Radiation induced MMP expression from rectal cancer is short lived but contributes to in vitro invasion

Aims Matrix metalloproteinase (MMP) activity is increased after radiation. The aims of this study were to assess the time course of this increase and its effects on malignant cell invasion. Methods Colorectal cancer (HCT116, LoVo, C170HM2, CaCO-2), fibroblast (46-BR.IGI, CCD-18Co) and fibrosarcoma (HT1080) cell lines were irradiated at 4 gray (4 Gy) and matrix metalloproteinase gene and protein expression examined over a 96 h period by real time polymerase chain reaction and gelatin zymography. Invasion was assessed on Matrigel. Human rectal tumour MMP expression was compared before and after long course radiotherapy. Results Radiation increased MMP gene expression of tumour cell lines, and resulted in increased MMP protein activity in the HT1080 line. HT1080 and HCT116 in monoculture and LoVo in co-culture were more invasive after radiation at 48 h in vitro, but long course radiotherapy did not result in a consistent increase in MMP expression from human rectal tumour biopsies. Conclusions Radiation results in increased MMP expression for a limited time period. This results in an early increase in cell line invasion. Further clinical research is required to clarify if MMP inhibition given perioperatively following radiotherapy decreases local recurrence rates.