Transglutaminase 2 programs differentiating acute promyelocytic leukemia cells in all-trans retinoic acid treatment to inflammatory stage through NF-κB activation

Abstract

Differentiation syndrome (DS) is a life-threatening complication arising during retinoid treatment of acute promyelocytic leukemia (APL). Administration of all-trans retinoic acid leads to significant changes in gene expression, among the most induced of which is transglutaminase 2, which is not normally expressed in neutrophil granulocytes. To evaluate the pathophysiological function of transglutaminase 2 in the context of immunological function and disease outcomes, such as excessive superoxide anion, cytokine, and chemokine production in differentiated NB4 cells, we used an NB4 transglutaminase knock-out cell line and a transglutaminase inhibitor, NC9, which inhibits both transamidase- and guanosine triphosphate-binding activities, to clarify the contribution of transglutaminase to the development of potentially lethal DS during all-trans retinoic acid treatment of APL. We found that such treatment not only enhanced cell-surface expression of CD11b and CD11c but also induced high-affinity states; atypical transglutaminase 2 expression in NB4 cells activated the nuclear factor kappa (κ)-light-chain-enhancer of the activated B-cell pathway, driving pathogenic processes with an inflammatory cascade through the expression of numerous cytokines, including tumor necrosis factor alpha (TNF-α), interleukin 1 beta (IL-1β), and monocyte chemoattractant protein 1. NC9 decreased the amount of transglutaminase 2, p65/RelA, and p50 in differentiated NB4 cells and their nuclei, leading to attenuated inflammatory cytokine synthesis. NC9 significantly inhibits transglutaminase 2 nuclear translocation but accelerates its proteasomal breakdown. This study demonstrates that transglutaminase 2 expression induced by all-trans retinoic acid treatment reprograms inflammatory signaling networks governed by nuclear factor κ-light-chain-enhancer of activated B-cell activation, resulting in overexpression of TNF-α and IL-1β in differentiating APL cells, suggesting that atypically expressed transglutaminase 2 is a promising target for leukemia treatment.

Benefits of Combined All-Trans Retinoic Acid and Arsenic Trioxide Treatment of Acute Promyelocytic Leukemia Cells and Further Enhancement by Inhibition of Atypically Expressed Transglutaminase 2

“…In earlier studies, others tested a novel irreversible TG2 inhibitor NC9 to identify agents that can selectively target cancer stem cells in tumors [13,19,20]. Our studies demonstrated that elevated protein expression of TG2 could lead to inflammatory reactions [20,21].…”

“…Endothelium damage with a capillary leak, edema, hypotension, fever, rash and dyspnea, pulmonary infiltrates, pleural or pericardial effusions and tissue infiltration may ensue [24]. In the last decade, dexamethasone or prednisolone prophylaxis has been used for the prevention of DS during the remission induction phase, but it is ineffective in reducing mortality developing from DS [25].We also previously demonstrated that shRNA-mediated knock-down or genomic deletion of TG2 in differentiating NB4 cell lines can decrease the levels of chemokines and cytokines, whose production is involved in the development of DS [20,23]. As a diminished expression of TG2 in differentiating APL cells may attenuate the ATRA-induced systemic inflammatory response syndrome…”

“…In its survival-promoting attribution, TG2 most often participates as a protein-protein interaction partner in GTP-bound form [17,18]. In earlier studies, others tested a novel irreversible TG2 inhibitor NC9 to identify agents that can selectively target cancer stem cells in tumors [13,19,20]. Our studies demonstrated that elevated protein expression of TG2 could lead to inflammatory reactions [20,21].During ATRA induced differentiation of the NB4 acute promyelocytic human leukemia cell lines TG2 is mainly expressed in the cytosol and is partly translocated to the cell nucleus [20,22].…”

“…In earlier studies, others tested a novel irreversible TG2 inhibitor NC9 to identify agents that can selectively target cancer stem cells in tumors [13,19,20]. Our studies demonstrated that elevated protein expression of TG2 could lead to inflammatory reactions [20,21].During ATRA induced differentiation of the NB4 acute promyelocytic human leukemia cell lines TG2 is mainly expressed in the cytosol and is partly translocated to the cell nucleus [20,22]. We previously demonstrated the correlation of the expression levels of TG2 and inflammatory cytokines with differentiation syndrome (DS) [20,23].DS, which develops in approximately 5-25% of patients, is a severe life-threatening condition triggered by the release of inflammatory cytokines, such as tumor necrosis factor α (TNF-α), interleukin-1β (IL-1β) and chemokines like monocyte chemoattractant protein-1 (MCP-1) (CCL2) [24].…”

“…During ATRA induced differentiation of the NB4 acute promyelocytic human leukemia cell lines TG2 is mainly expressed in the cytosol and is partly translocated to the cell nucleus [20,22]. We previously demonstrated the correlation of the expression levels of TG2 and inflammatory cytokines with differentiation syndrome (DS) [20,23].…”