Abstract 2555: 14-3-3 and Smad2/3 are key mediators of atypical-PKCs in neuroblastoma progression

Abstract

Abstract Neuroblastoma (NB) is a cancer that develops in the neuroblasts. It is the most common cancer in children under the age of 1 year, accounting for approximately 6% of all cancers. The prognosis of NB is linked to both age and degree of cell differentiation. This results in a range of survival rates for patients, with outcomes ranging from recurrence and mortality to high survival rates and tumor regression. Our previous work indicated that PKC-ι promotes cell proliferation in NB cells through the PKC-ι/Cdk7/Cdk2 cascade. We report on two atypical protein kinase inhibitors as potential therapeutic candidates against BE(2)-C and BE(2)-M17 cells: a PKC-ι-specific 5-amino-1-2,3-dihydroxy-4-(methylcyclopentyl)-1H-imidazole-4-carboxamide (ICA-1S) and a PKC-ζ specific 8-hydroxy-1,3,6-naphthalenetrisulfonic acid (ζ-Stat). In the current study, we report the effects of aPKC inhibition on 14-3-3-centered signaling in NB progression. To this end we utilized various techniques such as western blotting, Flowcytometry, scratch assays and invasion assays. These assays were employed to assess the downstream implications of aPKCs and 14-3-3 attenuation on signaling pathways regulating proliferation, cell cycle regulation, apoptosis, and metastasis. Both compounds induced apoptosis and retarded the epithelial-mesenchymal transition (EMT) of NB cells. Proteins 14-3-3 and Smad2/3 acted as central regulators of aPKC-driven progression in BE(2)-C and BE(2)-M17 cells in relation to the Akt1/NF-κB and TGF-β pathways. We demonstrate the downstream effects of aPKC attenuation on aPKC phosphorylation, the Akt1/NF-κB pathway, the Cdk7/Cdk2 pathway and EMT in relation to 14-3-3 and Smad2/3. We have analyzed the expression of EMT markers including Vimentin, a mesenchymal marker that is a hallmark of cancer metastasis. Data indicates that aPKCs upregulate Akt1/NF-κB and TGF-β pathways in NB cells through an association with 14-3-3 and Smad2/3 that can be diminished by aPKC inhibitors. In summary, both inhibitors appear to be promising potential neuroblastoma therapeutics and merit further research. Citation Format: Sloan Breedy, Wishrawana S. Ratnayake, Luke Lajmi, Robert Hill, Mildred Acevedo-Duncan. 14-3-3 and Smad2/3 are key mediators of atypical-PKCs in neuroblastoma progression [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 2555.