The experimental study of cell density mediated integrin αγβ6 expression and MMP-9 secretion in colon cancer cells / 中华普通外科杂志

ABSTRACT

Objective To detect the effect of cell density off both integrin αγβ6 expression and matrix metalloproteinase-9(MMP-9)secretion in colon cancer cells. Methods Flow cytometry was applied to analyze αγβ6 expression in human WiDr colon cancer cell lines and human HaCaT keratinocyte cells, respectively,at high-and low-cell density culture.The MMP-9 aetivity level for various coloIl cancer cell lines, WiDr and SW480 cells at high-and low-cell density culture was analyzed using Biotrak MMP-9 activity assay and Gelatin Zymography assay, respectively. Results High cell density significantly enhances integrin αγβ6 expression for WiDr cells expressing αγβ6 compared with low density,but no increase was observed for human keratinocyte HaCaT cells. Biotrak MMP-9 assay indicated that the amount of MMP-9 secreted per cell for WiDr and SW480 B6 cells at high cell density culture was(3.3±1.2)×10-7ng/cell and(27.2±3.0)× 10-7ng/cell respectively; However,at low cell density it was(1.8±0.7)× 10-7ng/cell and(10.9±2.0)×10-7 ng/cell,respectively. It was 2-3-fold higher for WiDr and SW480 β6 cells at high cell density compared with that at low cell density, but no density-dependent increase observed for SW480 wild cells lack αγβ6 expression(t=0.47,P＞0.05),MMP-9 secretion for SW480 wild cells was(3.9±1.7)× 10-7 ng/cell at hish cell density and(3.8 ±0.7)×10-7 ng/cell at low eell density(P＞0.05),respectively. Gelatin zymography assay also indicated that the level of MMP-9 in SW480 B6 cells expressing αγβ6 was evidently higher at high density than at low density, however no density-dependent increase observed for SW480 wild cells and HaCaT cells. Conclusions High cell density induces integrin αγβ6 expression and promotes MMP-9 secretion in colon cancer cells, which constitutes the basis for a self-perpetuating system of tumor infiltrating growth in colon cancer progression.