Long non-coding RNA AFAP1-AS1 facilitates tumor growth and promotes metastasis in colorectal cancer

Diagnostics and Therapy for Malignant Tumors

Malignant tumors remain one of the most significant global health challenges and contribute to high mortality rates across various cancer types. The complex nature of these tumors requires multifaceted diagnostic and therapeutic approaches. This review explores current advancements in diagnostic methods, including molecular imaging, biomarkers, and liquid biopsies. It also delves into the evolution of therapeutic strategies, including surgery, chemotherapy, radiation therapy, and novel targeted therapies such as immunotherapy and gene therapy. Although significant progress has been made in the understanding of cancer biology, the future of oncology lies in the integration of precision medicine, improved diagnostic tools, and personalized therapeutic approaches that address tumor heterogeneity. This review aims to provide a comprehensive overview of the current state of cancer diagnostics and treatments while highlighting emerging trends and challenges that lie ahead.

Colon cancer transcriptome

Over the last four decades, methodological innovations have continuously changed transcriptome profiling. It is now feasible to sequence and quantify the transcriptional outputs of individual cells or thousands of samples using RNA sequencing (RNA-seq). These transcriptomes serve as a connection between cellular behaviors and their underlying molecular mechanisms, such as mutations. This relationship, in the context of cancer, provides a chance to unravel tumor complexity and heterogeneity and uncover novel biomarkers or treatment options. Since colon cancer is one of the most frequent malignancies, its prognosis and diagnosis seem to be critical. The transcriptome technology is developing for an earlier and more accurate diagnosis of cancer which can provide better protectivity and prognostic utility to medical teams and patients. A transcriptome is a whole set of expressed coding and non-coding RNAs in an individual or cell population. The cancer transcriptome includes RNA-based changes. The combined genome and transcriptome of a patient may provide a comprehensive picture of their cancer, and this information is beginning to affect treatment decision-making in real-time. A full assessment of the transcriptome of colon (colorectal) cancer has been assessed in this review paper based on risk factors such as age, obesity, gender, alcohol use, race, and also different stages of cancer, as well as non-coding RNAs like circRNAs, miRNAs, lncRNAs, and siRNAs. Similarly, they have been examined independently in the transcriptome study of colon cancer.

Comprehensive landscape and future perspectives of long noncoding RNAs (lncRNAs) in colorectal cancer (CRC): Based on a bibliometric analysis

This review aimed to use bibliometric analysis to sort out, analyze and summarize the knowledge foundation and hot topics in the field of long noncoding RNAs (lncRNAs) in colorectal cancer (CRC), and point out future trends to inspire related research and innovation. We used CiteSpace to analyze publication outputs, countries, institutions, authors, journals, references, and keywords. Knowledge foundations, hotspots, and future trends were then depicted. The overall research showed the trend of biomedical-oriented multidisciplinary. Much evidence indicates that lncRNA plays the role of oncogene or tumor suppressor in the occurrence and development of CRC. Besides, many lncRNAs have multiple mechanisms. lncRNAs and metastasis of CRC, lncRNAs and drug resistance of CRC, and the clinical application of lncRNAs in CRC are current research hotspots. Through insight into the development trend of lncRNAs in CRC, this study will help researchers extract hidden valuable information for further research.

A Review on the Role of AFAP1-AS1 in the Pathoetiology of Cancer

AFAP1-AS1 is a long non-coding RNA which partakes in the pathoetiology of several cancers. The sense protein coding gene from this locus partakes in the regulation of cytophagy, cell motility, invasive characteristics of cells and metastatic ability. In addition to acting in concert with AFAP1, AFAP1-AS1 can sequester a number of cancer-related miRNAs, thus affecting activity of signaling pathways involved in cancer progression. Most of animal studies have confirmed that AFAP1-AS1 silencing can reduce tumor volume and invasive behavior of tumor cells in the xenograft models. Moreover, statistical analyses in the human subjects have shown strong correlation between expression levels of this lncRNA and clinical outcomes. In the present work, we review the impact of AFAP1-AS1 in the carcinogenesis.

Overexpression of lncRNA AFAP1-AS1 as a diagnostic biomarker in non-small cell lung cancer

Background

Long non-coding RNAs (lncRNAs) play important roles in lung tumorigenesis. Among different lncRNAs, overexpression of the lncRNA actin filament‐associated protein 1‐antisense RNA 1 (AFAP1-AS1) in lung tumors has been reported in different studies. In the current study, we aimed to investigate the potential value of lncRNA AFAP1-AS1 as a diagnostic biomarker in lung cancer. Ninety samples from patients with lung cancer were collected from Noor-E-Nejat hospital, Tabriz, Iran. The expression of AFAP1-AS1 was assessed using quantitative reverse transcriptase-PCR (qRT-PCR), followed by the ROC curve analysis to investigate the biomarker potency of AFAP1-AS1.

Results

Our results revealed an upregulation of AFAP1-AS1 in tumor samples as compared to the adjacent non-tumor tissues. We found a significant positive association between AFAP1-AS1 expression and tumor size, as well as tumor stage.

Conclusions

Our results showed overexpression of AFAP1-AS1 and its capacity as a diagnostic biomarker in lung cancer.

LncRNA AFAP1-AS1 Promotes the Progression of Colorectal Cancer through miR-195-5p and WISP1

Objective

Colorectal cancer (CRC) is the most common cancer. But, the molecular mechanisms of CRC progression are not fully understood. This study was conducted to explore how the long noncoding RNA actin filament-associated protein 1-antisense RNA1 (lncRNA AFAP1-AS1) participates in CRC progression through the regulation of microRNA-195-5p (miR-195-5p) and wingless-type inducible signaling pathway protein-1 (WISP1).

Methods

The expressions of AFAP1-AS1, miR-195-5p, and WISP1 were detected by RT-qPCR or western blot. A dual-luciferase assay confirmed the target relationship of AFAP1-AS1, miR-195-5p, and WISP1. Colony formation, wound-healing, and Transwell assays were used to detect the growth, migration, and invasion abilities of cells, respectively.

Results

AFAP1-AS1 and WISP1 expressions were notably increased, and miR-195-5p expression was markedly reduced in CRC. The dual-luciferase assay verified that AFAP1-AS1 could bind to miR-195-5p. AFAP1-AS1 knockdown could inhibit the malignant behavior of CRC cells. miR-195-5p could target and regulate WISP1 expression. Overexpression of WISP1 or miR-195-5p inhibition reversed the inhibition effect of AFAP1-AS1 knockdown on the biological activity of CRC cells.

Conclusions

AFAP1-AS1 knockdown may inhibit the proliferation, migration, and invasion of CRC cells through the miR-195-5p/WISP1 axis.

Long non-coding RNA AFAP1-AS1 accelerates lung cancer cells migration and invasion by interacting with SNIP1 to upregulate c-Myc

Actin filament associated protein 1 antisense RNA 1 (named AFAP1-AS1) is a long non-coding RNA and overexpressed in many cancers. This study aimed to identify the role and mechanism of AFAP1-AS1 in lung cancer. The AFAP1-AS1 expression was firstly assessed in 187 paraffin-embedded lung cancer and 36 normal lung epithelial tissues by in situ hybridization. The migration and invasion abilities of AFAP1-AS1 were investigated in lung cancer cells. To uncover the molecular mechanism about AFAP1-AS1 function in lung cancer, we screened proteins that interact with AFAP1-AS1 by RNA pull down and the mass spectrometry analyses. AFAP1-AS1 was highly expressed in lung cancer clinical tissues and its expression was positively correlated with lung cancer patients’ poor prognosis. In vivo experiments confirmed that AFAP1-AS1 could promote lung cancer metastasis. AFAP1-AS1 promoted lung cancer cells migration and invasion through interacting with Smad nuclear interacting protein 1 (named SNIP1), which inhibited ubiquitination and degradation of c-Myc protein. Upregulation of c-Myc molecule in turn promoted the expression of ZEB1, ZEB2, and SNAIL gene, which ultimately enhanced epithelial to mesenchymal transition (EMT) and lung cancer metastasis. Understanding the molecular mechanism by which AFAP1-AS1 promotes lung cancer’s migration and invasion may provide novel therapeutic targets for lung cancer patients’ early diagnosis and therapy.

AFAP1-AS1: a rising star among oncogenic long non-coding RNAs

Long non-coding RNAs (lncRNAs) have become a hotspot in biomedical research. This interest reflects their extensive involvement in the regulation of the expression of other genes, and their influence on the occurrence and development of a variety of human diseases. Actin filament associated protein 1-Antisense RNA 1(AFAP1-AS1) is a recently discovered oncogenic lncRNA. It is highly expressed in a variety of solid tumors, and regulates the expression of downstream genes and signaling pathways through adsorption and competing microRNAs, or by the direct binding to other proteins. Ultimately, AFAP1-AS1 promotes proliferation, chemotherapy resistance, and resistance to apoptosis, maintains stemness, and enhances invasion and migration of tumor cells. This paper summarizes the research concerning AFAP1-AS1 in malignant tumors, including the clinical application prospects of AFAP1-AS1 as a potential molecular marker and therapeutic target of malignant tumors. We also discuss the limitations in the knowledge of AFAP1-AS1 and directions of further research. AFAP1-AS1 is expected to provide an example for studies of other lncRNA molecules.

SP1-induced AFAP1-AS1 contributes to proliferation and invasion by regulating miR-497-5p/CELF1 pathway in nasopharyngeal carcinoma

Nasopharyngeal carcinoma is a type of otolaryngological malignancy with high incidence. Long non-coding RNAs (lncRNAs) are closely related to nasopharyngeal carcinoma. LncRNA AFAP1-AS1 (AFAP1-AS1) has been found to play important roles in nasopharyngeal carcinoma progression and poor prognosis. However, the mechanism underlying AFAP1-AS1 in regulating nasopharyngeal carcinoma is still unclear. In current study, AFAP1-AS1 was found to be up-regulated in nasopharyngeal carcinoma tissues and cells. AFAP1-AS1 overexpression and knockdown were conducted in nasopharyngeal carcinoma cells. The results proved that AFAP1-AS1 promoted the survival and migration of nasopharyngeal carcinoma cells. Additionally, specificity protein 1 (SP1) was enhanced in nasopharyngeal carcinoma tissues and cells, and induced AFAP1-AS1 expression. The interaction between AFAP1-AS1 and miR-497-5p was confirmed. AFAP1-AS1 was demonstrated to regulate CELF1, a target gene of miR-497-5p. Further functional analysis revealed that AFAP1-AS1 knockdown attenuated SP1-induced nasopharyngeal carcinoma progression. These results indicate that SP1-induced AFAP1-AS1 facilitates nasopharyngeal carcinoma progression by regulating miR-497-5p/CELF1 pathway, which provides a new target for nasopharyngeal carcinoma treatment.

Long non-coding RNA (lncRNA) and epithelial-mesenchymal transition (EMT) in colorectal cancer: a systematic review

BACKGROUND

Colorectal cancer (CRC) is a leading cause of cancer-related death. Epithelial-mesenchymal transition (EMT) is a major process in tumor metastasis development. This systematic review aims to describe the role of long non-coding RNA (lncRNA) in EMT in CRC.

METHODS

The electronic databases, PubMed, Cochrane, and EMBASE, were searched from January1990 to June 2019 to identify studies examining lncRNA and their role in mediating EMT in CRC. Studies examining clinical specimens and/or in vitro experiments were included.

RESULTS

In 61 identified studies, 54 lncRNAs were increased in CRC compared to normal colorectal epithelium. Increased lncRNA expression was frequently associated with worse survival. Many lncRNAs mediate their effect through competitive endogenous RNA or transcription factor regulation. The ZEB1, 2/E-cadherin, Wnt/β-catenin signaling, and chromatin remodeling pathways are discussed in particular.

CONCLUSIONS

lncRNAs are major regulators of EMT and predictor adverse outcome in CRC patients. Future research must focus on delineating lncRNA function prior to potential clinical use.

Long non-coding RNAs as potential markers for occurrence, progression, and prognosis of gastric cancer

In recent years, more and more attention has been paid to the relationship between long non-coding RNAs (lncRNAs) and tumor. Abnormal expression of lncRNAs plays an oncogenic or tumor-suppressing role in gastric cancer (GC) by participating in the biological behaviors of GC cells, such as proliferation, invasion, and migration. By summarizing the relevant literature, this paper discusses the research status, detection technology, and mechanism of action of lncRNAs in GC, as well as their potential as markers for occurrence, progression, prognosis, and drug resistance of GC. It is expected that lncRNAs can play an important role in early detection, early treatment, and effective improvement of chemotherapy resistance of GC to achieve personalized precise treatment of this malignancy.

lncRNA AFAP1-AS1 promotes triple negative breast cancer cell proliferation and invasion via targeting miR-145 to regulate MTH1 expression

The actin fiber-associated protein 1-antisense RNA1 (AFAP1-AS1) is upregulated in various cancers and associated with cancer proliferation and metastasis. Several cancer-related pathways have been linked to up-expression of this long non-coding (lnc)RNA, but the underlying mechanisms are yet unknown. In triple negative breast cancer (TNBC), AFAP1-AS1 expression is also significantly overexpressed compared to that in other subtypes of breast cancer from the TCGA dataset. In this study, we performed bioinformatic RNAhybrid analyses and identified that miR-145 is a potential target of AFAP1-AS1 and able to reduce MutT homolog-1 (MTH1) expression. Thus, this study investigated the oncogenic activity of AFAP1-AS1 in TNBC cells and the underlying mechanisms that are yet poorly understood. The results showed that miR-145 expression was low, whereas AFAP1-AS1 and MTH1 expression was high in TNBC cells and that miR-145 mimics reduced TNBC cell proliferation and invasion, whereas miR-145 knockdown exerted the opposite activity in TNBC cells. Moreover, knockdown of AFAP1-AS1 reduced tumor cell proliferation and invasion, but miR-145 co-transfection rescued tumor cell viability and colony formation ability. The dual luciferase reporter assay showed that AFAP1-AS1 could directly target miR-145, while miR-145 could directly target MTH1. After knockdown of ATF6, AFAP1-AS1 was reduced along with AFAP1-AS1 promoter activity. This study revealed that AFAP1-AS1 could promote TNBC cell proliferation and invasion via regulation of MTH1 expression through targeting of miR-145.

Bidirectional interaction of lncRNA AFAP1-AS1 and CRKL accelerates the proliferative and metastatic abilities of hepatocarcinoma cells

Actin filament-associated protein 1 antisense RNA 1 (AFAP1-AS1), a long non-coding RNA transcribed from the antisense strand of protein coding gene AFAP1, has attracted attention in cancer research. Despite, its biological function and regulatory mechanism in hepatocellular carcinoma still unknown. The present study revealed AFAP1-AS1 mediated hepatocarcinoma progression through targeting CRKL. The bidirectional interaction of AFAP1-AS1 and oncogenic protein CRKL, and the deregulation of AFAP1-AS1 effects on Ras, MEK and c-Jun activities were investigated in depth. AFAP1-AS1 was upregulated in surgical tumorous tissues from hepatocarcinoma patients compared with the paired paracancerous non-tumor liver tissues, and in hepatocarcinoma Huh7, HCCLM3 and HepG2 cell lines compared with LO2, a normal liver cell line. AFAP1-AS1 knockdown noticeably suppressed the proliferative, migratory and invasive properties, and the epithelial-mesenchymal transition (EMT) process of HepG2 and HCCLM3 through upregulating E-cadherin and downregulating N-cadherin and vimentin. CRKL knockdown reduced AFAP1-AS1 expression levels in HepG2 and HCCLM3 cells. AFAP1-AS1 suppression impaired CRKL expression in HepG2 and HCCLM3. AFAP1-AS1 level change was positively correlated with the expression level changes of Ras, MEK and c-Jun in mediating the invasiveness of hepatocarcinoma cells. Current work demonstrated AFAP1-AS1 to be an applicable progression indicator of hepatocarcinoma. AFAP1-AS1 probably promotes the proliferation, EMT progression and metastasis of hepatocarcinoma cells via CRKL mediated Ras/MEK/c-Jun and cadherin/vimentin signaling pathways. AFAP1-AS1-CRKL bidirectional feedback signaling is worthy of further study on the monitoring, diagnosis and treatment of cancers.

LINC00858 promotes colorectal cancer by sponging miR-4766-5p to regulate PAK2

OBJECTIVES

LncRNAs (long noncoding RNAs) have been reported to critically regulate colorectal cancer (CRC). We prospectively investigated effects and mechanisms of lncRNA LINC00858 on regulation of CRC progression.

METHODS

Expression of LINC00858 and its target were analyzed by quantitative real-time polymerase chain reaction and in situ hybridization. MTT and bromodeoxyuridine/5-bromo-2'-deoxyuridine (BrdU) staining to assess cell proliferation ability. Flow cytometry, wound healing, and transwell assays were conducted to evaluate cell apoptosis, migration, and invasion, respectively. Interaction between LINC00858 and its target was confirmed by luciferase activity assay and RNA immunoprecipitation. Subcutaneous xenotransplanted tumor model was established and employed to detect tumorigenic functions of LINC00858, and further evaluated by qRT-PCR, western blot, immunohistochemistry, and hematoxylin and eosin staining.

RESULTS

With a predicted poor prognosis, LINC00858 was upregulated in CRC patients. LINC00858 knockdown suppressed cell proliferation, invasion, and migration abilities, meanwhile induced cell apoptosis. Moreover, LINC00858 could target and inhibit the miR-4766-5p expression, thus promoting CRC progression. miR-4766-5p further suppressed serine/threonine kinase PAK2. Interestingly, interference of LINC00858 suppressed tumorigenic ability of CRC in vivo by downregulating PAK2.

CONCLUSIONS

LINC00858 promoted CRC progression by sponging miR-4766 to upregulate PAK2, shedding lights on LINC00858 as a potential therapeutic target candidate in CRC treatment from bench to clinic.

The long coding RNA AFAP1-AS1 promotes tumor cell growth and invasion in pancreatic cancer through upregulating the IGF1R oncogene via sequestration of miR-133a

Long non-coding RNAs (lncRNAs) have been shown to play a significant role in the progression of many cancers, including pancreatic cancer (PC). However, the biological function and regulatory mechanisms of lncRNAs in PC remains largely unclear. The aim of this study was to identify and evaluate the potential functions of lncRNAs in PC and reveal the underlying mechanisms of their effects. Screening of published microarray data (GEO accession Nos. GSE16515 and GSE32688), revealed lncRNA AFAP1-AS1 to be one of the most upregulated lncRNAs in PC tissues. High expression of AFAP1-AS1 was correlated with advanced stages, tumor size and lymph node metastasis, as well as with poorer overall survival in patients with PC. Functionally, knockdown of AFAP1-AS1 by transfection with siRNA inhibited the proliferative and invasive capacities of PaCa-2 and SW1990 PC cells, promoted apoptosis of PC cells in vitro, and impaired in-vivo tumorigenicity. In particular, it was hypothesized that AFAP1-AS1 may act as a competitive endogenous RNA (ceRNA), effectively becoming a sink for miR-133a whose expression was found to be downregulated in PC tissues and cell lines, and which was negatively correlated with the expression of AFAP1-AS1. We also found that the IGF1R oncogene which is an important regulator of MEK/ERK signaling pathway, was positively regulated by AFAP1-AS1 through ameliorating miR-133a-mediated IGF1R repression in PC tissues. Moreover, we demonstrated that knockdown of IGF1R by transfection with si-IGF1R suppressed cell proliferation, invasion and migration of PaCa-2 and SW1990 PC cells, suggesting that IGF1R may function as an oncogene in PC cells. Further investigations revealed that miR-133a reversed the biological effects of AFAP1-AS1 on PC cells. Collectively, the findings provide new evidence that AFAP1-AS1 could regulate the progression of pancreatic cancer by acting as a ceRNA, and suggest it has potential for use as both a biomarker for the early detection PC and for the development of individualized therapies for PC.

Long non-coding RNA AFAP1-AS1 promotes proliferation and invasion in prostate cancer via targeting miR-512-3p

BACKGROUND (OBJECTIVE)

In the development of tumor therapy, the role of long non-coding RNA actin filagenin 1 antisense RNA 1 (1ncRNA AFAP1-AS1) is quite significant, but the actual role of AFAP1-AS1 in the treatment of prostate cancer has not been determined. In view of this, the author took AFAP1-AS1 as the research object to design an experimental study, and conducted an in-depth exploration of the pathogenesis of prostate cancer.

METHODS

RT-qPCR was used to detect the expression of AFAP1-AS1 and miR-512-3p in prostate cancer tissues and cell lines. Perforation, flow cytometry and CCK-8 were used to detect the effects of cell proliferation, migration and invasion of mir-512-3p and a AFAP1-AS1. And the luciferase reporter gene was used to detect the downstream target gene of AFAP1-AS1, and the expression of CDK4, CDK6 and CCND1 protein was detected by Western blot.

RESULTS

AFAP1-AS1 is highly expressed in prostate cancer tissues and cell lines. The expression level of AFAP1-AS1 is correlated with histological grade and distant metastasis. The overall level of patients with high expression of AFAP1-AS1 is low, and their survival rate is relatively low. Silencing AFAP1-AS1 can significantly increase the proliferation and migration of prostate cancer cells. AFAP1-AS1 silencing induces cell cycle arrest at G0/G1 phase. The downstream target of AFAP1-AS1 was mir-512-3p. The role of AFAP1-AS1 in the progression of prostate cancer cells was mediated by mir-512-3p.

CONCLUSION

AFAP1-AS1 regulates miR-512-3p, so as to realize the regulation effect on the proliferation, invasion and migration of prostate cancer cells, and thereby promote the occurrence and development of prostate cancer, so as to provide the corresponding program for the treatment of prostate cancer. Abberivation: ADPC, androgen-dependent prostate cancer; CRPC, castrated prostate cancer; RNA1 AFAP1-Asl, Actin fiber-associated protein 1-anti-RNA1; miRNAs, MicroRNAs.

Changing expression profiles of lncRNAs, circRNAs and mRNAs in esophageal squamous carcinoma

Abundant evidence indicates that long noncoding RNAs (lncRNAs) and circular RNAs (circRNAs) serve important roles in tumorigenesis and tumour progression. However, their diagnostic and treatment value for esophageal squamous carcinoma (ESCC) remains unknown. A microarray (SBC human ceRNA array V1.0) was performed to assess the expression profiles and biological functions of lncRNAs, circRNAs and mRNAs in ESCC and para-cancerous tissues from three patients. Microarray data were validated by reverse transcription-quantitative polymerase chain reaction for a group of genes. A number of lncRNA-microRNAs (miRNA) and circRNA-miRNA-mRNA networks were constructed. Bioinformatics tools, including gene ontology and Kyoto Encyclopedia of Genes and Genomes biological pathway analyses, were used to predict the functions of differentially expressed lncRNAs, circRNAs and potentially co-expressed target genes. The results revealed that compared with the expression levels of para-cancerous tissues, 1,384 lncRNAs, 2,046 circRNAs and 936 mRNAs were frequently altered in ESCC tissues. Co-expression networks of lncRNAs-miRNAs-circRNAs-mRNAs were constructed based on the correlation analyses among the differentially expressed RNAs. Furthermore, using bioinformatics methods, correlation expression networks were constructed that included cis- and trans-regulatory elements. Therefore, these results suggest that lncRNAs and circRNAs may be involved in the pathogenesis and development of ESCC. These findings provide a novel and systematic perspective on the potential function of noncoding RNAs in ESCC.

Diagnostic and prognostic potential of tissue and circulating long non-coding RNAs in colorectal tumors

Long non-coding RNAs (lncRNAs) are members of the non-protein coding RNA family longer than 200 nucleotides. They participate in the regulation of gene and protein expression influencing apoptosis, cell proliferation and immune responses, thereby playing a critical role in the development and progression of various cancers, including colorectal cancer (CRC). As CRC is one of the most frequently diagnosed malignancies worldwide with high mortality, its screening and early detection are crucial, so the identification of disease-specific biomarkers is necessary. LncRNAs are promising candidates as they are involved in carcinogenesis, and certain lncRNAs (e.g., CCAT1, CRNDE, CRCAL1-4) show altered expression in adenomas, making them potential early diagnostic markers. In addition to being useful as tissue-specific markers, analysis of circulating lncRNAs (e.g., CCAT1, CCAT2, BLACAT1, CRNDE, NEAT1, UCA1) in peripheral blood offers the possibility to establish minimally invasive, liquid biopsy-based diagnostic tests. This review article aims to describe the origin, structure, and functions of lncRNAs and to discuss their contribution to CRC development. Moreover, our purpose is to summarise lncRNAs showing altered expression levels during tumor formation in both colon tissue and plasma/serum samples and to demonstrate their clinical implications as diagnostic or prognostic biomarkers for CRC.

LncRNA AFAP1-AS1 promotes tumorigenesis and epithelial-mesenchymal transition of osteosarcoma through RhoC/ROCK1/p38MAPK/Twist1 signaling pathway

Background

An increasing number of studies have demonstrated that long non-coding RNAs (lncRNAs) play pivotal roles in cancer onset and development. LncRNA AFAP1-AS1 has been validated to be abnormally upregulated and play oncogenic roles in various malignant tumors. The biological role and mechanism of AFAP1-AS1 in OS (osteosarcoma) remains unclear.

Methods

Quantitative reverse transcription PCR (qRT-PCR) is applied to examine AFAP1-AS1 expression in OS tissues and OS cell lines. The function of AFAP1-AS1 in OS cells is investigated via in-vitro and in-vivo assays. Western bolt and rescue experiments are applied to detect the expression changes of key molecules including epithelial-mesenchymal transition markers and identify the underlying molecular mechanism. RNA immunoprecipitation is performed to reveal the interaction between AFAP1-AS1 and RhoC.

Results

AFAP1-AS1 expression is upregulated in human OS tissues and cell lines. AFAP1-AS1 knockdown induces OS cell apoptosis and cell cycle G0/G1 arrest, suppresses OS cells growth, migration, invasion, vasculogenic mimicry formation and epithelial-mesenchymal transition (EMT), and affects actin filament integrity. AFAP1-AS1 knockdown suppresses OS tumor formation and growth in nude mice. AFAP1-AS1 knockdown elicits a signaling inhibition including decreased levels of RhoC, ROCK1, p38MAPK and Twist1. Moreover, AFAP1-AS1 interacts with RhoC. Overexpression of RhoC can partly reverse AFAP1-AS1 downregulation-induced cell EMT inhibition.

Conclusions

AFAP1-AS1 is overexpressed in osteosarcoma and plays an oncogenic role in osteosarcoma through RhoC/ROCK1/p38MAPK/Twist1 signaling pathway, in which RhoC acts as the interaction target of AFAP1-AS1. Our findings indicated a novel molecular mechanism underlying the tumorigenesis and progression of osteosarcoma. AFAP1-AS1 could serve as a promising therapeutic target in OS treatment.

Electronic supplementary material

The online version of this article (10.1186/s13046-019-1363-0) contains supplementary material, which is available to authorized users.

Downregulation of lncRNA AFAP1-AS1 by oridonin inhibits the epithelial-to-mesenchymal transition and proliferation of pancreatic cancer cells

Recent studies have demonstrated that the expression of the long non-coding RNA (lncRNA) AFAP1-AS1 in pancreatic cancer is negatively correlated with survival and prognosis. However, the effects of oridonin and lncRNA AFAP1-AS1 on the epithelial-to-mesenchymal transition (EMT) and migration of pancreatic cancer cells have not been fully elucidated. Surgery is the only potentially curative method for pancreatic cancer, but postoperative recurrence and metastasis are common. The aim of the present study was to assess the effect of oridonin and lncRNA AFAP1-AS1 silencing on pancreatic cancer cells. The pancreatic cancer cell lines BxPC-3 and PANC-1 cells were transfected with siAFAP1-AS1 and its negative control (siNC). After that, oridonin was used to treat the siAFAP1-AS1-transfected cells. The expression of lncRNA AFAP1-AS1 was downregulated in the pancreatic cancer cell lines BxPC-3 and PANC-1. The apoptosis and cell cycle progression of pancreatic cancer cells were evaluated by flow cytometry and Hoechst 33258 staining. Metastasis and invasion of BxPC-3 and PANC-1 cells were detected by transwell migration assay, real-time cell analysis, and western blot analysis. Cells were transfected with the lentiviral siAFAP1-AS1 and siNC, and tumorigenesis was evaluated in BALB/C nude mice. Immunohistochemical examination was used to verify the effects of oridonin and siAFAP1-AS1 on pancreatic cancer. The results demonstrated that the combination of oridonin and siAFAP1-AS1 inhibited pancreatic cancer cell proliferation, induced apoptosis, arrested cell cycle progression, prevented the migration, regulated EMT-related protein expression in BxPC-3 and PANC-1 cells, and inhibited pancreatic cancer cell tumorigenicity and EMT in nude mice.

Overexpression of lncRNA AFAP1-AS1 promotes cell proliferation and invasion in gastric cancer

Long non-coding RNA (lncRNA) actin filament-associated protein 1 antisense RNA 1 (AFAP1-AS1) has been revealed to be associated with certain types of cancer. However, whether the lncRNA AFAP1-AS1 is involved in the development and progression of gastric cancer (GC) remains unknown. The present study investigated the clinical significance and biological functions of AFAP1-AS1 in GC. The expression levels of lncRNA AFAP1-AS1 in 52 patients with GC, and in 1 normal gastric mucosal cell line and 3 GC cell lines, were evaluated by reverse transcription quantitative polymerase chain reaction analysis. Small interfering RNAs were used to suppress AFAP1-AS1 expression in GC cell lines. The results indicated that AFAP1-AS1 expression levels were significantly increased in GC tissues and cell lines compared with the corresponding noncancerous tissues and normal gastric cells. In addition, the patients with GC with increased AFAP1-AS1 expression exhibited an advanced clinical stage and an association with the occurrence of lymph node metastasis compared with those with decreased AFAP1-AS1 expression. In vitro assays demonstrated that knockdown of AFAP1-AS1 decreased levels of cell proliferation and migration. In addition, the results of flow cytometry demonstrated that knockdown of AFAP1-AS1 caused cell cycle arrest. In conclusion, AFAP1-AS1 is a novel molecule involved in GC progression, which may be a potential prognostic biomarker and target for therapeutic intervention.

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.

LncRNAs with miRNAs in regulation of gastric, liver, and colorectal cancers: updates in recent years

Long noncoding RNA (lncRNA) is a kind of RNAi molecule composed of hundreds to thousands of nucleotides. There are several major types of functional lncRNAs which participate in some important cellular pathways. LncRNA-RNA interaction controls mRNA translation and degradation or serves as a microRNA (miRNA) sponge for silencing. LncRNA-protein interaction regulates protein activity in transcriptional activation and silencing. LncRNA guide, decoy, and scaffold regulate transcription regulators of enhancer or repressor region of the coding genes for alteration of expression. LncRNA plays a role in cellular responses including the following activities: regulation of chromatin structural modification and gene expression for epigenetic and cell function control, promotion of hematopoiesis and maturation of immunity, cell programming in stem cell and somatic cell development, modulation of pathogen infection, switching glycolysis and lipid metabolism, and initiation of autoimmune diseases. LncRNA, together with miRNA, are considered the critical elements in cancer development. It has been demonstrated that tumorigenesis could be driven by homeostatic imbalance of lncRNA/miRNA/cancer regulatory factors resulting in biochemical and physiological alterations inside the cells. Cancer-driven lncRNAs with other cellular RNAs, epigenetic modulators, or protein effectors may change gene expression level and affect the viability, immortality, and motility of the cells that facilitate cancer cell cycle rearrangement, angiogenesis, proliferation, and metastasis. Molecular medicine will be the future trend for development. LncRNA/miRNA could be one of the potential candidates in this category. Continuous studies in lncRNA functional discrepancy between cancer cells and normal cells and regional and rational genetic differences of lncRNA profiles are critical for clinical research which is beneficial for clinical practice.

Long non-coding RNA AFAP1-AS1 plays an oncogenic role in promoting cell migration in non-small cell lung cancer

Long non-coding RNA (lncRNA) plays an important role in tumor progression and metastasis. Emerging evidence indicates that lncRNA actin filament-associated protein 1-antisense RNA 1 (AFAP1-AS1) is dysregulated in certain tumors. However, the function of AFAP1-AS1 in non-small cell lung cancer (NSCLC) remains elusive. In this study, we conducted global lncRNA profiling and identified that AFAP1-AS1 is significantly upregulated in NSCLC, suggesting that AFAP1-AS1 may be important for lung cancer development. For the first time, the transcription initiation and termination sites of AFAP1-AS1 were identified by rapid amplification of cDNA ends technology, and the sequencing data indicated that AFAP1-AS1 in lung cancer cells is a novel transcript variant. Through gain- and loss-of-function studies, AFAP1-AS1 was demonstrated to promote cell migration and invasion. Mechanistically, AFAP1-AS1 functions through positively regulating the expression of AFAP1 protein. On the other hand, the expression of lncRNA AFAP1-AS1 negatively correlates with CpG methylation status of its gene promoter, identified in both lung cancer cells and patient tissues, and treatment with DNA methyltransferase inhibitor decitabine significantly activates AFAP1-AS1 expression, strongly supporting that AFAP1-AS1 expression is tightly regulated by DNA methylation. Taken together, this study demonstrates that AFAP1-AS1 acts as an oncogene in NSCLC to promote cell migration partly by upregulating AFAP1 expression, while its own expression is controlled by DNA methylation, and highlights its diagnostic and therapeutic values for NSCLC patients.

AFAP1-AS1 Promotes Epithelial-Mesenchymal Transition and Tumorigenesis Through Wnt/β-Catenin Signaling Pathway in Triple-Negative Breast Cancer

Long non-coding RNA (LncRNA) actin filament-associated protein1-antisense RNA 1 (AFAP1-AS1) is overexpressed in various types of cancers and plays an important role in tumor progression and prognosis. This study investigates the role of AFAP1-AS1 in tumor progression in triple-negative breast cancer (TNBC). We found that AFAP1-AS1 was overexpressed in TNBC tissues and cells. Overexpression of LncRNA AFAP1-AS1 was associated with poor prognosis in TNBC patients. Moreover, we demonstrated that upregulation of AFAP1-AS1 promoted cell proliferation and invasion, and inhibited cell apoptosis in vitro, while overexpression of AFAP1-AS1 promoted tumor growth in vivo. Our results also revealed that upregulation of AFAP1-AS1 activated Wnt/β-catenin pathway to promote tumorigenesis and cell invasion by increasing the expression of C-myc and epithelial-mesenchymal transition-related molecules in TNBC. Collectively, AFAP1-AS1 can be an independent prognostic marker and an effective therapeutic target of triple- negative breast cancer.

Expression analysis of AFAP1-AS1 and AFAP1 in breast cancer

Long non-coding RNAs (lncRNA) constitute a significant percentage of RNAs with no translation to proteins. Their participation in fundamental aspects of cell physiology as well as their dysregulation in a number of pathologic conditions such as cancer have been documented. Among lncRNAs is actin filament associated protein 1 antisense RNA1 (AFAP1-AS1) whose elevated expression levels have been demonstrated in different cancers. In the in the present study we evaluated expression levels of AFAP1-AS1 and its antisense protein coding gene AFAP1 in breast cancer samples compare with adjacent non-cancerous tissues (ANCTs) as well as breast cancer cell lines with special focus on the assessment of the association between their transcript levels and patients' clinicopathological data. AFAP1-AS1 has shown significant up-regulation in both MDA-MB-231 and MCF-7 compared with control sample. AFAP1-AS1 has been shown to be expressed in all of tumor tissues but 76% (39 out of 51) ANCTs. AFAP1 expression was not significantly different between tumor samples and ANCTs. AFAP1-AS1 has been demonstrated to be significantly up-regulated in tumor tissues compared with ANCTs (fold change = 4.65, P= 0.028). No significant correlation has been detected between the levels of these two transcripts in tumor tissues (R=2 0.081) or ANCTs (R=2 0.115). No significant associations have been found between expression levels of these genes and patients' characteristics. However, both genes were significantly down-regulated in Ki-67 negative tumor samples. The observed up-regulation of AFAP1-AS1 in tumor samples compared with ANCTs implies its involvement in breast cancer pathogenesis and potentiates it as a biomarker or therapeutic target.

The role of long non-coding RNA AFAP1-AS1 in human malignant tumors

OBJECTIVES

Long non-coding RNAs (lncRNAs) are a type Table of endogenous RNA longer than 200 nucleotides in length, and this kind of RNAs lack or possess limited ability of coding proteins. A large number of studies have demonstrated that lncRNAs could take part in massive biological processes, such as transcriptional activation and interference, cellular differentiation, proliferation, migration, invasion and apoptosis. The abnormal expression of lncRNAs has been clarified to play extremely important roles in various diseases, especially in human cancers. LncRNA actin filament-associated protein 1 antisense RNA 1 (AFAP1-AS1) is a newly recognized cancer-related lncRNA deriving from the antisense strand of DNA at the AFAP1 coding gene locus. A slew of new studies suggest that AFAP1-AS1 is involved in many kinds of malignant tumors. Moreover, in recent years, the dysregulated expression of AFAP1-AS1 has been confirmed to be associated with oncogenesis and tumor progression. Evidence has increasingly shown that AFAP1-AS1 could probably serve as a novel potential molecular biomarker in tumor diagnosis and therapeutic target in tumor treatment. In this review, we sum up present stage new hottest research issues in respect of the biological functions and molecular mechanisms of AFAP1-AS1 in occurrence and progression of human tumors.

MATERIALS AND METHODS

In this review, we summarize the recent researches about the expression and molecular biological mechanisms of lncRNA AFAP1-AS1 in tumor development. Existing relevant studies are acquired and analyzed by searching Pubmed, BioMedNet, GEO database and Academic Search Elit systematically.

RESULTS

Long non-coding RNA AFAP1-AS1 is an important tumor-associated lncRNA and its aberrant expression has been found in many malignancies so far, including pancreatic ductal adenocarcinoma, cholangiocarcinoma, gallbladder cancer, hepatocellular carcinoma, gastric cancer, colorectal cancer, esophageal cancer, nasopharyngeal carcinoma, lung cancer, ovarian cancer, breast cancer, retinoblastoma, laryngeal cancer, tongue squamous cell carcinoma and thyroid cancer. In addition, the dysregulated expression of AFAP1-AS1 is related to carcinogensis, overall survival (OS), disease-free survival (DFS), progression-free survival (PFS) and tumor progression containing lymph node metastasis, distant metastasis, histological grade, tumor size and tumor stage.

CONCLUSIONS

A series of studies provide detailed information to understand lncRNA AFAP1-AS1 role in various human cancers. LncRNA AFAP1-AS1 is an oncogene in tumors that have been studied so far, and it may act as a useful tumor biomarker and therapeutic target.

RAC1-GTP promotes epithelial-mesenchymal transition and invasion of colorectal cancer by activation of STAT3

Epithelial-mesenchymal transition (EMT) plays a critical role in initiating tumor invasion and metastasis of colorectal cancer (CRC), although the underlying mechanisms remain to be clarified. Herein, we demonstrate that the active form of Rac family small GTPase 1 (RAC1-GTP) is overexpressed in CRCs and promotes the EMT-mediated invasion of CRC cells through activation of the signal transducers and activators of transcription 3 (STAT3) pathway. Increased expression of RAC1-GTP in CRC tissues was positively correlated with the TNM stages of CRCs and indicated poor prognosis of CRC patients. Targeting RAC1-GTP activity by its specific inhibitor NSC23766 markedly suppressed the migration and invasion of CRC cells. Mechanistically, RAC1-GTP directly interacted with STAT3 to promote STAT3 phosphorylation, thus promoted EMT of CRC cells. Enforced expression of constitutively activated STAT3 (STAT3-C) abrogated the suppressive effect of RAC1-GTP disruption on the migration and invasion of CRC cells. Importantly, NSC23766 disrupted EMT in CRC cells and significantly diminished growth of CRC xenografts. Taken together, our data indicate that RAC1-GTP is an important player in EMT-mediated tumor invasion and a potential therapeutic target for CRCs.

Up-regulated lncRNA AFAP1-AS1 indicates a poor prognosis and promotes carcinogenesis of breast cancer

BACKGROUND

Long noncoding RNAs (lncRNAs) have been reported to play crucial roles in breast cancer. This study aimed to determine the clinical significance and biological functions of lncRNA AFAP1-AS1 in breast cancer.

METHODS

The expression of AFAP1-AS1 in breast cancer tissue and adjacent normal tissue from 160 patients and breast cancer cell lines were determined by qRT-PCR. The clinical characteristics of patients were collected to analyse the correlation between AFAP1-AS1 expression and malignancy status. Kaplan-Meier and Cox proportional hazards model were used to analyze whether AFAP1-AS1 expression impacted prognosis. To assess the effect of AFAP1-AS1 on MCF-7 cells proliferation, cell viability, EdU incorporation and colony formation assays were conducted after AFAP1-AS1 knockdown by siRNA. The apoptosis was detected by Caspase-3 activity, cell cycle analysis, Bcl-2 and Bax protein expression. Wound scratch assay and EMT-related protein expression (E-cadherin, N-cadherin and Vimentin) were conducted to evaluate the metastasis ability. To further determine the effect of AFAP1-AS1 on AFAP1, the mRNA and protein expression of AFAP1 and subsequent actin filament integrity were measured after AFAP1-AS1 knockdown.

RESULTS

The expression of AFAP1-AS1 was up-regulated in human breast cancer tissue and associated with malignancy status, high expression of AFAP1-AS1 had a poor prognosis in breast cancer patients. AFAP1-AS1 expression was up-regulated in 4 breast cancer cell lines (MCF-7, SK-RB-3, MDA-MB-231and MDA-MB-468) compared with normal breast cell line HBL-100. MCF-7, the most up-regulation cancer cell, was used for following studies. AFAP1-AS1 knockdown can inhibit the proliferation, metastasis and promote apoptosis of MCF-7. However, the AFAP1 expression and actin filament integrity was not affected after AFAP1-AS1 knockdown.

CONCLUSION

Up-regulated lncRNA AFAP1-AS1 indicates a poor prognosis in breast cancer patients and regulated the breast cancer cells proliferation, apoptosis and metastasis.

Long noncoding RNA AFAP1‑AS1 enhances cell proliferation and invasion in osteosarcoma through regulating miR‑4695‑5p/TCF4‑β‑catenin signaling

Long noncoding RNA AFAP1‑AS1 has been shown to promote tumor progression in several human cancer types, such as thyroid cancer, tongue squamous cell carcinoma and lung cancer. However, the role of AFAP1‑AS1 in osteosarcoma (OS) has not been investigated. In the present study, the expression of AFAP1‑AS1 was significantly upregulated in OS tissues and cell lines. Moreover, AFAP1‑AS1 expression was negatively correlated with OS patient prognosis. Besides, AFAP1‑AS1 knockdown significantly inhibited the proliferation and invasion of OS cells in vitro. Furthermore, in vivo xenograft experiments indicated that AFAP1‑AS1 depletion delayed tumor growth. Regarding the underlying mechanism, AFAP1‑AS1 served as a sponge to repress the level of microRNA (miR)‑4695‑5p, which targeted transcription factor (TCF)4, a pivot effector of Wnt/β‑catenin signaling pathway. It was demonstrated that overexpression of AFAP1‑AS1 inhibited the expression of miR‑4695‑5p, while miR‑4695‑5p overexpression decreased TCF4 expression and reduced activation of Wnt/β‑catenin pathway. Through rescue assays, it was demonstrated that restoration of TCF4 expression reversed the effects of AFAP1‑AS1 knockdown or miR‑4695‑5p overexpression on OS cells. Taken together, these findings demonstrated that the AFAP1‑AS1/miR‑4695‑5p/TCF4‑β‑catenin axis played an important role in OS progression.

LncRNA AFAP1-AS1 is a prognostic biomarker and serves as oncogenic role in retinoblastoma

The actin filament-associated protein 1 antisense RNA 1 (AFAP1-AS1) has been found to serve as an oncogenic long noncoding RNA (lncRNA) in most types of human cancer. The role of AFAP1-AS1 in retinoblastoma remains unknown. The purpose of the present study is to explore the clinical significance and biological function of AFAP1-AS1 in retinoblastoma. Levels of AFAP1-AS1 expression were measured in retinoblastoma tissues and cell lines. Loss-of-function study was performed to observe the effects of AFAP1-AS1 on retinoblastoma cell proliferation, cell cycle, migration, and invasion. In our results, AFAP1-AS1 expression was elevated in retinoblastoma tissues and cell lines, and associated with tumor size, choroidal invasion, and optic nerve invasion. Moreover, high expression of AFAP1-AS1 was an independent unfavorable prognostic factor in retinoblastoma patients. The experiment in vitro suggested down-regulation of AFAP1-AS1 inhibited retinoblastoma cell proliferation, migration and invasion, and blocked cell cycle. In conclusion, AFAP1-AS1 functions as an oncogenic lncRNA in retinoblastoma.

Long noncoding RNA AFAP1-AS1 facilitates tumor growth through enhancer of zeste homolog 2 in colorectal cancer

Increasing evidences have shown that long noncoding RNAs (lncRNAs) play critical regulatory roles in cancer biology. However, the contributions of lncRNAs to colorectal cancer remain largely unknown. Here, we identify a lncRNA AFAP1-AS1 that facilitates colorectal cancer, where it is upregulated. AFAP1-AS1 expression was associated with colorectal cancer patient survival. AFAP1-AS1 knockdown inhibited cell proliferation, cell cycle, and tumorigenesis in an subcutaneous mouse xenograft model system. Further data demonstrated that AFAP1-AS1 was associated with enhancer of zeste homolog 2 (EZH2) and that this association was required for the repression of EZH2 target genes. Our findings indicate that AFAP1-AS1 is an oncogenic lncRNA that promotes tumor progression and may be a novel prognostic factor in colorectal cancer. Targeting AFAP1-AS1 might be a potential therapeutic strategy for colorectal cancer treatment.

Long non-coding RNA AFAP1-antisense RNA 1 promotes the proliferation, migration and invasion of gastric cancer cells and is associated with poor patient survival

Gastric cancer (GC) is the second-leading cause of cancer-associated mortality worldwide. AFAP1-antisense RNA 1 (AFAP1-AS1), a long non-coding RNA (lncRNA), is believed to promote the aggressive progression of cancer; however, its role in GC remains largely unknown. In the present study, the expression of AFAP1-AS1 in GC tissues and cell lines was measured using reverse transcription-quantitative polymerase chain reaction (RT-qPCR). Knockdown of AFAP1-AS1 was performed using a lentiviral vector containing a short hairpin RNA. The proliferation of GC cells was measured using Cell Counting kit-8. The migration and invasion of GC cells were analyzed using a QCM Laminin Migration Assay kit and a Cell Invasion Assay kit. The levels of epithelial-mesenchymal transition (EMT)-associated proteins were detected by western blot analysis. The cut-off value of the expression of AFAP1-AS1 was evaluated using receiver operating characteristic (ROC) curves and patient survival rate was analyzed using Kaplan-Meier. The expression of AFAP1-AS1 was significantly increased in the primary tumor tissues of GC patients with lymph node metastasis or tumor node metastasis stage (stage III or IV; P<0.01). ROC curve analysis revealed that the expression of AFAP-AS1, at a cut-off value of 0.5040, could distinguish GC tissues from the matched normal tissues, with an AUC of 0.8802, sensitivity of 81.25% and specificity of 83.75%. The overexpression of AFAP1-AS1 was positively associated with the poor survival rates of GC patients. Furthermore, the downregulation of AFAP1-AS1 significantly inhibited the proliferation, migration and invasion of GC cells in vitro (P<0.01). The decrease in AFAP1-AS1 expression significantly suppressed the expression level of N-cadherin protein in GC cells and increased that of E-cadherin. The present study demonstrated that the expression signature of AFAP1-AS1 may serve as a biomarker for the diagnosis and prognosis of GC, and its downregulation may repress the aggressive progression of GC, partially through inhibiting the EMT progress.

Knockdown of long non-coding RNA AFAP1-AS1 inhibits growth and promotes apoptosis in pituitary adenomas

Recent studies have reported that the long non-coding RNA (lncRNA) AFAP antisense RNA 1 (AFAP1-AS1) is involved in various biological processes and plays a key role in regulating cancer growth and metastasis in humans. However, its effects on tumorigenesis in pituitary adenomas remain unclear. The present study investigated the expression and biological role of AFAP1-AS1 in pituitary adenomas. We observed that the expression of AFAP1-AS1 was considerably higher in the pituitary adenoma tissues as compared to its expression in the adjacent tissues. Additionally, knockdown of AFAP1-AS1 inhibited the proliferation, arrested the cell cycle in the G1-to-S transition phase, and promoted apoptosis in GH3 and MMQ cells. Finally, knockdown of AFAP1-AS1 also promoted the expression of PTEN and inhibited the expression of PI3K and p-AKT. Our results provided novel insights into the function and mechanism of action of AFAP1-AS1 in the pathogenesis of pituitary adenomas.

AFAP1-AS1: A novel oncogenic long non-coding RNA in human cancers

Long non-coding RNAs (lncRNAs), a group of non-protein-coding RNAs with more than 200 nucleotides in length, are involved in multiple biological processes, such as the proliferation, apoptosis, migration and invasion. Moreover, numerous studies have shown that lncRNAs play important roles as oncogenes or tumour suppressor genes in human cancers. In this paper, we concentrate on actin filament-associated protein 1-antisense RNA 1 (AFAP1-AS1), a well-known long non-coding RNA that is overexpressed in various tumour tissues and cell lines, including oesophageal cancer, pancreatic ductal adenocarcinoma, nasopharyngeal carcinoma, lung cancer, hepatocellular carcinoma, ovarian cancer, colorectal cancer, biliary tract cancer and gastric cancer. Moreover, high expression of AFAP1-AS1 was associated with the clinicopathological features and cancer progression. In this review, we sum up the current studies on the characteristics of AFAP1-AS1 in the biological function and mechanism of human cancers.

Upregulation of the long non-coding RNA AFAP1-AS1 affects the proliferation, invasion and survival of tongue squamous cell carcinoma via the Wnt/β-catenin signaling pathway

Background

Long non-coding RNA (lncRNA) actin filament associated protein 1 antisense RNA1 (AFAP1-AS1) is oriented in an antisense direction to the protein-coding gene AFAP1 in the opposite strand. Previous studies showed that lncRNA AFAP1-AS1 was upregulated and acted as an oncogene in a variety of tumors. However, the expression and biological functions of lncRNA AFAP1-AS1 in tongue squamous cell carcinoma (TSCC) are still unknown.

Methods

The expression level of AFAP1-AS1 was measured in 103 pairs of human TSCC tissues and corresponding adjacent normal tongue mucous tissues. The correlation between AFAP1-AS1 and the clinicopathological features was evaluated using the chi-square test. The effects of AFAP1-AS1 on TSCC cells were determined via a CCK-8 assay, clone formation assay, flow cytometry, wound healing assay and transwell assay. Furthermore, the effect of AFAP1-AS1 knockdown on the activation of the Wnt/β-catenin signaling pathway was investigated. Finally, CAL-27 cells with AFAP1-AS1 knockdown were subcutaneously injected into nude mice to evaluate the effect of AFAP1-AS1 on tumor growth in vivo.

Results

In this study, we found that lncRNA AFAP1-AS1 was increased in TSCC tissues and that patients with high AFAP1-AS1 expression had a shorter overall survival. Short hairpin RNA (shRNA)-mediated AFAP1-AS1 knockdown significantly decreased the proliferation of TSCC cells. Furthermore, AFAP1-AS1 silencing partly inhibited cell migration and invasion. Inhibition of AFAP1-AS1 decreased the activity of the Wnt/β-catenin pathway and suppressed the expression of EMT-related genes (SLUG, SNAIL1, VIM, CADN, ZEB1, ZEB2, SMAD2 and TWIST1) in TSCC cells. In addition, CAL-27 cells with AFAP1-AS1 knockdown were injected into nude mice to investigate the effect of AFAP1-AS1 on tumorigenesis in vivo. Downregulation of AFAP1-AS1 suppressed tumor growth and inhibited the expression of EMT-related genes (SLUG, SNIAL1, VIM, ZEB1, NANOG, SMAD2, NESTIN and SOX2) in vivo.

Conclusions

Taken together, our findings present a road map for targeting the newly identified lncRNA AFAP1-AS1 to suppress TSCC progression, and these results elucidate a novel potential therapeutic strategy for TSCC.

Meta-analysis of the prognostic value of long non-coding RNA AFAP1-AS1 for cancer patients in China

LncRNA actin filament-associated protein 1 antisense RNA 1 (AFAP1-AS1) is often dysregulated in cancer. We performed this meta-analysis to clarify the usefulness of AFAP1-AS1 as a prognostic marker in malignant tumors. The PubMed, Medline, OVID, Cochrane Library, and Web of Science databases were searched from inception to Augest 7, 2017. Sixteen studies with a total of 1,386 patients were included in the study. The pooled hazard ratio (HR) suggested high AFAP1-AS1 expression correlated with poor overall survival (OS) (HR = 1.98, 95% confidence interval (CI): 1.71–2.28), disease-free survival (DFS) (HR = 1.54, 95% CI: 1.22–1.95), and progression-free survival (PFS) (HR = 2.17, 95% CI:1.64–2.88) in cancer patients, without obvious heterogeneity. High AFAP1-AS1 expression also correlated with larger tumor size (odds ratio (OR) = 2.04, 95% CI: 1.54–2.72), advanced tumor stage (OR=2.35, 95% CI: 1.70–3.26), poor histological grade (OR =1.39, 95% CI: 1.02–1.90), lymph node metastasis (OR = 2.71, 95% CI: 1.98–3.72) and distant metastasis (OR = 2.96, 95% CI: 2.03–4.32). Thus high AFAP1-AS1 expression is predictive of poor OS, DFS, PFS, lymph node metastasis, distant metastasis, histological grade, larger tumor size and tumor stage, which suggests high AFAP1-AS1 expression may serve as a novel biomarker of poor prognosis in cancer.

A long non-coding RNA signature for predicting survival in patients with colorectal cancer

Dysregulation of long non-coding RNA (lncRNA) plays important roles in cancer development and progression. In this work, we attempted to develop a lncRNA signature to improve prognosis prediction of colorectal cancer. A comprehensive analysis for the lncRNA expression and corresponding clinical information of 344 colorectal patients has been performed based on the data from The Cancer Genome Atlas (TCGA). We randomly divided TCGA data into a training set (n = 172) and a testing set (n = 172). A four-lncRNA signature has been established which was significantly associated with the overall survival of colorectal cancer patients. Based on the four-lncRNA signature, the training set can be classified into high-risk and low-risk groups with significantly different survival. The result can be further validated in the testing dataset and another independent dataset. Further analyses suggested that the prognostic power of the four-lncRNA signature was independent of other clinical variables. The identification of lncRNA signature indicated that lncRNAs could be novel independent biomarkers for predicting the survival in patients with colorectal cancer.

Regulation of EMT in Colorectal Cancer: A Culprit in Metastasis

Epithelial to mesenchymal transition (EMT) is a process during which cells lose their epithelial characteristics, for instance cell polarity and cell-cell contact, and gain mesenchymal properties, such as increased motility. In colorectal cancer (CRC), EMT is associated with an invasive or metastatic phenotype. In this review, we discuss recent studies exploring novel regulation mechanisms of EMT in CRC, including the identification of new CRC EMT regulators. Upregulation of inducers can promote EMT, leading to increased invasiveness and metastasis in CRC. These inducers can downregulate E-cadherin and upregulate N-cadherin and vimentin (VIM) through modulating EMT-related signaling pathways, for instance WNT/β-catenin and TGF-β, and EMT transcription factors, such as zinc finger E-box binding homeobox 1 (ZEB1) and ZEB2. In addition, several microRNAs (miRNAs), including members of the miR-34 and miR-200 families, are found to target mRNAs of EMT-transcription factors, for example ZEB1, ZEB2, or SNAIL. Downregulation of these miRNAs is associated with distant metastasis and advanced stage tumors. Furthermore, the role of EMT in circulating tumor cells (CTCs) is also discussed. Mesenchymal markers on the surface of EMT CTCs were found to be associated with metastasis and could serve as potential biomarkers for metastasis. Altogether, these studies indicate that EMT is orchestrated by a complicated network, involving regulators of different signaling pathways. Further studies are required to understand the mechanisms underlying EMT in CRC.

Survival prediction of kidney renal papillary cell carcinoma by comprehensive LncRNA characterization

Kidney renal papillary cell carcinoma (KIRP) accounts for 10%-15% of renal cell carcinoma (RCC), patients with KIRP tend to have a poor prognosis, and there was a lack of effective prognostic indicators for this type of cancer. Currently, owing to the availability of The Cancer Genome Atlas (TCGA), long non-coding RNAs (LncRNAs) have been discovered to indicate a prognostic value in some tumors. In that regard, we analyzed lncRNA-sequencing data of KIRP in TCGA, and among 780 differentially-expressed lncRNAs, we selected 37 lncRNAs which were able to assist the prognosis. In addition, by using the multivariate cox regression analysis, the prognosis index (PI) that consisted of 7 lncRNAs (including AFAP1-AS1, GAS6-AS1, RP11-1C8.7, RP11-21L19.1, RP11-503C24.1, RP11-536I6.2, and RP11-63A11.1) could predict the progression and outcomes of KIRP with accuracy. More importantly, the PI was considered an independent indicator for prognostication of KIRP. Moreover, having categorized patients with KIRP into cohorts of high risk and low risk, according to the PI, we found that the key genes and pathways varied in these two groups. Overall, these LncRNAs, especially the PI, may be conceived as biomarkers and helpful for determining the different pathological stages for KIRP patients. However, their biological functions need to be further confirmed.

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.

Overexpression long non-coding RNA LINC00673 is associated with poor prognosis and promotes invasion and metastasis in tongue squamous cell carcinoma

Long non-coding RNAs (lncRNAs) associated with the tumorigenesis of human cancers. However, the relevance of lncRNAs in tongue squamous cell carcinoma (TSCC) is still unclear. To discover novel TSCC-related lncRNAs, we analyzed the lncRNA expression patterns in two sets of TSCC gene expression profile data, and found that long intergenic non-coding RNA 673 (LINC00673) was significantly upregulated in TSCC samples. Then we examined LINC00673 expression in 202 TSCC tissue specimens, LINC00673 is highly expressed in a significant proportion of human TSCC biopsies and correlates with poor prognosis. Knockdown LINC00673 significantly inhibited the cell invasion and migration capability in TSCC cells. Our findings suggest that LINC00673 may play an essential role in TSCC progression and might serve as a potential biomarker for early detection and prognosis prediction of TSCC.

Long Noncoding RNA AFAP1-AS1 Promotes Cell Proliferation and Apoptosis of Gastric Cancer Cells via PTEN/p-AKT Pathway

BACKGROUND

Long noncoding RNA (lncRNA) plays critical roles in both tumor-suppressive and oncogenic pathways in the pathological development and prognosis of cancers.

AIMS

This study aimed to explore the expression of lncRNA AFAP1-AS1 and its function in gastric cancer (GC).

METHODS

The expression of AFAP1-AS1 was detected in GC tissues and GC cells by quantitative real-time reverse-transcription PCR. A small interfering RNA (siRNA) that targeted AFAP1-AS1 was transfected into cells to inhibit the expression of AFAP1-AS1. MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay and colony formation assay were performed to examine the cell proliferation of SGC7901 cell transfected with si-AFAP1-AS1. Cell apoptosis was detected by flow cytometry. The protein level of cleaved PARP, Caspase 3, Caspase 9, Caspase 8, Bcl-2, Bax, p-AKT, total-AKT, and PTEN were detected by Western blot.

RESULTS

AFAP1-AS1 was up-regulated in GC tissues and GC cells. AFAP1-AS1 knockdown suppressed cell viability of SGC7901 transfected with si-AFAP1-AS1. The number of apoptotic SGC7901 cell transfected with si-AFAP1-AS1 was increased by 3.4-fold comparing to that of control. The protein level of cleaved PARP, Caspase 3, and Caspase 9 were increased in SGC7901 transfected with si-AFAP1-AS1, as well as the expression of Bax. The protein level of Bcl-2 was decreased. AFAP1-AS1 knockdown decreased the protein level of p-AKT and increased the expression of PTEN in SGC7901 cells.

CONCLUSIONS

AFAP1-AS1 was up-regulated in GC cells and regulated the gastric cancer cell proliferation and apoptosis via PTEN/p-AKT pathway.

Long Noncoding RNAs as Biomarkers in Cancer

Long noncoding RNAs (lncRNAs) are a relatively well-characterized class of noncoding RNA (ncRNA) molecules, involved in the regulation of various cell processes, including transcription, intracellular trafficking, and chromosome remodeling. Their deregulation has been associated with the development and progression of various cancer types, the fact which makes them suitable as biomarkers for cancer diagnosis and prognosis. In recent years, detection of cancer-associated lncRNAs in body fluids of cancer patients has proven itself as an especially valuable method to effectively diagnose cancer. Cancer diagnosis and prognosis employing circulating lncRNAs are preferential when compared to classical biopsies of tumor tissues, especially due to their noninvasiveness, and have great potential for routine usage in clinical practice. Thus, this review focuses on summarizing the perspectives of lncRNAs as biomarkers in cancer, based on evaluating their expression profiles determined in body fluids of cancer patients.

Expression of long non-coding RNA PANDAR and its prognostic value in colorectal cancer patients

BACKGROUND

Long noncoding RNAs (lncRNAs) are emerging as key molecules in human cancer. In the present study, we explored the role of the lncRNA PANDAR in colorectal cancer (CRC).

METHODS

The relative expression level of lncRNA PANDAR in CRC tissues and cell lines was determined by quantitative real-time polymerase chain reaction (qRT-PCR). The associations between PANDAR expression and clinicopathological features of CRC patients were further analyzed. Kaplan-Meier survival analysis was performed to evaluate the value of PANDAR in the prognosis of CRC patients. Furthermore, the biological function of PANDAR on CRC cell growth, apoptosis and mobility was investigated through MTT, flow cytometry, transwell migration and invasion assays in vitro.

RESULTS

The expression level of PANDAR was higher in CRC tissues and cells compared with adjacent nontumor tissues and normal colonic cell line NCM460. PANDAR expression was significantly correlated with local invasion, lymph node metastasis and TNM stage. Kaplan-Meier analysis showed that patients with high PANDAR expression had poorer overall survival than patients with low PANDAR expression. Multivariate Cox regression analysis indicated that PANDAR might be an independent prognostic factor for CRC patients. Furthermore, PANDAR knockdown significantly inhibited cell proliferation, cycle progression, migration and invasion of CRC in vitro.

CONCLUSIONS

Our results suggest that high expression of PANDAR was involved in CRC progression and could act as an independent biomarker for prognosis of CRC patients.