Abstract 127: Oleanolic acid oxime derivatives modulate NF-κB signaling pathway leading to cell cycle arrest in pancreatic cancer cells
Authors: Narożna Maria , Krajak-Kuźniak Violetta , Kleszcz Robert , Baer-Dubowska Wanda Maria 
Published: September 2020

Chronic inflammation is considered an important risk factor in the etiology of neoplastic diseases, including pancreatic cancer (PC). Naturally occurring triterpeinoid - oleanolic acid (OA) was shown to possess anti-inflammatory and anti-tumorigenic activities in the in vitro as well as in vivo models. The limited bioavailability of OA justifies searching for its more available derivatives.

In this study novel oleanolic acid oxime derivatives (OAO) differing in substitution group at position C-17 were evaluated in the context of their possible modulating effect of NF-κB signaling pathway and subsequently cell cycle arrest and proliferation of pancreatic cancer cells - line PSN-1. PSN-1 cells were incubated with OA and OAO derivatives at the concentrations of 10µM, 20µM and 30 µM selected basing on the results of MTT assay for 24h.

The activation of NF-κB was assessed by measuring the level of binding of its active subunits p65 and p50 to specific DNA sequence using the ELISA assay, and their translocation from cytosol to nucleus by Western blot. For genes expression evaluation (NF-κB, COX-2, ERK1/2 and JNK) the RT-PCR (mRNA) and bead-based sandwich type immunoassay on the Luminex®MAGPIX instrument (protein) was applied. Muse®Cell Analyzer was used to flow cytometric assessment of cells proliferation based on Ki67 expression and the cell cycle progression was assessed by propidium iodide staining.

The OAO-morpholide derivative (18) and OAO-benzyl ester derivative (14) reduced the most efficiently the NF-κB activation and expression resulting in a diminished level of COX-2 protein in the cytosolic fraction. The expression of JNK and ERK1/2, the elements of MAPK signaling cascade, was not significantly affected by any of the tested OAO derivatives. Treatment with OAO-morpholide derivative (18) also induced the cell cycle arrest leading to accumulation of the cells in S/G2 phase. None of the tested OAO derivatives affected significantly the cells proliferation measured in term of Ki67 expression.

These results indicate that the OAO derivatives, particularly morpholide conjugates are more potent suppressors of NF-κB signaling pathway than parent OA.

The specificity of OAO structure substitution seems to be crucial for the NF-κB modulation and subsequent possible anti-inflammatory effect. Downregulation of NF-κB by these compounds does not seem to be connected with the suppression of MAPK signaling pathways.

Funding: This work was supported by Polish National Science Centre, grant 2016/21/B/NZ7/01758.

Citation Format: Maria Narożna, Violetta Krajak-Kuźniak, Robert Kleszcz, Wanda Maria Baer-Dubowska. Oleanolic acid oxime derivatives modulate NF-κB signaling pathway leading to cell cycle arrest in pancreatic cancer cells [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 127.