Overexpression of the long noncoding RNA CCAT1 promotes metastasis via epithelial-to-mesenchymal transition in lung adenocarcinoma

Non-coding RNA in exosomes: Regulating bone metastasis of lung cancer and its clinical application prospect

Lung cancer is a highly prevalent malignancy with poor prognosis and rapid progression. It most frequently metastasizes to the bone, where it can pose a severe threat to the patient's survival. Once metastasized, the disease is often incurable and can result in severe complications such as hypercalcemia, bone pain, fractures, spinal cord compression, and subsequent paralysis. Exosomes are bilayer vesicle nanoparticles secreted by most of the extracellular vesicles, which can be found in almost all organisms and play an essential role in intercellular communication. Through their ability to regulate related bone cells, exosomes carry bioactive molecules, including proteins, lipids, and non-coding RNAs (ncRNAs), that can be extremely important in bone remodeling. Studies have been conducted on the role play by proteins, lncRNA, and microRNA-all ncRNAs-carried by exosomes in the bone metastases of lung cancer. In this review, the latest progress of the regulatory mechanism of ncRNAs carried by exosomes in lung cancer bone metastasis has been reviewed. The clinical use of exosomes as a promising biomarker, drug transporter, and therapeutic target was highlighted to offer a novel diagnostic and treatment approach for patients with lung cancer bone metastases.

Long non-coding RNA CCAT1 acts as an oncogene to promote radiation resistance in lung adenocarcinoma: an epigenomics-based investigation

Long non-coding RNAs (lncRNAs) appear to be the crucial modulators in various processes and critically influence the oncogenesis. As one of the LncRNAs, LncRNA CCAT1 has been reported to be closely associated with the progression multiple cancers, but its role in modulating the radioresistance of lung adenocarcinoma (LUAD) remains unclear. In our present study, we screened the potential radioresistance related LncRNAs in LUAD based on the data from The Cancer Genome Atlas (TCGA) database. Data suggested that CCAT1 was abundantly expressed in LUAD and CCAT1 was significantly associated with poor prognosis and radioresistance. Moreover, our in vitro experiments showed that radiation treatment could trigger elevated expression of CCAT1 in the human LUAD cell lines. Further loss/gain-of-function investigations indicated that CCAT1 knockdown significantly inhibited cell proliferation, migration and promoted cell apoptosis in NCI-H1299 cells under irradiation, whereas CCAT1 overexpression in A549 cells yield the opposite effects. In summary, we identified the promoting role of CCAT1 in radioresistance of LUAD, which may provide a theoretical basis for radiotherapy sensitization of LUAD.

CCAT 1- A Pivotal Oncogenic Long Non-Coding RNA in Colorectal Cancer

Colorectal cancer (CRC) is ranked as the third most common cancer and second deadliest cancer in both men and women in the world. Currently, the cure rate and 5-year survival rate of CRC patients remain relatively low. Therefore, discovering a novel molecular biomarker that can be used to improve CRC screening, diagnosis, prognosis, and treatment would be beneficial. Long non-coding RNA colon cancer-associated transcript 1 (CCAT 1) has been found overexpressed in CRC and is associated with CRC tumorigenesis and treatment outcome. CCAT 1 has a high degree of specificity and sensitivity, it is readily detected in CRC tissues and is significantly overexpressed in both premalignant and malignant CRC tissues. Besides, CCAT 1 is associated with clinical manifestation and advanced features of CRC, such as lymph node metastasis, high tumor node metastasis stage, differentiation, invasion, and distant metastasis. In addition, they can upregulate oncogenic c-MYC and negatively modulate microRNAs via different mechanisms of action. Furthermore, dysregulated CCAT 1 also enhances the chemoresistance in CRC cells while downregulation of them reverses the malignant phenotypes of cancer cells. In brief, CCAT 1 serves as a potential screening, diagnostic and prognostic biomarker in CRC, it also serves as a potential therapeutic marker to treat CRC patients.

Non-Coding RNAs of Extracellular Vesicles: Key Players in Organ-Specific Metastasis and Clinical Implications

Extracellular vesicles (EVs) are heterogeneous membrane-encapsulated vesicles released by most cells. They act as multifunctional regulators of intercellular communication by delivering bioactive molecules, including non-coding RNAs (ncRNAs). Metastasis is a major cause of cancer-related death. Most cancer cells disseminate and colonize a specific target organ via EVs, a process known as "organ-specific metastasis". Mounting evidence has shown that EVs are enriched with ncRNAs, and various EV-ncRNAs derived from tumor cells influence organ-specific metastasis via different mechanisms. Due to the tissue-specific expression of EV-ncRNAs, they could be used as potential biomarkers and therapeutic targets for the treatment of tumor metastasis in various types of cancer. In this review, we have discussed the underlying mechanisms of EV-delivered ncRNAs in the most common organ-specific metastases of liver, bone, lung, brain, and lymph nodes. Moreover, we summarize the potential clinical applications of EV-ncRNAs in organ-specific metastasis to fill the gap between benches and bedsides.

Integrin α6 overexpression promotes lymphangiogenesis and lymphatic metastasis via activating the NF-κB signaling pathway in lung adenocarcinoma

OBJECTIVE

It has been reported that tumor-associated lymphangiogenesis plays an important role in lymph node metastasis and contributes to the poor survival of lung adenocarcinoma (LUAD) patients. As yet, however, the molecular mechanism underlying LUAD-associated lymphangiogenesis has remained elusive.

METHODS

Immunohistochemistry (IHC) was used to determine the expression of integrin subunit alpha 6 (ITGA6) and the lymphatic vessel endothelial hyaluronan receptor 1 (Lyve1) in clinicopathologically characterized LUAD specimens. The effect of ITGA6 overexpression on lymphangiogenesis and lymphatic metastasis was examined by tube formation, scratch wound-healing, and cell migration assays in vitro and a popliteal lymph node metastasis model in vivo. Mechanistically, overexpression of ITGA6 and activation of NF-κB signaling were examined by real-time PCR, ubiquitination and dual-luciferase reporter assays. Finally, high ITGA6 expression in LUAD tissue samples was related to copy number variation (CNV) using the TCGA database.

RESULTS

We found that ITGA6 overexpression correlated with microlymphatic vessel density in LUAD specimens (p < 0.01). Importantly, by using a popliteal lymph node metastasis model, we found that ITGA6 upregulation significantly enhanced lymphangiogenesis and lymphatic metastasis in vivo (p < 0.05). In addition, we found that ITGA6 overexpression enhanced the capability of A549 and H1299 LUAD cells to induce tube formation and migration in human lymphatic endothelial cells (HLECs). Mechanistically, we found that ITGA6 sustained NF-κB activity via binding and promoting K63 polyubiquitination of TNF receptor-associated factor 2 (TRAF2). Finally, CNV analysis revealed ITGA6 amplification of 27.5% in the LUAD tissue samples in the TCGA database.

CONCLUSIONS

Taken together, our results uncover a plausible role for ITGA6 in mediating lymphangiogenesis and lymphatic metastasis and may provide a basis for targeting ITGA6 to treat LUAD lymphatic metastasis.

Long non-coding RNA CCAT1 promotes non-small cell lung cancer progression by regulating the miR-216a-5p/RAP2B axis

The long non-coding RNA colon cancer-associated transcript 1 (CCAT1) has been investigated to involve in the progression of non-small cell lung cancer (NSCLC). Thus, this study aims to explore the detailed molecular mechanisms of CCAT1 in NSCLC. The expression of CCAT1, miR-216a-5p, RAP2B, Bax, Bcl-2, and cleaved caspase 3 was detected by qRT-PCR or Western blot. Cell proliferation, apoptosis, migration, and invasion were analyzed using cell counting kit-8, flow cytometry or Transwell assays, respectively. The interaction between miR-216a-5p and CCAT1 or RAP2B was analyzed by luciferase reporter, RNA immunoprecipitation, and pull-down assays. The expression of CCAT1 was elevated in NSCLC, and CCAT1 deletion could inhibit NSCLC cell proliferation, migration, and invasion but induce apoptosis in vitro as well as imped tumor growth in vivo. MiR-216a-5p was confirmed to be a target of CCAT1, and silencing miR-216a-5p could reverse CCAT1 depletion-mediated inhibitory effects on cell tumorigenesis in NSCLC. Besides that, miR-216a-5p was decreased in NSCLC, and miR-216a-5p restoration inhibited cell tumorigenesis by regulating RAP2B, which was verified to be a target of miR-216a-5p. Additionally, co-expression analysis suggested that CCAT1 indirectly regulated RAP2B level by targeting miR-216a-5p in NSCLC cells. Taken together, CCAT1 deletion could inhibit cell progression in NSCLC through miR-216a-5p/RAP2B axis, indicating a novel pathway underlying NSCLC cell progression and providing new potential targets for NSCLC treatment.

IDSSIM: an lncRNA functional similarity calculation model based on an improved disease semantic similarity method

Background

It has been widely accepted that long non-coding RNAs (lncRNAs) play important roles in the development and progression of human diseases. Many association prediction models have been proposed for predicting lncRNA functions and identifying potential lncRNA-disease associations. Nevertheless, among them, little effort has been attempted to measure lncRNA functional similarity, which is an essential part of association prediction models.

Results

In this study, we presented an lncRNA functional similarity calculation model, IDSSIM for short, based on an improved disease semantic similarity method, highlight of which is the introduction of information content contribution factor into the semantic value calculation to take into account both the hierarchical structures of disease directed acyclic graphs and the disease specificities. IDSSIM and three state-of-the-art models, i.e., LNCSIM1, LNCSIM2, and ILNCSIM, were evaluated by applying their disease semantic similarity matrices and the lncRNA functional similarity matrices, as well as corresponding matrices of human lncRNA-disease associations coming from either lncRNADisease database or MNDR database, into an association prediction method WKNKN for lncRNA-disease association prediction. In addition, case studies of breast cancer and adenocarcinoma were also performed to validate the effectiveness of IDSSIM.

Conclusions

Results demonstrated that in terms of ROC curves and AUC values, IDSSIM is superior to compared models, and can improve accuracy of disease semantic similarity effectively, leading to increase the association prediction ability of the IDSSIM-WKNKN model; in terms of case studies, most of potential disease-associated lncRNAs predicted by IDSSIM can be confirmed by databases and literatures, implying that IDSSIM can serve as a promising tool for predicting lncRNA functions, identifying potential lncRNA-disease associations, and pre-screening candidate lncRNAs to perform biological experiments. The IDSSIM code, all experimental data and prediction results are available online at https://github.com/CDMB-lab/IDSSIM.

Knockdown of lncRNA CCAT1 enhances sensitivity of paclitaxel in prostate cancer via regulating miR-24-3p and FSCN1

Drug resistance limits the efficacy of chemotherapy in human cancers. Previous studies reported that long noncoding RNA colon cancer-associated transcript 1 (CCAT1) regulated progression of prostate cancer (PCa). However, the potential role of CCAT1 in the sensitivity of paclitaxel (PTX) in PCa and its mechanism remain largely unknown. The PTX-resistant PCa cells were established in PC3 and DU145 cells by increasing concentrations of PTX. The expressions of CCAT1, microRNA-24-3p (miR-24-3p) and fascin1 (FSCN1) were measured by quantitative real-time polymerase chain reaction. The viability and apoptosis were detected by 3-(4,5-dimethyl-2-thiazolyl)-2,5-diphenyl-2-H-tetrazolium bromide assay, flow cytometry and western blot, respectively. The interaction among CCAT1, miR-24-3p and FSCN1 was explored by luciferase activity, RNA immunoprecipitation, RNA pull-down and western blot, respectively. Results showed that the expressions of CCAT1 were up-regulated and miR-24-3p was down-regulated in PCa and PTX-resistant PCa cells (PC3-TXR and DU145-TXR). Knockdown of CCAT1 or overexpression of miR-24-3p inhibited survival rate, half maximal inhibitory concentration (IC50) of PTX but increased apoptosis in PC3-TXR and DU145-TXR cells after treatment of PTX. miR-24-3p was bound to CCAT1 and its abrogation reversed knockdown of CCAT1-mediated increase of PTX sensitivity in PC3-TXR and DU145-TXR cells. Moreover, FSCN1 restoration attenuated miR-24-3p-mediated inhibition of PTX resistance. Besides, FSCN1 level was enhanced in PCa and PTX-resistant PCa cells and regulated by CCAT1 and miR-24-3p. Our data suggested interference of CCAT1 contributed to PTX sensitivity in PCa by regulating miR-24-3p and FSCN1, indicating a novel avenue for treatment of PCa through regulating chemoresistance.

Combined identification of LncRNA CCAT1 and SOX2OT in serum as an effective screening for non-small cell lung cancer

BACKGROUND

Long non-coding RNAs (lncRNAs) CCAT1 and SOX2OT have been shown to play important regulatory roles in cancer biology. Tumor biomarkers need to be detectable in easily accessible body fluids, should be characterized by high specificity, sufficient sensitivity, and robustness against influencing factors. The aim of this study is to evaluate the clinical significance of serum CCAT1 and SOX2OT as a biomarker in the screening of NSCLC.

RESULTS

CCAT1 and SOX2OT were shown to be detectable in the cellular fraction of peripheral human blood, showing serum levels of CCAT1 and SOX2OT were significantly increased of cancer patients as compared to cancer-free controls. The ROC curves illustrated strong separation between the NSCLC patients and control group, with an AUC of 0.846 (95% CI 0.766-0.926; P < 0.001) for CCAT1 and 0.787 (95% CI: 0.691-0.883; P < 0.001) for SOX2OT. However, the combination of SOX2OT and CCAT1 yielded an AUC of 0.894 (95% CI: 0.825-0.963; P < 0.001), which was significantly improved as compared to CCAT1 or SOX2OT alone. Moreover, the interaction between lncRNAs and some functional proteins, such as TTF1, p63, Ck7, K-ras, EGFR, may contribute to the tumorigenesis.

CONCLUSION

Our results demonstrated that increased serum CCAT1 and SOX2OT could be used as a predictive biomarker for NSCLC screening, and that combination of CCAT1 and SOX2OT had a higher positive diagnostic efficiency of NSCLC than CCAT1 or SOX2OT alone.

LncRNA LUCAT1 facilitates tumorigenesis and metastasis of triple-negative breast cancer through modulating miR-5702

Triple-negative breast cancer (TNBC) is a subtype of aggressive breast cancer with high recurrence and poor survival. Emerging evidence has indicated that long non-coding RNAs (lncRNAs) play pivotal roles in the development and progression of multiple cancers. Although there are substantial studies revealing that lung cancer-associated transcript 1 (LUCAT1) functions as a tumor promotor in various human cancers, the molecular mechanism of LUCAT1 in TNBC remains largely to be explored. In our study, we identified that LUCAT1 expression was dramatically enhanced in TNBC samples and cells. High LUCAT1 expression was strongly associated with advanced stages and poor prognosis of TNBC. LUCAT1 contributed to TNBC development through accelerating cell proliferation, cell cycle progression and metastasis as well as attenuating cell apoptosis. Moreover, miR-5702 was proved to directly bind to LUCAT1 and be negatively modulated by LUCAT1. Knockdown of miR-5702 reversed the suppressing influences of LUCAT1 depletion on TNBC progression. In conclusion, it was the first investigation to shed light on the significant function and underlying regulatory mechanism of LUCAT1 in TNBC tumorigenesis. We validated that LUCAT1 induced tumorigenesis and metastasis of TNBC via miR-5702, which provided clues for improving the treatment of TNBC.

Long non-coding RNA OECC promotes cell proliferation and metastasis through the PI3K/Akt/mTOR signaling pathway in human lung cancer

Lung cancer is one of the most common malignancies worldwide; however, its detailed molecular mechanism remains largely unknown. Long non-coding RNAs (lncRNAs) have been identified to serve critical roles in tumorigenesis. The aim of the present study was to investigate the role of a newly identified lncRNA, overexpressed in colorectal cancer (OECC), in human lung cancer. It was initially revealed that the relative transcript level of OECC was highly upregulated in clinical human lung cancer tissues as well as in cultured lung cancer cells. Knockdown of OECC with specific short hairpin RNAs in lung cancer cell lines A549 and 95D inhibited colony formation and cell viability, as evidenced using colony formation assays and cell proliferation assays. Furthermore, depletion of OECC in A549 and 95D cells suppressed migration and invasion, which was verified using Transwell assays. RNA-sequence analysis suggested that the phosphoinositide 3-kinase/protein kinase B (Akt)/mammalian target of rapamycin signaling pathway was positively regulated by OECC in lung cancer cells A549. In addition, overexpression of Akt in OECC-depleted A549 and 95D cells reversed the suppression of proliferation and migration caused by OECC depletion. The results of the present study identified lncRNA OECC as a novel regulator of lung cancer progression and provided new clues for the clinical treatment of lung cancer.

Long non-coding RNA CCAT1 promotes cervical cancer cell proliferation and invasion by regulating the miR-181a-5p/MMP14 axis

Cervical cancer is a serious threat to women's health and is the third most common malignancy in women worldwide. Recent studies indicate that the long non-coding RNA CCAT1 plays a role in the malignant behavior of many tumors. However, the role of CCAT1 in cervical cancer is still unknown. Our aim is to evaluate the expression and investigate the regulatory role and potential mechanism of CCAT1 in cervical cancer. CCAT1 expression was measured by qRT-PCR. In addition, CCK-8 assays, colony formation assays, qRT-PCR assays, Transwell assays and xenograft experiments were performed to determine the role of CCAT1 in the proliferation and invasion in cervical cancer cells. The expression of CCAT1 in the cervical cancer tissues was higher than in the adjacent normal tissues. Overexpressing CCAT1 promoted cervical cancer cell proliferation, colony formation, and invasion in vitro. Elevated CCAT1 suppressed miR-181a expression, which was accompanied by an increased expression of MMP14 and HB-EGF. In contrast, knocking down CCAT1 resulted in increased expression of miR-181a, along with decreased expression of MMP14 and HB-EGF. Thus, CCAT1 is a key oncogenic lncRNA associated with cervical cancer and plays a role in promoting cervical cancer cell proliferation and invasion by regulating the miR-181a-5p/MMP14 axis.