ATRA-induced HL-60 myeloid leukemia cell differentiation depends on the CD38 cytosolic tail needed for membrane localization, but CD38 enzymatic activity is unnecessary

Abstract

Leukocyte antigen CD38 expression is an early marker of all-trans retinoic acid (ATRA) stimulated differentiation in the leukemic cell line HL-60. It promotes induced myeloid maturation when overexpressed, whereas knocking it down is inhibitory. It is a type II membrane protein with an extracellular C-terminal enzymatic domain with NADase/NADPase and ADPR cyclase activity and a short cytoplasmic N-terminal tail. Here we determined whether CD38 enzymatic activity or the cytoplasmic tail is required for ATRA-induced differentiation. Neither a specific CD38 ectoenzyme inhibitor nor a point mutation that cripples enzymatic activity (CD38 E226Q) diminishes ATRA-induced differentiation or G1/0 arrest. In contrast a cytosolic deletion mutation (CD38 Δ11–20) prevents membrane expression and inhibits differentiation and G1/0 arrest. These results may be consistent with disrupting the function of critical molecules necessary for membrane-expressed CD38 signal transduction. One candidate molecule is the Src family kinase Fgr, which failed to undergo ATRA-induced upregulation in CD38 Δ11–20 expressing cells. Another is Vav1, which also showed only basal expression after ATRA treatment in CD38 Δ11–20 expressing cells. Therefore, the ability of CD38 to propel ATRA-induced myeloid differentiation and G1/0 arrest is unimpaired by loss of its ectoenzyme activity. However a cytosolic tail deletion mutation disrupted membrane localization and inhibited differentiation. ATRA-induced differentiation thus does not require the CD38 ectoenzyme function, but is dependent on a membrane receptor function.

The CD49d/CD29 complex is physically and functionally associated with CD38 in B-cell chronic lymphocytic leukemia cells

“…Notably, a similar association between CD38 and Vav-1 has been reported to promote cell growth and differentiation in a human myeloblastic leukemia cell model. 45 Microenvironmental interactions in bone marrow and secondary lymphoid organs confer growth advantages and extend CLL cell survival. For these reasons they are deemed to be critical in disease progression and resistance to therapy.…”

The synergistic antitumor effects of all-trans retinoic acid and C-phycocyanin on the lung cancer A549 cells in vitro and in vivo

“…All-trans retinoic acid, a derivative of vitamin A, exhibits great effects on cell differentiation (Chen et al, 2009;Congleton et al, 2011;Hung et al, 2008). In acute promyelocytic leukemia (APL), ATRA is a potent inducer of APL cell differentiation.…”

CD38 and chronic lymphocytic leukemia: a decade later

“…45 How these varied functional activities can be conducted by a single molecule is yet to be defined. A hypothesis is that they are completely unrelated as enzymatic mutants and enzyme inhibition of CD38 does not impact receptor functions 46,47 in human B, T, and myeloid cells. An alternative is that the enzymatic functions are regulated through interactions taking place between CD38 and different proteins.…”