Effects of Imatinib and Rapamycin on the mTOR/S6 Signal Transduction Pathway in CD33+ Cell of CML
Authors: He Guangsheng , Xie Jing , Depei Wu , Zhang Xiang , Sun Aining 
Published: April 2020

Abstract
Objective: To evaluate the changes of the mTOR/S6 signal transduction pathway of CD33+ cell in chronic myeloid leukemia (CML), and the effect of imatinib and rapamycin on it. Since the RAPA could influenced the immunity of T cell, the changes of expression of IFN-γ in CD3+, CD3+CD8− and CD3+CD8+T cell was evaluated after treating with RAPA.
Methods: By flow cytometry, the contents of p-mTOR and p-S6 in CD33+ cells were detected in the new diagnosed CML, CML treated with imatinib or hydroxycarbamide and interferon (HU+IFN), CML resisted imatinib, and normal control, or after treated with RAPA in vitro, respectively. Then expression of IFN-γ in CD3+, CD3+CD8− and CD3+CD8+T cell in patients with higher levels of p-mTOR/p-S6 was measured after RAPA.
Results:
The contents of p-mTOR and p-S6 in CD33+ cell in the primary CML were higher than that in the normal control m(9.53±7.87)%vs(2.43±2.54)% GP&lt;0.05] [(7.64±3.17)%vs(1.21±1.44)%; P&lt;0.05], could be reduced by RAPA in vitro [(9.53±7. 87)%vs(3.64±3.29)%, p&lt;0.05], [(7.64±3.17)%vs(1.85±2.51)%; P&lt;0.05]. The contents of p-mTOR in CD33+ cell in the patients treated with imatinib were higher than that of the group with HU+IFN [(10.61±13.70)%vs(3.67±4.59)%; P&lt;0.05], could be reduced by RAPA [(10.61±13.70)%vs(3.86±8.99)% GP&lt;0.05]. p-mTOR in CD33+ cell exceeded the 95% confidence interval of primary CML in 25.7% of patients treated with imatinib, and it was reduced by RAPA [(29.89±14.89)%vs(8.26±15.45)% GP&lt;0.05]. There were no difference in the contents of p-mTOR in CD33+ cell between HU+IFN group and the primary CML [(3.67±4.59)%vs(9.53±7.87)%, P&lt;0.05]. Compared to the primary CML, the contents of p-S6 in CD33+ cell of the patients treated with imatinib was not significant different [(7.64±3.17)%%vs(19.65±30.19) GP&gt;0.05], while it was lower in the patients treated with HU+IFN [(7.64±3.17)%%vs(2.95±2.70) GP&lt;0.05]. p-S6 in CD33+ cell exceeded the 95% confidence interval of primary CML in 25.7% of patients treated with imatinib, and it was reduced by RAPA [(44.48±19.43)%vs(10.53±12.39)%, P&lt;0.05]. RAPA did not influence the expression of IFN-γ in CD3+, CD3+CD8− and CD3+CD8+T cell in patients with higher levels of p-mTOR/p-S6 [(24.69±10.86)%vs(24.32±12.08)% GP&gt;0.05], [(18.79±8.72)%vs(17.0±6.53)% GP&gt;0.05], [(31.59±12.86)%vs(30.45±14.99)% GP&gt;0.05]. p-mTOR and p-S6 in CD33+ cell exceeded the 95% confidence interval of the primary CML group were found in 2 cases (20%) in imatinib resistant group, and could be reduced by RAPA in vitro.
RAPA did not influence the expression of IFN-γ in CD3+, CD3+CD8− and CD3+CD8+T cell in these 2 patients.
Conclusion:
The mTOR/S6 signal transduction pathway in CD33+ cell was activated in primary CML patients, and could be blocked by RAPA. In some patients treated with imatinib, the mTOR/S6 signal transduction pathway in CD33+ cell increased, also could be blocked by RAPA. In minority of patients resistant to imatinib, the mTOR/S6 signal transduction pathway in CD33+ cell was activated, and it might participate the resistance to imatinib.
RAPA could block it. RAPA did not impact on the immunity of T cell of patients with CML.