RESUMO
Exosomes are nanosized small membrane microvesicles of endocytic origin secreted by most cell types. Exosomes, through its carrying protein or RNA from derived cells, affect gene regulation networks or epigenetic reorganization of receptor cell, and then modulate the physiological processes of cells. Studies have shown that external exosomes secreted by breast cancer cells or other cells play an important role in the development of tumor, including cell migration, cell differentiation and the immune response, etc. In this article, the latest studies were summarized to provide an overview of current understanding of exosomes in breast cancer.
Assuntos
Neoplasias da Mama , Exossomos , Movimento Celular , Humanos , RNARESUMO
To understand the molecular etiology of osteosarcoma, we isolated and characterized a human osteosarcoma cell line (OS1). OS1 cells have high osteogenic potential in differentiation induction media. Molecular analysis reveals OS1 cells express the pocket protein pRB and the runt-related transcription factor Runx2. Strikingly, Runx2 is expressed at higher levels in OS1 cells than in human fetal osteoblasts. Both pRB and Runx2 have growth suppressive potential in osteoblasts and are key factors controlling competency for osteoblast differentiation. The high levels of Runx2 clearly suggest osteosarcomas may form from committed osteoblasts that have bypassed growth restrictions normally imposed by Runx2. Interestingly, OS1 cells do not exhibit p53 expression and thus lack a functional p53/p21 DNA damage response pathway as has been observed for other osteosarcoma cell types. Absence of this pathway predicts genomic instability and/or vulnerability to secondary mutations that may counteract the anti-proliferative activity of Runx2 that is normally observed in osteoblasts. We conclude OS1 cells provide a valuable cell culture model to examine molecular events that are responsible for the pathologic conversion of phenotypically normal osteoblast precursors into osteosarcoma cells.
