Fitness Differences Between Cisplatin-Resistant And Cisplatin-Sensitive Cells Indicate A Strategy To Delay The Development Of Cisplatin Resistance

Objective:To explore fitness differenees between cisplatin-resistant cells and cisplatin-sensitive cells and its potential mechanism.To confirm if cisplatin-resistant cells growth could be suppressed by cisplatin-sensitive cells during cisplatin treatment in vivo.To compare the outcome of different therapeutic schedules by mathematical model based on tumor growth parameters in vivo.Method:HeLa/ddp,HGC27/ddp,and AGS/ddp cell lines were developed by the continuous exposure of the parental cells to various concentrations of ddp.The consumption of glutamine was determined by cell growth curve.The antioxidant capacity was determined by cell viability assay,eolony-formation assay and flow cytometry.The expression of KRAS、GLS、GOTI.GLUD1 were determined by qRT-PCR and Western Blotting.The growth ability of sensitive cells and resistant cells were determined both in vitro and in vivo.Tumor xenograft model which contains HeLa and HeLa/ddp cells was established to further evaluate if ddp-sensitive cells could suppress the growth of ddp-resistant cells during cisplatin treatment.The survival benefits of different therapeutic schedules were determined by mathematical modelling which was based on tumor growth parameters in vivo.Results:Ddp-resistant cells showed significantly increased glutamine consumption.Antioxidant capacity was apparently enhanced in ddp-resistant cells and directly related to the presence of glutamine.The KRAS-mediated signaling pathway,which contributed to the maintenance of cellular redox homeostasis by consuming glutamine,was enhanced in resistant cells by increasing GOT1 expression and decreasing GLUD1 expression.Rapid glutamine catabolism was unnecessary for ddp-resistant cells growth in the absence of drug but indispensable for the maintenance of drug resistance.Growth of ddp-resistant cells was signifieantly slower than that of sensitive cells in vitro and further study indicated ddp-resistant cells had a lower proliferation and a higher apoptosis rate.Besides,resistant tumors growth was remarkably slower than sensitive tumors in vivo.Further study indicated that resistant tumor cells proliferated more slowly than sensitive tumor cells and 6%of the cells in resistant tumor,compared with 1.5%in sensitive tumor,were apoptotic.Resistant cells growth was completely inhibited by sensitive cells when they coexist in mice.Ddp-resistant cells development was signifieantly suppressed by maintaining a certain amount of ddp-sensitive cells during treatment in vivo.Our mathematical modelling indicated that a signifieant survival benefit might be achieved through appropriate treatment intervals.By switching between the two dosing frequencies,such adaptive therapy strategy could achieve not only a long survival time but also a relatively small tumor burden.Conclusion:Ddp-resistant cells are less fit than sensitive cells due to enhanced antioxidant capacity and their growth can be suppressed by sensitive cells in vivo.To control or slow tumor growth by exploiting intratumoral competition between ddp-sensitive and ddp-resistant clones is a better strategy than to eradicate the tumor.