The involvement of lncRNAs in the development and progression of pancreatic cancer

Role of microRNA-505 during tumor progression and metastasis

Late diagnosis of cancer in advanced stages due to the lack of screening methods is considered as the main cause of poor prognosis and high mortality rate among these patients. Therefore, it is necessary to investigate the molecular tumor biology in order to introduce biomarkers that can be used in cancer screening programs and early diagnosis. MicroRNAs (miRNAs) have key roles in regulation of the cellular pathophysiological processes. Due to the high stability of miRNAs in body fluids, they are widely used as the non-invasive tumor markers. According to the numerous reports about miR-505 deregulation in a wide range of cancers, we investigated the role of miR-505 during tumor progression. It was shown that miR-505 mainly has the tumor suppressor functions through the regulation of signaling pathways, chromatin remodeling, and cellular metabolism. This review has an effective role in introducing miR-505 as a suitable marker for the early cancer diagnosis.

Silencing long noncoding RNA LINC01133 suppresses pancreatic cancer through regulation of microRNA-1299-dependent IGF2BP3

The deregulation of long noncoding RNAs (lncRNAs) holds great potential in the treatment of multiple cancers, including pancreatic cancer (PC). However, the specific molecular mechanisms by which LINC01133 contributes to pancreatic cancer remain unknown. Subsequent to bioinformatics analysis, we predicted and analyzed differentially expressed lncRNAs, microRNAs, and genes in pancreatic cancer. We determined the expression patterns of LINC01133, miR-1299, and insulin-like growth factor 2 mRNA binding protein 3 (IGF2BP3) in pancreatic cancer cells, and validated their interactions through luciferase reporter and RNA immunoprecipitation assays. We implemented loss-of-function and gain-of-function experiments for LINC01133, miR-1299, and IGF2BP3 to assay their potential effects on pancreatic cancer cell functions. We observed high expression of LINC01133 and IGF2BP3, but low expression of miR-1299, in pancreatic cancer cells. Furthermore, we found that LINC01133 enhances IGF2BP3 through binding with miR-1299. Silencing LINC01133 or IGF2BP3 and/or overexpressing miR-1299 limited pancreatic cancer cell proliferation, invasion, epithelial-mesenchymal transition, and suppressed tumorigenic abilities in mice lacking T cells (nude mice). Overall, our findings identified that silencing LINC01133 downregulates IGF2BP3 by upregulating miR-1299 expression, ultimately leading to the prevention of pancreatic cancer.

A prognostic and immunotherapy effectiveness model for pancreatic adenocarcinoma based on cuproptosis-related lncRNAs signature

Pancreatic adenocarcinoma (PAAD) results in one of the deadliest solid tumors with discouraging clinical outcomes. Growing evidence suggests that long non-coding RNAs (lncRNAs) play a crucial role in altering the growth, prognosis, migration, and invasion of pancreatic cancer cells. Cuproptosis is a novel type of cell death induced by copper (Cu) and is associated with mitochondrial respiration during the tricarboxylic acid cycle. However, the relationship between lncRNAs related to cuproptosis and PAAD is poorly studied. In this study, we investigated the association between a signature of cuproptosis-related lncRNAs and the diagnosis of PAAD. Genomic data and clinical information were obtained using the TCGA dataset, while cuproptosis-related genes (CRGs) from previous studies. Co-expression analysis was utilized to identify lncRNAs associated with cuproptosis. We developed and verified a prognostic risk model following a classification of patients into high- and low-risk categories. The prediction capacity of the risk model was assessed using a number of methods including Kaplan-Meier analysis, receiver operating characteristic (ROC) curves, nomograms, and principal component analysis (PCA). Furthermore, differentially expressed genes (DEGs) were used to perform functional enrichment analyses, and to examine the behaviors of various risk groups in terms of immune-related activities and medication sensitivity. We identified 7 cuproptosis-related lncRNA signatures, including CASC19, FAM83A-AS1, AC074099.1, AC007292.2, AC026462.3, AL358944.1, and AC009019.1, as overall survival (OS) predictors. OS and progression-free survival (PFS) showed significant differences among patients in different risk groups. Independent prognostic analysis revealed that the cuproptosis-related lncRNA signatures can independently achieve patient prognosis. The risk model demonstrated strong predictive ability for patient outcomes, as evidenced by ROC curves, nomograms, and PCA. Higher tumor mutation burden (TMB) and lower tumor immune dysfunction and exclusion (TIDE) scores were observed in the high-risk group. Additionally, the low-risk group was hypersensitive to 3 anti-cancer medications, whereas the high-risk group was hypersensitive to one. A prognostic risk model with a good predictive ability based on cuproptosis-related lncRNAs was developed, providing a theoretical basis for personalized treatment and immunotherapeutic responses in pancreatic cancer.

BHLHE40, a potential immune therapy target, regulated by FGD5-AS1/miR-15a-5p in pancreatic cancer

Pancreatic cancer, as one of the neoplasms with the highest degree of malignancy, has become a main disease of concerns in recent years. BHLHE40, a critical transcription factor for remodeling of the tumor immune microenvironment, has been described to be substantially increased in a variety of tumor-associated immune cells. Nevertheless, the pro-cancer biological functions and underlying molecular mechanisms of BHLHE40 for pancreatic cancer and its unique microenvironment are unclear. Hereby, we investigated the pro-oncogenic role of BHLHE40 in the pancreatic cancer microenvironment by bioinformatics analysis and cell biology experiments and determined that the expression of BHLHE40 was obviously elevated in pancreatic cancer tissues than in adjacent normal tissues. In parallel, Kaplan-Meier survival analysis unveiled that lower expression of BHLHE40 was strongly associated with better prognosis of patients. Receiver operating characteristic (ROC) curve analysis confirmed the accuracy of the BHLHE40-related prediction model. Subsequent, spearman correlation analysis observed that higher expression of BHLHE40 might be involved in immunosuppression of pancreatic cancer. Silencing of BHLHE40 could inhibit proliferation, invasion, and apoptosis of pancreatic cancer in vitro and in vivo, implying that BHLHE40 is expected to be a potential therapeutic target for pancreatic cancer. In addition, we explored and validated the FGD5-AS1/miR-15a-5p axis as a potential upstream regulatory mode for high expression of BHLHE40 in pancreatic cancer. In summary, our data showed that ceRNA involved in the regulation of BHLHE40 contributes to the promotion of immunosuppressive response in pancreatic and is expected to be a diagnostic marker and potential immunotherapeutic target for pancreatic cancer.

Pancreatic Cancer and Detection Methods

The pancreas is a vital organ with exocrine and endocrine functions. Pancreatitis is an inflammation of the pancreas caused by alcohol consumption and gallstones. This condition can heighten the risk of pancreatic cancer (PC), a challenging disease with a high mortality rate. Genetic and epigenetic factors contribute significantly to PC development, along with other risk factors. Early detection is crucial for improving PC outcomes. Diagnostic methods, including imagining modalities and tissue biopsy, aid in the detection and analysis of PC. In contrast, liquid biopsy (LB) shows promise in early tumor detection by assessing biomarkers in bodily fluids. Understanding the function of the pancreas, associated diseases, risk factors, and available diagnostic methods is essential for effective management and early PC detection. The current clinical examination of PC is challenging due to its asymptomatic early stages and limitations of highly precise diagnostics. Screening is recommended for high-risk populations and individuals with potential benign tumors. Among various PC screening methods, the N-NOSE plus pancreas test stands out with its high AUC of 0.865. Compared to other commercial products, the N-NOSE plus pancreas test offers a cost-effective solution for early detection. However, additional diagnostic tests are required for confirmation. Further research, validation, and the development of non-invasive screening methods and standardized scoring systems are crucial to enhance PC detection and improve patient outcomes. This review outlines the context of pancreatic cancer and the challenges for early detection.

CASC9 potentiates gemcitabine resistance in pancreatic cancer by reciprocally activating NRF2 and the NF-κB signaling pathway

Gemcitabine resistance is a frequently occurring and intractable obstacle in pancreatic cancer treatment. However, the underlying mechanisms require further investigation. Adaptive regulation of oxidative stress and aberrant activation of the NF-κB signaling pathway are associated with resistance to chemotherapy. Here, we found that gemcitabine upregulated the expression of CASC9 in a dose-dependent manner, partially via induction of reactive oxygen species, whereas inhibition of CASC9 expression enhanced gemcitabine-induced oxidative stress and apoptosis in pancreatic cancer cells. Furthermore, suppression of CASC9 level inhibited the expression of NRF2 and the downstream genes NQO1 and HO-1, and vice versa, indicating that CASC9 forms a positive feedback loop with NRF2 signaling and modulates the level of oxidative stress. Silencing CASC9 attenuated NF-κB pathway activation in pancreatic cancer cells and synergistically enhanced the cytotoxic effect of gemcitabine chemotherapy in vivo. In conclusion, our findings suggest that CASC9 plays a key role in driving resistance to gemcitabine through a reciprocal loop with the NRF2-antioxidant signaling pathway and by activating NF-κB signaling. Our study reveals potential targets that can effectively reverse resistance to gemcitabine chemotherapy.

Resistance to Gemcitabine in Pancreatic Ductal Adenocarcinoma: A Physiopathologic and Pharmacologic Review

Pancreatic ductal adenocarcinoma (PDAC) is a very aggressive tumor with a poor prognosis and inadequate response to treatment. Many factors contribute to this therapeutic failure: lack of symptoms until the tumor reaches an advanced stage, leading to late diagnosis; early lymphatic and hematic spread; advanced age of patients; important development of a pro-tumoral and hyperfibrotic stroma; high genetic and metabolic heterogeneity; poor vascular supply; a highly acidic matrix; extreme hypoxia; and early development of resistance to the available therapeutic options. In most cases, the disease is silent for a long time, andwhen it does become symptomatic, it is too late for ablative surgery; this is one of the major reasons explaining the short survival associated with the disease. Even when surgery is possible, relapsesare frequent, andthe causes of this devastating picture are the low efficacy ofand early resistance to all known chemotherapeutic treatments. Thus, it is imperative to analyze the roots of this resistance in order to improve the benefits of therapy. PDAC chemoresistance is the final product of different, but to some extent, interconnected factors. Surgery, being the most adequate treatment for pancreatic cancer and the only one that in a few selected cases can achieve longer survival, is only possible in less than 20% of patients. Thus, the treatment burden relies on chemotherapy in mostcases. While the FOLFIRINOX scheme has a slightly longer overall survival, it also produces many more adverse eventsso that gemcitabine is still considered the first choice for treatment, especially in combination with other compounds/agents. This review discusses the multiple causes of gemcitabine resistance in PDAC.

Role of long non-coding RNAs in development and progression of pancreatic cancer

Pancreatic cancer is a kind of digestive tract malignant tumor that has high malignancy and is difficult to diagnose and treat. Recent studies have proved that long non-coding RNAs (lncRNAs) can mediate tumor genesis, proliferation, migration, and metastasis by regulating epigenetic modification, alternative splicing, transcription, and protein translation. LncRNAs play an important role in the occurrence and development of pancreatic cancer. In this review, we review the role of lncRNAs in pancreatic cancer to provide possible diagnostic and therapeutic targets for the treatment of this malignancy.

ABHD11-AS1: An Emerging Long Non-Coding RNA (lncRNA) with Clinical Significance in Human Malignancies

The aberrant expression of lncRNAs has been linked to the development and progression of different cancers. One such lncRNA is ABHD11 antisense RNA 1 (ABHD11-AS1), which has recently gained attention for its significant role in human malignancies. ABHD11-AS1 is highly expressed in gastric, lung, breast, colorectal, thyroid, pancreas, ovary, endometrium, cervix, and bladder cancers. Several reports highlighted the clinical significance of ABHD11-AS1 in prognosis, diagnosis, prediction of cancer progression stage, and treatment response. Significantly, the levels of ABHD11-AS1 in gastric juice had been exhibited as a clinical biomarker for the assessment of gastric cancer, while its serum levels have prognostic potential in thyroid cancers. The ABHD11-AS1 has been reported to exert oncogenic effects by sponging different microRNAs (miRNAs), altering signaling pathways such as PI3K/Akt, epigenetic mechanisms, and N6-methyladenosine (m⁶A) RNA modification. In contrast, the mouse homolog of AHD11-AS1 (Abhd11os) overexpression had exhibited neuroprotective effects against mutant huntingtin-induced toxicity. Considering the emerging research reports, the authors attempted in this first review on ABHD11-AS1 to summarize and highlight its oncogenic potential and clinical significance in different human cancers. Lastly, we underlined the necessity for future mechanistic studies to unravel the role of ABHD11-AS1 in tumor development, prognosis, progression, and targeted therapeutic approaches.

Exosomal-long non-coding RNAs journey in colorectal cancer: Evil and goodness faces of key players

Exosomes are nano-vesicles (NVs) secreted by cells and take part in cell-cell communications. Lately, these exosomes were proved to have dual faces in cancer. Actually, they can contribute to carcinogenesis through epithelial-mesenchymal transition (EMT), angiogenesis, metastasis and tumor microenvironment (TME) of various cancers, including colorectal cancer (CRC). On the other hand, they can be potential targets for cancer treatment. CRC is one of the most frequent tumors worldwide, with incidence rates rising in the recent decades. In its early stage, CRC is asymptomatic with poor treatment outcomes. Therefore, finding a non-invasive, early diagnostic biomarker tool and/or suitable defender to combat CRC is mandatory. Exosomes provide enrichment and safe setting for their cargos non-coding RNAs (ncRNAs) and proteins, whose expression levels can be upregulated ordown-regulated in cancer. Hence, exosomes can be used as diagnostic and/or prognostic tools for cancer. Moreover, exosomes can provide a novel potential therapeutic modality for tumors via loading with specific chemotherapeutic agents, with the advantage of possible tumor targeting. In this review, we will try to collect and address recent studies concerned with exosomes and their cargos' implications for CRC diagnosis and/or hopefully, treatment.

Long Non-Coding RNAs in Epithelial-Mesenchymal Transition of Pancreatic Cancer

Non-coding RNAs (ncRNAs), or RNA molecules that do not code for proteins, are generally categorized as either small or long ncRNA (lncRNA) and are involved in the pathogenesis of several diseases including many cancers. Identification of a large number of ncRNAs could help to elucidate previously unknown mechanisms in phenotype regulation. Some ncRNAs are encapsulated by extracellular vesicles (EVs) and transferred to recipient cells to regulate cellular processes, including epigenetic and post-transcriptional regulations. Recent studies have uncovered novel molecular mechanisms and functions of lncRNAs in pancreatic ductal adenocarcinoma (PDAC), one of the most intractable cancers that is highly invasive and metastatic. As the epithelial-mesenchymal transition (EMT) triggers tumor cell invasion and migration, clarification of the roles of lncRNA in EMT and tumor cell stemness would be critical for improving diagnostic and therapeutic approaches in metastatic cancers. This review provides an overview of relevant studies on lncRNA and its involvement with EMT in PDAC. Emerging knowledge offers evidence for the dysregulated expression of lncRNAs and essential insights into the potential contribution of both lncRNAs and EVs in the pathogenesis of PDAC. Future directions and new clinical applications for PDAC are also discussed.

FGD5‑AS1 is an oncogenic lncRNA in pancreatic cancer and regulates the Wnt/β‑catenin signaling pathway via miR‑577

The objective of the present study was to clarify the expression characteristics of long non-coding RNA (lncRNA) FGD5 antisense RNA 1 (FGD5-AS1) in pancreatic cancer, as well as its biological function and underlying mechanism. Reverse transcription-quantitative polymerase chain reaction (RT-qPCR) was utilized for the detection of FGD5-AS1 and microRNA (miR)-577 expression levels in pancreatic cancer tissues. Transfection was performed to upregulate or downregulate FGD5-AS1 in pancreatic cancer cell lines. MTT and Transwell assays were then utilized to detect the proliferation, migration and invasion of cancer cells, respectively. Subsequently, dual-luciferase reporter gene assay, RNA immunoprecipitation assay, RNA pull-down assay, RT-qPCR, western blotting, and Pearson's correlation analysis were employed to confirm the regulatory relationships among FGD5-AS1, miR-577, low-density lipoprotein receptor-related protein 6 (LRP6) and β-catenin. Western blotting was employed to determine the expression levels of Axin2, cyclin D1 and c-Myc. The expression level of FGD5-AS1 was upregulated in pancreatic cancer tissues and cell lines. FGD5-AS1 knockdown inhibited pancreatic cancer cell proliferation, migration and invasion. By contrast, miR-577 was significantly inhibited in pancreatic cancer cells and tissues; its downregulation promoted pancreatic cancer cell proliferation, migration and invasion, and reversed the effects of FGD5-AS1 knockdown on pancreatic cancer cells. In addition, it was revealed that miR-577 was a target of FGD5-AS1, and FGD5-AS1 could modulate the expression levels of LRP6, β-catenin, Axin2, cyclin D1 and c-Myc via suppressing miR-577. In conclusion, in pancreatic cancer, highly expressed FGD5-AS1 activated the Wnt/β-catenin signaling and promoted cancer cell proliferation, migration and invasion via suppression of miR-577.

Knockdown of LINC00657 inhibits the viability, migration and invasion of pancreatic cancer cells by regulating the miR-520h/CKS1B axis

Long non-coding RNA LINC00657 has a critical role in multiple cancers. The aim of the present study was to investigate the regulatory effect of LINC00657 in pancreatic cancer (PC) and reveal its molecular mechanism of function. The expression levels of LINC00657 and microRNA (miR)-520h were detected by reverse transcription-quantitative PCR in PC tissues and cell lines. MTT, wound healing and Transwell assays were used to detect cell viability, migration and invasion, respectively. Dual-luciferase reporter assay was utilized to examine the relationship between LINC00657 and miR-520h and that between miR-520h and cyclin-dependent kinases regulatory subunit 1 (CKS1B). Western blotting was performed to detect CKS1B expression. The expression levels of LINC00657 and CKS1B were enhanced and miR-520h expression level was reduced in PC tissues and cell lines compared with adjacent normal tissues or HPDE6 cells. LINC00657 knockdown decreased the viability, migration and invasion of PC cells. Additionally, LINC00657 targeted miR-520h and negatively modulated miR-520h expression. Furthermore, miR-520h overexpression inhibited the viability, migration and invasion of PC cells. In addition, miR-520h targeted CKS1B and reversely regulated CKS1B expression. miR-520h inhibition and CKS1B overexpression alleviated the inhibition effect of LINC00657 knockdown on the viability, migration and invasion of PACA-2 PC cells. In conclusion, the results of the present study demonstrated that LINC00657 knockdown repressed the viability, migration and invasion of PC cells via targeting the miR-520h/CKS1B axis, which may offer a future target for PC therapy.

LncRNA TP53TG1 Promotes the Growth and Migration of Hepatocellular Carcinoma Cells via Activation of ERK Signaling

Long non-coding RNA (lncRNA) TP53 target 1 (TP53TG1) was discovered as a TP53 target gene. TP53TG1 has been reported as having dual roles by exerting tumor-suppressive and oncogenic activities that vary depending on the cancer type. Yet, the role of TP53TG1 in hepatocellular carcinoma (HCC) is not fully understood. In this study, we performed both gain- and loss-of-function studies to determine the biological role of TP53TG1 in HCC. We found that the knockdown of TP53 in HCC cells caused the upregulation of TP53TG1. Furthermore, we found that the knockdown of TP53TG1 not only suppressed HCC cell proliferation and migration, but also reduced intrinsic ERK signaling. In contrast, the overexpression of TP53TG1 increased ERK activation and enhanced HCC proliferation. In conclusion, our study reveals an oncogenic role of TP53TG1 in HCC, which provides a novel insight into the cell-type-specific function of TP53TG1 in HCC.

NEAT1 boosts the development of thoracic 1 aortic aneurysm through targeting miR-324-5p/RAN

BACKGROUND

Long non-coding RNAs (lncRNAs) have been identified in multiple cancers. Recently, NEAT1 is found to be up regulated in cervical cancer. Since the relationship between NEAT1 and thoracic aortic aneurysm (TAA) has not been clarified, our study focused on the role of NEAT1 in TAA.

METHODS

Bioinformatics, RNA pulls down and luciferase reporter assay were used to discover and determine miR-324-5p to be a target of NEAT1. RT-qPCR was used to examine NEAT1, RAN and miR-324-5p expression.

RESULTS

NEAT1 was up-regulated in TAA patients, as well as HAoSMC and HA-VSMC cells. Down-regulation of NEAT1 could inhibit the proliferative abilities while promoting apoptosis of TAA cells. MiR-324-5p expression was down-regulated in both TAA tissues and cells. Then, RAN was selected out as a target of miR-324-5p. More interestingly, miR-324-5p had inhibitory effects on malignant behaviors of TAA cells. RAN was negatively related with miR-324-5p while positively correlated with NEAT1 in the tissues. Finally, the data of rescue assays manifested that RAN up-regulation could countervail the influence of down-regulation of NEAT1 on TAA cells.

CONCLUSION

NEAT1 could contribute to the malignant behaviors of TAA cells by targeting miR-324-5p/RAN. NEAT1 might be an underlying target for the therapy of TAA.

Role of epithelial-mesenchymal transition in chemoresistance in pancreatic ductal adenocarcinoma

Pancreatic cancer (PC) is the seventh leading cause of cancer death worldwide. The vast majority of patients who have PC develop metastases, resulting in poor treatment effects. Although great progress in therapeutic approaches has been achieved in recent decades, extensive drug resistance still persists, representing a major hurdle to effective anticancer therapy for pancreatic ductal adenocarcinoma (PDAC). Therefore, there is an urgent need to better understand the drug resistance mechanisms and develop novel treatment strategies to improve patient outcomes. Numerous studies suggest that chemoresistance is closely related to epithelial-mesenchymal transition (EMT) of PDAC cells. Thus, this article summarizes the impact of EMT on PDAC from the perspective of chemotherapy resistance and discusses the possible novel applications of EMT inhibition to develop more effective drugs against PDAC.

Long non‑coding RNA PCED1B‑AS1 promotes pancreatic ductal adenocarcinoma progression by regulating the miR‑411‑3p/HIF‑1α axis

An increasing number of studies have shown that long non‑coding RNAs (lncRNAs) are crucially involved in tumorigenesis. However, the biological functions, underlying mechanisms and clinical value of lncRNA PC‑esterase domain containing 1B‑antisense RNA 1 (PCED1B‑AS1) in pancreatic ductal adenocarcinoma (PDAC) have not been determined, to the best of our knowledge. In the present study, the expression of PCED1B‑AS1, microRNA (miR)‑411‑3p and hypoxia inducible factor (HIF)‑1α mRNA in 47 cases of PDAC tissues were detected using reverse transcription‑quantitative (RT‑q)PCR. Moreover, the effects of PCED1B‑AS1 on the biological behaviors of PDAC cells were assessed using Cell Counting Kit‑8, EdU staining and Transwell assays. Bioinformatics analysis, RT‑qPCR, western blotting, dual luciferase reporter gene and RNA immunoprecipitation assays were performed to determine the regulatory relationships between PCED1B‑AS1, miR‑411‑3p and HIF‑1α. We demonstrated that PCED1B‑AS1 was significantly upregulated in PDAC tumor tissues, and its expression was associated with advanced Tumor‑Node‑Metastasis stage and lymph node metastasis. PCED1B‑AS1 knockdown inhibited PDAC cell proliferation, invasion as well as epithelial‑mesenchymal transition (EMT) in vitro. Mechanistically, PCED1B‑AS1 was shown to target miR‑411‑3p, resulting in the upregulation of HIF‑1α. In conclusion, PCED1B‑AS1 expression was upregulated in PDAC tissues and cells, and it participated in promoting the proliferation, invasion and EMT of cancer cells by modulating the miR‑411‑3p/HIF‑1α axis.

Long noncoding RNAs: role and contribution in pancreatic cancer

Noncoding RNAs are proclaimed to be expressed in various cancer types and one such type is found to be pancreatic ductal adenocarcinoma (PDAC). The long noncoding RNAs (LncRNAs) affect the migration, invasion, and growth of tumor cells by playing important roles in the process of epigenesis, post-transcription, and transcriptional regulation along with the maintenance of apoptosis and cell cycle. It is quite subtle whether the alterations in lncRNAs would impact PDAC progression and development. This review throws a spotlight on the lncRNAs associated with tumor functions: MALAT-1, HOTAIR, HOXA13, H19, LINC01559, LINC00460, SNHG14, SNHG16, DLX6-AS1, MSC-AS1, ABHD11-AS1, DUXAP8, DANCR, XIST, DLEU2, etc. are upregulated lncRNAs whereas GAS5, HMlincRNA717, MIAT, LINC01111, lncRNA KCNK15-AS1, etc. are downregulated lncRNAs inhibiting the invasion and progression of PDAC. These data provided helps in the assessment of lncRNAs in the development, metastasis, and occurrence of PDAC and also play a vital role in the evolution of biomarkers and therapeutic agents for the treatment of PDAC.

LINC00894 Enhances the Progression of Breast Cancer by Sponging miR-429 to Regulate ZEB1 Expression

PURPOSE

Long non-coding RNAs (lncRNAs) are known to regulate tumorigenesis. Although breast cancer tissues show a high expression of LINC00894, its specific biological role in breast cancer progression is still unknown. In this study, lncRNA microarray was used to analyze the lncRNA expression in breast cancer tissues, and LINC00894 was selected for further analysis.

MATERIALS AND METHODS

Expression of LINC00894 in 45 pairs of breast cancer tissues and normal tissues obtained from patients with breast cancer was assessed by quantitative reverse transcription-PCR, while proliferation and invasion of breast cancer cells were assessed using a Cell Counting Kit-8 (CCK-8), EdU assay, colony formation experiment, and transwell assays. A dual-luciferase reporter gene assay and bioinformatics analysis were employed to detect potential targets of LINC00894. Additionally, RNA Binding Protein Immunoprecipitation (RIP) and Western blot assays were utilized to clarify its interaction and roles in the regulation of breast cancer progression.

RESULTS

High expression of LINC00894 was observed in breast cancer cells, and its overexpression significantly expedited cell proliferation and invasion. Moreover, LINC00894 positively regulated the expression of ZEB1 by competitively binding to miR-429.

CONCLUSION

Taken together, these results suggest that LINC00894 competitively binds to miR-429 to mediate ZEB1 expression; consequently, it is implicated to play a role in the progression of breast cancer.

Long Intergenic Nonprotein Coding RNA 173 Inhibits Tumor Growth and Promotes Apoptosis by Repressing Sphingosine Kinase 1 Protein Expression in Pancreatic Cancer

Pancreatic cancer is a common malignant tumor worldwide. Extensive studies have been conducted on the functional role of long noncoding RNAs in pancreatic cancer. In this study, long intergenic nonprotein coding RNA 173 (LINC00173) was highly expressed in pancreatic cancer tissues. In vitro functional experiments showed that LINC00173 overexpression inhibited the proliferation and invasion of pancreatic cancer cells and promoted cell apoptosis in MIA PaCa-2 and PANC-1 cells. RNA sequencing analysis and Western blot assays demonstrated that LINC00173 reduced the expression of sphingosine kinase 1 (SPHK1) and then inhibited the protein expression of activated phospho-protein kinase B (AKT) and NF-κB. In vivo functional assays also revealed that LINC00173 inhibited the growth of pancreatic cancer xenografts, repressed cell proliferation, promoted cell apoptosis, and inhibited SPHK1 expression. The combined results of this study indicate that LINC00173 inhibits pancreatic cancer progression by repressing SPHK1 expression. Improving LINC00173 may represent a therapeutic strategy for pancreatic cancer in the future.

Long non-coding RNA TP73-AS1 promotes pancreatic cancer growth and metastasis through miRNA-128-3p/GOLM1 axis

BACKGROUND

Previous studies have suggested that long non-coding RNAs (lncRNA) TP73-AS1 is significantly upregulated in several cancers. However, the biological role and clinical significance of TP73-AS1 in pancreatic cancer (PC) remain unclear.

AIM

To investigate the role of TP73-AS1 in the growth and metastasis of PC.

METHODS

The expression of lncRNA TP73-AS1, miR-128-3p, and GOLM1 in PC tissues and cells was detected by quantitative real-time polymerase chain reaction. The bioinformatics prediction software ENCORI was used to predict the putative binding sites of miR-128-3p. The regulatory roles of TP73-AS1 and miR-128-3p in cell proliferation, migration, and invasion abilities were verified by Cell Counting Kit-8, wound-healing, and transwell assays, as well as flow cytometry and Western blot analysis. The interactions among TP73-AS1, miR-128-3p, and GOLM1 were explored by bioinformatics prediction, luciferase assay, and Western blot.

RESULTS

The expression of TP73-AS1 and miRNA-128-3p was dysregulated in PC tissues and cells. High TP73-AS1 expression was correlated with a poor prognosis. TP73-AS1 silencing inhibited PC cell proliferation, migration, and invasion in vitro as well as suppressed tumor growth in vivo. Mechanistically, TP73-AS1 was validated to promote PC progression through GOLM1 upregulation by competitively binding to miR-128-3p.

CONCLUSION

Our results demonstrated that TP73-AS1 promotes PC progression by regulating the miR-128-3p/GOLM1 axis, which might provide a potential treatment strategy for patients with PC.

Nanomedicine to Overcome Multidrug Resistance Mechanisms in Colon and Pancreatic Cancer: Recent Progress

The development of drug resistance is one of the main causes of cancer treatment failure. This phenomenon occurs very frequently in different types of cancer, including colon and pancreatic cancers. However, the underlying molecular mechanisms are not fully understood. In recent years, nanomedicine has improved the delivery and efficacy of drugs, and has decreased their side effects. In addition, it has allowed to design drugs capable of avoiding certain resistance mechanisms of tumors. In this article, we review the main resistance mechanisms in colon and pancreatic cancers, along with the most relevant strategies offered by nanodrugs to overcome this obstacle. These strategies include the inhibition of efflux pumps, the use of specific targets, the development of nanomedicines affecting the environment of cancer-specific tissues, the modulation of DNA repair mechanisms or RNA (miRNA), and specific approaches to damage cancer stem cells, among others. This review aims to illustrate how advanced nanoformulations, including polymeric conjugates, micelles, dendrimers, liposomes, metallic and carbon-based nanoparticles, are allowing to overcome one of the main limitations in the treatment of colon and pancreatic cancers. The future development of nanomedicine opens new horizons for cancer treatment.

Role of Curcumin in Regulating Long Noncoding RNA Expression in Cancer

Phytochemicals are various compounds produced by plants. There is growing evidence on their potential health effects. Some of these compounds are considered as traditional medicines and used as painkillers, anti-inflammatory agents, and for other applications. One of these phytochemicals is curumin, a natural polyphenol derived from the turmeric plant (Curcuma longa L.). Curcumin is widely used as a food coloring, preservative and condiment. It has also been shown to have antioxidative and anti-inflammatory effects. Moreover, there is growing evidence that curcumin alters long noncoding RNAs (lncRNAs) in many kinds of cancer. These noncoding RNAs can cause epigenetic modulation in the expression of several genes. This study reviews reports of curcumin effects on lncRNAs in lung, prostate, colorectal, breast, pancreatic, renal, gastric, and ovarian cancers.

Long non-coding RNA PART1 predicts a poor prognosis and promotes the malignant progression of pancreatic cancer by sponging miR-122

BACKGROUND AND OBJECTIVES

Long non-coding RNA (lncRNA) prostate androgen-regulated transcript 1 (PART1) was previously shown to exert an oncogenic role in several human cancers. However, whether PART1 is associated with the malignant progression of pancreatic cancer remains unclear. In the current study, we aimed to identify the role and potential mechanism of PART1 in pancreatic cancer.

METHODS

qRT-PCR was applied to detect PART1 expression in 45 cases of pancreatic cancer patients. The chi-square test was performed to assess the association between PART1 expression and clinicopathologic features, and Kaplan-Meier method was applied to evaluate overall survival. In vitro CCK-8, transwell invasion, and flow cytometry assays were applied to detect the effects of PART1 on cell proliferation, invasion, and apoptosis, respectively. Luciferase reporter and RNA immunoprecipitation assays were used to identify the regulatory mechanism between PART1 and miR-122.

RESULTS

PART1 expression was upregulated in pancreatic cancer tissues and cell lines. High PART1 expression was closely correlated with tumor size, T classification, clinical stage, and vascular invasion, and predicted a poor overall survival. PART1 knockdown significantly suppressed cell proliferation and invasion abilities of pancreatic cancer but promoted cell apoptosis. PART1 was found to serve as a molecular sponge of miR-122, and miR-122 inhibition partially reversed the inhibitory phenotypes of PART1 knockdown on pancreatic cancer cells.

CONCLUSIONS

PART1 promotes the malignant progression of pancreatic cancer by sponging miR-122. The PART1/miR-122 axis might be a promising target for anticancer therapy in patients with pancreatic cancer.

Long Noncoding RNA CERS6-AS1 Accelerates the Proliferation and Migration of Pancreatic Cancer Cells by Sequestering MicroRNA-15a-5p and MicroRNA-6838-5p and Modulating HMGA1

OBJECTIVES

As one of the most aggressive human tumors, pancreatic cancer (PC) is accompanied by poor treatment and prognosis. Although emerging evidence has highlighted the importance of long noncoding RNAs in multiple cancers, the specific regulatory roles mostly remain obscure. Our aim was to disclose the role of CERS6 antisense RNA 1 (CERS6-AS1) in PC.

METHODS

Quantitative real-time polymerase chain reaction analysis was used to examine the expression of CERS6-AS1 in PC cell lines. Western blot analysis was used to assess the protein levels of high-mobility group AT-hook 1 (HMGA1). Colony formation, 5-ethynyl-20-deoxyuridine, transwell, and wound healing assays were performed to detect the functions of CERS6-AS1 on PC development. In addition, RNA pull-down, RNA immunoprecipitation, and luciferase reporter assays were implemented to delve into the regulatory mechanism of CERS6-AS1 in PC.

RESULTS

CERS6-AS1 was significantly upregulated in PC. CERS6-AS1 silence obviously inhibited cell proliferation and migration in PC. Furthermore, CERS6-AS1 sponged microRNA-15a-5p (miR-15a-5p) and microRNA-6838-5p (miR-6838-5p) to regulate HMGA1. Moreover, rescue assays verified that CERS6-AS1 was involved in cell proliferation and migration in PC via targeting miR-15a-5p/miR-6838-5p/HMGA1 axis.

CONCLUSIONS

CERS6-AS1 enhanced HMGA1 expression to contribute to the progression of PC by sequestering miR-15a-5p and miR-6838-5p.

YY1-inudced activation of lncRNA DUXAP8 promotes proliferation and suppresses apoptosis of triple negative breast cancer cells through upregulating SAPCD2

Double homeobox A pseudogene 8 (DUXAP8) belongs to long non-coding RNAs (lncRNAs), which has been proven to promote the biological processes of multiple human cancers. Triple-negative breast cancer (TNBC) is the leading cause of cancer-related death in women worldwide. However, the specific role of lncRNA DUXAP8 and its underlying mechanism in TNBC remains to be unclear. We detected the expression of DUXAP8 in TNBC cells through qRT-PCR analysis. The effects of DUXAP8 silencing on TNBC cell proliferation and apoptosis were identified using CCK-8 assay, EdU assay, flow cytometry analysis and TUNEL assay. The downstream microRNA (miRNA) and messenger RNA (mRNA) of DUXAP8 were searched out through bioinformatics analysis and mechanism experiments. Rescue assays were conducted to verify the involvement of suppressor APC domain containing 2 (SAPCD2) in DUXAP8-mediated TNBC cell proliferation and apoptosis. DUXAP8 was highly expressed in TNBC cells compared to that in normal breast cells. Knockdown of DUXAP8 inhibited TNBC cell proliferation and accelerated cell apoptosis. DUXAP8 interacted with miR-29a-3p and thus enhanced the expression of SAPCD2. Moreover, YY1 transcription factor could bind to DUXAP8 promoter to activate the transcription of DUXAP8. YY1-induced transcriptional activation of DUXAP8 promotes TNBC cell growth through miR-29a-3p/SAPCD2 axis.

Long non-coding RNA CERS6-AS1 facilitates the oncogenicity of pancreatic ductal adenocarcinoma by regulating the microRNA-15a-5p/FGFR1 axis

The long non-coding RNA CERS6 antisense RNA 1 (CERS6-AS1) has critical regulatory roles in breast cancer progression. Here, we determined CERS6-AS1 expression in pancreatic ductal adenocarcinoma (PDAC) and the roles of CERS6-AS1 in PDAC carcinogenesis. The mechanisms underlying the regulatory actions of CERS6-AS1 in PDAC cells were elucidated in detail. CERS6-AS1 expression was evidently increased in PDAC tissues and cell lines. Patients with PDAC having high CERS6-AS1 expression had shorter overall survival periods than those having low CERS6-AS1 expression. Functionally, the knockdown of CERS6-AS1 attenuated the proliferation, migration, and invasion and stimulated apoptosis of PDAC cells in vitro. Additionally, CERS6-AS1 depletion decreased PDAC tumor growth in vivo. Mechanistically, CERS6-AS1 could competitively bind to microRNA-15a-5p (miR-15a-5p) and effectively work as a molecular sponge in PDAC cells, resulting in the upregulation of fibroblast growth factor receptor 1 (FGFR1), a direct target of miR-15a-5p. Rescue experiments revealed that miR-15a-5p downregulation or FGFR1 restoration rescued the effects of CERS6-AS1 knockdown on the behaviors of PDAC cells. In conclusion, CERS6-AS1 promoted the oncogenicity of PDAC by serving as a competing endogenous RNA to sequester miR-15a-5p and increase FGFR1 expression, which highlights the potential of the CERS6-AS1/miR-15a-5p/FGFR1 pathway as an effective target for cancer therapy.

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.

Increased SPHK1 and HAS2 Expressions Correlate to Poor Prognosis in Pancreatic Cancer

OBJECTIVE

SPHK1 and HAS2 have been reported to play important roles in tumorigenesis and development. However, their expression and prognostic value in pancreatic cancer (PC) remain unclear. This study is aimed at investigating the expression of SPHK1 and HAS2 on the prognosis of pancreatic cancer.

MATERIALS AND METHODS

The expression of SPHK1 and HAS2 in pancreatic cancer tissues was analyzed through TCGA and GTEx databases and validated by qRT-PCR and Western blot in pancreatic cancer cell lines. χ 2 test was used to explore the correlation of the SPHK1 and HAS2 expressions with clinical characteristics. Kaplan-Meier survival analysis and ROC curve were used to evaluate the prognostic and diagnostic roles of SPHK1 and HAS2 in pancreatic cancer. Additionally, Spearman correlation analysis was applied to assess the correlation between the SPHK1 and HAS2 in pancreatic cancer. GO analysis and KEGG analysis were applied to explore the possible signaling pathway that SPHK1 and HAS2 coregulated genes mediated.

RESULTS

The expression of SPHK1 and HAS2 was markedly upregulated in pancreatic cancer tissue and cell lines, respectively. Furthermore, there was a significant positive correlation between SPHK1 and HAS2 expressions. ROC curves showed that SPHK1 combine with HAS2 has good diagnostic value in pancreatic cancer patients with 85% sensitivity and 99.4% specificity. Kaplan-Meier analysis showed that increased expression of SPHK1 and HAS2 was significantly associated with short overall survival (OS) of pancreatic cancer patients. GO and KEGG results revealed that SPHK1 and HAS2 mainly involved cell proliferation and invasion mediated by extracellular matrix- (ECM-) receptor interaction, focal adhesion, and PI3K-AKT signaling pathways.

CONCLUSIONS

Overexpression of SPHK1 and HAS2 could be important markers for the prognosis of pancreatic cancer.

Hypoxia-induced lncRNA CASC9 enhances glycolysis and the epithelial-mesenchymal transition of pancreatic cancer by a positive feedback loop with AKT/HIF-1α signaling

Increasing evidence indicates the dysregulations and pivotal roles of lncRNAs in the development and progression of various cancers, including pancreatic cancer. Enhanced glycolytic flux and epithelial-to-mesenchymal transition (EMT) have been considered as important factors in driving the malignance of pancreatic cancer. Here, we sought to evaluate the biological role and involved mechanism of lncRNA CASC9 (CASC9) in pancreatic cancer. Our present study showed that CASC9 was upregulated in various pancreatic cancer cell lines. Loss- and gain-of function of CASC9 demonstrated its critical roles in promoting the glycolysis and EMT phenotypes of pancreatic cancer. Moreover, knockdown of CASC9 inhibited the tumorigenicity and metastasis in vivo. Additionally, our findings showed that hypoxia induced the expression of CASC9 and enhanced the binding of HIF-1α to its promoter. We also demonstrated that the positive feedback loop of CASC9 and the AKT/HIF-1α signaling cascade partially mediated this biological process. Altogether, our results suggest that CASC9 promotes the glycolysis and EMT of pancreatic cancer by a positive feedback loop with AKT/HIF-1α signaling, which is synergistically enhanced by the tumor hypoxic niche. Our study will provide potential therapeutic targets for treating pancreatic cancer.

Exosomal long non-coding RNAs in the diagnosis and oncogenesis of pancreatic cancer

Extracellular vesicles, specifically exosomes, play a significant role as an extracellular messenger through their transporting cargo. Of particular interest are the potential roles they play in pancreatic cancer, one of the leading causes of cancer-related mortality worldwide. Pancreatic Ductal Adenocarcinoma displays high chemo-resistance and metastatic ability, which may be influenced by cancer-derived exosomes carrying proteins, lipids and RNA. To date, among the most extensively examined exosomal molecular cargo there are long non-coding RNAs (lncRNAs) that, despite the increasing interest in their role and functions, are relatively poorly understood compared to other RNA transcripts. Nevertheless, we have witnessed an increasing interest for lncRNAs roles and functions in the past decade. For example, lncRNAs have been investigated as potential biomarkers for diagnosing pancreatic cancer and may have a role as therapeutics targets for precision medicine, but may also directly intervene in tumour progression features such as metastasis, epithelial to mesenchymal transition and resistance of cancer cells towards chemotherapy agents. The function of lncRNAs within various cancer exosomes is still undefined. In this review, we summarize the current knowledge on pancreatic cancer-derived exosome specific lncRNAs having prominent roles in genome integrity, pancreatic cancer progression and in other oncogenic hallmarks.

Long noncoding RNA HEIH depletion depresses esophageal carcinoma cell progression by upregulating microRNA-185 and downregulating KLK5

Numerous studies have reported the association of long non-coding RNAs (lncRNAs) in cancers, yet the function of lncRNA high expressed in hepatocellular carcinoma (HEIH) in esophageal carcinoma (EC) has seldom been explored. Here, we aimed to explore the mechanism of HEIH on EC via microRNA-185 (miR-185)/kallikrein-related peptidase 5 (KLK5) modulation. Cancer and non-tumoral tissues were collected, in which HEIH, miR-185 and KLK5 expression were detected, as well as their correlations. Also, the relation between the prognosis of EC patients and HEIH/miR-185/KLK5 expression was clarified. EC cells (KYSE-30 and TE-1) were screened for subsequent gain- and loss-of-function assays and their biological functions were further monitored. Tumor volume and weight in EC mice were also measured. Results from this study indicated that HEIH and KLK5 were elevated and miR-185 was declined in EC. The positive correlation was seen in HEIH and KLK5 expression, while the negative correlation was observed in HEIH or KLK5 and miR-185 expression. High HEIH and KLK5 indicated worse prognosis and high miR-185 suggested better prognosis of EC patients. Depleting HEIH or restoring miR-185 suppressed the malignant phenotypes of EC cells, and delayed tumor growth in EC mice. HEIH was found to bind with miR-185 to regulate KLK5 expression. Overexpressing KLK5 alone promoted EC cell progression while up-regulating miR-185 reversed such effects on EC cells. Collectively, we reveal that HEIH depletion dampens EC progression by upregulating miR-185 and downregulating KLK5, which provides novel treatments for EC.

Noncoding RNAs in drug-resistant pancreatic cancer: A review

Pancreatic cancer is the fourth-leading cause of cancer-related deaths and is expected to be the second-leading cause of cancer-related deaths in Europe and the United States by 2030. The high fatality rate of pancreatic cancer is ascribed to untimely diagnosis, early metastasis and limited responses to both chemotherapy and radiotherapy. Although gemcitabine, 5-fluorouracil and some other drugs can profoundly improve patient prognosis, most pancreatic cancer patients eventually develop drug resistance, leading to poor clinical outcomes. The underlying mechanisms of pancreatic cancer drug resistance are complicated and inconclusive. Interestingly, accumulating evidence has demonstrated that different noncoding RNAs (ncRNAs), such as microRNAs (miRNAs), long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs), play a crucial role in pancreatic cancer resistance to chemotherapy reagents. In this paper, we systematically summarize the molecular mechanism underlying the influence of ncRNAs on the generation and development of drug resistance in pancreatic cancer and discuss the potential role of ncRNAs as prognostic markers and new therapeutic targets for pancreatic cancer.

lncRNA PART1 and MIR17HG as ΔNp63α direct targets regulate tumor progression of cervical squamous cell carcinoma

Cervical cancer (CC) remains one of the leading causes of mortality of female cancers worldwide, with more than 90% being cervical squamous cell carcinoma (CSCC). ΔNp63α is the predominant isoform expressed in cervical epithelial tissues and exerts its antitumor function in CSCC. In this study, we have identified 39 long noncoding RNAs as ΔNp63α targets in CSCC through RNA sequencing and chromatin immunoprecipitation sequencing, in which we further confirmed and focused on the two tumor‐related long noncoding RNAs, PART1 (lncPART1) and MIR17HG (lncMIR17HG). Experiments from stable overexpression/knockdown cell lines revealed that lncPART1 and lncMIR17HG regulated cell proliferation, migration, and invasion. In vivo experiments further showed that lncPART1 suppresses tumor growth in CSCC‐derived tumors. Examinations of clinical tissues indicated that the expression of lncPART1 was positively correlated with ΔNp63α expression, while lncMIR17HG was negatively correlated with ΔNp63α expression, suggesting that ΔNp63α plays a central role via regulating its direct targets in the progression of CSCC. These findings provide novel insights in targeted therapy of cervical cancers.

Hypoxia: a barricade to conquer the pancreatic cancer

Pancreatic cancer (PC) remains one of the most extremely lethal malignancies worldwide due to late diagnosis and early metastasis, with a 1-year overall survival rate of approximately 20%. The hypoxic microenvironment, induced by intratumoral hypoxia, promotes tumor invasion and progression, leading to chemotherapy or radiotherapy resistance and eventual mortality after treatment of PC. However, the role of the hypoxic microenvironment in PC is complicated and requires further investigation. In this article, we review recent advances regarding the regulation of malignant behaviors in PC, which provide insight into the potential of hypoxic microenvironment activation therapy for the therapeutic agents.

The Long Non-coding RNA LINC01705 Regulates the Development of Breast Cancer by Sponging miR-186-5p to Mediate TPR Expression as a Competitive Endogenous RNA

Long non-coding RNAs (lncRNAs) may be a regulatory factor of tumorigenesis. However, it is unclear what its biomechanisms are in breast cancer. In this study, different lncRNAs were detected in breast cancer through microarray analysis (GSE119233) and LINC01705 was selected for further study. qRT-PCR was then utilized for the detection of LINC01705 expression in breast cancer cells. A transwell assay, flow cytometry, 5-ethynyl-2'-deoxyuridine (EdU), a cell counting Kit-8 (CCK-8), and a wound-healing assay were performed to determine cell migration, invasion, apoptosis, and proliferation in breast cancer, respectively. For the identification of potential targets of LINC01705, dual-luciferase reporter gene and bioinformatics assays were conducted. Moreover, for the clarification of their interaction and roles in the regulation of the occurrence of breast cancer, Western blotting and RIP assays were conducted. Our findings revealed high LINC01705 expression in breast cancer tissues relative to adjacent non-cancerous tissues (n = 40, P < 0.001). Overexpression of LINC01705 notably enhanced cell migration and proliferation in breast cancer. In addition, LINC01705 positively regulated the translocated promoter region, nuclear basket protein (TPR) through competition with miR-186-5p. In conclusion, our results suggest that LINC01705 is implicated in the progression of breast cancer via competitively binding to miR-186-5p as a competing endogenous RNA (ceRNA), thereby regulating TPR expression.

Silencing of HIF-1α inhibited the expression of lncRNA NEAT1 to suppress development of hepatocellular carcinoma under hypoxia

BACKGROUND

We aimed to explore the relationship between hypoxia-inducible factors-1α (HIF-1α) and lncRNA nuclear-enriched abundant transcript 1 (NEAT1), and their functions on hepatocellular carcinoma (HCC) under hypoxia.

METHODS

HIF-1α and NEAT1 levels in HCC tissues and corresponding non-tumor tissues were determined by qRT-PCR, and the correlations of their levels in HCC tissues were analyzed by Pearson test. The relationship between overall survival and the two genes (HIF-1α and NEAT1) for HCC patients was detected by log-rank test. Clinicopathological features of NEAT1 in HCC patients were collected. HIF-1α and NEAT1 levels in HCC cells were measured by qRT-PCR and Western blot, and their relationship was determined by co-immunoprecipitation (Co-IP) assay. Cell viability, migration and invasion were detected by CCK-8, scratch wound healing and transwell assay, respectively. The interaction of NEAT1 with HIF-1α in tumor development was determined by xenograft tumor assays in nude mice.

RESULTS

NEAT1 and HIF-1α were highly expressed and showed a positive relationship in HCC tissues, and specifically, higher NEAT1 expression was positively associated with advanced TNM stage and metastasis in HCC patients. Up-regulated NEAT1 or HIF-1α in HCC patients had poorer prognosis. NEAT1 was induced by HIF-1α and suppressed by siHIF-1α. NEAT1 overexpression further promoted development of HCC under hypoxia while promoting cell viability, migration and invasion and suppressing apoptosis, and such effects were reversed by down-regulating HIF-1α. NEAT1 overexpression promoted tumor growth, which was reversed by down-regulating HIF-1α.

CONCLUSION

HIF-1α knockdown inhibits NEAT1 expression, which suppresses progression of HCC and improves its prognosis.

LINC00261 inhibits progression of pancreatic cancer by down-regulating miR-23a-3p

Long noncoding RNAs (lncRNAs) are usually dysregulated in the progression of pancreatic cancer. This research aims to explore the function and mechanism of LINC00261 in pancreatic cancer cell viability, invasion and apoptosis. Cancer Genome Atlas (TCGA) database was applied to analyze the association between survival probability of patients and level of LINC00261 or miR-23a-3p in pancreatic cancer. Quantitative reverse transcription polymerase chain reaction was conducted to analyze the levels of LINC00261 and miR-23a-3p. Cell viability, invasion and apoptosis of pancreatic cancer cells were determined via MTT, transwell invasion assay, and flow cytometry, respectively. The target relationship between LINC00261 and miR-23a-3p was determined via dual-luciferase reporter and RNA immunoprecipitation assays. Low level of LINC00261 indicated low survival probability of pancreatic cancer patients. LINC00261 level was decreased in pancreatic cancer cells than that in normal pancreatic ductal epithelial cells. Addition of LINC00261 restrained cell viability and invasion and facilitated apoptosis. miR-23a-3p was negatively correlated with LINC00261 level and high expression of miR-23a-3p indicated low survival probability. miR-23a-3p was targeted by LINC00261 and attenuated the influence of LINC00261 on pancreatic cancer cell viability, invasion and apoptosis. In conclusion, LINC00261 overexpression repressed cell viability and invasion and enhanced apoptosis by decreasing miR-23a-3p expression in pancreatic cancer cells, indicating a new target for the treatment of pancreatic cancer.

SPI1-induced upregulation of lncRNA SNHG6 promotes non-small cell lung cancer via miR-485-3p/VPS45 axis

More and more researches have proved that long noncoding RNAs (lncRNAs) are vital regulators and biological participants in human cancers [1-5]. SnoRNA host gene 6 (SNHG6) was found to have an effect on the early stage and tumorigenesis in many cancers [6-10]. However, the expression of SNHG6 and its role of in non-small cell lung cancer (NSCLC) still need to be investigated. This work aims to investigate the expression and its biological role in NSCLC. In our study, the expression of SNHG6 was abnormally high in NSCLC tissues and cells. The negative impact of SNHG6 expression on the overall survival of patients with NSCLC was analyzed with Kaplan Meier method. Functionally, loss of SNHG6 expression led to the inhibition on the growth, migration and invasion of NSCLC cells. Mechanistically, miR-485-3p was necessary for the regulatory relation between SNHG6 and VPS45. More importantly, SPI1 could promote the expression of SNHG6 via transcriptionally activation. In conclusion, we proved that SPI1/SNHG6/miR-485-3p/VPS45 axis exerted oncogenic role in the cellular process of NSCLC cells.

The long non-coding RNA PTTG3P promotes growth and metastasis of cervical cancer through PTTG1

The outgrowth and metastasis of cervical cancer (CC) contribute to its malignancy. Pituitary Tumor Transforming Gene 1 (PTTG1) is upregulated in many types of cancer, and enhances tumor cell growth and metastasis. However, the activation and regulation of PTTG1 in CC, especially by its pseudogene PTTG3P, have not been shown. Here, we detected significantly higher levels of PTTG1 and PTTG3P in the resected CC tissue, compared to the paired adjacent normal cervical tissue. Interestingly, the PTTG3P levels positively correlated with the PTTG1 levels. High PTTG3P levels were associated with poor patients’ survival. In vitro, PTTG1 were increased by PTTG3P overexpression, but was inhibited by PTTG3P depletion in CC cells. However, PTTG3P levels were not altered by modulation of PTTG1 in CC cells, suggesting that PTTG3P is upstream of PTTG1. Moreover, PTTG3P increased CC cell growth, likely through CCNB1-mediated increase in cell proliferation, rather than through decrease in cell apoptosis. Furthermore, PTTG3P increased CC cell invasiveness, likely through upregulation of SNAIL and downregulation of E-cadherin. Our work thus suggests that PTTG3P may promote growth and metastasis of CC through PTTG1.

Long noncoding RNAs and their link to cancer

The central dogma of molecular biology, developed from the study of simple organisms such as Escherichia coli, has up until recently been that RNA functions mainly as an information intermediate between a DNA sequence (gene), localized in the cell nucleus, serving as a template for the transcription of messenger RNAs, which in turn translocate into the cytoplasm and act as blueprints for the translation of their encoded proteins. There are a number of classes of non-protein coding RNAs (ncRNAs) which are essential for gene expression to function. The specific number of ncRNAs within the human genome is unknown. ncRNAs are classified on the basis of their size. Transcripts shorter than 200 nucleotides, referred to as ncRNAs, which group includes miRNAs, siRNAs, piRNAs, etc, have been extensively studied. Whilst transcripts with a length ranging between 200 nt up to 100 kilobases, referred to as lncRNAs, make up the second group, and are recently receiving growing concerns. LncRNAs play important roles in a variety of biological processes, regulating physiological functions of organisms, including epigenetic control of gene regulation, transcription and post-transcription, affecting various aspects of cellular homeostasis, including proliferation, survival, migration and genomic stability. LncRNAs are also capable of tuning gene expression and impact cellular signalling cascades, play crucial roles in promoter-specific gene regulation, and X-chromosome inactivation. Furthermore, it has been reported that lncRNAs interact with DNA, RNA, and/or protein molecules, and regulate chromatin organisation, transcriptional and post-transcriptional regulation. Consequently, they are differentially expressed in tumours, and they are directly linked to the transformation of healthy cells into tumour cells. As a result of their key functions in a wide range of biological processes, lncRNAs are becoming rising stars in biology and medicine, possessing potential active roles in various oncologic diseases, representing a gold mine of potential new biomarkers and drug targets.

Identification of key lncRNAs in the tumorigenesis of intraductal pancreatic mucinous neoplasm by coexpression network analysis

Intraductal papillary mucinous neoplasm (IPMN) is an intraepithelial precancerous lesion of pancreatic ductal adenocarcinoma (PDAC) that progresses from adenoma to carcinoma, and long noncoding RNAs (lncRNA) might be involved in the tumorigenesis. In this study, we obtained the expression profiles of more than 4000 lncRNAs by probe reannotation of a microarray dataset. As a correlation network‐based systems biology method, weighted gene coexpression network analysis (WGCNA) was used to find clusters of highly correlated lncRNAs in the tumorigenesis of IPMN, which covered four stepwise stages from normal main pancreatic duct to invasive IPMN. In the most relevant module (R² = −0.75 and P = 5E‐05), three hub lncRNAs were identified (HAND2‐AS1, CTD‐2033D15.2, and lncRNA‐TFG). HAND2‐AS1 and CTD‐2033D15.2 were negatively correlated with the tumorigenesis (P in one‐way ANOVA test = 1.45E‐07 and 1.39E‐0.5), while lncRNA‐TFG were positively correlated with the tumorigenesis (P = 3.99E‐08). The validation set reached consistent results (P = 2.66E‐03 in HAND2‐AS1, 1.47E‐04 in CTD‐2033D15.2 and 6.23E‐08 in lncRNA‐TFG). In functional enrichment analysis, the target genes of microRNAs targeting also these lncRNAs were overlapped in multiple biological processes, pathways and malignant diseases including pancreatic cancer. In survival analysis, patients with higher expression of HAND2‐AS1‐targeted and CTD‐2033D15.2‐targeted microRNAs showed a significantly poorer prognosis in PDAC, while high expression of lncRNA‐TFG‐targeted microRNAs demonstrated an obviously better prognosis (log‐rank P < .05). In conclusion, by coexpression network analysis of the lncRNA profiles, three key lncRNAs were identified in association with the tumorigenesis of IPMN, and those lncRNAs might act as early diagnostic biomarkers or therapeutic targets in pancreatic cancer.

The role of noncoding RNAs and sirtuins in cancer drug resistance

Cancer is a rising and major health issue around the world. The acquisition of resistance to chemotherapeutic drugs is a great obstacle for the effective treatment of nearly all cancers. Drug resistance is regulated by multiple factors and mechanisms including genetic mutations, abnormal expression of some cellular transporters such as multidrug resistance (MDR) transporters, changes in apoptotic pathways, cancer stem cells, tumor microenvironment, and noncoding RNAs (ncRNAs). Evidence clearly indicates a key role for sirtuins in several characteristics of cancer drug resistance. Recent studies demonstrated the crucial impact of some ncRNAs on sirtuins expression leading to modulation of chemotherapy resistance in cancers. In this review, we will focus on the current findings about the impacts of ncRNAs on the sirtuins pathway and their role in drug resistance of cancer.

Long Noncoding RNA FGD5-AS1 Acts as a Competing Endogenous RNA on microRNA-383 to Enhance the Malignant Characteristics of Esophageal Squamous Cell Carcinoma by Increasing SP1 Expression

Purpose

Previous studies have identified the important roles of a long noncoding RNA called FGD5 antisense RNA 1 (FGD5-AS1) in several types of human cancer. Nonetheless, to our knowledge, the expression and functions of FGD5-AS1 in esophageal squamous cell carcinoma (ESCC) have not been clarified. In this study, we aimed to determine the expression status of long noncoding RNA FGD5-AS1 in ESCC, determine its participation in ESCC progression, and uncover the underlying mechanisms.

Methods

ESCC tissue samples and paired normal adjacent tissues were collected to quantify FGD5-AS1 expression by reverse-transcription quantitative PCR. The effects of FGD5-AS1 on ESCC cell proliferation, apoptosis, migration, and invasion in vitro as well as tumor growth in vivo were studied using a Cell Counting Kit-8 assay, flow cytometry, Transwell migration and invasion assays, and an in vivo tumor xenograft experiment.

Results

FGD5-AS1 was found to be aberrantly upregulated in both ESCC tumors and cell lines compared to the control groups. Increased FGD5-AS1 expression manifested a close association with tumor size, TNM stage, and lymph node metastasis in patients with ESCC. Overall survival of patients with ESCC was shorter in the FGD5-AS1 high-expression group than in the FGD5-AS1 low-expression group. An FGD5-AS1 knockdown markedly attenuated ESCC cell proliferation, migration, and invasion and promoted apoptosis in vitro as well as slowed tumor growth in vivo. Mechanism investigation revealed that FGD5-AS1 can increase SP1 expression by sponging microRNA-383 (miR-383), thus functioning as a competing endogenous RNA. An miR-383 knockdown and recovery of SP1 expression attenuated the inhibition of the malignant characteristics of ESCC cells by the FGD5-AS1 knockdown.

Conclusion

Thus, FGD5-AS1 enhances the aggressive phenotype of ESCC cells in vitro and in vivo via the miR-383–SP1 axis, which may represent a novel target for ESCC therapy.

LncRNA XIST acts as a ceRNA sponging miR-185-5p to modulate pancreatic cancer cell proliferation via targeting CCND2

BACKGROUND

Long non-coding RNAs (lncRNAs) have been proved to be involved in the occurrence and progression of various tumors including pancreatic cancer (PC). Growing evidence shows that lncRNA X inactive-specific transcript (XIST) functions as an oncogene in multiple tumorigenesis. However, the underlying mechanism of lncRNA XIST in the progression of PC remains elusive.

METHODS

Expression levels of XIST and miR-185-5p both in PC tissues or PC cells were determined using real-time quantitative PCR (qRT-PCR). Gain and loss-of-function of XIST or miR-185-5p was performed for further exploration. Moreover, colony formation assay was performed to assess cell proliferation. Flow cytometry analysis was performed to measure cell cycle and apoptosis. Dual-luciferase reporter assay was conducted to verify the correlation between XIST, miR-185-5p and CCND2, respectively. Additionally, western blot analysis was conducted to determine the expression pattern of apoptosis-related proteins and cell cycle-associated proteins.

RESULTS

Herein, we found that XIST expression was up-regulated while miR-185-5p was down-regulated both in PC tissues and cell lines, compared with that of controls. Moreover, there was a negative correlation between XIST and miR-185-5p. Following that, functional experiments displayed that knockdown of XIST or overexpression of miR-185-5p inhibited cell proliferation, induced cell cycle arrest and promoted apoptosis in PC cells. Furthermore, mechanistic experiments displayed that XIST could negatively regulate miR-185-5p via direct binding. In addition, CCND2 was shown to be a downstream target of miR-185-5p. Importantly, overexpression or knockdown of XIST significantly increased or decreased the expression of CCND2, while these effects were reversed by miR-185-5p.

CONCLUSIONS

Taken together, our study demonstrated that lncRNA XIST functions as an oncogene and exerts its regulation via miR-185-5p/CCND2 axis, promoting proliferation and inhibiting apoptosis in PC.

The multifaceted roles of long noncoding RNAs in pancreatic cancer: an update on what we know

Pancreatic cancer (PC) is one of the leading causes of cancer-related deaths worldwide. Due to the shortage of effective biomarkers for predicting survival and diagnosing PC, the underlying mechanism is still intensively investigated but poorly understood. Long noncoding RNAs (lncRNAs) provide biological functional diversity and complexity in protein regulatory networks. Scientific studies have revealed the emerging functions and regulatory roles of lncRNAs in PC behaviors. It is worth noting that some in-depth studies have revealed that lncRNAs are significantly associated with the initiation and progression of PC. As lncRNAs have good properties for both diagnostic and prognostic prediction due to their translation potential, we herein address the current understanding of the multifaceted roles of lncRNAs as regulators in the molecular mechanism of PC. We also discuss the possibility of using lncRNAs as survival biomarkers and their contributions to the development of targeted therapies based on the literature. The present review, based on what we know about current research findings, may help us better understand the roles of lncRNAs in PC.

Long noncoding RNA LINC01278 favors the progression of osteosarcoma via modulating miR-133a-3p/PTHR1 signaling

As one of the most aggressive malignancies, osteosarcoma has high risks of death. Although long noncoding RNAs (lncRNAs) may promote the osteosarcoma progression as verified, the potential molecular mechanism of lncRNAs in osteosarcoma remains unknown. Herein, we analyzed lncRNA microarray of osteosarcoma and selected LINC01278 as the study object. Then, we found that the expression of LINC01278 tested by quantitative reverse-transcription polymerase chain reaction was enhanced in tumor tissues compared with the para-carcinoma tissues and related to clinical stage, distant metastasis in osteosarcoma. In addition, the clinical outcomes were poor in osteosarcoma patients with high LINC01278 level. Moreover, LINC01278 promoted proliferation and restrained apoptosis in osteosarcoma cells. Afterward, mechanistic studies turned out that LINC01278 was a competing endogenous RNA of parathyroid hormone type 1 receptor (PTHR1) in osteosarcoma by sponging miR-133a-3p, which was considered as a tumor inhibitor in osteosarcoma. Furthermore, PTHR1 downregulation restored the impacts of inhibited miR-133a-3p on the processes in osteosarcoma cells. Our findings clarified that the carcinogenic effect of LINC01278 in osteosarcoma was mediated through miR-133a-3p/PTHR1 signaling, creating a novel insight into good targets for the therapy and prognosis of osteosarcoma.

Identify potential clinical significance of long noncoding RNA forkhead box P4 antisense RNA 1 in patients with early stage pancreatic ductal adenocarcinoma

Previous studies have shown that forkhead box P4 antisense RNA 1 (FOXP4‐AS1) is dysregulated in tumor tissues and can serve as a prognostic indicator for multiple cancers. However, the clinical significance of FOXP4‐AS1 in pancreatic ductal adenocarcinoma (PDAC) remains unclear. The goal of this study is to recognize the possible clinical significance of long noncoding RNA FOXP4‐AS1 in patients with early stage PDAC. A total of 112 patients from The Cancer Genome Atlas (TCGA) PDAC cohort, receiving RNA sequencing, were involved in the study. Survival analysis, functional mechanism, and potential small molecule drugs of target therapy of FOXP4‐AS1 were performed in this study. Survival analysis in TCGA PDAC cohort suggested that patients with high FOXP4‐AS1 expression had significantly augmented possibility of death than in PDAC patients with lower FOXP4‐AS1 expression (adjusted P = .008; adjusted HR = 2.143, 95% CI = 1.221‐3.760). In this study, a genome‐wide RNA sequencing dataset was used to identify 927 genes co‐expressing with FOXP4‐AS1 in PDAC tumor tissues. A total of 676 differentially expressed genes were identified between different FOXP4‐AS1 expression groups. Functional enrichment analysis of these genes and gene set enrichment analysis for PDAC genome‐wide RNA sequencing dataset was done. We have found that FOXP4‐AS1 may function in PDAC by participating in biological processes and pathways including oxidative phosphorylation, tricarboxylic acid cycle, classical tumor‐related pathways such as NF‐kappaB as well as Janus kinase/signal transducers in addition to activators of transcription, cell proliferation, and adhesion. In addition, we also screened two potential targeted therapeutic small molecule drugs (dimenhydrinate and metanephrine) for FOXP4‐AS1 in PDAC. In conclusion, our present study demonstrated that higher expression of FOXP4‐AS1 in PDAC tumor tissues were related with an inferior medical outcome. Through multiple genome‐wide approaches, we identified the potential molecular mechanisms of FOXP4‐AS1 in PDAC and two targeted therapeutic drugs for it.

Long noncoding RNA 00976 promotes pancreatic cancer progression through OTUD7B by sponging miR-137 involving EGFR/MAPK pathway

BACKGROUND

Accumulation evidence indicates the vital role of long non-coding RNAs (lncRNAs) in tumorigenesis and the progression of malignant tumors, including pancreatic cancer (PC). However, the role and the molecular mechanism of long non-coding RNA 00976 is unclear in pancreatic cancer.

METHODS

In situ hybridization (ISH) and qRT-PCR was performed to investigate the association between linc00976 expression and the clinicopathological characteristics and prognosis of patients with PC. Subsequently, linc00976 over-expression vector and shRNAs were transfected into PC cells to up-regulate or down-regulate linc00976 expression. Loss- and gain-of function assays were performed to investigate the role of linc00976 in proliferation and metastasis in vitro and vivo. ITRAQ, bioinformatic analysis and rescue assay were used to illustrate the ceRNA mechanism network of linc00976/miR-137/OTUD7B and its downstream EGFR/MAPK signaling pathway.

RESULTS

linc00976 expression was overexpressed in PC tissues and cell lines and was positively associated with poorer survival in patients with PC. Function studies revealed that linc00976 knockdown significantly suppressed cell proliferation, migration and invasion in vivo and in vitro, whereas its overexpression reversed these effects. Based on Itraq results and online database prediction, Ovarian tumor proteases OTUD7B was found as a downstream gene of linc00976, which deubiquitinated EGFR mediates MAPK signaling activation. Furthermore, Bioinformatics analysis and luciferase assays and rescue experiments revealed that linc00976/miR137/OTUD7B established the ceRNA network modulating PC cell proliferation and tumor growth.

CONCLUSION

The present study demonstrates that linc00976 enhances the proliferation and invasion ability of PC cells by upregulating OTUD7B expression, which was a target of miR-137. Ultimately, OTUD7B mediates EGFR and MAPK signaling pathway, suggesting that linc00976/miR-137/OTUD7B/EGFR axis may act as a potential biomarker and therapeutic target for PC.