Using a Natural Triterpenoid to Unlock the Antitumor Effects of Autophagy in B-Cell Lymphoma

Background and Objective: Diffuse large B-cell lymphoma (DLBCL), a subtype of non-Hodgkin’s lymphoma, is the most common lymphoid malignancy in the Western world. Treatment of DLBCL has been greatly improved in recent years with the addition of the monoclonal antibody Rituximab to the gold standard CHOP (cyclophosphamide, doxorubicin hydrochloride, vincristine sulfate, and prednisone) chemotherapy regimen, but these treatments are often ineffective in patients with highly aggressive disease or patients of advanced age. While CAR-T cells have further advanced the treatment landscape of DLBCL, these often come at significant costs such as toxicity and financial costs for patients. Thus, research has recently focused on natural products that can selectively target malignant lymphomas while displaying a reduced host toxicity profile. Methods: In vitro cellular and biochemical approaches were used to analyze the effects of a natural extract from the Ganoderma lucidum mushroom (GA-DM) on autophagy and apoptosis in human and mouse B-cell lymphoma lines. In addition, in vivo approaches were applied to determine the effect of GA-DM on tumor growth and metastasis in a mouse model of B-cell lymphoma. Results: Here, we report, for the first time, that GA-DM induces apoptosis in the human B-cell lymphoma cell lines DB and Toledo, and orchestrates autophagy and apoptosis in the murine B-cell lymphoma cell line A20. While GA-DM differentially induced autophagy and apoptosis in mouse and human B-cell lymphomas, blocking apoptosis by the caspase inhibitor Z-VAD-FM reduced anti-proliferative activity in human B-cell lymphoma cells (DB: 71.6 ± 6.2% vs. 56.7 ± 2.4%; Toledo: 53.1 ± 10.6% vs. 14.6 ± 9.3%) in vitro. Antitumor efficacy of GA-DM was also investigated in vivo in a murine B-cell lymphoma model using the A20 cell line, where GA-DM treatment reduced both the number of tumor metastases (control: 5.5 ± 3.2 vs. GA-DM: 1.6 ± 0.87) and the overall tumor burden (control: 3.2 g ± 1.9 vs. GA-DM: 1.70 g ± 0.2) in diseased mice. Conclusions: These findings support the potential use of GA-DM as a novel chemotherapeutic in the treatment of DLBCL and could improve the treatment of higher-risk patients with advanced disease who cannot tolerate current chemotherapy treatments.