■雷帕霉素抑制mTOR蛋白激酶。蛋氨酸酶(rMETase),通过降解蛋氨酸,针对癌细胞的蛋氨酸成瘾,并已被证明可以提高化疗药物的疗效,减少有效剂量。我们以前的研究表明,雷帕霉素和rMETase协同作用对抗结直肠癌细胞,但不是在正常细胞上,当在体外同时给药时。在本研究中,我们旨在通过探索雷帕霉素和rMETase在依次用于HCT-116结直肠癌细胞时是否存在协同作用来进一步我们之前的发现,与同时给药相比,在体外。
单独的雷帕霉素和单独的rMETase对HCT-116人结直肠癌细胞系的半数最大抑制浓度(IC50)先前使用CCK-8细胞活力测定来测定(11)。然后我们检查了雷帕霉素和rMETase的疗效,在HCT-116细胞系上同时或依次施用,雷帕霉素在rMETase之前给药,反之亦然。
■雷帕霉素和rMETase的IC50,从以前的实验中确定(11),为1.38nM和0.39U/ml,分别,HCT-116细胞。当rMETase在雷帕霉素前四天给药时,在IC50下,HCT-116细胞均有30.46%的抑制.当rMETase前四天服用雷帕霉素时,在IC50下,均有41.13%的抑制作用。当雷帕霉素和rMETase同时给药时,在IC50下,均有71.03%的抑制作用。
■雷帕霉素和rMETase在体外同时给药时对大肠癌细胞具有协同作用,但不是顺序。
UNASSIGNED: Rapamycin inhibits the mTOR protein kinase. Methioninase (rMETase), by degrading methionine, targets the methionine addiction of cancer cells and has been shown to improve the efficacy of chemotherapy drugs, reducing their effective doses. Our previous study demonstrated that rapamycin and rMETase work synergistically against colorectal-cancer cells, but not on normal cells, when administered simultaneously in vitro. In the present study, we aimed to further our previous findings by exploring whether synergy exists between rapamycin and rMETase when used sequentially against HCT-116 colorectal-carcinoma cells, compared to simultaneous administration, in vitro.
UNASSIGNED: The half-maximal inhibitory concentrations (IC50) of rapamycin alone and rMETase alone against the HCT-116 human colorectal-cancer cell line were previously determined using the CCK-8 cell viability assay (11). We then examined the efficacy of rapamycin and rMETase, both at their IC50, administered simultaneously or sequentially on the HCT-116 cell line, with rapamycin administered before rMETase and vice versa.
UNASSIGNED: The IC50 for rapamycin and rMETase, determined from previous experiments (11), was 1.38 nM and 0.39 U/ml, respectively, of HCT-116 cells. When rMETase was administered four days before rapamycin, both at the IC50, there was a 30.46% inhibition of HCT-116 cells. When rapamycin was administered four days before rMETase, both at the IC50, there was an inhibition of 41.13%. When both rapamycin and rMETase were simultaneously administered, both at the IC50, there was a 71.03% inhibition.
UNASSIGNED: Rapamycin and rMETase have synergistic efficacy against colorectal-cancer cells in vitro when administered simultaneously, but not sequentially.