An Effective Model of the Retinoic Acid Induced HL-60 Differentiation Program

Abstract

In this study, we present an effective model All-Trans Retinoic Acid (ATRA)-induced differentiation of HL-60 cells. The model describes reinforcing feedback between an ATRA-inducible signalsome complex involving many proteins including Vav1, a guanine nucleotide exchange factor, and the activation of the mitogen activated protein kinase (MAPK) cascade. We decomposed the effective model into three modules; a signal initiation module that sensed and transformed an ATRA signal into program activation signals; a signal integration module that controlled the expression of upstream transcription factors; and a phenotype module which encoded the expression of functional differentiation markers from the ATRA-inducible transcription factors. We identified an ensemble of effective model parameters using measurements taken from ATRA-induced HL-60 cells. Using these parameters, model analysis predicted that MAPK activation was bistable as a function of ATRA exposure. Conformational experiments supported ATRA-induced bistability. Additionally, the model captured intermediate and phenotypic gene expression data. Knockout analysis suggested Gfi-1 and PPARg were critical to the ATRAinduced differentiation program. These findings, combined with other literature evidence, suggested that reinforcing feedback is central to hyperactive signaling in a diversity of cell fate programs.

GW5074 and PP2 kinase inhibitors implicate nontraditional c-Raf and Lyn function as drivers of retinoic acid-induced maturation

“…1C). GW5074 was used at a concentration previously determined to not induce growth arrest when treated alone in wild-type HL-60 [21]. …”

“…c-Raf propels RA-induced differentiation [12,19] but induced phosphorylation at the c-Raf activating sites S338 and Y340/Y341 cannot be detected in RA-treated HL-60 [20,21]. Instead, phosphorylation occurs at the S259 putative inhibitory site [22], the S621 putative stability site [23] and the S289/296/301 c-Raf sites [24,25].…”

Axolotl Ambystoma mexicanum extract induces cell cycle arrest and differentiation in human acute myeloid leukemia HL-60 cells

“…11 The morphological changes including chromatin condensation and decreased nucleocytoplasmic ratio after AXO treatment are similar to those seen following treatment with organic plant extracts such as coumarin, arsantin (a sesquiterpene lactone compound present in Artemisia santolina), and the differentiation-inducing agent, all-trans retinoic acid (ATRA). [12][13][14] AXO-treated cells resemble early committed precursors and as such would continue to divide before acquiring a fully differentiated state. This is reflected in the reduced rate of cell proliferation when compared to untreated cells and an increase in the G0/G1 peak but without complete inhibition of proliferation.…”

Retinoic acid and 6-formylindolo(3,2-b)carbazole (FICZ) combination therapy reveals putative targets for enhancing response in non-APL AML

“…This myeloblastic leukemia model cell line does not harbor any RARα mutations or fusion proteins, yet is highly responsive to RA, which induces differentiation of blasts into neutrophils. RA-induced differentiation requires sustained activation of MAPK signaling [5][6][7][8][9], and involves kinases, adaptors, and GEF signaling regulatory molecules, including the Lyn and Fgr Src-family protein tyrosine kinases (SFKs), PI3K, c-Cbl, SLP76, Vav1, as well as the aryl hydrocarbon receptor (AhR) transcription factor, here performing a putative novel cytosolic signaling function [4,[10][11][12][13][14]. These factors are embedded in a signalsome which is activated by RA to drive differentiation.…”

“…Our laboratory has described an RA-driven signalsome that propels RA-induced differentiation and maturation in the patient-derived HL-60 myeloblastic cell line [3,8,19,20]. We recently clarified that HL-60 serves as a faithful model system for an RA-responsive subtype of non-APL AML, which is still not well characterized because of its novelty [3].…”