Diffuse Large B-Cell Lymphoma is a prevalent, aggressive subtype of Non-Hodgkin’s lymphoma (NHL), characterized by uncontrolled B-cell proliferation. While the 5-year survival rate for NHL patients is relatively favorable (80-85%), a significant subset (20-30%) experiences relapse, posing challenges in terms of treatment options. Although autologous CAR-T cell therapies have gained approval for DLBCL, there’s growing interest in allogeneic therapies like Natural Killer (NK) cell-based treatments.
Cancer cells, including DLBCL, deploy various strategies to evade immune recognition. Recent studies have indicated that targeting Inhibitor of Apoptosis Proteins (IAPs) can overcome immune evasion in certain myeloid malignancies, such as acute/chronic myeloid leukemia, B-ALL, etc. However, our knowledge regarding the role of IAPs in NHL and their potential sensitization mechanism to NK-mediated killing is limited.
This study aimed to investigate whether the inhibition of cellular IAP1/2 with a SMAC mimetic molecule could sensitize NHL cells to NK-mediated cytotoxicity and unravel the underlying molecular mechanisms. Our findings indicate that low-dose birinapant treatment prompts rapid degradation of cIAPs in NHL cells. However, longer exposure to birinapant is required to significantly enhance NK-mediated cytotoxicity, suggesting that downstream targets of cIAPs, rather than cIAPs themselves, drive NK-resistance in NHL.
Preliminary mechanistic insights reveal that cIAP inhibition leads to the downregulation of NF-kB downstream targets including FLIP, MCl-1, and Bcl-2. Moreover, the enhanced NK sensitization of NHL cells is associated with death receptor pathways, particularly TRAIL and TNF. These findings hold promise for the development of strategies to improve NK cell-based therapies for DLBCL and deepen our understanding of the molecular mechanisms underpinning this approach.
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