Deubiquitinase TRIM44 Promotes Autophagy-Mediated Chemoresistance in Diffuse Large B Cell Lymphoma

Diffuse large B cell lymphoma (DLBCL) is the most common subtype of non-Hodgkin lymphoma. Tripartite motif containing 44 (TRIM44) belonging to the TRIM family, is involved in tumor development and is highly expressed in a variety of tumors. However, the role of TRIM44 in DLBCL remains undefined. Gain and loss-of-function studies were performed on lymphoblast cell lines DB and SU-DHL-4 to investigate its function. TRIM44 overexpression significantly promoted cell proliferation and viability, whereas its silencing inhibited proliferation and induced apoptosis. TRIM44 overexpression upregulated the LC3II/LC3-I ratio and Beclin1 expression, as well as increased autophagosomes formation, suggesting autophagy activation. Notably, TRIM44 conferred chemoresistance to doxorubicin in DB cells by increasing autophagic activity. In vivo study on mice revealed that TRIM44 overexpression increased Ki67 and PCNA expression, suggesting an increased tumor growth. Our previous work revealed that miR-665 is a tumor suppressor in DLBCL. The results of miRNA pull-down and luciferase reporter assay indicated that TRIM44 was a direct target of miR-665. In conclusion, TRIM44 promoted DLBCL progression by increasing autophagy-mediated chemoresistance, revealing the involvement of miR-665/TRIM44 axis.