patient survival time. In order to suppress mechanisms responsible for tumor cell development such as those with oncogenic roles, more advanced therapeutic strategies should be sought. One of the most important oncogenes of pancreatic cancer is the MYC gene. The overexpression of MYC can activate many tumorigenic processes such as cell proliferation and pancreatic cancer cell invasion. MiRNAs are important molecules that are confirmed by targeting mRNA transcripts to regulate the expression of the MYC gene. Therefore, restoring MYC-repressing miRNAs expression tends to be an effective method of treating MYC-driven cancers.

Objective

The purpose of this study was to identify all validated microRNAs targeting C-MYC expression to inhibit PDAC progression by conducting a systematic review.

Methods

In this systematic review study, the papers published between 2000 and 2020 in major online scientific databases including PubMed, Scopus, and Web of Science were screened, following inclusion and exclusion criteria. We extracted all the experimental studies that showed miRNAs could target the expression of the MYC gene in PDAC.

Results

Eight papers were selected from a total of 89 papers. We found that six miRNAs (Let-7a, miR-145, miR-34a, miR-375, miR-494, and miR-148a) among the selected studies were validated for targeting MYC gene and three of them confirmed Let-7a as a direct MYC expression regulator in PC cells. Finally, we summarized the latest shreds of evidence of experimentally validated miRNAs targeting the MYC gene with respect to PDAC’s therapeutic potential.

Conclusion

Restoring the expression of MYC-repressing miRNAs tends to be an effective way to treat MYC-driven cancers such as PDAC. Several miRNAs have been proposed to target this oncogene via bioinformatics tools, but only a few have been experimentally validated for pancreatic cancer cells and models. Further studies should be conducted to find the interaction network of miRNA-MYC to develop more successful therapeutic strategies for PC, using the synergistic effects of these miRNAs.

Non-coding RNAs in Pancreatic Ductal Adenocarcinoma

Non-coding RNAs (ncRNAs) are reported to be expressed in human cancers, including pancreatic ductal adenocarcinoma (PDAC). These ncRNAs affect the growth, migration and invasion of tumor cells by regulating cell cycle and apoptosis, as well as playing important roles in epigenetic processes, transcription and post-transcriptional regulation. It is still unclear whether alterations in ncRNAs influence PDAC development and progression. Because of this, analysis based on existing data on ncRNAs, which are crucial for modulating pancreatic tumorigenesis, will be important for future research on PDAC. Here, we summarize ncRNAs with tumor-promoting functions: HOTAIR, HOTTIP, MALAT1, lncRNA H19, lncRNA PVT1, circ-RNA ciRS-7, circ-0030235, circ-RNA_100782, circ-LDLRAD3, circ-0007534, circRHOT1, circZMYM2, circ-IARS, circ-RNA PDE8A, miR-21, miR-155, miR-221/222, miR-196b, miR-10a. While others including GAS5, MEG3, and lncRNA ENST00000480739, has_circ_0001649, miR-34a, miR-100, miR-217, miR-143 inhibit the proliferation and invasion of PDAC. Hence, we summarize the functions of ncRNAs in the occurrence, development and metastasis of PDAC, with the goal to provide guidance in the clinical diagnosis and treatment of PDAC.

MiR-34a-5p Inhibits Proliferation, Migration, Invasion and Epithelial-mesenchymal Transition in Esophageal Squamous Cell Carcinoma by Targeting LEF1 and Inactivation of the Hippo-YAP1/TAZ Signaling Pathway

Background: Our previous studies reported that lymphoid enhancer-binding factor 1 (LEF1) was upregulated in esophageal squamous cell carcinoma (ESCC) and the positive expression of LEF1 was correlated with aberrant clinicopathological characteristics in ESCC patients. However, the upstream mechanism of regulating LEF1 is not clear fully. In this study, we explored the role of miR-34a-5p in ESCC and the possible regulatory mechanism. Methods: In this study, we applied western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), bioinformatics analysis, a luciferase reporter assay, and a series of functional assays to show the potential role of miR-34a-5p in regulating LEF1 in ESCC. Results: By various functional assays, we demonstrated that LEF1 promoted proliferation, migration, invasion and epithelial-mesenchymal transition (EMT) in ESCC cells. By bioinformatics analysis and luciferase reporter assay, miR-34a-5p was identified for directly targeting LEF1. Then we investigated the expression of miR-34a-5p and LEF1 in ESCC. As a result, miR-34a-5p was downregulated while LEF1 was upregulated in ESCC tissue and cell lines. Overexpression of miR-34a-5p could inhibit proliferation, migration, invasion and EMT of ESCC cells. The rescue experiment showed that re-expression of LEF1 reversed the suppressive effect caused by miR-34a-5p. At last, we found that miR-34a-5p could suppress Hippo-YAP1/TAZ signaling pathway in ESCC. Conclusion: Our results indicate miR-34a-5p inhibits proliferation, migration, invasion and EMT in ESCC by targeting LEF1 and suppressing the Hippo-YAP1/TAZ signaling pathway, which may provide a new antitumor strategy to delay ESCC progress.

Decitabine and all-trans retinoic acid synergistically exhibit cytotoxicity against elderly AML patients via miR-34a/MYCN axis

This study aimed to investigate the efficacy and mechanism of decitabine (DAC) and all-trans retinoic acid (ATRA) in elderly acute myeloid leukemia (AML) patients and cultured cells. Our clinical trial enrolled 36 elderly patients who were judged ineligible for conventional chemotherapy, receiving DAC and ATRA regimen (DAC 20 mg/m² days 1-5; ATRA 20 mg/m² days 4-28 in the first cycle and days 1-28 in the subsequent cycle). Treated with a median of 3 cycles (range 1-6), 44.4 % of patients achieved complete remission (CR), 11.1 % achieved CR with incomplete peripheral count recovery (CRi) and 13.9 % achieved partial remission (PR). The median overall survival (OS) was 12.1 months; the 1-year and 2-year OS rates were 49.6 % and 17.2 %. In addition, our in vitro studies indicated that the antineoplastic activities of DAC and ATRA mutually reinforced, which induced growth inhibition, cell cycle arrest and apoptosis of AML cells. Meanwhile, we found DAC and ATRA inhibited DNMT1, activated miR-34a via promoter hypomethylation, down-regulated its target MYCN and thus exerted a synergistic antineoplastic effect. In conclusion, DAC plus ATRA regimen might be effective and well-tolerated for elderly patients partially through modulating miR-34a/MYCN axis.

Interplay among SNAIL Transcription Factor, MicroRNAs, Long Non-Coding RNAs, and Circular RNAs in the Regulation of Tumor Growth and Metastasis

SNAIL (SNAI1) is a zinc finger transcription factor that binds to E-box sequences and regulates the expression of genes. It usually acts as a gene repressor, but it may also activate the expression of genes. SNAIL plays a key role in the regulation of epithelial to mesenchymal transition, which is the main mechanism responsible for the progression and metastasis of epithelial tumors. Nevertheless, it also regulates different processes that are responsible for tumor growth, such as the activity of cancer stem cells, the control of cell metabolism, and the regulation of differentiation. Different proteins and microRNAs may regulate the SNAIL level, and SNAIL may be an important regulator of microRNA expression as well. The interplay among SNAIL, microRNAs, long non-coding RNAs, and circular RNAs is a key event in the regulation of tumor growth and metastasis. This review for the first time discusses different types of regulation between SNAIL and non-coding RNAs with a focus on feedback loops and the role of competitive RNA. Understanding these mechanisms may help develop novel therapeutic strategies against cancer based on microRNAs.

Potential of Exosomal microRNA-200b as Liquid Biopsy Marker in Pancreatic Ductal Adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is a highly malignant tumor entity, characterized by rapid disease progression, early metastatic dissemination, and late diagnosis at advanced tumor stages. Recently, we explored the clinical impact of several microRNAs (miR) associated with proliferation, epithelial-to-mesenchymal transition (EMT), and chemoresistance in tissue and blood serum specimens of PDAC patients. Here, we evaluated the potential of these miRs as diagnostic and prognostic biomarkers in PDAC in serum exosomes and their respective EpCAM-positive (epithelial cell adhesion molecule) subset. Expression analysis by RT-qRT-PCR (real-time quantitative reverse transcription polymerase chain reaction) revealed an overexpression of miR-200b and miR-200c in serum exosomes of PDAC patients as compared to healthy controls (p < 0.001; p = 0.024) and patients with chronic pancreatitis (p = 0.005; p = 0.19). Receiver operating characteristic (ROC) curve analysis showed that a biomarker panel consisting of miR-200b and miR-200c from total and EpCAM-positive serum exosomes enhanced the diagnostic accuracy of carbohydrate antigen 19-9 (CA.19-9) to 97% (p < 0.0001). Univariate survival analysis revealed a correlation between shorter overall survival (OS) and high expression of miR-200c in total serum exosomes (p = 0.038) and miR-200b in EpCAM-positive serum exosomes (p = 0.032), whereas EpCAM exosomal miR-200b was also indicative of shorter OS in the subgroup of patients treated with curative intent (p = 0.013). Multivariate survival analysis showed that miR-200b derived from EpCAM-positive serum exosomes might serve as an independent prognostic factor in PDAC (p = 0.044). Our findings indicate a potential role of exosomal miR-200 as diagnostic and prognostic liquid biopsy marker in PDAC and call for validation in a larger, multicenter setting.

SNHG7 accelerates cell migration and invasion through regulating miR-34a-Snail-EMT axis in gastric cancer

Small nucleolar RNA host gene 7 (SNHG7) is a newly recognized oncogenic Long non-coding RNA (lncRNA) in most human cancers. In gastric cancer, SNHG7 has been suggested to enhance cell proliferation and suppressed apoptosis through down-regulating P15 and P16 expression, but the effect of SNHG7 on gastric cancer cell migration and invasion was still unknown. In our study, we aimed to estimate the relationship between SNHG7 expression and clinical and pathological characteristics, and explore the effect of SNHG7 on gastric cancer cell migration and invasion. In our study, the levels of SNHG7 expression in gastric cancer tissues and cell lines were severally higher than in normal adjacent tissues and gastric mucosal epithelial cells. Moreover, high SNHG7 expression was positively correlated with TNM stage, depth of invasion, lymph-node metastasis and distant metastasis in gastric cancer patients. Furthermore, the multivariate Cox proportional hazard analysis further showed high SNHG7 expression was an independent poor prognostic factor for overall survival in gastric cancer patients. The studies in vitro revealed that SNHG7 directly binds to miR-34a and negatively regulates miR-34a expression, and SNHG7 enhances gastric cancer cell migration and invasion through suppressing miR-34a-Snail-EMT axis. In conclusion, SNHG7 functions as oncogenic lncRNA in gastric cancer and may be a potential therapeutic target for gastric cancer patients.Abbreviations: lncRNA: Long non-coding RNA; SNHG7: Small nucleolar RNA host gene 7; EMT: Epithelial mesenchymal transition; TNM: Tumor-Lymph Node-Metastasis.

miR-331-3p functions as an oncogene by targeting ST7L in pancreatic cancer

Pancreatic cancer (PC) is a highly invasive tumor with early metastasis and poor prognosis, yet the mechanisms for tumor progression have not been fully elucidated. Emerging evidence indicates that microRNA-331-3p (miR-331-3p) plays an important role in the progression of diverse human cancers. Here, we found that miR-331-3p was significantly upregulated in tumor specimens of PC patients and PC cell lines. Functional studies showed that downregulation of miR-331-3p inhibited PC cell proliferation and epithelial-mesenchymal transition (EMT)-mediated metastasis in vitro. Furthermore, suppression of tumorigenicity 7 like (ST7L) was identified as a novel target gene of miR-331-3p. Tumor promotion effects of miR-331-3p were partially reversed by ST7L re-expression. In addition, miR-331-3p antagomir suppressed PC tumor growth and metastasis via upregulation of ST7L in xenograft mice. In summary, these results demonstrate that miR-331-3p is a tumor-promoting microRNA (miRNA) in PC cells and a promising biomarker for PC.

Circ-ASH2L promotes tumor progression by sponging miR-34a to regulate Notch1 in pancreatic ductal adenocarcinoma

BACKGROUND

Circular RNAs (circRNAs) have recently been shown to play important roles in different tumors. However, their detailed roles and regulatory mechanisms in pancreatic ductal adenocarcinoma (PDAC) are not well understood. This study aimed to identify enriched circRNAs and detect their functions and mechanisms in PDAC cells and tissues.

METHODS

circRNA-ASH2L (circ-ASH2L) was identified by circRNA microarray studies based on previous studies, and further detected in PDAC cells and samples by qRT-PCR. The functions of circ-ASH2L were identified by transwell, EdU, cell cycle or Tube formation assays. The regulatory mechanisms of circ-ASH2L were explored by WB, RIP, FISH, dual-luciferase assays, RNA pulldown or other assays.

RESULTS

We identified a circRNA (circ-ASH2L) based on our previous studies, detected its expression in different malignant cells and found that circ-ASH2L was highly expressed in pancreatic cells or tumor tissues and correlated with tumor malignancy. Further studies revealed that circ-ASH2L promoted tumor invasion, proliferation and angiogenesis by regulating miR-34a, thus regulate Notch 1 expression. Circ-ASH2L served as a miRNA sponge for miR-34a and promoted tumor progression in vivo. Finally, we analyzed circ-ASH2L expression in clinical tissues and found that high circ-ASH2L expression was correlated with lymphatic invasion and TNM stage and was an independent risk factor for pancreatic patient survival.

CONCLUSIONS

circ-ASH2L play an important role in tumor invasion, and high circ-ASH2L may be a useful marker of PDAC diagnosis or progression.

MicroRNA in Pancreatic Cancer: From Biology to Therapeutic Potential

Pancreatic cancer is one of the most aggressive malignancies, accounting for more than 45,750 deaths annually in the U.S. alone. The aggressive nature and late diagnosis of pancreatic cancer, coupled with the limitations of existing chemotherapy, present the pressing need for the development of novel therapeutic strategies. Recent reports have demonstrated a critical role of microRNAs (miRNAs) in the initiation, progression, and metastasis of cancer. Furthermore, aberrant expressions of miRNAs have often been associated with the cause and consequence of pancreatic cancer, emphasizing the possible use of miRNAs in the effective management of pancreatic cancer patients. In this review, we provide a brief overview of miRNA biogenesis and its role in fundamental cellular process and miRNA studies in pancreatic cancer patients and animal models. Subsequent sections narrate the role of miRNA in, (i) cell cycle and proliferation; (ii) apoptosis; (iii) invasions and metastasis; and (iv) various cellular signaling pathways. We also describe the role of miRNA's in pancreatic cancer; (i) diagnosis; (ii) prognosis and (iii) therapeutic intervention. Conclusion section describes the gist of review with future directions.

The basics of epithelial-mesenchymal transition (EMT): A study from a structure, dynamics, and functional perspective

Epithelial-mesenchymal transition (EMT) is a key step in transdifferentiation process in solid cancer development. Forthcoming evidence suggest that the stratified program transforms polarized, immotile epithelial cells to migratory mesenchymal cells associated with enhancement of breast cancer stemness, metastasis, and drug resistance. It involves primarily several signaling pathways, such as transforming growth factor-β (TGF-β), cadherin, notch, plasminogen activator protein inhibitor, urokinase plasminogen activator, and WNT/beta catenin pathways. However, current understanding on the crosstalk of multisignaling pathways and assemblies of key transcription factors remain to be explored. In this review, we focus on the crosstalk of signal transduction pathways linked to the current therapeutic and drug development strategies. We have also performed the computational modeling on indepth the structure and conformational dynamic studies of regulatory proteins and analyze molecular interactions with their associate factors to understand the complicated process of EMT in breast cancer progression and metastasis. Electrostatic potential surfaces have been analyzed that help in optimization of electrostatic interactions between the protein and its ligand. Therefore, understanding the biological implications underlying the EMT process through molecular biology with biocomputation and structural biology approaches will enable the development of new therapeutic strategies to sensitize tumors to conventional therapy and suppress their metastatic phenotype.

Connecting sex differences, estrogen signaling, and microRNAs in cardiac fibrosis

Sex differences are evident in the pathophysiology of heart failure (HF). Progression of HF is promoted by cardiac fibrosis and no fibrosis-specific therapies are currently available. The fibrotic response is mediated by cardiac fibroblasts (CFs), and a central event is their phenotypic transition to pro-fibrotic myofibroblasts. These myofibroblasts may arise from various cellular origins including resident CFs and epicardial and endothelial cells. Both female subjects in clinical studies and female animals in experimental studies generally present less cardiac fibrosis compared with males. This difference is at least partially considered attributable to the ovarian hormone 17β-estradiol (E2). E2 signals via estrogen receptors to regulate genes are involved in the fibrotic response and myofibroblast transition. Besides protein-coding genes, E2 also regulates transcription of microRNA that modulate cardiac fibrosis. Sex dimorphism, E2, and miRNAs form multi-level regulatory networks in the pathophysiology of cardiac fibrosis, and the mechanism of these networks is not yet fully deciphered. Therefore, this review is aimed at summarizing current knowledge on sex differences, E2, and estrogen receptors in cardiac fibrosis, emphasizing on microRNAs and myofibroblast origins. KEY MESSAGES: • E2 and ERs regulate cardiac fibroblast function. • E2 and ERs may distinctly affect male and female cardiac fibrosis pathophysiology. • Sex, E2, and miRNAs form multi-level regulatory networks in cardiac fibrosis. • Sex-dimorphic and E2-regulated miRNAs affect mesenchymal transition.

MicroRNA-34a inhibits epithelial-mesenchymal transition of lens epithelial cells by targeting Notch1

Posterior capsule opacification (PCO) is a common long-term complication of modern cataract surgery. The epithelial-mesenchymal transition (EMT) of lens epithelial cells (LECs) is a crucial process in the development of PCO. The purpose of this study is to investigate the role of microRNA-34a (miR-34a) in the regulation of EMT and its target gene. Human LECs were treated with TGFβ2 to induce EMT as a model for PCO. The mRNA levels of miR-34a and EMT markers were examined by real-time quantitative polymerase chain reaction (qPCR). The expression level of miR-34a was downregulated, whereas that of Notch1 was upregulated in TGFβ2-induced EMT of LECs. Overexpression of miR-34a by transfection with miR-34a inhibited EMT of LECs and reduced the expression of Notch1; while, inhibition of miR-34a upregulated the expression of both Notch1 and its ligand Jagged1 in LECs. Luciferase reporter assays revealed that Notch1 gene was direct target of miR-34a. Moreover, DAPT, a specific inhibitor of Notch signaling pathway, reversed LEC-EMT. In addition, the expression level of miR-34a was downregulated, whereas that of Notch1 was upregulated in capsular opacification from cataract samples. MiR-34a can negatively regulate EMT of LECs by targeting Notch1. Therefore, miR-34a/Notch1 could serve as a potential therapeutic approach for the treatment of PCO.