Design, Synthesis, and Biological Evaluation of SSE1806, a Microtubule Destabilizer That Overcomes Multidrug Resistance

Discovery and prospects of new heterocyclic Isatin-hydrazide derivative with a novel role as estrogen receptor α degrader in breast cancer cells

Introduction: Isatin, a heterocycle scaffold, is the backbone of many anticancer drugs and has previously been reported to engage multiple cellular targets and mechanisms, including angiogenesis, cell cycle, checkpoint pathways and multiple kinases. Here, we report that a novel isatin derivative, 5i, degrades estrogen receptor alpha (ERα) in estrogen-dependent breast cancer cells. This effect of the isatin nucleus has not been previously reported. Tamoxifen and fulvestrant represent standard therapy options in estrogen-mediated disease but have their own limitations. Isatin-based triple angiokinase inhibitor BIBF1120 (Nintedanib) and multikinase inhibitor Sunitinib (Sutent) have been approved by the FDA. Methods: Keeping this in view, we synthesized a series of N'-(1-benzyl-2-oxo-1, 2-dihydro-3H-indol-3-ylidene) hydrazide derivatives and evaluated them in vitro for antiproliferative activities in MCF-7 (ER+) cell line. We further investigated the effect of the most potent compound (5i) on the Erα through Western Blot Analysis. We used in silico pharmacokinetics prediction tools, particularly pkCSM tool, to assess the activity profiles of the compounds. Results and discussion: Compound 5i showed the best antiproliferative activity (IC50 value; 9.29 ± 0.97 µM) in these cells. Furthermore, 5i downregulated ERα protein levels in a dose-dependent manner in MCF-7. A multifaceted analysis of physicochemical properties through Data Warrior software revealed some prominent drug-like features of the synthesized compounds. The docking studies predicted the binding of ligands (compounds) with the target protein (ERα). Finally, molecular dynamics (MD) simulations indicated stable behavior of the protein-ligand complex between ERα and its ligand 5i. Overall, these results suggest that the new isatin derivative 5i holds promise as a new ERα degrader.

Synthesis and characterization of bis-amide SSE1917 as a microtubule-stabilizing anticancer agent

Microtubule dynamics are critical for spindle assembly and chromosome segregation during cell division. Pharmacological inhibition of microtubule dynamics in cells causes prolonged mitotic arrest, resulting in apoptosis, an approach extensively employed in treating different types of cancers. The present study reports the synthesis of thirty-two novel bis-amides (SSE1901-SSE1932) and the evaluation of their antiproliferative activities. N-(1-oxo-3-phenyl-1-(phenylamino)propan-2-yl)benzamide (SSE1917) exhibited the most potent activity with GI50 values of 0.331 ± 0.01 µM in HCT116 colorectal and 0.48 ± 0.27 µM in BT-549 breast cancer cells. SSE1917 stabilized microtubules in biochemical and cellular assays, bound to taxol site in docking studies, and caused aberrant mitosis and G2/M arrest in cells. Prolonged treatment of cells with the compound increased p53 expression and triggered apoptotic cell death. Furthermore, SSE1917 suppressed the growth of both mouse and patient-derived human colon cancer organoids, highlighting its potential therapeutic value as an anticancer agent.

Novel GSH-responsive prodrugs derived from indole-chalcone and camptothecin trigger apoptosis and autophagy in colon cancer

Antineoplastic agents that target tubulin have shown efficacy as chemotherapeutic drugs, yet they are often constrained by multidrug resistance (MDR) and unwanted side effects. A multi-targeted strategy demonstrates great potency in reducing toxicity and enhancing efficacy and provides an alternative way for attenuating MDR. In this study, a series of dual-targeted anti-cancer agents based on indole-chalcone derivatives and the camptothecin (CPT) scaffold were synthesized. Among them, 14-1 demonstrated superior anti-proliferative activity than its precursor 13-1, CPT or their physical mixtures against tested cancer cells, including multidrug-resistant variants, while exhibited moderate cytotoxicity toward human normal cells. Mechanistic studies revealed that 14-1 acted as a glutathione-responsive prodrug, inducing apoptosis by substantially enhancing intracellular uptake of CPT, inhibiting tubulin polymerization, increasing the accumulation of intracellular reactive oxygen species, and initiating a mitochondrion-dependent apoptotic pathway. Moreover, 14-1 notably induced autophagy and suppressed topoisomerase I activity to further promote apoptosis. Importantly, 14-1 displayed potent inhibitory effect on tumor growth in paclitaxel (PTX)-resistant colorectal cancer (HCT-116/PTX) xenograft models without inducing obvious toxicity compared with CPT- or combo-treated group. These results suggest that 14-1 holds promise as a novel candidate for anti-cancer therapy, particularly in PTX-resistant cancers.