Anti-cancer Effects Of Rapamycin On Hematological Malignant Cell Lines

【Objective】(1)To investigate anti-proliferation effects of rapamycin(RAP) alone or in combination with arsenic trioxide (As2O3) on some human hematological malignancies cell line. (2)To investigate the mechanism of rapamycin,s anti-cancer effects through U937 cell line.【Methods】(1)Cell viability and proliferation were analyzed by MTT and cell counting after cultured in rapamycin; (2)Clone formulating ability was analyzed by 1% methylcellulose semisolid culture medium, cell colony was observed through inverted microscope; (3)The change of cell cycle was analyzed by propidium iodide staining; (4)The phosphorylation level of mammalian target of rapamycin (mTOR) was detected by flow cytometric; (4)Expression of p27 protein was detected by western blot semiquantitative method.【Results】(1)Human acute leukemic monocyte cell line U937,THP-1, acute T lymphoblastic leukemia cell line A3, multiple myeloma cell lines RPMI8226 were sensitive to rapamycin, the proliferation inhibition rate range 20% to 50%. Meanwhile, The proliferation of K562,SHI-2 cell lines were not influenced. With increasing concentrations of rapamycin 10, 100, 1000nmol/L, U937 cell proliferation inhibition rates were (16.6±1.5)%, (29.8±3.0)%, (49.1±2.0)%, respectively, (p<0.01), after culture 72 hours. An addition of arsenic trioxide enhanced the inhibitory effects of rapamycin, indicating that the combination of these agents was more potent in inhibiting the growth of the cell line than each agent alone. (2)Clonogenic assay showed rapamycin 10nmol/L, the inhibit rates was (57.06±3.69)%, the cluster/colony relative values of control group and apamycin 10nmol/L were 0.28±0.05, 1.04±0.27, respectively , (p<0.01); (3)Propidium iodide (PI) measurement showed rapamycin 0, 10, 100, 1000mol/L, cell G1 phase percentages were (44.30±0.92)%, (46.63±1.25)%, (53.57±2.82)%, (62.70±6.77)%, respectively; cell S phase percentages were (44.93±2.41)%, (44.53±1.51)%, (36.33±6.02)%, (27.00±7.54)%, respectively, (p<0.01); (4)When treated with rapamycin 0, 10nmol/L, Fluorescence strengths of p-mTOR were 3.53±0.27, 2.37±0.07, respectively, (p<0.01); (5)The expression of p27 enhanced when treated with rapamycin (10nmol/L), the gray scale relative value was 6.77.【Conclusions】Rapamycin can target to mTOR kinase, cause cell cycle blocking in G1 phase, can inhibit the proliferation and clone forming ability of hematological malignant cell lines. Rapamycin has the anti-cancer effects.