BACKGROUNDTo study the anti-invasive effects and its mechanism and apoptosis induction of pentacyclic triterpenoid including glycyrrhizin (GL), 18β-glycyrrhetinic acid (GA), ursolic acid (UA) and oleanolic acid (OA) in highly potentially metastatic lung cancer cell line (PGCL3).

METHODSThe invasive ability, the adhesive ability, the migration ability and the activity of cathepsin B (CB) of PGCL3 cells treated with the four drugs were determined by the invasion test of reconstituted basement membrane, the laminin adhesion test, the chemotactic migration test and the enzymological method of CB. The apoptosis of the cells was detected with acridine orange-ethidium bromide fluorescent stain (AO/EB) and TUNEL.

RESULTSThe GL,GA, UA and OA could decrease the proliferative ability of PGCL3 cells, and their IC₅₀ values were 1.83 mmol/L, 145.3 μmol/L, 44.73 μmol/L and 40.71 μmol/L respectively. After treatment with 0.5 and 1.0 mmol/L GL, 25 and 50 μmol/L GA, 30 and 40 μmol/L UA, 35 and 45 μmol/L OA for 96 h, the invasive ability of the PGCL3 cells was significantly decreased compared with that of the control groups ( P < 0.01 or P < 0.001). The adhesive and migration ability, the secretion of CB and the colony-formation number in semi solid agar were significantly decreased after PGCL3 cells were treated with the above concentration of the four drugs for 96 h ( P < 0.05, P < 0.01 or P < 0.001), and the inhibition was in a dose-dependent fashion. The percentages of apoptosis of the cells were obviously increased after treatment with the above concentration of the four durgs for 48 h, compared with the control group ( P < 0.05 or P < 0.01).

CONCLUSIONSAll of the four drugs can inhibit the proliferative and invasive ability, and induce apoptosis of the PGCL3 human lung cancer cells. The mechanism of anti invasion may be to inhibit the adhesion, migration, and the CB secretion of the cells.