Metastasis‐associated lung adenocarcinoma transcript 1 (malat1) is an oncogenic long non‐coding RNA (lncRNA) which has been proven to be associated with various types of tumors. Transcription factor specificity protein 1 (SP1) is overexpressed in many types of cancers. Previously, we observed that malat1 expression level is regulated by SP1 in lung cancer. In the present study, we found that transfection of expression construct of malat1 5′ end fragment M5 enhances stability and transcriptional activity of SP1. Various SP1 target genes are also upregulated following overexpression of malat1 M5 in lung adenocarcinoma cells. We also showed that malat1 M5 interacts with the C‐terminal domain of SP1 by RNA immunoprecipitation (RIP) assay coupled with UV cross‐linking. Malat1‐SP1 association results in increase of SP1 stability. In turn, SP1 promotes malat1 transcription, thus forming a positive feedback loop. In conclusion, our data show that in lung adenocarcinoma cells, malat1 interacts with SP1 protein and promotes SP1‐mediated transcriptional regulation of SP1 target genes.

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Aim: Long noncoding RNAs (lncRNAs) are key mediators with a wide range of pathophysiological functions, but their role in human hepatocellular carcinoma (HCC) is still unclear.Methods: An unbiased microarray study evaluated a novel lncRNA, HClnc1, that is linked to the development of HCC. In vitro cell proliferation assays and an in vivo xenotransplanted HCC tumor model were performed to determine its functions, followed by antisense oligo-coupled mass spectrometry to identify HClnc1-interacting proteins. To study relevant signaling pathways, in vitro experiments were performed, including chromatin isolation by RNA purification, RNA immunoprecipitation, luciferase, and RNA pull-down assay.Results: HClnc1 levels were considerably greater in patients with advanced tumor-node-metastatic stages, and it was found to be inversely connected to survival rates. Moreover, the proliferative and invasive potential of the HCC cells was attenuated by HClnc1 RNA knockdown in vitro, while HCC tumor growth and metastasis were found to be reduced in vivo. HClnc1 interacted with pyruvate kinase M2 (PKM2) to prevent its degradation and thus facilitated aerobic glycolysis and PKM2-STAT3 signaling.Conclusions: HClnc1 is involved in a novel epigenetic mechanism of HCC tumorigenesis and PKM2 regulation. HClnc1 is not only a more accurate prognostic indicator of HCC but also a potential therapeutic target for HCC treatment.

PAX5, a member of the paired box gene family of transcription factors, is a B-cellspecific activator protein that plays important roles during B lymphopoiesis. Two putative PAX5 binding sites in the human GINS1 promoter region were identified.EMSA, ChIP and luciferase assay showed that PAX5 functions as a positive transcription factor for GINS1 expression. Furthermore, coordinated expression of PAX5 and GINS1 was observed in mice B cells under physiological conditions and LPS stimulation situations. A similar pattern was also observed in human DLBCL cell lines under differentiation-inducing conditions. In addition, both PAX5 and GINS1 were highly expressed and significantly correlated in DLBCL specimens and cell lines. These findings suggested that dysregulation of PAX5 played an extremely important role in controlling the universal phenomenon of tumor progression through increased expression of GINS1 in DLBCL. In addition, circ1857 that was generated using back splicing of PAX5 pre-mRNA could further stabilize GINS1 mRNA, modulate GINS1 expression and promote lymphoma progression. To the best of our knowledge, this report is the first to demonstrate the role of GINS1 in DLBCL progression, and the mechanism of GINS1 upregulation using both circ1857 and PAX5 in DLBCL was revealed. Our results suggested that GINS1 may be a possible therapeutic target for DLBCL.