LncRNA PANDAR regulates the G1/S transition of breast cancer cells by suppressing p16(INK4A) expression

Molecular mechanisms underlying the regulation of tumour suppressor genes in lung cancer

Tumour suppressor genes play a cardinal role in the development of a large array of human cancers, including lung cancer, which is one of the most frequently diagnosed cancers worldwide. Therefore, extensive studies have been committed to deciphering the underlying mechanisms of alterations of tumour suppressor genes in governing tumourigenesis, as well as resistance to cancer therapies. In spite of the encouraging clinical outcomes demonstrated by lung cancer patients on initial treatment, the subsequent unresponsiveness to first-line treatments manifested by virtually all the patients is inherently a contentious issue. In light of the aforementioned concerns, this review compiles the current knowledge on the molecular mechanisms of some of the tumour suppressor genes implicated in lung cancer that are either frequently mutated and/or are located on the chromosomal arms having high LOH rates (1p, 3p, 9p, 10q, 13q, and 17p). Our study identifies specific genomic loci prone to LOH, revealing a recurrent pattern in lung cancer cases. These loci, including 3p14.2 (FHIT), 9p21.3 (p16INK4a), 10q23 (PTEN), 17p13 (TP53), exhibit a higher susceptibility to LOH due to environmental factors such as exposure to DNA-damaging agents (carcinogens in cigarette smoke) and genetic factors such as chromosomal instability, genetic mutations, DNA replication errors, and genetic predisposition. Furthermore, this review summarizes the current treatment landscape and advancements for lung cancers, including the challenges and endeavours to overcome it. This review envisages inspired researchers to embark on a journey of discovery to add to the list of what was known in hopes of prompting the development of effective therapeutic strategies for lung cancer.

Metformin and long non-coding RNAs in breast cancer

Breast cancer (BC) is the second most common cancer and cause of death in women. In recent years many studies investigated the association of long non-coding RNAs (lncRNAs), as novel genetic factors, on BC risk, survival, clinical and pathological features. Recent studies also investigated the roles of metformin treatment as the firstline treatment for type 2 diabetes (T2D) played in lncRNAs expression/regulation or BC incidence, outcome, mortality and survival, separately. This comprehensive study aimed to review lncRNAs associated with BC features and identify metformin-regulated lncRNAs and their mechanisms of action on BC or other types of cancers. Finally, metformin affects BC by regulating five BC-associated lncRNAs including GAS5, HOTAIR, MALAT1, and H19, by several molecular mechanisms have been described in this review. In addition, metformin action on other types of cancers by regulating ten lncRNAs including AC006160.1, Loc100506691, lncRNA-AF085935, SNHG7, HULC, UCA1, H19, MALAT1, AFAP1-AS1, AC026904.1 is described.

Circulating LncRNAs landscape as potential biomarkers in breast cancer

BACKGROUND

In Iran, the delay in diagnosis and treatment of breast cancer results in low survival rates.

AIM

It is essential to characterize new therapeutic targets and prognostic breast cancer biomarkers. The rising evidence suggested that long non-coding RNAs (lncRNAs) expression levels are deregulated in human cancers and can use as biomarkers for the rapid diagnosis of breast cancer.

METHODS

In the present study, a quantitative real-time polymerase chain reaction (qRT-PCR) technique was used to measure 20 oncogenic and tumor suppressor lncRNAs expression levels in whole blood samples of female breast cancer patients and healthy women. Receiver operating characteristic curve (ROC) was used to assess the diagnostic value of each selected lncRNA as a biomarker.

RESULTS

The results revealed that some circulating lncRNAs (MEG3, NBAT1, NKILA, GAS5, EPB41L4A-AS2, Z38, and BC040587) were significantly down-regulated in breast cancer patients compared to healthy women. In contrast, other circulating lncRNAs (H19, SPRY4-IT1, XIST, UCA1, AC026904.1, CCAT1, CCAT2, ITGB2-AS, and AK058003) were significantly up-regulated in breast cancer patients compared to controls. It was shown that the expression levels of NKILA, and NBAT1 lncRNAs were related to tumor size, and BC040587 expression level related to age, node metastasis, tumor size, and grade (p < .05). The association between H19 and SPRY4-IT1 lncRNAs with HER-2 was confirmed statistically (p < .05). ROC curves illustrated that the blood levels of SPRY4-IT1, XIST, and H19 lncRNAs have excellent potential in discriminating breast cancer from the healthy controls, showing an AUC of 1.0 (95% CI 1.0-1.0, p = .00), 0.898 (95% CI 0.815-0.981, p = .00), and 0.848 (95% CI 0.701-0.995, p = .01), respectively.

CONCLUSION

In conclusion, the expression levels of circulating H19 and SPRY4-IT1 lncRNAs in breast cancer patients could consider as the prognostic biomarkers and therapeutic targets in breast cancer, because of their excellent power in discriminating breast cancer from healthy individuals and the significant correlation of H19, and SPRY4-IT1 lncRNAs with clinicopathological traits. We also suggest the possible application of BC040587 lncRNA as a diagnostic and prognostic indicator to assess tumor progression in case of verification in larger patients' cohorts.

The long non-coding RNA PANDAR regulates cell proliferation and epithelial-to-mesenchymal transition in glioma

Glioma is one of the most aggressive intracranial tumors in the central nervous system. The long non-coding RNA P21 associated ncRNA DNA damage activated (PANDAR) has been reported to be an oncogene or tumor suppressor in several cancers. However, the prognostic value and biological function of PANDAR in glioma have not been described. Here, we report that expression of PANDAR is significantly up-regulated in glioma tissues and cell lines. PANDAR expression was correlated with tumor size (p=0.044) and World Health Organization (WHO) grades (p=0.005), as shown by chi-squared test. Moreover, significant upregulation of PANDAR was found to correlate with poor prognosis in glioma, as shown using Kaplan-Meier method and Cox multivariate survival analysis. Furthermore, PANDAR knockdown suppressed cell proliferation, G1/S transition, migration and invasion, and promoted apoptosis in glioma cell lines (U251 and U87). PANDAR knockdown decreased expression of CDK4, Bcl-2, N-cadherin and Vimentin, but increased E-cadherin expression in glioma cells. In conclusion, our data suggest PANDAR as a potential prognostic biomarker and therapeutic candidate for glioma.

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.

Transcriptional regulation of INK4/ARF locus by cis and trans mechanisms

9p21 locus is one of the most reproducible regions in genome-wide association studies (GWAS). The region harbors CDKN2A/B genes that code for p16INK4a, p15INK4b, and p14ARF proteins, and it also harbors a long gene desert adjacent to these genes. The polymorphisms that are associated with several diseases and cancers are present in these genes and the gene desert region. These proteins are critical cell cycle regulators whose transcriptional dysregulation is strongly linked with cellular regeneration, stemness, aging, and cancers. Given the importance of this locus, intense scientific efforts on understanding the regulation of these genes via promoter-driven mechanisms and recently, via the distal regulatory mechanism have provided major insights. In this review, we describe these mechanisms and propose the ways by which this locus can be targeted in pathologies and aging.

The various regulatory functions of long noncoding RNAs in apoptosis, cell cycle, and cellular senescence

Long noncoding RNAs (lncRNAs) are a group of noncoding cellular RNAs involved in significant biological phenomena such as differentiation, cell development, genomic imprinting, adjusting the enzymatic activity, regulating chromosome conformation, apoptosis, cell cycle, and cellular senescence. The misregulation of lncRNAs interrupting normal biological processes has been implicated in tumor formation and metastasis, resulting in cancer. Apoptosis and cell cycle, two main biological phenomena, are highly conserved and intimately coupled mechanisms. Hence, some cell cycle regulators can influence both programmed cell death and cell division. Apoptosis eliminates defective and unwanted cells, and the cell cycle enables cells to replicate themselves. The improper regulation of apoptosis and cell cycle contributes to numerous disorders such as neurodegenerative and autoimmune diseases, viral infection, anemia, and mainly cancer. Cellular senescence is a tumor-suppressing response initiated by environmental and internal stress factors. This phenomenon has recently attained more attention due to its therapeutic implications in the field of senotherapy. In this review, the regulatory roles of lncRNAs on apoptosis, cell cycle, and senescence will be discussed. First, the role of lncRNAs in mitochondrial dynamics and apoptosis is addressed. Next, the interaction between lncRNAs and caspases, pro/antiapoptotic proteins, and also EGFR/PI3K/PTEN/AKT/mTORC1 signaling pathway will be investigated. Furthermore, the effect of lncRNAs in the cell cycle is surveyed through interaction with cyclins, cdks, p21, and wnt/β-catenin/c-myc pathway. Finally, the function of essential lncRNAs in cellular senescence is mentioned.

Down-regulation of MEG3, PANDA and CASC2 as p53-related lncRNAs in breast cancer

TP53 encodes a major tumor suppressor protein which blocks carcinogenesis process in a variety of tissues including breast tissue. Expression and function of this gene is regulated by a number of long non-coding RNAs (lncRNAs) among them are PANDA, MEG3 and CASC2. We measured expression of TP53 and these transcripts in a cohort of Iranian breast cancer patients. Expression levels of TP53, MEG3, CASC2 and PANDA were significantly lower in tumoral samples compared with non-tumoral samples (Posterior mean differences =  -4.26, -1.66, -5.98 and -3.13, respectively; P values < 0.0001). Expression of CASC2 was higher in Her2 1+ cases compared with Her2 negative cases (Beta = 1.85, P value = 0.037). Expression levels of MEG3 and TP53 were lower in grade 2 samples compared with grade 1 (Beta = -1.86, P value = 0.006 and Beta = -2.24, P value = 0.003, respectively). There was no other significant association between expression of genes and clinical variables. CASC2 had the best performance among these genes with area under curve value of 0.78 and sensitivity and specificity values of 56.33% and 88.73%, respectively (P value < 0.0001). The current investigation supports the role of TP53-related lncRNAs in the pathogenesis of breast cancer.

What is beyond LncRNAs in breast cancer: A special focus on colon cancer-associated Transcript-1 (CCAT-1)

Long non-coding RNAs (LncRNAs) play a vital role in the process of malignant transformation. In breast cancer (BC), lncRNAs field is currently under intensive investigations. Yet, the role of lncRNAs as promising diagnostic and/or prognostic biomarkers and as therapeutic target/tool among BC patients still needs a special focus from the biomedical scientists. In BC, triple negative breast cancer patients (TNBC) are the unlucky group as they are always represented with the worst prognosis and the highest mortality rates. For that reason, a special focus on TNBC and associated lncRNAs was addressed in this review. Colon cancer-associated transcript 1 (CCAT-1) is a newly discovered oncogenic lncRNA that has been emerged as a vital biomarker for diagnosis, prognosis and therapeutic interventions in multiple malignancies and showed differential expression among TNBC patients. In this review, the authors shed the light onto the general role of lncRNAs in BC and the specific functional activities, molecular mechanisms, competing endogenous ncRNA role of CCAT-1 in TNBC.

Regulatory roles of lncRNA PANDAR in breast cancer cell proliferation

Background

Breast cancer represents the second most deadly malignancy in women, and long noncoding RNAs (lncRNAs) have crucial functions in its development.

Objective

To investigate effects of the promoter of CDKN1A antisense DNA damage-activated RNA (PANDAR) on epithelial-mesenchymal transition (EMT) in breast cancer cells and their proliferation.

Methods

lncRNAs potentially regulating the transcriptional activity of the E-cadherin (E-cad, an epithelial cell marker) gene promoter were screened using a dual-luciferase reporter assay. PANDAR was overexpressed in Michigan cancer foundation 7 (MCF-7) breast cancer cells. E-cad and N-cadherin (N-cad, a mesenchymal cell marker) levels were detected by immunoblotting. Cell viability was assessed using a cell counting kit-8.

Results

PANDAR and TCONS00068220/LOC105375819 conservatively regulated the promoter activity of E-cad. PANDAR overexpression in MCF-7 inhibited E-cad expression, but upregulated N-cad. The enhanced expression of PANDAR promoted cell proliferation.

Conclusion

PANDAR is a key transcriptional repressor of E-cad and has regulatory effects on the promotion of cell proliferation. PANDAR is an oncogene in breast cancer, potentially facilitating the EMT process and promoting cell proliferation.

Long non-coding RNA (LncRNA) CASC9/microRNA(miR)-590-3p/sine oculis homeobox 1 (SIX1)/NF-κB axis promotes proliferation and migration in breast cancer

Long non-coding RNA (lncRNA)–microRNA–mRNA signaling axes have recently been shown to have a key role in the development of breast cancer (BC). In this study, we investigated how the cancer susceptibility candidate 9 (CASC9) gene affects the cell growth, invasion, migration, and apoptosis of BC cells. The levels of microRNA-590-3p (miR-590-3p), CASC9, and the sine oculis homeobox 1 (SIX1) gene were determined through qRT-PCR. We conducted cell counting kit-8 (CCK-8) assays to assess cell proliferation, transwell assays to detect cell migration/invasion, and flow cytometry to evaluate cell apoptosis. StarBase v2.0 was used to predict interactions between miR-590-3p and SIX1 or CASC9, and dual-luciferase reporter assays were used to verify these predictions. CASC9 protein was overexpressed in BC cells and tissues, while CASC9 knockdown inhibited BC cell growth, invasion, and migration and promoted apoptosis. Additionally, we verified that CASC9 competes for binding with miR-590-3p. Moreover, SIX1 was determined to be a target of miR-590–3p, and SIX1 expression was inhibited by miR-590-3p overexpression. CASC9 enhanced BC development by downregulating miR-590-3p and upregulating SIX1 during the activation of the NF-κB pathway. These data suggest that the CASC9/miR-590-3p/SIX1/NF-κB axis is involved in breast cancer progression, providing insight into the function of CASC9 in breast cancer development.

A representation learning model based on variational inference and graph autoencoder for predicting lncRNA-disease associations

Background

Numerous studies have demonstrated that long non-coding RNAs are related to plenty of human diseases. Therefore, it is crucial to predict potential lncRNA-disease associations for disease prognosis, diagnosis and therapy. Dozens of machine learning and deep learning algorithms have been adopted to this problem, yet it is still challenging to learn efficient low-dimensional representations from high-dimensional features of lncRNAs and diseases to predict unknown lncRNA-disease associations accurately.

Results

We proposed an end-to-end model, VGAELDA, which integrates variational inference and graph autoencoders for lncRNA-disease associations prediction. VGAELDA contains two kinds of graph autoencoders. Variational graph autoencoders (VGAE) infer representations from features of lncRNAs and diseases respectively, while graph autoencoders propagate labels via known lncRNA-disease associations. These two kinds of autoencoders are trained alternately by adopting variational expectation maximization algorithm. The integration of both the VGAE for graph representation learning, and the alternate training via variational inference, strengthens the capability of VGAELDA to capture efficient low-dimensional representations from high-dimensional features, and hence promotes the robustness and preciseness for predicting unknown lncRNA-disease associations. Further analysis illuminates that the designed co-training framework of lncRNA and disease for VGAELDA solves a geometric matrix completion problem for capturing efficient low-dimensional representations via a deep learning approach.

Conclusion

Cross validations and numerical experiments illustrate that VGAELDA outperforms the current state-of-the-art methods in lncRNA-disease association prediction. Case studies indicate that VGAELDA is capable of detecting potential lncRNA-disease associations. The source code and data are available at https://github.com/zhanglabNKU/VGAELDA.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12859-021-04073-z.

Long Noncoding RNA TCONS_00068220 Promotes Breast Cancer Progression by Regulating Epithelial-Mesenchymal Transition Marker E-Cadherin

BACKGROUND Long noncoding RNAs (lncRNAs) play essential roles in the regulation of breast cancer development. We herein investigated the potential role of lncRNA TCONS_00068220 in breast cancer pathogenesis. MATERIAL AND METHODS The expression levels of TCONS_00068220 in breast cancer tissues were measured by qRT-PCR. Afterwards, TCONS_00068220 was (1) overexpressed in MCF-7 breast cancer cells, and (2) silenced in MDA-MB-231 cells. Then, CCK-8 and transwell assays were conducted to detect the impact of TCONS_00068220 on cell proliferation, migration, and invasion. The expression of the epithelial-mesenchymal transition (EMT) marker E-cadherin was detected by western blot assay after upregulation or downregulation of TCONS_00068220. RESULTS TCONS_00068220 was remarkably upregulated in breast cancer tissues compared with non-cancerous tissues. In addition, TCONS_00068220 level was significantly correlated with lymphatic metastasis, Ki67 index, clinical stage, and differentiation grade. All breast cancer cell lines displayed a higher expression level of TCONS_00068220 compared with the normal breast epithelial cell line MCF-10A. Furthermore, enhanced expression of TCONS_00068220 in MCF-7 cells promoted cell proliferation, migration, invasion, and EMT, whereas TCONS_00068220 knockdown in MDA-MB-231 cells led to the opposite results. E-cadherin was negatively regulated by TCONS_00068220 in both breast cancer tissues and cell lines. Finally, TCONS_00068220 regulated MCF-7 and MDA-MB-231 cell behaviors by downregulating E-cadherin. CONCLUSIONS TCONS_00068220 promotes breast cancer cell proliferation, migration, and invasion, while facilitating the process of EMT by interacting with E-cadherin and suppressing its expression. Therefore, it may potentially serve as an oncogene in breast cancer progression.

Structural Characterization of the Hidden Peptide SHPRH-146aa Encoded by Non-Coding circ-SHPRH to Act as Tumor Suppressor

Circular RNAs belong to the class of non-coding RNA molecules, though surprisingly some of them have protein-coding potentials. However, the circular RNA circ-SHPRH is known to code for an unusual protein known as SHPRH-146aa. However, the molecular level details of the protein are not yet identified. It was proposed that the protein has its role in glioblastoma. Therefore, in this work, an attempt was made to decipher the various structural features of SHPRH-146aa. The binding interactions of the protein SHPRH-146aa with its partner protein DTL were also analyzed. The main aim of the work was to decipher the characteristics features of this unusual protein and the region on SHPRH-146aa that would form different types of non-covalent binding interactions both among itself as well as with its binding partner. In this work, we tried to elucidate the various structural and physico-chemical features of the protein as well as its mode of interactions with its binding partner. The study would therefore pave the pathway to design future wet lab experiments to delineate the appropriate structural features of the protein as well as its association with glioblastoma and neuro-degenerative diseases.

HDAC4 promotes nasopharyngeal carcinoma progression and serves as a therapeutic target

Histone deacetylases (HDACs) are involved in tumor progression, and some have been successfully targeted for cancer therapy. The expression of histone deacetylase 4 (HDAC4), a class IIa HDAC, was upregulated in our previous microarray screen. However, the role of HDAC4 dysregulation and mechanisms underlying tumor growth and metastasis in nasopharyngeal carcinoma (NPC) remain elusive. Here, we first confirmed that the HDAC4 levels in primary and metastatic NPC tissues were significantly increased compared with those in normal nasopharyngeal epithelial tissues and found that high HDAC4 expression predicted a poor overall survival (OS) and progression-free survival (PFS). Functionally, HDAC4 accelerated cell cycle G1/S transition and induced the epithelial-to-mesenchymal transition to promote NPC cell proliferation, migration, and invasion in vitro, as well as tumor growth and lung metastasis in vivo. Intriguingly, knockdown of N-CoR abolished the effects of HDAC4 on the invasion and migration abilities of NPC cells. Mechanistically, HDAC3/4 binds to the E-cadherin promoter to repress E-cadherin transcription. We also showed that the HDAC4 inhibitor tasquinimod suppresses tumor growth in NPC. Thus, HDAC4 may be a potential diagnostic marker and therapeutic target in patients with NPC.

The cross-talk between signaling pathways, noncoding RNAs and DNA damage response: Emerging players in cancer progression

The DNA damage response (DDR) pathway's primary purpose is to maintain the genome structure's integrity and stability. A great deal of effort has done to understand the exact molecular mechanisms of non-coding RNAs, such as lncRNA, miRNAs, and circRNAs, in distinct cellular and genomic processes and cancer progression. In this regard, the ncRNAs possible regulatory role in DDR via modulation of key components expression and controlling repair signaling pathway activation is validated. Therefore, in this article, we will discuss the latest developments of ncRNAs contribution in different aspects of DNA repair through regulation of ATM-ATR, P53, and other regulatory signaling pathways.

Non-Coding RNAs as Mediators of Epigenetic Changes in Malignancies

Non-coding RNAs (ncRNAs) are untranslated RNA molecules that regulate gene expressions. NcRNAs include small nuclear RNAs (snRNAs), small nucleolar RNAs (snoRNAs), ribosomal RNAs (rRNAs), transfer RNAs (tRNAs), circular RNAs (cRNAs) and piwi-interacting RNAs (piRNAs). This review focuses on two types of ncRNAs: microRNAs (miRNAs) or short interfering RNAs (siRNAs) and long non-coding RNAs (lncRNAs). We highlight the mechanisms by which miRNAs and lncRNAs impact the epigenome in the context of cancer. Both miRNAs and lncRNAs have the ability to interact with numerous epigenetic modifiers and transcription factors to influence gene expression. The aberrant expression of these ncRNAs is associated with the development and progression of tumors. The primary reason for their deregulated expression can be attributed to epigenetic alterations. Epigenetic alterations can cause the misregulation of ncRNAs. The experimental evidence indicated that most abnormally expressed ncRNAs impact cellular proliferation and apoptotic pathways, and such changes are cancer-dependent. In vitro and in vivo experiments show that, depending on the cancer type, either the upregulation or downregulation of ncRNAs can prevent the proliferation and progression of cancer. Therefore, a better understanding on how ncRNAs impact tumorigenesis could serve to develop new therapeutic treatments. Here, we review the involvement of ncRNAs in cancer epigenetics and highlight their use in clinical therapy.

KCTD12 promotes G1/S transition of breast cancer cell through activating the AKT/FOXO1 signaling

Background

Sustaining proliferation is the most fundamental step for breast cancer tumor genesis. Accelerated proliferation is usually linked to the uncontrolled cell cycle. However, the internal and external factors linked to the activation of breast cancer cell cycle are still to be investigated.

Methods

quantitative PCR (qPCR) and Western blotting assay were used to detect the expression of potassium channel tetramerization domain containing 12 (KCTD12) in breast cancer. MTT and colony formation assays were performed to evaluate the effect of KCTD12 on cell proliferation of breast cancer. Anchorage‐independent growth assay was used to examine the in vitro tumorigenesis of breast cancer cells. Flow cytometry assay, qPCR, and Western blotting were used to investigate the detailed mechanisms of KCTD12 on breast cancer progression.

Results

Herein, the result showed that the level of KCTD12 is significantly decreased in breast cancer tissues and cells, and lower level of KCTD12 predicts poorer survival for patients with breast cancer. Further cell function tests illustrated that downregulation of KCTD12 significantly promotes cell proliferation and in vitro tumor genesis. Besides, molecular biologic experiments showed that downregulation of KCTD12 can enhance the G1/S transition through activating the AKT/FOXO1 signaling.

Conclusion

Our study inferred that downregulation of KCTD12 can be a novel factor for poor prognosis in breast cancer.

The ability of arsenic metabolism affected the expression of lncRNA PANDAR, DNA damage, or DNA methylation in peripheral blood lymphocytes of laborers

Arsenic has been associated with significant effects on human health. Exposure to inorganic arsenic has been associated with the changes in gene expression. Promoter of CDKN1A antisense DNA damage activated RNA (PANDAR) expression is induced by p53 protein and DNA damage response. Here, we investigated whether the ability of arsenic metabolism in individuals affected the expression of PANDAR, DNA damage, and DNA methylation. Levels of gene expression and DNA damage were examined by the quantitative polymerase chain reaction and DNA methylation was measured by the methylation-sensitive high-resolution melting curve. In our study, we demonstrated that arsenic exposure increased PANDAR expression and DNA damage among arsenic smelting plant laborers. The PANDAR expression and DNA damage were positively linked to monomethylarsonic acid % ( R = 0.25, p < 0.05 and R = 0.32, p < 0.01) and negatively linked to dimethylarsinic acid % ( R = −0.21, p < 0.05 and R = −0.31, p < 0.01). Subjects with low primary methylation index had increased levels of DNA damage (51.62 ± 2.96 vs. 60.93 ± 3.10, p < 0.05) and methylation (17.14 (15.88–18.51) vs. 15.83 (14.82–18.00), p < 0.05). Subjects with low secondary methylation index had increased levels of PANDAR expression (4.88 ± 0.29 vs. 4.07 ± 0.23, p < 0.01) and DNA damage (17.38 (15.88–19.29) vs. 15.83 (14.82–17.26), p < 0.01). DNA methylation of PANDAR gene was linked to the regulation of its expression in peripheral blood lymphocytes among laborers ( Y = −2.08 × X + 5.64, p < 0.05). These findings suggested arsenic metabolism ability and exposure affected the expression of PANDAR, DNA damage, and DNA methylation.

Unravelling the role of long non-coding RNA - LINC01087 in breast cancer

Apoptosis is a 'programmed fate' of all cells participating in diverse physiological and pathological conditions. The role of critical regulators and their involvement in this complex multi-stage process of apoptosis weaved around non-coding RNAs (ncRNAs) is poorly deciphered in breast carcinoma (BC). Aberrant expression patterns of the ncRNAs and their interacting partners, either ncRNAs or coding RNAs or proteins at any point along these pathways, may lead to the malignant transformation of the affected cells, tumour metastasis and resistance to anticancer drugs. Longest non-coding type of ncRNAs (lncRNAs) have been considered as critical factors for the development and progression of breast cancer. The aim of our study was to identify set of novel lncRNAs interacting with microRNAs (miRNAs) or proteins that were significantly dysregulated in breast cancer using RNA-Sequencing (RNA-Seq) technique in different samples acting as oncogenic drivers contributing to cancerous phenotype involved in post-transcriptional processing of RNAs. Four lncRNAs; LINC01087, lnc-CLSTN2-1:1, lnc-c7orf65-3:3 and LINC01559:2 were selected for further analysis. Gene expression analysis of over-expressed LINC01087 in vitro reduced both cell viability and apoptosis. We integrated miRNA and mRNA (hsa-miR-548 and AKT1) expression profiles with curated regulations with lncRNA (LINC01087) which has not been previously associated with any breast cancer type, using different computational tools. The network (lncRNA→ miRNA→ mRNA) is promising for the identification of carcinoma associated genes and apoptosis signaling path highlighting the potential roles of LINC01087, hsa-miR548n, AKT1 gene which may play crucial role in proliferation.

Inhibition of lncRNA PANDAR reduces cell proliferation, cell invasion and suppresses EMT pathway in breast cancer

BACKGROUND

The PANDAR, a novel identified long non-coding RNA, is previously reported to function as oncogene in various cancers including breast cancer. the study aims to explore the role of lncRNA PANDAR for cell proliferation and invasion of breast cancer, and its underlying mechanism.

METHODS

The expression of lncRNA PANDAR in 65 pairs of breast cancer tissues and adjacent normal tissues was detected by quantitative Real-time polymerase chain reaction (qRT-PCR) assay. The association between lncRNA PANDAR expression and clinical factors of breast cancer was analyzed. Cell proliferation, cell colony formation and cell invasion assays were performed to detect the effects of lncRNA PANDAR expression tumor proliferation and invasion abilities. The western blot analysis was also performed to detected the EMT related makers expression of E-cadherin, Vimentin, MMP2 and MMP9.

RESULTS

We demonstrated that lncRNA PANDAR expression was higher in breast cancer tissues and cells compared with adjacent normal tissues and the normal mammary epithelial cell line, respectively. Higher lncRNA PANDAR expression positively associated with lymph node metastasis and advanced clinical stage in patients. In vitro, we demonstrated that knockdown of lncRNA PANDAR significantly suppressed cell proliferation, cell colony formation and cell invasion ability in breast cells. Furthermore, we verified that knockdown of lncRNA PANDAR dramatically inhibited cell epithelial-mesenchymal transition (EMT) pathway by downregulating Vimentin, MMP2 and MMP9 expression, but upregulating E-cadherin expression in breast cancer.

CONCLUSIONS

Our results proved that PANDAR may serve as potential target of breast cancer treatment.

Prognostic and Clinicopathological Significance of Long Non-coding RNA PANDAR Expression in Cancer Patients: A Meta-Analysis

Background: Long non-coding RNA PANDAR is an emerging non-coding RNA mapping to 6p21.2. It underlies metastatic progression and chromosomal instability in a variety of cancers. Despite the fact that recent studies have revealed that lncRNA PANDAR may be a potential prognostic biomarker for patients with cancer, there has still been controversy on the prognostic value of PANDAR. Methods: Databases of PubMed, Embase, SinoMed, and Web of Science were carefully searched and the literature which investigated the prognostic value of PANDAR expression among human cancers was collected for further analysis. Odds ratios (ORs) or hazards ratios (HRs) with 95% confidence intervals (CIs) were pooled to estimate the relation between PANDAR expression and survival or clinicopathological characteristics of cancer patients. Results: There were 13 eligible studies in total, with 1,465 patients enlisted in this meta-analysis. All the eligible studies complied with the case-control study. The outcome showed that the elevated expression level of PANDAR was significantly related to poor overall survival (OS) (pooled HR 1.72, 95%CI 1.14-2.60). However, high or low expression of PANDAR did not differ in the prediction of event-free survival (EFS). Moreover, we discovered that high PANDAR expression was closely related to decreased OS in colorectal cancer (pooled HR 3.43, 95%CI 2.06-5.72) and reduced expression level of PANDAR was markedly related to poor OS (pooled HR 0.65, 95%CI 0.45-0.88) in non-small cell lung cancer. However, the expression level of PANDAR had no significant association with OS in renal cell carcinoma (pooled HR 1.19, 95%CI 0.56-2.50). Moreover, after analysis, we discovered that the high expression level of PANDAR was associated closely with the depth of invasion (pooled OR 3.95, 95%CI 2.36-6.63), lymph node metastasis (pooled OR 1.92, 95%CI 0.93-3.98), tumor stage (pooled OR 2.05, 95%CI 0.99-4.27), and distant metastasis (pooled OR 2.87, 95%CI 1.60-5.16). Conclusions: Our study revealed that increased PANDAR expression may serve as an adverse prognostic biomarker for cancer patients, thus helping the clinical decision-making process.

Long non-coding RNAs in non-small cell lung cancer: functions and distinctions from other malignancies

Lung cancer leads to the most cancer-related death in the world. It was shown from the increasing evidences that long non-coding RNAs (lncRNAs) are emerging as molecules for diagnosis, prognosis and even therapy of lung cancer and other malignancies. The biological functions or involved signaling pathways of lncRNAs are always found to be inconsistent among different types of malignancies. However, no available literature has systemically summarized differences in the functions and underlying molecular mechanisms of lncRNAs between lung cancer and other cancers. In this review, the biological functions and molecular mechanisms of lncRNAs in lung cancer were introduced. Furthermore, their functional differences between lung cancer and other malignancies were discussed. Finally, their potential clinical applications in future lung cancer therapy were focused on.

LncRNAs Regulatory Networks in Cellular Senescence

Long noncoding RNAs (lncRNAs) are a class of transcripts longer than 200 nucleotides with no open reading frame. They play a key role in the regulation of cellular processes such as genome integrity, chromatin organization, gene expression, translation regulation, and signal transduction. Recent studies indicated that lncRNAs are not only dysregulated in different types of diseases but also function as direct effectors or mediators for many pathological symptoms. This review focuses on the current findings of the lncRNAs and their dysregulated signaling pathways in senescence. Different functional mechanisms of lncRNAs and their downstream signaling pathways are integrated to provide a bird’s-eye view of lncRNA networks in senescence. This review not only highlights the role of lncRNAs in cell fate decision but also discusses how several feedback loops are interconnected to execute persistent senescence response. Finally, the significance of lncRNAs in senescence-associated diseases and their therapeutic and diagnostic potentials are highlighted.

KLF5 regulated lncRNA RP1 promotes the growth and metastasis of breast cancer via repressing p27kip1 translation

Increasing evidence suggest that lncRNAs (long noncoding RNAs) play important roles in human cancer. Breast cancer is a heterogeneous disease and the potential involvement of lncRNAs in breast cancer remains unexplored. In this study, we characterized a novel lncRNA, RP1-5O6.5 (termed as RP1). We found that RP1 was highly expressed in breast cancer and predicted poor prognosis of breast cancer patients. Gain-of-function and loss-of-function assays showed that RP1 promoted the proliferation and metastasis of breast cancer cells in vitro and in vivo. Mechanistically, RP1 maintained the EMT and stemness states of breast cancer cells via repressing p27kip1 protein expression. RP1 combined with the complex p-4E-BP1/eIF4E to prevent eIF4E from interacting with eIF4G, therefore attenuating the translational efficiency of p27kip1 mRNA. Furthermore, we found that p27kip1 evidently downregulated Snail1 but not ZEB1 to inhibit invasion of breast cancer cells. Kruppel-like factor 5 (KLF5) was positively correlated with RP1 in breast cancer tissues. Moreover, we demonstrated that KLF5 recruited p300 to the RP1 promoter to enhance RP1 expression. Taken together, our findings demonstrated that KLF5-regulated RP1 plays an oncogenic role in breast cancer by suppressing p27kip1, providing support for the clinical investigation of therapeutic approaches focusing on RP1.

Long non-coding RNAs: Functional regulatory players in breast cancer

Historically, the long-held protein-centered bias has denoted 98% of the human genome as 'Junk' DNA. However, the current work has shifted the perception of such 'junk' transcriptional products to functional regulatory molecules. The recent surveillance of the human transcriptome has highlighted the pivotal role of such non-coding RNA (ncRNA) molecules in diverse physiological and pathological conditions. Long non-coding RNA (lncRNA) is a recent class of ncRNA molecules that is still in its infancy stage. The main focus of this review is to unravel the importance of lncRNAs in the most prevalent malignancy among females which is Breast Cancer (BC). A specific focus on lncRNAs as prognostic markers among BC patients showing molecular subtype heterogeneity was also tackled in this review. Finally, the functional and the mechanistic roles of such booming ncRNA molecules in shaping the fate of the BC progression have been highlighted.

Mechanisms of Antisense Transcription Initiation with Implications in Gene Expression, Genomic Integrity and Disease Pathogenesis

Non-coding antisense transcripts arise from the strand opposite the sense strand. Over 70% of the human genome generates non-coding antisense transcripts while less than 2% of the genome codes for proteins. Antisense transcripts and/or the act of antisense transcription regulate gene expression and genome integrity by interfering with sense transcription and modulating histone modifications or DNA methylation. Hence, they have significant pathological and physiological relevance. Indeed, antisense transcripts were found to be associated with various diseases including cancer, diabetes, cardiac and neurodegenerative disorders, and, thus, have promising potentials for prognostic and diagnostic markers and therapeutic development. However, it is not clearly understood how antisense transcription is initiated and epigenetically regulated. Such knowledge would provide new insights into the regulation of antisense transcription, and hence disease pathogenesis with therapeutic development. The recent studies on antisense transcription initiation and its epigenetic regulation, which are limited, are discussed here. Furthermore, we concisely describe how antisense transcription/transcripts regulate gene expression and genome integrity with implications in disease pathogenesis and therapeutic development.

The cisplatin-induced lncRNA PANDAR dictates the chemoresistance of ovarian cancer via regulating SFRS2-mediated p53 phosphorylation

As a component of p53-dependent lncRNA (long non-coding RNA), PANDAR (the promoter of CDKN1A antisense DNA damage activated RNA) participates in the epigenetic regulation in human cancer. However, the involvement of PANDAR in cancer chemoresistance is unknown. In this study, we report that PANDAR serves as a negative regulator of cisplatin sensitivity in human ovarian cancer via PANDAR-SRFS2-p53 feedback regulation in nuclear. Our data showed that among the drugs commonly used in ovarian cancer therapy, cisplatin induces higher levels of PANDAR compared with doxorubicin and paclitaxel. We also proved that PANDAR exhibited higher expression in cisplatin-resistant ovarian cancer tissues and cells, compared with cisplatin-sensitive ones, and this expression pattern depends on wild-type p53 (wt-p53), not mutant-p53 (mt-p53). In vitro and in vivo, PANDAR overexpression improved cell survival rate and tumor growth in response to cisplatin, while depletion of PANDAR leads to a reduced tumor growth. Further investigation revealed that PANDAR-reduced cisplatin sensitivity was likely or partly due to the PANDAR-binding protein SFRS2 (arginine/serine-rich 2), a splicing factor with the ability to negative regulate p53 and its phosphorylation at Serine 15 (Ser15). This feedback regulation of PANDAR–SFRS2–p53 leads to a reduced transactivation of p53-related pro-apoptotic genes, such as PUMA (p53-upregulated modulator of apoptosis). In addition, in platinum-treated patients with relapsed ovarian cancer, resistant period was positively correlated with the expression of PANDAR and SFRS2, and inversely associated with expression of p53-Ser15 and PUMA in these clinical tissues. Last but not least, the role of PANDAR in chemoresistance was confirmed in patients with ovarian cancer. These findings reveal a novel regulatory maneuver of cancer cells in response to chemostress, and might shed light on overcoming cisplatin resistance in ovarian cancer.

Overexpression of lncRNA PANDAR predicts adverse prognosis in acute myeloid leukemia

Background and purpose

Abundant studies have shown that lncRNA PANDAR plays an oncogenic role in human solid tumors. Although abnormal expression of PANDAR has been well investigated in solid tumors, it was rarely studied in hematologic diseases. Hence, the aim of this study was to determine the PANDAR expression level and its clinical significance in patients with acute myeloid leukemia (AML).

Materials and methods

For detecting the expression level of PANDAR in 119 AML patients and 26 controls, real-time quantitative PCR was used in this study. The prognostic values were evaluated by using Kaplan-Meier analysis, Cox regression analyses, and logistic regression analysis.

Results

PANDAR was significantly overexpressed in AML and might be a promising biomarker which could distinguish AML from normal samples (P<0.001). Patients with high expression of PANDAR (PANDAR ^high) were older and showed higher bone marrow blasts than patients in PANDAR ^low group (P=0.029 and 0.032, respectively). Significant differences between these groups were also detected regarding risk group and karyotype finding (P=0.009 and 0.041, respectively). Importantly, PANDAR ^high patients presented a significant lower complete remission rate compared to PANDAR ^low patients (P<0.001). Furthermore, Kaplan-Meier analysis showed that PANDAR ^high patients had shorter overall survival compared to PANDAR ^low patients observing the whole AML cohort, and also in the non-M3 group of patients (P<0.001 and P=0.005, respectively). Multivariate analysis of Cox and logistic regression analysis confirmed that high PANDAR expression was an independent unfavorable risk factor for overall survival and complete remission in both observed patient groups.

Conclusion

These results revealed that PANDAR was overexpressed in AML, and that higher PANDAR expression was associated with poor clinical outcome. Our study therefore suggests that PANDAR expression is a promising biomarker for prognostic prediction for AML.

High expression of ZBED1 affects proliferation and apoptosis in gastric cancer

BACKGROUND

ZBED1 (zinc finger BED-type containing 1) is a transcription factor. However, its expression, role and clinical significance in cancer are unclear. The purpose of this study is to investigate the expression of ZBED1 and its effect on the proliferation of gastric cancer (GC).

METHODS

Quantitative PCR was used to detect the mRNA level of ZBED1 in GC tissues and normal gastric tissues. Proliferation and colony formation assays were conducted when ZBED1 was expressed ectopically or silenced by constructed vectors. Moreover, chemotherapy-drug induced apoptosis rates were examined by flow cytometry when ZBED1 was expressed ectopically or silenced.

RESULTS

The mRNA level of ZBED1 was significantly elevated in 10 out of 11 cases of GC tumor tissue specimens. Results of our analysis derived from a public clinical microarray database suggest that a high expression of ZBED1 predicts a poor outcome. ZBED1 promotes cell proliferation and colony formation. Moreover, ZBED1 decreased the chemosensitivity of GC cells.

CONCLUSIONS

ZBED1 expression is up-regulated in GC cells. ZBED1 promotes proliferation and decreases the chemosensitivity of GC cells. ZBED1 may be a potential therapeutic target and predictive biomarker in gastric cancer.

PANDAR: a pivotal cancer-related long non-coding RNA in human cancers

Long non-coding RNAs (lncRNAs), non-protein-coding RNAs that are more than 200 nucleotides in length, have been demonstrated to play a vital role in the pathophysiology of human diseases, particularly in tumorigenesis and progression of cancers. Dysregulation of lncRNAs, which serve as either oncogenes or tumor suppressor genes, is involved in diverse cellular processes, such as proliferation, dedifferentiation, migration, invasion and anti-apoptosis. Promoter of CDKN1A antisense DNA damage-activated RNA (PANDAR), which was recently found to manifest aberrant expression in various malignancies including non-small cell lung cancer, hepatocellular carcinoma, colorectal cancer and gastric cancer, is a novel cancer-related lncRNA. Deregulation of PANDAR contributes to tumorigenesis and progression of cancers, suggesting that PANDAR is likely to represent a viable biomarker and therapeutic target for human cancers. In this review, we summarize current evidence regarding the biological functions and mechanisms of PANDAR during tumor development.

Long non-coding RNA PANDAR overexpression serves as a poor prognostic biomarker in oral squamous cell carcinoma

BACKGROUND

Long non-coding RNA (lncRNA) has been found to play a crucial role in carcinogenesis and in evaluating prognosis of multiple neoplasms. PANDAR (promoter of CDKN1A antisense DNA damage activated RNA), a newly discovered cancer-associated RNA is abnormally expressed in a wide variety of tumors. Expression and the functional role of PANDAR in human oral squamous cell carcinoma (OSCC), however, needs to be completely elucidated.

METHODS

Quantitative real-time PCR (qRT-PCR) was applied to detect expression levels of lncRNA PANDAR in OSCC tissues and corresponding paracancerous normal tissues in 92 OSCC patients, four OSCC cell lines, and a normal oral keratinocytes cell line. Association between expression of PANDAR and clinicopathological features of OSCC patients was also analyzed. For analysis of overall survival data, Kaplan-Meier curves were constructed. The prognostic value of PANDAR was examined by Cox regression analysis. PANDAR levels were knocked down in OSCC cell line Tca8113 by using PANDAR siRNA. Function of PANDAR on tumor cell proliferation, migration, and invasion was further evaluated by MTT and Transwell assays in vitro.

RESULTS

PANDAR was highly expressed in OSCC tissues and cell lines (P < 0.05) and its high expression level was found to be closely associated with advanced TNM stage (P = 0.004) and positive distant metastasis (P = 0.001). Furthermore, overall survival rate of OSCC patients with high PANDAR expression was poorer than patients with low PANDAR expression (P < 0.001). Cox proportional hazards model analysis showed that expression level of PANDAR can be used as an independent prognostic indicator for OSCC. Functionally, knockdown of PANDAR can inhibit proliferation, invasion, and migration of OSCC cells.

CONCLUSIONS

Our findings indicate that PANDAR may serve as a promising prognostic biomarker and a new molecular target for new therapies for OSCC patients.

Deciphering the roles of lncRNAs in breast development and disease

Breast cancer is the second leading cause of cancer related deaths in women. It is therefore important to understand the mechanisms underlying breast cancer development as well as raises the need for enhanced, non-invasive strategies for novel prognostic and diagnostic methods. The emergence of long non-coding RNAs (lncRNAs) as potential key players in neoplastic disease has received considerable attention over the past few years. This relatively new class of molecular regulators has been shown from ongoing research to act as critical players for key biological processes. Deregulated expression levels of lncRNAs have been observed in a number of cancers including breast cancer. Furthermore, lncRNAs have been linked to breast cancer initiation, progression, metastases and to limit sensitivity to certain targeted therapeutics. In this review we provide an update on the lncRNAs associated with breast cancer and mammary gland development and illustrate the versatility of such lncRNAs in gene control, differentiation and development both in normal physiological conditions and in diseased states. We also highlight the therapeutic and diagnostic potential of lncRNAs in cancer.

Long non-coding RNA as potential biomarkers in non-small-cell lung cancer: What do we know so far?

Non-small-cell lung cancer (NSCLC) remains one of the most frequent types of lung cancer characterized by its local advancement at diagnosis. Therefore, identification of new prognostic biomarkers has become one of the most important issue in NSCLC therapy. It is now well understood that genetic and epigenetic alterations are responsible for NSCLC development. Moreover, it has been recently revealed that the non-protein coding regions of the genome may serve as a template for transcription of various type of RNAs, collectively referred to as non-coding RNAs. Non-coding RNAs, including long non-coding RNAs (lncRNAs) are involved in multiple cellular processes and it has been suggested that aberrant expression of lncRNAs may lead to tumour development, including NSCLC. Furthermore, some of the established risk factors for NSCLC may have an impact on expression level of several types of lncRNAs, and thus, affect the lung carcinogenesis through lncRNAs regulation. In this review, we would like to summarise the to-date knowledge about lncRNAs as potential biomarkers in NSCLC and the role of various environmental factors, such as smoking and air pollution, in development and progression of this tumour and their effect on lncRNAs expression.

Long noncoding RNA PANDAR blocks CDKN1A gene transcription by competitive interaction with p53 protein in gastric cancer

Emerging evidence indicates that lncRNAs play important roles in cancer tumourigenesis and could be used as potential diagnostic biomarkers or therapeutic targets. However, the clinical significance and molecular mechanism of lncRNAs in gastric cancer (GC) is still unclear. The aim of this study was to explore the expression and role of lncRNAs in GC. The relative expression level of lncRNAs in GC samples was examined by an lncRNA microarray analysis, northern blot analysis and qRT-PCR analysis. A Kaplan−Meier survival analysis and univariate and multivariate Cox proportional hazards models were performed to evaluate the clinical and prognostic significance of PANDAR (promoter of CDKN1A antisense DNA damage activated RNA) in GC patients. The binding activity of PANDAR with the p53 protein was analysed by an RNA immunoprecipitation analysis and RNA pull-down analysis. The depletion of PANDAR was conducted using the CRISPR/Cas9 system for PANDAR. The biological functions of PANDAR in GC cells were determined both in vitro and in vivo. Upregulated PANDAR in GC patients was positively correlated with increased tumour size, advanced TNM classification and a poor survival rate in GC patients. The ROC curves identified that the PANDAR level was a marker for discriminating the early-stage tumour group from the healthy group, the metastasis group from the non-metastasis group and the chemoresistance group from the chemosensitive group in GC patients. As a target, the CDKN1A gene was successfully downregulated by PANDAR. PANDAR controlled the transcription of the CDKN1A gene by competitively binding with p53 protein. In combination with a p53 activator (nutlin3), the knockout of PANDAR by CRISPR/Cas9 technology synergistically inhibited GC tumour growth in vivo. Our results suggest that the PANDAR is a powerful diagnostic and therapeutic marker for patients with GC and, combined with other chemotherapeutics, may have distinct antitumour effects.

Long non-coding PANDAR as a novel biomarker in human cancer: A systematic review

OBJECTIVES

Long non-coding RNAs (lncRNAs) are characterized as a group of RNAs that more than 200 nucleotides in length and have no protein-coding function. More and more evidences provided that lncRNAs serve as key molecules in the development of cancer. Deregulation of lncRNAs functions as either oncogenes or tumour suppressor genes in various diseases. Recently, increasing studies about PANDAR in cancer progression were reported. In our review, we will focus on the current research on the character of PANDAR include the clinical management, tumour progression and molecular mechanisms in human cancers.

MATERIALS AND METHODS

We summarize and analyze current studies concerning the biological functions and mechanisms of lncRNA PANDA in tumour development. The related studies were obtained through a systematic search of Pubmed.

RESULTS

PANDAR was a well-characterized oncogenic lncRNA and widely overexpressed in many tumours. PANDAR is upregulated in many types of cancer, including colorectal cancer, lung cancer, renal cell carcinoma, cholangiocarcinoma, osteosarcoma, thyroid cancer and other cancers. Upregulation of PANDAR was significantly associated with advanced tumour weights, TNM stage and overall survival. Furthermore, repressed of PANDAR would restrain proliferation, migration and invasion.

CONCLUSION

PANDAR may act as a powerful tumour biomarker for cancer diagnosis and treatment.

Natural Antisense Transcripts: Molecular Mechanisms and Implications in Breast Cancers

Natural antisense transcripts are RNA sequences that can be transcribed from both DNA strands at the same locus but in the opposite direction from the gene transcript. Because strand-specific high-throughput sequencing of the antisense transcriptome has only been available for less than a decade, many natural antisense transcripts were first described as long non-coding RNAs. Although the precise biological roles of natural antisense transcripts are not known yet, an increasing number of studies report their implication in gene expression regulation. Their expression levels are altered in many physiological and pathological conditions, including breast cancers. Among the potential clinical utilities of the natural antisense transcripts, the non-coding|coding transcript pairs are of high interest for treatment. Indeed, these pairs can be targeted by antisense oligonucleotides to specifically tune the expression of the coding-gene. Here, we describe the current knowledge about natural antisense transcripts, their varying molecular mechanisms as gene expression regulators, and their potential as prognostic or predictive biomarkers in breast cancers.

Downregulation of LncRNA-RP11-317J10.2 promotes cell proliferation and invasion and predicts poor prognosis in colorectal cancer

OBJECTIVES

Using microarray analysis, we previously showed that many lncRNAs are differentially expressed in colorectal cancer (CRC) tissues compared with normal tissues, suggesting that lncRNAs may be involved the initiation and progression of CRC. In this study, we investigated the expression and function of lncRNA-RP11-317J10.2 in human CRC tissues and cell lines.

METHODS

LncRNA-RP11-317J10.2 expression level was analyzed in 52 colon cancer and cell lines. We used shRNA to knock-down the expression of RP11-317J10.2, and then proliferation assay, colony formation assay, Boyden chamber assay, FACS and Kaplan-Meier survival analysis were performed to explore the biological effect of RP11-317J10.2. Cyclin D1 protein level was detected by Western blot.

RESULTS

LncRNA-RP11-317J10.2 is downregulated in CRC and decreased expression is significantly associated with advanced tumor stage, larger tumor size and poor prognosis. RNA interference-mediated knockdown of lncRNA-RP11-317J10.2 in CRC cells promotes G1-to-S cell cycle transition, enhances invasiveness and facilitates cell growth in vitro and in mouse tumor xenograft models. Cyclin D1 was upregulated by lncRNA-RP11-317J10.2 knockdown, and co-expression of cyclin D1-targeting siRNA abrogates the pro-tumorigenic effects of lncRNA-RP11-317J10.2 knockdown.

CONCLUSIONS

This study reveals a crucial role for lncRNA-RP11-317J10.2 in CRC growth and invasion via upregulation of cyclin D1 expression and suggests that expression of this lncRNA may be a potential prognostic biomarker for CRC.

Over Expression of Long Non-Coding RNA PANDA Promotes Hepatocellular Carcinoma by Inhibiting Senescence Associated Inflammatory Factor IL8

It has been reported that long non-coding RNA PANDA was disregulated in varieties types of tumor, but its expression level and biological role in hepatocellular carcinoma (HCC) remains contradictory. We detected PANDA expression in two independent cohorts (48 HCC patients following liver transplantation and 84 HCC patients following liver resection), and found that PANDA was down-regulated in HCC. Thereafter we explored its function in cancer biology by inversing its low expression. Surprisingly, overexpression of PANDA promoted HCC proliferation and carcinogenesis in vitro and in vivo. Mechanistically, PANDA repressed transcriptional activity of senescence associated inflammatory factor IL8, which leaded to inhibition of cellular senescence. Therefore, our research help to better understand the complex role of PANDA in HCC, and suggest more thoughtful strategies should be applied before it can be treated as a potential therapeutic target.

Upregulated long noncoding RNA PANDAR predicts an unfavorable prognosis and promotes tumorigenesis in cholangiocarcinoma

Cholangiocarcinoma (CCA) is one of the most malignant human cancers with increasing incidence worldwide. LncRNAs have emerged as gene regulators and prognostic biomarkers in a variety of neoplasms. PANDAR, a novel cancer-related lncRNA, has been reported to be upregulated in diverse human carcinomas. In this study, we aimed to investigate the clinical significance of lncRNA PANDAR in CCA and explore its functional roles in CCA cells including cell proliferation, apoptosis, migration, invasion and epithelial-to-mesenchymal transition (EMT). The results showed that PANDAR was significantly upregulated in CCA tissue specimens and cell lines, and its high expression was closely associated with lymph node invasion (P=0.004), TNM stage (P=0.034) and postoperative relapse (P=0.006) in patients with CCA. Thus, overexpression of PANDAR could serve as an independent prognostic biomarker of CCA. Furthermore, silencing of PANDAR followed by siRNA significantly inhibited cell proliferation and increased apoptosis in CCA cells. In addition, suppression of PANDAR impaired migration and invasion capacity in vitro partly by affecting EMT. Overall, our findings showed that lncRNA PANDAR serves as a novel prognostic biomarker and therapeutic target for CCA.

An increase in long non-coding RNA PANDAR is associated with poor prognosis in clear cell renal cell carcinoma

Background

Nearly 30% of clear cell renal cell carcinoma (ccRCC) patients present with metastasis at the time of diagnosis, and the prognosis for these patients is poor. Therefore, novel potential prognostic biomarkers and therapeutic targets for ccRCC could be helpful. Emerging evidence indicates that lncRNAs play important roles in cancer tumorigenesis and could be used as potential biomarkers or therapeutic targets. PANDAR (promoter of CDKN1A antisense DNA damage activated RNA) is a relatively novel lncRNA that plays an important role in the development of multiple cancers. However, the clinical significance and molecular mechanism of PANDAR in ccRCC are still elusive. In the present study, we attempted to elucidate the role of PANDAR in ccRCC.

Methods

The relative expression level of lncRNA PANDAR was quantified by real-time qPCR in 62 paired ccRCC tissues and in renal cancer cell lines, and its association with overall survival was assessed by statistical analysis. The biological functions of lncRNA PANDAR on ccRCC cells were determined both in vitro and in vivo.

Results

PANDAR expression was significantly upregulated in tumor tissues and cell lines compared with normal counterparts. Moreover, PANDAR served as an independent predictor of overall survival, and increased PANDAR expression was positively correlated with an advanced TNM stage. Further experiments demonstrated that PANDAR silencing can significantly inhibit cell proliferation and invasion, induce cell cycle arrest in the G1 phase and significantly promote apoptosis in 7860 and Caki-1 cell lines. In addition, in vivo experiments confirmed that downregulation of PANDAR inhibited the tumorigenic ability of 7860 cells in nude mice. Silencing of PANDAR also inhibited the expression of Bcl-2 and Mcl-1 and upregulated the expression of Bax in vivo.

Conclusions

Our results suggest that PANDAR is involved in ccRCC progression and may serve as a potential prognostic biomarker and therapeutic target.

Expression of long non-coding RNA PANDAR and its prognostic value in colorectal cancer patients

BACKGROUND

Long noncoding RNAs (lncRNAs) are emerging as key molecules in human cancer. In the present study, we explored the role of the lncRNA PANDAR in colorectal cancer (CRC).

METHODS

The relative expression level of lncRNA PANDAR in CRC tissues and cell lines was determined by quantitative real-time polymerase chain reaction (qRT-PCR). The associations between PANDAR expression and clinicopathological features of CRC patients were further analyzed. Kaplan-Meier survival analysis was performed to evaluate the value of PANDAR in the prognosis of CRC patients. Furthermore, the biological function of PANDAR on CRC cell growth, apoptosis and mobility was investigated through MTT, flow cytometry, transwell migration and invasion assays in vitro.

RESULTS

The expression level of PANDAR was higher in CRC tissues and cells compared with adjacent nontumor tissues and normal colonic cell line NCM460. PANDAR expression was significantly correlated with local invasion, lymph node metastasis and TNM stage. Kaplan-Meier analysis showed that patients with high PANDAR expression had poorer overall survival than patients with low PANDAR expression. Multivariate Cox regression analysis indicated that PANDAR might be an independent prognostic factor for CRC patients. Furthermore, PANDAR knockdown significantly inhibited cell proliferation, cycle progression, migration and invasion of CRC in vitro.

CONCLUSIONS

Our results suggest that high expression of PANDAR was involved in CRC progression and could act as an independent biomarker for prognosis of CRC patients.

Knockdown of lncRNA-PANDAR suppresses the proliferation, cell cycle and promotes apoptosis in thyroid cancer cells

Long non-coding RNAs (lncRNAs) have been found to show important regulatory roles in various human cancers. Lnc-RNA PANDAR is a novel identified lncRNA that was previously reported to show abnormal expression pattern in various cancers. However, little is known of its expression and biological function in thyroid cancer. Here, we used the quantitative real-time PCR (qRT-PCR) to determine the expression of PANDAR in 64 thyroid cancer tissues. We found that expression of PANDAR was up-regulated in thyroid cancer tissues compared with adjacent non-tumor tissues. Functional assays in vitro demonstrated that knockdown of PANDAR could inhibit proliferation, cell cycle progression, induces the apoptosis, inhibit invasion of thyroid cancer cells. Thus, our study provides evidence that PANDAR may function as a potential target for treatment for patients with thyroid cancer.