TG2 and NF-κB Signaling Coordinates the Survival of Mantle Cell Lymphoma Cells via IL6-Mediated Autophagy.

Expression of the transglutaminase TG2 has been linked to constitutive activation of NF-κB and chemotherapy resistance in mantle cell lymphoma (MCL) cells. TG2 forms complexes with NF-κB components, but mechanistic insights that could be used to leverage therapeutic responses has been lacking. In the current study, we address this issue with the discovery of an unexpected role for TG2 in triggering autophagy in drug-resistant MCL cells through induction of IL6. CRISPR-mediated silencing of TG2 delayed apoptosis while overexpressing TG2 enhanced tumor progression. Under stress, TG2 and IL6 mediate enhanced autophagy formation to promote MCL cell survival. Interestingly, the autophagy product ATG5 involved in autophagosome elongation positively regulated TG2/NF-κB/IL6 signaling, suggesting a positive feedback loop. Our results uncover an interconnected network of TG2/NF-κB and IL6/STAT3 signaling with autophagy regulation in MCL cells, the disruption of which may offer a promising therapeutic strategy. Cancer Res; 76(21); 6410-23. ©2016 AACR.