Down-regulation of LncRNA TUG1 enhances radiosensitivity in bladder cancer via suppressing HMGB1 expression

LncRNA TUG1 promotes cisplatin resistance in esophageal squamous cell carcinoma cells by regulating Nrf2

Esophageal squamous cell carcinoma (ESCC) is a common malignancy with poor prognosis. The drug resistance compromises the efficacy of chemotherapy for ESCC. Long non-coding RNA taurine upregulated gene 1 (TUG1) has been identified as a promoter of cancer progression and chemotherapy resistance in many malignancies. However, the exact role of TUG1 in ESCC chemotherapy resistance remains unclear. In this study, we showed that TUG1 expression in TE-1-derived cisplatin (DDP)-resistant (TE-1/DDP) cells was higher than that in TE-1 cells. Furthermore, TUG1 promoted DDP resistance in TE-1 and TE-1/DDP cells by promoting cell proliferation, suppressing cell apoptosis, and elevating protein expression of the classical multi-drug resistance-related P-gp. In contrast, TUG1 knockdown exerted an opposite effect. Mechanistically, RNA pull-down and RNA immunoprecipitation assays confirmed that TUG1 directly bound to nuclear factor (erythroid-derived 2)-like 2 (Nrf2) protein and elevated Nrf2 protein expression. Moreover, Nrf2-neutralizing antibody effectively reversed the TUG1 overexpression-mediated promotion of ESCC cell resistance to DDP. In conclusion, our findings demonstrated that TUG1 promoted ESCC cell resistance to DDP, at least in part, through upregulating Nrf2.

Transcription factor Nrf2 induces the up-regulation of lncRNA TUG1 to promote progression and adriamycin resistance in urothelial carcinoma of the bladder

Background

Taurine-upregulated gene 1 (TUG1) has been documented to be implicated in carcinogenesis and chemoresistance in solid tumors. Here, we explored the biological role and regulatory mechanism of TUG1 in progression and chemoresistance of urothelial carcinoma of the bladder (UCB).

Methods

Nuclear factor-erythroid 2 (NF-E2)-related factor 2 (Nrf2) mRNA and TUG1 expression was determined by quantitative reverse transcription polymerase chain reaction. Western blot was performed to determine the protein levels of Nrf2, p-glycoprotein (p-gp), Ki-67 (Ki67), matrix metalloproteinase (MMP)-2 and MMP-9 and cleaved caspase-3. The effects of either Nrf2 or TUG1 knockdown on the proliferation, invasion, apoptosis and adriamycin (ADM) resistance of UCB cells were evaluated by CCK-8 assay, transwell invasion assay and flow cytometry analysis. Xenograft tumor assay was carried out to confirm the role of Nrf2 and TUG1 in ADM resistance of UCB cells in vivo.

Results

Nrf2 and TUG1 were upregulated in UCB tissues and cell lines. A positive correlation between Nrf2 and TUG1 expression was discovered in UCB tissues. Moreover, Nrf2 and TUG1 expression levels were higher in ADM-resistant cells compared with those in parental cells. Furthermore, Nrf2 positively regulated the expression of TUG1 in UCB cells. Knockdown of either Nrf2 or TUG1 led to the inhibition of cell proliferation and invasion and promotion of cell apoptosis, accompanying with down-regulation of Ki67, MMP-2 and MMP-9 and up-regulation of cleaved caspase-3. Knockdown of either Nrf2 or TUG1 enhanced the sensitivity of BIU-87/ADM and T24/ADM cells to ADM, as indicated by decreased expression of p-gp. Besides, knockdown of either Nrf2 or TUG1 inhibited tumor growth in the absence or presence of ADM in vivo.

Conclusions

Nrf2 induces the up-regulation of TUG1 to promote progression and ADM resistance in UCB.

Long Non-coding Ribonucleic Acid as a Novel Diagnosis and Prognosis Biomarker of Bladder Cancer

Long non-coding ribonucleic acids (lncRNAs) are the largest group of non-coding RNAs and supposedly have a broad spectrum of diverse functions in normal cellular processes. This study was carried out to review the biological functions of candidate lncRNAs (i.e., H19, MALAT-1, TUG1, UCA-1, MEG-3, HOTAIR, CCAT2, AATBC, and the like) with aberrant expressions that play critical roles in bladder cancer (BC) initiation, progression, and metastasis. A formal narrative review was performed by searching the PubMed database for English articles using a combination of keywords such as "long non-coding RNA", "lncRNA", "cancer", "bladder cancer", "screening", "prognosis", "diagnosis", and "response to therapy". In addition, the existing literature was studied on biological function, aberrant expression, and the clinical applications of candidate lncRNAs in BC. By a better understanding of the molecular mechanisms of lncRNAs, they can be used as biomarkers for tumor signatures in urologic malignancies, which can improve screening, prognosis, diagnosis, and the treatment of BC.

Knockdown of LINC00511 promotes radiosensitivity of thyroid carcinoma cells via suppressing JAK2/STAT3 signaling pathway

Thyroid carcinoma is the most widespread malignancy in endocrine system with the increasing incidence. Despite of the advanced approaches to the management of thyroid carcinoma, the therapeutic effects remain unpleasant largely due to the radiosensitivity of thyroid carcinoma cells. LncRNAs play important part in the tumorigenesis and development, especially in the radiosensitivity of tumor cells. However, their roles in thyroid carcinoma still needed to be explored deeply. The purpose of our research is to inspect the possible biological role and regulation mechanism of LINC00511 desirable for therapies of thyroid carcinoma patients. In the present study, LINC00511 was significantly overexpressed in thyroid carcinoma and its silencing boosted radiosensitivity of thyroid carcinoma cells. Then we unveiled that LINC00511 regulated JAK2/STAT3 signaling pathway which was resistant to radiation treatment. Besides, TAF1 modulated JAK2 at transcriptional level. Moreover, LINC00511 bound to TAF1 and further promoted JAK2 expression. In conclusion, rescue experiments verified that the radiosensitivity of thyroid carcinoma cells was attributed to LINC00511/TAF1/JAK2/STAT3 axis. The current paper investigated the underlying mechanism of LINC00511 and set a new therapeutic direction for the therapy of thyroid carcinoma.

Expression analysis of a panel of long non-coding RNAs (lncRNAs) revealed their potential as diagnostic biomarkers in bladder cancer

INTRODUCTION

Long non-coding RNAs (lncRNAs) have fundamental roles in cell migration, proliferation, invasion and metastasis.

METHODS

In the current study, we evaluated expression of a panel of lncRNAs in bladder cancer tissues, adjacent non-cancerous tissues (ANCTs) and normal bladder tissues to evaluate their diagnostic power.

RESULTS

PV1 was down-regulated in tumor tissues compared with both ANCTs and normal controls (Expression ratios of 0.48 and 0.14; P values of 0.4 and <0.001 respectively). HOTAIR, NEAT1, TUG1 and FAS-AS1 were significantly down-regulated in tumor tissues compared with normal controls (Expression ratios of 0.4, 0.68, 0.54 and 0.11; P values of 0.04, 0.02, 0.02 and <0.001 respectively).

CONCLUSION

Combination of transcript levels of seven lncRNAs improved both sensitivity and specificity values to 100%. The current study shows dysregulation of lncRNAs in bladder cancer and implies their role as diagnostic markers in this malignancy.

The immune mediated role of extracellular HMGB1 in a heterotopic model of bladder cancer radioresistance

Radical cystectomy (RC) together with bilateral pelvic lymph node dissection remains the standard treatment for muscle invasive bladder cancer (MIBC). However, radiation-based treatments such as tri-modal therapy (TMT) involving maximally performed transurethral resection of bladder tumor (TURBT), radiotherapy (XRT), and a chemosensitizer represent an attractive, less invasive alternative. Nevertheless, 25–30% of MIBC patients will experience local recurrence after TMT and half will develop metastasis. Radioresistance of tumor cells could potentially be one of the causes for local recurrence post treatment. High mobility group box-1 (HMGB1) was shown to play a role in bladder cancer radioresistance through its intracellular functions in promoting DNA damage repair and autophagy. Recently, HMGB1 was found to be passively released from irradiated tumor cells. However, less is known about the involvement of extracellular HMGB1 in impairing radiation response and its exact role in modulating the tumor immune microenvironment after XRT. We identified a novel mechanism of bladder cancer radioresistance mediated by the immunological functions of HMGB1. The combination of radiation plus extracellular HMGB1 inhibition markedly improved the radiation response of tumors and resulted in marked changes in the immune landscape. Moreover, combining radiation and HMGB1 inhibition significantly impaired tumor infiltrating MDSCs and TAMs -but not Tregs- and shifted the overall tumor immune balance towards anti-tumoral response. We conclude that extracellular HMGB1 is involved in bladder cancer radioresistance through promoting pro-tumor immune mechanisms.

High-mobility group box 1 protein modulated proliferation and radioresistance in esophageal squamous cell carcinoma

BACKGROUND AND AIM

The high-mobility group box 1 (HMGB1) protein plays an important role in a lot of biological behaviors, including DNA damage repair, gene transcription, cell replication, and cell death, and its expression is higher in many solid tumors tissues than in their adjacent normal tissues, and it is always involved in tumor proliferation, metastasis, therapeutic tolerance, and poor prognosis. However, HMGB1 in proliferation and radioresistance of esophageal squamous cell carcinoma (ESCC) remains poorly understood. In this study, the effect of HMGB1 on proliferation, cell death, DNA damage repair and radioresistance, and its underlying mechanism was investigated in human ESCC.

METHODS

The immunohistochemistry scores of tumor and adjacent normal tissues in ESCC tissue microarray were analyzed. Stable HMGB1 knockdown cell lines were constructed using Kyse150 and Kyse450 cells. Cell viability, radioresistance, apoptosis, autophagy, and DNA damage were determined using CCK-8, 5-ethynyl-2'-deoxyuridine, clonogenic survival assay, immunofluorescence, flow cytometry, and western blot assays.

RESULTS

Differential analyses showed that the expression of HMGB1 in esophageal cancer tissue was significantly higher than that in adjacent normal tissues. The downregulation of HMGB1 could effectively inhibit proliferation, increase radiosensitivity, impair DNA damage repair abilities, reduce autophagy, and increase apoptosis rates in ESCC cells after irradiation.

CONCLUSIONS

HMGB1 is expected to be a potential target for ESCC therapy and radiosensitization.

Taurine-upregulated gene 1: A functional long noncoding RNA in tumorigenesis

Taurine-upregulated gene 1 (TUG1) is a 7.1 kb long noncoding RNA (lncRNA) first recognized in 2005 as an important element for retinal development in rodents. Subsequently, this lncRNA has been shown to participate in oncogenic processes through alteration in chromatin structure, sponging microRNAs, and affecting the expression of some cancer-related pathways. While most of the studies have revealed an oncogenic role for this lncRNA, some reports have shown downregulation of TUG1 in lung cancer samples compared with noncancerous samples. In triple negative breast cancer samples, the expression of this lncRNA has been decreased. Besides, its expression has been higher in HER2-enriched and basal-like subtypes compared with luminal A. In the current review, we discuss the latest literature about the expression pattern and functional roles of TUG1 in diverse cancer types. In addition, its role in epithelial-mesenchymal transition and activation of Wnt/β-catenin pathway in human malignancies will be explored.

Taurine-upregulated gene 1 contributes to cancers through sponging microRNA

Long non-coding RNAs (lncRNAs) are a class of RNAs whose transcripts are more than 200 nucleotides in length and lack protein-coding ability. Taurine-upregulated gene 1 (TUG1), a novel cancer-related lncRNA, has been documented to be abnormally expressed in various types of cancers and act as an oncogene or anti-oncogene. It has been considered previously that TUG1 is closely related to the cell proliferation, invasion, metastasis, and apoptosis of cancer. In recent years, it has been found that TUG1 acts as a microRNA (miRNA) sponge to indirectly regulate the expression of the miRNA target gene and dominates cancer progression in several types of cancers. However, TUG1 also binds to different miRNAs to produce diverse regulatory mechanisms in the same cancer. TUG1 is expected to be a biomarker and a new therapeutic target for the diagnosis and prognosis of certain cancers. In this review, we highlight the up-to-date original studies that focus on the role of TUG1 sponging miRNA in cancers and summarize the function of TUG1 in cancer progression. The novel TUG1-miRNA regulatory network is comprehensively and minutely included in this review. We hope that this review will help readers obtain a more detailed knowledge of the molecular mechanism by which TUG1 sponging miRNA plays its role in cancers, and provide some insights and directions for future cancer research.

Long non-coding RNA TUG1 recruits miR‑29c‑3p from its target gene RGS1 to promote proliferation and metastasis of melanoma cells

Melanoma is an aggressive type of skin cancer, characterized by high mortality rates worldwide. Therefore, the identification of new diagnostic markers and therapeutic targets for melanoma is imperative. Accumulating evidence has demonstrated that long non-coding RNAs (lncRNAs) play important roles in tumor initiation and progression. It was recently reported that the expression of lncRNA taurine upregulated 1 (TUG1) was relatively higher in cancer compared with that in normal cells, and that TUG1 promoted the progression of various cancers. However, the pattern of expression and mechanism of action of TUG1 in melanoma remain unclear. The aim of the present study was to investigate whether TUG1 expression is relatively higher in melanoma tissues and whether this expression is correlated with poor overall survival. Knockdown of TUG1 was found to suppress melanoma cell growth and metastasis and induce cell apoptosis. By contrast, the overexpression of TUG1 promoted the growth and metastasis of melanoma cells, and inhibited their apoptosis. In addition, the results of the present study indicated that TUG1 sequestered endogenous miR‑29c‑3p and that it was able to suppress its expression. Furthermore, it was observed that miR‑29c‑3p could reverse the promoting effect of TUG1 on melanoma progression, which may be associated with the positive regulation of regulator of G-protein signaling 1 (RGS1), a target gene of miR‑29c‑3p. Taken together, the data of the present study demonstrated that TUG1 promoted proliferation and invasion and suppressed apoptosis in melanoma cells by regulating miR‑29c‑3p and its target gene, RGS1. Therefore, lncRNA TUG1 appears to be a promising diagnostic marker for melanoma patients.

LncRNA GAS5 confers the radio sensitivity of cervical cancer cells via regulating miR-106b/IER3 axis

OBJECTIVE

The aim of the study was to investigate the biological role of growth arrest special 5 (GAS5) in the radio sensitivity of cervical cancer (CC).

METHODS

The expressions of GAS5, miR-106b and immediate early response 3 (IER3) were detected in CC tissues and CC cell lines. RNA immunoprecipitation and RNA pull-down assays were performed to test the interaction of GAS5 and miR-106b. Dual-luciferase reporter assay was used to detect the regulatory relationship between miR-106b and IER3. The nude mouse model of CC was established for verifying the effects of GAS5 on the resistance of CC to radiation therapy in vivo.

RESULTS

GAS5 and IER3 were low expressed in the radio-resistant human CC tissues and SiHa cells, while miR-106b expression was highly expressed. Overexpression of IER3 or GAS5 enhanced radio-sensitivity in SiHa cells, while knockdown of IER3 or GAS5 decreased radio-sensitivity in ME180 cells. Moreover, GAS5 served as a miR-106b sponge, and miR-106b negatively regulated IER3 expression. Besides, GAS5 could regulate IER3 expression through miR-106b, and GAS5 enhanced the radio-sensitivity in CC cells through inhibiting miR-106b both in vitro and in vivo.

CONCLUSION

Overexpression of GAS5 enhanced the sensitivity of CC cells to radiation treatment via up-regulating IER3 through miR-106b.

Long noncoding RNAs as biotargets in cisplatin-based drug resistance

Since its discovery, cisplatin has become the key drug in chemotherapy for cancers. Nevertheless, chemoresistance in cancers has become an impediment in using cisplatin for cancer treatment. The resistance toward cisplatin is multifaceted as it involves multiple cellular pathways. Ever since the knowledge of long noncoding RNAs as modulators of various molecular pathways came to light, the interest in the biological function of lncRNAs as biomarkers has increased dramatically. Numerous studies have reported the link between the dysregulation of lncRNAs and drug resistance in cancers. More importantly, several lncRNAs were found to be vital in regulating cisplatin resistance. Therefore, this review summarizes the recent efforts in linking between cisplatin resistance and different types of lncRNAs.

Data mining of the cancer-related lncRNAs GO terms and KEGG pathways by using mRMR method

LncRNAs plays an important role in the regulation of gene expression. Identification of cancer-related lncRNAs GO terms and KEGG pathways is great helpful for revealing cancer-related functional biological processes. Therefore, in this study, we proposed a computational method to identify novel cancer-related lncRNAs GO terms and KEGG pathways. By using existing lncRNA database and Max-relevance Min-redundancy (mRMR) method, GO terms and KEGG pathways were evaluated based on their importance on distinguishing cancer-related and non-cancer-related lncRNAs. Finally, GO terms and KEGG pathways with high importance were presented and analyzed. Our literature reviewing showed that the top 10 ranked GO terms and pathways were really related to interpretable tumorigenesis according to recent publications.

Long non‑coding RNA urothelial cancer associated 1 regulates radioresistance via the hexokinase 2/glycolytic pathway in cervical cancer

Cervical cancer is one of the most common types of female malignant tumor. It is well established that radiotherapy (RT) is the first‑line treatment of cervical cancer; however, radioresistance is a substantial obstacle to cervical cancer RT. At present, the mechanism underlying radioresistance remains unclear. Emerging evidence has demonstrated that long non‑coding RNAs (lncRNAs) function as crucial regulators of diverse cancers. Aerobic glycolysis, which is a common phenomenon in cancer cells, is associated with various biological functions, including radioresistance. To the best of our knowledge, the present study is the first to explore the role of the lncRNA urothelial cancer associated 1 (UCA1) in cervical cancer radioresistance. In the present study, irradiation was used to establish irradiation‑resistant (IRR) cells, after which a clonogenic survival assay was used to validate radioresistance, reverse transcription‑quantitative polymerase chain reaction was used to evaluate the expression levels of UCA1 and western blotting was conducted to detect the expression levels of glycolysis‑related proteins. In addition, a glucose/lactate assay kit was used to evaluate glucose/lactate concentrations and cells were transfected with small interfering RNA/pcDNA to regulate the expression of UCA1. Following the establishment of IRR cell lines (SiHa‑IRR and HeLa‑IRR), it was demonstrated that SiHa‑IRR and HeLa‑IRR cells exhibited increased expression levels of UCA1 and enhanced glycolysis. Dysregulation of UCA1 and inhibition of glycolysis affected radioresistance of cervical cancer cells. In addition, the results indicated that UCA1 promoted radioresistance‑associated glycolysis in SiHa‑IRR and HeLa‑IRR cells, with the enzyme hexokinase 2 (HK2) acting as a significant regulator in this process. Inhibiting glycolysis by 2‑DG reversed the effects of UCA1 overexpression on HK2 protein expression and radioresistance in SiHa and HeLa cells. Taken together, these findings suggested that UCA1 may have an important role in regulating radioresistance through the HK2/glycolytic pathway, providing novel potential targets to improve cervical cancer RT.

Knockdown of SUMO1P3 represses tumor growth and invasion and enhances radiosensitivity in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most common types of malignant tumors with high recurrence and metastasis rates. Radiotherapy represents a major therapeutic option for HCC patients. However, the efficacy of radiotherapy has been limited due to the development of intrinsic radioresistance of the tumor cells. Small ubiquitin-like modifier 1 pseudogene 3 (SUMO1P3), one member of SUMO pseudogene family, is a novel identified lncRNA that was originally identified to be upregulated in gastric cancer. However, the detailed roles of SUMO1P3 in HCC development remain to be elucidated. Here, the expression of SUMO1P3 in HCC tissues and cells was examined by qRT-PCR. Cell proliferation, colony formation ability, invasion ability, apoptosis, and radiosensitivity were detected by MTT assay, colony formation assay, cell invasion assay, flow cytometry analysis, and survival fraction assay, respectively. We found that SUMO1P3 was significantly upregulated in HCC tissues and cells. Besides, SUMO1P3 was highly expressed in HCC patients with higher TNM stage. Furthermore, SUMO1P3 knockdown markedly suppressed cell proliferation, colony formation ability, and cell invasiveness, promoted apoptosis, and enhanced radiosensitivity of HCC cells. We concluded that the knockdown of SUMO1P3 repressed tumor growth, invasion, promoted apoptosis, and enhanced radiosensitivity in HCC, providing evidence that SUMO1P3 might be a potential novel biomarker and a therapeutic target for HCC.

The use of long non-coding RNAs as prognostic biomarkers and therapeutic targets in prostate cancer

Prostate cancer is the most common cancer in men and the second leading cause of cancer-related deaths. The most used biomarker to detect prostate cancer is Prostate Specific Antigen (PSA), whose levels are measured in serum. However, it has been recently established that molecular markers of cancer should not be based solely on genes and proteins but should also reflect other genomic traits; long non-coding RNAs (lncRNAs) serve this purpose. lncRNAs are transcripts of >200 bases that do not encode proteins and that have been shown to display abnormal expression profiles in different types of cancer. Experimental studies have highlighted lncRNAs as potential biomarkers for prognoses and treatments in patients with different types of cancer, including prostate cancer, where the PCA3 lncRNA is currently used as a diagnostic tool and management strategy. With the development of genomic technologies, particularly next-generation sequencing (NGS), several other lncRNAs have been linked to prostate cancer and are currently under validation for their medical use. In this review, we will discuss different strategies for the discovery of novel lncRNAs that can be evaluated as prognostic biomarkers, the clinical impact of these lncRNAs and how lncRNAs can be used as potential therapeutic targets.

Molecular mechanisms of long noncoding RNAs and their role in disease pathogenesis

LncRNAs are long non-coding regulatory RNAs that are longer than 200 nucleotides. One of the major functions of lncRNAs is the regulation of specific gene expression at multiple steps including, recruitment and expression of basal transcription machinery, post-transcriptional modifications and epigenetics [1]. Emerging evidence suggests that lncRNAs also play a critical role in maintaining tissue homeostasis during physiological and pathological conditions, lipid homeostasis, as well as epithelial and smooth muscle cell homeostasis, a topic that has been elegantly reviewed [2-5]. While aberrant expression of lncRNAs has been implicated in several disease conditions, there is paucity of information about their contribution to the etiology of diseases [6]. Several studies have compared the expression of lncRNAs under normal and cancerous conditions and found differential expression of several lncRNAs, suggesting thereby an involvement of lncRNAs in disease processes [7, 8]. Furthermore, the ability of lncRNAs to influence epigenetic changes also underlies their role in disease pathogenesis since epigenetic regulation is known to play a critical role in many human diseases [1]. LncRNAs thus are not only involved in homeostatic functioning but also play a vital role in the progression of many diseases, thereby underscoring their potential as novel therapeutic targets for the alleviation of a variety of human disease conditions.

Radiation-Induced Long Noncoding RNAs in a Mouse Model after Whole-Body Irradiation

Long noncoding RNAs (lncRNAs) are emerging as key molecules in regulating many biological processes and have been implicated in development and disease pathogenesis. Biomarkers of cancer and normal tissue response to treatment are of great interest in precision medicine, as well as in public health and medical management, such as for assessment of radiation injury after an accidental or intentional exposure. Circulating and functional RNAs, including microRNAs (miRNAs) and lncRNAs, in whole blood and other body fluids are potential valuable candidates as biomarkers. Early prediction of possible acute, intermediate and delayed effects of radiation exposure enables timely therapeutic interventions. To address whether long noncoding RNAs (lncRNAs) could serve as biomarkers for radiation biodosimetry we performed whole genome transcriptome analysis in a mouse model after whole-body irradiation. Differential lncRNA expression patterns were evaluated at 16, 24 and 48 h postirradiation in total RNA isolated from whole blood of mice exposed to 1, 2, 4, 8 and 12 Gy of X rays. Sham-irradiated animals served as controls. Significant alterations in the expression patterns of lncRNAs were observed after different radiation doses at the various time points. We identified several radiation-induced lncRNAs known for DNA damage response as well as immune response. Long noncoding RNA targets of tumor protein 53 (P53), Trp53cor1, Dino, Pvt1 and Tug1 and an upstream regulator of p53, Meg3, were altered in response to radiation. Gm14005 ( Morrbid) and Tmevpg1 were regulated by radiation across all time points and doses. These two lncRNAs have important potential as blood-based radiation biomarkers; Gm14005 ( Morrbid) has recently been shown to play a key role in inflammatory response, while Tmevpg1 has been implicated in the regulation of interferon gamma. Precise molecular biomarkers, likely involving a diverse group of inducible molecules, will not only enable the development and effective use of medical countermeasures but may also be used to detect and circumvent or mitigate normal tissue injury in cancer radiotherapy.

Long Noncoding RNA ATB Promotes Proliferation, Migration, and Invasion in Bladder Cancer by Suppressing MicroRNA-126

This study aimed to explore the biological functions of long noncoding RNA activated by transforming growth factor-β (lncRNA-ATB) in bladder cancer cells. For the expressions of lncRNA-ATB, miR-126, and KRAS, T24 cells were transfected with their specific vectors/shRNA or mimic/inhibitor. Then cell viability, migration, invasion, and apoptosis as well as the protein levels of apoptosis-related factors and PI3K/AKT and mTOR signal pathways were measured. The relationships of lncRNA-ATB and miR-126 or miR-126 and KRAS were analyzed by Dual-Luciferase Reporter assay. Functional experiments showed that lncRNA-ATB overexpression significantly promoted cell viability, migration, and invasion in T24 cells. lncRNA-ATB was a molecular sponge of miR-126 and exerted tumor-promoting effects by downregulation of miR-126. Moreover, KRAS was a direct target of miR-126 and was negatively regulated by miR-126. Finally, overexpression of KRAS increased cell viability, migration, and invasion, as well as activated PI3K/AKT and mTOR signaling pathways in T24 cells. The results revealed that lncRNA-ATB was an oncogene, which promoted cell proliferation, migration, and invasion by regulating miR-126 in bladder cancer. These findings may provide a potential prognostic biomarker and a therapeutic target for bladder cancer.

mRNA, microRNA and lncRNA as novel bladder tumor markers

Early detection of bladder cancer (BC) is essential for improvement of the patient's prognosis and general survival rates. Current diagnostic methods are still limited, so new specific and cost-effective biomarkers are emerging as the noninvasive tools in treatment decisions in recurrent BC. Gene expression and epigenetic profile can be analysed using quantitative real-time-PCR (qRT-PCR) method in urine, blood and tissue. This review provides an update of recent findings on BC molecular profile as novel markers in diagnosis and prognosis of bladder tumors. We describe mRNA-, microRNA- and lncRNA-based biomarkers involved in the BC detection, diagnosis, prediction of recurrence and monitoring after treatment.

Differential radiation response between normal astrocytes and glioma cells revealed by comparative transcriptome analysis

Normal astrocytes are more resistant to radiation than glioma cells. Radiation-resistant glioma cells and normal astrocytes usuallly share similar mechanisms of radioresistance. Investigation of the underlying mechanisms of differential radiation response between normal astrocytes and glioma cells is thus significant for improvement of glioma treatment. Here, we report on the differential radiation responses between normal astrocytes and glioma cells at the transcriptome level. Human astrocytes (HA) and U251 glioma cell lines were used as in vitro models. The transcriptome profiles of radiation-treated and nontreated HA and U251 cells were generated by next-generation sequencing. In total, 296 mRNAs and 224 lncRNAs in HA and 201 mRNAs and 107 lncRNAs in U251 were found to be differentially expressed after radiation treatment. Bioinformatics analyses indicated that radiation causes similar alterations in HA and U251 cells, while several key pathways involved in cancer development and radiation resistance, including P53, TGF-β, VEGF, Hippo and serotonergic synapse pathways, were oppositely regulated by radiation treatment, suggesting their important role in this process. Furthermore, we showed the critical role of Hippo/YAP signaling in radiation resistance of glioma cells. In summary, our findings revealed novel insights about differential responses between normal astrocytes and glioma cells. Our work suggested that YAP inhibitor could not be used in combination with radiation for glioma treatment.

Roles of Long Noncoding RNAs in Recurrence and Metastasis of Radiotherapy-Resistant Cancer Stem Cells

Radiotherapy is a well-established therapeutic regimen applied to treat at least half of all cancer patients worldwide. Radioresistance of cancers or failure to treat certain tumor types with radiation is associated with enhanced local invasion, metastasis and poor prognosis. Elucidation of the biological characteristics underlying radioresistance is therefore critical to ensure the development of effective strategies to resolve this issue, which remains an urgent medical problem. Cancer stem cells (CSCs) comprise a small population of tumor cells that constitute the origin of most cancer cell types. CSCs are virtually resistant to radiotherapy, and consequently contribute to recurrence and disease progression. Metastasis is an increasing problem in resistance to cancer radiotherapy and closely associated with the morbidity and mortality rates of several cancer types. Accumulating evidence has demonstrated that radiation induces epithelial–mesenchymal transition (EMT) accompanied by increased cancer recurrence, metastasis and CSC generation. CSCs are believed to serve as the basis of metastasis. Previous studies indicate that CSCs contribute to the generation of metastasis, either in a direct or indirect manner. Moreover, the heterogeneity of CSCs may be responsible for organ specificity and considerable complexity of metastases. Long noncoding RNAs (lncRNAs) are a class of noncoding molecules over 200 nucleotides in length involved in the initiation and progression of several cancer types. Recently, lncRNAs have attracted considerable attention as novel critical regulators of cancer progression and metastasis. In the current review, we have discussed lncRNA-mediated regulation of CSCs following radiotherapy, their association with tumor metastasis and significance in radioresistance of cancer.