Target identification for natural products inhibiting oncogenic ERK/AKT signaling in malignant melanoma

Malignant melanoma is the deadliest type of skin cancer driven by high mutation rates arising in both MAPK/ERK and PI3K/AKT signaling pathways. While targeted therapies show initial promise, drug resistance develops quickly, leaving patients with limited options. Novel treatments are therefore urgently needed. As part of a broader drug discovery effort, we conducted two screening campaigns: one using our in-house library of 2,576 crude extracts, and another one leveraging large libraries of over 25,000 pure compounds from both natural and synthetic origin. Using a specifically developed high-content screening (HCS) assay that reports on downstream ERK and AKT activity, we identified 42 active compounds with IC 50 values below 20 μM. The current challenge focuses on identifying the molecular targets of the most promising hits – an essential step toward understanding their mode of action and therapeutic potential. However, target deconvolution remains a significant challenge, particularly for phenotypic assays. To address this, we developed a complementary strategy to explore compound-target interactions that includes computational methods, thermostability-based binding assays and selective kinase activity assays. Key kinases of the ERK-AKT network were produced using different cloning techniques and heterologous expression systems for testing in these assays. Challenges encountered in target identification and first insights into potential targets will be presented. Ultimately, we aim to advance our newly discovered inhibitors into lead compounds for future drug development [ 1 ] [ 2 ]. Publication History Article published online: 05 March 2026 © 2026. Thieme. All rights reserved. Georg Thieme Verlag KG Oswald-Hesse-Straße 50, 70469 Stuttgart, Germany