lncRNA SLCO4A1-AS1 promotes growth and invasion of bladder cancer through sponging miR-335-5p to upregulate OCT4

LINC00662 Promotes Aggressive Traits by Modulating OCT4 Expression through miR-335-5p in Gallbladder Cancer Cells

Long non-coding RNAs (lncRNAs) are nucleotide sequences that participate in different biological processes and are associated with different pathologies, including cancer. Long intergenic non-protein-coding RNA 662 (LINC00662) has been reported to be involved in different cancers, including colorectal, prostate, and breast cancer. However, its role in gallbladder cancer has not yet been described. In this article, we hypothesize that LINC00662 has an important role in the acquisition of aggressiveness traits such as a stem-like phenotype, invasion, and chemoresistance in gallbladder cancer. Here, we show that LINC00662 is associated with larger tumor size and lymph node metastasis in patients with gallbladder cancer. Furthermore, we show that the overexpression of LINC00662 promotes an increase in CD133+/CD44+ cell populations and the expression of stemness-associated genes. LINC00662 promotes greater invasive capacity and the expression of genes associated with epithelial-mesenchymal transition. In addition, the expression of LINC00662 promotes resistance to cisplatin and 5-fluorouracil, associated with increased expression of chemoresistance-related ATP-binding cassette (ABC) transporters in gallbladder cancer (GBC) cell lines. Finally, we show that the mechanism by which LINC00662 exerts its function is through a decrease in microRNA 335-5p (miR-335-5p) and an increase in octamer-binding transcription factor 4 (OCT4) in GBC cells. Thus, our data allow us to propose LINC00662 as a biomarker of poor prognosis and a potential therapeutic target for patients with GBC.

LncRNA RP11-93B14.5 promotes gastric cancer cell growth through PI3K/AKT signaling pathway

OBJECTIVE

Emerging evidence indicates that long non-coding RNA (lncRNA) RP11-93B14.5 facilitates tumor progression in variety of malignancies. The present study proposed to study the functional effect of lncRNA RP11-93B14.5 in gastric cancer (GC) as well as the underlying mechanism.

METHODS

Bioinformatics analysis was utilized to analyze lncRNA expression in GC tissues. siRNA was used for knockdown of RP11-93B14.5 in GC cells MKN45 and KATO III. The stable knockdown cell lines were constructed by CRISPR-Cas9. Cell counting kit-8 (CCK-8) assay and soft agar colony formation assay were used to analyze GC cell viability. Flow cytometry analysis was performed to analyze the cell cycle distribution of MKN45 and KATO III. RNA sequencing (RNA-seq) was employed to detect differential genes after transfection with siRP11-93B14.5. Quantitative PCR (Q-PCR) was used to examine gene expression in GC cell lines. Western-blot assay was used to measure protein levels. RNA fluorescent in situ hybridization (FISH) was conducted for lncRNA cellular location and expression.

RESULTS

Based on the Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) database, RP11-93B14.5 was upregulated in GC tissue, which was also verified in GC cell lines in comparison to the normal gastric epithelial HFE145 cells. Knockdown of RP11-93B14.5 decreased cell viability and the colony number of MKN45 and KATO III cells, and altered cell cycle distribution in vitro. RNA-seq analysis revealed RP11-93B14.5 may modulate genes expression of S100A2 and TIMP2 in MKN45 and KATO III cells. Mechanistically, RP11-93B14.5 may drive the progression of GC via S100A2 related-PI3K/AKT signaling pathway.

CONCLUSIONS

LncRNA RP11-93B14.5 knockdown alleviated the malignant phenotypes of GC cells through regulating PI3K/AKT. Our results provide evidence for the role of lncRNAs in regulating tumor progression.

SLCO4A1-AS1 regulates laryngeal squamous cell carcinoma cell phenotypes via the Wnt pathway

AIM

Long non-coding RNAs were widely reported to regulate laryngeal squamous cell carcinoma (LSCC), a prevalent tumor in the head and neck. We aimed to investigate the role of solute carrier organic anion transporter family member 4A1 antisense RNA 1 (SLCO4A1-AS1) in LSCC.

MATERIALS & METHODS

CCK-8 and colony formation assays were conducted to examine the viability and proliferation of LSCC cells. The apoptosis of LSCC cells was evaluated using flow cytometry and TUNEL assays. The distribution of SLCO4A1-AS1 in LSCC cells was detected by subcellular fractionation assay. The interaction between molecules was confirmed using luciferase reporter assay.

RESULTS

SLCO4A1-AS1 was overexpressed in LSCC tissues and cells. Furthermore, silenced SLCO4A1-AS1 repressed the proliferation and facilitated apoptosis of LSCC cells. Mechanistical investigation revealed that SLCO4A1-AS1 was a competing endogenous RNA (ceRNA) to upregulate SETD7 by binding with miR-7855-p. Additionally, SLCO4A1-AS1 positively regulated the Wnt/β-catenin signaling pathway by upregulating SETD7. Rescue experiments demonstrated that SLCO4A1-AS1 promoted LSCC proliferation and inhibited LSCC apoptosis by upregulation of SETD7 and activation of the Wnt/β-catenin pathway.

CONCLUSION

SLCO4A1-AS1 promotes proliferation and inhibits apoptosis of LSCC cells by upregulation of SETD7 in a miR-7855-5p dependent way to activate the Wnt/β-catenin pathway.

lncRNA-mediated ceRNA network in bladder cancer

Bladder cancer is a common disease associated with high rates of morbidity and mortality. Although immunotherapy approaches such as adoptive T-cell therapy and immune checkpoint blockade have been investigated for the treatment of bladder cancer, their off-target effects and ability to affect only single targets have led to clinical outcomes that are far from satisfactory. Therefore, it is important to identify novel targets that can effectively control tumor growth and metastasis. It is well known that long noncoding RNAs (lncRNAs) are powerful regulators of gene expression. Increasing evidence has shown that dysregulated lncRNAs in bladder cancer are involved in cancer cell proliferation, migration, invasion, apoptosis, and epithelial-mesenchymal transition (EMT). In this review, we focus on the roles and underlying mechanisms of lncRNA-mediated competing endogenous RNA (ceRNA) networks in the regulation of bladder cancer progression. In addition, we discuss the potential of targeting lncRNA-mediated ceRNA networks to overcome cancer treatment resistance and its association with clinicopathological features and outcomes in bladder cancer patients. We hope this review will stimulate research to develop more effective therapeutic approaches for bladder cancer treatment.

The roles of long noncoding RNAs in the regulation of OCT4 expression

OCT4 is a major transcription factor that maintains the pluripotency of stem cells, including embryonic stem cells, induced pluripotent stem cells and cancer stem cells. An increasing number of long noncoding RNAs have been reported to participate in the regulation of OCT4 expression through various mechanisms, including binding with the OCT4 gene promoter to regulate local methylation; promoting chromosomal spatial folding to form an inner ring, thereby aggregating OCT4 cis-acting elements scattered in discontinuous sites of the chromosome; competitively binding microRNAs with OCT4 to upregulate OCT4 expression at the posttranscriptional level; and sharing a promoter with OCT4. Moreover, the transcription of some long noncoding RNAs is regulated by OCT4, and certain long noncoding RNAs form feedback regulatory loops with OCT4. In this review, we summarized the research progress of the long noncoding RNAs involved in the regulation of OCT4 expression.

SLCO4A1-AS1 mediates pancreatic cancer development via miR-4673/KIF21B axis

In this study, we intended to figure out the biological significance of long non-coding RNAs (lncRNAs) solute carrier organic anion transporter family member 4A1 antisense RNA 1 (SLCO4A1-AS1) in pancreatic cancer (PC). Cell counting kit-8, colony formation, wound healing, transwell, and flow cytometry experiments were performed to reveal how SLCO4A1-AS1 influences PC cell proliferation, migration, invasion, and apoptosis. Thereafter, bioinformatics analysis, RNA immunoprecipitation assay, luciferase reporter assay, and RNA pull-down assay were applied for determining the binding sites and binding capacities between SLCO4A1-AS1 and miR-4673 or kinesin family member 21B (KIF21B) and miR-4673. The results depicted that SLCO4A1-AS1 was upregulated in PC, and SLCO4A1-AS1 knockdown suppressed PC cell growth, migration, invasion, and induced cell apoptosis. Furthermore, SLCO4A1-AS1 was verified to modulate the expression of KIF21B by binding with miR-4673. SLCO4A1-AS1 exerted an oncogenic function in PC. The overexpression of SLCO4A1-AS1 aggravated the malignant behaviors of PC via the upregulation of KIF21B by sponging miR-4673. Our findings revealed a novel molecular mechanism mediated by SLCO4A1-AS1, which might play a significant role in modulating the biological processes of PC.

Kawasaki disease: lncRNA Slco4a1 regulates the progression of human umbilical vein endothelial cells by targeting the miR-335-5p/POU5F1 axis

BACKGROUND

Kawasaki disease (KD) is an autoimmune disease with systemic vasculitis as the main pathological change, and is most common in children under 5. The role of long non-coding RNAs (lncRNAs) in human diseases has been highlighted. LncRNA Slco4a1 was reported to promote cell growth and act as an oncogenic regulator in cancer. However, the role of lncRNA Slco4a1 in KD remains unclear. This study aimed to investigate the role and mechanism of lncRNA Slco4a1 in KD.

METHODS

Enzyme linked immunosorbent assay (ELISA), qRT-PCR, Western blot, and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling (TUNEL) staining were conducted to explore the function of lncRNA Slco4a1. The interaction between POU5F1 and miR-335-5p was analyzed by the RIP assay and dual luciferase assay.

RESULTS

LncRNA Slco4a1 was significantly upregulated in the serum of KD patients compared with healthy controls. LncRNA Slco4a1 was upregulated in human umbilical vein endothelial cells (HUVECs) stimulated with KD serum. LncRNA Slco4a1 overexpression could promote the expression of inflammatory factors and apoptosis in HUVECs. The number of inflammatory cells and the infiltration area of the coronary artery in KD rats were decreased after lncRNA Slco4a1 silencing. Furthermore, lncRNA Slco4a1 is a sponge of miR-335-5p and negatively regulated the expression of miR-335-5p. POU5F1 was the downstream target of miR-335-5p, and miR-335-5p overexpression could upregulate the expression of POU5F1. Additionally, miR-335-5p overexpression could inhibit the expression of inflammatory factors and apoptosis in HUVECs. We further investigated the effect of lncRNA Slco4a1 on the mitogen-activated protein kinase (MAPK) signaling pathway, and the results showed that lncRNA Slco4a1 could promote the activation of the MAPK signaling pathway.

CONCLUSIONS

Together, these results indicated that lncRNA Slco4a1 could regulate the progression of HUVECs in KD by targeting the miR-335-5p/POU5F1 axis, providing new insights for KD treatment.

SLCO4A1-AS1 promotes colorectal tumourigenesis by regulating Cdk2/c-Myc signalling

BACKGROUND

SLCO4A1-AS1 was found to be upregulated in several cancer types, including colorectal cancer (CRC). However, the detailed roles of SLCO4A1-AS1 in CRC remain to be elucidated. Therefore, we investigated the functions, mechanism, and clinical significance of SLCO4A1-AS1 in colorectal tumourigenesis.

METHODS

We measured the expression of SLCO4A1-AS1 in CRC tissues using qRT-PCR and determined its correlation with patient prognosis. Promoter methylation analyses were used to assess the methylation status of SLCO4A1-AS1. Gain- and loss-of-function assays were used to evaluate the effects of SLCO4A1-AS1 on CRC growth in vitro and in vivo. RNA pull-down, RNA immunoprecipitation, RNA-seq, luciferase reporter and immunohistochemistry assays were performed to identify the molecular mechanism of SLCO4A1-AS1 in CRC.

RESULTS

SLCO4A1-AS1 was frequently upregulated in CRC tissues based on multiple CRC cohorts and was associated with poor prognoses. Aberrant overexpression of SLCO4A1-AS1 in CRC is partly attributed to the DNA hypomethylation of its promoter. Ectopic SLCO4A1-AS1 expression promoted CRC cell growth, whereas SLCO4A1-AS1 knockdown repressed CRC proliferation both in vitro and in vivo. Mechanistic investigations revealed that SLCO4A1-AS1 functions as a molecular scaffold to strengthen the interaction between Hsp90 and Cdk2, promoting the protein stability of Cdk2. The SLCO4A1-AS1-induced increase in Cdk2 levels activates the c-Myc signalling pathway by promoting the phosphorylation of c-Myc at Ser62, resulting in increased tumour growth.

CONCLUSIONS

Our data demonstrate that SLCO4A1-AS1 acts as an oncogene in CRC by regulating the Hsp90/Cdk2/c-Myc axis, supporting SLCO4A1-AS1 as a potential therapeutic target and prognostic factor for CRC.

ceRNA Network of lncRNA/miRNA as Circulating Prognostic Biomarkers in Non-Hodgkin Lymphomas: Bioinformatic Analysis and Assessment of Their Prognostic Value in an NHL Cohort

Research has been focusing on identifying novel biomarkers to better stratify non-Hodgkin lymphoma patients based on prognosis. Studies have demonstrated that lncRNAs act as miRNA sponges, creating ceRNA networks to regulate mRNA expression, and its deregulation is associated with lymphoma development. This study aimed to identify novel circulating prognostic biomarkers based on miRNA/lncRNA-associated ceRNA network for NHL. Herein, bioinformatic analysis was performed to construct ceRNA networks for hsa-miR-150-5p and hsa-miR335-5p. Then, the prognostic value of the miRNA–lncRNA pairs’ plasma levels was assessed in a cohort of 113 NHL patients. Bioinformatic analysis identified MALAT1 and NEAT1 as hsa-miR-150-5p and has-miR-335-5p sponges, respectively. Plasma hsa-miR-150-5p/MALAT1 and hsa-miR335-5p/NEAT1 levels were significantly associated with more aggressive and advanced disease. The overall survival and progression-free survival analysis indicated that hsa-miR-150-5p/MALAT1 and hsa-miR335-5p/NEAT1 pairs’ plasma levels were remarkably associated with NHL patients’ prognosis, being independent prognostic factors in a multivariate Cox analysis. Low levels of hsa-miR-150-5p and hsa-miR-335-5p combined with high levels of the respective lncRNA pair were associated with poor prognosis of NHL patients. Overall, the analysis of ceRNA network expression levels may be a useful prognostic biomarker for NHL patients and could identify patients who could benefit from more intensive treatments.

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.

Linc-ROR has a Potential ceRNA Activity for OCT4A by Sequestering miR-335-5p in the HEK293T Cell Line

Linc-ROR has a regulatory role in reprogramming, and the core stem cell transcription factors, OCT4, SOX2, and NANOG, regulate its expression. MicroRNAs (miRNAs) are also a critical constituent of pivotal posttranscriptional regulatory pathways. One of such interactions is a competing endogenous RNA interaction that connects small and long non-coding RNAs with coding transcripts. Here, we aimed to investigate the existence of such associations between OCT4A, Linc-ROR, hsa-miR-335-5p, and hsa-miR-544. Bioinformatic analysis was performed to evaluate the expression status of OCT4A, Linc-ROR, miR-335, and miR-544 throughout differentiation as well as in various differentiated cells. The complete lengths of OCT4A and Linc-ROR, and OCT4A 3'-UTR were cloned in the luciferase reporter vector, and the precursors of miR-335 and miR-544 were cloned in expression vectors. Following the overexpression of miR-335 and miR-544 in the 5637 cell line, the endogenous expression of OCT4A and Linc-ROR was evaluated. Afterward, the expression vectors of miRNAs and the reporter vectors of OCT4A/Linc-ROR were co-transfected in the HEK293T cell line. Via the Dual-Luciferase assay, the effect of the overexpression of miRNAs on their two possible targets (Linc-ROR and OCT4A) was investigated. The bioinformatic analysis demonstrated a relatively similar expression pattern for OCT4A and Linc-ROR, while miR-335 showed a different expression status. Both miR-335 and miR-544 inhibited the endogenous expression of OCT4A. The Dual-Luciferase assay likewise confirmed the inhibitory effect of miR-335 and miR-544 on OCT4A expression. In contrast, the miR-335 inhibitory effect was reversed in the presence of Linc-ROR, resulting in the upregulation of OCT4A. Such evidence suggests that Linc-ROR may compete with OCT4A to interact with miR-335.

Biological functions and clinical significance of long noncoding RNAs in bladder cancer

Bladder cancer (BCa) is one of the 10 most common cancers with high morbidity and mortality worldwide. Long noncoding RNAs (lncRNAs), a large class of noncoding RNA transcripts, consist of more than 200 nucleotides and play a significant role in the regulation of molecular interactions and cellular pathways during the occurrence and development of various cancers. In recent years, with the rapid advancement of high-throughput gene sequencing technology, several differentially expressed lncRNAs have been discovered in BCa, and their functions have been proven to have an impact on BCa development, such as cell growth and proliferation, metastasis, epithelial-mesenchymal transition (EMT), angiogenesis, and drug-resistance. Furthermore, evidence suggests that lncRNAs are significantly associated with BCa patients' clinicopathological characteristics, especially tumor grade, TNM stage, and clinical progression stage. In addition, lncRNAs have the potential to more accurately predict BCa patient prognosis, suggesting their potential as diagnostic and prognostic biomarkers for BCa patients in the future. In this review, we briefly summarize and discuss recent research progress on BCa-associated lncRNAs, while focusing on their biological functions and mechanisms, clinical significance, and targeted therapy in BCa oncogenesis and malignant progression.

LncRNA SLCO4A1-AS1 Accelerates Growth and Metastasis of Gastric Cancer via Regulation of the miR-149/XIAP Axis

OBJECTIVE

Recently, long noncoding RNA SLCO4A1 antisense RNA 1 (SLCO4A1-AS1) has been shown to act as an oncogene in several cancer types; however, its role in gastric cancer (GC) and its underlying molecular mechanisms are yet to be elucidated.

METHODS

Using the ENCORI database, we identified SLCO4A1-AS1, miR-149-5p (miR-149), and the X-linked inhibitor of apoptosis (XIAP) whose expressions were obviously changed in GC samples, and analyzed the correlation between their expressions in GC samples. Moreover, we explored the expression of SLCO4A1-AS1, miR-149, and XIAP in clinical samples and GC cell lines using RT-qPCR and western blotting assay; the correlation between them was analyzed using RNA immunoprecipitation and dual-luciferase reporter. CCK-8, colony formation, and Transwell assays were conducted to determine the effects of SLCO4A1-AS1, miR-149, and XIAP expression on cell proliferation, migration, and invasion, respectively. A nude mouse xenograft model was used to explore their function in xenograft growth.

RESULTS

SLCO4A1-AS1 was significantly upregulated in the GC samples and cell lines, and a high level of SLCO4A1-AS1 was associated with an advanced tumor stage and shortened patient survival. Mechanistically, SLCO4A1-AS1 post-transcriptionally regulated XIAP by functioning as competing endogenous RNA in GC to sponge miR-149. Further functional assays revealed that the overexpression of miR-149 and knockdown of XIAP considerably inhibited GC cell viability and its migratory and invasive characteristics in vitro. SLCO4A1-AS1 knockdown also determined the function of GC cells but was diminished by the miR-149 inhibitor in vitro. Finally, we demonstrated that the deletion of SLCO4A1-AS1 suppressed tumor growth and metastasis in vivo.

CONCLUSIONS

Altogether, these findings suggest that SLCO4A1-AS1 functions as a crucial oncogenic lncRNA in GC and it can facilitate GC tumor growth and metastasis by interacting with miR-149 and enhancing XIAP expression. Therefore, SLCO4A1-AS1 is a potential novel therapeutic target in GC treatment.

Ferroptosis-related lncRNA pairs to predict the clinical outcome and molecular characteristics of pancreatic ductal adenocarcinoma

Ferroptosis is a form of regulated cell death initiated by oxidative perturbations that can be blocked by iron chelators and lipophilic antioxidants, and ferroptosis may be the silver bullet treatment for multiple cancers, including immunotherapy- and chemotherapy-insensitive cancers such as pancreatic ductal adenocarcinoma (PDAC). Numerous studies have noted that long non-coding RNAs (lncRNAs) regulate the biological behaviour of cancer cells by binding to DNA, RNA and protein. However, few studies have reported the role of lncRNAs in ferroptosis processes and the function of ferroptosis-associated lncRNAs. The primary objective of the present study was to identify ferroptosis-related lncRNAs using bioinformatic approaches combined with experimental validation. The second objective was to construct a prognostic model to predict the overall survival of patients with PDAC. The present study identified ferroptosis-related lncRNAs using a bioinformatic approach and validated them in an independent pancreatic cancer cohort from Fudan University Shanghai Cancer Center. The lncRNA SLCO4A1-AS1 was identified as a novel molecule mediating ferroptosis resistance in vitro. A novel algorithm was used to construct a '0 or 1' matrix-based prognosis model, which showed promising diagnostic accuracy for potential clinical translation (area under the curve = 0.89 for the 2-year survival rate). Notably, molecular subtypes classified by the risk scores of the model did not belong to any previously reported subtypes of PDAC. The immune microenvironment, metabolic activities, mutation landscape and ferroptosis sensitivity were significantly distinct between patients with different risk scores. Sensitivity (IC50) to 30 common anticancer drugs was analysed between patients with different risks, and imatinib and axitinib were found to be potential drugs for the treatment of patients with lower risk scores. Overall, we developed an accurate prognostic model based on the expression patterns of ferroptosis lncRNAs, which may contribute greatly to the evaluation of patient prognosis, molecular characteristics and treatment modalities and could be further translated into clinical applications.

Long non-coding RNAs as new players in bladder cancer: Lessons from pre-clinical and clinical studies

The clinical management of bladder cancer (BC) has become an increasing challenge due to high incidence rate of BC, malignant behavior of cancer cells and drug resistance. The non-coding RNAs are considered as key factors involved in BC progression. The long non-coding RNAs (lncRNAs) are RNA molecules and do not encode proteins. They have more than 200 nucleotides in length and affect gene expression at epigenetic, transcriptional and post-transcriptional phases. The lncRNAs demonstrate abnormal expression in BC cells and tissues. The present aims to identifying lncRNAs with tumor-suppressor and tumor-promoting roles, and evaluating their roles as regulatory of growth and migration. Apoptosis, glycolysis and EMT are tightly regulated by lncRNAs in BC. Response of BC cells to cisplatin, doxorubicin and gemcitabine chemotherapy is modulated by lncRNAs. LncRNAs regulate immune cell infiltration in tumor microenvironment and affect response of BC cells to immunotherapy. Besides, lncRNAs are able to regulate microRNAs, STAT3, Wnt, PTEN and PI3K/Akt pathways in affecting both proliferation and migration of BC cells. Noteworthy, anti-tumor compounds and genetic tools such as siRNA, shRNA and CRISPR/Cas systems can regulate lncRNA expression in BC. Finally, lncRNAs and exosomal lncRNAs can be considered as potential diagnostic and prognostic tools in BC.

Role of Long Non-coding RNAs on Bladder Cancer

Bladder cancer (BC) is the most common malignant tumor in the urinary system, and its early diagnosis is conducive to improving clinical prognosis and prolonging overall survival time. However, few biomarkers with high sensitivity and specificity are used as diagnostic markers for BC. Multiple long non-coding RNAs (lncRNAs) are abnormally expressed in BC, and play key roles in tumorigenesis, progression and prognosis of BC. In this review, we summarize the expression, function, molecular mechanisms and the clinical significance of lncRNAs on bladder cancer. There are more than 100 dysregulated lncRNAs in BC, which are involved in the regulation of proliferation, cell cycle, apoptosis, migration, invasion, metabolism and drug resistance of BC. Meanwhile, the molecular mechanisms of lncRNAs in BC was explored, including lncRNAs interacting with DNA, RNA and proteins. Additionally, the abnormal expression of thirty-six lncRNAs is closely associated with multiple clinical characteristics of BC, including tumor size, metastasis, invasion, and drug sensitivity or resistance of BC. Furthermore, we summarize some potential diagnostic and prognostic biomarkers of lncRNA for BC. This review provides promising novel biomarkers in early diagnosis, prognosis and monitoring of BC based on lncRNAs.

LncRNA SLCO4A1-AS1 modulates colon cancer stem cell properties by binding to miR-150-3p and positively regulating SLCO4A1

Long non-coding RNAs (lncRNAs) play important roles in a range of different human cancers. However, the role of lncRNA solute carrier organic anion transporter family member 4A1-AS1 (SLCO4A1-AS1) in colon cancer remains enigmatic. Hence, we aimed to explore the specific role of SLCO4A1-AS1 in colon cancer stem cells. Colon cancer-related differentially expressed lncRNA and mRNA were screened using microarray-based analysis, and the expression of SLCO4A1-AS1 and SLCO4A1 in colon cancer tissues was determined using reverse transcription quantitative polymerase chain reaction and western blot analysis. The interaction among SLCO4A1-AS1, microRNA-150-3p (miR-150-3p) and SLCO4A1 was verified using dual-luciferase reporter assay, RNA immunoprecipitation and RNA pull-down. Moreover, SLCO4A1-AS1, miR-150-3p and/or SLCO4A1 were overexpressed or depleted in colon cancer cells to detect their effects on migration, invasion, sphere formation, apoptosis and tumorigenesis abilities of colon cancer stem CD133+CD44+ cells using both in vitro and in vivo assays. SLCO4A1-AS1 and SLCO4A1 were screened as the differentially expressed lncRNA and mRNA in colon cancer tissues. SLCO4A1-AS1 was confirmed to competitively bind to miR-150-3p to elevate SLCO4A1 expression. Moreover, knockdown of SLCO4A1-AS1 decreased SLCO4A1 expression, thus inhibiting cell migration, invasion, sphere formation, and tumorigenesis abilities and enhancing the apoptosis of CD133+CD44+ cells. Collectively, these findings provide evidence demonstrating that depleting SLCO4A1-AS1 competitively binds to miR-150-3p, which downregulates SLCO4A1 expression, thus hindering colon cancer progression.

Functions and Targets of miR-335 in Cancer

MicroRNAs (miRNAs) are small non-coding RNAs (18~25 nt in length) that act as master regulators of eukaryotic gene expression. They might play an oncogenic or tumor-suppressive role in multiple cancers. In recent decades, several studies have focused on the functions and mechanisms of miR-335 in cancer. The expression level of miR-335 in tissues and cells varies with cancer types, and miR-335 has been proposed as a potential biomarker for the prognosis of cancer. Besides, miR-335 may serve as an oncogene or tumor suppressor via regulating different targets or pathways in tumor initiation, development, and metastasis. Furthermore, miR-335 also influences tumor microenvironment and drug sensitivity. MiR-335 is regulated by various factors such as lncRNAs and microRNAs. In this review, we reveal the functions and targets of miR-335 in various cancers and its potential application as a possible biomarker in prognostic judgment and treatment of malignant tumors.

OCT3/4 enhances tumor immune response by upregulating the TET1-dependent NRF2/MDM2 axis in bladder cancer

This study aimed to investigate the function of OCT3/4 on tumor immune escape in bladder cancer. Initially, the expression of OCT3/4, TET1, NRF2 and MDM2 was quantified in tumor tissues and cells, followed by gain- or loss-of-function studies to define their roles in cell migration, invasion and apoptosis and tumorigenicity in nude mice. Bladder cancer presented with abundant expression levels of OCT3/4, TET1, NRF2 and MDM2. We found that OCT3/4 promoted TET1 expression via binding to its promoter and that TET1 recruited MLL protein to NRF2 promoter and upregulated its expression, while NRF2 enhanced MDM2 expression. Upregulated MDM2 accelerated tumor immune escape in bladder cancer in mice. OCT3/4 knockdown suppressed the cell migration and invasion while inducing apoptosis, and consequently prevented tumor growth and immune escape in mice. Collectively, OCT3/4 may promote the progression of tumor immune escape in bladder cancer through acting as a promoter of the TET1/NRF2/MDM2 axis.

Construction of a long noncoding RNA-based competing endogenous RNA network and prognostic signatures of left- and right-side colon cancer

Background

Cancers located on the right and left sides of the colon have distinct clinical and molecular characteristics. This study aimed to explore the regulatory mechanisms of location-specific long noncoding RNAs (lncRNAs) as competing endogenous RNAs (ceRNAs) in colon cancer and identify potential prognostic biomarkers.

Method

Differentially expressed lncRNAs (DELs), miRNAs (DEMs), and genes (DEGs) between right- and left-side colon cancers were identified by comparing RNA sequencing profiles. Functional enrichment analysis was performed for the DEGs, and a ceRNA network was constructed. Associations between DELs and patient survival were examined, and a DEL-based signature was constructed to examine the prognostic value of these differences. Clinical colon cancer tissues and Gene Expression Omnibus (GEO) datasets were used to validate the results.

Results

We identified 376 DELs, 35 DEMs, and 805 DEGs between right- and left-side colon cancers. The functional enrichment analysis revealed the functions and pathway involvement of DEGs. A ceRNA network was constructed based on 95 DEL–DEM–DEG interactions. Three DELs (LINC01555, AC015712, and FZD10-AS1) were associated with the overall survival of patients with colon cancer, and a prognostic signature was established based on these three DELs. High risk scores for this signature indicated poor survival, suggesting that the signature has prognostic value for colon cancer. Examination of clinical colon cancer tissues and GEO dataset analysis confirmed the results.

Conclusion

The ceRNA regulatory network suggests roles for location-specific lncRNAs in colon cancer and allowed the development of an lncRNA-based prognostic signature, which could be used to assess prognosis and determine treatment strategies in patients with colon cancer.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01901-3.

LncRNA SNHG8 Promotes Proliferation and Inhibits Apoptosis of Diffuse Large B-Cell Lymphoma via Sponging miR-335-5p

Long-chain non-coding RNAs (LncRNAs) are expressed in diffuse large B-cell lymphoma (DLBCL) tissues and have played a regulatory role in DLBCL with a cancer-promoting effect. In this study, the role of LncRNA SNHG8 in the regulation of DLBCL cells is investigated, and its underlying mechanism is explored. The database of the Gene Expression Profiling Interactive Analysis (GEPIA) was searched, and the expression of SNHG8 in DLBCL and normal tissues was examined. The expression of SNHG8 was evaluated in several DLBCL cell lines and a normal lymphocyte cell line. It was found that SNHG8 was overexpressed in DLBCL tissues and cells in comparison with their normal counterparts. The short hairpin RNA (shRNA) plasmids of SNHG8 were transfected into DLBCL cells to knockdown the expression of SNHG8, followed by assays of proliferation, colony formation, apoptosis, and related protein expression. The results showed that the knockdown of SNHG8 significantly inhibited DLBCL cell proliferation and colony formation while promoting cell apoptosis. Moreover, the knockdown of SNHG8 reduced the expression of Ki-67, proliferating cell nuclear antigen (PCNA), and Bcl-2 and enhanced the expression of Bax and cleaved caspase 3/9. MiR-335-5p was predicted to be a potential target of SNHG8 by using the bioinformatics analysis, and the interaction between the two was validated by using the dual luciferase assay. In addition, the knockdown of SNHG8 increased the level of miR-335-5p, whereas miR-335-5p mimic decreased the expression of SNHG8. Finally, U2932 cells were co-transfected with or without sh-SNHG8 and miR-335-5p inhibitors, whose proliferation, colony formation, and apoptosis were determined subsequently. It was demonstrated that the presence of an miR-335-5p inhibitor partially canceled the inhibitory effects of the knockdown of SNHG8 on DLBCL cell proliferation and colony formation and the stimulating effects of the knockdown of SNHG8 on cell apoptosis. Taken together, our study suggests that lncRNA SNHG8 exerts a cancer-promoting effect on DLBCL via targeting miR-335-5p.

The lncRNA SLCO4A1-AS1/miR-876-3p/RBBP6 axis regulates cell proliferation and apoptosis in acute lymphocytic leukemia via the JNK signaling pathway

INTRODUCTION

Acute lymphocytic leukemia (ALL) is a hematologic malignancy caused by the clonal proliferation of immature lymphocytes. Long noncoding RNAs (lncRNAs) have been reported as critical regulators in several cancers, including ALL. LncRNA SLCO4A1 antisense RNA 1 (SLCO4A1-AS1) has been revealed to be implicated in tumorigenesis of several cancers. Our study focused on the role of SLCO4A1-AS1 in ALL.

METHODS

RT-qPCR, Western blot analysis, CCK-8, EdU, and Flow cytometry analysis were used to explore the biological function of SLCO4A1-AS1 in ALL cellular processes. Luciferase reporter and RNA pull-down assays were applied to explore the mechanism of SLCO4A1-AS1 in ALL cells.

RESULTS

SLCO4A1-AS1 was upregulated in ALL tissues and cell lines. We found that suppression of SLCO4A1-AS1 suppressed ALL cell proliferation and facilitated cell apoptosis. Our result confirmed that SLCO4A1-AS1 acted as a ceRNA by sponging microRNA 876-3p (miR-876-3p) to upregulate retinoblastoma binding protein 6 (RBBP6) expression in ALL cells. Moreover, SLCO4A1-AS1 activated the JNK signaling pathway by upregulating RBBP6. Rescue assays revealed that the activation of the JNK signaling or overexpression of RBBP6 revered the suppressive effect of SLCO4A1-AS1 knockdown on growth of ALL cells.

CONCLUSION

SLCO4A1-AS1 promoted cell growth of ALL by the miR-876-3p/RBBP6 axis to activate the JNK signaling pathway.

Exosome-transmitted miRNA-335-5p promotes colorectal cancer invasion and metastasis by facilitating EMT via targeting RASA1

Exosomal microRNA (miRNA) secretion has been characterized as a vital factor in intercellular communication among cancer cells. However, little is known about cancer-secreted miRNAs specifically involved in metastasis of colorectal cancer (CRC). Here, we found that exosomes derived from metastatic CRC cell line SW620 promoted migration, invasion, and epithelial-mesenchymal transition (EMT) of CRC cells. The profiling of exosome miRNAs revealed that microRNA (miR)-335-5p was highly expressed in exosomes from metastatic SW620 cells compared to those derived from primary SW480 cells. miR-335-5p was transmitted from metastatic SW620 cells to CRC cells via exosomes and promoted migration, invasion, and EMT of CRC cells. Moreover, exosome-transmitted miRNA-335-5p promotes CRC cell invasion and metastasis by facilitating EMT via targeting RAS p21 protein activator 1 (RASA1). Overexpression of RASA1 abolished the promotive effects of exosomal miR-335-5p on CRC cell migration, invasion, and EMT. Collectively, our data revealed that exosomal miR-335-5p derived from metastatic CRC cells promotes CRC cell invasion and metastasis by facilitating EMT via targeting RASA1, which may serve as a potential therapeutic target for CRC metastasis.

Overexpression of DDR1 Promotes Migration, Invasion, Though EMT-Related Molecule Expression and COL4A1/DDR1/MMP-2 Signaling Axis

Purpose:

Discoidin domain receptor 1 (DDR1) belongs to a novel class of receptor tyrosine kinases. Previous evidence indicates that DDR1 overexpression promotes the aggressive growth of bladder cancer (BC) cells. This study aimed to investigate the molecular mechanisms by which DDR1 influences BC.

Methods:

DDR1 was transfected into human BC RT4 cells. DDR1, COL4A1, and MMP-2 expression in 30 BC tissues and paired adjacent tissues were examined by real-time polymerase chain reaction (RT-PCR) and immunohistochemistry. Transwell assays were conducted to determine cell migration and invasion. RT-PCR and western blot (WB) were also used to measure the DDR1, COL4A1, MMP-2, and EMT-related gene (ZEB1 and SLUG) expression in RT4 cells after DDR1 overexpression.

Results:

COL4A1 and MMP-2 interacted with DDR1 in the PPI network. RT-PCR and immunohistochemistry results showed that both mRNA and protein levels of DDR1 and COL4A1 were significantly increased in BC tissue, while the expression of MMP-2 was increased only at the mRNA level (P < 0.05). Overexpression of DDR1 in RT4 cells significantly promoted their migratory and invasive capabilities in vitro (P < 0.05). Moreover, overexpression of DDR1 in RT4 cells increased the mRNA and protein expression of ZEB1, SLUG, COL4A1, and MMP-2 (P < 0.01). DDR1-mediated migration and invasion of RT4 cells were reversed after COL4A1-siRNA treatment.

Conclusion:

DDR1 may be a potential therapeutic target in BC patients.

Platycodin D (PD) regulates LncRNA-XIST/miR-335 axis to slow down bladder cancer progression in vitro and in vivo

Recently, increasing evidences indicated that Platycodin D (PD) served as an effective anti-tumor drug for cancer treatment in clinic. However, the molecular mechanisms are still unclear. In the present study, we proved that PD regulated LncRNA-XIST/miR-335 axis to hamper the development of bladder cancer in vitro and in vivo. Mechanistically, PD inhibited malignant phenotypes, including cell proliferation, invasion, migration and epithelial-mesenchymal transition (EMT), and promoted cell apoptosis in bladder cancer cells in a time- and dose-dependent manner. In addition, the following experiments validated that PD inhibited LncRNA-XIST expressions, while increased miR-335 expression levels in bladder cancer cells. Next, by conducting the dual-luciferase reporter gene system assay and RNA pull-down assay, we validated that LncRNA-XIST inhibited miR-335 expressions through acting as RNA sponges, and the promoting effects of PD stimulation on miR-335 levels were abrogated by upregulating LncRNA-XIST. Interestingly, both silencing LncRNA-XIST and miR-335 overexpression enhanced the inhibiting effects of PD on the malignant phenotypes in bladder cancer cells. Consistently, the xenograft tumor-bearing mice models were established, and the data indicated that PD slowed down tumor growth and inhibited tumorigenesis in vivo, which were also aggravated by downregulating LncRNA-XIST. In general, analysis of data proved that targeting LncRNA-XIST/miR-335 axis was novel to enhance the anti-tumor effects of PD in bladder cancer in vitro and in vivo, and this study provided alternative therapeutic strategies for bladder cancer treatment in clinic.

SLCO4A1-AS1 promotes cell growth and induces resistance in lung adenocarcinoma by modulating miR-4701-5p/NFE2L1 axis to activate WNT pathway

Long noncoding RNAs (lncRNAs) possessed essential functions in the biological behaviors of various human cancers. SLCO4A1 antisense RNA 1 (SLCO4A1-AS1) is a lncRNA that has been reported as a oncogenic regulator in colorectal cancer and bladder cancer. However, whether it exerted functions in the gene expression and cellular processes in lung adenocarcinoma (LUAD) remains still obscure. In the present research, we unveiled the high level of SLCO4A1-AS1 in LUAD tissues and cells. Moreover, functional assays indicated that SLCO4A-AS1 facilitated LUAD cell proliferation, motility, and cisplatin-resistance. Besides, mechanism investigation revealed that miR-4701-5p could interact with SLCO4A1-AS1 and directly target to NFE2L1. The expression correlation between miR-4701-5p and SLCO4A1-AS1 or NFE2L1 was found to be negative. Moreover, NFE2L1 was expressed at a same tendency with SLCO4A1-AS1 in LUAD tissues and cells. In addition, it was confirmed that NFE2L1 was involved in SLCO4A1-AS1-mediated activation of WNT pathway. According to rescue assays, NFE2L1 could involve in SLCO4A1-AS1-mediated LUAD cell growth. Conclusively, our study demonstrated that SLCO4A1-AS1 facilitated cell growth and enhanced the resistance of LUAD cells to chemotherapy via activating WNT pathway through miR-4701-5p/NFE2L1 axis.

Long non-coding RNA SLCO4A1-AS1 drives the progression of non-small-cell lung cancer by modulating miR-223-3p/IKKα/NF-κB signaling

Globally, lung cancer is known as a major cause of cancer-associated death and non-small-cell lung cancer (NSCLC) accounts for majority of all cases. Growing evidence has emerged that long non-coding RNAs (lncRNAs) act as vital regulatory molecules in various malignancies. Nevertheless, the function of SLCO4A1 antisense RNA 1(SLCO4A1-AS1) in NSCLC is vague. This study intended to investigate the biological role and probable regulatory mechanism of SLCO4A1-AS1 in NSCLC. qRT-PCR revealed that SLCO4A1-AS1 level was upregulated in NSCLC. Function assays manifested that silence of SLCO4A1-AS1 attenuated NSCLC cell proliferation, migration and invasion but promoted NSCLC cell apoptosis. Furthermore, we disclosed that SLCO4A1-AS1 activated NF-κB pathway in NSCLC, and that IKKα, an NF-κB pathway-related gene, possessed an enhanced level in NSCLC tissues and cells. Importantly, miR-223-3p bound with SLCO4A1-AS1 and IKKα. Further, SLCO4A1-AS1 competitively bound with miR-223-3p to increase IKKα expression, thereby activating NF-κB signaling pathway. In conclusion, SLCO4A1-AS1 drove NSCLC progression by activating NF-κB signaling pathway via sponging miR-223-3p to enhance IKKα expression. Thus, SLCO4A1-AS1 might be a promising biomarker for NSCLC treatment.

LncRNA LINC00665 Promotes Prostate Cancer Progression via miR-1224-5p/SND1 Axis

Background

Increasing researches have revealed a critical role of long noncoding RNAs (lncRNAs) in tumor progression. LINC00665 is a poorly investigated lncRNA. In this research, we sought to determine the potential role of LINC00665 in prostate cancer (PC) progression.

Methods

LINC00665 expression was analyzed by bioinformatics method and qRT-PCR. Proliferation was determined via CCK8 and colony formation assays. Transwell assay was conducted to analyze migration and invasion. Xenograft assay was used to test the roles of LINC00665 in vivo. Luciferase reporter assay, pulldown assay and RIP assay were utilized to confirm the interaction between LINC00665 and miR-1224-5p.

Results

LINC00665 expression was increased in PC samples in contrast to control tissues, according to bioinformatics analysis and qRT-PCR validation. LINC00665 high expression was related to a poor prognosis. LINC00665 knockdown markedly attenuated growth and metastasis of PC cells and impaired tumor propagation in vivo. Mechanistic investigation revealed that LINC00665 was the sponge for miR-1224-5p. By inhibiting miR-1224-5p level, LINC00665 dramatically promoted the expression of SND1 in PC cells. Ectopic expression of SND1 significantly rescued the effects of LINC00665 silencing.

Conclusion

LINC00665 is a novel oncogenic gene in PC by targeting miR-1224-5p/SND1 pathway and may be a therapeutic target.

LINC01232 exerts oncogenic activities in pancreatic adenocarcinoma via regulation of TM9SF2

Pancreatic adenocarcinoma (PAAD), one of the most prevailing malignant tumors in digestive system, is identified as one of the main culprits of cancer-associated mortality. Despite long intergenic non-protein coding RNA 1232 (LINC01232) is found to be upregulated in TCGA PAAD tissues and associated with poor prognosis, the potential of LINC01232 in PAAD progression still needs more explorations. In this study, LINC01232 was chosen to be the research object in PAAD cellular processes. Functionally, loss-of function assays were carried out and the experimental results indicated that suppression of LINC01232 hindered the deterioration of PAAD by affecting cell proliferation and migration. Furthermore, relationship between LINC01232 and its nearby gene transmembrane 9 superfamily member 2 (TM9SF2) was investigated. The same expression pattern of TM9SF2 in TCGA PAAD samples was observed. It was found that upregulation of LINC01232 could be a crucial factor for the dysregulation of TM9SF2. Mechanistically, LINC01232 recruited EIF4A3 to boost TM9SF2 mRNA stability. Besides, our findings demonstrated that the transcriptional activation of LINC01232 and TM9SF2 was mediated by SP1. Therefore, we concluded that LINC01232 executed carcinogenic properties in PAAD progression via regulation of TM9SF2. In conclusion, this study was the first to unveil the role and molecular mechanism of LINC01232, suggesting LINC01232 as a promising molecular target for pancreatic cancer treatment.

Cancer-related long noncoding RNAs show aberrant expression profiles and competing endogenous RNA potential in esophageal adenocarcinoma

Long non-coding RNAs (lncRNAs) govern gene expression by competitively binding to microRNA response elements (MREs). Although they were initially considered as transcriptional noise, lncRNAs have attracted increased attention in oncology. Dysregulation of lncRNAs occurs in various types of human tumor, including esophageal adenocarcinoma (EAC). However, the functions of these cancer-associated lncRNAs and of their related competitive endogenous RNA (ceRNA) network in EAC remains unknown. To determine the relevant potential mechanisms, the present study analyzed the transcriptome sequencing data and clinical information of 79 patients with EAC, including 79 tumor samples and 11 normal samples, which were obtained from The Cancer Genome Atlas esophageal cancer project. The edgeR v3.25.0 software was used for differential gene expression analysis. The results exhibited 561 cancer-associated lncRNAs with a >2.0-fold change and a false discovery rate-adjusted P<0.01. Among these lncRNAs, 26 were significantly associated with patient overall survival. According to data from bioinformatics databases and differentially expressed RNAs, an lncRNA-regulated ceRNA network for EAC was constructed. The results demonstrated that the aberrantly expressed lncRNA-associated ceRNA network included 37 EAC cancer-associated lncRNAs, five miRNAs and 13 mRNAs. In conclusion, the present study identified novel lncRNAs as candidate prognostic biomarkers and revealed a potential regulatory network of gene expression in EAC.