Inhibition of invasion and MMPs by a nutrient mixture in human cancer cell lines: a correlation study
Matrix metalloproteinase (MMP)-2 and -9 secretion is elevated in various human cancers and their elevated expression has been associated with poor prognosis due to associated increased cancer cell invasion and metastasis. Aim: To examine the correlation between in vitro MMP-2 and MMP-9 secretion and Matrigel invasion in 42 different human cancer cell lines (selected on the basis of organ malignancies) treated with a nutrient mixture (NM). 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. Results: 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. Conclusions: 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.
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