The Role Of Molecular Pathogenesis Of The Activation Of PI3K/AKT/mTOR Signaling Pathway And The Pre-clinical Study Of Targeted Therapy In Diffuse Large B Cell Lymphoma

PRAT IActivation of the PI3K/AKT/mTOR pathway in diffuselarge B cell lymphoma and its clinical significanceBackgroundDiffuse large B-cell lymphoma (DLBCL) represents the most common subtypeof non-Hodgkin lymphoma and accounts for approximately30%of newly diagnosedlymphoid neoplasms in Western countries, and40–50%in China. A betterunderstanding of the biology of DLBCL is needed for the development of potentialtherapeutic agents that target specific intracellular pathways.MethodsIn this study, expression of the important components of the PI3K/AKT/mTORsignaling pathway and their clinical significance were investigated in73DLBCLcases. The effect of rituximab alone or combined with the PI3K/AKT/mTOR pathwayinhibitor rapamycin was further evaluated in the DLBCL cell lines.ResultsA total of73patients were identified, including45men and28women aged18to78years (median age50years). Of these patients, p-AKT was positive in40cases (54.8%), p-p70S6K in34cases (46.6%) and p-4E-BP1in33cases (45.2%).Activation of the PI3K/AKT/mTOR pathway was related to poor disease outcome inDLBCL patients treated with CHOP but not in those treated with R-CHOP. Rituximabcombined with rapamycin synergically downregulated the PI3K/AKT/mTORsignaling pathway. Western blot analysis revealed a baseline activation status of thePI3K/AKT/mTOR pathway in DLBCL cell lines, with high levels of p-AKT, p-mTOR,in addition to downstream molecules p-p70S6K and p-4E-BP1.ConclusionsThe results indicate that the PI3K/AKT/mTOR pathway is a potentiallyimportant signaling route and an unfavorable prognostic factor for DLBCL. Patientswith PI3K/AKT/mTOR activation experience a more rapidly deteriorating clinicalcourse with poor treatment response and decreased survival time. Addition ofrituximab could downregulate PI3K/AKT/mTOR activation, reversing its negativeeffect on chemotherapy-treated patients. In addition, our results indicate that thecombination of rituximab and inhibition of the activated PI3K/AKT/mTOR pathwaycould be a promising target for DLBCL therapeutic intervention in the future. PRAT IICombination of Rituximab and the mTOR inhibitoreverolimus in Diffuse large B cell lymphomaWe evaluated the effects of the anti-CD20monoclonal antibody rituximab incombination with a mammalian target of mTOR inhibitor everolimus for treatingdiffuse large B cell lymphoma (DLBCL). The combination of rituximab andeverolimus was more effective for inhibiting cell growth compared with the effect of asingle-agent therapy. An increase in G0/G1cell cycle arrest and an increasedpopulation of cells in apoptosis were observed in the combination treatment group.Addition of rituximab reduced the overexpression of p-AKT caused by the negativefeedback loop of everolimus and had an enhanced effect on inhibiting mTORsignaling, thus providing a rationale for this synergistic effect. Furthermore,combination treatment was also more effective than treatment with either agent alonefor inhibiting the growth of DLBCL xenografts. Our study provided preclinicalevidence and a theoretical basis for combination therapy for DLBCL with rituximaband everolimus in DLBCL. PRAT IIIThe in vitro anticancer activity of a novel dual PI3K/mTORinhibitor NVP-BEZ235in diffuse large B-cell lymphomaObjectiveTo investigate the anticancer activity of a novel dual PI3K/mTOR inhibitorNVP-BEZ235in diffuse large B-cell lymphoma cell lines in vitro.MethodsThe CCK-8assay was used to observe the cell proliferation. The FlowCytometry was performed to exam the cell cycle and apoptosis. The protein’sexpression level of the PI3K/AKT/mTOR signaling pathway, cell cycle proteins andapoptosis proteins were detected by Western blot.ResultsNVP-BEZ235inhibited the proliferation of the diffuse large B-cell lymphomacell lines SUDHL-4and DB in dose dependent; cell cycle arrest in G0/G1phase andpromote apoptosis. The Western blot showed that NVP-BEZ235could decrease theexpression level of the PI3K/AKT/mTOR pathway downstream targets and cell cyclerelated protein, and increase the level of apoptotic associated protein.ConclusionThe dual PI3K/mTOR inhibitor NVP-BEZ235could inhibit the proliferation andpromote the apoptosis in diffuse large B-cell lymphoma cell lines SUDHL-4and DBin vitro.