Downregulation of Kruppel-like factor 2 is associated with poor prognosis for nonsmall-cell lung cancer

Comprehensive analysis of KLF2 as a prognostic biomarker associated with fibrosis and immune infiltration in advanced hepatocellular carcinoma

PURPOSE

Most Hepatocellular carcinoma (HCC) patients are in advanced or metastatic stage at the time of diagnosis. Prognosis for advanced HCC patients is dismal. This study was based on our previous microarray results, and aimed to explore the promising diagnostic and prognostic markers for advanced HCC by focusing on the important function of KLF2.

METHODS

The Cancer Genome Atlas (TCGA), Cancer Genome Consortium database (ICGC), and the Gene Expression Comprehensive Database (GEO) provided the raw data of this study research. The cBioPortal platform, CeDR Atlas platform, and the Human Protein Atlas (HPA) website were applied to analyze the mutational landscape and single-cell sequencing data of KLF2. Basing on the results of single-cell sequencing analyses, we further explored the molecular mechanism of KLF2 regulation in the fibrosis and immune infiltration of HCC.

RESULTS

Decreased KLF2 expression was discovered to be mainly regulated by hypermethylation, and indicated a poor prognosis of HCC. Single-cell level expression analyses revealed KLF2 was highly expressed in immune cells and fibroblasts. The function enrichment analysis of KLF2 targets indicated the crucial association between KLF2 and tumor matrix. 33-genes related with cancer associated fibroblasts (CAFs) were collected to identify the significant association of KLF2 with fibrosis. And SPP1 was validated as a promising prognostic and diagnostic marker for advanced HCC patients. CXCR6 CD8+ T cells were noted as a predominant proportion in the immune microenvironment, and T cell receptor CD3D was discovered to be a potential therapeutic biomarker for HCC immunotherapy.

CONCLUSION

This study identified that KLF2 is an important factor promoting HCC progression by affecting the fibrosis and immune infiltration, highlighting its great potential as a novel prognostic biomarker for advanced HCC.

Krüppel-Like Factor 2 Is a Gastric Cancer Suppressor and Prognostic Biomarker

Gastric cancer (GC) is a common digestive tract tumor. Due to its complex pathogenesis, current diagnostic and therapeutic effects remain unsatisfactory. Studies have shown that KLF2, as a tumor suppressor, is downregulated in many human cancers, but its relationship and role with GC remain unclear. In the present study, KLF2 mRNA levels were significantly lower in GC compared to adjacent normal tissues, as analyzed by bioinformatics and RT-qPCR, and correlated with gene mutations. Tissue microarrays combined with immunohistochemical techniques showed downregulation of KLF2 protein expression in GC tissue, which was negatively correlated with patient age, T stage, and overall survival. Further functional experiments showed that knockdown of KLF2 significantly promoted the growth, proliferation, migration, and invasion of HGC-27 and AGS GC cells. In conclusion, low KLF2 expression in GC is associated with poor patient prognosis and contributes to the malignant biological behavior of GC cells. Therefore, KLF2 may serve as a prognostic biomarker and therapeutic target in GC.

Bioinformatics Analysis of mRNAs and miRNAs for Identifying Potential Biomarkers in Lung Adenosquamous Carcinoma

Background

Lung adenosquamous carcinoma (LASC) is a special type of lung cancer. LASC is a malignant tumor with strong aggressiveness and a poor prognosis. Previous studies have revealed that microRNAs (miRNAs) are widely involved in the development of tumors by targeting mRNA. This study is aimed at identifying the key mRNAs and miRNAs of LASC and constructing miRNA-mRNA networks for deeply comprehending the latent molecular mechanisms.

Methods

mRNA dataset (GSE51852) and miRNA dataset (GSE51853) were extracted and downloaded from the Gene Expression Omnibus (GEO) database. Differentially expressed genes (DEGs) and differentially expressed miRNAs (DEMs) were picked out by the GEO2R web tool. Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) functional enrichment analyses were conducted in the DAVID database. The protein-protein interaction (PPI) network was performed and analyzed by using the STRING database and Cytoscape software, respectively. TransmiR v2.0 was applied to predict potential transcription factors of miRNAs. The target genes of DEMs were predicted in the miRWalk database.

Results

In comparison to normal tissues, a total of 1458 DEGs (511 upregulated and 947 downregulated) and 13 DEMs (5 upregulated and 8 downregulated) were screened out in LASC tissues. The PPI network of the DEGs displayed five key modules and seventeen hub genes. Six target genes of the DEMs were predicted, and five essential miRNA-mRNA regulatory pairs were established. Ensuingly, CENPF, one of the target genes, was also the hub genes of GSE51852, which was obtained from MCODE and cytoHubba and regulated by hsa-miR-205.

Conclusions

We constructed the miRNA-mRNA regulatory pairs, which are helpful to study the potential regulatory mechanisms and find out promising diagnosis biomarkers and therapeutic targets for LASC.

Upregulated long noncoding RNAs LINC02163 and FEZF1-AS1 exert oncogenic roles in colorectal cancer

A growing number of evidence has revealed that aberrantly expressed long noncoding RNAs (lncRNAs) are involved in the development of a variety of malignancies, including colorectal cancer (CRC). However, the clinical relevance of most lncRNAs and their potential biological functions in CRC remains poorly understood. The aim of this study was to identify the key lncRNAs related to patient prognosis as well as their biological function and underlying mechanism in CRC. Therefore, five independent datasets containing CRC and normal tissue RNA sequencing, microarray data and the corresponding clinical data from The Cancer Genome Atlas and Gene Expression Omnibus were screened. Hundreds of significantly differentially expressed lncRNAs in CRC were determined, and Kaplan-Meier analyses revealed that some of these lncRNAs were related to the overall survival and progression-free survival of patients with CRC, such as RP11-108K3.2, FOXD3-AS1, H19 and AP001469.9. Among these dysregulated lncRNAs, LINC02163 and FEZF1-AS1 were significantly upregulated in CRC tissues, suggesting that they may have oncogenic roles in CRC. Furthermore, loss of function assays revealed that downregulation of LINC02163 and FEZF1-AS1 impaired CRC cell proliferation. In addition, RNA Immunoprecipitation and Chromatin Immunoprecipitation assays determined that FEZF1-AS1 regulates CRC cell growth via interacting with LSD1 and repressing KLF2 expression. Collectively, hundreds of dysregulated lncRNAs and their associated biological roles identified in this study may provide potentially useful biomarkers and therapeutic targets for CRC.

DT-13 induced apoptosis and promoted differentiation of acute myeloid leukemia cells by activating AMPK-KLF2 pathway

Acute myeloid leukemia (AML) is a malignant disease originating from hematopoietic stem cells (HSC). Chemotherapy and/or HSC transplantation is unsatisfactory due to serious side effects, multidrug resistance, and high relapse rate. Thus, alternative strategies are urgently needed to develop more effective therapies. Liriope muscari baily saponins C (DT-13) is a novel compound isolated from Liriope muscari (Decne.) Baily, and exhibited a potent cytotoxicity against several solid tumors. However, the anti-AML activity of DT-13 and the potential mechanisms are still unknown. This study is the first to demonstrate that DT-13 had preferential cytotoxicity against AML cells, and remarkably inhibited proliferation and colony forming ability. Moreover, DT-13 induced the death receptor pathway-dependent apoptosis of HL-60 and Kasumi-1 cells by up-regulating Fas, FasL, DR5 and TRAIL as well as promoted the cleavage of caspase 8, caspase 3 and PARP. Meanwhile, DT-13 induced the differentiation with morphological change related to myeloid differentiation, elevated NBT and α-NAE positive cell rates, differentiation markers CD11b and CD14 as well as level of transcription factors C/EBPα and C/EBPβ. RNA-sequencing analysis revealed that KLF2 may be one of the potential targets regulated by DT-13. Further studies indicated that KLF2 played a critical role in DT-13-induced apoptosis and differentiation. Moreover, activation of AMPK-FOXO was proved to be the upstream of KLF2 pathway that contributed to the induction of apoptosis and differentiation by DT-13. Additionally, restoration of KLF2 by DT-13 was highly correlated with the AMPK-related histone acetylation mechanisms. Finally, DT-13 exhibited an obvious anti-AML effect in NOD/SCID mice with the engraftment of HL-60 cells. Our study suggests that DT-13 may serve as a novel agent for AML by AMPL-KLF2-mediated apoptosis and differentiation.

LINP1 promotes the progression of cervical cancer by scaffolding EZH2, LSD1, and DNMT1 to inhibit the expression of KLF2 and PRSS8

There is a growing body of evidence indicating that long non-coding RNAs (lncRNAs) are associated with a variety of cancers. LncRNA LINP1 has been shown to be a key factor in tumor malignancy. However, the role of LINP1 in cervical cancer (CC) it is unclear. In our research, we found that the levels of LINP1 were significantly elevated in CC tissues by comparison with adjacent normal tissue. Further, the expression level of LINP1 was upregulated in CC cells compared with healthy human cervical epithelial cell lines (HUCEC). Surprisingly, we found that downregulation of LINP1 significantly reduced the proliferation of CC cells and promoted apoptosis. Additionally, downregulation of LINP1 significantly decreased CC tumor growth in vivo. Further, we observed that LINP1 recruits EZH2, LSD1, and DNMT1, thereby reducing the expression of KLF2 and PRSS8. The results from our qRT-PCR analyses showed that silencing LINP1 uprgulated the expression of KLF2 and PRSS8 in CC cells. The results from our loss-of-function assays showed that upregulation of KLF2 and PRSS8 inhibits cell proliferation and boosts cell apoptosis in CC. We also found that inhibition of KLF2 and PRSS8 reversed the inhibitory effect on cell proliferation associated with silencing LINP1. In short, LINP1 facilitates the progression of CC by suppressing KLF2 and PRSS8, and thus could provide a promising target for CC therapy.

Kruppel-like factor 2 disturb non-small cell lung cancer energy metabolism by inhibited glutamine consumption

OBJECTIVES

Metabolic reprogramming is well accepted as a hallmark of cancer. This study aimed to explore the role of Kruppel-like factor 2 (KLF2) in aerobic glycolysis and glutamine consumption of energy metabolism in non-small cell lung cancer (NSCLC) cells.

METHODS

Two different NSCLC cells, A549 and NCI-H1299, were used to investigate the role of KLF2 in glycolysis and glutamine consumption by tracer technique and KLF2 transfection.

KEY FINDINGS

The results showed that overexpression KLF could inhibit the energy metabolism and proliferation of NSCLC cells, but had no significant effect on glycolysis reaction and only affected the glutamine consumption of NSCLC cells. In NSCLC cells exposed to glutamine deprivation, the effect of overexpression of KLF2 on cell proliferation and energy metabolism disappeared. It was found that KLF2 could inhibit the expression of glutaminase (GLS) by metabolite tracing technique and so on. However, when GLS inhibitors were given to overexpressing KLF2 NSCLC cells, the intervention effect of KLF2 disappeared.

CONCLUSIONS

Kruppel-like factor 2 could decrease the level of glutamine, participate in the consumption of glutamine by cancer cells, and then inhibit the energy metabolism of cancer cells.

Epstein-Barr Virus miR-BART17-5p Promotes Migration and Anchorage-Independent Growth by Targeting Kruppel-Like Factor 2 in Gastric Cancer

Epstein-Barr virus (EBV) infects more than 90% of the global population and is associated with a variety of tumors including nasopharyngeal carcinoma, Hodgkin lymphoma, natural killer/T lymphoma, and gastric carcinoma. In EBV-associated gastric cancer (EBVaGC), highly expressed EBV BamHI A rightward transcripts (BART) miRNAs may contribute to tumorigenesis with limited viral antigens. Despite previous studies on the targets of BART miRNAs, the functions of all 44 BART miRNAs have not been fully clarified. Here, we used RNA sequencing data from the Cancer Genome Atlas to find genes with decreased expression in EBVaGC. Furthermore, we used AGS cells infected with EBV to determine whether expression was reduced by BART miRNA. We showed that the expression of Kruppel-like factor 2 (KLF2) is lower in AGS-EBV cells than in the AGS control. Using bioinformatics analysis, four BART miRNAs were selected to check whether they suppress KLF2 expression. We found that only miR-BART17-5p directly down-regulated KLF2 and promoted gastric carcinoma cell migration and anchorage-independent growth. Our data suggest that KLF2 functions as a tumor suppressor in EBVaGC and that miR-BART17-5p may be a valuable target for effective EBVaGC treatment.

KLF2 Inhibits the Migration and Invasion of Prostate Cancer Cells by Downregulating MMP2

KLF2, a member of the Kruppel-like factor (KLF) family, is thought to be a tumor suppressor in many kinds of malignant tumors. Its functions in prostate cancer (PCa) are unknown. This study aimed to explore the role of KLF2 in the migration and invasion of PCa cells. The expression of KLF2 was measured by immunohistochemistry in PCa tissues and in paired non-tumor tissues. KLF2 and MMP2 expression in cells was measured by Western blot and RT-qPCR. Adenoviruses and siRNAs were used in cell function tests to investigate the role of KLF2 in regulating MMP2. Interactions between KLF2 and MMP2 were analyzed by a luciferase activity assay. The present study, for the first time, identified that KLF2 was downregulated both in PCa clinical tissue samples and in cancer cell lines. The overexpression of KLF2 inhibited the migration and invasion of PCa cells via the suppression of MMP2.This study demonstrates that KLF2 might act as a tumor suppressor gene in PCa and that the pharmaceutical upregulation of KLF2 may be a potential approach for treatment.

Gene expression analysis of Atlantic salmon gills reveals mucin 5 and interleukin 4/13 as key molecules during amoebic gill disease

Amoebic gill disease (AGD) is one of the main diseases affecting Atlantic salmon (Salmo salar L.) mariculture. Hallmarks of AGD are hyperplasia of the lamellar epithelium and increased production of gill mucus. This study investigated the expression of genes involved in mucus secretion, cell cycle regulation, immunity and oxidative stress in gills using a targeted 21-gene PCR array. Gill samples were obtained from experimental and natural Neoparamoeba perurans infections, and sampling points included progressive infection stages and post-freshwater treatment. Up-regulation of genes related to mucin secretion and cell proliferation, and down-regulation of pro-inflammatory and pro-apoptotic genes were associated with AGD severity, while partial restoration of the gill homeostasis was detected post-treatment. Mucins and Th2 cytokines accoun ted for most of the variability observed between groups highlighting their key role in AGD. Two mucins (muc5, muc18) showed differential regulation upon disease. Substantial up-regulation of the secreted muc5 was detected in clinical AGD, and the membrane bound muc18 showed an opposite pattern. Th2 cytokines, il4/13a and il4/13b2, were significantly up-regulated from 2 days post-infection onwards, and changes were lesion-specific. Despite the differences between experimental and natural infections, both yielded comparable results that underline the importance of the studied genes in the respiratory organs of fish, and during AGD progression.

KLF15 suppresses cell growth and predicts prognosis in lung adenocarcinoma

Krüppel-like factors (KLFs) are transcription factors containing three different C2H2-type zinc finger domains in their carboxy-terminal regions which have been identified to play important roles in a variety of cancers. However, little is known about KLF15 in lung adenocarcinoma (LAUD). Our study demonstrated that the expression levels of KLF15 were observably down-regulated in LAUD tissues compared to paired adjacent normal tissues. LUAD patients with low expression levels of KLF15 have worse prognosis than those with high expression levels of KLF15. KLF15 could suppress cell growth, which was partly via up-regulating CDKN1 A/p21 and CDKN2A/p15. Our findings suggested that KLF15 showed a significant role in LAUD progression and may shed light on a promising novel therapeutic target for blocking progression of LAUD.

CDK8 regulates the angiogenesis of pancreatic cancer cells in part via the CDK8-β-catenin-KLF2 signal axis

BACKGROUND

CDK8 is associated with the transcriptional Mediator complex and has been shown to regulate several transcription factors implicated in cancer. As a pancreatic cancer oncogene, the role of CDK8 in cancer angiogenesis remains unclear. Here, we investigated the contribution of CDK8 in pancreatic cancer angiogenesis and examined the underlying molecular mechanisms.

METHODS

CDK8 expression was evaluated via immunohistochemistry, western blotting, and qRT-PCR in relation to the clinicopathological characteristics of pancreatic cancer patients. The effects of silencing or overexpressing CDK8 on cancer angiogenesis were assessed in vitro by western blotting assays in pancreatic cancer cell lines and in vivo with nude mice xenograft models.

RESULTS

Compared with adjacent normal tissues, pancreatic cancer tissues showed upregulation of CDK8 expression, which was inversely correlated with T grade, liver metastasis, size, lymph node metastasis and poor survival. CDK8 overexpression promoted angiogenesis in pancreatic cancer via activation of the CDK8-β-catenin-KLF2 signaling axis, as demonstrated by the upregulation and downregulation of signals representing the rate-limiting steps in angiogenesis. Silencing CDK8 inhibited angiogenesis in pancreatic cancer in vitro. Additionally, these results were confirmed in nude mice xenograft models in vivo.

CONCLUSIONS

CDK8 promotes angiogenesis in pancreatic cancer via activation of the CDK8-β-catenin-KLF2 signaling axis, thus providing valid targets for the treatment of pancreatic cancer.

SP1-induced upregulation of lncRNA SPRY4-IT1 exerts oncogenic properties by scaffolding EZH2/LSD1/DNMT1 and sponging miR-101-3p in cholangiocarcinoma

Background

Accumulating evidence has indicated that long non-coding RNAs (lncRNAs) behave as a novel class of transcription products during multiple cancer processes. However, the mechanisms responsible for their alteration in cholangiocarcinoma (CCA) are not fully understood.

Methods

The expression of SPRY4-IT1 in CCA tissues and cell lines was determined by RT-qPCR, and the association between SPRY4-IT1 transcription and clinicopathologic features was analyzed. Luciferase reporter and chromatin immunoprecipitation (ChIP) assays were performed to explore whether SP1 could bind to the promoter region of SPRY4-IT1 and activate its transcription. The biological function of SPRY4-IT1 in CCA cells was evaluated both in vitro and in vivo. ChIP, RNA binding protein immunoprecipitation (RIP) and luciferase reporter assays were performed to determine the molecular mechanism of SPRY4-IT1 in cell proliferation, apoptosis and invasion.

Results

SPRY4-IT1 was abnormally upregulated in CCA tissues and cells, and this upregulation was correlated with tumor stage and tumor node metastasis (TNM) stage in CCA patients. SPRY4-IT1 overexpression was also an unfavorable prognostic factor for patients with CCA. Additionally, SP1 could bind directly to the SPRY4-IT1 promoter region and activate its transcription. Furthermore, SPRY4-IT1 silencing caused tumor suppressive effects via reducing cell proliferation, migration and invasion; inducing cell apoptosis and reversing the epithelial-to-mesenchymal transition (EMT) process in CCA cells. Mechanistically, enhancer of zeste homolog 2 (EZH2) along with the lysine specific demethylase 1 (LSD1) or DNA methyltransferase 1 (DNMT1) were recruited by SPRY4-IT1, which functioned as a scaffold. Importantly, SPRY4-IT1 positively regulated the expression of EZH2 through sponging miR-101-3p.

Conclusions

Our data illustrate how SPRY4-IT1 plays an oncogenic role in CCA and may offer a potential therapeutic target for treating CCA.

Electronic supplementary material

The online version of this article (10.1186/s13046-018-0747-x) contains supplementary material, which is available to authorized users.

Krüppel-like factor 2 suppresses human gastric tumorigenesis through inhibiting PTEN/AKT signaling

Krüppel-like factors (KLFs) are a large family of DNA-binding transcriptional regulators that affect basic cellular processes such as growth, survival, migration and differentiation and serve a complicated function in cancers. KLF2, one member of the KLF family, is dysregulated in many tumors. However, the specific role of KLF2 in human gastric tumorigenesis is unknown. Here we show that the expression of KLF2 protein was lower in gastric tumors when compared with adjacent normal tissue. Moreover, downregulated KLF2 expression in primary gastric tumor was closely correlated with patients’ survival. Various cell experiments showed that ectopic KLF2 expression suppressed the proliferation, migration and invasion of gastric cancer cells. Moreover, KLF2 overexpression remarkably enhanced cell apoptosis and induced cell cycle arrest. Impaired expression of KLF2 markedly promoted cell growth in vitro and significantly expanded tumor size in vivo. Mechanically, the mRNA and protein level of PTEN was reduced in KLF2 deficient cells and xenograft tumors, suggesting that PTEN/AKT signaling was involved in the gastric tumor inhibitory effect of KLF2. Administration of AKT inhibitor AZD5363 or Insulin-like growth factor-1 (IGF-1) in KLF2 knockdown or ectopic expression cell lines, respectively, substantially reversed the proliferation phenotype. Collectively, our findings provide clinical evidence and a potential mechanism supporting that KLF2 suppresses human gastric tumorigenesis through inhibiting the PTEN/AKT axis.

A novel lncRNA, LL22NC03-N64E9.1, represses KLF2 transcription through binding with EZH2 in colorectal cancer

Long noncoding RNAs (lncRNA) have been implicated in variety human cancer but their mechanisms of function are mainly undocumented. In the present study, we investigated lncRNAs alteration that contributed to colorectal cancer (CRC) by utilizing TCGA RNA sequencing data and other publicly available lncRNAs expression profiling data. Here, We screened out the CRC-associated lncRNA LL22NC03-N64E9.1, a key regulator of CRC development and progression. We also revealed that knockdown of LL22NC03-N64E9.1 inhibited cell proliferation, colony formation, tumorigenicity and apoptosis promotion, both in vitro and in vivo. Mechanistically, LL22NC03-N64E9.1 repressed underlying target gene KLF2 transcription through binding to EZH2. Furthermore, rescue experiments revealed that LL22NC03-N64E9.1 oncogenic function may partially depend on repressing KLF2. Taken together, our results suggested that LL22NC03-N64E9.1 confered an oncogenic function in human CRC and may serve as a candidate prognostic biomarker and target for new therapies in this deadly disease.

KLF15 Inhibits Cell Proliferation in Gastric Cancer Cells via Up-Regulating CDKN1A/p21 and CDKN1C/p57 Expression

BACKGROUND

Krüppel-like factors (KLFs) have been identified in multi-cancers and act as oncogenes or tumor suppressors. The function of KLF15, one member of KLFs, has not been well elucidated, especially in gastric cancer (GC).

AIMS

This study was designed to investigate the prognostic value and biological functions of KLF15 in GC.

METHODS

KLF15 protein expression in GC patients was evaluated by immunohistochemistry assays in 50 paired GC tissues and adjacent normal tissues, and correlations between KLF15 expression and clinicopathological characteristics and prognosis were analyzed. Then, we investigated the over-expression of KLF15 on cell proliferation and its mechanism in GC cells.

RESULTS

KLF15 expression levels were significantly down-regulated in GC tissues compared to adjacent normal tissues. And KLF15 expression was negatively correlated with clinical stage, lymphatic metastasis, and distant metastasis. Furthermore, KLF15 expression could predict prognosis in patients with GC. Moreover, over-expression of KLF15 could inhibit cell proliferation partly via regulating CDKN1A/p21 and CDKN1C/p57.

CONCLUSION

These findings demonstrate that KLF15 plays a significant role in GC progression and could be a therapeutic target for GC.

Over-expressed long noncoding RNA HOXA11-AS promotes cell cycle progression and metastasis in gastric cancer

Background

Long noncoding RNAs (lncRNAs) have emerged as critical regulators in a variety of human cancers, including gastric cancer (GC). However, the function and mechanisms responsible for these molecules in GC are not fully understood. In our previous study, we found that GC associated lncRNA HOXA11-AS is significantly upregulated in GC tissues. Over-expressed HOXA11-AS promotes GC cells proliferation and invasion through scaffolding the chromatin modification factors PRC2, LSD1 and DNMT1.

Methods

HOXA11-AS expression levels in GC cells was detected by quantitative real-time PCR (qPCR). HOXA11-AS siRNAs and overexpression vector were transfected into GC cells to down-regulate or up-regulate HOXA11-AS expression. In vitro and in vivo assays were performed to investigate the functional role of HOXA11-AS in GC cells cell cycle progression, invasion and metastasis. RIP and ChIP assays were used to determine the mechanism of HOXA11-AS’s regulation of underlying targets.

Results

We found that knockdown of HOXA11-AS induced GC cells G0/G1 phase arrest and suppressed GC cells migration, invasion and metastasis in vivo. Moreover, mechanistic investigation showed that HOXA11-AS could interact with WDR5 and promote β-catenin transcription, bind with EZH2 and repress P21 transcription, and induce KLF2 mRNA degradation via interacting with STAU1.

Conclusions

Taken together, these findings show that HOXA11-AS not only could promote GC cells migration and invasion in vitro, but also promotes GC cells metastasis in vivo, at least in part, by regulating β-catenin and KLF2.

Electronic supplementary material

The online version of this article (doi:10.1186/s12943-017-0651-6) contains supplementary material, which is available to authorized users.

The histone demethylase lysine-specific demethylase-1-mediated epigenetic silence of KLF2 contributes to gastric cancer cell proliferation, migration, and invasion

Gastric cancer is one of the most common malignancies and leading causes of cancer-related death worldwide. An increasing number of evidence has revealed that gastric tumorigenesis is a multistage pathological state, and epigenetic alterations are considered to play critical roles in the etiology of gastric cancer. Lysine-specific demethylase-1, a histone demethylase, has been linked to malignancy in several human cancers and considered to epigenetically regulate many tumor suppressor genes during tumorigenesis and cancer progression. However, its role and underlying targets in gastric cancer are still unclear. In this study, we detected the lysine-specific demethylase-1 expression level in gastric cancer tissues and cell lines and investigated the function and mechanism of lysine-specific demethylase-1 in the gastric cancer. The in vitro analysis shows that knockdown of lysine-specific demethylase-1 significantly inhibits gastric cancer cell proliferation, migration, and invasion and induces cell cycle G1 phase arrest and cell apoptosis. In vivo assays determine that lysine-specific demethylase-1 downregulation represses gastric cancer cell tumorigenesis. Mechanistic investigation reveals that tumor suppressor KLF2 is a key downstream target of lysine-specific demethylase-1 in gastric cancer. These findings indicate that lysine-specific demethylase-1 is an important oncogene in gastric cancer, and lysine-specific demethylase-1-mediated epigenetic repression of KLF2 plays a critical role in gastric cancer development and progression, which supports lysine-specific demethylase-1 as a potential therapeutic target in this disease.

Upregulated long non-coding RNA AGAP2-AS1 represses LATS2 and KLF2 expression through interacting with EZH2 and LSD1 in non-small-cell lung cancer cells

Recently, long non-coding RNAs (lncRNAs) are identified as new crucial regulators of diverse cellular processes, including cell proliferation, differentiation and cancer cells metastasis. Accumulating evidence has revealed that aberrant lncRNA expression plays important roles in carcinogenesis and tumor progression. However, the expression pattern and biological function of lncRNAs in non-small-cell lung cancer (NSCLC) remain largely unknown. In this study, we performed comprehensive analysis of lncRNA expression in human NSCLC samples by using microarray data from Gene Expression Omnibus. After validation in a cohort of 80 pairs of NSCLC tissues, we identified a differentially expressed novel oncogenic lncRNA termed as AGAP2-AS1. The AGAP2-AS1 expression level was significantly upregulated in NSCLC tissues and negatively correlated with poor prognostic outcomes in patients. In vitro loss- and gain-of-function assays revealed that AGAP2-AS1 knockdown inhibited cell proliferation, migration and invasion, and induced cell apoptosis. In vivo assays also confirmed the ability of AGAP2-AS1 to promote tumor growth. Furthermore, mechanistic investigation showed that AGAP2-AS1 could bind with enhancer of zeste homolog 2 and lysine (K)-specific demethylase 1A, and recruit them to KLF2 and LATS2 promoter regions to repress their transcription. Taken together, our findings indicate that AGAP2-AS1 may act as an oncogene by repressing tumor-suppressor LATS2 and KLF2 transcription. By clarifying the AGAP2-AS1 mechanisms underlying NSCLC development and progression, these findings might promote the development of novel therapeutic strategies for this disease.

SUZ12 promotes gastric cancer cell proliferation and metastasis by regulating KLF2 and E-cadherin

SUZ12 is a core component of the polycomb repressive complex 2 (PRC2), which could silence gene transcription by generating trimethylation on lysine 27 residue of histone H3 (H3K27Me3). Meanwhile, SUZ12 has been found to be overexpressed in multiple cancers; however, the clinical significance and molecular mechanisms of SUZ12 controlling gastric cancer cell proliferation and metastasis are unclear. In this study, we found that SUZ12 expression was significantly increased in 64 gastric tumor tissues compared with normal tissues. Additionally, SUZ12 expression was associated with pathological stage, metastasis distance, and shorter overall survival of gastric cancer patients. Knockdown of SUZ12 expression impaired cell proliferation and invasion in vitro, leading to the inhibition of metastasis in vivo. Upregulation of SUZ12 was found to play a key role in gastric cancer cell proliferation and metastasis through the regulation of EMT and KLF2 expression.