Probing GPX4 as a target to drive ferroptosis

Ferroptosis has become a promising target for cancer therapy.  This regulated non-apoptotic cell death process is described as an iron-dependent lipid peroxidation, specifically necessitating peroxidation of polyunsaturated fatty acid-containing phospholipids. The protective mechanism in healthy cells is for the resulting lipid hydroperoxides to be converted to the corresponding lipid alcohols by glutathione peroxidase 4 (GPX4) and that being able to target this enzyme for inhibition in cancer cells could overcome the suppression of ferroptosis.

A collaboration between groups at AbbVie, Inc. and Stanford University, led by Relja Popovic and Scott J. Dixon respectively, explored the scope for GPX4 therapeutically.

In the course of the studies a sensor of lipid peroxidation (Bodipy 581/591 C11) and DRAQ7 were used in combination to demonstrate that cells undergoing ferroptosis accumulate lipid peroxides and subsequently die, and that this could be modulated under different conditions.

What became clear with the complex investigations by the authors was that the transition from 2-D to 3-D cell culture system reduced the sensitivity of cells to GPX4 inhibition - due to a substitution by monounsaturated fatty acids in the 3D culture from the upregulation of another enzyme (SCD).  Under this 3-D culture condition, it is generally understood to recapitulate better the in vivo condition, though for this case needs to be seen as initial findings and requires further investigation.

GPX4 remains limited in its promise as a target to block suppression of ferroptosis due to these confounding data and without the means currently to specifically target cancer cell GPX4 based on another feature e.g. proliferation rate, tumour cell surface marker, etc.

Reference:

Park, V. S., Pope, L. E., Ingram, J. P., Alchemy, G. A., Purkal, J. J., Murray, M. B., ... & Popovic, R. (2025). Lipid Composition Alters Ferroptosis Sensitivity. Cancer Research. 
https://doi.org/10.1158/0008-5472.CAN-24-4207

MDS Imaging Flow Cytometry with DRAQ5

Features with MDS need to be better defined to be robust indicators of disease.  Disease experts from Lund University and Skåne Regional Laboratories show that Imaging Flow Cytometry (IFC) can provide the statistical discrimination of cellular features that are cellular hallmarks of MDS.

Notably they used DRAQ5 to trigger cellular events, widely used elsewhere.  However, they describe a new identifier of nuclear condensation utilizing the DRAQ5 signal and the Bright Detail Intensity (BDI) feature in the Imagestream's IDEAS software. DRAQ5-BDI showed that there was a definitive reduction in this feature in disease versus normal bone marrow, consistent with degree of chromatin condensation, evident in megaloblastoid cells.

Moreover, they capitalized on the DRAQ5 signal to determine nuclear aspect ratio and nuclear area features and to identify binucleated cells which were weighted towards euploid rather than double DNA status in MDS samples and the reverse in normal bone marrow, reflecting different cell cycle positions and therefore proliferation rates.

Using fresh samples (neither fixed or freeze-thaw treated) they authors were able to more faithfully preserve the integrity of a range of features to segment cell populations and observe phenotypic staining and cytoplasmic features that were also beneficial in stratifying disease.

Reference:
Despoina Violidaki, Olof Axler, Lars Nilsson, Anna Porwit, Mats Ehinger. Translation of the Morphological Hallmarks of Dyserythropoiesis to Objective Morphometric Parameters by Imaging Flow Cytometry. International Journal of Laboratory Hematology. 2025 Jul 29. DOI:10.1111/ijlh.14534