RESUMEN
Retroelements (REs) had been considered 'Junk' until the encyclopedia of DNA elements (ENCODE) project demonstrated that most genome is functional. Although the function of retroelements has been reported in diverse cancers including human breast cancer (HBC) and subtypes, only a few studies have suggested the putative functions of REs via their random genome integration. A canine mammary tumor (CMT) has been highlighted due to the similarities in molecular and pathophysiology with HBC. This study investigated the putative roles of REs common in both HBC and CMT. The human LINE and HERV-K sequences harbor many miRNAs responsive elements (MREs) for tumor-suppressive miRNA such as let-7. We also observed that various MREs are exist in the ERV and LINE highly expressed in the transcriptome data of CMT as well as HBC sets. MREs against miR-126 were highly expressed in both HBC and CMT while the levels of miR-126 were down-regulated. Oppositely, the expression of miR-126 target genes was significantly up-regulated in the cancers. Moreover, cancer patients with an increased level of miR-126 showed better overall survival. The expression of ENPP5, a putative miR-126 target gene, was downregulated by miR-126 mimic. Importantly, overexpression of LINE fragment significantly suppressed miR-126 function on the target gene expression. We propose the functional role of REs expression in tumorigenesis as competing endogenous RNAs (ceRNA) against tumor-suppressive miRNAs. This study provided pieces of evidence that LINE expression, even partial and fragmented, have a regulatory function in ENPP5 gene expression via the competition with miR-126.
Asunto(s)
Neoplasias de la Mama , Neoplasias Mamarias Animales , MicroARNs , Retroelementos , Animales , Perros , Femenino , Humanos , Neoplasias de la Mama/patología , Línea Celular Tumoral , Regulación Neoplásica de la Expresión Génica , Neoplasias Mamarias Animales/genética , MicroARNs/genética , Retroelementos/genética , TranscriptomaRESUMEN
Acquired resistance to tamoxifen (TAM) is a serious therapeutic problem in breast cancer patients. We have shown that Pin1, a peptidyl prolyl isomerase, is consistently overexpressed in TAM-resistant MCF-7 cells (TAMR-MCF-7 cells) and plays a key role in the enhanced angiogenic potential of TAMR-MCF-7 cells. In the present study, we focused on signaling pathways for Pin1 up-regulation in TAMR-MCF-7 cells. Relative to MCF-7 cells, Pin1 gene transcription and E2 transcription factor1 (E2F1) expression were enhanced in TAMR-MCF-7 cells. E2F1 siRNA significantly reduced both the protein expression and the promoter transcriptional activity of Pin1. Activities of phosphatidylinositol 3-kinase (PI3K), extracellular signal-regulated kinase (ERK) and p38 kinase were all higher in TAMR-MCF-7 cells than in control MCF-7 cells and the enhanced Pin1 and E2F1 expression in TAMR-MCF-7 cells was reversed by inhibition of PI3K or p38 kinase. Moreover, the higher production of vascular endothelial growth factor (VEGF) in TAMR-MCF-7 cells was significantly diminished by suppression of PI3K or p38 kinase. These results suggest that Pin1 overexpression and subsequent VEGF production in TAMR-MCF-7 cells are mediated through PI3-kinase or p38 kinase-dependent E2F1 activation.
Asunto(s)
Neoplasias de la Mama , Resistencia a Antineoplásicos , Factor de Transcripción E2F1/metabolismo , Regulación Neoplásica de la Expresión Génica , Isomerasa de Peptidilprolil/metabolismo , Fosfatidilinositol 3-Quinasas/metabolismo , Tamoxifeno/farmacología , Factor A de Crecimiento Endotelial Vascular/metabolismo , Proteínas Quinasas p38 Activadas por Mitógenos/metabolismo , Antineoplásicos Hormonales/farmacología , Antineoplásicos Hormonales/uso terapéutico , Western Blotting , Neoplasias de la Mama/tratamiento farmacológico , Neoplasias de la Mama/genética , Neoplasias de la Mama/metabolismo , Línea Celular Tumoral , Factor de Transcripción E2F1/genética , Ensayo de Inmunoadsorción Enzimática , Femenino , Silenciador del Gen/efectos de los fármacos , Genes Reporteros , Humanos , Luciferasas/análisis , Peptidilprolil Isomerasa de Interacción con NIMA , Isomerasa de Peptidilprolil/genética , Fosfatidilinositol 3-Quinasas/genética , ARN Interferente Pequeño/genética , ARN Interferente Pequeño/farmacología , Transducción de Señal , Tamoxifeno/uso terapéutico , Regulación hacia Arriba , Factor A de Crecimiento Endotelial Vascular/genética , Proteínas Quinasas p38 Activadas por Mitógenos/genéticaRESUMEN
Neointima, defined as abnormal growth of the intimal layer of blood vessels, is believed to be a critical event in the development of vascular occlusive disease. Although resveratrol's inhibitory effects on proliferation and migration of vascular smooth muscle cells has been reported, its activity on neointimal formation is still unclear. Oral administration of trans-resveratrol significantly suppressed intimal hyperplasia in a wire-injured femoral artery mouse model. In cultured vascular smooth muscle cells, trans-resveratrol inhibited platelet-derived growth factor-stimulated DNA synthesis and cell proliferation with down-regulation of cyclin D and pRB. Moreover, platelet-derived growth factor-induced production of reactive oxygen species was inhibited by trans-resveratrol and the compound induced heme oxygenase-1 (HO-1). The anti-proliferative activity of trans-resveratrol was reversed by an HO-1 inhibitor, ZnPPIX. Subcellular fractionation and reporter gene analyses revealed that trans-resveratrol increased the level of nuclear Nrf2 and antioxidant response element reporter activity, and that these were essential for the induction of HO-1. Trans-resveratrol also enhanced the activities of phosphatidyl inositol 3-kinase and extracellular signal regulated kinase, and phosphatidyl inositol 3-kinase was required for Nrf2/antioxidant response element-dependent HO-1 induction. These data have significant implications for the elucidation of the pharmacological mechanism by which trans-resveratrol prevents vascular occlusive diseases.