Discovery of novel progesterone-heterocyclic conjugates and their encapsulated polymeric nanoparticles as potential CDK8 inhibitors: lung cytotoxicity evaluation, gene expression, and molecular docking

CDK8 is overexpressed in many cancers and represents a potential target for developing new anticancer agents. To identify promising antineoplastic compounds as CDK8 inhibitors, progesterone-heterocyclic conjugates were synthesized through multicomponent reactions (MCRs), verified by spectroscopic and analytical data, and they were then encapsulated into CS-PEG nanoparticles to enhance their activity and efficacy. The <i>in vitro</i> anticancer activity of synthesized progesterone heterocyclic derivatives in free and CS-PEG nanoform was assessed on A549 cells using the neutral red uptake test. Compared to Doxorubicin values (IC₅₀ = 11.74 and 10.14 μM for free and CS-PEG nanoform, respectively), compounds 4e, 4b, 4f, 13, 15, 8b, 12, and 4d, in free form (IC₅₀ = 3.63, 4.46, 5.49, 5.62, 9.54, 9.77, 10.47, and 10.96 μM, respectively) and in CS-PEG nanoform (IC₅₀ = 3.20, 3.54, 3.83, 5.28, 7.09, 9.43, 9.65, and 9.88 μM, respectively), showed higher inhibitory activity on A549 growth. Notably, compounds 4e and 4f showed significant inhibition of CDK8 enzyme <i>in vitro</i> comparable to Cortistatin A (IV). Furthermore, compounds 4e and 4f CS-PEG nanoparticles significantly downregulated the CDK8, β-catenin, c-MYC, and HIF-1α genes as well as the protein expression levels of PI3K and AKT, and also upregulated the levels of P53 gene and MDA in A549 cells, thereby triggering ROS-mediated apoptosis and suppressing angiogenesis, invasion, and cell growth. Additionally, the molecular docking study confirmed that compounds 4e and 4f had a strong binding affinity to the active site of CDK8, consistent with their results and antiproliferative activity on A549 lung cancer cells.