Objective:To evaluate the role of spinal mammlian target of rapamycin (mTOR)/ribosomal S6 kinase 1 (S6K1)/glioma associated oncogene homolog 1 (Gli1) signaling pathway in chronic morphine tolerance in mice.Methods:Healthy male Kunming mice, aged 8-10 weeks, weighing 23-25 g, were used in the study.The experiment was performed in two parts.Experiment I Fifty mice were randomly assigned into 2 groups: normal saline group (group S, n=10) and morphine group (group M, n=40). In M and S groups, morphine and normal saline 10 mg/kg were injected subcutaneously, respectively, twice a day for 7 consecutive days.The thermal pain threshold (TPT) was measured and the maximum analgesic effect percentage (MPE) was calculated at 1 day before administration and 30 min after the last administration every day.Ten mice in each group were randomly selected and sacrificed after measurement of TPT at 1, 3, 5 and 7 days after administration in group M and after the last measurement of TPT in group S, and the lumbar segment (L 4-6) of the spinal cord was removed.Experiment Ⅱ Forty mice were randomly divided into 4 groups ( n=10 each): KU-0063794+ morphine group (group KU+ M), dimethyl sulfoxide (DMSO)+ morphine group (group DM+ M), morphine+ KU-0063794 group (group M+ KU) and morphine + DMSO group (group M+ DM). Morphine 10 mg/kg was injected subcutaneously twice a day for 7 consecutive days in 4 groups.At 1-3 days of morphine injection, mTOR specific inhibitor KU-0063794 200μl (1 μg/μl) and 10% DMSO 200 μl was injected intraperitoneally in KU+ M group and DM+ M group at 30 min before administration twice a day.At 5-7 days of morphine injection, KU-0063794 200μl (1 μg/μl) or 10% DMSO 200 μl was injected intraperitoneally in group M+ KU or group M+ DM at 30min before administration, respectively, twice a day.TPT was measured and MPE was calculated at 1 day before morphine injection and at 30 min after the last administration every day.The animals were sacrificed after the last measurement of TPT, and the lumbar segment (L 4-6) of the spinal cord was removed for determination of the expression of spinal mTOR, phosphorylated mTOR (p-mTOR), S6K1, phosphorylated S6K1 (p-S6K1) and Gli1 (using Western blot). Results:Experiment Ⅰ Compared with group S, MPE was significantly increased at each time point after administration at 3, 5 and 7 days after administration, expression of spinal p-mTOR, p-S6K1 and Gli1 was significantly down-regulated ( P<0.05), and no significant change was found in mTOR and S6K1 in group M ( P>0.05). Experiment Ⅱ Compared with group DM+ M, MPE was significantly decreased at 3-7 days after morphine injection, expression of p-mTOR, p-S6K1 and Gli1 in spinal cord was down-regulated ( P<0.05), and no significant change was found in expression of mTOR and S6K1 in group KU+ M ( P>0.05). Compared with group M+ DM, MPE was significantly increased at 6-7 days after morphine injection, expression of p-mTOR, p-S6K1 and Gli1 in spinal cord was down-regulated ( P<0.05), and no significant change was found in mTOR and S6K1 in group M+ KU ( P>0.05). Conclution:Spinal mTOR/S6K1/Gli1 signaling pathway is involved in the development and maintenance of chronic morphine tolerance in mice.

Objective To investigate the effects of different culture conditions(RPMI-1640,DMEM and DMEM/F12 medium)on the passage of MPM cells isolated from the tissues of Malignant pleural mesothelioma(MPM),and to study the effects of CDKN2B on the proliferation,invasion and apoptosis of MPM cells.Methods MPM cells were isolated from MPM tissues and cultured in RPMI-1640,DMEM and DMEM/F12 medium,respectively.Cell proliferation was examined by CCK-8,and the nuclei and chromosomes were observed by Wright-Giemsa staining.Fluorescence intensities of Calretinin,CD141,CK5,EMA and WT-1 were conducted by immunofluorescence assay.The mRNA and protein expression of CDKN2B were detected by RT-qPCR and Western blot,respectively.Transwell was used to detect cell invasion and flow cytometry was used to detect cell apoptosis.Results The established MPM cells showed good viability when passaged to the 10th generation in RPMI-1640,DMEM and DMEM/F12 cultures,and the MPM markers Calretinin,CD141,CK5,EMA and WT-1 were all expressed in the cells.The viability of MPM cells in RPMI-1640 culture medium was relatively stable.CDKN2B was downregulated in MPM cells(P<0.05),and overexpression of CDKN2B significantly suppressed the proliferation(P<0.05),invasion(P<0.05)and epithelial interstitial transformation of MPM cells(P<0.01),and promoted the apoptosis(P<0.01).Conclusion The established MPM cells were stably passaged in RPMI-1640 culture medium,and CDKN2B may be a potential target for the diagnosis and treatment of MPM.