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This study investigated the cytotoxic effect of oridonin (ORI), a diterpenoid isolated from Rabdosia rubescens, in human diffuse large B cell lymphoma (DLBCL) in vitro and in vivo and the potential molecular mechanisms for ORI-induced cell apoptosis. ORI treatment caused reactive oxygen species (ROS)-mediated oxidative DNA damage response (DDR) and the c-Jun N-terminal kinase (JNK) pathway activation, leading to an induction of intrinsic apoptosis. ROS abolition blocked ORI-induced apoptosis and attenuated the expression of phospho-histone H2AX and phospho-JNK, indicating that ROS-mediated DNA damage and JNK pathway activation were involved in ORI-induced apoptosis. The systemic administration of ORI suppressed the growth of human DLBCL xenografts without showing significant toxicity. These findings suggest that ORI may have promising therapeutic application in DLBCL.

We evaluated the efficacy of the anti-CD20 monoclonal antibody rituximab in combination with the mammalian target of rapamycin (mTOR) inhibitor everolimus for treating diffuse large B-cell lymphoma (DLBCL). The combination of rituximab and everolimus was more effective for inhibiting cell growth compared with single-agent therapy. An increase in G0/G1 cell cycle arrest and an increased population of cells in apoptosis were observed in the combination treatment group. The addition of rituximab reduced the overexpression of p-AKT caused by the negative feedback loop of everolimus and had an enhanced effect on inhibition of mTOR signaling, thus providing a rationale for this synergistic effect. Furthermore, combination treatment was also more effective than treatment with either agent alone for inhibiting the growth of DLBCL xenografts. Our study provides preclinical evidence and a theoretical basis for combination therapy with rituximab and everolimus in DLBCL.

We demonstrate the synergistic antitumor effect of oridonin and the PI3K/mTOR inhibitor NVP-BEZ235 on the non-germinal center B cell-like subtype of diffuse large B cell lymphoma (non-GCB DLBCL) both in vitro and in vivo. The underlying mechanism may be multifunctional, involving apoptosis, AKT/mTOR and NF-kB inactivation, and ROS-mediated DNA damage response. Our findings pave the way for a new potential treatment option for non-GCB DLBCL with the combination of oridonin and NVP-BEZ235. Electronic supplementary material The online version of this article (doi:10.1186/s13045-016-0303-0) contains supplementary material, which is available to authorized users.