Abstract B003: Inhibition of cell growth and migration by polyisoprenylated cysteinyl amide inhibitors of a mutant KRAS Black American lung cancer cell line involves MAPK pathway activation and disruption of the cytoskeleton

Abstract

Abstract KRAS mutations are the most common oncogenic mutations in lung adenocarcinoma in Black Americans. Polyisoprenylated Cysteinyl Amide Inhibitors (PCAIs) constitute a group of potential cancer therapy agents that we designed to specifically disrupt and suppress hyperactive G-protein signaling, as caused by mutated RAS proteins. Here we investigate the effects of PCAIs on the viability, G-protein levels, downstream mediators, cytoskeletal structure, focal adhesion protein and apoptosis-related proteins on the KRAS-mutated, Black American-derived lung adenocarcinoma cell line, NCI-H23. Western blotting was used to determine the effect of the PCAIs on the phosphorylation levels of MAPK pathway enzymes. After 48-hour exposure to 5 μM of the PCAIs, 57 ± 3.6 to 150 ± 4.1 % increases of BRAF, MEK1/2, ERK1/2, and p90RSK phosphorylation along with a 60 ± 6.5 to 78 ± 4.0 % decrease of pRAF1 phosphorylation were observed, indicating significant changes in RAS signaling. Furthermore, 5 μM of NSL-YHJ-2-27 depleted the singly polyisoprenylated monomeric G-proteins RAC 1/2/3 and CDC42 by 77 ± 5.5 and 76 ± 2.0 %, respectively. The depletion of these key cytoskeletal proteins, and collapse of F-actin and vinculin punctates, may account for the observed inhibition of cell migration after 72-hour exposure to NSL-YHJ-2-27 and NSL-YHJ-2-46, respectively. The invasion area of 3D NCI-H23 spheroids after treatment with 10 μM of NSL-YHJ-2-27 and NSL-YHJ-2-46 decreased by 87 ± 0.1% and 92 ± 0.3 %, respectively. Treatment with 0.5 μM NSL-YHJ-2-27 and NSL-YHJ-2-46 caused cell rounding and reduction of mean cell areas by 30 ± 5.0 and 42 ± 0.6 %, respectively. Mean cell area occupied by vinculin punctates decreased by 51 ± 2.6 % and 31 ± 2.8 % after exposure to 0.5 μM NSL-YHJ-2-27 and NSL-YHJ-2-46, respectively. NSL-YHJ-2-27 (5 μM) depleted full-length inactive caspase 3 and 7 levels by 72 ± 5.8 and 91 ± 7.0 %, respectively. These findings show the direct effects of the PCAIs on the KRAS signaling pathway thereby supporting their continuous development as potential targeted therapies for cancers with RAS mutations. Citation Format: Kweku Ofosu-Asante. Inhibition of cell growth and migration by polyisoprenylated cysteinyl amide inhibitors of a mutant KRAS Black American lung cancer cell line involves MAPK pathway activation and disruption of the cytoskeleton [abstract]. In: Proceedings of the 16th AACR Conference on the Science of Cancer Health Disparities in Racial/Ethnic Minorities and the Medically Underserved; 2023 Sep 29-Oct 2;Orlando, FL. Philadelphia (PA): AACR; Cancer Epidemiol Biomarkers Prev 2023;32(12 Suppl):Abstract nr B003.