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

Therapeutic advancements in targeting BCL-2 family proteins by epigenetic regulators, natural, and synthetic agents in cancer

Cancer is amongst the deadliest and most disruptive disorders, having a much higher death rate than other diseases worldwide. Human cancer rates continue to rise, thereby posing the most significant concerns for medical health professionals. In the last two decades, researchers have gone past several milestones in tackling cancer while gaining insight into the role of apoptosis in cancer or targeting various biomarker tools for prognosis and diagnosis. Apoptosis which is still a topic full of complexities, can be controlled considerably by B-cell lymphoma 2 (BCL-2) and its family members. Therefore, targeting proteins of this family to prevent tumorigenesis, is essential to focus on the pharmacological features of the anti-apoptotic and pro-apoptotic members, which will help to develop and manage this disorder. This review deals with the advancements of various epigenetic regulators to target BCL-2 family proteins, including the mechanism of several microRNAs (miRNAs) and long non-coding RNAs (lncRNAs). Similarly, a rise in natural and synthetic molecules' research over the last two decades has allowed us to acquire insights into understanding and managing the transcriptional alterations that have led to apoptosis and treating various neoplastic diseases. Furthermore, several inhibitors targeting anti-apoptotic proteins and inducers or activators targeting pro-apoptotic proteins in preclinical and clinical stages have been summarized. Overall, agonistic and antagonistic mechanisms of BCL-2 family proteins conciliated by epigenetic regulators, natural and synthetic agents have proven to be an excellent choice in developing cancer therapeutics.

Antisense long non-coding RNAs in gastric cancer

Gastric cancer is a global health problem with high mortality. The incidence of gastric cancer has significant regional differences. Helicobacter pylori (H. pylori) infection and its interaction with epigenetics are closely related to the occurrence of gastric cancer. It is of great significance to explore the early diagnosis and effective therapeutic targets of gastric cancer. Emerging evidence indicates that antisense long non-coding RNAs (lncRNAs) are closely associated with various biological and functional aspects of gastric cancer. However, diverse antisense lncRNAs in gastric cancer have not been compiled and discussed. In this review, we summarize the predisposing factors and compile the interaction between H. pylori and epigenetics in gastric cancer. Moreover, we focus on the underlying molecular mechanism and regulatory role of each antisense lncRNA in gastric cancer. In addition, we provide a new insight into the potential diagnosis and treatment of antisense lncRNAs in gastric cancer.

Long non-coding RNAs: Biogenesis, functions, and clinical significance in gastric cancer

Gastric cancer (GC) is one of the most prevalent malignant tumor types and the third leading cause of cancer-related death worldwide. Its morbidity and mortality are very high due to a lack of understanding about its pathogenesis and the slow development of novel therapeutic strategies. Long non-coding RNAs (lncRNAs) are a class of non-coding RNAs with a length of more than 200 nt. They play crucial roles in a wide spectrum of physiological and pathological processes by regulating the expression of genes involved in proliferation, differentiation, apoptosis, cell cycle, invasion, metastasis, DNA damage, and carcinogenesis. The aberrant expression of lncRNAs has been found in various cancer types. A growing amount of evidence demonstrates that lncRNAs are involved in many aspects of GC pathogenesis, including its occurrence, metastasis, and recurrence, indicating their potential role as novel biomarkers in the diagnosis, prognosis, and therapeutic targets of GC. This review systematically summarizes the biogenesis, biological properties, and functions of lncRNAs and highlights their critical role and clinical significance in GC. This information may contribute to the development of better diagnostics and treatments for GC.

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.

Silencing of LncRNA AFAP1-AS1 Inhibits Cell Proliferation in Oral Squamous Cancer by Suppressing CCNA2

Background

Evidence has indicated that dysregulation of long noncoding RNAs (lncRNA) is a critical factor in the occurrence of many diseases, including cancer. The lncRNA AFAP1-AS1 has been shown to participate in oncogenesis, metastasis, or drug resistance in many types of cancer. However, the potential role of AFAP1-AS1 in oral squamous cell carcinoma (OSCC) has not been fully elucidated.

Methods

Bioinformatics analysis was performed to compare AFAP1-AS1 expression levels in OSCC cancer samples and in normal controls. The biological function of AFAP1-AS1 was studied through loss-of-function assays. To study the potential mechanisms, high-throughput sequencing was applied to OSCC cancer samples and a series of bioinformatics analyses were performed. The effects of AFAP1-AS1 on OSCC tumor growth was evaluated by in vivo xenograft tumor formation assays.

Results

Bioinformatics analyses indicated that AFAP1-AS1 was upregulated in OSCC. Overexpression of AFAP1-AS1 was positively correlated with lymph node metastasis, tumor stage, and pathological grade. Down-regulation of AFAP1-AS1 in OSCC led to decreased proliferation in vitro and, notably, inhibition of tumor growth in vivo. Further research indicated that AFAP1-AS1 regulated OSCC cell proliferation by targeting CCNA2.

Conclusion

AFAP1-AS1 promotes tumor proliferation and indicates a poor prognosis in OSCC, providing a potential therapeutic strategy.

Integrated analysis of mRNA and long non-coding RNA expression profiles reveals the potential roles of lncRNA-mRNA network in carp macrophage immune regulation

Long non-coding RNAs (lncRNAs) have emerged as a hot topic in research as mounting evidence has indicated their transcriptional or post-transcriptional regulatory potential in multiple biological processes. Previous studies have revealed the involvement of lncRNAs in the immunoregulation of mammalian macrophages by changing mRNA expression; however, studies on the lncRNAs in fish macrophages and their potential roles in the immune system remain unknown. Primary macrophages were isolated from the head kidney (HK) of red common carp (Cyprinus carpio) and high-throughput lncRNA-mRNA sequencing was performed using the Illumina HiSeq platform. The results revealed that the most highly expressed mRNAs in primary HK macrophages were mainly involved in immune-related signal pathways. Furthermore, the most enriched immune-related GO term and KEGG pathway of the mRNAs were "immune system development" and "chemokine signaling pathway," respectively. A total of 20,333 lncRNAs, composed of 10,512 known and 9821 novel lncRNAs, were identified, and functional enrichment analysis of the lncRNA-mRNA network indicated that the expressed lncRNAs in primary HK macrophages could be associated with the regulation of multiple immune-related signaling pathways. In addition, the expressions of several selected lncRNAs and their related mRNAs were determined in carp macrophages following a 6-h exposure to lipopolysaccharide (LPS) and Poly(I: C), the results of which confirmed the co-expression regulation of lncRNAs and target mRNAs in the immune response of carp macrophages. These results suggest the correlative of the lncRNA-mRNA network in fish macrophage immune response, which may further affect the cross-talk of various signaling pathways by interaction with other network genes. Here, we provided fundamental data about the transcriptome profiles of primary HK macrophages from red common carp by analysis of the lncRNA-mRNA network, and ultimately suggest the potential roles of lncRNA-mRNA networks in immune regulation in teleost fish.

Long non-coding RNAs and microorganism-associated cancers

Cancerous cells are abnormal cells characterized by aberrant growth and proliferation, which can involve various types of cells and tissues. Through numerous signalling pathways, many mechanisms are involved in cells that keep them normal. These signalling pathways are tightly set by different proteins whose expression is regulated by a large number of factors. In other words, when a regulating factor does not act properly or undergoes a change in its function or expression, the result will be that the subordinate gene and subsequently the related protein will show deranged expression and activity. This leads to disordered signalling pathways which bring about uncontrolled proliferation in cells. One of the most significant factors in adjusting the expression of genes is noncoding RNAs. It should be noted that all underlying causes initiating malignancy try to alter the main regulatory factors in cellular processes and gene expression and direct the cell to an unregulated state. Microorganisms have been identified as one of the important elements to direct normal cells to abnormality. That is, they probably agitate the malignant traits through manipulating significant factors such as ncRNAs in given cells using their own or host-related factors. The present study is aimed at examining how the long noncoding RNAs are involved in microorganism-mediated cancers.

lncRNAs as Hallmarks for Individualized Treatment of Gastric Cancer

Gastric cancer is global cancer with a high mortality rate. A growing number of studies have found the abnormal expression of lncRNA (long noncoding RNA) in many tumors, which plays a role in promoting or inhibiting cancer. Similarly, lncRNA abnormal expression plays an essential biological function in gastric cancer. This article focuses on lncRNA involvement in the development of gastric cancer in terms of cell cycle disorder, apoptosis inhibition, metabolic remodeling, promotion of tumor inflammation, immune escape, induction of angiogenesis, and epithelial mesenchymal transition (EMT). The involvement of lncRNA in the development of gastric cancer is related to drug resistance, such as cisplatin and multi-drug resistance. It can also be used as a potential marker for the diagnosis and prognosis of gastric cancer and a target for the treatment. With an in-depth understanding of the mechanism of lncRNA in gastric cancer, new ideas for personalized treatment of gastric cancer are expected.

LncRNA AFAP1-AS1 Modulates the Proliferation and Invasion of Gastric Cancer Cells by Regulating AFAP1 via miR-205-5p

Purpose

The present study investigated the expression and function of the long noncoding RNA (lncRNA) actin filament associated protein 1 antisense RNA1 (AFAP1-AS1) related to gastric cancer (GC), based on previous results from a microarray analysis.

Methods

Real-time quantitative polymerase chain reaction (qPCR) was used to verify the expression of AFAP1-AS1 in 97 fresh GC tissues and paired non-GC tissues, as well as in six different GC cell lines (BGC-823, SGC-7901, MGC-803, AGS, MKN-45, and MKN-28). The expression levels were subsequently correlated with the clinicopathological features of patients. siRNA against AFAP1-AS1 was transfected into GC cell lines, and cell proliferation, migration, and invasion were detected before and after silencing of AFAP1-AS1 expression. Luciferase reporter gene analysis was used to confirm the target gene of microRNA-205-5p (miR-205-5p) in 293T cells. The potential mechanism was subsequently investigated.

Results

qPCR results showed that AFAP1-AS1 was significantly overexpressed in GC tumor tissues and also GC cell lines, comparing to their paired non-GC tissues. Furthermore, statistical analysis revealed that the overexpression of AFAP1-AS1 was significantly correlated with tumor size (p=0.018) and grade of differentiation (p=0.042). Subsequently, artificially decreasing the expression of AFAP1-AS1 with its specific siRNA dramatically inhibited the proliferation, migration and invasion of GC cell lines (SGC-7901 and BGC-823 cells). Mechanical analysis suggested that AFAP1-AS1 is involved in regulation of its maternal gene, AFAP1, at both mRNA level and protein level. Luciferase reporter gene assay indicated that lncRNA AFAP1-AS1, as a ceRNA, is able to sponge miR-205-5p. Moreover, miR-205-5p has been well demonstrated to participate in the regulation of AFAP1 expression and the phenotypes of GC cells, including proliferation, migration and invasion.

Conclusion

AFAP1-AS1, as a novel biomarker of GC, promotes the proliferation migration and invasion of GC cells and function as ceRNA to target AFAP1 by sponging miR-205-5p.

Long noncoding RNA AFAP1-AS1 promotes tumor progression and invasion by regulating the miR-2110/Sp1 axis in triple-negative breast cancer

Long noncoding ribonucleic acids (LncRNAs) have been found to be involved in the proliferation, apoptosis, invasion, migration, and other pathological processes of triple-negative breast cancer (TNBC). Expression of the lncRNA actin filament-associated protein 1 antisense RNA1 (AFAP1-AS1) has been found to be significantly higher in TNBC than in other subtypes or in normal tissue samples, but the specific mechanism by which AFAP1-AS1 affects the occurrence and development of TNBC is yet to be revealed. In this study, we used Cell Counting Kit-8 (CCK-8), colony formation, wound healing migration, Transwell invasion, and nude mouse xenograft assays to confirm the role of AFAP1-AS1 in the proliferation, migration of TNBC cells in vitro and in vivo. In addition, we performed bioinformatics analyses, reverse transcriptase quantitative polymerase chain reaction (RT-qPCR), western blot (WB), and dual-luciferase reporter assays (dual-LRA) to confirm interaction among AFAP1-AS1, micro-RNA 2110 (miR-2110), and Sp1 transcription factor (Sp1). We found that silencing AFAP1-AS1 and Sp1 or upregulating miR-2110 suppressed the proliferation, migration, and invasion of MDA-MB-231 and MDA-MB-468 cells in vitro as well as tumor growth in vivo. Mechanistically, the dual-LRA highlighted that miR-2110 was an inhibitory target of AFAP1-AS1, and that AFAP1-AS1 functioned as a miR-2110 sponge to increase Sp1 expression. AFAP1-AS1 silencing led to a reduction in Sp1 mRNA and protein levels, which could be reversed by joint transfection with miR-2110 inhibitor. Our findings demonstrated that AFAP1-AS1 could modulate the progression of breast cancer cells and affect tumorigenesis in mice by acting as a miR-2110 sponge, resulting in regulation of Sp1 expression. Therefore, AFAP1-AS1 could play a pivotal role in the treatment of TNBC.

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 AFAP1‑AS1 facilitates the growth and invasiveness of oral squamous cell carcinoma by regulating the miR‑145/HOXA1 axis

Long non-coding RNA (lncRNA) actin filament-associated protein 1 antisense RNA 1 (AFAP1-AS1) has been reported to serve important roles in multiple types of cancer. However, the biological function and underlying mechanism of AFAP1-AS1 in oral squamous cell carcinoma (OSCC) remain largely unknown. The present study aimed to investigate the biological roles and clarify the potential mechanism of AFAP1-AS1 in OSCC. The expression levels of AFAP1-AS1 in OSCC tissues and cells were determined using reverse transcription-quantitative PCR. Cell proliferation, colony formation, migration and invasion were analyzed using Cell Counting Kit-8, colony formation, wound healing and Transwell invasion assays, respectively. The potential binding between AFAP1-AS1 and microRNA (miR)-145 was validated using dual luciferase reporter and RNA pull-down assays. A xenograft tumor model was established to evaluate the effect of AFAP1-AS1 in vivo. The results revealed that AFAP1-AS1 expression levels were markedly upregulated in OSCC tissues and cells. In addition, patients with OSCC with high expression levels of AFAP1-AS1 had a poor prognosis. Functionally, the knockdown of AFAP1-AS1 in OSCC cells significantly inhibited cell proliferation, migration and invasion in vitro. Similarly, in vivo AFAP1-AS1 knockdown prevented tumor growth and reduced tumor size and weight. Mechanistically, AFAP1-AS1 was discovered to regulate the expression levels of Homeobox A1 (HOXA1) by competing with miR-145. The inhibition of miR-145 partially attenuated the inhibitory effects of AFAP1-AS1 knockdown on OSCC cells. In conclusion, the findings of the present study suggested that AFAP1-AS1 may promote the progression of OSCC by regulating the miR-145/HOXA1 axis.

PI3K/AKT/mTOR signaling in gastric cancer: Epigenetics and beyond

PI3K/AKT/mTOR pathway is one of the most important signaling pathways involved in normal cellular processes. Its aberrant activation modulates autophagy, epithelial-mesenchymal transition, apoptosis, chemoresistance, and metastasis in many human cancers. Emerging evidence demonstrates that some infections as well as epigenetic regulatory mechanisms can control PI3K/AKT/mTOR signaling pathway. In this review, we focused on the role of this pathway in gastric cancer development, prognosis, and metastasis, with an emphasis on epigenetic alterations including DNA methylation, histone modifications, and post-transcriptional modulations through non-coding RNAs fluctuations as well as H. pylori and Epstein-Barr virus infections. Finally, we reviewed different molecular targets and therapeutic agents in clinical trials as a potential strategy for gastric cancer treatment through the PI3K/AKT/mTOR pathway.

Status of kinases in Epstein-Barr virus and Helicobacter pylori Coinfection in gastric Cancer cells

BACKGROUND

Helicobacter pylori (H. pylori) and Epstein - Barr virus (EBV) plays a significant role in aggressive gastric cancer (GC). The investigation of genes associated with these pathogens and host kinases may be essential to understand the early and dynamic progression of GC.

AIM

The study aimed to demonstrate the coinfection of EBV and H. pylori in the AGS cells through morphological changes, expression of the kinase and the probable apoptotic pathways.

METHODS

Genomic DNA isolation of H. pylori and its characterization from clinical samples were performed. RT-qPCR of kinases was applied to scrutinize the gene expression of kinases in co-infected GC in a direct and indirect (separated through insert size 0.45 μm) H. pylori infection set up. Morphological changes in co-infected GC were quantified by measuring the tapering ends of gastric epithelial cells. Gene expression profiling of apoptotic genes was assessed through RT-qPCR.

RESULTS

An interleukin-2-inducible T-cell kinase (ITK) showed significant upregulation with indirect H. pylori infection. Moreover, Ephrin type-B receptor six precursors (EPHB6) and Tyrosine-protein kinase Fyn (FYN) showed significant upregulation with direct coinfection. The tapering ends in AGS cells were found to be extended after 12 h. A total of 24 kinase genes were selected, out of which EPHB6, ITK, FYN, and TYK2 showed high expression as early as 12 h. These kinases may lead to rapid morphological changes in co-infected gastric cells. Likewise, apoptotic gene expression such as APAF-1 and Bcl2 family genes such as BAD, BID, BIK, BIM, BAX, AND BAK were significantly down-regulated in co-infected AGS cells.

CONCLUSION

All the experiments were performed with novel isolates of H. pylori isolated from central India, for the functional assessment of GC. The effect of coinfection with EBV was more profoundly observed on morphological changes in AGS cells at 12 h as quantified by measuring the tapering of ends. This study also identifies the kinase and apoptotic genes modulated in co-infected cells, through direct and indirect approaches. We report that ITK, EPHB6, TYK2, FYN kinase are enhanced, whereas apoptotic genes such as APAF-1, BIK, FASL, BAX are significantly down-regulated in AGS cells coinfected with EBV and H. pylori.

PTEN, a Barrier for Proliferation and Metastasis of Gastric Cancer Cells: From Molecular Pathways to Targeting and Regulation

Cancer is one of the life-threatening disorders that, in spite of excellent advances in medicine and technology, there is no effective cure for. Surgery, chemotherapy, and radiotherapy are extensively applied in cancer therapy, but their efficacy in eradication of cancer cells, suppressing metastasis, and improving overall survival of patients is low. This is due to uncontrolled proliferation of cancer cells and their high migratory ability. Finding molecular pathways involved in malignant behavior of cancer cells can pave the road to effective cancer therapy. In the present review, we focus on phosphatase and tensin homolog (PTEN) signaling as a tumor-suppressor molecular pathway in gastric cancer (GC). PTEN inhibits the PI3K/Akt pathway from interfering with the migration and growth of GC cells. Its activation leads to better survival of patients with GC. Different upstream mediators of PTEN in GC have been identified that can regulate PTEN in suppressing growth and invasion of GC cells, such as microRNAs, long non-coding RNAs, and circular RNAs. It seems that antitumor agents enhance the expression of PTEN in overcoming GC. This review focuses on aforementioned topics to provide a new insight into involvement of PTEN and its downstream and upstream mediators in GC. This will direct further studies for evaluation of novel signaling networks and their targeting for suppressing GC progression.

LncRNA AFAP1-AS1 contributes to the progression of endometrial carcinoma by regulating miR-545-3p/VEGFA pathway

Endometrial carcinoma (EC) accounts for 20%-30% of female reproductive tumors. Targeted therapy for EC has shown great advantages with small side effects. To improve the survival of EC patients, more new therapeutic targets need to be found. Long non-coding RNAs (lncRNAs) are series of RNAs with over 200 nucleotides that regulate various cellular functions. LncRNA actin filamentin-1 antisense RNA 1 (AFAP1-AS1) is involved in the development of a variety of cancers, such as pancreas ductal adenocarcinoma and esophageal adenocarcinoma. However, it is not clear whether AFAP1-AS1 has any effects on EC or the exact regulatory mechanism. Herein, we found the high expression of AFAP1-AS1 in human EC tissues, and AFAP1-AS1 was correlated with EC patients' prognosis and clinical features. AFAP-AS1 could affect EC cell proliferation, migration, and invasion, and contributed to endothelial cell angiogenesis. We further showed that AFAP-AS1 could promote the expression of VEGFA through the adsorption of miR-545-3p, thus promoting the angiogenesis and invasion of EC, and contribute to tumor growth and metastasis in vivo. Thus, we thought AFAP1-AS1 had the potential to serve as an EC therapeutic target.

Non-coding RNAs in drug resistance of head and neck cancers: A review

Head and neck cancer (HNC), which includes epithelial malignancies of the upper aerodigestive tract (oral cavity, oropharynx, pharynx, hypopharynx, larynx, and thyroid), are slowly but consistently increasing, while the overall survival rate remains unsatisfactory. Because of the multifunctional anatomical intricacies of the head and neck, disease progression and therapy-related side effects often severely affect the patient's appearance and self-image, as well as their ability to breathe, speak, and swallow. Patients with HNC require a multidisciplinary approach involving surgery, radiation therapy, and chemotherapeutics. Chemotherapy is an important part of the comprehensive treatment of tumors, especially advanced HNC, but drug resistance is the main cause of poor clinical efficacy. The most important determinant of this phenomenon is still largely unknown. Recent studies have shown that non-coding RNAs have a crucial role in HNC drug resistance. In addition, they can serve as biomarkers in the diagnosis, treatment, and prognosis of HNCs. In this review, we summarize the relationship between non-coding RNAs and drug resistance of HNC, and discuss their potential clinical application in overcoming HNC chemoresistance.

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.

Oral rinses in growth inhibition and treatment of Helicobacter pylori infection

BACKGROUND

Helicobacter pylori (H. pylori) is well-known for its role in chronic gastritis and gastric cancer. Eradication of these carcinogenic bacteria from the gut is one of the challenges for clinicians. The complexity of treatment mainly owes to antibiotic resistance and relapse due to an additional reservoir in the oral cavity. Our study emphases the isolation of H. pylori from distinct habitats of the gut microenvironment (gastric biopsy and gastric juice) and its subsequent characterization. We have also evaluated the effect of various oral rinses on isolated H. pylori from different anatomical locations of included subjects.

RESULTS

The possible strains isolated from two different habitats of the same subject shows a striking difference in their growth pattern. Promisingly, some of the included oral rinses are efficient in growth inhibition as per recommended 30 s treatment. The subsequent evaluation shows that oral rinse B (among A-E) is most effective and down-regulates the expression of one of the potent H. pylori gene, CagA, in the infected gastric adenocarcinoma (AGS) cells.

CONCLUSION

Our study, for the first time, revealed that H. pylori, isolated from the different habitat of the same subject, show a different growth pattern. The expression of H. pylori pathogenic gene (CagA) was down-regulated by the use of oral rinses. Hence, oral rinses will reduce the H. pylori in the oral cavity and help to control its migration from oral to the gastric compartment and may be used as an adjuvant treatment option for its re-infection.

Long Noncoding RNA AFAP1-AS1 Promotes Cell Proliferation and Metastasis via the miR-155-5p/FGF7 Axis and Predicts Poor Prognosis in Gastric Cancer

Background

Actin filament-associated protein 1-antisense RNA 1 (AFAP1-AS1) plays an important role in the development and progression of several human cancers. However, its biological function in gastric cancer (GC) progression is still unknown.

Methods

We used qRT-PCR to detect the relative expression of AFAP1-AS1 in GC tissues and cell lines. The loss-of-function assays were conducted to detect the effect of AFAP1-AS1 on GC development. Bioinformatics analysis, luciferase reporter gene analysis, and RIP analysis were used to identify and validate target genes of AFAP1-AS1. Finally, rescue tests were performed to confirm the influence of the AFAP1-AS1-miR-155-5p-FGF7 axis on GC development.

Results

AFAP1-AS1 was upregulated in GC tissues and cell lines and was closely correlated with poor prognosis of GC patients. AFAP1-AS1 knockdown inhibited proliferation, migration, and invasion of GC cells, indicating that AFAP1-AS1 acts as an oncogene in GC. Bioinformatics analysis, dual-luciferase reporter gene detection, and RIP assays validated that AFAP1-AS1 directly interacts to miR-155-5p and could positively affect cell proliferation, migration, and invasion by regulation of the expression of miR-155-5p and FGF7. Further rescue assays revealed that AFAP1-AS1 promotes cell proliferation and metastasis through the miR-155-5p/FGF7 axis in GC.

Conclusions

AFAP1-AS1 might be an oncogenic lncRNA that promoted GC progression by acting as a competing endogenous RNA (ceRNA) that regulates the expression of FGF7 through sponging miR-155-5p, suggesting that AFAP1-AS1 may be a novel potential therapeutic target for GC.

Long non-coding RNA signature in gastric cancer

Gastric cancer as a common human malignancy has been associated with aberrant expressions of several coding and non-coding genes. Long non-coding RNAs (lncRNAs) as regulators of gene expressions at different genomic, transcriptomic and post-transcriptomic levels are among putative biomarkers and therapeutic targets in gastric cancer. In the present study, we have searched available literature and listed lncRNAs that are involved in the pathogenesis of gastric cancer. In addition, we discuss associations between expressions of these lncRNAs and tumoral features or risk factors for gastric cancer. Based on the established role of lncRNAs in regulation of genomic stability, cell cycle, apoptosis, angiogenesis and other aspects of cell physiology, the potential of these transcripts as therapeutic targets in gastric cancer should be evaluated in future studies.

AFAP1-AS1 induces cisplatin resistance in non-small cell lung cancer through PI3K/AKT pathway

Cisplatin (DDP)-resistance in non-small cell lung carcinoma (NSCLC) severely influences the prognosis of affected patients. This study aims to uncover the potential role of AFAP1-AS1 in DDP-resistant NSCLC and the underlying mechanism. The expression level of AFAP1-AS1 in DDP-resistant NSCLC patients and DDP-resistant A549 cells (A549/DDP) was determined. Proliferative, cell cycle distribution, apoptotic, migratory and invasive changes in A549/DDP cells transfected with si-AFAP1-AS1 were assessed. Western blot analyses were conducted to examine the protein levels of phosphorylated protein kinase B (p-AKT), AKT, E-cadherin, N-cadherin, vimentin and snail in A549/DDP cells. Furthermore, the ubcellular distribution of AFAP1-AS1 was analyzed. Through RNA immunoprecipitation (RIP) assay, the interaction between AFAP1-AS1 and enhancer of zeste homolog 2 (EZH2) was explored. Finally, the regulatory effect of EZH2 on the PI3K/AKT pathway was investigated by western blot analysis. AFAP1-AS1 was upregulated in DDP-resistant NSCLC patients and A549/DDP cells. Transfection with si-AFAP1-AS1 attenuated the proliferative, migratory and invasive abilities, arrested cell cycle in G0/G1 phase, and stimulated apoptosis of A549/DDP cells. Silencing of AFAP1-AS1 upregulated E-cadherin and downregulated N-cadherin, vimentin and snail expression levels. Furthermore, AFAP1-AS1 was verified to interact with EZH2. The relative expression of EZH2 was reduced by transfection of A549/DDP cells with si-AFAP1-AS1. Silencing of EZH2 inhibited the activation of PI3K/AKT pathway. In conclusion, AFAP1-AS1 accelerates the proliferative and metastatic abilities of A549/DDP cells, whereas inhibits the apoptosis of A549/DDP cells, by interacting with EZH2 to activate the PI3K/AKT pathway; thus, inducing DDP resistance in NSCLC.

LncRNA MEG3 influences the proliferation and apoptosis of psoriasis epidermal cells by targeting miR-21/caspase-8

Background

It was reported that microRNA-21(miR-21) was differentially expressed in the keratinocytes of psoriasis patients, and it may influence the apoptosis and proliferation of cells. The role of lncRNA maternally expressed gene3 (MEG3), a competing endogenous RNAs of miR-21, in the progression of psoriasis remains unclear. We aimed to unfold the influence of MEG3 and miR-21 on the proliferation and apoptosis of psoriasis epidermal cells.

Methods

50μg/L TNF-α was used to treat HaCaTs and NHEKs cells for 24 h, and then different experiments were conducted. qRT-PCR were applied for measuring the mRNA level of MEG3, miR-2, and caspase-8, and the protein expression of caspase-8 was measured with western blotting. Flow cytometry was used for assessing apoptosis. Cell proliferation was detected using MTT and colony formation assays. Dual luciferase reporter assay was applied for confirming the binding site between MEG3 and miR-21, miR-21 and Caspase-8.

Results

A cell model for in vitro studying the role of MEG3 in psoriasis pathophysiology was established using HaCaT and HHEKs. MEG3 was significantly down-regulated in HaCaT, HHEKs, and psoriatic skin samples. MEG3 inhibits proliferation and promotes apoptosis of Activated-HaCaT (Act-HaCaT) and Activated-HHEKs (Act- HHEK) by regulating miR-21, and the binding site between MEG3 and miR-21 was identified. We also found that miR-21 could inhibit the level of caspase-8 and identified the binding site between caspase-8 and miR-21. Some down-stream proteins of caspase-8, Cleaved caspase-8, cytc, and apaf-1 were regulated by miR-21 and MEG3.

Conclusion

MEG3/miR-21 axis may regulate the expression of caspase-8, and further influence the proliferation and apoptosis of psoriasis keratinocyte, Act-HaCaT and Act- HHEK. Therefore, our findings may provide a new thought for the study of pathogenesis and treatment of psoriasis.

Long noncoding RNA DINO (damage induced noncoding) represses the development of gastric cancer by modulating p21 and Bcl-2 Associated X Protein (Bax) expression

lncRNAs are responsible for a variety of diseases, including gastric cancer (GC). Many recent studies have reported that lncRNAs can serve as crucial regulators of various genes. Nevertheless, the biological function of lncRNA damage induced noncoding (DINO) remained poorly investigated in GC. Therefore, in our present study, the detailed role of DINO was investigated. It was manifested that DINO was significantly downregulated in GC tissues. Then, DINO was modulated by infecting LV-DINO or by LV-shRNA in BGC-823 and MGC-803 cells. Moreover, it was displayed that GC cell proliferation was suppressed by DINO overexpression, whereas silencing DINO increased cell proliferation significantly. For another, it was indicated that DINO dramatically induced apoptotic ratios of BGC-823 and MGC-803 cells, whereas the decrease of DINO depressed GC cell apoptosis. Apart from these, GC cell cycle progression was greatly blocked by LV-DINO. Furthermore, Western blot results displayed that upregulation of DINO elevated p21 expression and Bax expression. Oppositely, inhibition of DINO greatly suppressed p21 and Bax protein expression level. Taken these, DINO might exert a tumor inhibitory role in the progression of GC through modulating p21 and Bax.

Roles of E-cadherin and Noncoding RNAs in the Epithelial-mesenchymal Transition and Progression in Gastric Cancer

The epithelial–mesenchymal transition (EMT) is thought to be at the root of invasive and metastatic cancer cell spreading. E-cadherin is an important player in this process, which forms the structures that establish and maintain cell–cell interactions. A partial or complete loss of E-cadherin expression in the EMT is presumably mediated by mechanisms that block the expression of E-cadherin regulators and involve the E-cadherin-associated transcription factors. The protein is involved in several oncogenic signaling pathways, such as the Wnt/β-catenin, Rho GTPase, and EGF/EGFR, whereby it plays a role in many tumors, including gastric cancer. Such noncoding transcripts as microRNAs and long noncoding RNAs—critical components of epigenetic control of gene expression in carcinogenesis—contribute to regulation of the E-cadherin function by acting directly or through numerous factors controlling transcription of its gene, and thus affecting not only cancer cell proliferation and metastasis, but also the EMT. This review focuses on the role of E-cadherin and the non-coding RNAs-mediated mechanisms of its expressional control in the EMT during stomach carcinogenesis.

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.

Silencing of lncRNA AFAP1-AS1 Inhibits Cell Growth and Metastasis in Clear Cell Renal Cell Carcinoma

The lncRNA AFAP1-AS1, oriented from an antisense direction to the protein-coding gene AFAP1 in the opposite strand, was upregulated in a variety of tumors and associated with poor prognosis, including lung cancer, breast cancer, ovarian cancer, and so on. However, the biological role of AFAP1-AS1 in clear cell renal cell carcinoma (ccRCC) is still unknown. We observed that AFAP1-AS1 expression was significantly upregulated in ccRCC tissues and that patients with high-level expression of AFAP1-AS1 had a shorter overall survival. Knockdown of AFAP1-AS1 markedly suppressed the progression of proliferation, invasion, migration, and EMT in ccRCC cells. Downregulation of AFAP1-AS1 resulted in an increase in E-cadherin and a decrease in vimentin. Noticeably, we found that PTEN has a negative correlation with the lncRNA AFAP1-AS1 expression. Further studies verified that PTEN deficiency effectively attenuated the ability of AFAP1-AS1 in promoting ccRCC cell proliferation, invasion, migration, and EMT. Moreover, the similar biological response of silencing AFAP1-AS1 was observed in our ccRCC mice model. Knockdown of AFAP1-AS1 evidently suppressed tumor growth. Taken together, our results provide the evidences that silencing of AFAP1-AS1 inhibits cell proliferation, EMT, and metastasis through PTEN-dependent signaling, and our findings elucidate a novel potential therapeutic target or biomarker for the treatment of ccRCC.

Role of abnormal microRNA expression in Helicobacter pylori associated gastric cancer

Epidemiological studies have shown that Helicobacter pylori (HP) infection is a risk factor for gastric cancer (GC). HP infection may induce the release of pro-inflammatory mediators, and abnormally increase the level of reactive oxygen species (ROS), nitric oxide (NO), and cytokines in mucosal epithelial cells of the stomach. However, the specific mechanism underlying the pathogenesis of HP-associated GC is still poorly understood. Recent studies have revealed that abnormal microRNA expression may affect the proliferation, differentiation, and apoptosis of mucosal epithelial cells of the stomach to further influence GC occurrence, development, and metastasis. Herein, we summarize the role of abnormal microRNAs in the regulation of HP-associated GC progression. Abnormal microRNA expression in HP-positive GC may be a biomarker for GC diagnosis, occurrence, and development as well as its targeted treatment and prognosis.

Cloning and characterization of the putative AFAP1-AS1 promoter region

Actin filament-associated protein 1-antisense RNA1 (AFAP1-AS1), a cancer-related long non-coding RNA, has been found to be upregulated in multiple types of cancers. AFAP1-AS1 is important for the initiation, progression and poor prognosis of many cancers, including nasopharyngeal carcinoma (NPC). However, the mechanism underlying the regulation of AFAP1-AS1 expression is not well-understood. In our study, the potential promoter region of AFAP1-AS1 was predicted by comprehensive bioinformatics analysis. Moreover, promoter deletion analysis identified the sequence between positions -359 and -28 bp as the minimal promoter region of AFAP1-AS1. The ChIP assay results indicate that the AFAP1-AS1 promoter is responsive to the transcription factor c-Myc, which can promote high AFAP1-AS1 expression. This study is the first to clone and characterize the AFAP1-AS1 promoter region. Our findings will help to better understand the underlying mechanism of high AFAP1-AS1 expression in tumorigenesis and to develop new strategies for therapeutic high expression of AFAP1-AS1 in NPC.

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.

Long noncoding RNA HOTAIRM1 inhibits cell progression by regulating miR-17-5p/ PTEN axis in gastric cancer

OBJECTIVES

This study was conducted to identify the significantly altered long noncoding RNAs (lncRNAs), messenger RNA (mRNA) and pathways in gastric cancer (GC).

METHODS

We used microarray analysis to identify differentially expressed lncRNAs and mRNAs, whereas the obviously changed pathways were found by gene set enrichment analysis. The coexpression network of lncRNA and mRNA was constructed by Cytoscape, and their target relationships with miRNAs were predicted by miRcode and TargetScan. qRT-PCR and Western blot were performed to determine the expression levels of mRNAs and proteins in tissues and cell lines. Dual-luciferase reporter assay was applied to achieve the determination of the specific target relationships. Cell viability, migration, and apoptosis were detected by MTT assay, wound healing assay and flow cytometry, respectively. Through the xenograft assay, the gastric tumor was implanted into nude mice to investigate the influence of HOTAIRM1 in vivo.

RESULTS

HOTAIRM1 and phosphatase and tensin homolog (PTEN) were both downregulated in GC, whereas miR-17-5p was upregulated. Moreover, the PI3K/AKT pathway was found activated in GC. HOTAIRM1 targeted miR-17-5p, whereas PTEN was the downstream target gene of miR-17-5p. HOTAIRM1 suppressed proliferation and migration of GC cell line and induced their apoptosis, whereas miR-17-5p played the opposite role on GC cell line. HOTAIRM1 also postponed tumor growth in vivo and inhibited the PI3K/AKT pathway in GC.

CONCLUSIONS

LncRNA HORAIRM1 suppressed the PI3K/AKT pathway in GC and inhibited the progression of GC by serving as a competing endogenous RNA of miR-17-5p, mediating the expression of PTEN.

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.

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 non-coding RNA-mediated regulation of signaling pathways in gastric cancer

Gastric cancer (GC) is one of the most common cancers globally. Because of the high frequency of tumor recurrence, or metastasis, after surgical resection, the prognosis of patients with GC is poor. Therefore, exploring the mechanisms underlying GC is of great importance. Recently, accumulating evidence has begun to show that dysregulated long non-coding RNAs (lncRNAs) participate in the progression of GC via several typical signaling pathways, such as the AKT and MAPK signaling pathways. Moreover, the interactions between lncRNAs and microRNAs appear to represent a novel mechanism in the pathogenesis of GC. This review provides a synopsis of the latest research relating to lncRNAs and associated signaling pathways in GC.

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 non-coding RNAs: crucial regulators of gastrointestinal cancer cell proliferation

Studies of long non-coding RNAs (lncRNAs) have been prevalent in the field of non-coding RNA regulation in recent years. LncRNAs exert crucial effects on malignant cell processes in the gastrointestinal system, including proliferation. Aberrant lncRNA expression, through both oncogenes and tumor suppressor genes, is instrumental to tumor cell proliferation. Here, we summarize the different molecular mechanisms and relevant signaling pathways through which multifarious lncRNAs regulate cell proliferation and we show that lncRNAs are potential biomarkers for gastrointestinal cancers.

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.

HIF‑1α‑induced upregulation of lncRNA UCA1 promotes cell growth in osteosarcoma by inactivating the PTEN/AKT signaling pathway

Increasing evidence indicates that long non-coding RNAs (lncRNAs) play an important role in multiple biological processes including cell growth, differentiation, proliferation and invasion. Urothelial carcinoma associated 1 (UCA1) is a highly conserved nuclear ncRNA and a key regulator of cell proliferation and apoptosis in several types of cancers. However, its role in osteosarcoma progression is not well known. In the present study, we aimed to determine the biological role of UCA1 in osteosarcoma progression. RT-qPCR analysis showed that UCA1 expression was significantly increased in osteosarcoma cell lines and promoted cell growth in osteosarcoma. We then sought to determine the mechanism underlying the upregulation of UCA1 in osteosarcoma. Luciferase reporter assay and chromatin immunoprecipitation assay suggested that lncRNA UCA1 was induced by HIF-1α and HIF-1α interacts with the HIF-1α response element in the promoter region of UCA1. In addition, the gain- and loss-of-functional assay showed that HIF-1α promoted osteosarcoma cell growth through inducing the UCA1 expression level. More importantly, Cignal Signal Transduction Reporter Array and western blot assay showed that lncRNA UCA1 inactivated the PTEN/AKT signaling pathway. Finally, we observed that HIF-1α induced cell growth through the UCA1/PTEN/AKT signaling pathway. To conclude, our integrated approach demonstrates that UCA1 confers a tumor promoter function by promoting cell proliferation and silencing of the PTEN/AKT signaling pathway in osteosarcoma. Thus, UCA1 can serve as a promising therapeutic target for osteosarcoma patients.

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.

The GAS5/miR-222 Axis Regulates Proliferation of Gastric Cancer Cells Through the PTEN/Akt/mTOR Pathway

BACKGROUND

Several lines of evidence have indicated that growth arrest-specific transcript 5 (GAS5) functions as a tumor suppressor and is aberrantly expressed in multiple cancers. GAS5 was found to be downregulated in gastric cancer (GC) tissues, and ectopic expression of GAS5 inhibited GC cell proliferation.

AIMS

The present study aimed to explore the underlying mechanisms of GAS5 involved in GC cell proliferation.

METHODS

GAS5 and miR-222 expressions in GC cell lines were estimated by quantitative real-time polymerase chain reaction. The effects of GAS5 and miR-222 on GC cell proliferation were assessed by MTT assay and 5-bromo-2-deoxyuridine (BrdU) incorporation assays. The interaction between GAS5 and miR-222 was confirmed by luciferase reporter assay and RNA immunoprecipitation assay. The protein levels of the phosphatase and tensin homolog (PTEN), phosphorylated protein kinase B (Akt) (p-Akt), Akt, phosphorylated mammalian target of rapamycin (mTOR) (p-mTOR), and mTOR were determined by western blot.

RESULTS

GAS5 was downregulated and miR-222 was upregulated in GC cells. GAS5 directly targeted and suppressed miR-222 expression. GAS5 overexpression and miR-222 inhibition suppressed cell proliferation, increased PTEN protein level and decreased p-Akt and p-mTOR protein levels in GC cells while GAS5 knockdown and miR-222 overexpression exhibited the opposite effects. Moreover, mechanistic analyses revealed that GAS5 regulated GC cell proliferation through the PTEN/Akt/mTOR pathway by negatively regulating miR-222.

CONCLUSIONS

GAS5/miR-222 axis regulated proliferation of GC cells through the PTEN/Akt/mTOR pathway, which facilitated the development of lncRNA-directed therapy against this deadly disease.

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 RNA AFAP1-AS1 is a novel biomarker in various cancers: a systematic review and meta-analysis based on the literature and GEO datasets

Background

Growing evidence indicates that AFAP1-AS1 plays an important role in various cancers, suggesting that it might be a potential cancer biomarker.

Materials and Methods

A meta-analysis was performed using microarray data obtained via the Affymetrix Human Genome U133 Plus 2.0 platform (found in the GEO database) and data obtained through a systematic search of PubMed and Web of Science. The pooled odds ratio (OR) and hazard ratio (HR) with 95% CI (confidence interval) were used to judge the value of biomarkers.

Results

A total of 30 studies were included in this meta-analysis, comprising a total of 3573 patients. AFAP1-AS1 was significantly linked with overall survival (OS) (HR = 1.58; 95% CI: 1.12–2.23) and recurrence-free survival (RFS) (HR = 2.32, 95% CI: 1.68–3.19). We found that AFAP1-AS1 was a risk factor in the prognoses of lung cancer (pooled HR: 1.54; 95% CI: 1.01–2.34), digestive system cancer (pooled HR: 1.87; 95% CI: 1.45–2.41) and nasopharyngeal carcinoma (HR: 11.82; 95% CI: 5.09–27.46). AFAP1-AS1 was also a risk factor for RFS in breast cancer (pooled HR = 2.90; 95% CI: 1.69–4.98), as well as TNM stage in both esophageal cancer (pooled OR = 1.90; 95% CI: 1.01–3.57) and colorectal cancer (OR = 6.72; 95% CI: 1.92–23.58). AFAP1-AS1 was significantly associated with lymph node metastasis in clear cell carcinoma (OR = 5.04; 95% CI: 2.36–10.78) and distant metastasis in pancreatic cancer (OR = 11.64; 95% CI: 2.13–63.78).

Conclusions

AFAP1-AS1 can serve as a novel molecular marker predicting tumor progression, patient prognosis and lymph node metastasis in different types of cancers.

Silencing of lncRNA AFAP1-AS1 suppressed lung cancer development by regulatory mechanism in cis and trans

Although the long noncoding RNA AFAP1-AS1 has been shown to be involved in various types of cancer, its involvement in lung cancer remains poorly understood. In the current study, we found that AFAP1-AS1 was substantially over expressed in lung cancer tissues and cell lines. In addition, AFAP1-AS1 expression level was proven to be associated with the malignant features of lung cancer. Knockdown of AFAP1-AS1 significantly suppressed cell proliferation by increasing cell apoptosis and G0/G1 phase retardation of cell cycle in lung cancer cells. Furthermore, AFAP1-AS1 knockdown could suppress tumor growth of lung cancer in BALB/c nude mice. We also identified that AFAP1-AS1 silencing could influence the expression of AFAP1 and KRT1 on mRNA and protein level by cis and trans regulatory mechanism. Moreover, the oncogenic activities of AFAP1-AS1 on cell proliferation are partially mediated by KRT1. In summary, these findings demonstrate that AFAP1-AS1 plays an essential role in promoting lung cancer development in vitro and vivo. It indicated that AFAP1-AS1 is a promising prognostic predictor for patients with lung cancer.

Expression and function of transforming growth factor‑β‑activated protein kinase 1 in gastric cancer

The present study aimed to investigate the expression and role of transforming growth factor (TGF) ‑β‑activated protein kinase 1 (TAK1) in human gastric cancer. Immunohistochemistry was performed to investigate the expression of TAK1 in surgical specimens of human gastric cancer tissue and adjacent normal tissue. The association between TAK1 and clinicopathologic factors was analyzed and the association between TAK1 expression and the overall survival rates was evaluated using Kaplan‑Meier curves. In addition, the effect of the TAK1 selective inhibitor 5Z‑7‑oxozeaenol (OZ) on the biological characteristics of MGC803 human gastric cancer cells in vitro were investigated. The role of TAK1 in gastric cancer cell proliferation, apoptosis and invasion were determined by cell proliferation assays, flow cytometry analysis and transwell invasion assays, respectively. The findings of the present study demonstrated that the positive expression rate of TAK1 in gastric cancer and adjacent normal tissues was 70.5 and 25.9%, respectively. Furthermore, TAK1 expression was significantly associated with advanced N stage and pathological stage (P<0.05). Survival analysis of 139 patients with gastric cancer indicated a lower overall survival rate of patients in the TAK1‑positive group compared with the TAK1‑negative group (P<0.05). In addition, treatment with the TAK1 selective inhibitor OZ reduced the proliferation and invasion abilities of MGC803 cells and significantly reduced the expression levels of phosphorylated‑TAK1 (Thr187), nuclear p65, cyclin D1, Bcl‑2 apoptosis regulator and matrix metallopeptidase (MMP)9 (P<0.05). OZ treatment significantly increased the expression levels of cytosolic cytochrome c and cleaved caspase 3 and the apoptosis rate in MGC803 cells (P<0.05). In conclusion, these findings suggest that increased TAK1 expression may be involved in the progression of gastric cancer; therefore, TAK1 may be used as a future therapeutic target for gastric cancer treatment.

Genomic Insight into the Role of lncRNA in Cancer Susceptibility

With the development of advanced genomic methods, a large amount of long non-coding RNAs (lncRNAs) has been found to be important for cancer initiation and progression. Given that most of the genome-wide association study (GWAS)-identified cancer risk SNPs are located in the noncoding region, the expression and function of lncRNAs are more likely to be affected by the SNPs. The SNPs may affect the expression of lncRNAs directly through disrupting the binding of transcription factors or indirectly by affecting the expression of regulatory factors. Moreover, SNPs may disrupt the interaction between lncRNAs and other RNAs or proteins. Unveiling the relationship of lncRNA, protein-coding genes, transcription factors and miRNAs from the angle of genomics will improve the accuracy of disease prediction and help find new therapeutic targets.