Synthesis and biological activity of 11-Oxygenated and heterocyclic estrone analogs in pancreatic cancer monolayers and 3D spheroids

Abstract

Pancreatic Ductal Adenocarcinoma (PDAC), representing over 90 % of pancreatic cancer diagnoses, is an aggressive disease with survivability among the worst of all cancers due to its difficulty in detection and its high metastatic properties. Current therapies for PDAC show limited success at extending life expectancies, primarily due to cancer resistance and lack of patient-specific targeted therapies. This work highlights the design and evaluation of estrone-derived analogs with both heterocyclic side-chain functionality and 11-oxygenated functionality for use in pancreatic cancer. First-round heterocyclic analogs show preliminary promise in AsPC-1 and Panc-1 cell lines, with IC50 values as low as 10.16 ± 0.83 µM. Their success, coupled with design choices from other studies, led to the synthesis of novel 11-hydroxyl and 11-keto estrone analogs that show potent in-vitro toxicity against various pancreatic cancer models. The three most cytotoxic analogs, KA1, KA2, and KA9 demonstrated low micromolar activities in both MTT and CellTiter assays in three pancreatic cancer cell lines: AsPC-1, Panc-1, and BxPC-3, as well as in a co-culture of Panc-1 and pancreatic stellate cells. IC50 values for KA9 (4.17 ± 0.90, 5.28 ± 1.87, and 5.70 ± 0.65 µM respectively) shows consistency in all cell lines tested. KA9 is also able to cause an increase in caspases 3 and 7 activity, key markers for apoptosis, at non-cytotoxic concentrations. Additional work was performed by generating 3D pancreatic cancer spheroids to better modulate the pancreatic tumor microenvironment, and KA9 continued to show the best IC50 values (21.0 and 24.3 µM) in both cell types tested. KA9 was also able to prevent the growth of spheroids whereas the standard chemotherapy, Gemcitabine, could not, suggesting that it may be a potent analog for future development of treatments. Molecular dynamic simulations were also performed to confirm biological findings and uncovered that KA9′s preferential binding location is in the active site pocket of key proteins involved in cytotoxicity.