SENEX-mediated CDK4/6 inhibition promotes senescence and confers apoptosis resistance in B-cell non-Hodgkin lymphoma

Background:The primary cause of treatment failure in patients with refractory or relapsed B-cell non-Hodgkin lymphoma(r/r B-NHL)is resistance to current therapies,and therapy-induced senescence(TIS)stands out as a crucial mechanism contributing to tumor drug resistance.Here,we analyzed SENEX/Rho GTPase Activating Protein 18(ARHGAP18)expression and prognostic significance in doxorubicin-induced B-NHL-TIS model and r/r B-NHL patients,investigating its target in B-NHL cell senescence and the effect of combining specific inhibitors on apoptosis resistance in B-NHL-TIS cells.Methods:Raji cells were transfected with the human SENEX shRNA recombinant lentiviral vector(Sh-SENEX)and the empty vector negative(NC)to construct a stable transfection cell line with knockdown of SENEX.Effect of SENEX-silencing on B-NHL-TIS formation,cell function and cell cycle-related pathways was analyzed.Using doxorubicin(DOX)-inducible senescent B-NHL cells combined with the specific cyclin dependent kinase 4/6(CDK4/6)inhibitor Palbociclib to observe that blocking CDK4/6 effects on TIS formation.SENEX expression of 21 B-NHL patients and 8 healthy controls were analyzed by qRT-PCR,and the correlation between its expression and clinical indicators were evaluated.Results:The downregulation of SENEX expression promotes G1-S phase transition and apoptosis while inhibiting cell proliferation,collectively suppressing the formation of TIS in B-NHL.Blockade of CDK4/6 promotes the DOX-induced G1 phase arrest to enhance TIS formation in B-NHL cells which can reverse the regulatory effect of silencing SENEX on B-NHL cell cycle regulation and senescence.The expression levels of SENEX were notably elevated in B-NHL patients compared to healthy controls,and Elevated expression levels of SENEX were associated with poor prognosis of B-NHL patients.Conclusions:SENEX enhances apoptosis resistance in B-NHL by inhibiting CDK4/6,thereby preventing G1-S phase transition and promoting TIS formation.