Synergistically Antiproliferative Effect Of Melatonin And Cisplatin On Human Esophageal Cancer Cell Lines And The Possible Mechanism

Objective: The purpose of this paper is to explore the effects of melatonin combinedcisplatin on the proliferation and apoptosis of human esopHageal cancer cells Eca109,and to study the possible mechanism of apoptosis, which can develop a new effectivetherapy for esopHageal cancer.Methods:①Human esopHageal cancer cells Eca109were co-cultured with differentconcentrations of melatonin(10^-910^-5mol mol L^-1) with or without cisplatin(2.5mgmol L^-1) for24h. The inhibitory rate of human esopHageal cancer cells Eca109weremeasured by the3-（4,5-dimethylthiazol-2-yl）-2,5-dipHenyl-tetrazolium bromide （MTT）assay;②Five doses of melatonin(10^-9,10^-8,10^-7,10^-6,10^-5mol L^-1) were used tocombine with cisplatin(2.5mg L^-1). The coefficient of drug interaction was used toanalyse the synergistically inhibitory effect of drug combination.③The antiproliferativeeffect of melatonin combined cisplatin on Eca^-109was measured by colony formationassay;④The cell apoptosis was analyzed using flow cytometry with propidium iodidestaining.⑤AcridineWestern Blot for apoptosis-related protein Bcl-2and Bax wereused to analyse possible mechanisms of the synergistic antiproliferation effect ofmelatonin in combination with cisplatin.Results:①W hen Eca109cells were co-cultured with different concentrations ofmelatonin and cisplatin(2.5mg L^-1), the inhibitory rates were significantly higher thanthose inhitory rates of single cisplatin or melatonin administration at the same dose. ②Melatonin combining with cisplatin showed synergistically inhibitory effect on theproliferation of the two cell lines in appropriate concentrations.③D ifferentoncentration-s of melatonin combined with cisplatin at2.5mg L^-1showed an obviouslyenhanced inhibitory effect on colony formation of Eca109cells.④Melatonin(10^-5mol L^-1) of Eca109cells for24h induced an apoptosis rate of only7.8%, but whencombined with2.5mg L^-1cisplatin, the cell apoptosis rate increased to32%,significantly higher than that in cells with cisplatin treatment alone （9.7%）.⑤Comparedwith the control group，Western Blot’s test shows that, Mel and DDP alone or incombination with Eca109’s Bcl-2protein expression decreased, with pale, enhanced theexpression of Bax protein, with deepening. the performance of the group with two drugscombined is the most obvious, we can conclude that Mel assist melatonin enhanced thepossible mechanism of cisplatin efficacy and the downregulation of Bcl-2andupregulation of Bax protein expression.Conclusions: Melatonin can enhance theanti-proliferative effect of cisplatin on Eca109cell and can enhance cisplatin-inducedcell’s death. This experimental research provides a certain foundation for the clinicaltreatment of esopHageal cancer.