OBJECTIVETo investigate whether there is intercellular transfer of functional P-glycoprotein(P-gp) from P-gp-positive cells to P-gp-negative cells in vitro.

METHODSHepG2/GFP cells, a HepG2 cell line stably expressing GFP, were co-cultured with HepG2/ADM cells, an adriamycin-resistant cell line derived from HepG2 cells. The distribution of P-gp in hepatocellular carcinoma cell was observed under laser scanning confocal microscope (LSCM). Immunomagnetic beads were used to separate HepG2/GFP cells from the mixed culture. The abundance of P-gp was analyzed by western blot, and the expression of mdr1 mRNA was detected by qRT-PCR.

RESULTSYellow fluorescence was detected in HepG2/aqMDR cells, green fluorescence was detected in HepG2/GFP cells, red fluorescence was detected in HepG2/ADM cells by LSCM. The level of P-gp protein in HepG2/aqMDR cells was lower than that in HepG2/ADM cells, but higher than that in HepG2/GFP cells (q = 35.07, P < 0.05) and HepG2 cells (q = 36.87, P < 0.05). The expression of mdr1 mRNA in HepG2/ADM cells was higher than that in HepG2/aqMDR, HepG2 and HepG2/GFP cells, but there was no significant difference in mdr1 mRNA among HepG2/aqMDR, HepG2 and HepG2/GFP cells (F = 2.30, P > 0.05).

CONCLUSIONSP-gp can transfer from drug resistant hepatocellular cells to sensitive hepatocellular carcinoma cells. This study suggests a novel mechanism of multidrug resistance in hepatocellular carcinoma.