RESUMO
MicroRNAs (miRNAs) are a class of small non-coding RNAs approximately 18-22 nucleotides in length, which play an important role in malignant transformation. The roles of miR-192 as an oncogene or tumor suppressor in solid tumors have been previously reported. However, little is known about the role of miR-192 in human acute myeloid leukemia. The results of the present study indicate that miR-192 is significantly downregulated in specimens from acute myeloid leukemia patients. Functional assays demonstrated that overexpression of miR-192 in NB4 and HL-60 cells significantly inhibited cell proliferation compared with that in control cells, and induced G0/G1 cell cycle arrest, cell differentiation, and apoptosis in vitro. Dual-luciferase reporter gene assays showed that miR-192 significantly suppressed the activity of a reporter gene containing the wild type 3'-UTR of CCNT2, but it did not suppress the activity of a reporter gene containing mutated 3'-UTR of CCNT2. QRT-PCR and Western blot assays showed that miR-192 significantly downregulated the expression of CCNT2 in human leukemia cells. Exogenous expression of CCNT2 attenuated the cell cycle arrest induced by miR-192 in NB4 and HL-60 cells. Collectively, miR-192 inhibits cell proliferation and induces G0/G1 cell cycle arrest in AML by regulating the expression of CCNT2.
Assuntos
Ciclo Celular/genética , Proliferação de Células/genética , Transformação Celular Neoplásica/genética , Ciclina T/genética , Ciclina T/fisiologia , Leucemia Mieloide Aguda/genética , Leucemia Mieloide Aguda/patologia , MicroRNAs/genética , MicroRNAs/fisiologia , Regiões 3' não Traduzidas/genética , Apoptose/genética , Pontos de Checagem do Ciclo Celular/genética , Regulação para Baixo , Expressão Gênica , Células HL-60 , HumanosRESUMO
Combined pulmonary fibrosis and emphysema (CPFE) is an "umbrella term" encompassing emphysema and pulmonary fibrosis, but its pathogenesis is not known. We established two models of CPFE in mice using tracheal instillation with bleomycin (BLM) or murine gammaherpesvirus 68 (MHV-68). Experimental mice were divided randomly into four groups: A (normal control, n=6), B (emphysema, n=6), C (emphysema+MHV-68, n=24), D (emphysema+BLM, n=6). Group C was subdivided into four groups: C1 (sacrificed on day 367, 7 days after tracheal instillation of MHV-68); C2 (day 374; 14days); C3 (day 381; 21days); C4 (day 388; 28days). Conspicuous emphysema and interstitial fibrosis were observed in BLM and MHV-68 CPFE mouse models. However, BLM induced diffuse pulmonary interstitial fibrosis with severely diffuse pulmonary inflammation; MHV-68 induced relatively modest inflammation and fibrosis, and the inflammation and fibrosis were not diffuse, but instead around bronchioles. Inflammation and fibrosis were detectable in the day-7 subgroup and reached a peak in the day-28 subgroup in the emphysema + MHV-68 group. Levels of macrophage chemoattractant protein-1, macrophage inflammatory protein-1α, interleukin-13, and transforming growth factor-ß1 in bronchoalveolar lavage fluid were increased significantly in both models. Percentage of apoptotic type-2 lung epithelial cells was significantly higher; however, all four types of cytokine and number of macrophages were significantly lower in the emphysema+MHV-68 group compared with the emphysema +BLM group. The different changes in pathology between BLM and MHV-68 mice models demonstrated different pathology subtypes of CPFE: macrophage infiltration and apoptosis of type-II lung epithelial cells increased with increasing pathology score for pulmonary fibrosis.
