Integrated high-throughput analysis identifies super enhancers associated with chemoresistance in SCLC.

BACKGROUND: Chemoresistance is a primary clinical challenge for the management of small cell lung cancer. Additionally, transcriptional regulation by super enhancer (SE) has an important role in tumor evolution. The functions of SEs, a key class of noncoding DNA cis-regulatory elements, have been the subject of many recent studies in the field of cancer research. METHODS: In this study, using chromatin immunoprecipitation-sequencing and RNA-sequencing (RNA-seq), we aimed to identify SEs associated with chemoresistance from H69AR cells. Through integrated bioinformatics analysis of the MEME chip, we predicted the master transcriptional factors (TFs) binding to SE sites and verified the relationships between TFs of SEs and drug resistance by RNA interference, cell counting kit 8 assays, quantitative real-time reverse transcription polymerase chain reaction. RESULTS: In total, 108 SEs were screened from H69AR cells. When combining this analysis with RNA-seq data, 45 SEs were suggested to be closely related to drug resistance. Then, 12 master TFs were predicted to localize to regions of those SEs. Subsequently, we selected forkhead box P1 (FOXP1), interferon regulatory factor 1 (IRF1), and specificity protein 1 (SP1) to authenticate the functional relationships of master TFs with chemoresistance via SEs. CONCLUSIONS: We screened out SEs involved with drug resistance and evaluated the functions of FOXP1, IRF1, and SP1 in chemoresistance. Our findings established a large group of SEs associated with drug resistance in small cell lung cancer, revealed the drug resistance mechanisms of SEs, and provided insights into the clinical applications of SEs.

A long non-coding RNA HOTTIP expression is associated with disease progression and predicts outcome in small cell lung cancer patients.

BACKGROUND: Despite progress in treatment of small cell lung cancer (SCLC), the biology of the tumor still remains poorly understood. Recently, we globally investigated the contributions of lncRNA in SCLC with a special focus on sponge regulatory network. Here we report lncRNA HOTTIP, which is specifically amplified in SCLC, is associated with SCLC proliferation and poor prognosis of patients. METHODS: RT-qPCR was used to investigate the expression of HOTTIP in SCLC tissues and cell lines. The role of HOTTIP in SCLC cell proliferation was demonstrated by CCK8 assay, colony formation assay, flow cytometry analysis and in vivo SCLC xenograft model in nude mice through HOTTIP loss- and gain-of-function effects. Western blot assay was used to evaluate gene expression in cell lines at protein level. RNA pull-down, Mass spectrometry and RNA binding protein immunoprecipitation (RIP) were performed to confirm the molecular mechanism of HOTTIP involved in SCLC progression. RESULTS: We found that HOTTIP was overexpressed in SCLC tissues, and its expression was correlated with the clinical stage and the shorter survival time of SCLC patients. Moreover, HOTTIP knockdown could impair cell proliferation, affect the cell cycle and inhibit tumor growth of mice, while HOTTIP overexpression might enhance cell proliferation and cell cycle in vitro and in vivo. Mechanistic investigations showed that HOTTIP functions as an oncogene in SCLC progression by sponging miR-574-5p and affecting the expression of polycomb group protein EZH1. CONCLUSIONS: Overall, we identified that HOTTIP was involved in SCLC tumorigenesis through the ceRNA network "HOTTIP/miR-574-5p/EZH1". Our findings not only illuminate how HOTTIP confers an oncogenic function in SCLC pathogenesis, but also underscore a novel gene expression governing hallmarks in the disease.

[Effects of Icariin on ovariectomized osteoporotic rats].

OBJECTIVE: To observe the effects of Icariin on ovariectomized osteoporotic rats. METHODS: Female Wistar rats were ovariectomized and administered different dosage of Icariin and 17beta-estradiol for eight weeks. Bone mineral density (BMD), indexes of biomechanics and bone metabolism-associated biochemical markers were measured. RESULTS: Icariin increased the BMD, maximum load and flexural rigidity in the osteoporotic rats. The activities of serum tartrate-resistant acid phosphatase (TRACP) and bone alkaline phosphatase (BALP) were decreased in the Icraiin-fed ovariectomized rats. CONCLUSION: Icariin 225mg/kg per day could increase the BMD and improve indexes of bone biomechanics in ovariectomized osteoporotic rats. It was effective in preventing bone loss induced by ovariectomy.