The long noncoding RNA TPTE2P1 promotes the viability of colorectal cancer cells

Long noncoding RNAs (lncRNAs) have important functions in tumor development and progression, including colorectal cancer (CRC), but their roles are not completely understood. In this study, the roles of the lncRNA transmembrane phosphoinositide 3-phosphatase and tensin homolog 2 pseudogene 1 (TPTE2P1), previously implicated in gallbladder cancer cell migration and invasion, were evaluated in CRC. In particular, quantitative polymerase chain reaction was used to quantify TPTE2P1 levels in tumor tissues and cell lines. The association between TPTE2P1 and survival was analyzed using the online tool OncoLnc. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assays, colony formation assays, and flow cytometry were used to evaluate the effects of TPTE2P1 on viability, cell cycle progression, and apoptosis. Signaling pathway proteins were quantitated by Western blot analysis. Finally, the role of TPTE2P1 was analyzed in vivo using mouse models. TPTE2P1 levels were significantly higher in CRC tissues than in adjacent normal tissues. Higher expression was associated with a poor survival rate. The silencing of TPTE2P1 led to cell cycle arrest at the S phase and thereby inhibited cell viability. TPTE2P1 knockdown also caused cancer cell apoptosis via the activation of the apoptosis regulator (BCL2)/caspase 3 signaling cascade. In addition, the inhibition of TPTE2P1 had suppressive effects on tumors in vivo. TPTE2P1 is upregulated in CRC and plays essential roles in the regulation of cell viability in vitro and tumor formation in vivo.     

Long noncoding RNA lnc-sox5 modulates CRC tumorigenesis by unbalancing tumor microenvironment

Long non-coding RNAs (LncRNAs) have been recently regarded as systemic regulators in multiple biologic processes including tumorigenesis. In this study, we observed the expression of lncRNA lnc-sox5 was significantly increased in colorectal cancer (CRC). Despite the CRC cell growth, cell cycle and cell apoptosis was not affected by lnc-sox5 knock-down, lnc-sox5 knock-down suppressed CRC cell migration and invasion. In addition, xenograft animal model suggested that lnc-sox5 knock-down significantly suppressed the CRC tumorigenesis. Our results also showed that the expression of indoleamine 2,3-dioxygenase 1 (IDO1) was significantly reduced by lnc-sox5 knock-down and therefore modulated the infiltration and cytotoxicity of CD3⁺CD8⁺T cells. Taken together, these results suggested that lnc-sox5 unbalances tumor microenvironment to regulate colorectal cancer progression.     

LncRNA Linc00511 promotes osteosarcoma cell proliferation and migration through sponging miR-765

Long noncoding RNA (lncRNA) Linc00511 is a novel lncRNA, and it was reported to play important roles in the progression and carcinogenesis of several tumors. However, the expression and biological roles of Linc00511 in osteosarcoma were still unknown. In this research, we showed that the expression of Linc00511 was upregulated in osteosarcoma samples and cell lines. Ectopic expression of Linc00511 promoted osteosarcoma cell growth, colony formation, and migration. Moreover, overexpression of Linc00511 enhanced the epithelial-mesenchymal transition progression in osteosarcoma cell. In addition, we showed that elevated expression of Linc00511 suppressed microRNA-765 (miR-765) expression and promoted apurinic/apyrimidinic endonuclease 1 (APE1) expression in osteosarcoma cell. The expression of miR-765 was downregulated in osteosarcoma cells and samples and was negatively related to Linc00511 expression in osteosarcoma tissues. Ectopic expression of miR-765 inhibited osteosarcoma cell growth and migration. Furthermore, we showed that Linc00511 overexpression promoted MG-63 cells proliferation, colony formation, and migration via downregulation of miR-765. These results suggested that Linc00511 played as an oncogene in the development of osteosarcoma.     

Long noncoding RNA OIP5-AS1 aggravates cell proliferation,migration in gastric cancer by epigenetically silencing NLRP6 expression via binding EZH2

The critical role of long noncoding RNAs (lncRNAs) in the development of multiple cancers has been revealed either functioning as a tumor initiator or a cancer suppressor. A widely recognized OIP5 antisense RNA 1 (lncRNA OIP5-AS1) has been validated to be an essential regulator of the tumorigenesis of various malignancies. Whereas, the potential role and the exact mechanism of lncRNA OIP5-AS1 by which OIP5-AS1 mediates gastric cancer (GC) progression remains vague. Therefore, first our work probed its expression levels in GC cell lines and related normal cells by real-time quantitative polymerase chain reaction. The heightened level of OIP5-AS1 was detected in GC cell lines. In terms of its cellular effects, we performed a series of functional experiments and as presented in the assays, the proliferative potential and motility was diminished. However, more apoptotic cells were induced with the introduction of OIP5-AS1 silencing. Meanwhile, higher Nod-like receptor pyrin domain-containing protein 6 (NLRP6) and enhancer of zeste homolog 2 (EZH2) expression in the GC cells was monitored. Besides, OIP5-AS1 was disclosed to locate mainly in the nucleus. In terms of mechanism, OIP5-AS1 directly bound to EZH2 and obstructed NLRP6 expression, speeding up GC progression.     

H3K27 acetylation-induced lncRNA EIF3J-AS1 improved proliferation and impeded apoptosis of colorectal cancer through miR-3163/YAP1 axis

Long noncoding RNAs (lncRNAs) are found to be aberrantly expressed and pose significant impacts in colorectal cancer (CRC), the most prevalent type malignancy in the gastrointestinal tract. This study aimed to find out the regulation of lncRNA EIF3J antisense RNA 1 (EIF3J-AS1) on CRC progression. Expressions of EIF3J-AS1, microRNA-3163 (miR-3163), and Yes-associated protein 1 (YAP1) in tissues and cells were evaluated by real-time quantitative polymerase chain reaction (RT-qPCR) and Western blot analysis. Association of EIF3J-AS1 with CRC prognosis was analyzed through the online bioinformatics tool GEPIA. The biological function of EIF3J-AS1 in CRC was investigated by Cell Counting Kit-8, colony formation, caspase-3 activity, and TUNEL staining. Competitive endogenous RNA (ceRNA) network of EIF3J-AS1/miR-3163/YAP1 was determined by luciferase reporter and RNA immunoprecipitation assays. Results showed that EIF3J-AS1 was upregulated in CRC tissues and cell lines, indicating poor prognosis of CRC patients. The silence of EIF3J-AS1 led to reduced proliferation and facilitated apoptosis of CRC cells. Mechanistcally, EIF3J-AS1 was upregulated by cAMP-response element-binding protein-binding protein-mediated histone H3 on lysine 27 acetylation (H3K27ac) at the promoter region, and EIF3J-AS1 upregulated YAP1 expression through sponging miR-3163 in CRC cells. In conclusion, we first found that H3K27 acetylation-induced lncRNA EIF3J-AS1 improved proliferation and impeded apoptosis of colorectal cancer through the miR-3163/YAP1 axis, which might potentially provide a novel molecular-targeted strategy for CRC treatment.     

Retracted: Long noncoding RNA TALNEC2 plays an oncogenic role in breast cancer by binding to EZH2 to target p57KIP2 and involving in p-p38 MAPK and NF-κB pathways

We aimed to investigate the potential role and regulatory mechanism of long noncoding RNA tumor-associated lncRNA expressed in chromosome 2 (TALNEC2) in breast cancer. The expression of TALNEC2 in breast cancer tissues and cells were investigated. MCF-7 and MDA-MB-231 cells were transfected with small interfering RNA (siRNA) duplexes for targeting TALNEC2 (si-TALNEC2), enhancer of zeste homolog 2 (EZH2; si-EZH2) and p57^KIP2 (si-p57 ^KIP2), and their corresponding controls (si-NC). The viability, colony forming ability, cell cycle, apoptosis, and autophagy of transfected cells were assessed. The expressions of p-p38 mitogen-activated protein kinase (MAPK) and nuclear factor κB (NF-κB) pathway-related proteins were investigated. The results showed that TALNEC2 was highly expressed in breast cancer tissues and cells. Knockdown of TALNEC2 significantly inhibited the malignant behaviors of MCF-7 and MDA-MB-231 cells, including inhibiting cell viability and colony forming, arresting cell cycle at G0/G1 phase, inducing cell apoptosis, and promoting cell autophagy. EZH2 was a TALNEC2 binding protein, which was upregulated in breast cancer tissues and cells and could negatively regulate p57 ^KIP2. Effects of TALNEC2 knockdown on malignant behaviors of MCF-7 cells were reversed by p57 ^KIP2 knockdown. The expressions of p-p38, RelA, and RelB in MCF-7 cells were decreased after knockdown of TALNEC2 or EZH2, which were reversed by knockdown of p57 ^KIP2 concurrently. In conclusion, TALNEC2 may play an oncogenic role in breast cancer by binding to EZH2 to target p57 ^KIP2. Activation of p-p38 MAPK and NF-κB pathways may be key mechanisms mediating the oncogenic role of TALNEC2 in breast cancer. TALNEC2 may serve as a promising target in the therapy of breast cancer.     

Long noncoding RNA HIT000218960 promotes papillary thyroid cancer oncogenesis and tumor progression by upregulating the expression of high mobility group AT-hook 2 (HMGA2) gene

Accumulating evidence suggests that long noncoding RNAs (lncRNAs) play an important role in oncogenesis and tumor progression. However, our knowledge of lncRNAs in thyroid cancer is still limited. To explore the crucial lncRNAs involved in oncogenesis of papillary thyroid cancer (PTC), we acquired data of differentially expressed lncRNAs between PTC tissues and paired adjacent noncancerous thyroid tissues through lncRNA microarray. In the microarray data, we observed that a newly identified lncRNA, HIT000218960, was significantly upregulated in PTC tissues and associated with a well-known oncogene, high mobility group AT-hook 2 (HMGA2) gene. Both in normal thyroid tissues and PTC tissues, the expression of HIT000218960 was significantly positively correlated with that of HMGA2 mRNA. Knockdown of HIT000218960 in PTC cells resulted in downregulation of HMGA2. In addition, functional assays indicated that inhibition of HIT000218960 in PTC cells suppressed cell proliferation, colony formation, migration and invasion in vitro. Increased HIT000218960 expression in PTC tissues was obviously correlated with lymph node metastasis and multifocality, as well as TNM stage. Those findings suggest that HIT000218960 might acts as a tumor promoter through regulating the expression of HMGA2.     

miR-154 suppresses colorectal cancer cell growth and motility by targeting TLR2

MicroRNAs play critical roles in the development and progression of colorectal cancer (CRC). miR-154 acts as a tumor suppressor in several tumors; however, its role in CRC is poorly understood. Herein, we found that miR-154 was decreased in CRC tissues and cell lines. Ectopic expression of miR-154 remarkably suppressed cell proliferation and colony formation, migration and invasion in CRC cells. The toll-like receptor 2 (TLR2) was found to be a direct target of miR-154 in CRC cells. Inhibition of TLR2 performed similar effects with miR-154 overexpression on CRC cells, and overexpression of TLR2 could significantly reverse the tumor suppressive effects of miR-154 on CRC cells. This study suggests an essential role for miR-154 in CRC.     

Possible role of Pax-6 in promoting breast cancer cell proliferation and tumorigenesis

Pax 6, a member of the paired box (Pax) family, has been implicated in oncogenesis. However, its therapeutic potential has been never examined in breast cancer. To explore the role of Pax6 in breast cancer development, a lentivirus based short hairpin RNA (shRNA) delivery system was used to knockdown Pax6 expression in estrogen receptor (ER)-positive (MCF-7) and ER-negative (MDA-MB-231) breast cancer cells. Effect of Pax6 silencing on breast cancer cell proliferation and tumorigenesis was analyzed. Pax6-RNAi-lentivirus infection remarkably downregulated the expression levels of Pax6 mRNA and protein in MCF-7 and MDA-MB-231 cells. Accordingly, the cell viability, DNA synthesis, and colony formation were strongly suppressed, and the tumorigenesis in xenograft nude mice was significantly inhibited. Moreover, tumor cells were arrested at G0/G1 phase after Pax6 was knocked down. Pax6 facilitates important regulatory roles in breast cancer cell proliferation and tumor progression, and could serve as a diagnostic marker for clinical investigation.     

LncRNA HOTAIR regulates the expression of E-cadherin to affect nasopharyngeal carcinoma progression by recruiting histone methylase EZH2 to mediate H3K27 trimethylation

Background/AimThere has been increasing evidence for the function of long non-coding RNA (lncRNA) in nasopharyngeal carcinoma (NPC). We aim to delve into the position of lncRNA HOX antisense intergenic RNA (HOTAIR), together with enhancer of zeste homolog 2 (EZH2), E-cadherin and trimethylation of lysine 27 on histone H3 (H3K27me3) in NPC.MethodsHOTAIR, EZH2, and E-cadherin expression in NPC tissues and cells were tested. NPC cell biological functions were examined through gain-of and loss-of function assays. The mechanism of lncRNA HOTAIR/E-cadherin/EZH2/H3K27 axis in NPC was decoded.ResultsLncRNA HOTAIR and EZH2 were highly expressed in NPC, and E-cadherin was lowly expressed. Down-regulation of HOTAIR or EZH2 inhibited NPC cell progression and tumor growth. HOTAIR recruited histone methylase EZH2 to mediate trimethylation of H3K27 and regulated E-cadherin expression.ConclusionHOTAIR inhibits E-cadherin by stimulating the trimethylation of H3K27 to promote NPC cell progression through recruiting histone methylase EZH2.     

LncRNA HAND2-AS1 inhibits 5-fluorouracil resistance by modulating miR-20a/PDCD4 axis in colorectal cancer

BackgroundChemoresistance is one of the main obstacles in the therapy of human cancers, including colorectal cancer (CRC). Long non-coding RNA heart and neural crest derivatives expressed 2-antisense RNA 1 (lncRNA HAND2-AS1) has been demonstrated to be associated with CRC. However, the function of HAND2-AS1 in 5-Fluorouracil (5-FU) resistance of CRC remains unclear.MethodsQuantitative real-time polymerase chain reaction (qRT-PCR) was performed to detect the expression of HAND2-AS1, miR-20a and programmed cell death factor 4 (PDCD4) mRNA. 3-(4, 5-dimethyl-2-thiazolyl)-2, 5-diphenyl-2-H-tetrazolium bromide (MTT) assay was conducted to evaluate IC50 of 5-FU and cell proliferation. Flow cytometry analysis was used to determine cell apoptosis. Transwell assay was carried out to measure cell migration and invasion. Western blot assay was conducted to examine the protein levels of B-cell lymphoma-2 (Bcl-2), BCL2-Associated X (Bax), matrix metalloprotein 2 (MMP2), MMP9 and PDCD4. Dual-luciferase reporter assay, RNA immunoprecipitation (RIP) assay and RNA pull down assay were utilized to verify the combination between miR-20a and HAND2-AS1. Dual-luciferase reporter assay was used to analyze the association between miR-20a and PDCD4. Murine xenograft assay was used to confirm the function of HAND2-AS1 in vivo.ResultsHAND2-AS1 and PDCD4 were downregulated and miR-20a was upregulated in 5-FU-resistant CRC tissues and cells. HAND2-AS1 suppressed 5-FU resistance, cell proliferation, migration and invasion and promoted cell apoptosis in 5-FU-resistant CRC cells. HAND2-AS1 acted as a sponge of miR-20a to regulate PDCD4 expression. Moreover, HAND2-AS1 suppressed cell progression and 5-FU resistance by upregulating PDCD4 via sponging miR-20a in 5-FU-resistant CRC cells. Besides, HAND2-AS1 inhibited tumor growth in vivo.ConclusionHAND2-AS1/miR-20a/PDCD4 axis inhibited cell progression and 5-FU resistance in 5-FU-resistant CRC cells.     

Tumor-suppressive function of EZH2 is through inhibiting glutaminase

Tumors can use metabolic reprogramming to survive nutrient stress. Epigenetic regulators play a critical role in metabolic adaptation. Here we screened a sgRNA library to identify epigenetic regulators responsible for the vulnerability of colorectal cancer (CRC) cells to glucose deprivation and found that more EZH2-knockout cells survived glucose deprivation. Then, we showed that EZH2 expression was significantly downregulated in response to glucose deprivation in a glucose-sensitive CRC cell line, and EZH2-knockdown cells were more resistant to glucose deprivation. Mechanistically, EZH2 deficiency upregulated the expression of glutaminase (GLS) and promoted the production of glutamate, which in turn led to increased synthesis of intracellular glutathione (GSH) and eventually attenuated the reactive oxygen species (ROS)-mediated cell death induced by glucose deprivation. Although EZH2 functioned as an oncogene in cancer progression and EZH2 knockout abolished colorectal cancer development in a mouse model, here we revealed a mechanistic link between EZH2 and metabolic reprogramming via the direct regulation of GLS expression and observed a negative correlation between EZH2 and GLS expression in colorectal cancer tissues. These findings further confirmed the importance of heterogeneity, provided an explanation for the clinical tolerance of cancer cells to EZH2 inhibitors from the perspective of metabolism, and proposed the possibility of combining EZH2 inhibitors and glutamine metabolism inhibitors for the treatment of cancer.Subject terms: Cancer metabolism, Colon cancer     

UNC5B‐AS1 promoted ovarian cancer progression by regulating the H3K27me on NDRG2 via EZH2

The role of long non‐coding RNAs (lncRNAs) in tumorigenesis and development of ovarian cancer (OC) has caught the attention of scientists. UNC5B antisense RNA 1 (UNC5B‐AS1) is a newly identified carcinogenic lncRNA in thyroid papillary carcinoma, but its role in OC remains unclear. This study is proposed to investigate the function and mechanism of UNC5B‐AS1 in OC. UNC5B‐AS1 expression in OC samples was obtained from gene expression profiling interactive analysis (GEPIA) based on The Cancer Genome Atlas data. Gene expressions were detected by quantitative real‐time polymerase chain reaction (RT‐qPCR) and western blot. Biological functions of UNC5B‐AS1 were assessed by cell counting kit‐8, colony formation, and caspase‐3 analysis. GEPIA revealed the UNC5B‐AS1 upregulation in OC samples. RT‐qPCR assay confirmed the upregulation of UNC5B‐AS1 in OC cells. Functionally, depletion of UCN5B‐AS1 hindered proliferation and prompted apoptosis in OC cells. Mechanistically, we found that UNC5B‐AS1 interacted with zeste 2 polycomb repressive complex 2 subunit (EZH2) to trigger trimethylation of histone H3 at lysine 27 (H3K27me3) on N‐myc downstream regulated gene‐2 (NDRG2) promoter and epigenetically repressed NDRG2. Rescue assay indicated the participation of NDRG2 in the regulation of UNC5B‐AS1 on OC progression. Together, we first illustrated that UNC5B‐AS1 promoted OC progression by regulating the H3K27me on NDRG2 via EZH2, indicating UNC5B‐AS1 as a potential molecular target for OC treatment.     

Long non-coding RNA ZFAS1 regulates the malignant progression of gastric cancer via the microRNA-200b-3p/Wnt1 axis

Gastric cancer is a common malignant tumor. Studies from our laboratory or others have shown that long non-coding RNA (lncRNA) zinc finger antisense (ZFAS)1 often acts as an oncogene. However, the molecular underpinnings of how ZFAS1 regulates gastric cancer remain to be elucidated. Results showed that ZFAS1 expression was upregulated, and microRNA-200b-3p (miR-200b) expression was downregulated in gastric cancer tissues. MiR-200b overexpression suppressed the proliferation, cell cycle process, and Wnt/β-catenin signaling of gastric cancer cells. Subsequently, we identified miR-200b is a target of ZFAS1 and Wnt1 is a target of miR-200b. Furthermore, promotion of cancer malignant progression and activation of Wnt/β-catenin signaling induced by ZFAS1 was counteracted by increasing miR-200b expression. In vivo, ZFAS1 knockdown suppressed the tumorigenesis with the upregulated miR-200b and the inactive Wnt/β-catenin signaling. Summarily, we demonstrated a critical role of miR-200b in gastric cancer, and ZFAS1 can promote malignant progression through regulating miR-200b mediated Wnt/β-catenin signaling.