American Association for Cancer Research
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Supplementary Figure S7 from LNS8801 inhibits Acute Myeloid Leukemia by inducing the production of reactive oxygen species and activating the endoplasmic reticulum stress pathway

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posted on 2023-07-19, 13:00 authored by Inyoung Lee, Miriam Doepner, Jillian S Weissenrieder, Ariana D Majer, Sophia Mercado, Angela Estell, Christopher A Natale, Pamela J Sung, J. Kevin Foskett, Martin Carroll, Todd W Ridky

Supplementary Figure S7. LNS8801-induced AML inhibition is independent of classical GPER signaling (A) Annexin V+ flow cytometry analysis of U937 cells treated with 250nM LNS8801, 10uM Forskolin, 100uM EPAC-specific cAMP (8-pCPT-2'-O-Me-cAMP), and 100uM PKA-specific cAMP (N6-benzoyl-cAMP). Cells were incubated for 24 hours. 3 replicates per condition were used. (B) Detection of intracellular calcium upon drug treatment via a spectrofluorimeter assay. Fura2-AM dye was used for detection. 25nM E2, 250nM LNS8801, 1uM Ionomycin, 2uM thapsigargin, and 100uM histamine were used. 3 replicates were used per condition.



Despite recent therapeutic advances, the 5-year survival rate for adults with acute myeloid leukemia (AML) is poor and standard of care chemotherapy is associated with significant toxicity, highlighting the need for new therapeutic approaches. Recent work from our group and others established that the G protein-coupled estrogen receptor (GPER) is tumor suppressive in melanoma and other solid tumors. We performed a preliminary screen of human cancer cell lines from multiple malignancies and found that LNS8801, a synthetic pharmacologic agonist of GPER currently in early phase clinical trials, promoted apoptosis in human AML cells. Using human AML cell lines and primary cells, we show that LNS8801 inhibits human AML in preclinical in vitro models, while not affecting normal mononuclear cells. Although GPER is broadly expressed in normal and malignant myeloid cells, this cancer specific LNS8801-induced inhibition appeared to be independent of GPER signaling. LNS8801 induced AML cell death primarily through a caspase dependent apoptosis pathway. This was independent of secreted classical death receptor ligands, and instead required induction of reactive oxygen species (ROS) and activation of endoplasmic reticulum (ER) stress response pathways including IRE1a. These studies demonstrate a novel activity of LNS8801 in AML cells and show that targeting ER stress with LNS8801 may be a useful therapeutic approach for AML.