Oncogenic and immunological roles of RACGAP1 in pan-cancer and its potential value in nasopharyngeal carcinoma.

A particular GTPase-activating protein called RACGAP1 is involved in apoptosis, proliferation, invasion, metastasis, and drug resistance in a variety of malignancies. Nevertheless, the role of RACGAP1 in pan-cancer was less studied, and its value of the expression and prognostic of nasopharyngeal carcinoma (NPC) has not been explored. Hence, the goal of this study was to investigate the oncogenic and immunological roles of RACGAP1 in various cancers and its potential value in NPC. We comprehensively analyzed RACGAP1 expression, prognostic value, function, methylation levels, relationship with immune cells, immune infiltration, and immunotherapy response in pan-cancer utilizing multiple databases. The results discovered that RACGAP1 expression was elevated in most cancers and suggested poor prognosis, which could be related to the involvement of RACGAP1 in various cancer-related pathways such as the cell cycle and correlated with RACGAP1 methylation levels, immune cell infiltration and reaction to immunotherapy, and chemoresistance. RACGAP1 could inhibit anti-tumor immunity and immunotherapy responses by fostering immune cell infiltration and cytotoxic T lymphocyte dysfunction. Significantly, we validated that RACGAP1 mRNA and protein were highly expressed in NPC. The Gene Expression Omnibus database revealed that elevated RACGAP1 expression was associated with shorter PFS in patients with NPC, and RACGAP1 potentially influenced cell cycle progression, DNA replication, metabolism, and immune-related pathways, resulting in the recurrence and metastasis of NPC. This study indicated that RACGAP1 could be a potential biomarker in pan-cancer and NPC.

Radioprotective efficacy of Astilbin in mitigating radiation-induced lung injury through inhibition of p53 acetylation.

Radiation-induced lung injury (RILI) is a common side effect in thoracic tumor patients undergoing radiotherapy. At present, there is no ideal radio-protective agent which is widely used in RILI treatment. Astilbin (AST), a bioactive flavonoid, exhibits various biological effects, including anti-inflammatory, antioxidant, and anti-fibrotic activities, which partly result from reducing oxidative stress and inflammation in various pathogenic conditions. However, the protective efficacy of AST to ameliorate RILI has not been reported. In this study, we employed network pharmacology, RNA sequencing, and experimental evaluation to reveal the effects and pharmacological mechanism of AST to treat RILI in vivo and in vitro. We observed that AST reduced radiation-induced apoptosis, DNA damage, inflammatory reactions, and the reactive oxygen species (ROS) level in human normal lung epithelial cells BEAS-2B. Further study showed that AST treatment significantly ameliorated RILI by reducing the radiation-induced pathology changes and inflammatory reaction of lung tissue in C57BL/6J mice. Mechanistically, the expression of epithelial-mesenchymal transition (EMT) markers and radiation-triggered acetylation of the p53 protein were alleviated by AST treatment. Furthermore, AST alleviated the acetylation of p53 after intervention of Trichostatin A (TSA). Our data indicate that AST can alleviate RILI by inhibiting inflammatory reactions and the EMT process through decreasing the expression of p53 acetylation. In conclusion, our study suggests that AST has great potential to be a new protective and therapeutic compound for RILI.

m6A demethylase FTO renders radioresistance of nasopharyngeal carcinoma via promoting OTUB1-mediated anti-ferroptosis.

Radiotherapy is a valid treatment for nasopharyngeal carcinoma (NPC), and radioresistance is the main cause of local NPC treatment failure. However, the underlying mechanisms and valuable markers of radioresistance for NPC remain have not been established. In this study, we observed that the m6A mRNA demethylase fat mass and obesity-associated protein (FTO) was significantly upregulated in radioresistant NPC tissues and cells relative to parental radiosensitive NPC tissues and cells. FTO enhances radioresistance by repressing radiation-induced ferroptosis in NPC. Mechanistically, FTO acts as an m6A demethylase to erase the m6A modification of the OTUB1 transcript and promote the expression of OTUB1, thereby inhibiting the ferroptosis of cells induced by radiation and finally triggering the radiotherapy resistance of NPC. Furthermore, our in vivo experiment results showed that the FTO inhibitor, FB23-2, and the ferroptosis activator, erastin, altered tumor responsiveness to radiotherapy in NPC cell lines and patient-derived xenografts. Our findings reveal, for the first time, that FTO enhances NPC radiotherapy resistance by withstanding radiation-induced ferroptosis, suggesting that FTO may serve as a potential therapeutic target and valuable prognostic biomarker in patients with NPC.

Potential Functions of the tRNA-Derived Fragment tRF-Gly-GCC Associated With Oxidative Stress in Radiation-Induced Lung Injury.

Objective: Transfer RNA-derived small RNAs (tsRNAs) are a novel type of non-coding RNA with various regulatory functions. They are associated with oxidative stress in various diseases, but their potential functions in radiation-induced lung injury (RILI) remain uncertain. Methods: To explore the role of tsRNAs in RILI, we used X-rays to irradiate human bronchial epithelial cells and examined the expression profile of altered tsRNAs by RNA sequencing and bioinformatics analysis. Sequencing results were verified by qRT-PCR. tsRNA functions were explored using several methods, including CCK-8, reactive oxygen species (ROS) assays, cell transfection, and western blotting. Results: Eighty-six differentially expressed tRNA-derived fragments (tRFs) were identified: 64 were upregulated, and 22 were downregulated. Among them, the regulation of tRF-Gly-GCC, associated with oxidative stress, may be mediated by the inhibition of cell proliferation, promotion of ROS production, and apoptosis in the occurrence and development of RILI. A Kyoto Encyclopedia of Genes and Genomes (KEGG) analysis suggested that the underlying molecular mechanism may involve the PI3K/AKT and the FOXO1 signaling pathways. Conclusion: Our findings provide new insights into the molecular mechanisms underpinning RILI, advancing the clinical prevention and treatment of this disease.

Construction of MicroRNA-mRNA Regulatory Network in the Molecular Mechanisms of Bleomycin-Induced Pulmonary Fibrosis.

Bleomycin is a common antitumor agent used to treat many different types of malignancies; however, its main side effect is pulmonary fibrosis. The mechanism of bleomycin-induced pulmonary fibrosis (BIPF) has not been fully elucidated. Therefore, to further explore the molecular mechanisms of BIPF, we screened for microRNA (miRNA) and mRNA expression obtained from BIPF samples from the Gene Expression Omnibus database. Subsequently, we identified the differentially expressed miRNAs and genes that overlapped with the differentially expressed miRNAs target genes, predicted by using the miRWalk database selected as a candidate. The candidate genes were visualized based on Gene Ontology and the Kyoto Encyclopedia of Genes and Genomes analyses. A protein-protein interaction network was constructed. Hub differentially expressed genes were selected and corresponding miRNAs to construct a miRNA-mRNA regulation network. Then, we chose three key miRNAs to study their regulatory relationship in bleomycin-induced pulmonary fibrosis. Finally, mouse lung epithelial cells TC-1 and MLE-12 were treated with bleomycin with qPCR to validate the results of three important hub genes and all key miRNAs. And dual-luciferase report experiment was carried out to verify the interaction of mmu-miR-1946a and serpina3n. The results revealed that the imbalance of matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) plays a pivotal role in the occurrence and development of BIPF. In addition, Serpina3n and mmu-miR-1946a were proved interaction and may be involved in the regulation of the balance between MMP-9 and TIMP-1. The experimental results also verify the analysis. Our findings provide new insights into the key mediators and pathways related to the molecular mechanisms of BIPF.

U-Shaped Association of Aspect Ratio and Single Intracranial Aneurysm Rupture in Chinese Patients: A Cross-Sectional Study.

Background: Previous studies have analyzed the association of aspect ratio (AR) on the ruptured intracranial aneurysm (IA), but the findings are inconclusive and controversial. Therefore, the study aimed to derive a more detailed estimation of this association between AR and ruptured IA in Chinese IA patients. Methods: The present work was a cross-sectional study. We retrospectively collected 1,588 Chinese patients with a single IA from January 2010 to November 2017. The relationship was examined between AR at diagnosis and ruptured IA. Covariates included data of demographics, morphological parameters, lifestyle habits, clinical features, and comorbidities. Binary logistic regression and two-piecewise linear models were used to analyze independent associations of AR with ruptured IA. Results: The results suggest that the association between AR and IA rupture was U-shaped. In the AR range of 1.08-1.99, the prevalence of IA rupture was 13% lower for each 0.1-unit increment in AR [odds ratio 0.87, 95% confidence interval (CI) 0.80-0.98]. Conversely, for every 0.1-unit increase in AR, the prevalence of IA rupture increased by ~3% (odds ratio 1.03, 95% CI 1.01-1.06) in the AR range of 3.42-4.08. Conclusion: The relationship between AR and ruptured IA was U-shaped, with the negative association at AR of 1.08-1.99 and positive association at AR of 3.42-4.08.

ABCC5 facilitates the acquired resistance of sorafenib through the inhibition of SLC7A11-induced ferroptosis in hepatocellular carcinoma.

Sorafenib is a first-line molecular-target drug for advanced hepatocellular carcinoma (HCC), and reducing sorafenib resistance is an important issue to be resolved for the clinical treatment of HCC. In the current study, we identified that ABCC5 is a critical regulator and a promising therapeutic target of acquired sorafenib resistance in human hepatocellular carcinoma cells. The expression of ABCC5 was dramatically induced in sorafenib-resistant HCC cells and was remarkably associated with poor clinical prognoses. The down-regulation of ABCC5 expression could significantly reduce the resistance of sorafenib to HCC cells. Importantly, activation of PI3K/AKT/NRF2 axis was essential for sorafenib to induce ABCC5 expression. ABCC5 increased intracellular glutathione (GSH) and attenuated lipid peroxidation accumulation by stabilizing SLC7A11 protein, which inhibited ferroptosis. Additionally, the inhibition of ABCC5 enhanced the anti-cancer activity of sorafenib in vitro and in vivo. These findings demonstrate a novel molecular mechanism of acquired sorafenib resistance and also suggest that ABCC5 is a new regulator of ferroptosis in HCC cells.

KCNQ1OT1 lncRNA affects the proliferation, apoptosis, and chemoresistance of small cell lung cancer cells via the JAK2/STAT3 axis.

BACKGROUND: Small cell lung cancer (SCLC) is a devastating and aggressive neuroendocrine carcinoma characterized by high cellular proliferation and early metastatic spread. Numerous studies have demonstrated that long noncoding RNAs (lncRNAs) can regulate tumor generation and development, including in SCLC. The current study aimed to assess the effect of the lncRNA, KCNQ1OT1, on the proliferation, apoptosis, and chemoresistance of SCLC and the potential underlying molecular mechanism. METHODS: Matched chemo-resistant and sensitive cells were applied to RNA isolation and followed by expression profiling by microarray analysis and subsequent quantitative polymerase chain reaction (qPCR) validation. Cell viability and apoptosis were determined by Cell Counting Kit-8 and flow cytometry to examine the chemoresistance and apoptosis of KCNQ1OT1 knockdown with lentivirus-mediated RNA interference. Furthermore, cell proliferation was studied by colony formation, and invasion and migration were tested by Transwell cell invasion and wound-healing assays, respectively. A tumor xenograft model was established to determine the role of KCNQ1OT1 in tumor growth and chemoresistance in response to KCNQ1OT1 knockdown in vivo. Western blot analysis, qPCR, and immunohistochemistry were used to detect the levels of messenger RNA (mRNA) Janus kinase 2 (JAK2)/signal transducer and activator of transcription 3 (STAT3) pathway-related markers. RESULTS: Higher expression of KCNQ1OT1 was detected in SCLC chemo-resistant verso chemo-sensitive cells. Knockdown of KCNQ1OT1 inhibited SCLC cell viability and cloning ability, hindered cell migration and invasion, induced apoptosis in vitro, and suppressed tumor growth and chemoresistance in vivo, by activating the JAK2/STAT3 signaling pathway. CONCLUSIONS: This is the first study to indicate that lncRNA KCNQ1OT1 promotes cell proliferation and invasion, and prevents apoptosis of SCLC by activating the JAK2/STAT3 pathway.

Up-Regulation of Glycogen Synthesis and Degradation Enzyme Level Maintained Myocardial Glycogen in Huddling Brandt's Voles Under Cool Environments.

Small mammals exhibit limited glucose use and glycogen accumulation during hypothermia. Huddling is a highly evolved cooperative behavioral strategy in social mammals, allowing adaptation to environmental cooling. However, it is not clear whether this behavior affects the utilization of glycogen in cold environments. Here, we studied the effects of huddling on myocardial glycogen content in Brandt's voles (Lasiopodomys brandtii) under a mild cold environment (15°C). Results showed that (1) Compared to the control (22°C) group (CON), the number of glycogenosomes more than tripled in the cool separated group (CS) in both males and females; whereas the number of glycogenosomes increased in females but was maintained in males in the cool huddling group (CH). (2) Glycogen synthase (GS) activity in the CS group remained unchanged, whereas glycogen phosphorylase (GYPL) activity decreased, which mediated the accumulation of glycogen content of the CS group. (3) Both GS and GYPL activity increased which may contribute to the stability of glycogen content in CH group. (4) The expression levels of glucose transporters GLUT1 and GLUT4 increased in the CS group, accompanied by an increase in glucose metabolism. These results indicate that the reduced glycogen degradation enzyme level and enhanced glucose transport may lead to an increase in myocardial glycogen content of the separated voles under cool environment; while the up-regulation of glycogen synthesis and degradation enzyme level maintained myocardial glycogen content in the huddling vole.

Inhibition of lncRNA KCNQ1OT1 Improves Apoptosis and Chemotherapy Drug Response in Small Cell Lung Cancer by TGF-ß1 Mediated Epithelial-to-Mesenchymal Transition.

PURPOSE: Drug resistance is one of the main causes of chemotherapy failure in patients with small cell lung cancer (SCLC), and extensive biological studies into chemotherapy drug resistance are required. MATERIALS AND METHODS: In this study, we performed lncRNA microarray, in vitro functional assays, in vivo models and cDNA microarray to evaluate the impact of lncRNA in SCLC chemoresistance. RESULTS: The results showed that KCNQ1OT1 expression was upregulated in SCLC tissues and was a poor prognostic factor for patients with SCLC. Knockdown of KCNQ1OT1 inhibited cell proliferation, migration, chemoresistance and promoted apoptosis of SCLC cells. Mechanistic investigation showed that KCNQ1OT1 can activate transforming growth factor-ß1 mediated epithelial-to-mesenchymal transition in SCLC cells. CONCLUSION: Taken together, our study revealed the role of KCNQ1OT1 in the progression and chemoresistance of SCLC, and suggested KCNQ1OT1 as a potential diagnostic and prognostic biomarker in SCLC clinical management.

Development and clinical application of nursing-sensitive indicators for midline catheterization care using evidence-based methods.

BACKGROUND: Midline catheters (MCs) have been widely applied in clinical settings as they can provide painless venous access, thus improving the quality of life and reducing medical costs. Nursing-sensitive indicators (NSIs) are real and effective measures of nursing quality. Using evidence-based methods, we established the NSIs of MC care, with an attempt to provide a basis for evaluating and monitoring nursing quality for MC use. METHODS: An electronic search was performed in 5 databases including China National Knowledge Infrastructure (CNKI), Chinese Scientific Journal Database (VIP), Wanfang Data, PubMed, and Web of Science to identify studies that evaluated nursing quality during MC use. Two evaluators independently selected literature, extracted data, and evaluated the risk of bias. According to the Donabedian's structure-process-outcome model, we divided the NSIs into 3 levels. RESULTS: The established NSIs for MC use included 3 indicators (i.e., structure indicators, process indicators, and outcome indicators), among which there were 3 level-2 indicators and 7 level-3 indicators at the structure level, 2 level-2 indicators and 9 level-3 indicators at the process level, and 5 level-2 indicators and 17 level-3 indicators at the outcome level. CONCLUSIONS: The established NSIs for MC use offer a set of objective criteria for evaluating nursing performance during MC use and will help to improve nursing quality control.

EPHA5 mutation predicts the durable clinical benefit of immune checkpoint inhibitors in patients with lung adenocarcinoma.

Immune checkpoint inhibitor (ICI) therapy has shown remarkable clinical benefit in lung adenocarcinoma (LUAD) patients. Genomic mutations may be applicable to predict the response to ICIs. Eph receptor A5 (EPHA5) is frequently mutated in breast cancer, lung cancer, and other tumors; however, its association with outcome in patients who receive immunotherapy remains unknown. In this study, we report that EPHA5 mutations were associated with increased tumor mutation burden (TMB), neoantigen load, levels of immune-related gene expression signatures, and enhanced tumor-infiltrating lymphocytes (TILs) in LUAD. LUAD patients with EPHA5 mutations in the immunotherapy cohort achieved a longer progression-free survival (PFS) time than patients with wild-type EPHA5. Immune response pathways were among the top enriched pathways in samples with EPHA5 mutations. In addition, patients with EPHA5 mutations tended to be more sensitive to certain targeted molecular inhibitors, including serdemetan, lox2, and PF1-1. Collectively, our results suggest that identifying mutations in the EPHA5 gene may provide insight into the genome-wide mutational burden and may serve as a biomarker to predict the immune response of patients with LUAD.

Kinesin family members KIF2C/4A/10/11/14/18B/20A/23 predict poor prognosis and promote cell proliferation in hepatocellular carcinoma.

Kinesin superfamily proteins (KIFs) comprise a family of molecular motors that transport membranous organelles and protein complexes in a microtubule- and ATP-dependent manner, with multiple roles in cancers. Little is known about the function of KIFs in hepatocellular carcinoma (HCC). Here, we investigate the roles of KIFs in the prognosis and progression of HCC. Upregulation of eight KIFs (KIF2C, KIF4A, KIF10, KIF11, KIF14, KIF18B, KIF20A, and KIF23) was found to be significantly associated with the tumor stage and pathological tumor grade of HCC patients. Additionally, a high expression of these eight KIFs was significantly associated with shorter overall survival (OS) and disease-free survival (DFS) in patients with HCC. Cox regression analysis showed the mRNA expression levels of these eight KIF members to be independent prognostic factors for worse outcomes in HCC. Moreover, a risk score model based on the mRNA levels of the eight KIF members effectively predicted the OS rate of patients with HCC. Additional experiments revealed that downregulation of each of the eight KIFs effectively decreased the proliferation and increased the G1 arrest of liver cancer cells in vitro. Taken together, these results indicate that KIF2C/4A/10/11/14/18B/20A/23 may serve as prognostic biomarkers for survival and potential therapeutic targets in HCC patients.

FGFRL1 affects chemoresistance of small-cell lung cancer by modulating the PI3K/Akt pathway via ENO1.

Fibroblast growth factor receptor-like 1 (FGFRL1), a member of the FGFR family, has been demonstrated to play important roles in various cancers. However, the role of FGFRL1 in small-cell lung cancer (SCLC) remains unclear. Our study aimed to investigate the role of FGFRL1 in chemoresistance of SCLC and elucidate the possible molecular mechanism. We found that FGFRL1 levels are significantly up-regulated in multidrug-resistant SCLC cells (H69AR and H446DDP) compared with the sensitive parental cells (H69 and H446). In addition, clinical samples showed that FGFRL1 was overexpressed in SCLC tissues, and high FGFRL1 expression was associated with the clinical stage, chemotherapy response and survival time of SCLC patients. Knockdown of FGFRL1 in chemoresistant SCLC cells increased chemosensitivity by increasing cell apoptosis and cell cycle arrest, whereas overexpression of FGFRL1 in chemosensitive SCLC cells produced the opposite results. Mechanistic investigations showed that FGFRL1 interacts with ENO1, and FGFRL1 was found to regulate the expression of ENO1 and its downstream signalling pathway (the PI3K/Akt pathway) in SCLC cells. In brief, our study demonstrated that FGFRL1 modulates chemoresistance of SCLC by regulating the ENO1-PI3K/Akt pathway. FGFRL1 may be a predictor and a potential therapeutic target for chemoresistance in SCLC.

Linc00173 promotes chemoresistance and progression of small cell lung cancer by sponging miR-218 to regulate Etk expression.

The functional effects of long noncoding RNAs (lncRNAs) in cancer have been widely recognized. However, there is little research on SCLC-related lncRNAs. Here, long intergenic nonprotein coding RNA 173 (Linc00173) was first shown to be involved in chemoresistance and progression of small-cell lung cancer (SCLC). We found that Linc00173 was highly expressed in SCLC chemoresistant cell lines, and promoted SCLC cells chemoresistance, proliferation, and migration-invasion. Animal studies validated that Linc00173 induced tumor chemoresistance and growth of SCLC in vivo. Moreover, Linc00173 upregulated Etk through functioning as a competitive endogenous RNA (ceRNA) by "sponging" miRNA-218 and led to the upregulation of GSKIP and NDRG1, resulting in the translocation of ß-catenin. Importantly, expression analysis revealed that both Linc00173 and Etk were upregulated in SCLC patient samples and exhibiting positive Linc00173/Etk correlation. High expression of Linc00173 closely correlated with chemoresistance, extensive stage, and shorter survival in SCLC patients. Collectively, our study illustrated a Linc00173-mediated process that facilitated chemoresistance and progression in SCLC, which might provide treatment strategy against SCLC.

Circular RNA cESRP1 sensitises small cell lung cancer cells to chemotherapy by sponging miR-93-5p to inhibit TGF-ß signalling.

Circular RNAs (circRNAs) are novel RNA molecules that play important roles in chemoresistance in different cancers, including breast and gastric cancers. However, whether circRNAs are involved in the response to chemotherapy in small cell lung cancer (SCLC) remains largely unknown. In this study, we observed that cESRP1 (circular RNA epithelial splicing regulatory protein-1) expression was significantly downregulated in the chemoresistant cells compared with the parental chemosensitive cells. cESRP1 enhanced drug sensitivity by repressing miR-93-5p in SCLC. Cytoplasmic cESRP1 could directly bind to miR-93-5p and inhibit the posttranscriptional repression mediated by miR-93-5p, thereby upregulating the expression of the miR-93-5p downstream targets Smad7/p21(CDKN1A) and forming a negative feedback loop to regulate transforming growth factor-ß (TGF-ß) mediated epithelial-mesenchymal transition. Furthermore, cESRP1 overexpression and TGF-ß pathway inhibition both altered tumour responsiveness to chemotherapy in an acquired chemoresistant patient-derived xenograft model. Importantly, cESRP1 expression was downregulated in SCLC patient tissues and was associated with survival. Our findings reveal, for the first time, that cESRP1 plays crucial a role in SCLC chemosensitivity by sponging miR-93-5p to inhibit the TGF-ß pathway, suggesting that cESRP1 may serve as a valuable prognostic biomarker and a potential therapeutic target in SCLC patients.

[Establishment of A Patient-derived Xenotransplantation Animal Model for Small Cell Lung Cancer and Drug Resistance Model].

BACKGROUND: Small cell lung cancer (SCLC) is characterized by poor differentiation, high malignancy and rapid growth fast, short double time, early and extensive metastatic malignancy. In clinical, chemotherapy is the main treatment method, while resistance to multiple chemotherapy drugs in six to nine months has been a major clinical challenge in SCLC treatment. Therefore, It has important clinical value to building SCLC aninimal model which is similar to patients with SCLC. Animal model of xenotransplantation (PDX) from the patients with small cell lung cancer can well retain the characteristics of primary tumor and is an ideal preclinical animal model. The study is aimed to establish SCLC PDX animal model and induce the chemoresistance model to help to study the mechanism of chemoresistance and individual treatment. METHODS: Fresh surgical excision or puncture specimens from SCLC patients were transplanted into B-NSGTM mice subcutaneous tissues with severe immunodeficiency in one hour after operation the B-NSGTM mice subcutaneous in 1 hour, and inject chemotherapy drugs intraperitoneally after its tumor growed to 400 mm³ with EP which is cisplatin 8 mg/kg eight days and etoposide 5 mg/kg every two days until 8 cycles. Measure the tumor volum and mice weights regularly, then re-engrafted the largest tumor and continue chemotherapy. RESULTS: Nine cases were conducted for B-NSG mice modeling. Three of nine cases could be engrafted to new B-NSG mice at least two generation. The SCLC PDX animal models have been established successfully. After adopting chemotherapy drugs, the chemoresistance PDX models have been established. High homogeneity was found between xenograft tumor and patient's tumor in histopathology, immunohistochemical phenotype (Syn, CD56, Ki67). CONCLUSIONS: The SCLC PDX animal model and the chemoresistance PDX animal model have been successfully constructed, the success rate is 33%, which provides a platform for the clinical research, seeking for biological markers and choosing individual treatment methods of SCLC.

Long noncoding RNA PCAT6 inhibits colon cancer cell apoptosis by regulating anti-apoptotic protein ARC expression via EZH2.

Prostate cancer-associated ncRNA transcript 6 (PCAT6) is a long intergenic noncoding RNA that is involved in the progression of prostate and lung cancer, acting as a potential diagnostic and prognostic biomarker in nonsmall cell lung cancer. However, little is known about PCAT6 expression and its clinical significance in colon cancer. Here, we aimed to investigate the clinical significance of PCAT6 in colon cancer and its underlying mechanism. The expression of PCAT6 was analyzed in colon cancer tissues using public databases, and a series of in vitro and in vivo experiments was performed to investigate the biological functions of PCAT6 in colon cancer cells and the underlying mechanisms. Our results demonstrated that PCAT6 was upregulated in colon cancer tissues compared with that in noncancerous tissues, correlating with poorer clinical stages and a worse survival status. In vitro and in vivo experiments illustrated PCAT6 promoted cell growth and inhibited cell apoptosis in colon cancer. Mechanistically, PCAT6 enhanced the coenrichment of EZH2 and H3K4me3 at the apoptosis repressor with caspase recruitment domain (ARC) genomic region, promoting the transcriptional activity of ARC. Our data highlighted that PCAT6 acts as a key activator of ARC expression by forming a complex with EZH2, inhibiting cell apoptosis and contributing to colon cancer progression. These findings elucidated that PCAT6 may be a novel prognostic predictor and therapeutic target of colon cancer.

Etk Interaction with PFKFB4 Modulates Chemoresistance of Small-cell Lung Cancer by Regulating Autophagy.

Purpose: Epithelial and endothelial tyrosine kinase (Etk), also known as bone marrow X kinase (Bmx), was found to be critical in modulating the chemoresistance of small-cell lung cancer (SCLC) in our preliminary study. However, the molecular mechanisms of Etk in SCLC chemoresistance remain poorly understood.Experimental Design: We determined correlation of Etk with autophagy in SCLC. And direct inhibition of autophagy was performed to validate its effect on chemoresistance. Coimmunoprecipitation (co-IP) and GST-pull down experiments were conducted to verify the interaction of Etk and PFKFB4, after a microarray analysis. In vitro and in vivo gain or loss-of-function analyses and evaluation of PFKFB4 expression in SCLC specimens, were done to validate its role in chemoresistance. Ibrutinib was administrated in SCLC cells to verify its synergistic anti-tumor effect with chemotherapy using preclinical models including a PDX model.Results: Downregulation of Etk suppressed autophagy in chemoresistant SCLC cells, and direct inhibition of autophagy sensitized cells to chemotherapy. PFKFB4 (6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 4) was identified as a downstream target of Etk and an Etk-interacting protein, which promoted chemoresistance in SCLC and was associated with poor therapeutic response and prognosis. Furthermore, ibrutinib was found to exhibit a synergistic anti-tumor effect with chemotherapy in targeting Etk.Conclusions: Our results demonstrated for the first time that Etk interacts with PFKFB4 to promote SCLC chemoresistance through regulation of autophagy. Aberrant Etk and PFKFB4 can be predictive factors for the chemotherapy response as well as potential therapeutic targets in SCLC. Clin Cancer Res; 24(4); 950-62. ©2017 AACR.