LILRA3 attenuates U937 cell migration by decreasing expression
of certain chemokines
A transwell test was applied to investigate cell migration. We found
that after 6 hours of incubation in 10% FBS containing RPMI-1640, few
of the U937 cells overexpressing LILRA3 had migrated into the lower
chamber compared with cells harboring the null vector (p <
0.001) (Figure 3F). Chemokines and their seven-transmembrane, G-protein
coupled receptors are recognized as key mediators physiologically
directing cell migration. We then performed Elisa assay to detect
expression of two CC-type chemokines (CCL2, CCL3) and other two CXC-type
chemokines (CXCL8/IL-8, CXCL10), which were predominantly expressed in
monocytes. Interestingly, we found that CCL2, CCL3, IL-8, CXCL10 were
significantly suppressed by LILRA3 (p < 0.001) (Figure 3G). To
verify our findings, we then added a certain amount of recombinant CCL2
or CXCL8 (Peprotech, Rocky Hill, USA) to the upper chamber, and the
migration assay results showed that the migration capacity, inhibited by
LILRA3, was reversed by the exogenous IL-8 (p<0.01) (Figure
3H). The data suggest that LILRA3 attenuates the migration capacity of
U937 cell lines mainly by suppressing IL-8 secretion.