Long noncoding RNA actin filament‐associated protein 1 antisense RNA 1 promotes malignant phenotype through binding with lysine‐specific demethylase 1 and repressing HMG box‐containing protein 1 in non‐small‐cell lung cancer

The number of documented long noncoding RNAs (lncRNAs) has dramatically increased, and their biological functions and underlying mechanisms in pathological processes, especially cancer, remain to be elucidated. Actin filament‐associated protein 1 antisense RNA 1 (AFAP1‐AS1) is a 6810‐nt lncRNA located on chromosome 4p16.1 that was first reported to be upregulated in esophageal adenocarcinoma tissues and cell lines. Here we reported that AFAP1‐AS1, recruiting and binding to lysine‐specific demethylase 1 (LSD1), was generally overexpressed in human non‐small‐cell lung cancer (NSCLC) tissues using quantitative real‐time PCR. Higher AFAP1‐AS1 expression was significantly correlated with larger tumor size (P = .008), lymph node metastasis (P = .025), higher TNM stage (P = .024), and worse overall survival in NSCLC patients. In vitro experiments revealed that AFAP1‐AS1 downregulation inhibited cell migration and induced apoptosis; AFAP1‐AS1 knockdown also hindered tumorigenesis in vivo. Moreover, mechanistic investigations including RNA immunoprecipitation and ChIP assays validated that AFAP1‐AS1 repressed HMG box‐containing protein 1 (HBP1) expression by recruiting LSD1 to the HBP1 promoter regions in PC‐9 and H1975 cells. Furthermore, HBP1 functions as a tumor suppressor, and its ectopic expression hindered cell proliferation. Rescue assays determined that the oncogenic effect of AFAP1‐AS1 is partially dependent on the epigenetic silencing of HBP1. In conclusion, our results indicate that AFAP1‐AS1 is carcinogenic and that the AFAP1‐AS1/LSD1/HBP1 axis could constitute a new therapeutic direction for NSCLC.     

Long non‐coding RNA urothelial cancer‐associated 1 promotes bladder cancer cell migration and invasion by way of the hsa‐miR‐145–ZEB1/2–FSCN1 pathway

Numerous studies suggest that several long non‐coding RNAs (lncRNAs) play critical roles in bladder cancer development and progression. Long non‐coding RNA urothelial cancer‐associated 1 (lncRNA‐UCA1) is highly expressed in bladder cancer tissues and cells, and it has been shown to play an important role in regulating aggressive phenotypes of bladder cancer cells. However, little is known about the molecular mechanism of lncRNA‐UCA1‐mediated bladder cancer cell migration and invasion. Here, we show that overexpression of lncRNA‐UCA1 could induce EMT and increase the migratory and invasive abilities of bladder cancer cells. Mechanistically, lncRNA‐UCA1 induced EMT of bladder cancer cells by upregulating the expression levels of zinc finger E‐box binding homeobox 1 and 2 (ZEB1 and ZEB2), and regulated bladder cancer cell migration and invasion by tumor suppressive hsa‐miR‐145 and its target gene the actin‐binding protein fascin homologue 1 (FSCN1). Furthermore, we also observed a positive correlation between lncRNA‐UCA1 and ZEB1/2 expression, and a negative correlation between lncRNA‐UCA1 and hsa‐miR‐145 expression in bladder cancer specimens. Importantly, we found that lncRNA‐UCA1 repressed hsa‐miR‐145 expression to upregulate ZEB1/2, whereas the suppression of hsa‐miR‐145 could upregulate lncRNA‐UCA1 expression in bladder cancer cells. Moreover, the binding site for hsa‐miR‐145 within exons 2 and 3 of lncRNA‐UCA1 contributed to the reciprocal negative regulation of lncRNA‐UCA1 and hsa‐miR‐145. Taken together, our results identified that lncRNA‐UCA1 enhances bladder cancer cell migration and invasion in part through the hsa‐miR‐145/ZEB1/2/FSCN1 pathway. Therefore, lncRNA‐UCA1 might act as a promising therapeutic target for the invasion and metastasis of bladder cancer.     

Long noncoding RNA MAPKAPK5‐AS1 promotes colorectal cancer proliferation by partly silencing p21 expression

Colorectal cancer (CRC) is the third most common malignancy in the world, and long noncoding RNA (lncRNA) plays a critical role in carcinogenesis. Here, we report a novel lncRNA, MAPKAPK5‐AS1, that acts as a critical oncogene in CRC. In addition, we attempted to explore the functions of MAPKAPK5‐AS1 on tumor progression in vitro and in vivo. Quantitative RT‐PCR was used to examine the expression of MAPKAPK5‐AS1 in CRC tissues and cells. Expression of MAPKAPK5‐AS1 was significantly upregulated in 50 CRC tissues, and increased expression of MAPKAPK5‐AS1 was found to be associated with greater tumor size and advanced pathological stage in CRC patients. Knockdown of MAPKAPK5‐AS1 significantly inhibited proliferation and caused apoptosis in CRC cells. We also found that p21 is a target of MAPKAPK5‐AS1. In addition, we are the first to report that MAPKAPK5‐AS1 plays a carcinogenic role in CRC. MAPKAPK5‐AS1 is a novel prognostic biomarker and a potential therapeutic candidate for CRC cancer.     

Silencing of DLEU2 suppresses pancreatic cancer cell proliferation and invasion by upregulating microRNA‐455

Long noncoding RNA (lncRNA) DLEU2 has been shown to be dysregulated in several type of tumor. However, the potential biological roles and molecular mechanisms of DLEU2 in pancreatic cancer (PC) progression are poorly understood. In this study, we found that the DLEU2 level was substantially upregulated in PC tissues and PC cell lines, and significantly associated with poor clinical outcomes in PC patients. Overexpression of DLEU2 significantly induced PC cell proliferation and invasion, whereas knockdown of DLEU2 impaired cell proliferation and invasion in vitro. Furthermore, bioinformatics analysis, luciferase reporter assay, and RNA immunoprecipitation assay revealed that DLEU2 directly bond to microRNA‐455 (miR‐455) and functioned as an endogenous sponge for miR‐455, which could remarkably suppress cell growth and invasion. We also determined that SMAD2 was a direct target of miR‐455, and the restoration of SMAD2 rescued cell growth and invasion that were reduced by DLEU2 knockdown or miR‐455 overexpression. In addition, low miR‐455 expression and high SMAD2 expression was correlated with poor patient survival. These results indicate that DLEU2 is an important promoter of PC development, and targeting the DLEU2/miR‐455/SMAD2 pathway could be a promising therapeutic approach in the treatment of PC.     

LncRNA DANCR promotes tumor growth and angiogenesis in ovarian cancer through direct targeting of miR‐145

Differentiation antagonizing non‐protein coding RNA (DANCR) is a newly identified oncogenic long noncoding RNA found in various cancers. However, the functional role of DANCR in tumor angiogenesis and the underlying mechanisms are still unclear. The expression of DANCR was determined in ovarian malignant tissues and cell lines. The functional role of DANCR in tumor angiogenesis was revealed by the following methods: CD31 staining of ovarian tumor tissues, matrigel‐plug assay tissues, HUVEC‐related tube formation assay, and invasion assay. Enzyme‐linked immunosorbent assay, Western blotting, luciferase assay, and rescue experiments were used to investigate the underlying mechanisms of DANCR‐regulating angiogenesis. DANCR was upregulated in ovarian malignant tissues and ovarian cancer cells. Knockdown of DANCR efficiently impaired ovarian tumor growth through inhibition of tumor angiogenesis. Furthermore, the conditional culture medium from DANCR‐knockdown ovarian cells significantly inhibited tube formation and invasion of HUVEC in vitro. Mechanistic investigation indicated that vascular endothelial growth factor A (VEGF‐A, VEGF) plays a crucial role during DANCR inhibition of tumor angiogenesis in ovarian cancer. Further results demonstrated that miR‐145 is the direct binding target of DANCR during regulation of VEGF expression and tumor angiogenesis in ovarian cancer cells. Collectively, DANCR plays a promotional role in tumor angiogenesis in ovarian cancer through regulation of miR‐145/VEGF axis. Therefore, DANCR may be a novel therapy target for ovarian cancer.     

MicroRNA‐16 inhibits glioma cell growth and invasion through suppression of BCL2 and the nuclear factor‐κB1/MMP9 signaling pathway

Recent studies have identified a class of small non‐coding RNA molecules, named microRNA (miRNA), that is dysregulated in malignant brain glioblastoma. Substantial data have indicated that miRNA‐16 (miR‐16) plays a significant role in tumors of various origins. This miRNA has been linked to various aspects of carcinogenesis, including cell apoptosis and migration. However, the molecular functions of miR‐16 in gliomagenesis are largely unknown. We have shown that the expression of miR‐16 in human brain glioma tissues was lower than in non‐cancerous brain tissues, and that the expression of miR‐16 decreased with increasing degrees of malignancy. Our data suggest that the expression of miR‐16 and nuclear factor (NF)‐κB1 was negatively correlated with glioma levels. MicroRNA‐16 decreased glioma malignancy by downregulating NF‐κB1 and MMP9, and led to suppressed invasiveness of human glioma cell lines SHG44, U87, and U373. Our results also indicated that upregulation of miR‐16 promoted apoptosis by suppressing BCL2 expression. Finally, the upregulation of miR‐16 in a nude mice model of human glioma resulted in significant suppression of glioma growth and invasiveness. Taken together, our experiments have validated the important role of miR‐16 as a tumor suppressor gene in glioma growth and invasiveness, and revealed a novel mechanism of miR‐16‐mediated regulation in glioma growth and invasiveness through inhibition of BCL2 and the NF‐κB1/MMP‐9 signaling pathway. Therefore, our experiments suggest the possible future use of miR‐16 as a therapeutic target in gliomas.     

Long noncoding RNA TP53TG1 promotes pancreatic ductal adenocarcinoma development by acting as a molecular sponge of microRNA‐96

Long noncoding RNAs (lncRNAs) are emerging as key regulators in cancer initiation and progression. TP53TG1 is a recently identified lncRNA and several studies have shown that TP53TG1 may play the role of tumor suppressor gene or oncogene in different tumors. Nevertheless, the involvement of TP53TG1 in carcinogenesis of pancreatic ductal adenocarcinoma (PDAC) has not been characterized. In our studies, we identified that TP53TG1 was highly expressed in PDAC and was a novel regulator of PDAC development. Knockdown of TP53TG1 inhibited proliferation, induced apoptosis, and decreased migration and invasion in PDAC cells, whereas enhanced expression of TP53TG1 had the opposite effects. Mechanistically, TP53TG1 could directly bind to microRNA (miR)‐96 and effectively function as a sponge for miR‐96, thus antagonizing the functions of miR‐96 and leading to derepression of its endogenous target KRAS, which is a core oncogene in the initiation and maintenance of PDAC. Taken together, these observations imply that TP53TG1 contributes to the growth and progression of PDAC by acting as a competing endogenous RNA (ceRNA) to competitively bind to miR‐96 and regulate KRAS expression, which highlights the importance of the complicated miRNA‐lncRNA network in modulating the progression of PDAC.     

DANCR‐mediated microRNA‐665 regulates proliferation and metastasis of cervical cancer through the ERK/SMAD pathway

Emerging evidence has indicated that microRNAs (miRNAs) play an important role in cervical cancer (CC). However, the role of miRNA (miR)‐665 in cervical cancer remains unclear. The aim of the present study was to investigate the potential functions of miR‐665 in CC and to identify the underlying mechanisms of action. Herein, we show that miR‐665 was downregulated in CC tissues and cell lines, which is negatively correlated with tumor size, distant metastasis, advanced TNM stage and poor prognosis. Functionally, miR‐665 inhibited cell proliferation, migration and invasion and resistance of cisplatin for CC cells, as well as tumor growth. We validated that transforming growth factor beta receptor 1 (TGFBR1) was a direct target of miR‐665 and mediated the ERK/SMAD pathway. In addition, we identified miR‐665 as the competing endogenous RNA for long noncoding (lnc)‐DANCR. These observations suggested that lnc‐DANCR‐mediated miR‐665 downregulation regulates the malignant phenotype of CC cells by targeting TGFBR1 through the ERK/SMAD pathway, which may present a pathway for novel therapeutic stratagems for CC therapy.     

The encouraging role of long noncoding RNA small nuclear RNA host gene 16 in epithelial‐mesenchymal transition of bladder cancer via directly acting on miR‐17‐5p/metalloproteinases 3 axis

The present investigation was intended to elucidate whether long noncoding RNA small nuclear RNA host gene 16 (SNHG16) could regulate the epithelial‐mesenchymal transition process of bladder cancer cells by directing expressions of miR‐17‐5p and metalloproteinases 3 (TIMP3). To elucidate the point, we collected 275 pairs of bladder cancer tissues and corresponding adjacent normal tissues, as well as four bladder cancer cell lines and the normal human bladder epithelial cell line. Moreover, pcDNA3.1‐SNHG16, si‐SNHG16, miR‐17‐5p mimic, miR‐17‐5p inhibitor, pcDNA3.1‐TIMP3, and si‐TIMP3 were prepared for transfection, and CCK‐8 assay, colony formation assay, flow cytometry, wound healing assay, and transwell assay were carried out. Finally, the dual luciferase reporter gene assay was performed to figure out whether targeted regulations were present among SNHG16, miR‐17‐5p, and TIMP3. The laboratory findings demonstrated that the bladder cancer patients carrying under‐expressed SNHG16 or miR‐17‐5p were associated with extended survival time when compared with those possessing overexpressed SNHG16 and miR‐17‐5p (P < 0.05). Furthermore, overexpression of SNHG16 and miR‐17‐5p both enhanced the viability, proliferation, migration, and invasion (P < 0.05), and simultaneously suppressed their apoptosis (P < 0.05). Transfections of pcDNA3.1‐SNHG16 and si‐SNHG16, respectively, resulted in overexpression and under‐expression of miR‐17‐5p, and the dual luciferase reporter gene assay demonstrated a targeted relationship between SNHG16 and miR‐17‐5p (P < 0.05). Besides, the expression of TIMP3 was subjected to targeted regulation of miR‐17‐5p (P < 0.05), and its overexpression could reverse the effects of miR‐17‐5p on proliferation and metastasis (P < 0.05). Conclusively, purposeful modification of SNHG16/miR‐17‐5p/TIMP3 signaling might be conducive to postpone the aggravation of bladder cancer.     

Long non‐coding RNA Fer‐1‐like protein 4 suppresses oncogenesis and exhibits prognostic value by associating with miR‐106a‐5p in colon cancer

Novel long non‐coding RNA Fer‐1‐like protein 4 (FER1L4) has been confirmed to play crucial regulatory roles in tumor progression. It exerts an impact on tumor suppression and functions as a competing endogenous RNA (ceRNA) by sponging miR‐106a‐5p in gastric cancer. However, its clinical significance in colon cancer is completely unknown. The aim of the present study was to annotate the role of FER1L4 and its clinical value in colon cancer. The results showed the aberrant expression of FER1L4 and miR‐106a‐5p in colon cancer tissues. In addition, significant negative correlation between FER1L4 and miR‐106a‐5p expression levels was observed. Among the colon cancer cell lines, FER1L4 levels were relatively lower, with concurrent high levels of miR‐106a‐5p. Restoration of FER1L4 decreased the expression of miR‐106a‐5p, and had a significant influence on colon cancer cell proliferation, migration and invasion. The FER1L4 expression was correlated with depth of tumor invasion, lymph node metastasis, vascular invasion and clinical stage. Moreover, striking differences in overall survival and disease‐free survival were observed for the cases with both low FER1L4 expression and high miR‐106a‐5p expression compared with cases with high FER1L4 expression and low miR‐106a‐5p expression. Circulating FER1L4 and miR‐106a‐5p levels were decreased and increased, respectively, in colon cancer patients after surgery. Our findings indicated that FER1L4 could exert a tumor suppressive impact on colon cancer, which at least, in part, through suppressing miR‐106a‐5p expression, and depletion of FER1L4, alone or combined with overexpression of miR‐106a‐5p, is predictive of poor prognosis in colon cancer and may play a crucial role in cancer prevention and treatment.