LncRNA-UCA1 enhances cell proliferation and 5-fluorouracil resistance in colorectal cancer by inhibiting miR-204-5p. Sci Rep. 2016;6:23892. [PMID: 27046651 PMCID: PMC4820696 DOI: 10.1038/srep23892]

Cationic vesicles for efficient shRNA transfection in the MCF-7 breast cancer cell line

INTRODUCTION

Novel and safe delivery solutions for RNAi therapeutics are essential to obtain the full potential of cancer gene therapy.

METHODS

In this study, cationic vesicular nanocarrier was applied for delivering lnc urothelial carcinoma-associated 1 (lnc UCA1) shRNA expression vector to MCF-7 cells. The physicochemical characteristics, cytotoxicity, and transfection efficiency of cationic vesicles prepared from various molar ratios of amphiphilic surfactant Tween 80 (T), squalene (S), cationic charge lipid didodecyldimethylammonium bromide, and polyethylenimine were investigated. The particle sizes of the vesicles in the nanosize range were determined by dynamic light scattering and transmission electron microscopy.

RESULTS

Gel protection assay with agarose gel electrophoresis showed cationic vesicles can protect the shRNA plasmid from DNase 1 enzyme. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H tetrazolium, inner salt result showed no significant cytotoxicity was caused in MCF-7 cancer cell line by (T:S):polyethylenimine cationic vesicles. 3-(4,5-Dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H tetrazolium, inner salt assay, fluorescence microscope images, and flow cytometry analyses confirmed that (T:S)1,040 μM with 4.3 μg/mL of PEI vesicles provided effective transfection without significant cytotoxicity. Furthermore, we found efficient UCA1 shRNA transfection and significant (P<0.05) cell cycle arrest and apoptosis in MCF-7 cancer cells.

CONCLUSION

The novel nonviral vesicular nanocarrier, (T:S)1,040 μM with 4.3 μg/mL of PEI, might be safe and efficient for cancer gene therapy and can be used in further in vitro and in vivo studies.

Knockdown of long noncoding RNA urothelial carcinoma associated 1 inhibits colorectal cancer cell proliferation and promotes apoptosis via modulating autophagy

Long noncoding RNA urothelial carcinoma associated 1 (UCA1) has been implicated in the growth and metastasis of colorectal cancer (CRC), and autophagy contributes to tumorigenesis and cancer cell survival. However, the regulatory role of UCA1 in CRC cell viability by modulating autophagy remains unclear. In the present study, a significant positive correlation was observed between UCA1 and microtubule-associated protein 1 light chain 3 (LC3) levels, and the elevated UCA1 was negatively correlated with the PKB/protein kinase B (AKT)/mammalian target of rapamycin (mTOR) signaling pathway in 293T cells. Downregulation of UCA1 inhibited autophagy activation and cell proliferation, whereas the apoptosis was increased and the cell cycle was arrested in G2 stage. The next results showed that UCA1 was markedly upregulated in Caco-2 cells. Knockdown of UCA1 significantly decreased the LC3-II and autophagy-related gene 5 (ATG5) protein levels and resulted in an increase in p62 expression. Conversely, the autophagy activator rapamycin (RAPA) reversed the effects. Furthermore, downregulated UCA1 decreased Caco-2 cells population in the G1 phase and increased the cells number in G2 phage. The cell proliferation was inhibited, and apoptosis rate was promoted. More important, RAPA could also abrogate the changes induced by knockdown of UCA1. Collectively, these data demonstrated that downregulated UCA1 induced autophagy inhibition, resulting in suppressing cell proliferation and promoting apoptosis, which suggested that UCA1 might serve as a potential new oncogene to regulate CRC cells viability by modulating autophagy.

Long non-coding RNA-dependent mechanism to regulate heme biosynthesis and erythrocyte development

In addition to serving as a prosthetic group for enzymes and a hemoglobin structural component, heme is a crucial homeostatic regulator of erythroid cell development and function. While lncRNAs modulate diverse physiological and pathological cellular processes, their involvement in heme-dependent mechanisms is largely unexplored. In this study, we elucidated a lncRNA (UCA1)-mediated mechanism that regulates heme metabolism in human erythroid cells. We discovered that UCA1 expression is dynamically regulated during human erythroid maturation, with a maximal expression in proerythroblasts. UCA1 depletion predominantly impairs heme biosynthesis and arrests erythroid differentiation at the proerythroblast stage. Mechanistic analysis revealed that UCA1 physically interacts with the RNA-binding protein PTBP1, and UCA1 functions as an RNA scaffold to recruit PTBP1 to ALAS2 mRNA, which stabilizes ALAS2 mRNA. These results define a lncRNA-mediated posttranscriptional mechanism that provides a new dimension into how the fundamental heme biosynthetic process is regulated as a determinant of erythrocyte development.

LncRNAs modulate diverse physiological cellular processes, however, their involvement in heme-dependent processes are not yet clear. Here the authors reveal the role of lncRNA UCA1 in erythroid cell development.

Predictive role of UCA1-containing exosomes in cetuximab-resistant colorectal cancer

Background

Primary or acquired resistance to cetuximab often occurs during targeted therapy in metastatic colorectal cancer (mCRC) patients. In many cancers, the key role of the long noncoding RNA (lncRNA) urothelial carcinoma-associated 1 (UCA1) in anticancer drug resistance has been confirmed. Emerging evidence has shown that specific exosomal lncRNAs may serve as meaningful biomarkers. In this study, we hypothesize that exosomal UCA1 might predict the response to cetuximab in CRC patients.

Methods

First, acquired cetuximab-resistant cell lines were generated, and UCA1 expressions in these cells and their exosomes were compared. We also systematically evaluate the stability of exosomal UCA1. Thereafter, the predictive value of exosomal UCA1 in CRC patients treated with cetuximab was evaluated. Finally, through cell apoptosis assays and immunofluorescence staining, we analyzed the role of UCA1-containing exosomes in conferring cetuximab resistance.

Results

UCA1 expression was markedly higher in cetuximab-resistant cancer cells and their exosomes. Exosomal UCA1 was shown to be detectable and stable in serum from CRC patients. In addition, circulating UCA1-containing exosomes could predict the clinical outcome of cetuximab therapy in CRC patients, and UCA1 expression was considerably higher in the progressive disease/stable disease patients than in the partial response/complete response patients. Furthermore, exosomes derived from cetuximab-resistant cells could alter UCA1 expression and transmit cetuximab resistance to sensitive cells.

Conclusions

We discovered a novel role of UCA1-containing exosomes, showed their capability to transmit drug resistance and investigated their potential clinical use in predicting cetuximab resistance.

LncRNA MAFG-AS1 promotes the progression of colorectal cancer by sponging miR-147b and activation of NDUFA4

Researchers have shown that long noncoding RNAs (lncRNAs) are closely associated with the pathogenesis of colorectal cancer (CRC). In here, we aimed to explore the function of lncRNA MAFG-AS1 in tumorigenesis of CRC. Firstly, we found that the expression of MAFG-AS1 was upregulated in CRC tissues and positively correlated with the advanced tumor stage. A reciprocal repression was found between MAFG-AS1 and miR-147b. The expression of miR-147b was downregulated in CRC tissues and inversely correlated with MAFG-AS1. Both the low-expression of miR-147b expression and the advanced tumor stage were independent factor for poor survival probability. Furthermore, overexpression of MAFG-AS1 promoted cell proliferation, cell cycle progression, and invasion, and inhibited apoptosis, while transduction of miR-147b partially reversed the effect of MAFG-AS1 on cellular processes. Consistently, stable over-expression of MAFG-AS1 contributed to the growth of colon cancer cell xenografts in vivo. NDUFA4 was identified as a direct target of miR-147b and knockdown of NDUFA4 abolished the oncogenic role of miR-147b inhibitor. Besides, MAFG-AS1 contributed to cell glycolysis by sponging miR-147b and activation of NDUFA4, causing an upregulation of PDK1, PFK1 and PKM2. Taken together, our study suggested that MAFG-AS1 functions as a novel oncogenic lncRNA in the development of CRC by regulating miR-147b/NDUFA4.

Knockdown of lncRNA UCA1 inhibits proliferation and invasion of papillary thyroid carcinoma through regulating miR-204/IGFBP5 axis

Background

Long noncoding RNA (LncRNA) UCA1 has been reported to function as an oncogene in multiple cancers. However, the biological roles and underlying mechanism of UCA1 in papillary thyroid carcinoma (PTC) remain unclear. This study aimed to investigate the underlying function of UCA1 on thyroid cancer progression.

Materials and methods

A series of experiments involving Cell Counting Kit-8, wound-healing, and transwell invasion assays were conducted to determine the cellular capabilities of proliferation, migration, and invasion, respectively. Binding sites between UCA1 and miR-204 were identified using a luciferase reporter system, whereas mRNA and protein expression of target genes were determined by real-time quantitative reverse transcription-PCR (qRT-PCR) and Western blot, respectively.

Results

The results revealed that UCA1 was upregulated in PTC tissue and cell lines. UCA1 knockdown significantly suppressed the cell proliferation, migration, and invasion of TPC-1 cells. Bioinformatics analysis and luciferase reporter assay verified the complementary binding within UCA1 and miR-204 at the 3′-UTR. Moreover, miR-204 inhibition reversed the UCA1 knockdown-mediated inhibitory effect on cell proliferation, migration, and invasion. We also found that UCA1 could regulate expression of IGFBP5, a direct target of miR-204 in PTC.

Conclusion

Our study demonstrated that UCA1 exerts activity of oncogenes in PTC through regulating miR-204/IGFBP5 axis.

The emerging role of long non-coding RNAs in the drug resistance of colorectal cancer

Colorectal cancer (CRC) remains one of the leading causes of cancer-related deaths in the world. Chemotherapy has been used to treat CRC patients in order to improve prognosis. Oxaliplatin and 5-Fluorouracil (5-FU) based chemotherapy is a first line treatment for locally advanced and metastatic CRC. For patients with wild-type KRAS metastatic CRC, cetuximab (an EGFR monoclonal antibody) is a commonly used targeted therapy. CRC is initially sensitive to chemotherapy and targeted therapy. However, drug resistance frequently arises, which significantly affect the treatment outcome in these patients. An increasing number of studies have indicated that lncRNAs are implicated in the drug resistance of CRC. This review aims to gain insights into the role and molecular mechanism of lncRNAs in CRC drug resistance.

LncRNA-FEZF1-AS1 Promotes Tumor Proliferation and Metastasis in Colorectal Cancer by Regulating PKM2 Signaling

Purpose: Long non-coding RNAs (lncRNAs) play key roles in human cancers. Here, FEZF1-AS1, a highly overexpressed lncRNA in colorectal cancer, was identified by lncRNA microarrays. We aimed to explore the roles and possible molecular mechanisms of FEZF1-AS1 in colorectal cancer.Experimental Design: LncRNA expression in colorectal cancer tissues was measured by lncRNA microarray and qRT-PCR. The functional roles of FEZF1-AS1 in colorectal cancer were demonstrated by a series of in vitro and in vivo experiments. RNA pull-down, RNA immunoprecipitation and luciferase analyses were used to demonstrate the potential mechanisms of FEZF1-AS1.Results: We identified a series of differentially expressed lncRNAs in colorectal cancer using lncRNA microarrays, and revealed that FEZF1-AS1 is one of the most overexpressed. Further validation in two expanded colorectal cancer cohorts confirmed the upregulation of FEZF1-AS1 in colorectal cancer, and revealed that increased FEZF1-AS1 expression is associated with poor survival. Functional assays revealed that FEZF1-AS1 promotes colorectal cancer cell proliferation and metastasis. Mechanistically, FEZF1-AS1 could bind and increase the stability of the pyruvate kinase 2 (PKM2) protein, resulting in increased cytoplasmic and nuclear PKM2 levels. Increased cytoplasmic PKM2 promoted pyruvate kinase activity and lactate production (aerobic glycolysis), whereas FEZF1-AS1-induced nuclear PKM2 upregulation further activated STAT3 signaling. In addition, PKM2 was upregulated in colorectal cancer tissues and correlated with FEZF1-AS1 expression and patient survival.Conclusions: Together, these data provide mechanistic insights into the regulation of FEZF1-AS1 on both STAT3 signaling and glycolysis by binding PKM2 and increasing its stability. Clin Cancer Res; 24(19); 4808-19. ©2018 AACR.

A ten-long non-coding RNA signature for predicting prognosis of patients with cervical cancer

Purpose

The aim of the present study was to construct a novel long non-coding RNA (lncRNA) signature to predict the prognosis of patients with cervical cancer (CC).

Materials and methods

We downloaded lncRNA expression profiles and clinical characteristics from The Cancer Genome Atlas database and randomly divided them into a training dataset (n=200) and a testing dataset (n=87). Using a Cox-based iterative sure independence screening procedure combined with a resampling technique, a lncRNA signature was calculated from prognostic lncRNAs in the training dataset and was independently verified in the testing and the entire datasets. In addition, multivariate Cox regression and further stratified analyses were performed, taking into consideration the lncRNA signature as well as other clinical characteristics. Finally, we predicted the underlying functional effects of the prognostic lncRNAs by using Gene Ontology and Kyoto Encyclopedia of Genes and Genomes pathway enrichment analyses.

Results

We constructed a promising ten-lncRNA signature that was significantly associated with the prognosis of CC on the basis of a risk score formula. The risk score was used to classify patients into high-risk and low-risk groups with different overall survival in the training dataset, and was confirmed in the testing and entire datasets. Compared with the clinical factors, the ten-lncRNA signature was found to be an independent prognostic indicator and displayed robust prognostic performance. A functional analysis indicated that these ten lncRNAs were enriched in immune response, cell adhesion molecules and nuclear factor kappa B signaling.

Conclusion

Our results demonstrated that this ten-lncRNA signature may serve as a prognostic biomarker for patients with CC.

The emerging role of lncRNAs in the regulation of cancer stem cells

BACKGROUND

Tumors contain a functional subpopulation of cells that exhibit stem cell properties. These cells, named cancer stem cells (CSCs), play significant roles in the initiation and progression of cancer. Long non-coding RNAs (lncRNAs) can act at the transcriptional, posttranscriptional and translational level. As such, they may be involved in various biological processes such as DNA damage repair, inflammation, metabolism, cell survival, cell signaling, cell growth and differentiation. Accumulating evidence indicates that lncRNAs are key regulators of the CSC subpopulation, thereby contributing to cancer progression. The aim of this review is to overview current knowledge about the functional role and the mechanisms of action of lncRNAs in the initiation, maintenance and regulation of CSCs derived from different neoplasms. These lncRNAs include CTCF7, ROR, DILC, HOTAIR, H19, HOTTIP, ATB, HIF2PUT, SOX2OT, MALAT-1, CUDR, Lnc34a, Linc00617, DYNC2H1-4, PVT1, SOX4 and ARSR Uc.283-plus. Furthermore, we will illustrate how lncRNAs may regulate asymmetric CSC division and contribute to self-renewal, drug resistance and EMT, thus affecting the metastasis and recurrence of different cancers. In addition, we will highlight the implications of targeting lncRNAs to improve the efficacy of conventional drug therapies and to hamper CSC survival and proliferation.

CONCLUSIONS

lncRNAs are valuable tools in the search for new targets to selectively eliminate CSCs and improve clinical outcomes. LncRNAs may serve as excellent therapeutic targets because they are stable, easily detectable and expressed in tissue-specific contexts.

Long noncoding RNA SNHG6 promotes the progression of colorectal cancer through sponging miR-760 and activation of FOXC1

Background

Colorectal cancer (CRC) is one of most common cancers worldwide. Long non-coding RNA SNHG6 has been reported to act as essential regulators in several cancers. However, the functional role and molecular mechanism of SNHG6 in colorectal cancer remain unclear.

Methods

Quantitative real-time polymerase chain reaction (PCR) was performed to evaluate the SNHG6 expression in CRC tissues. Colony formation, transwell assays and in vivo mice models were carried out to assess the effect of SNHG6 on CRC biological functions.

Results

In the present study, we showed that the expression of SNHG6 was significantly upregulated in CRC tissues and cell lines. High expression of SNHG6 was associated with shorter overall survival in CRC patients. Functionally, SNHG6 knockdown significantly inhibited cell proliferation, invasion and migration both in vitro and in vivo. Mechanically, miR-760 was a direct target of SNHG6, and repression of miR-760 could rescue the inhibitory effect of SNHG6 knockdown on CRC progression. In addition, SNHG6 positively regulated FOXC1 expression through sponging miR-760 in CRC cells, thus indicating that SNHG6 exerted an oncogenic role in CRC by acting as a ceRNA of miR-760.

Conclusion

Our results indicate that long non-coding RNA SNHG6 promotes colorectal cancer progression by sequestering miR-760 and activating FOXC1, our findings suggest that SNHG6 may serve as a potential therapeutic target for CRC.

Long Non-Coding RNAs as New Master Regulators of Resistance to Systemic Treatments in Breast Cancer

Predicting response to systemic treatments in breast cancer (BC) patients is an urgent, yet still unattained health aim. Easily detectable molecules such as long non-coding RNAs (lncRNAs) are the ideal biomarkers when they act as master regulators of many resistance mechanisms, or of mechanisms that are common to more than one treatment. These kinds of markers are pivotal in quasi-personalized treatment selection, and consequently, in improvement of outcome prediction. In order to provide a better approach to understanding development of disease and resistance to treatments, we reviewed current literature searching for lncRNA-associated systemic BC treatments including endocrine therapies, aromatase inhibitors, selective estrogen receptor modulators (SERMs), trastuzumab, paclitaxel, docetaxel, 5-fluorouracil (5-FU), anthracyclines, and cisplatin. We found that the engagement of lncRNAs in resistance is well described, and that lncRNAs such as urotelial carcinoma-associated 1 (UCA1) and regulator of reprogramming (ROR) are indeed involved in multiple resistance mechanisms, which offers tantalizing perspectives for wide usage of lncRNAs as treatment resistance biomarkers. Thus, we propose this work as the foundation for a wide landscape of functions and mechanisms that link more lncRNAs to resistance to current and new treatments in years of research to come.

Screening key long non-coding RNAs in early-stage colon adenocarcinoma by RNA-sequencing

AIM

We aim to identify the key long noncoding RNAs (lncRNAs) in early-stage colon adenocarcinoma (COAD).

PATIENTS & METHODS

Compared with colonic intraepithelial neoplasia, differentially expressed lncRNAs (DElncRNAs) in early-stage COAD were obtained by RNA-sequencing. Our previous work has obtained the differentially expressed mRNAs and miRNAs (DEmRNAs and DEmiRNAs) in early-stage COAD. DEmiRNA-DElncRNA-DEmRNA interaction analysis and functional annotation were performed. Validation of expression and receiver-operating characteristic analyses were performed based on The Cancer Genome Atlas.

RESULTS

Seventy-nine significantly DElncRNAs in early-stage COAD were obtained. MiR-153-3p-TUG1-DAPK1/ARNT2/KLK3/PLD1/SMAD2 and miR-153-3p-SNHG17-COL11A1/IGFBP3/KLF6 interactions were associated with early-stage COAD. Five DElncRNAs (ELFN1-AS1, LINC01234, SNHG17, UCA1 and LOC101929549) involved in early-stage COAD with potential diagnostic value.

CONCLUSION

LncRNAs involve in early-stage COAD by interaction with COAD-regulated genes and miRNAs.

Emerging roles of long non-coding RNAs in tumor metabolism

Compared with normal cells, tumor cells display distinct metabolic characteristics. Long non-coding RNAs (lncRNAs), a large class of regulatory RNA molecules with limited or no protein-coding capacity, play key roles in tumorigenesis and progression. Recent advances have revealed that lncRNAs play a vital role in cell metabolism by regulating the reprogramming of the metabolic pathways in cancer cells. LncRNAs could regulate various metabolic enzymes that integrate cell malignant transformation and metabolic reprogramming. In addition to the known functions of lncRNAs in regulating glycolysis and glucose homeostasis, recent studies also implicate lncRNAs in amino acid and lipid metabolism. These observations reveal the high complexity of the malignant metabolism. Elucidating the metabolic-related functions of lncRNAs will provide a better understanding of the regulatory mechanisms of metabolism and thus may provide insights for the clinical development of cancer diagnostics, prognostics and therapeutics.

Knockdown of long noncoding RNA urothelial carcinoma-associated 1 inhibits cell viability, migration, and invasion by regulating microRNA-182 in gastric carcinoma

BACKGROUND

Long noncoding RNA urothelial carcinoma-associated 1 (UCA1) has been reported to be a vital mediator in various cancers. But, in terms of gastric cancer (GC), the effects of UCA1 on GC cell proliferation, migration, invasion, and apoptosis remain unclear. This study aimed to uncover the potential regulatory mechanism of UCA1 in GC cells.

METHODS

The expression level of UCA1 was first examined in the five different cell lines of HEK293, CCL-153, HUVEC, SUN-216, and SGC-7901 using a reverse-transcriptase quantitative polymerase chain reaction. Then, the vectors of short hairpin UCA1, the microRNA-182 (miR-182) mimic/inhibitor, and the pEX-tissue inhibitor of metalloproteinases 2 (TIMP2)/small interfering TIMP2 were transfected into SUN-216 and SGC-7901 cells to alter UCA1, miR-182, and TIMP2 expression. To investigate the biological functions, cell viability, migration, invasion, and apoptosis were examined by Cell Counting Kit-8, Transwell, and flow cytometry. The key factors of apoptosis and phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase 3β (GSK3β) and nuclear factor κB (NF-κB) signal pathways were determined by Western blot analysis.

RESULTS

UCA1 was upregulated in SUN-216 and SGC-7901 cells than in the other three cell lines of HEK293, CCL-153, and HUVEC. Knockdown of UCA1 significantly suppressed cell viability, migration, and invasion, and promoted apoptosis by regulating B-cell lymphoma 2, Bax, and cleaved-caspase-3/9 expressions. However, miR-182 overexpression markedly reversed the regulatory effect of UCA1 knockdown on SUN-216 and SGC-7901 cells. TIMP2 was a direct target gene of miR-182, and TIMP2 overexpression exhibited the same effect of UCA1 knockdown on cell viability, migration, invasion, and apoptosis. Besides, miR-182 activated PI3K/AKT/GSK3β and NF-κB signal pathways by regulation of TIMP2.

CONCLUSION

Knockdown of UCA1 exerts an anticancer effect on GC cells by regulating miR-182.

LncRNA UCA1 sponges miR-204-5p to promote migration, invasion and epithelial-mesenchymal transition of glioma cells via upregulation of ZEB1

Long non-coding RNA urothelial carcinoma associated 1 (lncRNA UCA1) promotes cancer progression and enhances chemoresistance through miR-204-5p in a few cancers. However, no studies have investigated whether UCA1 regulates glioma metastasis through miR-204-5p and its target. In the present study, cell migration, invasion and epithelial-mesenchymal transition (EMT) were evaluated in glioma cells overexpressing UCA1. The relationships among UCA1, miR-204-5p and ZEB1 were examined by real-time PCR, western blotting and dual-luciferase reporter assays. The effect of UCA1 knockdown on xenograft tumor growth was investigated. The levels of miR-204-5p, fibronectin, COL5 A1 and ZEB1 in tumor tissues were also determined. The results showed that UCA1 overexpression promoted cell migration, invasion and EMT. UCA1 interacted with miR-204-5p and decreased its level. ZEB1 was identified as a direct target of miR-204-5p and miR-204-5p negatively regulated ZEB1 expression. Moreover, UCA1 sponged miR-204-5p and partially rescued the inhibitory effect of miR-204-5p on ZEB1. In our in vivo studies, UCA1 knockdown reduced tumor volume and tumor weight. In addition, the levels of fibronectin, COL5 A1 and ZEB1 were decreased, while miR-204-5p level was increased. The present study provides the first evidence that UCA1 promotes glioma metastasis through the miR-204-5p/ZEB1 axis, contributing to the understanding of the pathogenesis of glioma.

Long non‑coding RNA UCA1 promotes papillary thyroid cancer cell proliferation via miR‑204‑mediated BRD4 activation

Long non‑coding RNA (lncRNA) urothelial carcinoma‑associated 1 (UCA1) has been used in tumor development and progression in many types of cancer. However, the function and mechanism underlying the action of UCA1 in papillary thyroid cancer (PTC) remains unclear. Therefore, these topics were investigated in the present study by in vitro and in vivo experiments. It was demonstrated that the expression level of UCA1 was more significantly upregulated in PTC cell lines and tissues when compared with the immortal human thyroid follicular cell line and adjacent normal tissues, respectively. UCA1 knockdown significantly inhibited PTC cell viability, colony formation and the bromodomain containing 4 (BRD4) expression level in vitro, and retarded PTC tumor growth in vivo. In the previous study, microRNA (miR)‑204 inhibited thyroid cancer progression and was regulated by UCA1 in other types of cancer. In addition, by conducting dual luciferase reporter assays, it was confirmed that miR‑204 directly binds to UCA1 and the 3'‑untranslated region of BRD4. Furthermore, UCA1 competed with BRD4 for miR‑204 binding. miR‑204 knockdown enhanced BRD4 expression, which can be partially restored by short hairpin‑UCA1. The results of the present study illustrated that UCA1 promotes PTC progression by acting as a competing endogenous RNA by sponging miR‑204. In conclusion, UCA1 may be regarded as an oncogenic lncRNA, promoting PTC cell proliferation, and be a potential target for human PTC treatment.

Linc00472 suppresses proliferation and promotes apoptosis through elevating PDCD4 expression by sponging miR-196a in colorectal cancer

Long intergenic non-coding RNA Linc00472 has been considered as a tumor suppressor in some cancers. However, the function and mechanism of Linc00472 in colorectal cancer has not been well elucidated. In this study, we found that Linc00472 was down-regulated in colorectal cancer tissues and cells. Elevated Linc00472 expression suppressed proliferation and induced apoptosis in colorectal cancer cells. Moreover, Linc00472 acted as a competing endogenous RNA (ceRNA) of miR-196a to release programmed cell death 4 (PDCD4). Furthermore, miR-196a overexpression or PDCD4 knockdown reversed Linc00472-mediated proliferation inhibition and apoptosis induction in colorectal cancer cells. Ectopic Linc00472 expression hindered tumor growth in vivo. Our study demonstrated that Linc00472 suppressed proliferation and induced apoptosis through up-regulating PDCD4 by decoying miR-196a, which may be an effective therapeutic target for colorectal cancer.

Non-Coding RNAs and Resistance to Anticancer Drugs in Gastrointestinal Tumors

Non-coding RNAs are important regulators of gene expression and transcription. It is well established that impaired non-coding RNA expression especially the one of long non-coding RNAs and microRNAs is involved in a number of pathological conditions including cancer. Non-coding RNAs are responsible for the development of resistance to anticancer treatments as they regulate drug resistance-related genes, affect intracellular drug concentrations, induce alternative signaling pathways, alter drug efficiency via blocking cell cycle regulation, and DNA damage response. Furthermore, they can prevent therapeutic-induced cell death and promote epithelial-mesenchymal transition (EMT) and elicit non-cell autonomous mechanisms of resistance. In this review, we summarize the role of non-coding RNAs for different mechanisms resulting in drug resistance (e.g., drug transport, drug metabolism, cell cycle regulation, regulation of apoptotic pathways, cancer stem cells, and EMT) in the context of gastrointestinal cancers.

Cancer-associated fibroblasts enhance cell proliferation and metastasis of colorectal cancer SW480 cells by provoking long noncoding RNA UCA1

Cancer-associated fibroblasts (CAFs) have been considered as major players in tumor growth and malignancy. In colorectal cancer (CRC), CAFs are attendance in high affluence and little is known about how they impact tumor progression. An increasing number of studies indicated that dysregulation of human urothelial carcinoma associated 1 (UCA1) is associated with progression of tumor and metastasis in various cancers including CRC. Nonetheless, the possible mechanisms of UCA1 actuation in CRC remain poorly understood. To address this, we elucidated the effects of conditioned medium from SW480 CRC cells/Normal fibroblast co-culture (CAF-CM) on UCA1 expression, and the cell proliferation, EMT, invasion and migration of the treated CRC cell were evaluated in vitro. Our study indicated that CAFs dramatically stimulated cell proliferation and migration of CRC cell. Furthermore, CAFs induced the EMT phenotype in CRC cell, with an associated change in the expression of EMT markers including vimentin, E-cadherin, N-cadherin and metastasis-related genes (MMPs). Moreover, we found an increased percentage of CRC cell in the S and G2/M phase induced by CAFs. Our results revealed that CAFs could induce upregulation of UCA1, leading to upregulation of mTOR. Up-regulation of UCA1/mTOR axis suppressed p27 and miR-143 while the expression of Cyclin-D1 and KRAS were significantly increased compared with control. Furthermore, UCA1 silencing in treated CRC cell suggested that upregulation of UCA1, which was induced by CAFs, regulates the expression of downstream key effectors. Taken together, these results highlight the vital role of cooperation between lncRNA UCA1 and mTOR in proliferation and metastasis which support the hypothesis that CAFs may be a prominent therapeutic target of stroma-based therapy in CRC treatment.

Emerging role of long non-coding RNAs in cisplatin resistance

Cisplatin (CDDP) is one of the most commonly used chemotherapy drugs for the treatment of various cancers. Although platinum-based therapies are highly efficacious against rapidly proliferating malignant tumors, the development of CDDP resistance results in significant relapse as well as decreased overall survival rates, which is a significant obstacle in CDDP-based cancer therapy. Long non-coding RNAs (lncRNAs) are involved in cancer development and progression by the regulation of processes related to chromatin remodeling, transcription, and posttranscriptional processing. Emerging evidence has recently highlighted the roles of lncRNAs in the development of CDDP resistance. In this review, we discuss the roles and mechanisms of lncRNAs in CDDP chemoresistance, including changes in cellular uptake or efflux of a drug, intracellular detoxification, DNA repair, apoptosis, autophagy, cell stemness, and the related signaling pathways, aiming to provide potential lncRNA-targeted strategies for overcoming drug resistance in cancer therapy.

Roles of long noncoding RNAs in colorectal cancer metastasis

Colorectal cancer (CRC) is the 3^rd most common malignancies worldwide. Metastasis is responsible for more than 90% CRC patients' death. Long noncoding RNAs (lncRNAs) are an important class of transcribed RNA molecules greater than 200 nucleotides in length. With the development of whole genome sequencing technologies, they have been gained more attention. Accumulating evidences suggest that abnormal expression of lncRNAs in diverse diseases are involved in various biological functions such as proliferation, apoptosis, metastasis and differentiation by acting as epigenetic, splicing, transcriptional or post-transcriptional regulators. Aberrant expression of lncRNAs has also been found in CRC. Besides, recent studies have indicated that lncRNAs play important roles in tumourigenesis and cancer metastasis. They participate in the process of metastasis by activing or inhibiting the metastatic pathways. However, their functions on the development of cancer metastasis are poorly understood. In this review, we highlight the findings of roles for lncRNAs in CRC metastasis and review the metastatic pathways of lncRNAs leading to cancer metastasis in CRC, including escape of apoptosis, epithelial-mesenchymal transition (EMT), angiogenesis and invasion, migration and proliferation. Furthermore, we also discuss the potential clinical application of lncRNAs in CRC as diagnostic markers and therapeutic targets.

Up-regulated expression of SNHG6 predicts poor prognosis in colorectal cancer

Long non-coding RNAs (lncRNAs) have been shown to play important roles in tumor formation and development. Small nucleolar RNA host gene 6 (SNHG6) is a recently identified cancer-related lncRNA, and its role in colorectal cancer (CRC) remains to be explored. The aim of this study was to evaluate the expression and function of SNHG6 in CRC. The expression of SNHG6 was detected by real time quantitative RT-PCR (qRT-PCR) in 74 CRC tissues and matched noncancerous tissues (NCTs). Relationships between the expression levels of SNHG6 and various clinicopathological features were analyzed by Chi-square test. The Kaplan-Meier method and log-rank test were applied to compare the survival distribution between different groups. CCK8 assay and colony formation assay were used to measure the effect of SNGH6 on cell proliferation. Flow cytometric analysis was performed to measure the effect of SNHG6 on cell cycle and apoptosis. Our results showed that SNHG6 was up-regulated more than 1.5-fold in 50.0% (37/74) of CRC tissues compared with paired NCTs (P < 0.0001). High level of SNHG6 expression was strongly associated with advanced tumor stage (P = 0.026) and predicted poor prognosis of CRC (P = 0.0215). The Cox proportional hazards model demonstrated that SNHG6 expression was an independent prognostic factor for CRC (HR, 2.568; 95% CI, 1.055-6.252; P = 0.038). Furthermore, SNHG6 knockdown by siRNA could inhibit cell proliferation, cell cycle progression, and induce apoptosis. Taken together, SNHG6 functions as an oncogene in CRC and appears as a novel prognositic factor for CRC patients.

IMP1 regulates UCA1-mediated cell invasion through facilitating UCA1 decay and decreasing the sponge effect of UCA1 for miR-122-5p

BACKGROUND

Long noncoding RNAs (LncRNAs) represent a class of widespread and diverse endogenous RNAs that can posttranscriptionally regulate gene expression through the interaction with RNA-binding proteins and micro RNAs (miRNAs). Here, we report that in breast carcinoma cells, the insulin-like growth factor 2 messenger RNA binding protein (IMP1) binds to lncRNA urethral carcinoma-associated 1 (UCA1) and suppresses the UCA1-induced invasive phenotype.

METHODS

RT-qPCR and RNA sequence assays were used to investigate the expression of UCA1 and miRNAs in breast cancer cells in response to IMP1 expression. The role of IMP1-UCA1 interaction in cell invasion was demonstrated by transwell analysis through loss-of-function and gain-of-function effects. RNA pull-down and RNA binding protein immunoprecipitation (RIP) were performed to confirm the molecular interactions of IMP1-UCA1 and UCA1-miR-122-5p involved in breast cancer cells.

RESULTS

In breast cancer cells, IMP1 interacts with UCA1 via the "ACACCC" motifs within UCA1 and destabilizes UCA1 through the recruitment of CCR4-NOT1 deadenylase complex. Meanwhile, binding of IMP1 prevents the association of miR-122-5p with UCA1, thereby shifting the availability of miR-122-5p from UCA1 to the target mRNAs and reducing the UCA1-mediated cell invasion. Accordingly, either IMP1 silencing or UCA1 overexpression resulted in reduced levels of free miR-122-5p within the cytoplasm, affecting miR-122-5p in regulating its target mRNAs.

CONCLUSIONS

Our study provides initial evidence that interaction between IMP1 and UCA1 enhances UCA1 decay and competes for miR-122-5p binding, leading to the liberation of miR-122-5p activity and the reduction of cell invasiveness.

Regulatory network analysis of LINC00472, a long noncoding RNA downregulated by DNA hypermethylation in colorectal cancer

Colorectal cancer (CRC), one of the common malignant cancers in the world, is caused by accumulated alterations of genetic and epigenetic factors over a long period of time. Along with that protein-coding genes being identified as oncogenes or tumor suppressors in CRC, a number of lncRNAs have also been found to be associated with CRC. Considering the important regulatory role of lncRNAs, the first goal of this study was to identify CRC-associated lncRNAs from a public database. One such lncRNA, LINC00472, was verified to be downregulated in CRC cell lines and cancer tissues compared with adjacent tissues. In addition, the down-regulation of LINC00472 seemed to be caused by DNA hypermethylation at its promoter region. Furthermore, the expression of LINC00472 and DNA methylation of promoter were significantly correlated with clinicopathological features. And DNA hypermethylation of LINC00472 may serve as a better diagnostic biomarker than its expression for CRC. Finally, we predicted the functions of LINC00472 and constructed a regulatory network and found LINC00472 may be involved in cell cycle and cell proliferation processes. Our results may provide a clue to further research into the function and regulatory mechanism of LINC00472 in CRC.

The prognostic significance of UCA1 for predicting clinical outcome in patients with digestive system malignancies

Background

Urothelial Carcinoma Associated 1 (UCA1) was an originally identified lncRNA in bladder cancer. Previous studies have reported that UCA1 played a significant role in various types of cancer. This study aimed to clarify the prognostic value of UCA1 in digestive system cancers.

Results

The meta-analysis of 15 studies were included, comprising 1441 patients with digestive system cancers. The pooled results of 14 studies indicated that high expression of UCA1 was significantly associated with poorer OS in patients with digestive system cancers (HR: 1.89, 95 % CI: 1.52–2.26). In addition, UCA1 could be as an independent prognostic factor for predicting OS of patients (HR: 1.85, 95 % CI: 1.45–2.25). The pooled results of 3 studies indicated a significant association between UCA1 and DFS in patients with digestive system cancers (HR = 2.50; 95 % CI = 1.30–3.69). Statistical significance was also observed in subgroup meta-analysis. Furthermore, the clinicopathological values of UCA1 were discussed in esophageal cancer, colorectal cancer and pancreatic cancer.

Materials and methods

A comprehensive retrieval was performed to search studies evaluating the prognostic value of UCA1 in digestive system cancers. Many databases were involved, including PubMed, Web of Science, Embase and Chinese National Knowledge Infrastructure and Wanfang database. Quantitative meta-analysis was performed with standard statistical methods and the prognostic significance of UCA1 in digestive system cancers was qualified.

Conclusions

Elevated level of UCA1 indicated the poor clinical outcome for patients with digestive system cancers. It may serve as a new biomarker related to prognosis in digestive system cancers.

LncRNA UCA1 impacts cell proliferation, invasion, and migration of pancreatic cancer through regulating miR-96/FOXO3

This study was expected to reveal the regulatory effects of lncRNA UCA1 on pancreatic cancer cell progression through targeting miR-96/FOXO3. Microarray analysis was carried out on 36 cases of pancreatic cancer tissues and 16 cases of adjacent tissues among them. Expression levels of lncRNA UCA1, miR-96, and FOXO3 in pancreatic cancer tissues and cell lines were determined by qRT-PCR. Expression levels of FOXO3 protein were determined by western blot. Cell viability, cell cycle and apoptosis, cell invasion and migration were detected by CCK-8, flow cytometry, and transwell assay, respectively. The colocalization relationship between lncRNA UCA1 and miR-96 was detected by RNA FISH. Whether UCA1 could target miR-96 and whether miR-96 could target FOXO3 3'UTR were verified by dual-luciferase reporter gene assay. High expression of lncRNA UCA1 and FOXO3 and low expression of miR-96 were shown in pancreatic cancer. Inhibition of UCA1 suppressed pancreatic tumor cell proliferation, colony formation, and metastasis, while inhibition of miR-96 promoted pancreatic cancer cell progression. FOXO3 was the downstream target gene of miR-96 and showed the opposite effects. LncRNA UCA1 promoted cell proliferation, invasion, migration and inhibited cell apoptosis of pancreatic cancer through down-regulating miR-96 and up-regulating FOXO3. © 2018 IUBMB Life, 70(4):276-290, 2018.

UCA1 promotes cell proliferation and invasion of gastric cancer by targeting CREB1 sponging to miR-590-3p

Long noncoding RNAs (lncRNAs) have emerged as regulators in a variety of biological processes, including carcinogenesis in human cancer. UCA1 has been reported to be upregulated in gastric cancer (GC); however, the underlying functional roles of UCA1 in GC have not been established. In the current study, we showed that UCA1 is significantly higher in GC tissues and cells compared with adjacent normal tissues and a gastric epithelium cell line, respectively. Higher UCA1 expression was associated with lymph node metastasis, TNM stage, and poor overall survival (OS) in GC patients. In vitro functional studies confirmed that UCA1 promotes cell proliferation, colony formation ability, and cell invasion in GC cells. We demonstrated that knockdown of UCA1 inhibits tumor growth in vivo. The double luciferase reporter, RNA‐binding protein immunoprecipitation assay, and RNA pull down assay demonstrated that miR‐590‐3p serves as a target for UCA1. UCA1 promoted cell proliferation and invasion by negatively regulating miR‐590‐3p expression. Moreover, we demonstrated that CREB1 is a downstream target of miR‐590‐3p and UCA1 activates CREB1 expression by sponging to miR‐590‐3p. Thus, these results showed that UCA1 functions as an oncogene in GC and may be a target for treatment of GC.

Prognostic and clinicopathological role of long non-coding RNA UCA1 in various carcinomas

Urothelial cancer associated 1 (UCA1) as an oncogenic long non-coding RNA (LncRNA) was aberrantly upregulated in various solid tumors. Numerous studies have demonstrated overexpression of UCA1 is an unfavorable prognostic indicator in cancer patients. This study aimed to further explore the prognosis role and clinical significance of UCA1 in cancer. Eligible studies were recruited by a systematic search in PubMed, Embase, Cochrane Library and Web of Science databases. A total of 19/16 studies with 1587/1291 cancer patients were included to evaluate the association between UCA1 expression and overall survival (OS) and clinicopathological factors of malignancies by computing hazard ratio (HR), odds ratios (OR) and confidence interval (CI). The meta-analysis indicated overexpression of UCA1 was significantly correlated with unexpected OS in patients with cancer (pooled HR = 1.85, 95% CI 1.62-2.10, p < 0.001). There was also a significantly negative association between high level of UCA1 and poor grade cancer (pooled OR = 2.74, 95% CI 2.04-3.70, p < 0.001) and positive lymphatic metastasis (pooled OR = 2.43, 95% CI 1.72-3.41, p < 0.001). In conclusion, our study suggested that UCA1 was correlated with more advanced clinicopathological features and poor prognosis as a novel predictive biomarker of patients with various tumors.

Genetic and epigenetic silencing of mircoRNA-506-3p enhances COTL1 oncogene expression to foster non-small lung cancer progression

Although previous studies suggested that microRNA-506-3p (miR-506-3p) was frequently downregulated, and functioned as a tumor suppressor in several cancers, the biological role and intrinsic regulatory mechanisms of miR-506-3p in non-small cell lung cancer (NSCLC) remain elusive. The present study found miR-506-3p expression was downregulated in advanced NSCLC tissues and cell lines. The expression of miR-506-3p in NSCLC was inversely correlated with larger tumor size, advanced TNM stage and lymph node metastasis. In addition, we also found patients with lower expression of miR-506-3p had a poor prognosis than those patients with higher expression of miR-506-3p. Function studies demonstrated that aberrant miR-506-3p expression modulates tumor cell growth, cell mobility, cell migration and invasion in vitro and in vivo. Mechanistic investigations manifested that coactosin-like protein 1 (COTL1) was a direct downstream target of miR-506-3p. Knockdown of COTL1 mimicked the tumor-suppressive effects of miR-506-3p overexpression in A549 cells, whereas COTL1 overexpression enhanced the tumorigenic function in HCC827 cells. Importantly, we also found GATA3 transcriptionally actives miR-506-3p expression, and the long non-coding RNA urothelial carcinoma-associated 1 (UCA1) exerts oncogenic function in NSCLC by competitively ‘sponging’ miRNA-506. Together, our combined results elucidated genetic and epigenetic silencing of miR-506-3p enhances COTL1 oncogene expression to foster NSCLC progression.

Exosomes in Cancer Liquid Biopsy: A Focus on Breast Cancer

The important challenge about cancer is diagnosis in primary stages and proper treatment. Although classical clinico-pathological features of the tumor have major prognostic value, the advances in diagnosis and treatment are indebted to discovery of molecular biomarkers and control of cancer in the pre-invasive state. Moreover, the efficiency of available therapeutic options is highly diminished, and chemotherapy is still the main treatment due to lack of enough specific targets. Accordingly, finding the new noninvasive biomarkers for cancer is still an important clinical challenge that is not achieved yet. There are current technologies to screen, diagnose, prognose, and treat cancer, but the limitations of these implements and procedures are undeniable. Liquid biopsy as a noninvasive method has a promising future in the field of cancer, and exosomes as one of the recent areas have drawn much attention. In this review, the potential capability of exosomes is summarized in cancer with the special focus on breast cancer as the second cause of cancer mortality in women all around the world. It discusses reasons to choose exosomes for liquid biopsy and the studies related to different potential biomarkers found in the exosomes. Moreover, exosome studies on milk as a specific biofluid are also discussed. At last, because choosing the method for exosome studies is very challenging, a summary of different techniques is provided.

Prognostic value of long non-coding RNA UCA1 in human solid tumors

Background

Numerous studies have shown that the expression of UCA1 was aberrantly upregulated in various cancer types. High expression of UCA1 was reported to be associated with unfavorable prognosis in cancer patients.

Results

A total of 1240 patients from 15 articles were included. The results indicated that a significantly shorter OS was observed in patients with high expression level of UCA1 (HR = 1.71, 95% CI: 1.43–1.99), in the subgroup analysis, the association was also observed in patients with cancers of digestive system (HR = 2.12, 95% CI: 1.59–2.66). Statistical significance was also observed in subgroup meta-analysis stratified by the cancer type, cut-off value, analysis type and sample size. Furthermore, poorer DFS was observed in patients with high expression level of UCA1 (HR = 2.54; 95% CI: 1.09–4.00). Additionally, the pooled odds ratios (ORs) showed that increased UCA1 was also related to positive lymph node metastasis (OR = 2.98, 95% CI: 2.06–4.30), distant metastasis (OR = 3.14, 95% CI: 1.77–5.58) and poor clinical stage (OR = 2.76, 95% CI: 2.08–3.68).

Materials and Methods

A comprehensive retrieval was conducted in multiple databases, including PubMed, Embase, Web of Science and CNKI. We collected relevant articles to explore the association between the expression levels of UCA1 and prognosis.

Conclusions

High expression level of UCA1 was associated with poor clinical outcome. UCA1 could serve as a novel biomarker for prognosis and might be a potential predictive factor for clinicopathological characteristics in various cancers. Further studies should be performed to verify the clinical utility of UCA1 in human solid tumors.

RAB22A overexpression promotes the tumor growth of melanoma

Malignant melanoma is the most aggressive type of skin cancer. RAB22A, a member of RAS oncogene family, has been found to be significantly upregulated in multiple human cancers. In the present study, we found that RAB22A mRNA expression was significantly upregulated in melanoma tissues (including 60 primary melanomas and 84 metastatic melanomas) compared to benign nevi (n = 20), which were significantly higher in metastatic melanoma tissues than primary tissues. Immunohistochemistry data further showed that the positive immunoreactivity of RAB22A was detected in 66% (95/144) melanoma tissues, but not in benign nevi. Moreover, high expression of RAB22A was significantly associated with advanced clinical stage in melanoma. Furthermore, patients with high RAB22A expression had shorter overall survival compared those with low expression of RAB22A. In-vitro study showed that RAB22A was also upregulated in melanoma cell lines WM35, A375, WM451, and SK-MEL-1, when compared with the normal melanocyte HM cells. Knockdown of RAB22A significantly reduced the proliferation, migration and invasion of melanoma A375 cells, while overexpression of RAB22A significantly promoted these malignant phenotypes. In addition, RAB22A was found to be a target of miR-203, a tumor suppressive miRNA in melanoma. Besides, miR-203 was downregulated in melanoma tissues and cell lines, when compared with benign nevi and HM cells, respectively. Taken these findings together, our study could validate an oncogenic role of RAB22A in melanoma, suggesting that RAB22A may be a potential therapeutic target for melanoma.

Downregulation of the long non-coding RNA XLOC_010588 inhibits the invasion and migration of colorectal cancer

Long non-coding RNAs (lncRNAs) have emerged as major players in many biological and pathological processes; however, investigation into the function of lncRNAs in the development and progression of cancer is in its infancy. Therefore, clarification of the mechanism by which cancer-related lncRNAs function is of critical importance in research on tumorigenesis. It has been demonstrated that the lncRNA XLOC_010588 is expressed at a low level in cervical cancer, and that this has significant impact on the proliferation of cervical cancer cells. However, the expression pattern and functional roles of XLOC_010588 in colorectal cancer (CRC) remain unclear. In the present study, it was demonstrated that the expression of XLOC_010588 was significantly higher in CRC tissues when compared with that in adjacent normal tissues, and that XLOC_010588 was closely associated with metastasis and poor prognosis, thus indicating that XLOC_010588 may function as an oncogene. Additionally, downregulation of XLOC_010588 expression markedly inhibited the invasion and migration of CRC cells. Furthermore, it was demonstrated that XLOC_010588 may regulate the progression of CRC via the epithelial-mesenchymal transition (EMT) pathway. Notably, downregulation of XLOC_010588 inhibited the invasion and migration of CRC cells by regulating genes associated with EMT. Our findings revealed that XLOC_010588 may be considered as a novel potential diagnostic biomarker in CRC.

Long non-coding RNA UCA1 desensitizes breast cancer cells to trastuzumab by impeding miR-18a repression of Yes-associated protein 1

Breast cancer resistance to the monoclonal erbB2/HER2 antibody trastuzumab (or herceptin) has become a significant obstacle in clinical targeted therapy of HER2-positive breast cancer. Previous research demonstrated that such drug resistance may be related to dysregulation of miRNA expression. Here, we found that knockdown of the long non-coding RNA, urothelial cancer associated 1 (UCA1), can promote the sensitivity of human breast cancer cells to trastuzumab. Mechanistically, UCA1 knockdown upregulated miR-18a and promoted miR-18a repression of Yes-associated protein 1 (YAP1). A luciferase reporter assay confirmed the association of miR-18a with wild-type UCA1 but not with UCA1 mutated at the predicted miR-18a-binding site. The direct targeting of YAP1 by miR-18a was verified by the observation that miR-18a mimic suppressed luciferase expression from a construct containing the YAP1 3' untranslated region. Meanwhile, reciprocal repression of UCA1 and miR-18a were found to be Argonaute 2-dependent. Knockdown of YAP1 recapitulated the effect of UCA1 silencing by reducing the viability of trastuzumab-treated breast cancer cells, whereas inhibition of miR-18a abrogated UCA1 knockdown-induced improvement of trastuzumab sensitivity in breast cancer cells. These findings demonstrate that the UCA1/miR-18a/YAP1 axis plays an important role in regulating the sensitivity of breast cancer cells to trastuzumab, which has implications for the development of novel approaches to improving breast cancer responses to targeted therapy.

miR-34a increases the sensitivity of colorectal cancer cells to 5-fluorouracil in vitro and in vivo

This study was designed to investigate the significance of the effect of miR-34a on 5-fluorouracil (5-FU) sensitivity in vitro and in vivo. miR-34a expression in tumor tissues or serum was determined by quantitative polymerase chain reaction. CRC cell lines HCT116 and SW480 were used to evaluate cell viability, cell apoptosis, and the cell cycle using a cell proliferation assay, flow cytometry, and Western blotting, respectively. For the in vivo studies, xenografts derived from SW480 cells were established to assess the antitumor activity between miR-34a and 5-FU. Patients with high levels of miR-34a expression were found to benefit more from 5-FU-based chemotherapy than patients with low levels of miR-34a expression, regardless of disease stage. Ectopic expression of miR-34a alone or 5-FU alone was found to inhibit CRC cell growth in vitro and in vivo. Moreover, cell growth in vitro and in vivo was further inhibited when miR-34a combined with 5-FU through increasing the rate of cell apoptosis. The potential targets of miR-34a, including CREB1, Bcl-2, Notch 1, Sirt1, and E2F3, were predicted and preliminarily validated and merit further study.

CONCLUSION

miR-34a might function as a predictor of fluorouracil chemosensitivity in CRC, and a combination strategy of miR-34a with fluorouracil was expected to be more beneficial for CRC patients.

Long Noncoding RNA UCA1 Targets miR-122 to Promote Proliferation, Migration, and Invasion of Glioma Cells

Glioma is the most common and lethal malignant intracranial tumor. Long noncoding RNAs (lncRNAs) have been identified as pivotal regulators in the tumorigenesis of glioma. However, the role of lncRNA urothelial carcinoma-associated 1 (UCA1) in glioma genesis is still unknown. The purpose of this study was to investigate the underlying function of UCA1 on glioma genesis. The results demonstrated that UCA1 was upregulated in glioma tissue and indicated a poor prognosis. UCA1 knockdown induced by si-UCA1 significantly suppressed the proliferative, migrative, and invasive activities of glioma cell lines (U87 and U251). Bioinformatics analysis and luciferase reporter assay verified the complementary binding within UCA1 and miR-122 at the 3'-UTR. Functional experiments revealed that UCA1 acted as an miR-122 "sponge" to modulate glioma cell proliferation, migration, and invasion via downregulation of miR-122. Overall, the present study demonstrated that lncRNA UCA1 acts as an endogenous sponge of miR-122 to promote glioma cell proliferation, migration, and invasion, which provides a novel insight and therapeutic target in the tumorigenesis of glioma.

The Immune-microenvironment Confers Chemoresistance of Colorectal Cancer through Macrophage-Derived IL6

Purpose: Tumor-associated macrophages (TAMs) are frequently associated with poor prognosis in human cancers. However, the effects of TAMs in colorectal cancer are contradictory. We therefore investigated the functions, mechanisms, and clinical significance of TAMs in colorectal cancer.Experimental Design: We measured the macrophage infiltration (CD68), P-gp, and Bcl2 expression in colorectal cancer tissues using IHC staining. Coculture of TAMs and colorectal cancer cells both in vitro and in vivo models was used to evaluate the effects of TAMs on colorectal cancer chemoresistance. Cytokine antibody arrays, ELISA, neutralizing antibody, and luciferase reporter assay were performed to uncover the underlying mechanism.Results: TAM infiltration was associated with chemoresistance in patients with colorectal cancer. Colorectal cancer-conditioned macrophages increased colorectal cancer chemoresistance and reduced drug-induced apoptosis by secreting IL6, which could be blocked by a neutralizing anti-IL6 antibody. Macrophage-derived IL6 activated the IL6R/STAT3 pathway in colorectal cancer cells, and activated STAT3 transcriptionally inhibited the tumor suppressor miR-204-5p. Rescue experiment confirmed that miR-204-5p is a functional target mediating the TAM-induced colorectal cancer chemoresistance. miR-155-5p, a key miRNA regulating C/EBPβ, was frequently downregulated in TAMs, resulting in increased C/EBPβ expression. C/EBPβ transcriptionally activated IL6 in TAMs, and TAM-secreted IL6 then induced chemoresistance by activating the IL6R/STAT3/miR-204-5p pathway in colorectal cancer cells.Conclusions: Our data indicate that the maladjusted miR-155-5p/C/EBPβ/IL6 signaling in TAMs could induce chemoresistance in colorectal cancer cells by regulating the IL6R/STAT3/miR-204-5p axis, revealing a new cross-talk between immune cells and tumor cells in colorectal cancer microenvironment. Clin Cancer Res; 23(23); 7375-87. ©2017 AACR.

Knockdown of lncRNA-XIST enhances the chemosensitivity of NSCLC cells via suppression of autophagy

Drug resistance is the major factor contributing to the failure of chemotherapy in non-small cell lung cancer (NSCLC) patients. Emerging evidence suggests that autophagy plays a vital role in the chemoresistance of many types of tumors. However, the exact mechanism underlying the chemoresistance of NSCLC is still elusive, and it is unclear whether lncRNA-XIST is involved in autophagy and chemoresistance of NSCLC. In the present study, we demonstrated that lncRNA-XIST was overexpressed in NSCLC tumor samples, and knockdown of lncRNA-XIST significantly decreased autophagy by regulation of ATG7 as determined by qPCR and by western blotting. Furthermore, we found that miR-17 was upregulated following knockdown of lncRNA-XIST, and miR-17 mimics decreased the protein levels of ATG7 by directly targeting the 3'-untranslated region of ATG7 mRNA as determined by RT-qPCR and by western blotting. Furthermore, we found that the expression level of lncRNA-XIST was markedly increased in cisplatin-resistant A549 cells as determined by q-PCR. Knockdown of lncRNA-XIST restored the chemosensitivity of cisplatin-resistant A549 cells to cisplatin, which was reversed by miR-17 inhibitor and overexpression of ATG7 as determined by CCK8 assays. This study provides evidence that lncRNA-XIST may be a potential marker of poor response to cisplatin chemotherapy in NSCLC patients and the pathway 'lncRNA-XIST/miR-17/autophagy' may be a promising target for patients with chemoresistant NSCLC.

Long non-coding RNA LINC00152 promotes cell proliferation, metastasis, and confers 5-FU resistance in colorectal cancer by inhibiting miR-139-5p

Long intergenic non-coding RNA 152 (LINC00152) is a recently identified tumor-promoting long non-coding RNA. However, the biological functions of LINC00152 in colorectal cancer (CRC) remain unclear and require further research. The aim of the present study is to explore the roles of LINC00152 in cellular function and its possible molecular mechanism. In this study, we discovered that LINC00152 was overexpressed in CRC tissues and negatively related to the survival time of CRC patients. Functional analyses revealed that LINC00152 could promote cell proliferation. Furthermore, LINC00152 could increase the resistance of CRC cells to 5-fluorouracil (5-FU) by suppressing apoptosis. We also discovered that LINC00152 could enhance cell migration and invasion. Mechanistic studies demonstrated that LINC00152 could regulate the expression of NOTCH1 through sponging miR-139-5p and inhibiting its activity from promoting CRC progression and development. Altogether, our work points out a novel LINC00152/miR-139-5p/NOTCH1 regulatory axis in CRC progression and development.

Comprehensive Profiling of lincRNAs in Lung Adenocarcinoma of Never Smokers Reveals Their Roles in Cancer Development and Prognosis

Long intergenic non-coding RNA (lincRNA) is a family of gene transcripts, the functions of which are largely unknown. Although cigarette smoking is the main cause for lung cancer, lung cancer in non-smokers is a separate entity and its underlying cause is little known. Growing evidence suggests lincRNAs play a significant role in cancer development and progression; however, such data is lacking for lung cancer in non-smokers, or those who have never smoked. This study conducted comprehensive profiling of lincRNAs from RNA sequencing (RNA-seq) data of non-smoker patients with lung adenocarcinoma. Both known and novel lincRNAs distinctly segregated tumors from normal tissues. Approximately one third of lincRNAs were differentially expressed between tumors and normal samples and most of them were coordinated with their putative protein gene targets. More importantly, lincRNAs defined two clusters of tumors that were associated with tumor aggressiveness and patient survival. We identified a subset of lincRNAs that were differentially expressed and also associated with patient survival. Very high concordance (R² = 0.9) was observed for the differentially expressed lincRNAs in the Cancer Genome Atlas (TCGA) validation set of 85 transcriptomes and the lincRNAs associated with survival from the discovery set were similarly predictive in the validation set. These lincRNAs warrant further investigation as potential diagnostic and prognostic markers.

LncRNA UCA1 promotes proliferation and cisplatin resistance of oral squamous cell carcinoma by sunppressing miR-184 expression

Chemotherapy resistance has become the main obstacle for the effective treatment of human cancers. Long non‐coding RNA urothelial cancer associated 1 (UCA1) is generally regarded as an oncogene in some cancers. However, the function and molecular mechanism of UCA1 implicated in cisplatin (CDDP) chemoresistance of oral squamous cell carcinoma (OSCC) is still not fully established. UCA1 expression in tumor tissues and cells was tested by qRT‐PCR. MTT, flow cytometry and caspase‐3 activity analysis were explored to evaluate the CDDP sensitivity in OSCC cells. Western blot analysis was used to measure BCL2, Bax and SF1 protein expression. Luciferase reporter assay was conducted to investigate the molecular relationship between UCA1, miR‐184, and SF1. Nude mice model was used to confirm the functional role of UCA1 in CDDP resistance in vivo. UCA1 expression was upregulated in OSCC tissues, cell lines, and CDDP resistant OSCC cells. Function analysis revealed that UCA1 facilitated proliferation, enhanced CDDP chemoresistance, and suppressed apoptosis in OSCC cells. Mechanisms investigation indicated that UCA1 could interact with miR‐184 to repress its expression. Rescue experiments suggested that downregulation of miR‐184 partly reversed the tumor suppression effect and CDDP chemosensitivity of UCA1 knockdown in CDDP‐resistant OSCC cells. Moreover, UCA1 could perform as a miR‐184 sponge to modulate SF1 expression. The OSCC nude mice model experiments demonstrated that depletion of UCA1 further boosted CDDP‐mediated repression effect on tumor growth. UCA1 accelerated proliferation, increased CDDP chemoresistance and restrained apoptosis partly through modulating SF1 via sponging miR‐184 in OSCC cells, suggesting that targeting UCA1 may be a potential therapeutic strategy for OSCC patients

LncRNAs and their role in cancer stem cells

Cancer stem cells (CSCs) play a vital role in the formation of tumors and have been studied as a target of anticancer therapy. Long non-coding RNAs (lncRNAs) are important in the genesis and progression of cancer. Various lncRNAs, such as ROR, HOTAIR, H19, UCA1, and ARSR, are involved in cancer stemness. These lncRNAs could regulate the expression of CSC-related transcriptional factors, such as SOX2, OCT4, and NANOG, in colorectal, prostate, bladder, breast, liver, and other cancer types. In this work, we review the progress of lncRNAs and cancer stem cells and discuss the potential signal pathways of lncRNAs in cancer stemness.

The protective value of miR-204-5p for prognosis and its potential gene network in various malignancies: a comprehensive exploration based on RNA-seq high-throughput data and bioinformatics

Purpose

The prognostic role of miR-204-5p (previous ID: miR-204) is varied and inconclusive in diverse types of malignant neoplasm. Therefore, the purposes of the study comprehensively explore the overall prognostic role of miR-204-5p based on high-throughput microRNA sequencing data, and to investigate the potential role of miR-204-5p via bioinformatics approaches.

Materials and Methods

The data of microRNA sequencing and survival were downloaded from The Cancer Genome Atlas (TCGA), and the prognostic value of miR-204-5p was analyzed by using Kaplan-Meier and univariate cox regressions. Then a meta-analysis was conducted with all TCGA data and relevant studies collected from literature. Pooled hazard ratios (HRs) with 95% confidence intervals (CIs) were calculated. The prospective molecular mechanism of miR-204-5p was also assessed at a functional level with Gene Ontology (GO), Kyoto Encyclopedia of Genes and Genomes (KEGG), and protein-to-protein interactions (PPI) network.

Results

From TCGA data, the prognostic value of miR-204-5p obviously varied among 20 types of cancers. The pooled HR was 0.928 (95% CI: 0.774-1.113, P = 0.386, 6203 cases of malignancies). For the meta-analysis based on 15 studies from literature, the pooled HR was 0.420 (95% CI: 0.306-0.576, P < 0.001, 1783 cases of malignancies) for overall survival (OS). Furthermore, the combined HR from both TCGA and literature was 0.708 (95% CI: 0.600-0.834, P < 0.001, 7986 cases of malignancies). Subgroup analyses revealed that miR-204-5p could act as a prognostic marker in cancers of respiratory system and digestive system. Functional analysis was conducted on genes predicted as targets (n = 2057) after the overlay genes from six out of twelve software were extracted. Two significant KEGG pathways were enriched (hsa04360: Axon guidance and hsa04722: Neurotrophin signaling pathway). PPI network revealed some hub genes/proteins (CDC42, SOS1, PIK3R1, MAPK1, PLCG1, ESR1, MAPK11, and AR).

Conclusions

The current study demonstrates that over-expression of miR-204-5p could be a protective factor for a certain group of cancers. Clinically, the low miR-204-5p level could gain a predictive value for a poor survival in cancers of respiratory system and digestive system. The detailed molecular mechanisms of miR-204-5p remain to be verified.

Extracellular vesicles as emerging targets in cancer: Recent development from bench to bedside

Extracellular vesicles (EVs) have emerged as important players of cancer initiation and progression through cell-cell communication. They have been recognized as critical mediators of extracellular communications, which promote transformation, growth invasion, and drug-resistance of cancer cells. Interestingly, the secretion and uptake of EVs are regulated in a more controlled manner than previously anticipated. EVs are classified into three groups, (i) exosomes, (ii) microvesicles (MVs), and (iii) apoptotic bodies (ABs), based on their sizes and origins, and novel technologies to isolate and distinguish these EVs are evolving. The biologically functional molecules harbored in these EVs, including nucleic acids, lipids, and proteins, have been shown to induce key signaling pathways in both tumor and tumor microenvironment (TME) cells for exacerbating tumor development. While tumor cell-derived EVs are capable of reprogramming stromal cells to generate a proper tumor cell niche, stromal-derived EVs profoundly affect the growth, resistance, and stem cell properties of tumor cells. This review summarizes and discusses these reciprocal communications through EVs in different types of cancers. Further understanding of the pathophysiological roles of different EVs in tumor progression is expected to lead to the discovery of novel biomarkers in liquid biopsy and development of tumor specific therapeutics. This review will also discuss the translational aspects of EVs and therapeutic opportunities of utilizing EVs in different cancer types.

Long non-coding RNAs: a rising biotarget in colorectal cancer

Colorectal cancer (CRC) is a common gastrointestinal cancer, with a high incidence and high mortality. Long non-coding RNAs (lncRNAs) are involved in the development, invasion and metastasis, early diagnosis, prognosis, the chemoresistance and radioresistance of CRC through interference with mRNA activity, directly combining with proteins to regulate their activity or alter their localization, influencing downstream gene expression by inhibiting RNA polymerase and regulating gene expression as competing endogenous RNAs. Recent progress in next generation sequencing and transcriptome analysis has revealed that tissue and cancer-type specific lncRNAs could be useful prognostic markers. Here, the CRC-associated lncRNAs from recent studies until October 2016 are reviewed and multiple studies that have confirmed CRC-associated lncRNAs are summarized. This review may be helpful in understanding the overall relationships between the lncRNAs involved in CRC.