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

Association of Genetic Polymorphisms in Long Noncoding RNA HOTTIP with Risk of Idiopathic Recurrent Spontaneous Abortion

The clustered homeobox gene family known as the Hox family plays a fundamental role in the morphogenesis of the vertebrate's embryo. A long noncoding RNA (lncRNA), known as HOTTIP (HOXA transcript at the distal tip), has been functionally characterized and contributed to the pathogenesis of various conditions. The current case-control study was undertaken to examine the gene frequencies and shared alleles of the HOTTIP  gene in Iranian participants with or without idiopathic recurrent spontaneous abortion (RSA). Both ARMS-PCR reaction and RFLP-PCR techniques were employed to detect three HOTTIP polymorphisms (rs2023843C/T, rs78248039A/T, and rs1859168C/A) in a DNA sample of 161 women with RSA and 177 healthy women. We found that the TT genotype of the HOTTIP rs2023843 C/T polymorphism was associated with a lower risk for idiopathic RSA. In contrast, the TT genotype of the HOTTIP rs78248039 A/T polymorphism was correlated with an enhanced risk of RSA. The presence of the A-allele for HOTTIP rs1859168 C/A polymorphism was associated with an increased risk for idiopathic RSA. Haplotype analysis showed that the T/T/A, C/T/A, T/T/C, and T/A/A haplotypes of rs2023843/rs78248039/rs1859168 enhanced RSA susceptibility. Computational analysis predicted that this lncRNA might act as a potential sponge for some microRNAs; therefore, affecting the expression of genes being targeted by them. In addition, both rs2023843 and rs1859168 variants could alter the local secondary structure of HOTTIP. Our results showed that HOTTIP rs2023843C/T, rs78248039A/T, and rs1859168C/A polymorphisms may confer genetic susceptibility to idiopathic RSA in an Iranian population.

The Expression Analysis of Long Non-coding RNAs Related to Wnt/β-Catenin Signaling in Pancreatic Cancer Patients

Background The oncogenic Wnt/β-catenin signaling plays a critical role in carcinogenesis, prognosis, and resistance to therapy. Pancreatic cancer (PC) has high mortality because of its poor prognosis. Several studies have suggested that lncRNAs are directly involved in the development and progression of PC as well as in Wnt/β-catenin signaling. In this study, we investigated and compared the expression of Wnt/β-catenin signaling-related ZFAS1 and HCG11 lncRNAs, and their targets, CTNNB1 and IGF2BP1 genes in the blood of patients with PC and healthy individuals. A total of 47 PC patients and 50 healthy individuals participated in this study. RNA was extracted from the peripheral blood samples of participants, and cDNA was synthesized. The expression level of the selected genes was quantified by real-time PCR. The expression of HCG11 lncRNA and CTNNB1 genes in patients with PC was significantly upregulated compared to healthy individuals, and the expression of the ZFAS1 lncRNA was significantly downregulated. According to the analysis of the ROC curve, the diagnostic powers of ZFAS1 and CTNNB1 in PC were 0.67 and 0.69, respectively. Altogether, the present study suggests a role for ZFAS1 and HCG11 lncRNAs and CTNNB1 and IGF2BP1 in the pathogenesis of pancreatic cancer. Moreover, the peripheral expression of these lncRNAs may be useful as potential biomarkers for PC.

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.

UCA1 executes an oncogenic role in pancreatic cancer by regulating miR-582-5p/BRCC3

Background

As a fatal disease, the mechanism of pancreatic cancer is unclear. Urothelial carcinoma antigen 1(UCA1), a long noncoding RNA (lncRNA) that was first reported in bladder cancer, acts as an oncogene. However, the regulatory role and mechanism of UCA1 in pancreatic cancer remain unknown. This study aims to investigate the expression level and prognostic value of UCA1 in pancreatic cancer tissues, the effects and mechanism of UCA1 in regulating cell proliferation, apoptosis and metastasis.

Methods

UCA1 expression levels in tissues were detected by in situ hybridization (ISH) and the prognostic value was evaluated by univariate and multivariate survival analysis. For in vitro experiments, proliferation was evaluated by a cell count kit assay, Edu experiments, and a clone formation assay. Apoptosis was evaluated by fluorescence-activated cell sorting flow-cytometry. Cell migration and invasion capacities were detected by wound healing and transwell assays. Western blots were performed to detect apoptotic associated molecules and epithelial-mesenchymal transition (EMT) markers. For the in vivo experiment, subcutaneous transplantation models of pancreatic cancer in nude mice were established to observe the tumor growth. The regulatory mechanism of UCA1 was explored by proteomics, bioinformatic analysis, luciferase reporter assays, and rescue experiments.

Results

ISH staining revealed that UCA1 levels between cancer tissues (n=94) and tumor-adjacent tissues (n=73) did not show significant differences. Survival analysis indicated that high expression of UCA1 was an unfavorable prognosis factor for pancreatic cancer. Downregulation of UCA1 by siRNA significantly inhibited cell proliferation, decreased the capacities of cell migration and invasion, induced cell apoptosis, and inhibited EMT. Furthermore, we demonstrated that UCA1 positively regulated the expression of BRCC3 by inhibiting miR-582-5p. Rescue experiments indicated that either inhibiting the expression of miR-582-5p or enhancing expression of BRCC3 could partly attenuate the antitumor effects of downregulation of UCA1.

Conclusion

UCA1 acted as an oncogene in pancreatic cancer by partly regulating miR-582-5p/BRCC3, which could be a new therapeutic target for pancreatic cancer.

Role of long non-coding RNAs in pancreatic cancer pathogenesis and treatment resistance- A review

Pancreatic cancer (PC) is one of the deadliest cancers associated with poor prognosis. The lack of reliable means of early cancer detection contributes to this disease's dismal prognosis. Long non-coding RNAs (LncRNAs) are protein-free RNAs produced by genome transcription; they play critical roles in gene expression regulation, epigenetic modification, cell proliferation, differentiation, and reproduction. Recent research has shown that lncRNAs play important regulatory roles in PC behaviors, in addition to their recently found functions. Several in-depth investigations have shown that lncRNAs are strongly linked to PC development and progression. Here, we discuss how lncRNAs, which are often overlooked, play many roles as regulators in the molecular mechanism underlying PC. This review also discusses the involved LncRNAs in PC pathogenesis and treatment resistance.

Integration of mRNA and protein expression data for the identification of potential biomarkers associated with pancreatic ductal adenocarcinoma

Pancreatic ductal adenocarcinoma (PDAC) is one of the most death-dealing tumors, with a tremendously poor prognosis. Here, we, through interrogation of mRNA and protein data combined with a system biology approach, identified several key genes, functional processes, and pathways that can have critical roles in PDAC. We detected an interesting module related to the clinical traits that enriched in the ribosome, hematopoietic cell lineage, and cell adhesion molecules-related pathways. We also identified several hub genes in important modules that are associated with immune system processes. The results also indicated some lncRNAs, such as FAM30A, and MIR223HG with essential functions that are involved in PDAC. Additionally, five genes, including CD53, ITGAL, WDFY4, TLX1, and LMAN1L were screened by survival analysis and can be considered as candidate biomarkers or therapeutic targets. According to our strategy, the findings of this study may provide a better understanding of the molecular mechanisms and suggest potential prognostic and therapeutic targets for PDAC.

Implications of a Neuronal Receptor Family, Metabotropic Glutamate Receptors, in Cancer Development and Progression

Cancer is the second leading cause of death, and incidences are increasing globally. Simply defined, cancer is the uncontrolled proliferation of a cell, and depending on the tissue of origin, the cancer etiology, biology, progression, prognosis, and treatment will differ. Carcinogenesis and its progression are associated with genetic factors that can either be inherited and/or acquired and are classified as an oncogene or tumor suppressor. Many of these genetic factors converge on common signaling pathway(s), such as the MAPK and PI3K/AKT pathways. In this review, we will focus on the metabotropic glutamate receptor (mGluR) family, an upstream protein that transmits extracellular signals into the cell and has been shown to regulate many aspects of tumor development and progression. We explore the involvement of members of this receptor family in various cancers that include breast cancer, colorectal cancer, glioma, kidney cancer, melanoma, oral cancer, osteosarcoma, pancreatic cancer, prostate cancer, and T-cell cancers. Intriguingly, depending on the member, mGluRs can either be classified as oncogenes or tumor suppressors, although in general most act as an oncogene. The extensive work done to elucidate the role of mGluRs in various cancers suggests that it might be a viable strategy to therapeutically target glutamatergic signaling.

Emerging role of lncRNA ELDR in development and cancer

Whole-genome sequencing and transcriptome analysis revealed more than 90% of the human genome transcribes noncoding RNAs including lncRNAs. From the beginning of the 21st century, lncRNAs have gained widespread attention as a new layer of regulation in biological processes. lncRNAs are > 200 nucleotides in size, transcribed by RNA polymerase II, and share many similarities with mRNAs. lncRNA interacts with DNA, RNA, protein, and miRNAs, thereby regulating many biological processes. In this review, we have focused mainly on LINC01156 [also known as the EGFR long non-coding downstream RNA (ELDR) or Fabl] and its biological importance. ELDR is a newly identified lncRNA and first reported in a mouse model, but it has a human homolog. The human ELDR gene is closely localized downstream of epidermal growth factor receptor (EGFR) gene at chromosome 7 on the opposite strand. ELDR is highly expressed in neuronal stem cells and associated with neuronal differentiation and mouse brain development. ELDR is upregulated in head and neck cancer, suggesting its role as an oncogene and its importance in prognosis and therapy. Publicly available RNA-seq data further support its oncogenic potential in different cancers. Here, we summarize all the aspects of ELDR in development and cancer, highlighting its future perspectives in the context of mechanism.

Repeat expression is linked to patient survival and exhibits single nucleotide variation in pancreatic cancer revealing LTR70:r.879A>G

Despite an overwhelming number of cancer literature reporting the links between patient survival and the expression levels of genes or mutations/single nucleotide variations (SNVs) on them, there is only limited information on repeat elements, which make at least half the human genome. Here, we analysed RNA-seq data obtained from primary pancreatic cancer tissues of 51 patients and revealed that two transposons, HERVI-int and X6A_LINE, showed an upregulation trend in the patients who lived shorter, along with 56 other potential repeats which were linked to survival. We also detected expressed single nucleotide variations (SNVs) on repeats, among which LTR70:r.879A>G stands out with the effect of its presence on this particular repeat's expression levels and a significant link to overall patient survival. Interestingly, the expression of LTR70:r.879A>G correlated with different cancer genes in comparison to its reference version highlighting the involvement of BRAF and Fumerate Hydratase with this expressed SNV. This is one of the first studies revealing possible links between repeat expression and survival in cancer and it warrants further research in this avenue.

Hypoxia-induced long noncoding RNA NR2F1-AS1 maintains pancreatic cancer proliferation, migration, and invasion by activating the NR2F1/AKT/mTOR axis

Accumulating evidence has demonstrated the essential role of long noncoding RNAs (lncRNAs) in various types of human cancer, including pancreatic cancer (PC). However, the functions and regulatory mechanisms of nuclear receptor subfamily 2 group F member 1 antisense RNA 1 (NR2F1-AS1) that are responsible for its role in the malignant progression of PC cells remains to be investigated. In this study, the biological effects of NR2F1-AS1 and NR2F1 in PC were investigated by in vitro and in vivo experiments. The mechanisms of NR2F1-AS1 were monitored by bioinformatic predictive analysis and confirmatory experiments. Our results indicated that NR2F1-AS1 was overexpressed and positively correlated with poor survival in PC. Depletion of NR2F1-AS1 restrained PC cell proliferation, migration, invasion, and suppressed xenograft tumor growth and metastasis in vitro and in vivo. Mechanistic experiments suggested that NR2F1-AS1 positively regulated the neighboring NR2F1 gene, which subsequently activated AKT/mTOR signaling, resulting in the upregulation of hypoxia-inducible factor-1α (HIF-1α). Further investigations elucidated that NR2F1-AS1 expression was transcriptionally regulated by HIF-1α under hypoxia. These findings demonstrated that hypoxia-induced NR2F1-AS1 expression directly increased NR2F1 levels to promote PC cell proliferation, migration, and invasion by activating AKT/mTOR signaling. Together, these findings suggest that NR2F1-AS1 could be a prospective therapeutic target for PC.

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.

Pancreatic stellate cells - rising stars in pancreatic pathologies

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

Autophagy and gastrointestinal cancers: the behind the scenes role of long non-coding RNAs in initiation, progression, and treatment resistance

Gastrointestinal (GI) cancers comprise a heterogeneous group of complex disorders that affect different organs, including esophagus, stomach, gallbladder, liver, biliary tract, pancreas, small intestine, colon, rectum, and anus. Recently, an explosion in nucleic acid-based technologies has led to the discovery of long non-coding RNAs (lncRNAs) that have been found to possess unique regulatory functions. This class of RNAs is >200 nucleotides in length, and is characterized by their lack of protein coding. LncRNAs exert regulatory effects in GI cancer development by affecting different functions such as the proliferation and metastasis of cancer cells, apoptosis, glycolysis and angiogenesis. Over the past few decades, considerable evidence has revealed the important role of autophagy in both GI cancer progression and suppression. In addition, recent studies have confirmed a significant correlation between lncRNAs and the regulation of autophagy. In this review, we summarize how lncRNAs play a behind the scenes role in the pathogenesis of GI cancers through regulation of autophagy.

Epithelial to Mesenchymal Transition: Key Regulator of Pancreatic Ductal Adenocarcinoma Progression and Chemoresistance

Simple Summary

Pancreatic ductal adenocarcinoma’s (PDAC) dismal prognosis is associated with its aggressive biological behavior and resistance to chemotherapy. Epithelial to mesenchymal transition (EMT) has been recognized as a key driver of PDAC progression and development of drug resistance. EMT is a transient and reversible process leading to transdifferentiation of epithelial cells into a more mesenchymal phenotype. It is regulated by multiple signaling pathways that control the activity of a transcription factors network. Activation of EMT in pre-invasive stages of PDAC has been accused for early dissemination. Furthermore, it contributes to the development of intratumoral heterogeneity and drug resistance. This review summarizes the available data regarding signaling networks regulating EMT and describes the integral role of EMT in different aspects of PDAC pathogenesis.

Abstract

Pancreatic ductal adenocarcinoma (PDAC) is one of the deadliest malignancies, characterized by aggressive biological behavior and a lack of response to currently available chemotherapy. Emerging evidence has identified epithelial to mesenchymal transition (EMT) as a key driver of PDAC progression and a central regulator in the development of drug resistance. EMT is a reversible transdifferentiation process controlled by complex interactions between multiple signaling pathways such as TGFb, Wnt, and Notch, which converge to a network of specific transcription factors. Activation of EMT transcriptional reprogramming converts cancer cells of epithelial differentiation into a more mesenchymal phenotypic state. EMT occurrence in pre-invasive pancreatic lesions has been implicated in early PDAC dissemination. Moreover, cancer cell phenotypic plasticity driven by EMT contributes to intratumoral heterogeneity and drug tolerance and is mechanistically associated with the emergence of cells exhibiting cancer stem cells (CSCs) phenotype. In this review we summarize the available data on the signaling cascades regulating EMT and the molecular isnteractions between pancreatic cancer and stromal cells that activate them. In addition, we provide a link between EMT, tumor progression, and chemoresistance in PDAC.

NR2F1-AS1 Promotes Pancreatic Ductal Adenocarcinoma Progression Through Competing Endogenous RNA Regulatory Network Constructed by Sponging miRNA-146a-5p/miRNA-877-5p

The role of NR2F1-AS1 in pancreatic ductal adenocarcinoma (PDAC) remains unknown. Therefore, we aimed to investigate the biological mechanism of NR2F1-AS1 in PDAC. The expression of NR2F1-AS1 was measured by using microarray data and real-time PCR. The effects of NR2F1-AS1 knockdown on proliferation, cell cycle progression, invasion in vitro and tumorigenesis in vivo were investigated. The mechanism of competitive endogenous RNAs was determined from bioinformatics analyses and validated by a dual-luciferase reporter gene assay. Potential target mRNAs from TargetScan 7.2 were selected for subsequent bioinformatics analysis. Key target mRNAs were further identified by screening hub genes and coexpressed protein-coding genes (CEGs) of NR2F1-AS1. NR2F1-AS1 was highly expressed in PDAC, and the overexpression of NR2F1-AS1 was associated with overall survival and disease-free survival. The knockdown of NR2F1-AS1 impaired PDAC cell proliferation, migration, invasion and tumorigenesis. NR2F1-AS1 competitively sponged miR-146a-5p and miR-877-5p, and low expression of the two miRNAs was associated with a poor prognosis. An integrative expression and survival analysis of the hub genes and CEGs demonstrated that the NR2F1-AS1–miR-146a-5p/miR-877-5p–GALNT10/ZNF532/SLC39A1/PGK1/LCO3A1/NRP2/LPCAT2/PSMA4 and CLTC ceRNA networks were linked to the prognosis of PDAC. In conclusion, NR2F1-AS1 overexpression was significantly associated with poor prognosis. NR2F1-AS1 functions as an endogenous RNA to construct a novel ceRNA network by competitively binding to miR-146a-5p/miR-877-5p, which may contribute to PDAC pathogenesis and could represent a promising diagnostic biomarker or potential novel therapeutic target in PDAC.

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.

LINC00671 suppresses cell proliferation and metastasis in pancreatic cancer by inhibiting AKT and ERK signaling pathway

Long noncoding RNAs (lncRNAs) represent an emerging field of tumor biology, playing essential roles in cancer cell proliferation, invasion, and metastasis. However, the overall functional and clinical significance of most lncRNAs in pancreatic cancer is not thoroughly understood. Here, we described most of the lncRNAs with aberrant expression patterns in pancreatic cancer as detected by microarray. Quantitative real-time polymerase chain reaction further verified that the expression of LINC00671 was decreased in pancreatic cancer cell lines and patient samples. Furthermore, lower LINC00671 expression was associated with reduced tumor differentiation, aggressiveness, and poor prognosis. Functionally, LINC00671 overexpression inhibited pancreatic cancer cell proliferation, invasion, and migration in vitro, and reduced tumor growth in vivo. LINC00671 is mainly located in the cytoplasm. RNA sequencing and bioinformatics analyses indicated that LINC00671 binds to multiple miRNAs and therefore could be involved in multiple tumor-associated pathways, such as the AMPK signaling pathway and PI3K-Akt signaling pathway. Western blotting and immunohistochemistry further confirmed that LINC00671 overexpression suppressed the AKT, ERK, and epithelial-mesenchymal transition pathways. Overall, these results indicated that LINC00671 acts as a novel tumor suppressor in pancreatic cancer. Our findings may provide a new potential target for the treatment of pancreatic cancer.

The Role of LncRNAs in Translation

Long non-coding RNAs (lncRNAs), a group of non-protein coding RNAs with lengths of more than 200 nucleotides, exert their effects by binding to DNA, mRNA, microRNA, and proteins and regulate gene expression at the transcriptional, post-transcriptional, translational, and post-translational levels. Depending on cellular location, lncRNAs are involved in a wide range of cellular functions, including chromatin modification, transcriptional activation, transcriptional interference, scaffolding and regulation of translational machinery. This review highlights recent studies on lncRNAs in the regulation of protein translation by modulating the translational factors (i.e, eIF4E, eIF4G, eIF4A, 4E-BP1, eEF5A) and signaling pathways involved in this process as wells as their potential roles as tumor suppressors or tumor promoters.

LncRNAs in cancer: Regulatory and therapeutic implications

Long noncoding RNAs (lncRNAs) comprise a class of RNAs that do not code for proteins but are critical in regulating diverse cellular processes and maintaining cell function. In doing so, they have, in recent years, added a potentially new and significant layer of biological regulation. These are more than 200 nucleotides in length and are implicated in a range of diseases and therefore have emerged as potential tools for possible therapeutic intervention. For a disease as complex as cancer, emerging technologies suggest the presence of mutations on genomic loci that do not encode proteins, but give rise to lncRNAs. Aberrant signatures of lncRNAs are now a consistent feature of almost all types of cancers and their associated complications. Analysis and characterisation of functional pathways that lncRNAs are involved with suggest that lncRNAs interact with the chromatin, the protein or with the RNA to demonstrate their cellular effects to modulate proliferation, migration, differentiation, apoptosis and cell death. This review summarizes the current knowledge of lncRNAs, their implications in diverse types of cancer and their possible therapeutic utility.

Long noncoding RNA SNHG4 promotes renal cell carcinoma tumorigenesis and invasion by acting as ceRNA to sponge miR-204-5p and upregulate RUNX2

Background

Long noncoding RNAs (lncRNAs) are involved in the tumorigenesis and progression of human cancers, including renal cell carcinoma (RCC). Small nucleolar RNA host gene 4 (SNHG4) is reported to play an essential role in tumor growth and progression. However, the molecular mechanisms and function of SNHG4 in RCC remain undocumented.

Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was performed to examine expression levels of SNHG4 in RCC tissue samples and cell lines. Cell counting kit-8, western blotting, activities of caspase-3, -8, and -9, wound-healing, and transwell invasion assays were performed to explore cell proliferation, apoptosis, migration, and invasion. The interaction among SNHG4, miR-204-5p, and RUNX2 was verified by bioinformatic analysis, a luciferase gene report, qRT-PCR, western blot analysis, and RNA immunoprecipitation assays. Xenograft mouse models were carried out to examine the role of SNHG4 in RCC in vivo.

Results

SNHG4 was highly expressed in RCC tissue samples and cell lines, and its upregulation was significantly involved in node involvement, distant metastasis, and reduced overall and relapse-free survival of patients with RCC. SNHG4 acted as an oncogenic lncRNA with promoted RCC cell proliferation, migration, invasion, and inhibited apoptosis. SNHG4 boosted tumor growth in xenograft mouse models. Mechanistically, SNHG4 functioned as a competing endogenous RNA (ceRNA) for sponging miR-204-5p, leading to the upregulation of its target RUNX2 to promote RCC cell proliferation and invasion.

Conclusion

SNHG4 and miR-204-5p might be indicated in RCC progression via RUNX2, suggesting the potential use of SNHG4/miR-204-5p/RUNX2 axis in RCC treatment.

The implication of long non-coding RNAs in the diagnosis, pathogenesis and drug resistance of pancreatic ductal adenocarcinoma and their possible therapeutic potential

Pancreatic ductal adenocarcinoma (PDAC) is one of the lethal malignancies with the lowest median and overall survival rate among all human malignancies. The major problems with the PDAC are the late diagnosis, metastasis, and acquired resistance to chemotherapeutic agents in the clinic. Over the last decade, the long non-coding RNAs (lncRNAs) have been discovered and occupies a significantly large proportion of the human genome. Recent studies have proved that lncRNAs can play a crucial role in the majority of key cellular processes involved in the maintenance of cellular homeostasis by regulating various molecular mechanisms. The deregulation of lncRNAs has been associated with various chronic diseases including human malignancies. Several lncRNAs have tumor-specific expression making them an ideal and excellent target for designing the novel therapeutic strategies against human malignancies. We have discussed how lncRNA expression can be used for the diagnosis and prognosis of PDAC. The current review discusses the potential role and molecular mechanism of lncRNA in regulating the prominent hallmarks of cancer including abnormal growth, survival, metastasis, and drug-resistance in PDAC. Importantly, we also highlight the possible application of various therapeutic strategies including small interfering RNA, CRISPR-Cas9, antisense oligonucleotides, locked nucleic acid Gapmers, small molecules, aptamers, lncRNA promoter to target the lncRNA as a novel and viable options for treatment of PDAC.