Abstract
[Background] Recent studies have suggested that ionizing radiation enhances metastasis and invasion of tumor cells. Although some factors such as MMP, which degrades extracellular matrix, and RhoA, which regulates cellular cytoskeleton, are thought to be involved in this phenomenon, its precise mechanism has not been clearly shown. Assuming that radiation-induced bystander effect influences on cellular invasive ability, we here studied whether irradiated cell condition media (ICCM) enhanced invasive ability of non-irradiated cells.
[Methods] Human lung cancer-derived A549 cells were irradiated with 2 or 4 Gy (2.55 Gy/min) of X-rays, and the media (ICCM) were collected for the experiments. In order to evaluate cellular invasive ability, ICCM containing 1% FBS were added to the lower chamber of Matrigel Invasion Chamber (BD) and non-irradiated cells suspended in fresh media were loaded into the upper chamber, and the number of invaded cells was counted. The effect of ICCM on ERK phosphorylation was examined by Western blotting.
[Results] ICCM enhanced cellular invasive ability in a dose-dependent manner, and induced ERK phosphorylation. These results suggested that ICCM enhanced cellular invasive ability via ERK.
