Silencing of the long non-coding RNA LINC00265 triggers autophagy and apoptosis in lung cancer by reducing protein stability of SIN3A oncogene.

Background: Long non-coding RNAs are important regulators in cancer biology and function either as tumor suppressors or as oncogenes. Their dysregulation has been closely associated with tumorigenesis. LINC00265 is upregulated in lung adenocarcinoma and is a prognostic biomarker of this cancer. However, the mechanism underlying its function in cancer progression remains poorly understood. Methods: Here, the regulatory role of LINC00265 in lung adenocarcinoma was examined using lung cancer cell lines, clinical samples, and xenografts. Results: We found that high levels of LINC00265 expression were associated with shorter overall survival rate of patients, whereas knockdown of LINC00265 inhibited proliferation of cancer cell lines and tumor growth in xenografts. Western blot and flow cytometry analyses indicated that silencing of LINC00265 induced autophagy and apoptosis. Moreover, we showed that LINC00265 interacted with and stabilized the transcriptional co-repressor Switch-independent 3a (SIN3A), which is a scaffold protein functioning either as a tumor repressor or as an oncogene in a context-dependent manner. Silencing of SIN3A also reduced proliferation of lung cancer cells, which was correlated with the induction of autophagy. These observations raise the possibility that LINC00265 functions to promote the oncogenic activity of SIN3A in lung adenocarcinoma. Conclusions: Our findings thus identify SIN3A as a LINC00265-associated protein and should help to understand the mechanism underlying LINC00265-mediated oncogenesis.

Glial Activation, Mitochondrial Imbalance, and Akt/mTOR Signaling May Be Potential Mechanisms of Cognitive Impairment in Heart Failure Mice.

Heart failure (HF) is a major health burden worldwide, with approximately half of HF patients having a comorbid cognitive impairment (CI). However, it is still unclear how CI develops in patients with HF. In the present study, a mice model of heart failure was established by ligating the left anterior descending coronary artery. Echocardiography 1 month later confirmed the decline in ejection fraction and ventricular remodeling. Cognitive function was examined by the Pavlovian fear conditioning and the Morris water maze. HF group cued fear memory, spatial memory, and learning impairment, accompanied by activation of glial cells (astrocytes, microglia, and oligodendrocytes) in the hippocampus. In addition, the mitochondrial biogenesis genes TFAM and SIRT1 decreased, and the fission gene DRP1 increased in the hippocampus. Damaged mitochondria release excessive ROS, and the ability to produce ATP decreases. Damaged swollen mitochondria with altered morphology and aberrant inner-membrane crista were observed under a transmission electron microscope. Finally, Akt/mTOR signaling was upregulated in the hippocampus of heart failure mice. These findings suggest that activation of Akt/mTOR signaling, glial activation, and mitochondrial dynamics imbalance could trigger cognitive impairment in the pathological process of heart failure mice.

Circular RNA-mediated ceRNA network was identified in human lung adenocarcinoma by high-throughput sequencing.

OBJECTIVES: Aberrantly expressed circular RNAs (circRNAs) have been detected in many types of tumors. Hence, they are currently investigated as candidate biomarkers for diagnostic and potential targets for therapy in cancers. The objective of this study was to assess the expression profile of circRNA in lung adenocarcinoma (LUAD). METHODS: This study included 14 pairs of postoperative lung adenocarcinoma specimens, including cancer tissues and matched adjacent tissues. Second-generation sequencing was applied to the specimens to determine the circRNA expression in them among the 5242 distinct circRNAs detected. RESULTS: We identified a total of 18 significantly dysregulated circRNAs in the LUAD tissues: upregulation in four and downregulation in 14. ROC (The receiver operating characteristic curve) further suggested that hsa_circ_0120106, has_circ_0007342, has_circ_0005937, and circRNA_0000826 could potentially be used as biomarkers in the diagnosis of LUAD. Furthermore, study of the circRNA-microRNA (miRNA)-messenger RNA (mRNA) revealed interactions between the 18 dysregulated circRNA and several cancer-related miRNAs. Finally, a further Kyoto Encyclopedia of Genes and Genomes analysis showed that the cell cycle phase transition, p53 signaling pathway, AMP-activated protein kinase (AMPK) relative signaling pathway, and so on were key putative pathways in the process of LUAD. CONCLUSIONS: These findings demonstrated the correlation between abnormality in circRNA expression and LUAD, which lays the foundation of making CircRNAs candidate biomarkers in the diagnosis of LUAD.

LncRNA GSCAR promotes glioma stem cell maintenance via stabilizing SOX2 expression.

Gliomas are the most aggressive type of malignant brain tumors. Recent studies have demonstrated that the existence of glioma stem cells (GSCs) is critical for glioma recurrence, metastasis, and chemo- or radio-therapy resistance. Temozolomide (TMZ) has been used as an initial therapy for gliomas. However, the overall survival time is still limiting due to the lack of effective targets and treatment options. Therefore, identifying novel biomarkers for gliomas, especially for GSCs, is important to improve the clinical outcome in the future. In this study, we identify a human-specific long non-coding RNA (lncRNA, ENSG00000250377), termed GSCAR (glioma stem cell associated lncRNA), which is highly expressed in glioma cancerous tissues and cell lines. We reveal that GSCAR positively correlates with tumor grade. Glioma patients with GSCAR high expression exhibit shortened overall survival time, compared to patients with GSCAR low expression. Furthermore, we show that GSCAR knockdown by shRNAs or antisense oligonucleotide (ASO) reduces tumor cell proliferation, migration and xenograft tumor formation abilities. Mechanistic study shows that GSCAR acts as a ceRNA (competing endogenous RNA) for miR-6760-5p to promote the expression of oncogene SRSF1 (serine and arginine rich splicing factor 1). In addition, GSCAR mediates the protein complex formation between DHX9 (DExH-Box helicase 9) and IGF2BP2 (insulin-like growth factor 2 mRNA-binding protein 2), leading to the stabilization of SOX2 (sex-determining region Y-box 2) mRNA and then the transcriptional activation of GSCAR. Depleting GSCAR reduces SOX2 expression and GSC self-renewal ability, but promotes tumor cell responses to TMZ. These findings uncover that GSCAR/miR-6760-5p/SRSF1 axis and GSCAR/DHX9-IGF2BP2/SOX2 positive feedback loop are critical for glioma progression, which could be used as prognostic biomarkers and therapeutic targets in the future.

Hypoxia-induced GLT8D1 promotes glioma stem cell maintenance by inhibiting CD133 degradation through N-linked glycosylation.

Gliomas are the most aggressive primary brain tumors. However, no significant improvement in survival has been achieved with the addition of temozolomide (TMZ) or radiation as initial therapy, although many clinical efforts have been carried out to target various signaling pathways or putative driver mutations. Here, we report that glycosyltransferase 8 domain containing 1 (GLT8D1), induced by HIF-1α under a hypoxic niche, significantly correlates with a higher grade of glioma, and a worse clinical outcome. Depletion of GLT8D1 inhibits self-renewal of glioma stem cell (GSC) in vitro and represses tumor growth in glioma mouse models. GLT8D1 knockdown promotes cell cycle arrest at G2/M phase and cellular apoptosis with or without TMZ treatment. We reveal that GLT8D1 impedes CD133 degradation through the endosomal-lysosomal pathway by N-linked glycosylation and protein-protein interaction. Directly blocking the GLT8D1/CD133 complex formation by CD133N1~108 (referred to as FECD133), or inhibiting GLT8D1 expression by lercanidipine, suppresses Wnt/ß-catenin signaling dependent tumorigenesis both in vitro and in patient-derived xenografts mouse model. Collectively, these findings offer mechanistic insights into how hypoxia promotes GLT8D1/CD133/Wnt/ß-catenin signaling during glioma progression, and identify GLT8D1 as a potential therapeutic target in the future.

RETSAT Mutation Selected for Hypoxia Adaptation Inhibits Tumor Growth.

Hypoxia occurs not only in natural environments including high altitude, underground burrows and deep sea, but also in human pathological conditions, such as hypoxic solid tumors. It has been well documented that hypoxia related signaling pathway is associated with a poor clinical outcome. Our group has recently identified multiple novel genes critical for solid tumor growth comparing the genome-wide convergent/parallel sequence evolution of highland mammals. Among them, a single mutation on the retinol saturase gene (RETSAT) containing amino acid switch from glutamine (Q) to arginine (R) at the position 247 was identified. Here, we demonstrate that RETSAT is mostly downregulated in multiple types of human cancers, whose lower expression correlates with worse clinical outcome. We show that higher expression of RETSAT is positively associated with immune infiltration in different human cancers. Furthermore, we identify that the promoter region of RETSAT is highly methylated, which leads to its decreased expressions in tumor tissues comparing to normal tissues. Furthermore, we show that RETSAT knockdown promotes, while its overexpression inhibits, the cell proliferation ability of mouse embryonic fibroblasts (MEFs) and B16 in vitro. In addition, the mice carrying homozygous Q247R mutation (RETSATR/R) is more resistant to xenograft tumor formation, as well as DMBA/TPA induced cutaneous keratinocyte carcinoma formation, compared to littermate wild-type (RETSATQ/Q) mice. Mechanistic study uncovers that the oncogenic factor, the prolyl isomerase (PPIase) Pin1 and its related downstream signaling pathway, were both markedly repressed in the mutant mice compared to the wild-type mice. In summary, these results suggest that interdisciplinary study between evolution and tumor biology can facilitate identification of novel molecular events essential for hypoxic solid tumor growth in the future.

PirB functions as an intrinsic suppressor in hippocampal neural stem cells.

Neural stem cells play pivotal roles during prenatal development and throughout life. Here, we report that Paired immunoglobulin-like receptor B (PirB) functions as a suppressor during brain neurogenesis in the adult mouse. PirB expression increased with age during development, and its deficiency promoted neural stem cell proliferation and differentiation in vivo and in vitro. Furthermore, we detected an increase in Type 1 neural stem cells in PirB-deficient mice compared to their wild-type littermates. PirB deficiency promoted stemness marker gene expression of Sox2 and KLF4 by activating Akt1 phosphorylation. These findings suggest that PirB inhibits the self-renewal and differentiation capacities of neural stem cells. Thus, PirB may have the potential to serve as a therapeutic target for treatment of reduced neurogenesis in adults due to aging or other pathological conditions.

The role of m6A modification in the biological functions and diseases.

N6-methyladenosine (m6A) is the most prevalent, abundant and conserved internal cotranscriptional modification in eukaryotic RNAs, especially within higher eukaryotic cells. m6A modification is modified by the m6A methyltransferases, or writers, such as METTL3/14/16, RBM15/15B, ZC3H3, VIRMA, CBLL1, WTAP, and KIAA1429, and, removed by the demethylases, or erasers, including FTO and ALKBH5. It is recognized by m6A-binding proteins YTHDF1/2/3, YTHDC1/2 IGF2BP1/2/3 and HNRNPA2B1, also known as "readers". Recent studies have shown that m6A RNA modification plays essential role in both physiological and pathological conditions, especially in the initiation and progression of different types of human cancers. In this review, we discuss how m6A RNA methylation influences both the physiological and pathological progressions of hematopoietic, central nervous and reproductive systems. We will mainly focus on recent progress in identifying the biological functions and the underlying molecular mechanisms of m6A RNA methylation, its regulators and downstream target genes, during cancer progression in above systems. We propose that m6A RNA methylation process offer potential targets for cancer therapy in the future.

NCAPH is negatively associated with Mcl­1 in non­small cell lung cancer.

Lung cancer has a high mortality rate worldwide. Non­SMC condensin I complex subunit H (NCAPH) has been identified to be one of the regulatory subunits of the condensin I complex, which is essential for the correct packaging and segregation of chromosomes in eukaryotes. NCAPH is abnormally overexpressed in various types of cancer. A pro­survival member of the Bcl­2 family, myeloid cell leukemia sequence 1 (Mcl­1) is also frequently overexpressed in multiple cancers and is associated with poorer clinical outcomes for patients. The association of NCAPH and Mcl­1 proteins with the clinical and pathological features of non­small cell lung cancer (NSCLC) remains to be elucidated. In the current study, the positive percentage of NCAPH in the non­cancerous lung tissues was revealed to be higher compared with that in NSCLC. However, the positive percentage of Mcl­1 in the non­cancerous lung tissues was lower compared with NSCLC. In addition, NCAPH high­expression patients had a higher overall survival rate compared with patients exhibiting low expression, whereas the Mcl­1 high­expression group had a lower survival rate. Pairwise association in 260 cases of NSCLC revealed that overexpression of the NCAPH protein was negatively associated with Mcl­1 expression and vice versa. The results of multivariate Cox proportional hazard regression analysis also indicated that NCAPH and Mcl­1 demonstrated potential as distinct prognostic factors that may be used in NSCLC. The expression of NCAPH and Mcl­1 may be associated with, and act as distinct molecular marks for the prediction of a poor prognosis in patients with NSCLC.

Hypoxia and cancer related pathology.

Hypoxic environments occur normally at high altitude, or in underground burrows and in deep sea habitats. They also occur pathologically in human ischemia and in hypoxic solid tumors. Hypoxia in various cancer types and its related molecular mechanisms are associated with a poor clinical outcome. This review will discuss how hypoxia can influence two aspects of tumorigenesis, namely the direct, cell-intrinsic oncogenic effects, as well as the indirect effects on tumor progression mediated by an altered tumor microenvironment. We will also discuss recent progress in identifying the functional roles of hypoxia-related factors (HIFs), along with their regulators and downstream target genes, in cancer stem cells and therapy. Importantly, we propose, using convergent evolution schemes to identify novel biomarkers for both hypoxia adaptation and hypoxic solid tumors as an important strategy in the future.

PAQR4 promotes chemoresistance in non-small cell lung cancer through inhibiting Nrf2 protein degradation.

Purpose: Lung cancer is the leading cause of cancer related deaths worldwide. We have previously identified many differentially expressed genes (DEGs) from large scale pan-cancer dataset using the Cross-Value Association Analysis (CVAA) method. Here we focus on Progestin and AdipoQ Receptor 4 (PAQR4), a member of the progestin and adipoQ receptor (PAQR) family localized in the Golgi apparatus, to determine their clinical role and mechanism in the development of non-small cell lung cancer (NSCLC). Methods: The protein expression profile of PAQR4 was examined by IHC using tissue microarrays, and the effects of PAQR4 on cell proliferation, colony formation and xenograft tumor formation were tested in NSCLC cells. Real-time RT-PCR, co-immunoprecipitation (co-IP) and GST-pulldown assays were used to explore the mechanism of action of PAQR4. Results: We provided evidence showing that PAQR4 is increased in NSCLC cancer cell lines (A549, H1299, H1650, H1975, H358, GLC-82 and SPC-A1), and identified many mutations in PAQR4 in non-small cell lung cancer (NSCLC) tissues. We demonstrated that PAQR4 high expression correlates with a worse clinical outcome, and that its knockdown suppresses cell proliferation by inducing apoptosis. Importantly, overexpressed PAQR4 physically interacts with Nrf2 in NSCLC cells, blocking the interaction between Nrf2 and Keap1. Conclusion: Our results suggest that PAQR4 depletion enhances the sensitivity of cancerous cell to chemotherapy both in vitro and xenograft tumor formation in vivo, by promoting Nrf2 protein degradation through a Keap1-mediated ubiquitination process.

AN ADAPTIVE TRACKING ALGORITHM OF LUNG TUMORS IN FLUOROSCOPY USING ONLINE LEARNED COLLABORATIVE TRACKERS.

Accurate tracking of tumor movement in fluoroscopic video sequences is a clinically significant and challenging problem. This is due to blurred appearance, unclear deforming shape, complicate intra- and inter- fractional motion, and other facts. Current offline tracking approaches are not adequate because they lack adaptivity and often require a large amount of manual labeling. In this paper, we present a collaborative tracking algorithm using asymmetric online boosting and adaptive appearance model. The method was applied to track the motion of lung tumors in fluoroscopic sequences provided by radiation oncologists. Our experimental results demonstrate the advantages of the method.