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.     

Downregulation of miR‐491‐5p promotes gastric cancer metastasis by regulating SNAIL and FGFR4

Gastric cancer (GC) is among the most fatal cancers in China. MicroRNAs (miRNAs) are versatile regulators during GC development and progression. miR‐491‐5p has been demonstrated to act as a tumor suppressor in several types of cancer. However, the role of miR‐491‐5p in GC metastasis remains unknown. Here, we found that miR‐491‐5p was significantly decreased in GC tissues compared with adjacent non‐cancerous tissues, and low miR‐491‐5p level was associated with large tumor size. Overexpression of miR‐491‐5p significantly suppressed GC cell epithelial‐to‐mesenchymal transition (EMT) and tumor metastasis in vitro and in vivo. Mechanistically, SNAIL was identified as a direct target of miR‐491‐5p. The silencing of SNAIL phenocopied the tumor suppressive function of miR‐491‐5p, whereas re‐expression of SNAIL in GC cells rescued the EMT markers and cell migratory ability that were inhibited by miR‐491‐5p. In addition, miR‐491‐5p inhibited FGFR4 indirectly. Inhibition of FGFR4 also decreased the SNAIL level and impaired EMT and cell migration. Taken together, these findings indicate that downregulation of miR‐491‐5p promoted GC metastasis by inducing EMT via regulation of SNAIL and FGFR4.     

Circular RNA hsa_circ_001895 serves as a sponge of microRNA‐296‐5p to promote clear cell renal cell carcinoma progression by regulating SOX12

There is an urgent need to find novel potential therapeutic targets for the diagnosis and treatment of clear cell renal cell carcinoma (ccRCC) due to its highly invasive ability as a common urological malignant tumor. Circular RNAs (circRNAs) have been indicated as potentially critical mediators in various types of tumor progression. We first used qRT‐PCR analysis to find dysregulated circRNAs in ccRCC. A novel circRNA, hsa_circ_001895, was upregulated in ccRCC specimens and associated with metastatic properties of ccRCC. However, the tumorigenic mechanism of hsa_circ_001895 on ccRCC is yet to be found. We first indicated that hsa_circ_001895 predicted a poor prognosis in ccRCC patients. Additionally, overexpression of hsa_circ_001895 not only promoted cell proliferation, invasion and migration of ccRCC, but also inhibited cell apoptosis, whereas hsa_circ_001895 knockdown reversed the effect on ccRCC progression. In vivo s.c. xenotransplanted tumor model also showed that silencing hsa_circ_001895 could suppress in vivo ccRCC growth. Mechanistically, hsa_circ_001895 directly binds with microRNA (miR)‐296‐5p and inhibits its expression. Moreover, sex determining region Y (SRY)‐box 12 (SOX12) was identified as a target of miR‐296‐5p, the expression of which was suppressed by miR‐296‐5p. Notably, the inhibitory effect of hsa_circ_001895 on ccRCC progression was reversed by miR‐296‐5p inhibitor. In general, our findings indicated that hsa_circ_001895 may sponge miR‐296‐5p and promote SOX12 expression, which is the underlying mechanism of hsa_circ_001895‐induced ccRCC progression.     

MicroRNA‐155‐5p promotes hepatocellular carcinoma progression by suppressing PTEN through the PI3K/Akt pathway

MicroRNA‐155‐5p (miR‐155‐5p) has been reported to play an oncogenic role in different human malignancies; however, its role in hepatocellular carcinoma (HCC) progression is not clearly understood. In this study, we used real‐time PCR in 20 rats with chemically‐induced HCC, 28 human HCC tissues, and the matched paracarcinoma tissues, and HCC cell lines to determine the expression patterns of miR‐155‐5p and PTEN mRNA. Algorithm‐based and experimental strategies, such as dual luciferase gene reporter assays, real‐time PCR and western blots were used to identify PTEN as a candidate miR‐155‐5p target. Gain‐ and loss‐of‐function experiments and administration of a PI3K/Akt pathway inhibitor (wortmannin) were used to identify the effects of miR‐155‐5p and PTEN in MTT assays, flow cytometric analysis, wound healing assays and transwell assays. The results showed that miR‐155‐5p was highly overexpressed; however, PTEN was underexpressed in the HCC rat models, human HCC tissues and cell lines. In addition, miR‐155‐5p upregulation and PTEN downregulation were significantly associated with TNM stage (P < 0.05). Through in vitro experiments, we found that miR‐155‐5p promoted proliferation, invasion and migration, but inhibited apoptosis in HCC by directly targeting the 3′‐UTR of PTEN. Western blots showed that miR‐155‐5p inactivated Bax and caspase‐9, but activated Bcl‐2 to inhibit apoptosis, and it activated MMP to promote migration and invasion via the PI3K/Akt pathway. A xenograft tumor model was used to demonstrate that miR‐155‐5p targets PTEN and activates the PI3K/Akt pathway in vivo as well. Our study highlighted the importance of miR‐155‐5p and PTEN associated with aggressive HCC both in vitro and in vivo.     

MicroRNA‐708‐3p mediates metastasis and chemoresistance through inhibition of epithelial‐to‐mesenchymal transition in breast cancer

Metastasis and chemoresistance remain major challenges in the clinical treatment of breast cancer. Recent studies show that dysregulated microRNAs (miRNAs) play an important role in metastasis and chemoresistance development in breast cancer. Herein, we identified downregulated expression of miR‐708‐3p in breast cancers. In particular, miR‐708‐3p expression was significantly decreased in specimens from breast cancer patients with metastasis compared to that in specimens from patients with no metastasis. Consistent with clinical data, our in vitro data show that miR‐708‐3p was more significantly decreased in invasive breast cancer cell lines. In addition, our data show that inhibition of miR‐708‐3p significantly stimulated breast cancer cell metastasis and induced chemoresistance both in vitro and in vivo. In contrast, overexpression of miR‐708‐3p dramatically inhibited breast cancer cell metastasis and enhanced the sensitivity of breast cancer cells to chemotherapy both in vitro and in vivo. Furthermore, we identified that miR‐708‐3p inhibits breast cancer cell epithelial‐to‐mesenchymal transition (EMT) by directly targeting EMT activators, including ZEB1, CDH2 and vimentin. Taken together, our findings suggest that miR‐708‐3p acts as a cancer suppressor miRNA and carries out its anticancer function by inhibiting EMT in breast cancer. In addition, our findings suggest that restoration of miR‐708‐3p may be a novel strategy for inhibiting breast cancer metastasis and overcoming the chemoresistance of breast cancer cells.     

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 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 TUG1 promotes migration and invasion by acting as a ceRNA of miR‐335‐5p in osteosarcoma cells

Long non‐coding RNA (lncRNA) have been the focus of increasing attention due to the role they play in many diseases, including osteosarcoma. The function of taurine upregulated gene 1 (TUG1) and its mechanism in osteosarcoma remain unclear. In our research, we found that TUG1 was elevated and correlated with a poor prognosis in osteosarcoma patients. In addition, the following functional experiment showed that decreased TUG1 could remarkably inhibit osteosarcoma cell migration and invasion, indicating that TUG1 functioned as an oncogene in osteosarcoma. Moreover, we revealed that TUG1 and Rho‐associated coiled‐coil‐containing protein kinase 1 (ROCK1), a metastasis‐related gene targeted by microRNA‐335‐5p (miR‐335‐5p), had the same miR‐335‐5p combining site. The subsequent luciferase assay verified TUG1 was a target of miR‐335‐5p. Furthermore, the results of a real‐time quantitative PCR showed that TUG1 and miR‐335‐5p could affect each other's expression. respectively. Finally, we affirmed that TUG1 affected ROCK1 expression and ROCK1‐mediated migration/invasion by working as a competitive endogenous RNA (ceRNA) via miR‐335‐5p. In summary, the findings of this study, based on ceRNA theory, combining the research foundation of miR‐335‐5p and ROCK1, and taking TUG1 as a new study point, provide new insight into molecular‐level reversing migration and invasion of osteosarcoma.     

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.     

PVT1‐derived miR‐1207‐5p promotes breast cancer cell growth by targeting STAT6

Accumulating evidence indicates that ectopic expression of non‐coding RNAs are responsible for breast cancer progression. Increased non‐coding RNA PVT1, the host gene of microRNA‐1207‐5p (miR‐1207‐5p), has been associated with breast cancer proliferation. However, how PVT1 functions in breast cancer is still not clear. In this study, we show a PVT1‐derived microRNA, miR‐1207‐5p, that promotes the proliferation of breast cancer cells by directly regulating STAT6. We first confirm the positive correlated expression pattern between PVT1 and miR‐1207‐5p by observing consistent induced expression by estrogen, and overexpression in breast cancer cell lines and breast cancer patient specimens. Moreover, silence of PVT1 also decreased miR‐1207‐5p expression. Furthermore, increased miR‐1207‐5p expression promoted, while decreased miR‐1207‐5p expression suppressed, cell proliferation, colony formation, and cell cycle progression in breast cancer cell lines. Mechanistically, a novel target of miR‐1207‐5p, STAT6, was identified by a luciferase reporter assay. Overexpression of miR‐1207‐5p decreased the levels of STAT6, which activated CDKN1A and CDKN1B to regulate the cell cycle. We also confirmed the reverse correlation of miR‐1207‐5p and STAT6 expression levels in breast cancer samples. Therefore, our findings reveal that PVT1‐derived miR‐1207‐5p promotes the proliferation of breast cancer cells by targeting STAT6, which in turn controls CDKN1A and CDKN1B expression. These findings suggest miR‐1207‐5p might be a potential target for breast cancer therapy.     

MiR‐1285‐5p/TMEM194A axis affects cell proliferation in breast cancer

The onset of breast cancer among young patients is a major issue in cancer etiology. Our previous study has shown that poor prognosis in young women with breast cancer is associated with lower expression of the microRNA miR‐1285‐5p. In this study, we showed that the expression of miR‐1285‐5p is lower in tumor tissues than in normal tissues. Accumulating evidence suggests that miR‐1285‐5p plays critical roles in various types of cancers. However, the functional role of miR‐1285‐5p in breast cancer remains to be elucidated. Here, we showed the tumor‐suppressive role of miR‐1285‐5p and detailed its mechanism of action in breast cancer. Overexpression of miR‐1285‐5p significantly inhibited cell proliferation in breast cancer cells regardless of the tumor subtype. Among the target genes of miR‐1285‐5p, we found that transmembrane protein 194A (TMEM194A) was directly regulated by miR‐1285‐5p. Notably, separation of centrosomes from the nuclear envelope was observed upon knockdown of TMEM194A or overexpression of miR‐1285‐5p. In conclusion, our findings show that miR‐1285‐5p is a tumor suppressor via TMEM194A inhibition in breast cancer.     

Silencing circular RNA UVRAG inhibits bladder cancer growth and metastasis by targeting the microRNA‐223/fibroblast growth factor receptor 2 axis

Circular RNA UVRAG (circUVRAG), a type of non‐coding RNA, is derived and cyclized by part of the exon from the UVRAG gene. However, the role of circUVRAG in bladder cancer (BLCA) has not been reported. The purpose of the present study was therefore to characterize the role of circUVRAG in BLCA. Bioinformatics analysis showed interactive relationships among circUVRAG, microRNA‐223 (miR‐223), and fibroblast growth factor receptor 2 (FGFR2). Quantitative real‐time PCR was used to detect the expression of circUVRAG in BLCA cell lines. UM‐UC‐3 cells were stably transfected with siRNA against circUVRAG, and cell proliferation and migration ability were tested using the CCK8 assay, clone formation, and Transwell assays in vitro. Tumor xenograft formation and metastasis were determined using nude mice. Fluorescence in situ hybridization was used to confirm the subcellular localization of circUVRAG, and the luciferase reporter assay was used to confirm the relationships among circUVRAG, miR‐223, and FGFR2. Results showed that circUVRAG was upregulated in BLCA cell lines. Downregulation of circUVRAG expression suppressed proliferation and metastasis both in vitro and in vivo. Downregulation of circUVRAG suppressed FGFR2 expression by “sponging” miR‐223, which was confirmed by rescue experiments and luciferase reporter assay. Overall, the results showed that downregulation of circUVRAG suppressed the aggressive biological phenotype of BLCA. Taken together, silencing circular RNA UVRAG inhibited bladder cancer growth and metastasis by targeting the miR‐223/FGFR2 axis, which may provide a potential biomarker and therapeutic target for the management of BLCA.     

Long noncoding‐RNA component of mitochondrial RNA processing endoribonuclease is involved in the progression of cholangiocarcinoma by regulating microRNA‐217

Cholangiocarcinoma (CCA) is a malignant tumor originating from bile duct epithelium and its incidence is increasing year by year. In recent years, long noncoding RNAs (lncRNAs) have been found to play an important role in the occurrence and progression of malignant tumors. In the present study, for the first time, abnormal expression of lnc‐RNA component of mitochondrial RNA processing endoribonuclease (RMRP) and its possible role in CCA were found. We explored the effects of RMRP on various behaviors of CCA cells in vitro and in vivo. In addition, by second‐generation sequencing, we explored the microRNA expression profiles that RMRP may affect in the HCCC‐9810 cell line. We also validated and explored the role of microRNA‐217 (miR‐217) with high differential expression by in vitro experiments. Our findings indicated that RMRP can play a part in promoting cancer by regulating the expression of miR‐217. RMRP is involved in the progression of CCA and can be a novel indicator of poor prognosis in patients with CCA.     

Long non‐coding RNA ROR promotes proliferation,migration and chemoresistance of nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is one of the most common malignancies of the head and neck. It arises from the nasopharynx epithelium and is associated with high morbidity and mortality. Long non‐coding RNA (lncRNA) have been reported to regulate gene interaction and play critical roles in carcinogenesis and progression. LncRNA‐ROR, a recently identified lncRNA, has been shown to be involved in initiation, progression and metastasis of several tumors, including hepatocellular carcinoma, breast cancer and glioma. However, whether lncRNA‐ROR is associated with the progression of NPC remains unknown. Resistance to radiotherapy and chemotherapy is the primary cause of NPC patients’ death. In this study, we found that lncRNA‐ROR was significantly upregulated in NPC tissues compared with normal tissues. Next, our study proved that lncRNA‐ROR was highly associated with the proliferation, metastasis and apoptosis of NPC. The enrichment of lncRNA‐ROR played a critucal functional role in chemoresistance. The mechanism by which NPC resists chemotherapy might be that lncRNA‐ROR suppress p53 signal pathway. Taken together, these data suggested that lncRNA‐ROR played an important role in the progression of NPC; thereby it might become a therapeutic target and reduce chemoresistance for NPC.     

Micro‐RNA‐21 regulates TGF‐β‐induced myofibroblast differentiation by targeting PDCD4 in tumor‐stroma interaction

Transforming growth factor‐β1 (TGF‐β1) induces stromal fibroblast‐to‐myofibroblast transdifferentiation in the tumor‐stroma interactive microenvironment via modulation of multiple phenotypic and functional genes, which plays a critical role in tumor progression. Up to now, the involvement of micro‐RNAs (miRNAs) and their roles in TGF‐β1‐induced myofibroblast differentiation in tumor‐stroma interaction are unclear. Using quantitative real‐time RT‐PCR, we demonstrated that the expression of micro‐RNA‐21 (miR‐21) was upregulated in activated fibroblasts after treatment with TGF‐β1 or conditioned medium from cancer cells. To determine the potential roles of miR‐21 in TGF‐β1‐mediated gene regulation during myofibroblast conversion, we showed that miR‐21 expression was downregulated by miR‐21 inhibitor and upregulated by miR‐21 mimic. Interestingly, downregulation of miR‐21 with the inhibitor effectively inhibited TGF‐β1‐induced myofibroblast differentiation while upregulation of miR‐21 with a mimic significantly promoted myofibroblast differentiation. We further demonstrated that MiR‐21 directly targeted and downregulated programmed cell death 4 (PDCD4) gene, which in turn acted as a negative regulator of several phenotypic and functional genes of myofibroblasts. Taken together, these results suggested that miR‐21 participated in TGF‐β1‐induced myofibroblast transdifferentiation in cancer stroma by targeting PDCD4.