Thiadiazolo-Triazolo-Pyrimidine Hybrids as Dual Aurora A/ERK Inhibitors: Design, Synthesis, and Apoptotic Activity

Aberrant activation of Aurora A kinase causes mitotic spindle assembly, chromosome segregation, and cell cycle progression, leading to genomic instability as well as disruption of several tumor suppressors. Furthermore, ERK has largely emerged as a survival signaling pathway controlling cell proliferation, differentiation, and metastasis. Unfortunately, this pathway is overexpressed in most of the human malignancies. In efforts to develop innovative inhibitors targeting Aurora A/ERK signaling pathway, a novel series of thiadiazolo-, triazolo-pyrimidine hybrids have been designed, synthesized, and assessed for their ability to block Aurora A/ERK and induce apoptosis. Cytotoxicity of the synthesized hybrids was examined against MCF-7, HCT-116 and A549 cell lines. Among the synthesized hybrids, 9a, 9c, and 14b demonstrated higher cytotoxic action than alisertib and GDC-0994 against the MCF-7 and A549 cancer cell lines. IC₅₀ values for these hybrids were 2.59 ± 0.13, 4.63 ± 0.25, and 5.77 ± 0.38, respectively, against MCF-7 cell line and were 3.61 ± 0.19, 3.85 ± 0.21, and 4.23 ± 0.15, respectively, against A549. The selected hybrids significantly suppressed p-Aurora A kinase level as well as p-ERK1/2 level and its upstream regulators p-SRC, p-c-RAF, p-MEK1/2; meanwhile, ERK downstream effectors FOXO3a level was upregulated, and c-Myc was downregulated, in a dose-dependent manner. The selected hybrids significantly decreased the expression of Bcl-2 protein while increasing the levels of p53, caspase-7, caspase-9, and Bax. They effectively induced pre-G1 phase, G0/G1 phase apoptosis, and G2/M phase arrest. The synthesized hybrids possessed favorable binding interactions in the molecular docking investigations as well as appropriate drug-like characteristics.