Materials and Methods:
The cells were cultured in their recommended media supplemented with 10% FBS and antibiotics in 24-well tissue culture plates. At near confluence, the cells were treated with NM dissolved in media at 0, 10, 50, 100, 500 and 1000 μg/mL in triplicate. Parallel sets of cultures were also treated with phorbol 12-myristate 13-acetate (PMA) 100 ng/mL for induction of enzymes. After 24 h the media were collected and MMP-2 and MMP-9 levels were assayed by gelatinase zymography. Invasion studies were conducted using Matrigel in 24-well plates.
Correlation of pooled data from different cancer cell line groups demonstrated dose-dependent inhibition of MMP-2 and -9 and Matrigel invasion with NM treatment and significant negative correlation between MMP-2 and MMP-9 levels and Matrigel invasion. Pooled data of cell lines expressing only MMP-2 and resistance to PMA induction of MMP-9 showed significant negative correlation (r=-0.77, p=0.003) between MMP-2 secretion and inhibition of invasion through Matrigel. Cell lines expressing only MMP-9, showed significant negative correlation (r= -0.726, p=0.003) between MMP-9 secretion and Matrigel invasion. Pooled data of cell lines expressing MMP-2 and MMP-9 demonstrated significant negative correlation ( r = -0.821. p < 0.0001) between MMP-9 secretion and inhibition of invasion through Matrigel, Pooled data of cancer cell lines expressing no basal MMP-9 secretion demonstrated significant negative correlation ( r = -0.686, p < 0.0001) between PMA-induced MMP-9 secretion and inhibition of invasion through Matrigel.
In conclusion, regardless of MMP-2 and MMP-9 patterns of expression, MMP modulation by NM was found to be significantly correlated with NM modulation of Matrigel invasion of these cell lines.
Human cancer cells, nutrient mixture, correlation of invasion with MMPs