PCAT6 participates in the development of gastric cancer through endogenously competition with microRNA-30

Epithelial-mesenchymal transition-related long noncoding RNAs in gastric carcinoma

As an evolutionarily phenotypic conversion program, the epithelial-mesenchymal transition (EMT) has been implicated in tumour deterioration and has facilitated the metastatic ability of cancer cells via enhancing migration and invasion. Gastric cancer (GC) remains a frequently diagnosed non-skin malignancy globally. Most GC-associated mortality can be attributed to metastasis. Recent studies have shown that EMT-related long non-coding RNAs (lncRNAs) play a critical role in GC progression and GC cell motility. In addition, lncRNAs are associated with EMT-related transcription factors and signalling pathways. In the present review, we comprehensively described the EMT-inducing lncRNA molecular mechanisms and functional perspectives of EMT-inducing lncRNAs in GC progression. Taken together, the statements of this review provided a clinical implementation in identifying lncRNAs as potential therapeutic targets for advanced GC.

PCAT6 May Be a Whistler and Checkpoint Target for Precision Therapy in Human Cancers

Simple Summary

Prostate cancer-associated transcript 6 (PCAT6), as a newly discovered carcinogenic long non-coding RNA (lncRNA), is abnormally expressed in multiple diseases. With the accumulation of studies on PCAT6, we have a deeper understanding of its biological functions and mechanisms. Therefore, in this review, the various molecular mechanisms by which PCAT6 promotes multiple tumorigenesis and progression are summarized and discussed. Furthermore, its potential diagnostic, prognostic, and immunotherapeutic values are also clarified.

Abstract

LncRNAs are involved in the occurrence and progressions of multiple cancers. Emerging evidence has shown that PCAT6, a newly discovered carcinogenic lncRNA, is abnormally elevated in various human malignant tumors. Until now, PCAT6 has been found to sponge various miRNAs to activate the signaling pathways, which further affects tumor cell proliferation, migration, invasion, cycle, apoptosis, radioresistance, and chemoresistance. Moreover, PCAT6 has been shown to exert biological functions beyond ceRNAs. In this review, we summarize the biological characteristics of PCAT6 in a variety of human malignancies and describe the biological mechanisms by which PCAT6 can facilitate tumor progression. Finally, we discuss its diagnostic and prognostic values and clinical applications in various human malignancies.

SLCO4A1-AS1 Facilitates the Malignant Phenotype via miR-149-5p/STAT3 Axis in Gastric Cancer Cells

Solute carrier organic anion transporter family member 4A1 (SLCO4A1-AS1), a newly discovered lncRNA, may exert effects in tumors. Since its role in gastric cancer remains obscure, we sought to explore the mechanism of SLCO4A1-AS1 in gastric cancer. The relationship among SLCO4A1-AS1, miR-149-5p, and STAT3 was detected by bioinformatics, dual luciferase analysis, and Pearson's test, and the expressions of these genes were determined by quantitative real-time PCR and Western blot. Moreover, CCK-8, flow cytometry, wound healing assay, and Transwell analysis were performed to verify the function of SLCO4A1-AS1 in gastric cancer. Rescue experiments were used to detect the role of miR-149-5p. The expressions of SLCO4A1-AS1 and STAT3 were increased, while the expression of miR-149-5p was suppressed in gastric cancer tissues and cell lines. In addition, STAT3 expression was negatively correlated with miR-149-5p expression but was positively correlated with SLCO4A1-AS1 expression. Overexpression of SLCO4A1-AS1 promoted cell viability, migration, invasion, and STAT3 expression but suppressed apoptosis, while knockdown of SLCO4A1-AS1 had the opposite effect. SLCO4A1-AS1 bound to miR-149-5p and targeted STAT3. Moreover, miR-149-5p mimic inhibited the malignant development of gastric cancer cells and obviously reversed the function of SLCO4A1-AS1 overexpression. Our research reveals that abnormally increased SLCO4A1-AS1 expression may be an important molecular mechanism in the development of gastric cancer.

Elevated expression of MKRN3 in squamous cell carcinoma of the head and neck and its clinical significance

BACKGROUND

Squamous cell carcinoma of the head and neck (SCCHN) is one of the most common types of cancer that cause a substantial number of cancer-related deaths. Our previous study has revealed that makorin ring finger protein 3 (MKRN3) may act as a key regulator of the SCCHN tumorigenesis; however, its specific role in SCCHN progression has not been reported.

METHODS

The Cancer Genome Atlas (TCGA) data analysis and quantitative polymerase chain reaction (qPCR) were used to quantify the MKRN3 mRNA expression levels in SCCHN; immunohistochemical staining or immunoblotting analyses were performed to detect MKRN3 protein expression. Kaplan-Meier plotter was used to assess the prognostic values of MKRN3 in terms of overall survival and disease-free survival. The expression differences based on various clinicopathological features were evaluated using subgroup analysis and forest map analysis. The regulatory mechanism of MKRN3 was further investigated using gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses. Subsequently, STRING was used to perform a co-expression and enrichment analysis for MKRN3. Homologous modeling, molecular docking, and western blot analyses were performed to investigate the relationship between MKRN3 and its potential target gene P53.

RESULTS

MKRN3 was ectopically expressed between cancerous and noncancerous SCCHN tissues, and its expression level was tightly associated with high T classifications as well as advanced clinical stages. qPCR analysis revealed that MKRN3 was upregulated in the SCCHN cell line. Moreover, Kaplan-Meier and Cox regression analyses indicated that SCCHN patients with high MKRN3 expression had poorer prognosis and that MKRN3 was a potential prognostic marker for SCCHN. Using gene ontology and Kyoto Encyclopedia of Genes and Genomes analyses, we determined that MKRN3 may be involved in the regulation of synthesis and metabolism and cell growth, death and motility, as well as cancer pathways associated with SCCHN progression. Mechanism investigation further revealed that P53, a potential target of MKRN3, may be involved in the SCCHN tumorigenesis mediated by MKRN3.

CONCLUSIONS

We performed a comprehensive evaluation of the clinical significance of MKRN3 and explored its underlying mechanisms. We concluded that MKRN3 represents a valuable predictive biomarker and potential therapeutic target in SCCHN.

The Role of lncRNA PCAT6 in Cancers

Long non-coding RNA (lncRNA) PCAT6 is a member of the Prostate Cancer Associated Transcripts family of molecules. In this review, we focus on the latest studies involving PCAT6 in the diagnosis, treatment, and prognosis of malignant tumors of the digestive, respiratory, urinary, reproductive, motion, and nervous systems. PCAT6 was found to be highly expressed in gastric cancer, colon cancer, hepatocellular carcinoma, lung cancer, bladder cancer, ovarian cancer, breast cancer, cervical cancer, osteosarcoma, glioblastoma, and other tumors. PCAT6 can promote the development and progression of different types of malignant tumors through various mechanisms. Overall, these findings suggest that PCAT6 may play an increasingly vital role in the clinical assessment of these malignant tumors. It can function as an oncogene and may be used as a potential new prognostic biomarker of these tumors.

PCAT6 may be a new prognostic biomarker in various cancers: a meta-analysis and bioinformatics analysis

Background

LncRNA prostate cancer-associated transcript 6 (PCAT6) has been reported to be dysregulated in several cancers and is associated with tumor progression. Here, we have performed a meta-analysis to assess the general prognostic role of PCAT6 in malignancies.

Methods

Four public databases (Embase, Pubmed, Web of Science, Cochrane Library) were used to identify eligible studies, then data was extracted and associations between prognostic indicators and clinical characteristics were combined to estimate hazard ratio (HR) or odds ratio (OR) with a 95% confidence interval (CI). Publication bias was measured using the Begg's test, and the stability of the combined results was measured using sensitivity analysis. Subsequently, results were validated using Gene Expression Profiling Interactive Analysis (GEPIA) and the National Genomics Data Center (NGDC).

Results

Ten studies were considered eligible for inclusion. In total, 937 patients and eight types of cancer were included. Our results revealed that overexpression of PCAT6 was significantly associated with a shorter OS (HR = 1.82; 95% CI, [1.40, 2.38]; P < 0.0001) and progression-free survival (PFS) (HR = 1.66; 95% CI, [1.22, 2.25]; P < 0.0001) in cancer patients, and that PCAT6 overexpression was significantly associated with individual tumor clinicopathological parameters, including TNM stage (OR = 0.29; 95% CI, [0.09, 0.94]; P = 0.04), gender (OR = 1.84; 95% CI, [1.31, 2.59]; P = 0.0005), and whether the tumor was metastatic (OR = 5.02; 95% CI, [1.36, 18.57]; P = 0.02). However, PCAT6 overexpression was not correlated with patient age and tumor differentiation. PCAT6 expression was significantly up-regulated in four types of cancer, which was validated using the GEPIA cohort. Combining OS and disease-free survival (DFS) of these four types of cancer revealed a shorter OS and DFS in patients with PCAT6 overexpression. PCAT6 expression in various types of cancer was also validated in NGDC. A total of eight cancers were analyzed and PCAT6 was highly expressed in all eight cancers. Further functional predictions suggest that PCAT6 is correlated with tumor prognosis, and that PCAT6 may be useful as a new tumor-specific marker.

Conclusions

LncRNA PCAT6 is highly expressed in multiple cancer types and its upregulation was significantly associated with patient prognosis and poorer clinical features, thereby suggesting that PCAT6 may be a novel prognostic factor in multiple cancer types.

Enzalutamide-Induced Upregulation of PCAT6 Promotes Prostate Cancer Neuroendocrine Differentiation by Regulating miR-326/HNRNPA2B1 Axis

Our previous studies have demonstrated that Enzalutamide-induced upregulation of long non-coding RNA p21 (lncRNA-p21) facilitates prostate cancer (PCa) neuroendocrine differentiation (NED). Given the important role of lncRNAs in PCa pathogenesis, and given that lots of lncRNAs are dys-regulated in neuroendocrine PCa (NEPC) patients, we next explored the biological function and underlying mechanism of lncRNA-PCAT6 (PCAT6) in mediating Enzalutamide-induced NED. The level of PCAT6 in Enzalutamide-treated PCa cells and NEPC samples were assessed using quantitative RT-PCR (qPCR). The effect of PCAT6 on PCa cell proliferation, invasion, and NED was evaluated through CCK-8, transwell, qPCR, western blot analysis, Xenograft mouse model, and in vivo lung metastasis model. We found that PCAT6 was highly expressed in NE-like cells (PC3, DU145, and NCI-H660) compared with androgen-sensitive LNCaP cells. PCAT6 was also highly expressed in NEPC tissues. Enzalutamide treatment resulted in a significant increase of PCAT6 level in a dose- and time-dependent fashion. Functionally, PCAT6 overexpression promoted NED of C4-2 cells, as evidenced by an increased expression of NE markers (NSE, ChgA, and SYP), whereas PCAT6 knockdown in NCI-H661 cells repressed NED. Furthermore, PCAT6 overexpression promoted PCa cell proliferation and invasion in vitro and in vivo. Mechanistically, PCAT6 functioned as competing endogenous (ce) RNA via absorbing miR-326, thus resulting in a de-suppression of Hnrnpa2b1 target gene. The current results demonstrate that PCAT6 acted as a tumor activator in PCa progression by sponging miR-326 and increasing Hnrnpa2b1 expression and that the PCAT6/miR-326/Hnrnpa2b1 signaling might be a new therapeutic target for PCa.

The Cancer-Testis Long Non-coding RNA PCAT6 Facilitates the Malignant Phenotype of Ovarian Cancer by Sponging miR-143-3p

Background: It has been reported that long non-coding RNAs (lncRNAs) play critical roles in tumorigenesis. However, their roles in ovarian cancer (OC) remain to be elucidated. The aim of this study was to uncover the function and underlying mechanisms of PCAT6 in OC.

Methods: The expression pattern of PCAT6 in OC was analyzed in the GSE137238, GSE143897 and Gene Expression Profile Interactive Analysis (GEPIA) datasets. Kaplan–Meier Plotter online software was used for survival analysis. Loss-of-function assays and gain-of-function assays were used to assess the function of PCAT6 in OC development. Moreover, small-RNA sequencing, bioinformatic analysis, luciferase assays and rescue experiments were carried out to clarify the potential mechanism of PCAT6 in OC.

Results: PCAT6 expression was significantly increased in OC tissues and positively correlated with advanced stages and with poor overall survival, progression-free survival and post-progression survival. Knockdown of PCAT6 in A2780 and SKOV3 cells inhibited OC cell proliferation, migration and invasion. In contrast, Overexpression of PCAT6 exerted the opposite effects on OC cells. Notably, PCAT6 bound to miR-143-3p and affected the expression of transforming growth factor (TGF)-β-activated kinase 1 (TAK1). Subsequent rescue assays confirmed that upregulation of miR-143-3p decreased the PCAT6 overexpression-induced promotion of proliferation, migration and invasion. Moreover, downregulation of miR-143-3p reversed the PCAT6 knockdown-induced inhibition of proliferation, migration, and invasion.

Conclusions: Our findings demonstrate that PCAT6 plays an oncogenic role in OC and may be useful as a therapeutic target for OC.

Long Non-Coding RNA PCAT6 Induces M2 Polarization of Macrophages in Cholangiocarcinoma via Modulating miR-326 and RhoA-ROCK Signaling Pathway

LncRNAs can act crucial roles in multiple tumors including cholangiocarcinoma (CCA). M2 polarization of macrophages is crucial for their biological roles in immunologic tolerance, which is able to induce tumorigenesis. Given that increasing evidence have suggested that lncRNAs could participate in modulating immune cell differentiation and function. Our current study was aimed to identify the underlying mechanism of lncRNA prostate cancer-associated transcript 6 (PCAT6) in CCA progression via regulating M2 macrophage polarization. PCAT6 has been reported as an oncogene in many cancers. In our work, we observed increased expression of PCAT6 in CCA patients. PCAT6 expression in various types of immune cells derived from CCA patients was tested by quantitative real-time PCR (qRT-PCR). It was revealed that PCAT6 was highly expressed in macrophages, which indicated that PCAT6 might regulate the function of macrophages to promote CCA progression. Then, via establishing CCA xenograft mouse model, we found loss of PCAT6 obviously triggered the immune response and reduced the in vivo tumor growth. In addition, overexpression of PCAT6 led to the M2 polarization of THP-1-differentiated macrophages. Moreover, miR-326 was predicted and proved as a target for PCAT6. In addition, down-regulation of PCAT6 repressed M2 polarization of macrophages, which was reversed by miR-326 inhibitors. The increase of PCAT6 induced the accumulation of ROS, mitochondrial and metabolic dysfunction in macrophages and mimics of miR-326 exhibited an opposite process. RohA has been recognized as a significant regulator of immune cell function. In our current work, we observed that RohA function as a downstream target for miR-326. In conclusion, our study highlighted a significant role of PCAT6/miR-326/RohA in immune response of macrophages in CCA and indicated PCAT6 as a potential target of immunotherapy in CCA.

Long-Noncoding RNA PCAT6 Aggravates Osteosarcoma Tumourigenesis via the MiR-143-3p/ZEB1 Axis

Introduction

The long-noncoding RNA PCAT6 plays an important regulatory role in the development of several cancers. However, the expression pattern and underlying mechanisms of PCAT6 in osteosarcoma (OS) are yet unknown.

Methods

We used real-time PCR to measure PCAT6 expression in 106 tumor pairs and corresponding non-tumor tissues from OS patients. Statistical analyses were applied to evaluate the prognostic value and associations of PCAT6 expression with clinical parameters. Furthermore, the PCAT6 was silenced with siRNA in OS cells. Moreover, phenotype of PCAT6 silenced OS cells was measured using colony formation, CCK-8, cell migration and invasion assay. Finally, the molecular mechanism of PCAT6/miR-143-3p/ZEB1 axis in OS progression was explored.

Results

The expression level of PCAT6 in OS tissues was significantly elevated as compared with that in the adjacent normal bone tissues and that high PCAT6 expression closely correlated with the malignant phenotype and poor survival among patients with OS. Multivariate analyses revealed PCAT6 overexpression as an independent prognostic factor for the poor outcome of patients with OS. Functional assay results demonstrated that the knockdown of PCAT6 expression notably suppressed the proliferation, migration, and invasion of OS cells. An elevated PCAT6 level aggravated the malignant phenotype of OS cells via ZEB1 expression upregulation. Mechanistic studies revealed that PCAT6 could sponge endogenous miR-143-3p and inhibit its activity, resulting in an increase in ZEB1 level. Finally, we demonstrated that the tumour-promoting role of PCAT6 in OS was dependent on the regulation of the miR-143-3p/ZEB1 axis.

Conclusion

These findings highlight the potential role of PCAT6, which could serve as a valuable prognostic indicator for patients with OS.

Knockdown of lncRNA PCAT6 Enhances Radiosensitivity in Triple-Negative Breast Cancer Cells by Regulating miR-185-5p/TPD52 Axis

Background

Long non-coding RNAs (lncRNAs) have been reported to play essential roles in regulating the radiosensitivity of cancers. Prostate cancer-associated transcript 6 (PCAT6) exerts oncogenic roles in several tumors. However, the roles of PCAT6 and its underlying mechanism in regulating the radiosensitivity of triple-negative breast cancer (TNBC) have not been investigated.

Methods

The expression levels of PCAT6, microRNA-185-5p (miR-185-5p) and tumor protein D52 (TPD52) were determined by quantitative real-time polymerase chain reaction (qRT-PCR). Cell viability, apoptosis and colony formation were assessed by Cell Counting Kit-8 (CCK-8) assay, flow cytometry and colony formation assay, respectively. The interaction between miR-185-5p and PCAT6 or TPD52 was predicted by bioinformatics analysis and verified by dual-luciferase reporter assay. Western blot was carried out to detect the protein level of TPD52.

Results

PCAT6 and TPD52 were highly expressed and miR-185-5p was lowly expressed in TNBC tissues and cells, which was associated with an aggressive tumor phenotype in patients, affecting lymph node metastasis and clinical stage. PCAT6 or TPD52 knockdown or miR-185-5p overexpression enhanced the radiosensitivity of TNBC cells via inhibiting proliferation and inducing apoptosis. PCAT6 directly interacted with miR-185-5p and negatively regulated miR-185-5p expression. Moreover, TPD52 was confirmed as a target of miR-185-5p. Besides, PCAT6 regulated the radiosensitivity of TNBC cells through acting as a molecular sponge of miR-185-5p to modulate TPD52 expression.

Conclusion

Knockdown of PCAT6 promoted the radiosensitivity of TNBC cells through regulating miR-185-5p/TPD52 axis, providing a vital theoretical basis to improve the radiotherapy efficiency of TNBC.

LncRNA PCAT6 Accelerates the Progression and Chemoresistance of Cervical Cancer Through Up-Regulating ZEB1 by Sponging miR-543

Background

Cervical cancer (CC) is a common cancer with a poor prognosis due to the chemoresistance of CC cells to cisplatin. This study aimed to investigate the biological significance of lncRNA prostate cancer-associated transcript 6 (PCAT6) in the carcinogenesis of CC.

Materials and Methods

Quantitative real-time polymerase chain reaction (qRT-PCR) was carried out to measure the abundance of PCAT6, miR-543 and zinc finger E-box binding protein 1 (ZEB1) in CC tissues and cells. The combination between miR-543 and lncRNA PCAT6 or ZEB1 was predicted by Starbase and was verified by dual-luciferase reporter assay, RNA-pull down assay and RNA immunoprecipitation (RIP) assay. Cell proliferation and chemoresistance to cisplatin were detected by 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay. Cell apoptosis and metastasis were determined by flow cytometry, Western blot and transwell migration and invasion assays.

Results

The abundance of ZEB1 protein was measured by Western blot assay. Murine xenograft model was established to confirm the function of lncRNA PCAT6 in vivo. The abundance of lncRNA PCAT6 was enhanced in CC tissues and cells compared with that in corresponding normal tissues and normal cervical epithelial cells Ect1/E6E7. MiR-543 was a target of PCAT6 and was negatively regulated by PCAT6. PCAT6 accelerated the proliferation, metastasis and the chemoresistance of CC cells to cisplatin while suppressed the apoptosis of CC cells. The overexpression of PCAT6 reversed the inhibitory effects of miR-543 accumulation on the proliferation, metastasis and chemoresistance of CC cells to cisplatin and the promoting impact on the apoptosis of CC cells. ZEB1 was a direct target of miR-543, and it functioned as the downstream gene of PCAT6/miR-543 to exert its oncogenic role in CC. PCAT6 promoted the growth of murine xenograft tumor through miR-543/ZEB1 axis in vivo.

Conclusion

LncRNA PCAT6 facilitated the proliferation, metastasis and chemoresistance of CC cells to cisplatin while impeded the apoptosis of CC cells via PCAT6/miR-543/ZEB1 axis. PCAT6/miR-543/ZEB1 axis might be a promising target for CC therapy.

Hypothalamic miR-30 regulates puberty onset via repression of the puberty-suppressing factor, Mkrn3

Mkrn3, the maternally imprinted gene encoding the makorin RING-finger protein-3, has recently emerged as putative pubertal repressor, as evidenced by central precocity caused by MKRN3 mutations in humans; yet, the molecular underpinnings of this key regulatory action remain largely unexplored. We report herein that the microRNA, miR-30, with three binding sites in a highly conserved region of its 3' UTR, operates as repressor of Mkrn3 to control pubertal onset. Hypothalamic miR-30b expression increased, while Mkrn3 mRNA and protein content decreased, during rat postnatal maturation. Neonatal estrogen exposure, causing pubertal alterations, enhanced hypothalamic Mkrn3 and suppressed miR-30b expression in female rats. Functional in vitro analyses demonstrated a strong repressive action of miR-30b on Mkrn3 3' UTR. Moreover, central infusion during the juvenile period of target site blockers, tailored to prevent miR-30 binding to Mkrn3 3' UTR, reversed the prepubertal down-regulation of hypothalamic Mkrn3 protein and delayed female puberty. Collectively, our data unveil a novel hypothalamic miRNA pathway, involving miR-30, with a prominent role in the control of puberty via Mkrn3 repression. These findings expand our current understanding of the molecular basis of puberty and its disease states.

Long noncoding RNA PCAT6 functions as an oncogene by binding to EZH2 and suppressing LATS2 in non-small-cell lung cancer

Background

NSCLC (non-small-cell lung cancer) is the leading cause of cancer-related mortality worldwide. Both epigenetic and genetic changes contribute to the initiation, development and metastasis of NSCLC. Recently, accumulating data have begun to support the notion that long noncoding RNAs (lncRNAs) function as new crucial regulators of diverse biological processes, including proliferation, apoptosis and metastasis, and play crucial roles in tumorigenesis. Nevertheless, further study is warranted to comprehensively determine lncRNAs' functions and potential mechanism.

Methods

In this study, we performed a comprehensive analysis of the lncRNA expression profile of NSCLC using data from TCGA and Gene Expression Omnibus (GEO). PCAT6 expression level in a cohort of 60 pairs of NSCLC tissues using quantitative real-time PCR (qRT-PCR). Additionally, Loss-of-function assays and gain-of-function assays were used to assess the role of PCAT6 in promoting NSCLC progression. Tumor formation assay in a nude mouse model was performed to verity the role of PCAT6 in NSCLC in vivo. Meanwhile, RIP, ChIP, resue experiment and western blot assays were used to highlights the potential molecular mechanism of PCAT6 in NSCLC.

Findings

We identified that an oncogene, PCAT6, was upregulated in NSCLC, and this upregulation was verified in a cohort of 60 pairs of NSCLC tissues. Additionally, the expression level of PCAT6 was correlated with tumor size (P = .036), lymph node metastasis (P = .029) and TNM stage (P = .038). Loss-of-function and gain-of-function assays were used to assess the role of PCAT6 in promoting NSCLC progression. The results revealed that PCAT6 knockdown mitigated NSCLC cell growth by inducing G1-phase cell cycle arrest and apoptosis in vitro and in vivo. Whereas, PCAT6 overexpression could promoted tumor cell growth. Meanwhile, PCAT6 additionally promoted NSCLC cell migration and invasion. Furthermore, mechanistic investigation demonstrated that the oncogenic activity of PCAT6 is partially attributable to its repression of LATS2 via association with the epigenetic repressor EZH2 (Enhancer of zeste homolog 2). Overall, our study highlights the essential role of PCAT6 in NSCLC, suggesting that PCAT6 might be a potent therapeutic target for patients with NSCLC.