OBJECTIVETo investigate the effect of metformin on 3T3-L1 preadipocyte's differentiation and consequently observe the anti-proliferative effects of metformin-treated adipocytes on leukemia cells.

METHODSDifferent concentrations of metformin were added in 3T3-L1 preadipocytes to induce maturation, the matured adipocytes were detected by oil red O staining and quantified by absorbance value (OD). Real-time PCR was used to detect the mRNA expression level of the key adipogenic genes PPARγ, C/EBPα and FABP4(ap2). The adipocytes were co-cultured with GFP+-THP-1 cells, 1 µg/ml of cytarabine(Ara-C) was added and incubated for 48 hours, the flow cytometry was used to detect the apoptosis rate of GFP+-THP-1 cells. Adipocyte supernatant was collected and mixed with equal volume of tumor lysat medium (RPMI 1640) at 1:1 to culture tumor cells. The leukemia cell proliferation activity was detected by CCK-8; after 48 hours of adding 1 µg/ml Ara-C, the protective effect on chemotherapy was assayed by using cytometer.

RESULTSThe metformin lowered the OD value, and the expression levels of both adipogenic genes C/EBPα and FABP4 were lower than those of controls, while the expression level of PPARγ mRNA was not significantly changed, the apoptosis rate of leukemia cells co-caltured with metformin-treated adipocytes was higher than that of co-cultured cells without metformin treatment. The adipocytes promoted the leukimia cell proliferation and protected leukemia cells from chemotherapy, which could be abrogated by metformin.

CONCLUSIONThe metformin can inhibit the differentiation of 3T3-L1 preadipocytes into adipocytes, and can regulate the protective effect of adipocytes on the apoptosis, proliferation and chemotherapy of leukemia cells.