Cancer cells exist in a state of Darwinian selection using mechanisms that produce changes in gene expression through genetic and epigenetic alteration to facilitate their survival. Cellular plasticity, or the ability to alter cellular phenotype, can assist in survival of premalignant cells as they progress to full malignancy by providing another mechanism of adaptation. The connection between cellular stress and the progression of cancer has been established, although the details of the mechanisms have yet to be fully elucidated. The molecular chaperone HSP90 is often upregulated in cancers as they progress, presumably to allow cancer cells to deal with misfolded proteins and cellular stress associated with transformation. The objective of this work is to test the hypothesis that inhibition of HSP90 results in increased cell plasticity in mammalian systems that can confer a greater adaptability to selective pressures. The approach used is a murine in vitro model system of hematopoietic differentiation that utilizes a murine hematopoietic stem cell line, erythroid myeloid lymphoid (EML) clone 1, during their maturation from stem cells to granulocytic progenitors. During the differentiation protocol, 80%–90% of the cells die when placed in medium where the major growth factor is granulocyte–macrophage-colony stimulating factor. Using this selection point model, EML cells exhibit increases in cellular plasticity when they are better able to adapt to this medium and survive. Increases in cellular plasticity were found to occur upon exposure to geldanamycin to inhibit HSP90, when subjected to various forms of cellular stress, or inhibition of histone acetylation. Furthermore, we provide evidence that the cellular plasticity associated with inhibition of HSP90 in this model involves epigenetic mechanisms and is dependent upon high levels of stem cell factor signaling. This work provides evidence for a role of HSP90 and cellular stress in inducing phenotypic plasticity in mammalian systems that has new implications for cellular stress in progression and evolution of cancer.
In vivo, stem cells can be found in hypoxic niches within bone marrow, peripheral blood, and umbilical cord blood. Stem cells grown in hypoxic conditions, which contains an oxygen level of up to 1%, cause them to utilize glycolysis as the primary source of energy, as opposed to stem cells cultured in normoxic conditions that use both glycolysis and oxidative phosphorylation. Differentiation requires a significant amount of energy, and previous research has shown that hydroxide radicals leaked from mitochondria inhibit phosphatases and stimulate differentiation. EML cells are a stem cell factor dependent murine hematopoietic stem cell line often used to study differentiation of blood cells. In our study, EML cells were allowed to differentiate in normoxia, chronic hypoxia and acute hypoxia conditions. We observed the effects that each of the conditions have on the differentiation kinetics by using antibodies to label the cell surface markers against: Sca‐1, CD117, CD48, CD135, CD150, CD11b, CD127, F4/80, Ter119, Ly6‐G/C. Chronic hypoxia EML cells differentiation kinetics were significantly altered. Also, labeling cells with fluorescent antibodies allowed us to trace the lineage of the induced differentiated cells, by using flow cytometry. We found that EML cells cultured in chronic hypoxic conditions had a shift in its multi‐potential progenitor (MPP) subtype, MPP4 to MPP3, that the other conditions did not. Further investing the differentiation kinetics of chronic hypoxia could lead to a better understanding on producing long term hematopoietic stem cells in vitro, for stem cell transplantation in healthcare.Support or Funding InformationMy research project began November 2017 and is ongoing, and is part of Dr. Sollars' laboratory project that is funded by NIH 1R15CA186017.This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.
hi@scite.ai
10624 S. Eastern Ave., Ste. A-614
Henderson, NV 89052, USA
Copyright © 2024 scite LLC. All rights reserved.
Made with 💙 for researchers
Part of the Research Solutions Family.