Exploring Natural Compounds Targeting PD-L1 and STAT3: Toxicogenomic Analysis, Virtual Screening, Molecular Docking,...

One of the most important targets in cancer immunotherapy is programmed cell death ligand 1 (PD-L1). Monoclonal antibodies developed for this target have disadvantages due to their low bioavailability and some immune-related adverse effects. Additionally, small molecules targeting PD-L1 are still in the experimental stage. At this point, discovering non-toxic natural compounds that directly or indirectly target PD-L1 is essential. In this in silico study, a comprehensive literature search was conducted to identify publications reporting the master regulator of PD-L1, which was suggested as a Signal Transducer and Activator of Transcription 3 (STAT3). The relationship between STAT3 and PD-L1 was further investigated through bioinformatic analysis.

Subsequently, natural compounds targeting PD-L1 and STAT3 were screened, and compounds with suitable toxicity profiles were docked against both PD-L1 and STAT3. Following molecular docking, the selected molecules underwent DNA docking, ADMET profile analysis, and in silico assessment of biological activities. The relationship between PD-L1 and STAT3 was determined in 52 out of the 453 articles, and it was further demonstrated in genegene interactions. Following the virtual screening, 76 natural compounds were identified, and after pre-filtering based on physicochemical properties, drug-likeness, and ADMET profiles, 29 compounds remained.

Subsequent docking revealed that two compounds, 6-Prenylapigenin, and Gelomulide J, persisted. ADMET and biological activity prediction results suggested that 6-Prenylapigenin is non-toxic and has the potential to inhibit PD-L1 and STAT3 in silico. The present study highlights that STAT3 serves as the master regulator of PD-L1, and it further suggests that 6- Prenylapigenin exhibits the potential to modulate PD-L1 and/or STAT3.

This finding could pave the way for the development of small molecules designed to block the PD-1/PD-L1 interaction by silencing the PD-L1 and/or STAT3 genes or reducing protein levels.