Breviscapine inhibits the proliferation and immune escape of diffuse large B-cell lymphoma cells by regulating JAK2/STAT3/PD-L1 pathway

The context of the article: Diffuse large B-cell lymphoma (DLBCL) is the most common pathological type of non-Hodgkin lymphoma. Breviscapine is an active ingredient of Flavonoids extracted from breviscapus. However, the role of Breviscapine in DLBCL remains unclear.

Objective: We aimed to clarify the Breviscapine impact on DLBCL.

Materials and methods: The toxic effect of Breviscapine on GM12878 cells and DLBCL cells was verified by Cell Counting Kit-8 (CCK-8) analysis. The function of Breviscapine in DLBCL was assessed using CCK-8, Hoechst staining, Western blot, Enzyme-Linked Immunosorbent Assay (ELISA), Lactate Dehydrogenase (LDH) cytotoxicity analysis, and flow cytometry. Also, the role of Breviscapine in vivo was determined by hematoxylin-eosin, TUNEL staining, immunohistochemical, and Western blot in tumor xenograft model.

Results and discussion: Breviscapine was nontoxic to GM12878 cells when the Breviscapine dose was ≤200 μM. Functionally, Breviscapine weakened DLBCL cell proliferation (IC50 = 52.62 μM for U2932 cells, and IC50 = 39.74 μM for OCI-LY3 cells) and induced cell Apoptosis. Also, Breviscapine repressed DLBCL cell immune escape by reducing PD-L1 expression in DLBCL cells, raising TNF-α and IFN-γ levels in DLBCL cells and CD8⁺ T cell co-culture supernatant, but decreasing CD8⁺T cell Apoptosis. Mechanistically, Breviscapine inactivated JAK2/STAT3/PD-L1 in DLBCL cells. Meanwhile, Breviscapine restrained DLBCL cell growth and immune escape, but these impacts were abolished after JAK2 overexpression. Furthermore, Breviscapine reduced the tumor growth, tumor volume and weight, decreased PD-L1, p-JAK2 and p-STAT3 levels, but increased IFN-γ levels in mice.

Conclusion: Breviscapine repressed DLBCL cell growth and immune escape via inactivating JAK2/STAT3/PD-L1.

Breviscapine; DLBCL; JAK2/STAT3/PD-L1; immune escape; proliferation.