Involvement Of Spinal Calcium/calmodulin-dependent Protein Kinase?-dependent KIF17/NR2B Trafficking In The Development Of Bone Cancer Pain

Objective To investigate the involvement of Calcium/Calmodulin-dependent protein kinase ?(CaMK?)-dependent KIF17/NR2B trafficking in the development of bone cancer pain.Methods Eighty-eight male C3H/HeJ mice were randomly divided into 5 groups:sham group(S,n=20),tumor-bearing group(T,n=26)and KN93 group(K1,K2,K3,n=42).The mouse model of bone cancer pain was established by intra-femur inoculations of osteolytic NCTC 2472 cells in T and K groups.At 14d post operation,mice in Group K or T,S received intrathecal injection of 15nmol,30nmol,60nmol KN93 dissolved in 20%DMSO(5 ?l)or vehicle respectively.Eight mice were selected randomly from each group at Od before inoculations and 3,5,7,10,14d after inoculations as well as 1,2,4,24h after administration for measurement of spontaneous flinches and paw withdrawal mechanical threshold(PWMT)to von Frey filaments stimulation.Another 3 mice were sacrificed at the corresponding time points and the spinal cord was obtained for expression of pCaMKII,NR2B,KIF17 determined by western blot.Results(1)A11 mice displayed some pain behaviors at 3d after inoculation,but there was no significant difference between tumor-bearing and sham mice.At 5d,the pain behaviors of all mice recovered to the baseline.At 7d,the number of spontaneous flinches in tumor-bearing group gradually increased and PWMT decreased over time until 14d compared with sham group(P<0.05).Similarly,spinal p-CaMK?,NR2B,KIF17 expression was dramatically elevated from day 7 to 14 compared with baseline and S group(P<0.05).(2)Treatment with KN93 30nmol and 60nmol rather than 15nmol could attenuate pain behaviors effectively and suppressed the expression of p-CaMK ?,NR2B,KIF 17 in a dose-dependent manner.Additionally one hour later,the number of spontaneous flinches in K2 and K3 groups started to decrease while PWMT increased(P<0.05),and the effect lasted for more than 4 hours.Consistent with behavioral results,the effect of 60nmol KN93 on NR2B,pCaMKII and KIF17 expression started at 1h,achieved maximum at 2h,attenuated at 4h(P<0.05)and vanished at 24h(P>0.05)in contrast to the baseline.Conclusion CaMKII-dependent regulation of KIF17/NR2B trafficking may participate in the development of bone cancer pain.Intrathecal administration of KN93 could ameliorate bone cancer pain and down-regulates the expression of p-CaMK?,NR2B,KIF17 proteins in a dose-dependent and time-relative manner.