The molecular basis of IGF-II/IGF2R recognition: a combined molecular dynamics simulation, free-energy calculation and computational alanine scanning study

Insulin-like growth factor-II (IGF-II) is a key regulator of cell growth, survival, migration and differentiation, and is thus pivotal in many cancers. An individual with a high IGF-II level is at high risk of developing cancer, whereas IGF2R is implicated as being important in tumor suppression. Thus, uncovering the essence of the IGF-II/IGF2R interaction is very important to understanding the origin of the tumor-suppressing effect of IGF2R. In this study, in order to investigate the interaction of the IGF-II/IGF2R complex and to characterize the binding hot spots of this interaction, a 10 ns molecular dynamics simulation combined with MM-PBSA/MM-GBSA computations and computational alanine scanning was performed on the IGF-II/IGF2R complex. From the results of the free-energy decomposition and the computational alanine scanning calculation, we identified the key residues in the IGF-II/IGF-2R interaction. The results from the calculation were consistent with reported experimental mutagenesis studies. The information on the interaction of IGF-II and IGF2R obtained is vital for understanding how the structure of IGF2R influences the function of IGF-II in growth and development. This study will also lead to new opportunities to develop molecular probes that can assist in diagnostic screening, and even novel approaches to controlling tumor development.