J Cancer 2019; 10(26):6481-6490. doi:10.7150/jca.33223
LOX inhibition downregulates MMP-2 and MMP-9 in gastric cancer tissues and cells
1. Department of Pathogenic Biology and Immunology, School of Basic Medical Sciences, Ningxia Medical University;
2. Department of Rheumatology and Immunology, The General Hospital of Ningxia Medical University, Yinchuan, Ningxia 750004, P.R. China;
*These authors contributed equally to this work
Zhao L, Niu H, Liu Y, Wang L, Zhang N, Zhang G, Liu R, Han M. LOX inhibition downregulates MMP-2 and MMP-9 in gastric cancer tissues and cells. J Cancer 2019; 10(26):6481-6490. doi:10.7150/jca.33223. Available from http://www.jcancer.org/v10p6481.htm
Objective: The objective of this study was to analyze the effects of lysyl oxidase (LOX) on the expression and enzyme activity of the matrix metalloproteinases 2 (MMP-2) and 9 (MMP-9) and to study its preliminary effect mechanisms.
Methods: We collected fresh cancer specimens from 49 gastric cancer patients who underwent surgery. Immunohistochemistry was used to quantitate the protein expression levels of LOX and MMP-9 in gastric cancer tissues and to analyze their correlation. Also, six-week old nude mice were divided into a control group and a LOX inhibition group. SGC-7901 gastric cancer cells were inoculated subcutaneously into the backs of the two groups of these mice to construct a gastric cancer-bearing nude mouse model. In the LOX inhibition group, β-aminopropionitrile (BAPN) was used to inhibit LOX. Western blotting was used to quantitate the relative expression levels of MMP-2 and MMP-9 in mouse tumor tissues, and gelatin zymography was used to quantitate their enzyme activity levels. In addition, BGC-823 gastric cancer cells were cultured, then 0.1 mM, 0.2 mM, and 0.3 mM BAPN and 2.5 nM, 5 nM, and 10 nM LOX were added to treat BGC-823 cells. ELISA and gelatin zymography were used to quantitate the protein concentrations and changes in enzyme activity of MMP-2 and MMP-9 in the culture supernatant. Western blotting was used to quantitate the relative expression levels of platelet derived growth factor receptor (PDGFR) in the BGC-823 gastric cancer cells after LOX inhibition and exogenous LOX addition.
Results: In the tissues from the gastric cancer patients, the relative expression levels of LOX and MMP-9 were positively correlated (r = 0.326, P < 0.05). Compared with the control group, the tumor tissues from mice in the LOX inhibition group had reduced relative expression levels and enzyme activities of MMP-2 and MMP-9 (P < 0.05). After LOX were inhibited with different concentrations of BAPN in BGC-823 gastric cancer cells, the protein concentrations and enzyme activity levels of MMP-2 and MMP-9 in the culture supernatants were decreased (P < 0.05). In addition, the relative expression level of PDGFR in gastric cancer was decreased when BAPN concentrations increased, showing a negative dose-dependent manner (rPDGFR-α = -0.964, rPDGFR-β = -0.988, P < 0.05). After exogenous LOX treating BGC-823 cells, the concentrations and enzyme activity levels of MMP-2 and MMP-9 in the cell supernatant were increased (P < 0.05). Further, the relative expression of PDGFR in gastric cancer cells was increased with the increase of exogenous LOX, showing a positive dose-dependent manner (rPDGFR-α=0.952, rPDGFR-β=0.953, P<0.05).
Conclusions: LOX inhibition can inhibit the expression and enzyme activity of MMP-2 and MMP-9 in gastric cancer tissues and cells, and the probable mechanism is through its effects on the PDGF-PDGFR signaling pathway.
Keywords: lysyl oxidase, matrix metalloproteinase-2, matrix metalloproteinase-9, β-aminopropionitrile, gastric cancer, PDGF-PDGFR