The circular RNA circ-ERBIN promotes growth and metastasis of colorectal cancer by miR-125a-5p and miR-138-5p/4EBP-1 mediated cap-independent HIF-1α translation.

BACKGROUND: Circular RNA (circRNAs) and hypoxia have been found to play the key roles in the pathogenesis and progression of cancer including colorectal cancer (CRC). However, the expressions and functions of the specific circRNAs in regulating hypoxia-involved CRC metastasis, and the circRNAs that are relevant to regulate HIF-1α levels in CRC remain elusive. METHODS: qRT-PCR was used to detect the expression of circRNAs and mRNA in CRC cells and tissues. Fluorescence in situ hybridization (FISH) was used to analyze the location of circ-ERBIN. Function-based experiments were performed using circ-ERBIN overexpression and knockdown cell lines in vitro and in vivo, including CCK8, colony formation, EdU assay, transwell, tumor growth and metastasis models. Mechanistically, luciferase reporter assay, western blots and immunohistochemical stainings were performed. RESULTS: Circ-Erbin was highly expressed in the CRC cells and Circ-Erbin overexpression facilitated the proliferation, migration and metastasis of CRC in vitro and in vivo. Notably, circ-Erbin overexpression significantly promoted angiogenesis by increasing the expression of hypoxia induced factor (HIF-1α) in CRC. Mechanistically, circ-Erbin accelerated a cap-independent protein translation of HIF-1α in CRC cells as the sponges of miR-125a-5p and miR-138-5p, which synergistically targeted eukaryotic translation initiation factor 4E binding protein 1(4EBP-1). CONCLUSIONS: Our findings uncover a key mechanism for circ-Erbin mediated HIF-1α activation by miR-125a-5p-5p/miR-138-5p/4EBP-1 axis and circ-ERBIN is a potential target for CRC treatment.

NSD2 circular RNA promotes metastasis of colorectal cancer by targeting miR-199b-5p-mediated DDR1 and JAG1 signalling.

Liver metastasis is the main cause of death in patients with colorectal cancer (CRC). Here, we searched for CRC metastasis-associated circular RNA in a mouse model of liver metastasis of CRC by using RNA (transcriptome)-sequencing. We identified a novel and conserved circular RNA, circ-NSD2, functioning as a promoter of CRC metastasis. Circ-NSD2 expression was elevated in CRC tissues and was markedly increased in advanced stages or metastatic tumours of CRC patients. Gain-of-function and loss-of-function experiments demonstrated that circ-NSD2 promoted migration and metastasis of CRC in vitro and in vivo. Mechanistically, circ-NSD2 acted as a sponge for the tumour suppressor miR-199b-5p and activated DDR1 (discoidin domain receptor tyrosine kinase 1) and JAG1 (Jagged 1) genes, which synergistically helped with cell-matrix interaction, migration and metastasis of CRC cells. Taken together, our findings highlight a novel oncogenic function of circ-NSD2 and uncover a key mechanism for the circ-NSD2/miR-199b-5p/DDR1/JAG1 axis in CRC metastasis, which may serve as a prognostic factor and therapeutic target for antimetastatic therapy in CRC patients. Copyright © 2019 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

SIRT1 suppresses colorectal cancer metastasis by transcriptional repression of miR-15b-5p.

The class III deacetylase sirtuin 1 (SIRT1), a member of the sirtuin family proteins, plays a key role in many types of cancers including colorectal cancer (CRC). Here we report that SIRT1 suppressed CRC metastasis in vitro and in vivo as a negative regulator for miR-15b-5p transcription. Mechanistically, SIRT1 impaired regulatory effects of activator protein (AP-1) on miR-15b-5p trans-activation through deacetylation of AP-1. Importantly, acyl-CoA oxidase 1 (ACOX1), a key enzyme of the fatty acid oxidation (FAO) pathway, was found as a direct target for miR-15b-5p. SIRT1 expression was positively correlated with ACOX1 expression in CRC cells and in xenografts. Moreover, ACOX1 overexpression attenuated the augmentation of migration and invasion of CRC cells by miR-15b-5p overexpression. In conclusion, our study demonstrated a functional role of the SIRT1/miR-15b-5p/ACOX1 axis in CRC metastasis and suggested a potential target for metastatic CRC therapy.

Dicer suppresses cytoskeleton remodeling and tumorigenesis of colorectal epithelium by miR-324-5p mediated suppression of HMGXB3 and WASF-2.

Emerging evidence indicates that microRNAs, a class of small and well-conserved noncoding RNAs, participate in many physiological and pathological processes. RNase III endonuclease DICER is one of the key enzymes for microRNA biogenesis. Here, we found that DICER was downregulated in tumor samples of colorectal cancer (CRC) patients at both mRNA and protein levels. Importantly, intestinal epithelial cell (IEC)-specific deletion of Dicer mice got more tumors after azoxymethane and dextran sulfate sodium (DSS) administration. Interestingly, IEC-specific deletion of Dicer led to severe chronic inflammation and epithelium layer remodeling in mice with or without DSS administration. Microarray analysis of 3 paired Dicer deletion CRC cell lines showed that miR-324-5p was one of the most significantly decreased miRNAs. In the intestinal epithelium of IEC-specific deletion of Dicer mice, miR-324-5p was also found to be markedly reduced. Mechanistically, miR-324-5p directly bound to the 3'untranslated regions (3'UTRs) of HMG-box containing 3 (HMGXB3) and WAS protein family member 2 (WASF-2), two key proteins participated in cell motility and cytoskeleton remodeling, to suppress their expressions. Intraperitoneal injection of miR-324-5p AgomiR (an agonist of miR-324-5p) curtailed chronic inflammation and cytoskeleton remodeling of colorectal epithelium and restored intestinal barrier function in IEC-specific deletion of Dicer mice induced by DSS. Therefore, our study reveals a key role of a DICER/miR-324-5p/HMGXB3/WASF-2 axis in tumorigenesis of CRC by regulation of cytoskeleton remodeling and maintaining integrity of intestinal barriers.

Epidermal growth factor receptor gene amplification and protein overexpression in basal-like carcinoma of the breast.

AIMS: Epidermal growth factor receptor (EGFR) is frequently expressed in basal-like breast cancer (BLBC). The aim of this study was to evaluate their correlation as detected by immunohistochemistry (IHC) or fluorescence in-situ hybridization (FISH). METHODS AND RESULTS: IHC for oestrogen receptor (ER), progesterone receptor (PR), human epidermal growth factor receptor (HER) 2, cytokeratin (CK) 5/6 and EGFR, and FISH for EGFR amplification, were performed in 59 cases of BLBC. EGFR IHC results were scored semiquantitatively, and compared with its gene amplification status. ER, PR and HER2 were negative in all cases, whereas 35 and 55 cases were positive for CK5/6 and EGFR. For EGFR IHC, 20, 11, 11 and 17 cases showed a negative, a low, an intermediate or a high staining level, respectively, and seven cases showed gene amplification by FISH, with two, 19, 11 and 20 cases showing balanced monosony, disomy, trisomy, and polysomy respectively. Immunohistochemical expression in gene-amplified tumours was significantly higher than in those without amplification, including balanced polysomy tumours. EGFR immunohistochemical expression also correlated with the EGFR/chromosome 7 ratio. High sensitivity (86%) and negative predictive value (98%) were achieved with high-level immunohistochemical expression as a cut-off to predict gene amplification. CONCLUSIONS: High-level EGFR immunohistochemical expression correlated with and predicted EGFR amplification, and may be used as a screening method to exclude gene amplification.

[Jointed estrogenic activities of bisphenol A and three of its analogs].

The combined effect of environmental endocrine disruptors (EEDs) is one of the hottest topics. The estrogenic activities of BPA, BPAF, BPAP, BPF were tested based on recombinant gene yeast assay. Six mixtures were designed based on the result of the test,each of which had an equitoxic ratio ray (EC10 or EC50). The EC50 values are 6.81 x 10(-6) mol x L(-1), 7.44 x 10(-7) mol x L(-1), 1.43 x 10(-5) mol x L(-1), 7.52 x 10(-6) mol x L(-1) for BPA, BPAF, BPAP and BPF respectively,which reveals that the estrogenic activities order among the four bisphenols was BPAF> BPA> BPF> BPAP. The experiment shows that when BPA mixes with BPAF, BPAP and BPF in different ratios individually, different combination effects are produced. It reveals that the combined ratios of the components may affect the combined effect. The dose addition model and the independent action model are used to identify the combined effect. They are testified to be more intuitionistic and more comprehensive than other joint effect indices.