Abstract
Clear cell renal cell carcinoma (ccRCC) is the most common subtype of kidney cancer and remains challenging to treat because of its high molecular heterogeneity, intrinsic resistance to conventional chemotherapy, and limited response to standard therapeutic approaches. Although tyrosine kinase inhibitors (TKIs) have improved clinical outcomes, many patients eventually develop drug resistance, highlighting the need for novel targeted therapies. Recent advances in transcriptomic profiling and gene co-expression network analyses have identified BUB1B (BUB1 Mitotic Checkpoint Serine/Threonine Kinase B) as a promising molecular target involved in ccRCC progression and survival.
In this study, 27 novel derivatives of TG-101209 were designed, synthesized, and evaluated as potential BUB1B modulators for the treatment of ccRCC. The chemical structures of all synthesized compounds were confirmed using ¹H NMR, ¹³C NMR, and mass spectrometry, ensuring their structural integrity before biological evaluation. To investigate their therapeutic potential, the compounds were tested in the Caki-1 human clear cell renal cell carcinoma cell line, with a primary focus on their ability to regulate BUB1B expression and reduce cancer cell viability.
Computational molecular docking studies were performed using the Schrödinger Maestro software platform to predict the binding interactions between the synthesized compounds and the target protein. In parallel, structure–activity relationship (SAR) analysis was conducted to determine how structural modifications influenced biological activity. Among the 27 synthesized derivatives, three compounds—13a, 5i, and 5j—demonstrated superior biological performance. These compounds effectively downregulated BUB1B expression, leading to significant inhibition of tumor cell growth and induction of both apoptosis and necrosis, indicating their ability to trigger programmed and non-programmed cell death pathways.
The antiproliferative activities of the lead compounds were quantified by determining their half-maximal inhibitory concentration (IC₅₀) values. Compound 13a exhibited the greatest potency, with an IC₅₀ value of 2.047 μM, followed by compound 5j (6.985 μM) and compound 5i (10.046 μM). These low micromolar IC₅₀ values indicate strong inhibitory effects on ccRCC cell viability and suggest that these compounds possess considerable therapeutic potential.
Overall, the findings demonstrate that selective targeting of BUB1B using newly synthesized TG-101209 derivatives represents a promising strategy for the treatment of clear cell renal cell carcinoma. Compared with currently available tyrosine kinase inhibitors, these compounds may provide improved therapeutic efficacy by directly interfering with a key molecular pathway involved in tumor progression. The integration of medicinal chemistry, computational modeling, and biological validation in this study provides a strong foundation for further optimization and preclinical development of BUB1B-targeted anticancer agents. These results support the continued exploration of targeted molecular therapies as an effective approach for overcoming drug resistance and improving treatment outcomes in patients with ccRCC.
