The lncRNA FEZF1-AS1 Promotes the Progression of Colorectal Cancer Through Regulating OTX1 and Targeting miR-30a-5p

Long noncoding RNAs (lncRNAs) participate in and regulate the biological process of colorectal cancer (CRC) progression. Our previous research identified differentially expressed lncRNAs in 10 CRC tissues and 10 matched nontumor tissues by next-generation sequencing (NGS). In this study, we identified an lncRNA, FEZF1 antisense RNA 1 (FEZF1-AS1), and further explored its function and mechanism in CRC. We verified that FEZF1-AS1 is highly expressed in CRC tissues and cell lines. Through functional experiments, we found that reduced levels of FEZF1-AS1 significantly suppressed CRC cell migration, invasion, and proliferation and inhibited tumor growth in vivo. Mechanistically, we discovered that reduced levels of the lncRNA FEZF1- AS1 inhibited the activation of epithelial–mesenchymal transition (EMT); the overexpression of orthodenticle homeobox 1 (OTX1) partially rescued the FEZF1-AS1-induced inhibition of protein expression. It indicated that FEZF1-AS1 may play a role in the occurrence and development of CRC by regulating the FEZF1-AS1/ OTX1/EMT pathway. Furthermore, it was reported that FEZF1-AS1 is located in both the nucleus and cytoplasm of HCT116 cells. Dual-luciferase reporter assays verified that FEZF1-AS1 directly binds miR-30a-5p and negatively regulated each other. Further, we showed that 5 -nucleotidase ecto (NT5E) is a direct target of miR-30a-5p, and the inhibition of miR-30a-5p expression partially rescued the inhibitory effect of FEZF1-AS1 on NT5E. Our results indicated that the mechanism by which FEZF1-AS1 positively regulates the expression of NT5E is through sponging miR-30a-5p. Our study demonstrated that lncRNA FEZF1-AS1 is involved in the development of CRC and may serve as a diagnostic and therapeutic target for CRC patients.     

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.     

MicroRNA-31 contributes to colorectal cancer development by targeting factor inhibiting HIF-1α (FIH-1)

The molecular mechanisms underlying colorectal cancer (CRC) tumorigenesis remain incompletely understood, partially contributing to the mortality of CRC. Advances in identification of novel mechanisms are therefore in an urgent need to fill the gap of our knowledge in CRC development. Here, we performed both in vitro and in vivo experiments along with in silico analysis to identify a new regulatory circuit that stimulated CRC tumorigenesis. In this report, we, for the first time, analyzed the correlation of FIH-1 level with clinicopathological features of CRC. The finding that FIH-1 was not only significantly decreased in tumor tissue as compared with the adjacent normal tissue but also was significantly correlated with tumor T stage status, indicated the role of FIH-1 as a tumor suppressor in CRC development. Moreover, we found the expression of miR-31, a short non-coding RNA which played a critical role in CRC development, was negatively correlated with FIH-1 expression in CRC samples and cell lines. Together with the result from luciferase report assay, it was demonstrated that miR-31 could directly regulate FIH-1 expression in CRC. This miR-31/FIH-1 nexus was further shown to control cell proliferation, migration and invasion in vitro and to control tumor growth in vivo. Additionally, correlation of the miR-31 expression with clinicopathologic features in CRC samples was examined in support of the driving role of newly identified miR-31/FIH-1 nexus in CRC tumorigenesis. These findings highlight the critical role of miR-31/FIH-1 nexus in CRC and reveal the contribution of miR-31 to CRC development by targeting FIH-1.     

G protein‐coupled receptor GPR55 promotes colorectal cancer and has opposing effects to cannabinoid receptor 1

The putative cannabinoid receptor GPR55 has been shown to play a tumor‐promoting role in various cancers, and is involved in many physiological and pathological processes of the gastrointestinal (GI) tract. While the cannabinoid receptor 1 (CB₁) has been reported to suppress intestinal tumor growth, the role of GPR55 in the development of GI cancers is unclear. We, therefore, aimed at elucidating the role of GPR55 in colorectal cancer (CRC), the third most common cancer worldwide. Using azoxymethane (AOM)‐ and dextran sulfate sodium (DSS)‐driven CRC mouse models, we found that GPR55 plays a tumor‐promoting role that involves alterations of leukocyte populations, i.e. myeloid‐derived suppressor cells and T lymphocytes, within the tumor tissues. Concomitantly, expression levels of COX‐2 and STAT3 were reduced in tumor tissue of GPR55 knockout mice, indicating reduced presence of tumor‐promoting factors. By employing the experimental CRC models to CB₁ knockout and CB₁/GPR55 double knockout mice, we can further show that GPR55 plays an opposing role to CB₁. We report that GPR55 and CB₁ mRNA expression are differentially regulated in the experimental models and in a cohort of 86 CRC patients. Epigenetic methylation of CNR1 and GPR55 was also differentially regulated in human CRC tissue compared to control samples. Collectively, our data suggest that GPR55 and CB₁ play differential roles in colon carcinogenesis where the former seems to act as oncogene and the latter as tumor suppressor.     

microRNA‐219‐5p inhibits epithelial‐mesenchymal transition and metastasis of colorectal cancer by targeting lymphoid enhancer‐binding factor 1

Aberrant expression of microRNAs (miRs) has been shown to play a critical role in the pathogenesis and progression of tumors. microRNA‐219‐5p (miR‐219‐5p) has been reported to be abnormally expressed in some types of human tumors. However, the mechanism between miR‐219‐5p and colorectal cancer (CRC) metastasis remains unclear. In the present study, miR‐219‐5p was found to be downregulated in CRC tissue compared with matched normal tissue. Through luciferase reporter assay, we demonstrated lymphoid enhancer‐binding factor 1 (LEF1) as a direct target of miR‐219‐5p. Overexpression of miR‐219‐5p could inhibit motility, migration and invasion of CRC cells, and inhibit epithelial‐mesenchymal transition (EMT). Furthermore, silencing LEF1 phenocopied this metastasis‐suppressive function. The recovery experiment showed that re‐expression of LEF1 rescued this suppressive effect on tumor metastasis and reversed the expression of EMT markers caused by miR‐219‐5p. Additionally, we demonstrated that miR‐219‐5p exerted this tumor‐suppressive function by blocking activation of the AKT and ERK pathways. Finally, a nude mice experiment showed that miR‐219‐5p reduced the lung metastasis ability of CRC cells. Taken together, our findings indicate that miR‐219‐5p inhibits metastasis and EMT of CRC by targeting LEF1 and suppressing the AKT and ERK pathways, which may provide a new antitumor strategy to delay CRC metastasis.     

Microarray Analysis of Long Non-coding RNA Expression Profile Associated with 5-Fluorouracil-Based Chemoradiation Resistance in Colorectal Cancer Cells

Background: Preoperative 5-fluorouracil (5-FU)-based chemoradiotherapy is a standard treatment for locallyadvanced colorectal cancer (CRC). However, CRC cells often develop chemoradiation resistance (CRR). Recentstudies have shown that long non-coding RNA (lncRNA) plays critical roles in a myriad of biological processesand human diseases, as well as chemotherapy resistance. Since the roles of lncRNAs in 5-FU-based CRR inhuman CRC cells remain unknown, they were investigated in this study. Materials and Methods: A 5-FU-basedconcurrent CRR cell model was established using human CRC cell line HCT116. Microarray expression profilingof lncRNAs and mRNAs was undertaken in parental HCT116 and 5-FU-based CRR cell lines. Results: In total,2,662 differentially expressed lncRNAs and 2,398 mRNAs were identified in 5-FU-based CRR HCT116 cellswhen compared with those in parental HCT116. Moreover, 6 lncRNAs and 6 mRNAs found to be differentiallyexpressed were validated by quantitative real time PCR (qRT-PCR). Kyoto Encyclopedia of Genes and Genomes(KEGG) pathway analysis for the differentially expressed mRNAs indicated involvement of many, such as Jak-STAT, PI3K-Akt and NF-kappa B signaling pathways. To better understand the molecular basis of 5-FU-basedCRR in CRC cells, correlated expression networks were constructed based on 8 intergenic lncRNAs and theirnearby coding genes. Conclusions: Changes in lncRNA expression are involved in 5-FU-based CRR in CRCcells. These findings may provide novel insight for the prognosis and prediction of response to therapy in CRCpatients.     

Long Noncoding RNA PlncRNA-1 Promotes Colorectal Cancer Cell Progression by Regulating the PI3K/Akt Signaling Pathway

Accumulating evidence has indicated that long noncoding RNA (lncRNA) PlncRNA-1 plays an important regulatory role in cancers. However, the expression and biological functions of PlncRNA-1 in colorectal cancer (CRC) are still unclear. In the present study, we determined the expression of PlncRNA-1 in CRC and explored the function of PlncRNA-1 on CRC cell progression. The results showed that PlncRNA-1 was significantly increased in CRC tissues and cell lines; high PlncRNA-1 expression was associated with depth of invasion, lymph node metastasis, and TNM stage of CRC patients. Kaplan–Meier curve analysis showed that patients with high PlncRNA-1 expression had a poor overall survival. PlncRNA-1 knockdown remarkably reduced cell proliferation, migration, and invasion and promoted cell apoptosis in vitro. In vivo xenograft experiments showed that PlncRNA-1 inhibition significantly suppressed tumor growth. Finally, we used an agonist (740Y-P) of the PI3K/Akt signaling pathway; function assays showed that PlncRNA-1 exerted its effects by targeting the PI3K/Akt signaling pathway in CRC. Taken together, our data suggested that PlncRNA-1 might act as an oncogene in CRC progression and serve as a potential biomarker and therapeutic target for the treatment of CRC.     

卵巢癌肿瘤微环境中长链非编码RNA的研究进展

卵巢癌是死亡率最高的妇科恶性肿瘤,其微环境是由多种细胞和非细胞成分共同组成的。肿瘤细胞和微环境的相互作用影响肿瘤的进展。因此,寻找新的肿瘤标志物及治疗靶点有着重要意义。长链非编码RNA（long non-coding RNA,lncRNA）是长度超过200个核苷酸的非编码RNA,在多种肿瘤的发生、发展和耐药中发挥着重要的作用。在本篇综述中,研究证明lncRNA在卵巢癌肿瘤微环境中细胞成分和非细胞成分交流的过程中发挥重要作用。此外,本文总结了以lncRNA作为靶向卵巢癌肿瘤微环境或细胞成分潜在靶点的治疗方式。