RESUMO
Despite the great progress in recent years, many aspects of the pathogenesis and progression of breast cancer remain unclear. A better understanding on the molecular mechanisms underlying metastasis and recurrence is crucial to improve the treatment of this lethal disease. MCF-7 cells were xenografted into mice until visible tumors developed, and the cells from tumor tissue and adjacent normal tissue were cultured with 3 passages as mass tumor (MT) cells and invasive tumor (IT) cells, respectively. Microarray analysis was performed to detect several viable microRNAs in these 2 types of cells. Further, miR-30 knockdown was used to investigate its role in tumor aggression. Relative levels of miR-30 were significantly higher in IT cells than MT cells. Knockdown of miR-30 in both MT and IT cells lowered cell proliferation and cell invasion abilities, and thus increased the survival time of mice xenografted with tumor cells. This study suggested that the knockdown of miR-30 decreased proliferation and invasion of carcinoma cells, giving rise to the potential of miR-30 as a tumor target or marker candidate for breast cancer therapy.