image: Figure 6: Cell cycle analysis of HL-60 WT and FGR O.E cells.
DNA histograms show FGR transfectants were enriched for relative number of G1/0 cells compared to the wt cells. Wild-type and FGR O.E cell lines were cultured for 72 h without (untreated control) or with 1 μM RA as indicated. Cell cycle distribution showing the percentage of cells in G1/G0 was analyzed using flow cytometry with propidium iodide staining at 72 h. Gates define the G1, S, and G2/M subpopulations (left to right). G1/0 arrest is indicated by an increase in the G1 peak for FGR O.E compared to wt cells. Quantification of 3 or more biological repeats is in Supplementary Figure 22.
Credit: Copyright: © 2025 Kazim et al. This is an open access article distributed under the terms of the Creative Commons Attribution License (CC BY 4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original author and source are credited.
“This study reveals that the expression of the Src-family kinase (SFK), FGR, alone can induce cell differentiation similar to RA.”
BUFFALO, NY – March 31, 2025 – A new research paper was published in Oncotarget, Volume 16, on March 21, 2025, titled “FGR Src family kinase causes signaling and phenotypic shift mimicking retinoic acid-induced differentiation of leukemic cells.”
A research team led by first author Noor Kazim and corresponding author Andrew Yen from Cornell University discovered that the FGR protein—traditionally considered a cancer-promoting molecule—can instead trigger leukemia cells to mature. This effect mirrors the response usually induced by retinoic acid (RA); a compound derived from vitamin A that is widely used in cancer therapy. Their finding presents a potential new path for therapies targeting acute myeloid leukemia (AML) and related cancers.
Acute myeloid leukemia is often treated using RA-based therapies that force immature white blood cells to mature, slowing their rapid growth. Retinoic acid works through complex signaling and gene regulation involving a group of proteins that orchestrate this transformation. In this study, the team used HL-60 cells, a model for human leukemia, and engineered them to express FGR. Surprisingly, the presence of FGR alone was enough to make these cells mature in a way almost identical to what happens with RA treatment. They began producing well-known markers of maturation such as CD38 and CD11b, generated reactive oxygen species (ROS), and expressed the inhibitor of the cell cycle, p27, all signs that the cells had shifted from a cancer-like, fast-dividing state to a more specialized, mature form.
Further analysis revealed that FGR activated a group of proteins known as the “signalsome,” which helps trigger the changes needed for cells to differentiate. This same group is typically activated by RA.
“Notably, FGR induces the expression of genes targeted by RAR/RXR, such as cd38 and blr1, even without RA.”
To test its potential use in treatment-resistant leukemias, the researchers introduced FGR into RA-resistant HL-60 cells. In these, FGR did not cause the same maturation process, which suggests that there are other problems with cell signaling that stop both the RA and FGR pathways. This result highlights the complexity of resistance mechanisms and the need for additional research.
These findings challenge the traditional view of FGR as strictly a cancer-driving protein. Instead, in this specific context, it appears to initiate anti-cancer behavior. That a single protein can reproduce the effects of a complex therapeutic compound like RA is both surprising and promising. If future research confirms this study’s results in more advanced models, FGR could become a new tool for developing therapies for AML and potentially other blood cancers.
Continue reading: DOI: https://doi.org/10.18632/oncotarget.28705
Correspondence to: Andrew Yen — ay13@cornell.edu
Keywords: cancer, cancer biology and cell cycle regulation, retinoic acid(RA), FGR Src-family-kinase, cancer differentiation-therapy, leukemia
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About Oncotarget:
Oncotarget (a primarily oncology-focused, peer-reviewed, open access journal) aims to maximize research impact through insightful peer-review; eliminate borders between specialties by linking different fields of oncology, cancer research and biomedical sciences; and foster application of basic and clinical science.
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Journal
Oncotarget
Method of Research
News article
Subject of Research
Cells
Article Title
FGR Src family kinase causes signaling and phenotypic shift mimicking retinoic acid-induced differentiation of leukemic cells
Article Publication Date
21-Mar-2025
COI Statement
Authors have no conflicts of interest to declare.