Long noncoding RNA aberrant expression profiles after cytoreductive surgery and hyperthermic intraperitoneal chemotherapy of AGC ascertained by microarray analysis. Tumour Biol. 2015;36:5021-5029. [PMID: 25652469 DOI: 10.1007/s13277-015-3153-4]

Long non-coding RNA GATA6-AS1 is mediated by N6-methyladenosine methylation and inhibits the proliferation and metastasis of gastric cancer

BACKGROUND

Through experimental research on the biological function of GATA6-AS1, it was confirmed that GATA6-AS1 can inhibit the proliferation, invasion, and migration of gastric cancer cells, suggesting that GATA6-AS1 plays a role as an anti-oncogene in the occurrence and development of gastric cancer. Further experiments confirmed that the overexpression of fat mass and obesity-associated protein (FTO) inhibited the expression of GATA6-AS1, thereby promoting the occurrence and development of gastric cancer.

AIM

To investigate the effects of GATA6-AS1 on the proliferation, invasion and migration of gastric cancer cells and its mechanism of action.

METHODS

We used bioinformatics methods to analyze the Cancer Genome Atlas (https://portal.gdc.cancer.gov/. The Cancer Genome Atlas) and download expression data for GATA6-AS1 in gastric cancer tissue and normal tissue. We also constructed a GATA6-AS1 lentivirus overexpression vector which was transfected into gastric cancer cells to investigate its effects on proliferation, migration and invasion, and thereby clarify the expression of GATA6-AS1 in gastric cancer and its biological role in the genesis and development of gastric cancer. Next, we used a database (http://starbase.sysu.edu.cn/starbase2/) to analysis GATA6-AS1 whether by m6A methylation modify regulation and predict the methyltransferases that may methylate GATA6-AS1. Furthermore, RNA immunoprecipitation experiments confirmed that GATA6-AS1 was able to bind to the m6A methylation modification enzyme. These data allowed us to clarify the ability of m6A methylase to influence the action of GATA6-AS1 and its role in the occurrence and development of gastric cancer.

RESULTS

Low expression levels of GATA6-AS1 were detected in gastric cancer. We also determined the effects of GATA6-AS1 overexpression on the biological function of gastric cancer cells. GATA6-AS1 had strong binding ability with the m6A demethylase FTO, which was expressed at high levels in gastric cancer and negatively correlated with the expression of GATA6-AS1. Following transfection with siRNA to knock down the expression of FTO, the expression levels of GATA6-AS1 were up-regulated. Finally, the proliferation, migration and invasion of gastric cancer cells were all inhibited following the knockdown of FTO expression.

CONCLUSION

During the occurrence and development of gastric cancer, the overexpression of FTO may inhibit the expression of GATA6-AS1, thus promoting the proliferation and metastasis of gastric cancer.

Noncoding RNAs and hyperthermic intraperitoneal chemotherapy in advanced gastric cancer

Gastric cancer (GC) is one of the most common malignant tumors globally. About 20-30% of patients with gastric cancer show peritoneal implantation metastasis at the first diagnosis. Peritoneal metastasis is responsible for 70% of deaths of patients with advanced gastric cancer. Although there are many ways to treat advanced gastric cancer, the prognosis of patients with recurrence is unsatisfactory. An auxiliary treatment with hyperthermic intraperitoneal chemotherapy (HIPEC), is an internationally recognized recommended treatment for advanced gastric cancer. A series of clinical trials have shown that HIPEC significantly improves the overall survival of patients with cancer. Compared with the cytoreductive surgery (CRS) alone, HIPEC combined with CRS markedly reduced the rate of peritoneal metastasis in patients with ovarian cancer and colorectal cancer. It has been demonstrated that HIPEC alters transcription of many genes by affecting non-coding RNAs, which may contribute to the suppressive effect of HIPEC on the synthesis of nucleic acids and proteins in cancer cells. This paper reviews the recent advances in understanding the role of non-coding RNAs in tumor invasion and metastasis of advanced gastric cancer. We also consider changes in noncoding RNA levels and other molecules in advanced gastric cancer cases treated with HIPEC. We hope that our review will provide a reference for future research on molecular epidemiology and etiology of advanced gastric cancer and promote precise treatment of this malignancy using HIPEC.

Differential expression profile of long noncoding RNAs in chronic HBV infection: New insights into pathogenesis

Increasing studies have revealed that long noncoding RNAs (lncRNAs) might play vital roles in the development and progression of various diseases including viral infectious diseases. However, the expression and biological functions of lncRNAs in chronic hepatitis B virus (HBV) infection remain largely unknown. Therefore, lncRNA microarray was performed to analyze the lncRNAs' and messenger RNAs' (mRNAs) expression profiles in liver tissues from patients with chronic HBV infection. Subsequently, a comprehensive bioinformatics analysis was conducted to investigate the potential functions of the differentially expressed genes. As a result, a total of 203 differentially expressed lncRNAs and 180 mRNAs were identified in chronic HBV infection. The expressions of five differentially expressed lncRNAs were further validated using quantitative real-time polymerase chain reaction. Gene ontology, pathway analysis, and gene set enrichment analysis revealed that differentially expressed lncRNAs might be mainly be involved in cytokine-cytokine receptor interaction and varied biotransformation processes, including fatty acid metabolism, amino acid metabolism, carbon metabolism, and drug metabolism. Additionally, coexpression networks between differentially expressed lncRNAs and mRNAs were constructed to reveal the hub regulator and analyze the functional pathways. This study provided an overview of lncRNA and mRNA expression in liver tissues from patients with chronic HBV infection. These differentially expressed lncRNAs might play crucial roles in the pathogenesis and progression of chronic HBV infection, which deserve further investigation.

Overexpressed lncRNA GATA6-AS1 Inhibits LNM and EMT via FZD4 through the Wnt/β-Catenin Signaling Pathway in GC

Gastric cancer (GC) is one of the leading causes of cancer-related deaths worldwide. Accumulating evidence reveals the significance of long non-coding RNAs (lncRNAs) in various cancers. The current study aimed to evaluate the role of GATA6 antisense RNA 1 (GATA6-AS1) in the epithelial-mesenchymal transition (EMT) and lymph node metastasis (LNM) in GC. GC-related microarray datasets were initially retrieved from the GEO with differentially expressed lncRNAs screened, followed by evaluation of the regulatory relationship between Frizzled 4 (FZD4) and GATA6-AS1. The detailed regulatory mechanism by which GATA6-AS1 influences the Wnt/β-catenin signaling pathway and GC cell biological behaviors was investigated by treating SGC7901 cells with overexpressed GATA6-AS1, specific antisense oligonucleotide against GATA6-AS1, and lithium chloride (LiCl; activator of the Wnt/β-catenin signaling pathway). Finally, xenograft nude mice were used to assay tumor growth and LNM in vivo. GATA6-AS1 was poorly expressed, but FZD4 was highly expressed in GC tissues and cells. Elevated GATA6-AS1 reduced FZD4 expression by recruiting enhancer of zeste homolog 2 (EZH2) and trimethylation at lysine 27 of histone H3 (H3K27me3) to the FZD4 promoter region via the inactivated Wnt/β-catenin signaling pathway, whereby cell invasion, migration, and proliferation, tumor growth, and LNM in nude mice were reduced. Taken together, overexpressed GATA6-AS1 downregulated the expression of FZD4 to inactivate the Wnt/β-catenin signaling pathway, which ultimately inhibited GC progression.

LINC01133 as ceRNA inhibits gastric cancer progression by sponging miR-106a-3p to regulate APC expression and the Wnt/β-catenin pathway

Background

Gastric cancer (GC) is a common malignancy and frequent cause of cancer-related death. Long non-coding RNAs (lncRNAs) have emerged as important regulators and tissue-specific biomarkers of multiple cancers, including GC. Recent evidence has indicated that the novel lncRNA LINC01133 plays an important role in cancer progression and metastasis. However, its function and molecular mechanism in GC remain largely unknown.

Methods

LINC01133 expression was detected in 200 GC and matched non-cancerous tissues by quantitative reverse transcription PCR. Gain- and loss-of-function experiments were conducted to investigate the biological functions of LINC01133 both in vitro and in vivo. Insights into the underlying mechanisms of competitive endogenous RNAs (ceRNAs) were determined by bioinformatics analysis, dual-luciferase reporter assays, quantitative PCR arrays, TOPFlash/FOPFlash reporter assay, luciferase assay, and rescue experiments.

Results

LINC01133 was downregulated in GC tissues and cell lines, and its low expression positively correlated with GC progression and metastasis. Functionally, LINC01133 depletion promoted cell proliferation, migration, and the epithelial–mesenchymal transition (EMT) in GC cells, whereas LINC01133 overexpression resulted in the opposite effects both in vitro and in vivo. Bioinformatics analysis and luciferase assays revealed that miR-106a-3p was a direct target of LINC01133, which functioned as a ceRNA in regulating GC metastasis. Mechanistic analysis demonstrated that miR-106a-3p specifically targeted the adenomatous polyposis coli (APC) gene, and LINC01133/miR-106a-3p suppressed the EMT and metastasis by inactivating the Wnt/β-catenin pathway in an APC-dependent manner.

Conclusions

Our findings suggest that reduced expression of LINC01133 is associated with aggressive tumor phenotypes and poor patient outcomes in GC. LINC01133 inhibits GC progression and metastasis by acting as a ceRNA for miR-106a-3p to regulate APC expression and the Wnt/β-catenin pathway, suggesting that LINC01133 may serve as a potential prognostic biomarker and anti-metastatic therapeutic target for GC.

Electronic supplementary material

The online version of this article (10.1186/s12943-018-0874-1) contains supplementary material, which is available to authorized users.

Liquid biopsy provides new insights into gastric cancer

Liquid biopsies have great promise for precision medicine as they provide information about primary and metastatic tumors via a minimally invasive method. In gastric cancer patients, a large number of blood-based biomarkers have been reported for their potential role in clinical practice for screening, early diagnosis, prognostic evaluation, recurrence monitoring and therapeutic efficiency follow-up. This current review focuses on blood liquid biopsies' role and their clinical implications in gastric cancer patients, with an emphasis on circulating tumor cells (CTCs), circulating tumor DNA (ctDNA) and circulating non-coding RNAs (ncRNAs). We also provide a brief discussion of the potential and limitations of liquid biopsies use and their future use in the routine clinical care of gastric cancer.

Emerging blood-based biomarkers for detection of gastric cancer

Early detection and efficient monitoring of tumor dynamics are prerequisites for reducing disease burden and mortality, and for improving the management of patients with gastric cancer (GC). Blood-based biomarker assays for the detection of early-stage GC could be of great relevance both for population-wide or risk group-based screening programs, while circulating biomarkers that reflect the genetic make-up and dynamics of the tumor would allow monitoring of treatment efficacy, predict recurrences and assess the genetic heterogeneity of the tumor. Recent research to identify blood-based biomarkers of GC has resulted in the identification of a wide variety of cancer-associated molecules, including various proteins, autoantibodies against tumor associated antigens, cell-free DNA fragments, mRNAs and various non-coding RNAs, circulating tumor cells and cancer-derived extracellular vesicles. Each type of these biomarkers provides different information on the disease status, has different advantages and disadvantages, and distinct clinical usefulness. In the current review, we summarize the recent developments in blood-based GC biomarker discovery, discuss the origin of various types of biomarkers and their clinical usefulness and the technological challenges in the development of biomarker assays for clinical use.