Anticancer Res. 2023 May;43(5):1901-1908. doi: 10.21873/anticanres.16349.
BACKGROUND/AIM: Adult T-cell leukemia (ATL) is a peripheral T-lymphocytic malignancy influenced by human T-cell leukemia virus type 1 (HTLV-1) infection. Aggressive ATL has a poor prognosis, therefore newer agents are desperately needed. We revealed that dimethyl fumarate (DMF) causes ATL cell death via inhibition of nuclear factor-kappa B (NF-B) and signal transducer and activator of transcription 3 signaling. Here, we evaluated the specific mechanism of DMF effects on NF-B signaling in MT-2 HTLV-1-infected T-cells.
MATERIALS AND METHODS: We examined the effects of DMF on the caspase recruitment domain family member 11 (CARD11)-BCL10 immune signaling adaptor (BCL10)-mucosa-associated lymphoid tissue lymphoma translocation protein 1 (MALT1) (CBM) complex and upstream signaling molecules which are critical for NF-B signaling in MT-2 cells by immunoblotting. We also explored its effects on cell-cycle distribution. Furthermore, we assessed whether the BCL2 apoptosis regulator (BCL2)/BCL2-like 1 (BCL-xL) inhibitor navitoclax promoted the inhibitory effect of DMF on cell proliferation and apoptosis-associated proteins by trypan blue exclusion test and immunoblotting, respectively.
RESULTS: DMF inhibited constitutive phosphorylation of CARD11 followed by suppression of inhibitory-B kinase α/β phosphorylation at serine in a dose-dependent fashion in MT-2 cells. Furthermore, DMF inhibited MALT1 and BCL10 expression in the same fashion. However, DMF did not prevent the phosphorylation of protein kinase C-β, an upstream signaling molecule of CARD11. Cell-cycle analysis highlighted that DMF treatment at 75 μM resulted in the accumulation of cells at the sub-G1 and G2/M phases. Navitoclax modestly promoted DMF-induced suppression of MT-2 cells via inhibition of cellular inhibitor of apoptosis protein-2 expression and c-JUN N-terminal kinase phosphorylation.
CONCLUSION: The suppression of MT-2 cell proliferation by DMF makes its further evaluation as an innovative agent for therapy of ATL worthwhile.