RESUMO
Colorectal cancer (CRC), the third most common cancer worldwide, poses a threat to human life. However, its underlying mechanism is unclear and no satisfactory treatment is available. The present study aimed to investigate the role of circular RNA argininosuccinate synthase 1 (circASS1) in CRC cells and tissues to identify the potential mechanism underlying the pathogenesis of CRC. The expression of circASS1 in CRC cells and tissues was determined by reverse transcription-quantitative PCR. Following circASS1 overexpression in HT29 cells, cell viability, colony formation and apoptosis were measured using MTT, colony formation and TUNEL assays, respectively. Cell invasion and migration were also assessed. After confirming the associations among circASS1, microRNA (miR)-1269a and vasohibin 1 (VASH1), the characteristics of the HT29 cell line were assessed by performing the aforementioned assays. circASS1 expression was decreased in CRC cells and tissues, and circASS1 overexpression suppressed CRC cell proliferation, invasion and migration. circASS1 adsorbed miR-1269a and regulated its expression, and VASH1 was a target protein of miR-1269a. circASS1 overexpression decreased cell proliferation, invasion and migration, but enhanced cell apoptosis in HT29 cells, which was reversed by co-transfection with miR-1269a mimic or short hairpin RNA-VASH1. In conclusion, circASS1 overexpression inhibited CRC cell proliferation, invasion and migration by regulating miR-1269a/VASH1, which indicated a potential molecular mechanism underlying the pathogenesis of CRC.
RESUMO
MicroRNAs (miRNAs) are a group of small noncoding RNA molecules, which serve an important function in the development of multidrug resistance in cancer through the posttranscriptional regulation of gene expression and RNA silencing. In the present study, the functional effects of miR197 were analyzed in chemoresistant gastric cancer cells. Low expression levels of miR197 were observed in the fluorouracil (5FU)resistant gastric cell line SGC7901/5FU when compared with those in the parental gastric cell line SGC7901. Overexpression of miR197 in SGC7901/5FU cells was identified to partially restore 5FU sensitivity. miRNA target prediction algorithms suggested that mitogenactivated protein kinase 1 (MAPK1) is a candidate target gene for miR197. A luciferase reporter assay confirmed that miR197 led to silencing of the MAPK1 gene by recognizing and then specifically binding to the predicted site of the MAPK1 mRNA 3'untranslated region. When miR197 was overexpressed in SGC7901 cells, the protein levels of MAPK1 were downregulated. Furthermore, MAPK1 knockdown significantly increased the growth inhibition rate of the SGC7901/5FU cells compared with those in the control group. These results indicated that miR197 may influence the sensitivity of 5FU treatment in a gastric cancer cell line by targeting MAPK1.
Assuntos
Antineoplásicos/farmacologia , Resistencia a Medicamentos Antineoplásicos/genética , Fluoruracila/farmacologia , Mucosa Gástrica/efeitos dos fármacos , Regulação Neoplásica da Expressão Gênica , MicroRNAs/genética , Proteína Quinase 1 Ativada por Mitógeno/genética , Regiões 3' não Traduzidas , Algoritmos , Sequência de Bases , Sítios de Ligação , Linhagem Celular Tumoral , Biologia Computacional , Mucosa Gástrica/metabolismo , Mucosa Gástrica/patologia , Inativação Gênica , Genes Reporter , Humanos , Luciferases/genética , Luciferases/metabolismo , MicroRNAs/metabolismo , Proteína Quinase 1 Ativada por Mitógeno/antagonistas & inibidores , Proteína Quinase 1 Ativada por Mitógeno/metabolismo , Dados de Sequência Molecular , RNA Interferente Pequeno/genética , RNA Interferente Pequeno/metabolismo , Transdução de SinaisRESUMO
Associations of P16, MGMT, hMLH1 and hMLH2 with gastric cancer and their relation with MTHFR status in gastric patients who were confirmed with pathological diagnosis were assessed. Aberrant DNA methylation of P16, MGMT, hMLH1 and hMLH2 and polymorphisms of MTHFR C677T were assayed. The proportional DNA hypermethylation in P16, MGMT, hMLH1 and hMLH2 in cancer tissues was significantly higher than in remote normal-appearing tissues. DNA hypermethylation of P16 and MGMT was correlated with the T and N stages. Individuals with homozygotes (TT) of MTHFR C677T had significant risk of hypermethylation of MGMT in cancer tissues [OR (95% CI)= 3.47(1.41-7.93)]. However, we did not find association between polymorphism in MTHFR C677T and risk of hypermethylation in P16, MGMT, hMLH1 and hMLH2 genes either in cancer or remote normal-appearing tissues. Aberrant hypermethylation of P16, MGMT, hMLH1 and hMLH2 could be predictive of gastric cancer.
