ω-Lipid chain-engineered tunicamycin analogues as safer antiproliferative and antimetastatic biochemicals

Tunicamycins have long served as important biochemical tools to interrogate unfolded protein responses (UPRs) in the endoplasmic reticulum by targeting DPAGT1 (dolichyl-phosphate N-acetylglucosamine-phosphotransferase 1), the first committed enzyme in N-glycan biosynthesis. Despite their utility, the broad and unselective cytotoxicity of tunicamycins has severely limited their translational and in vivo applications. We discovered that structural modification at the ω-position of the tunicamycin V (TM-V: TM-C15:1-iso) lipid chain overcomes this key limitation. Two newly designed analogues, TM-C13:0-ω-Hydroxyguanidyl (8) and TM-C13:0-ω-Guanidyl (9), demonstrated superior DPAGT1 inhibition relative to TM-V. Importantly, these analogues exhibited no detectable toxicity toward normal cells (IC₅₀ > 100 μM). In contrast, they showed potent antiproliferative activity against solid tumor cell lines (IC₅₀ = 0.53-1.54 μM), resulting in markedly improved selectivity indices (SI ≥65-192) compared with TM-V (SI = 0.46-2.2). These findings establish a new class of tunicamycin analogues that preserve the natural product core while decoupling therapeutic activity from off-target toxicity, enabling mechanistic studies of ER stress and supporting the development of well-tolerated anticancer agents.