lncRNA CASC9 positively regulates CHK1 to promote breast cancer cell proliferation and survival through sponging the miR‑195/497 cluster

Cell cycle related long non-coding RNAs as the critical regulators of breast cancer progression and metastasis

Cell cycle is one of the main cellular mechanisms involved in tumor progression. Almost all of the active molecular pathways in tumor cells directly or indirectly target the cell cycle progression. Therefore, it is necessary to assess the molecular mechanisms involved in cell cycle regulation in tumor cells. Since, early diagnosis has pivotal role in better cancer management and treatment, it is required to introduce the non-invasive diagnostic markers. Long non-coding RNAs (LncRNAs) have higher stability in body fluids in comparison with mRNAs. Therefore, they can be used as efficient non-invasive markers for the early detection of breast cancer (BCa). In the present review we have summarized all of the reported lncRNAs involved in cell cycle regulation in BCa. It has been reported that lncRNAs mainly affect the cell cycle in G1/S transition through the CCND1/CDK4-6 complex. Present review paves the way of introducing the cell cycle related lncRNAs as efficient markers for the early detection of BCa.

LncRNA CASC9 promotes cell proliferation and invasion in osteosarcoma through targeting miR-874-3p/SOX12 axis

BACKGROUND

Osteosarcoma (OS) is a common primary malignant bone tumor. This study aimed to explore the biological role of long on-coding RNA (lncRNA) CASC9 and its regulatory mechanism in OC.

METHODS

The CASC9 expressions in OS cells and tissues were measured using qRT-PCR. The functional role of CASC9 in OC was studied using MTT assay, colony formation assay, transwell invasion assay, and xenograft tumor assay. In addition, the mechanism of CASC9 function was determined using luciferase reporter assay. Western blot was used to analyze protein expressions in our paper.

RESULTS

LncRNA CASC9 was found to be up-regulated in OS. Knockdown of CASC9 inhibited the proliferation and invasion of OS cells. Besides, miR-874-3p was identified as the target of CASC9, and SOX12 acted as a potential target of miR-874-3p. The down-regulation of miR-874-3p recovered the reduction in cell invasion and proliferation in vitro which were induced by CASC9 knockdown and delayed the tumor progression in vivo.

CONCLUSION

LncRNA CASC9 promotes cell proliferation and invasion in OS via miR-874-3p/SOX12 axis. Our study might provide novel biomarkers and potential therapeutic targets for OS treatment.

LINC00355 regulates p27KIP expression by binding to MENIN to induce proliferation in late-stage relapse breast cancer

Late-stage relapse (LSR) in patients with breast cancer (BC) occurs more than five years and up to 10 years after initial treatment and has less than 30% 5-year relative survival rate. Long non-coding RNAs (lncRNAs) play important roles in BC yet have not been studied in LSR BC. Here, we identify 1127 lncRNAs differentially expressed in LSR BC via transcriptome sequencing and analysis of 72 early-stage and 24 LSR BC patient tumors. Decreasing expression of the most up-regulated lncRNA, LINC00355, in BC and MCF7 long-term estrogen deprived cell lines decreases cellular invasion and proliferation. Subsequent mechanistic studies show that LINC00355 binds to MENIN and changes occupancy at the CDKN1B promoter to decrease p27Kip. In summary, this is a key study discovering lncRNAs in LSR BC and LINC00355 association with epigenetic regulation and proliferation in BC.

Tumor-Derived Exosomal Non-Coding RNAs: The Emerging Mechanisms and Potential Clinical Applications in Breast Cancer

Breast cancer (BC) is the most frequent malignancy and is ranking the leading cause of cancer-related death among women worldwide. At present, BC is still an intricate challenge confronted with high invasion, metastasis, drug resistance, and recurrence rate. Exosomes are membrane-enclosed extracellular vesicles with the lipid bilayer and recently have been confirmed as significant mediators of tumor cells to communicate with surrounding cells in the tumor microenvironment. As very important orchestrators, non-coding RNAs (ncRNAs) are aberrantly expressed and participate in regulating gene expression in multiple human cancers, while the most reported ncRNAs within exosomes in BC are microRNAs (miRNAs), long-noncoding RNAs (lncRNAs), and circular RNAs (circRNAs). Notably, ncRNAs containing exosomes are novel frontiers to shape malignant behaviors in recipient BC cells such as angiogenesis, immunoregulation, proliferation, and migration. It means that tumor-derived ncRNAs-containing exosomes are pluripotent carriers with intriguing and elaborate roles in BC progression via complex mechanisms. The ncRNAs in exosomes are usually excavated based on specific de-regulated expression verified by RNA sequencing, bioinformatic analyses, and PCR experiments. Here, this article will elucidate the recent existing research on the functions and mechanisms of tumor-derived exosomal miRNA, lncRNA, circRNA in BC, especially in BC cell proliferation, metastasis, immunoregulation, and drug resistance. Moreover, these tumor-derived exosomal ncRNAs that existed in blood samples are proved to be excellent diagnostic biomarkers for improving diagnosis and prognosis. The in-depth understanding of tumor-derived exosomal ncRNAs in BC will provide further insights for elucidating the BC oncogenesis and progress and exploring novel therapeutic strategies for combating BC.

The lncRNA CASC9 alleviates lipopolysaccharide-induced acute kidney injury by regulating the miR-424-5p/TXNIP pathway

OBJECTIVE

This study aimed to clarify the mechanism by which the long non-coding RNA cancer susceptibility candidate 9 (CASC9) alleviates sepsis-related acute kidney injury (S-AKI).

METHODS

A lipopolysaccharide (LPS)-induced AKI model was established to simulate S-AKI. HK-2 human renal tubular epithelial cells were treated with LPS to establish an in vitro model, and mice were intraperitoneally injected with LPS to generate an in vivo model. Subsequently, the mRNA expression of inflammatory and antioxidant factors was validated by quantitative reverse transcription polymerase chain reaction (RT-qPCR). Reactive oxygen species (ROS) production was assessed using an assay kit. Apoptosis was detected by western blotting and fluorescence-activated cell sorting.

RESULTS

CASC9 was significantly downregulated in the LPS-induced AKI model. CASC9 attenuated cell inflammation and apoptosis and enhanced the antioxidant capacity of cells. Regarding the mechanism, miR-424-5p was identified as the downstream target of CASC9, and the interaction between CASC9 and miR-424-5p promoted thioredoxin-interacting protein (TXNIP) expression.

CONCLUSIONS

CASC9 alleviates LPS-induced AKI in vivo and in vitro, and CASC9 directly targets miR-424-5p and further promotes the expression of TXNIP. We have provided a possible reference strategy for the treatment of S-AKI.

Oncogenic LncRNA CASC9 in Cancer Progression

BACKGROUND

Long non-coding RNAs (LncRNAs), with the length of over 200 nucleotides, that originate from intergenic, antisense, or promoter-proximal regions, are a large family of RNAs that lack coding capacity. Emerging evidences illustrated that LncRNAs played significant roles in a variety of cellular functions and biological processes in profuse human diseases, especially in cancers. Cancer susceptibility candidate 9 (CASC9), as a member of the LncRNAs group, firstly found its oncogenic function in esophageal cancer. In the following recent studies, a growing amount of human malignancies are verified to be correlated with CASC9, most of which are derived from the squamous epithelium tissue. This present review attempts to highlight the latest insights into the expression, functional roles, and molecular mechanisms of CASC9 in different human malignancies.

METHODS

In this review, the latest findings related to the pathophysiological processes of CASC9 in human cancers were summarized and analyzed, and the associated studies collected in systematic retrieval of PubMed used lncRNA and CASA9 as keywords.

RESULTS

CASC9 expression is identified to be aberrantly elevated in a variety of malignancies. The over-expression of CASC9 has been suggested to accelerate cell proliferation, migration, cell growth and drug resistance of cancer cells, while depressing cell apoptosis, revealing its role as an oncogene. Moreover, the current review demonstrated CASC9 as closely related to the neoplastic transformation of squamous epithelial cells and squamous metaplasia in non-squamous epithelial tissues. Finally, we discuss the limitations and tremendous diagnostic/ therapeutic potential of CASC9 in various human cancers.

CONCLUSION

Long non-coding RNA CASC9 likely serve as useful disease biomarkers or therapeutic targets which be effectively applied in the treatment of different kinds of cancers.

Long Non-Coding RNA NORAD Inhibits Breast Cancer Cell Proliferation and Metastasis by Regulating miR-155-5p/SOCS1 Axis

Purpose

Non-coding RNA activated by DNA damage (NORAD) has been reported to be a cancer-related long non-coding RNA (lncRNA) implicated in the progression of several cancers; however, its role in breast cancer (BC) has not yet been clarified.

Methods

Quantitative real-time polymerase chain reaction was used to examine NORAD, microRNA (miR)-155-5p, and suppressor of cytokine signaling 1 (SOCS1) mRNA expression levels. Western blotting was used to analyze SOCS1 protein expression. The malignancy of BC cells was assessed using the cell counting kit-8 (CCK-8), BrdU, and Transwell assays. Bioinformatics analysis, RNA immunoprecipitation assay, and dual-luciferase reporter gene assays were used to verify the targeted relationship between NORAD and miR-155-5p. Additionally, the regulatory effects of NORAD and miR-155-5p on SOCS1 expression were determined by western blotting.

Results

NORAD expression was significantly reduced in BC cell lines and tissues, and its low expression was associated with poor tumor tissue differentiation. NORAD overexpression repressed BC cell proliferation, migration, and invasion, whereas its knockdown produced the opposite effects. Additionally, miR-155-5p was found to be a target of NORAD, and the biological functions of miR-155-5p and NORAD were counteractive. MiR-155-5p was confirmed to target SOCS1, and SOCS1 was found to be positively regulated by NORAD.

Conclusion

NORAD suppresses miR-155-5p to upregulate SOCS1, thereby repressing the proliferation, migration, and invasion of BC cells.

Silencing long non-coding RNA CASC9 inhibits colorectal cancer cell proliferation by acting as a competing endogenous RNA of miR-576-5p to regulate AKT3

Increasing studies have shown that long non-coding RNAs (lncRNAs) are regarded as important regulators in the occurrence and development of colorectal cancer (CRC). Although lncRNA CASC9 has been studied in CRC, the detailed regulatory mechanism of CASC9 in CRC is still unclear. In this study, we found that CASC9 was significantly upregulated in CRC tissues and cell lines compared to normal controls and that aberrant expression was associated with the tumor-node-metastasis (TNM) stage of CRC. Functionally, CASC9 depletion efficiently inhibited the proliferation of CRC cells and induced cell apoptosis in vitro. Mechanistically, CASC9 was mainly enriched in the cytoplasm of CRC cells and interacted directly with miR-576-5p. Downregulation of miR-576-5p reversed the inhibitory effect of CASC9 siRNA on CRC cell progression. Furthermore, AKT3 has been identified as a downstream target of miR-576-5p. Spearman’s correlation analysis revealed that AKT3 was negatively correlated with miR-576-5p but positively correlated with CASC9. Downregulation of miR-576-5p restored the effect of CASC9 silencing on AKT3 expression. Therefore, silencing CASC9 could downregulate the expression of AKT3 by reducing the competitive binding of CASC9 to miR-576-5p, thus suppressing CRC cell proliferation and promoting cell apoptosis. In summary, we identified CASC9 as an oncogenic lncRNA in CRC and defined the CASC9/miR-576-5p/AKT3 axis, which might be considered a potential therapeutic target for CRC patients, as a novel molecular mechanism implicated in the proliferation and apoptosis of CRC.

Clinicopathological association and prognostic value of long non-coding RNA CASC9 in patients with cancer: A meta-analysis

Several studies have reported a prognostic role of the long non-coding RNA (lncRNA) cancer susceptibility candidate 9 (CASC9) in various cancer types, but its clinical significance has remained inconclusive. The aim of the present meta-analysis was to evaluate the impact of CASC9 expression on the prognosis and clinicopathological features of patients with cancer patients. The PubMed, Embase, Cochrane Library and Web of Science databases were searched for relevant literature and eight studies, including 565 patients with cancer, were selected. The quality of these studies was appraised with the Newcastle-Ottawa Scale (NOS) and the association between CASC9 expression and prognosis or clinicopathological features was analyzed. Patients with high expression levels of CASC9 in their tumor tissues had a lower overall survival rate compared with those in the low CASC9 expression group (hazard ratio=2.25, 95% CI: 1.60-3.17, P<0.001). Furthermore, elevated CASC9 expression was significantly associated with deeper tumor invasion [odds ratio (OR)=2.66, 95% CI: 1.72-4.14, P<0.001], poor tumor differentiation (OR=2.44, 95% CI: 1.24-4.78, P=0.009), lymph node metastasis (OR=3.42, 95% CI: 1.98-5.92, P<0.001) and advanced clinical stage (OR=3.21, 95% CI: 2.21-4.66, P<0.001). In conclusion, CASC9 is a promising biomarker for predicting the prognosis of cancer patients and should be validated in the clinic.

Long-Noncoding RNA CASC9 Promotes Progression of Non-Small Cell Lung Cancer by Promoting the Expression of CDC6 Through Binding to HuR

OBJECTIVE

The long-noncoding RNAs (lncRNAs) have been identified as key players in diverse cellular processes in non-small cell lung cancer (NSCLC). However, the understanding of biological functions and detailed mechanisms of lncRNAs is still limited. Herein, the lncRNA cancer susceptibility candidate 9 (CASC9) on NSCLC progression is investigated.

MATERIALS AND METHODS

Expressions of CASC9, HuR and cell division cycle 6 (CDC6) in NSCLC tissues were detected with quantitative real-time polymerase chain reaction (qRT-PCR). The cell counting kit-8, transwell assays, and flow cytometry were used to examine cell proliferation, migration, and the cell cycle. Tumor growth in vivo was evaluated by xenograft tumor experiments and immunohistochemistry. RNA-binding protein immunoprecipitation (RIP) was used to identify the interaction between HuR and CDC6, and CASC9 and HuR.

RESULTS

CASC9, CDC6 and HuR expression were found significantly upregulated in NSCLC tissues, which predicted poorer 5-year overall survival in NSCLC patients. Inhibition of CASC9 significantly reduced the malignancy of NSCLC cells, such as proliferation, migration and cell cycle. In vivo experiments further demonstrated that CASC9 knockdown reduced the tumor growth and the Ki-67 expression. Moreover, CASC9 knockdown inhibited the expression of CDC6 which was detected overexpressed in NSCLC tumor tissues. Then, up-regulation of CDC6 could partly reverse the negative effects of CASC9 on cell proliferation, migration and cell cycle. RIP assay and rescue experiment showed that CASC9 regulated CDC via binding to HuR.

CONCLUSION

Our results indicate that CASC9 conferred an aggressive phenotype in NSCLC and might be a pivotal target for this disease.

Cancer Susceptibility Candidate 9 (CASC9): A Novel Targetable Long Noncoding RNA in Cancer Treatment

Based on epidemiological data provided by the World Health Organization (2018), cancer is the second most prevalent cause of death worldwide. Several factors are thought to contribute to the high mortality rate in cancer patients, including less-than-optimal diagnostic and therapeutic strategies. Thus, there is an urgent need to identify accurate biomarkers with diagnostic, prognostic, and potential therapeutic applications. In this regard, long noncoding RNAs (lncRNAs) hold immense potential due to their regulatory roles in cancer development and associated cancer hallmarks. Recently, CASC9 transcripts have attracted significant attention due to their altered expression during the pathogenesis of cancer and their apparent contributions to various cancer-associated phenotypes involving a broad spectrum of molecular mechanisms. Here, we have provided an in-depth review describing the known functions of the lncRNA CASC9 in cancer development and progression.

Determination of Serum Exosomal H19 as a Noninvasive Biomarker for Breast Cancer Diagnosis

Purpose

There is an urgent need for new biomarkers for the diagnosis of breast cancer. Exosomes can communicate with cells through transport molecules, including long-chain noncoding RNA (lncRNA), which is considered as a promising noninvasive biomarker. Here, we aimed to determine the potential of long noncoding RNA (lncRNA) H19 in the circulating exosomes for the diagnosis of breast cancer (BC).

Materials and Methods

We measured the levels of lncRNA H19 in serum-derived exosomes from patients with breast cancer (BC) or benign breast disease (BBD) and healthy subjects, using quantitative real-time PCR. H19 levels were also measured for pre-operative and post-operative patients. Receiver operating characteristic curve was constructed, and the area under the curve (AUC) was calculated to determine the applicability of exosomal H19 levels as biomarkers in BC. The relationship between H19 relative expression and clinical features of BC patients was also analyzed.

Results

Exosomal H19 expression levels were upregulated in patients with BC compared to that in patients with BBD and healthy controls (BC vs BBD, P < 0.001; BC vs healthy subjects, P < 0.001). The median serum exosomal H19 levels were significantly lower in post-operative than that in the pre-operative patients (P < 0.001). The AUC for exosomal H19 analysis was 0.870 (95% CI: 0.774–0.966) with a sensitivity of 87.0% and specificity of 70.6%, which was higher than the AUCs for CA15-3 and CEA, ie, 0.822 and 0.811, respectively. Moreover, exosomal H19 expression levels were associated with lymph node metastasis (P = 0.039), distant metastasis (P = 0.008), TNM stages (P = 0.022), ER (P=0.009), PR (P = 0.018), and Her-2 (P = 0.021).

Conclusion

Our results indicated that serum exosomal H19 acts as a novel biomarker for the diagnosis of BC.

lncRNA NEAT1 Facilitates Cell Proliferation, Invasion and Migration by Regulating CBX7 and RTCB in Breast Cancer

Purpose

To investigate the association between the lncRNA NEAT1 and breast cancer, and to determine the influence of NEAT1 on regulation of other signaling molecules in breast cancer.

Methods

In the present study, we measured levels of the lncRNA NEAT1 in 106 breast cancer patients and in a human breast cancer cell line by qRT-PCR. The correlation between NEAT1 expression and patients’ clinical characteristics was analyzed with in-house and TCGA data. We used cellular functioning assays and cell immunofluorescence assay to evaluate the role of NEAT1 and its target molecules in proliferation, invasion and migration in breast cancer. We used Western blotting to explore possible targets of NEAT1 and a subcellular fractionation assay to locate NEAT1 expression.

Results

NEAT1 was overexpressed in breast cancer tissue and also closely related to advanced clinical stages and positive lymph node metastases. NEAT1 levels were also tightly correlated to prognosis for breast cancer patients in survival analyses. Cellular function assays revealed that downregulation of NEAT1 could inhibit breast cancer cell viability, invasion and migration. Western blotting revealed down-regulation of CBX7 and up-regulation of RTCB following NEAT1 inhibition. Based on the cytoplasmic and nuclear expression of NEAT1, we investigated the possible regulation of CBX7 and RTCB by NEAT1. Results showed that NEAT1 regulated the expression of CBX7 and RTCB, possibly by binding of NEAT1 to DNA in the nucleus, which facilitates cell proliferation, invasion and migration.

Conclusion

The current results suggest that the lncRNA NEAT1 is upregulated in breast cancer and facilitates tumor cell viability, invasion and migration via CBX7 and RTCB.

Long noncoding RNA CASC9 promotes the proliferation and metastasis of papillary thyroid cancer via sponging miR-488-3p

Cancer susceptibility candidate 9 (CASC9) is a recently identified lncRNA that acted as a tumor promotor in diversified cancer types. However, its role in papillary thyroid cancer (PTC) remains unknown. The expression of CASC9 was measured in 52 human PTC tissues and PTC cell lines as well as their controls. The proliferation, migration, and invasion of PTC cells were determined after knockdown or overexpression of CASC9 to evaluate the effect of CASC9 on PTC cells. Also, the role of PTC tumorigenesis was confirmed in mice xenograft models. Additionally, the underlying mechanisms of CASC9 were further researched. We found that CASC9 expression was augmented in human PTC tissues and cells. Higher CASC9 expression was associated with large tumor size, advanced stage, or lymph node metastasis. Downregulation of CASC9 significantly attenuated the proliferative, migrative, and invasive abilities of PTC cells, and suppressed tumorigenesis in vivo. While overexpression of CASC9 elevated the proliferation, migration, and invasion of PTC cells. miR‐488‐3p expression was decreased, and ADAM9 level was increased in PTC tissues and cells. CASC9 expression was negatively related to miR‐488‐3p, but positively associated with ADAM9 expression in PTC tissues. Molecular mechanism analysis revealed that CASC9 functioned via sponging miR‐488‐3p to regulate ADAM9 expression, followed by activation of EGFR‐Akt signaling. In conclusion, lncRNA CASC9 promoted the malignant phenotypes of PTC via modulating miR‐488‐3p/ADAM9 pathway. This study may provide a novel therapeutic target for the treatment of PTC.

LncRNA CASC9 Suppressed the Apoptosis of Gastric Cancer Cells through Regulating BMI1

Long noncoding RNAs (lncRNAs) play important roles in regulating the apoptosis of gastric cancer (GC) cells. This study aims to investigate the underlying mechanism of lncRNA CASC9 in regulating the apoptosis of GC cells. The expressions of lncRNA and protein in GC tissues and cell lines were detected by qRT-PCR and western blot. GC cell apoptosis was detected by flow cytometry analysis. RNA pull-down and RNA immunoprecipitation (RIP) assays were conducted to verify the interaction between CASC9 and BMI1. LncRNA CASC9 was upregulated in GC tissue and GC cells, and high CASC9 expression was positively correlated with TNM stage and lymph node metastasis. Silencing CASC9 promoted the apoptosis of GC cells. LncRNA CASC9 could interact with BMI1 and positively regulate BMI1 expression. Silencing CASC9 promoted the ubiquitination of BMI1. In addition, lncRNA CASC9 regulated the apoptosis of GC cells through BMI1. Furthermore, interfering CASC9 inhibited the tumor growth of GC. LncRNA CASC9 could interact with BMI1 to regulate the degradation of BMI1, thus to affect the apoptosis of GC cells and suppressed tumor growth.

Upregulation of the long non-coding RNA CASC9 as a biomarker for squamous cell carcinoma

BACKGROUND

Few diagnostic and prognostic biomarkers are available for head-and-neck squamous cell carcinoma (HNSCC). Long non-coding RNAs (lncRNAs) have shown promise as biomarkers in other cancer types and in some cases functionally contribute to tumor development and progression. Here, we searched for lncRNAs useful as biomarkers in HNSCC.

METHODS

Public datasets were mined for lncRNA candidates. Two independent HNSCC tissue sets and a bladder cancer tissue set were analyzed by RT-qPCR. Effects of lncRNA overexpression or downregulation on cell proliferation, clonogenicity, migration and chemosensitivity were studied in HNSCC cell lines.

RESULTS

Data mining revealed prominently CASC9, a lncRNA significantly overexpressed in HNSCC tumor tissues according to the TCGA RNAseq data. Overexpression was confirmed by RT-qPCR analyses of patient tissues from two independent cohorts. CASC9 expression discriminated tumors from normal tissues with even higher specificity than HOTAIR, a lncRNA previously suggested as an HNSCC biomarker. Specificity of HNSCC detection by CASC9 was further improved by combination with HOTAIR. Analysis of TCGA pan-cancer data revealed significant overexpression of CASC9 across different other entities including bladder, liver, lung and stomach cancers and especially in squamous cell carcinoma (SCC) of the lung. By RT-qPCR analysis we furthermore detected stronger CASC9 overexpression in pure SCC of the urinary bladder and mixed urothelial carcinoma with squamous differentiation than in pure urothelial carcinomas. Thus, CASC9 might represent a general diagnostic biomarker and particularly for SCCs. Unexpectedly, up- or downregulation of CASC9 expression in HNSCC cell lines with low or high CASC9 expression, respectively, did not result in significant changes of cell viability, clonogenicity, migration or chemosensitivity.

CONCLUSIONS

CASC9 is a promising biomarker for HNSCC detection. While regularly overexpressed, however, this lncRNA does not seem to act as a major driver of development or progression in this tumor.