Overexpression of cancer susceptibility candidate 2 inhibited progression of hepatocellular carcinoma cells

Emerging role of long noncoding RNAs in recurrent hepatocellular carcinoma

Hepatocellular carcinoma (HCC) remains one of the most frequent types of liver cancer and is characterized by a high recurrence rate. Recent studies have proposed that long non-coding RNAs (lncRNAs) are potential biomarkers in several recurrent tumor types. It is now well understood that invasion, migration, and metastasis are important factors for tumor recurrence. Moreover, some of the known risk factors for HCC may affect the expression levels of several types of lncRNAs and thus affect the recurrence of liver cancer through lncRNA regulation. In this paper, we review the biological functions, molecular mechanisms, and roles of lncRNAs in HCC and summarize current knowledge about lncRNAs as potential biomarkers in recurrent HCC.

LncRNA influence sequential steps of hepatocellular carcinoma metastasis

As a class of new and crucial molecules involved in the regulation of biological function, long noncoding RNA (lncRNA) have obtained widespread attention in recent days. While it was thought that lncRNA would be redundant in the past, it is proved that lncRNA identify a class of molecular that regulate the homeostasis including hepatocellular carcinoma in the present. All kinds of lncRNA have been implicated in a various of diseases, particularly in tumorigenesis and metastasis. But the mechanisms how they act is still not entirely clear. Metastasis is a major factor affecting long-term survival in hepatocellular carcinoma (HCC) patients. Recently, growing numbers of experiments demonstrate that there is close connection between lncRNA and HCC metastasis. Here, we will briefly introduce a series of steps (primary tumor growth, angiogenesis, epithelial-to-mesenchymal transition, invasion, intravasation, survival in circulatory system, extravasation, dormancy and subsequent secondary tumor growth) of tumor metastasis, its classical but promising theories, the role of lncRNA in metastasis and the possible mechanisms involved. LncRNA, as potentially new and important tumor diagnostic and therapeutic molecules, has attracted much attention in recent years.

Long Non-Coding RNAs: Potential Biomarkers and Targets for Hepatocellular Carcinoma Therapy and Diagnosis

Hepatocellular carcinoma (HCC) is one of the leading causes of cancer-related death worldwide. Increasing studies showed that long non-coding RNAs (lncRNAs), a novel class of RNAs that are greater than 200 nucleotides in length but lack the ability to encode proteins, exert crucial roles in the occurrence and progression of HCC. LncRNAs promote the proliferation, migration, invasion, autophagy, and apoptosis of tumor cells by regulating downstream target gene expression and cancer-related signaling pathways. Meanwhile, lncRNA can be used as biomarkers to predict the efficacy of HCC treatment strategies, such as surgery, radiotherapy, chemotherapy, and immunotherapy, and as a potential individualized tool for HCC diagnosis and treatment. In this review, we overview up-to-date findings on lncRNAs as potential biomarkers for HCC surgery, radiotherapy, chemotherapy resistance, target therapy, and immunotherapy, and discuss the potential clinical application of lncRNA as tools for HCC diagnosis and treatment.

lncRNA CASC2 Enhances 131I Sensitivity in Papillary Thyroid Cancer by Sponging miR-155

Long noncoding RNA cancer susceptibility candidate 2 (CASC2) has been reported to play an anticancer role in papillary thyroid cancer (PTC). Radioiodine (¹³¹I) is a common option for the treatment of PTC. However, the role and mechanism of CASC2 in ¹³¹I sensitivity remain unclear. In this study, ¹³¹I-resistant cells were constructed through continuous treatment of ¹³¹I. The expression levels of CASC2 and miR-155 were measured by qRT-PCR. The IC50 of ¹³¹I was analyzed by cell viability using MTT assay. Flow cytometry was conducted to determine cell apoptosis induced by ¹³¹I. The association between CASC2 and miR-155 was evaluated by luciferase assay and RNA immunoprecipitation. A mouse xenograft model was built to explore the effect of CASC2 on the growth of ¹³¹I-resistant PTC cells in vivo. Results showed that CASC2 expression was decreased in PTC tissues and cells, and low expression of CASC2 was associated with poor outcome of patients. CASC2 level was reduced in ¹³¹I-resistant cells. Knockdown of CASC2 inhibited ¹³¹I sensitivity in thyroid cancer cells. Overexpression of CASC2 enhanced ¹³¹I sensitivity in constructed resistant PTC cells. CASC2 was a decoy of miR-155, and CASC2-mediated promotion of ¹³¹I sensitivity was weakened by decreasing miR-155. Abundance of CASC2 inhibited the growth of ¹³¹I-resistant cells in vivo. As a conclusion, CASC2 increases ¹³¹I sensitivity in PTC by sponging miR-155, providing a novel target for the treatment of thyroid cancer patients with ¹³¹I resistance.

Ginsenoside Rg3 suppresses the growth of gemcitabine-resistant pancreatic cancer cells by upregulating lncRNA-CASC2 and activating PTEN signaling

Pancreatic cancer is one of the most fatal malignancies with high mortality. Gemcitabine (GEM)-based chemotherapy is the most important treatment. However, the development of GEM resistance leads to chemotherapy failure. Previous studies demonstrated the anticancer activity of ginsenoside Rg3 in a variety of carcinomas through modulating multiple signaling pathways. In the present study, 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay, colony formation assay, flow cytometry apoptosis assay, Western blotting assay, xenograft experiment, and immunohistochemistry assay were performed in GEM-resistant pancreatic cancer cell lines. Ginsenoside Rg3 inhibited the viability of GEM-resistant pancreatic cancer cells in a time-dependent and concentration-dependent manner through induction of apoptosis. The level of long noncoding RNA cancer susceptibility candidate 2 (CASC2) and PTEN expression was upregulated by the ginsenoside Rg3 treatment, and CASC2/PTEN signaling was involved in the ginsenoside Rg3-induced cell growth suppression and apoptosis in GEM-resistant pancreatic cancer cells. Ginsenoside Rg3 could be an effective anticancer agent for chemoresistant pancreatic cancer.

The role of long non-coding RNA CASC2 in the carcinogenesis process

The lncRNA cancer susceptibility candidate 2 (CASC2) has been initially discovered in a genomic area on 10q26 that is commonly lost in human endometrial cancer. Subsequent assessments revealed its down-regulation in almost all kinds of cancer including glioma, breast cancer, colorectal cancer, lung cancer, ovarian cancer and hepatocellular carcinoma. Yet, it has been shown to be up-regulated in astrocytoma and in paclitaxel (PTX) resistant breast cancer tissues. In vitro studies have shown the role of this lncRNA in suppression of cell proliferation and induction of apoptosis. Animal studies have shown that over-expression of CASC2 suppresses tumorigenesis of human cancer cells in xenograft models. Diagnostic power of CASC2 levels has been evaluated in a number of human cancers and the best parameters have been demonstrated in pituitary adenomas and oral squamous cell carcinoma. Taken together, the main body of evidence show a tumor suppressor role of CASC2 and indicate up-regulation of this lncRNA as a putative therapeutic modality for human cancers. In this review, we summarize the data regarding expression pattern, function and diagnostic role of CASC2 in human cancer based on the results of cell line studies, animal investigations and human studies.

LncRNA CASC2 inhibits hypoxia-induced pulmonary artery smooth muscle cell proliferation and migration by regulating the miR-222/ING5 axis

Background

Pulmonary arterial hypertension (PAH) is often characterized by cell proliferation and migration of pulmonary arterial smooth muscle cells (PASMCs). LncRNA cancer susceptibility candidate 2 (CASC2) has been revealed to be involved in PASMC injury in hypoxia-induced pulmonary hypertension. However, the exact molecular mechanisms whereby CASC2 regulates PASMC proliferation and migration are still incompletely understood.

Methods

The expression levels of CASC2, miR-222 and inhibitor of growth 5 (ING5) were measured using quantitative real-time polymerase chain reaction (qRT-PCR) or western blot, respectively. Cell proliferation was analyzed by Cell Counting Kit-8 (CCK-8) assay. Wound healing assay was used to analyze cell migration ability. The relationship between miR-222 and CASC2 or ING5 was confirmed using bioinformatics analysis, luciferase reporter assay and RNA immunoprecipitation assay.

Results

CASC2 was down-regulated in hypoxia-induced PASMCs in a dose- and time-dependent manner. Functional experiments showed that CASC2 overexpression could reverse hypoxia-induced proliferation and migration of PASMCs. Bioinformatics analysis indicated that CASC2 acted as a competing endogenous RNA of miR-222, thereby regulating the expression of ING5, the downstream target of miR-222, in PASMCs. In addition, rescue assay suggested that the inhibition mediated by CASC2 of hypoxia-induced PASMC proliferation and migration could be attenuated by miR-222 inhibition or ING5 overexpression.

Conclusion

CASC2 attenuated hypoxia-induced PASMC proliferation and migration by regulating the miR-222/ING5 axis to prevent vascular remodeling and the development of PAH, providing a novel insight and therapeutic strategy for hypoxia-induced PAH.

[Musashi-1 positively regulates growth and proliferation of hepatoma cells in vitro]

OBJECTIVE

To investigate the regulatory role of Musashi-1 (MSI1) in the proliferation and growth of hepatocellular carcinoma (HCC) cells.

METHODS

We examined the expression of MSI1 in HCC and paired adjacent tissues from 24 patients using immunohistochemistry and Western blotting. A MSI1-expressing vector was constructed and stably transfected into HepG2 cells, and short hairpin RNAs (shRNAs) that targeted MSI1 mRNA were ligated into the vector and stably transfected in Huh7 cells. The effects of MSI1 overexpression and silencing on the proliferation, viability and cell cycle of HepG2 cells were investigated using flow cytometry or MTT assay. The expressions of PCNA, cyclin D1, APC and β-catenin in the HCC cells were detected with Western blotting.

RESULTS

MSI1 expression was significantly up-regulated in HCC tissues as compared with that in the adjacent tissues. Overexpression of MSI1 in HepG2 cells resulted in significantly enhanced cell growth (P < 0.01) and significantly reduced G0/G1 phase cells from (58.42±3.18)% to (40.67±1.22)% and increased S phase cells from (28.51± 1.93)% to (40.06±1.92)% (P < 0.01), causing also increases in the expressions of PCNA and Cyclin D1. Knockdown of MSI1 in Huh7 cells obviously inhibited the cell growth and caused cell cycle arrest at the G1/S phase (P < 0.01) with reduced protein expressions of PCNA and cyclin D1. Overexpression of MSI1 in HepG2 cells also down-regulated the expression of APC and up-regulated the expression of β-catenin protein, while MSI1 knockdown caused reverse changes in Huh7 cells.

CONCLUSIONS

MSI1 promotes the progression of HCC through positive modulation of cell growth and cell cycle via the Wnt/β-catenin pathway.

Long non-coding RNAs (CASC2 and TUG1) in hepatocellular carcinoma: Clinical significance

BACKGROUND

The biology of hepatocellular carcinoma remains poorly understood. Long non-coding RNAs (lncRNAs) have been confirmed to be key regulators of most cell processes and cancer. The lncRNA cancer susceptibility candidate 2 (CASC2) was originally identified as a downregulated gene in endometrial cancer and acted as a tumor suppressor. The lncRNA taurine up-regulated gene 1 (TUG1) has been shown to play an oncogenic role in various cancers. However, the relative expression of CASC2 and TUG1 in hepatocellular carcinoma (HCC) on top of hepatitis C virus (HCV) and the relationship between both remains unclear. The present study aimed to evaluate both lncRNA CASC2 and TUG1 relative gene expression in whole blood of HCC/HCV patients in relation to HCV and healthy subjects and to relate them to each other and to different clinicopathological factors.

METHODS

The relative expression of CASC2 and TUG1 was estimated by a quantitative reverse transcriptase-polymerase chain reaction in 30 HCC/HCV patients and compared with 20 cases of HCV patients and 20 controls.

RESULTS

CASC2 was downregulated in HCC/HCV patients, whereas TUG1 was overexpressed in relation to HCV and the control group, indicating their antagonistic effect. This suggests their role in the pathogenesis of HCC on top of HCV. Their expression was correlated to Barcelona Clinic Liver Cancer stage and serum alpha-fetoprotein level.

CONCLUSIONS

CASC2 and TUG1 could be new potential biomarkers with a valid non-invasive technique.

Long non-coding RNA CASC2 serves as a ceRNA of microRNA-21 to promote PDCD4 expression in oral squamous cell carcinoma

Background: Oral squamous cell carcinoma (OSCC) is a common oral disease with high morbidity and mortality. Recently, long non-coding RNAs (lncRNAs) were identified as critical regulators in OSCC tumorigenesis. The present study aimed to work out the functions and the possible molecular mechanisms of lncRNA CASC2 in human OSCC. Methods: The expression levels of CASC2 in clinical OSCC tissue samples and cultured OSCC cell lines were detected by RT-qPCR analysis. MTT assay was performed to detect the proliferation ability of OSCC cells, whereas the apoptosis rate and cell cycle distribution of OSCC cells were determined by flow cytometric analysis. The expression levels of relevant proteins were detected by Western blot assay. Dual-luciferase reporter assay was performed to validate the predicted relationship between CASC2, miR-21 amd PDCD4. The role of CASC2 in OSCC tumorigenesis in vivo was evaluated using a nude mouse tumor model. Results: The results demonstrated that CASC2 was significantly downregulated in clinical OSCC tissue samples and cultured OSCC cell lines. Low CASC2 expression was closely correlated with adverse clinicopathological characteristics of OSCC patients. Functionally, overexpression of CASC2 remarkably inhibited cell proliferation partly through inducing cell cycle arrest and cell apoptosis. Furthermore, bioinformatics analysis and dual-luciferase reporter assay showed that CASC2 might act as a competing endogenous RNA of miR-21 to promote the expression of PDCD4. Rescue experiments also showed that miR-21 blocked the tumor-suppressive role that CASC2 exerted in OSCC cells. Finally, in vivo study indicated that overexpression of CASC2 restrained OSCC tumor growth in volume and weight. Conclusion: In conclusion, these findings indicate that CASC2/miR-21/PDCD4 axis might be a potential regulator of OSCC tumorigenesis, and shed new light on lncRNA-directed diagnostics and therapeutics in OSCC.