Thiophosphopeptides Instantly Targeting Golgi Apparatus and Selectively Killing Cancer Cells

Abstract

Golgi apparatus is emerging as a key signaling hub of cells, but there are few approaches for targeting Golgi and selectively killing cancer cells. Here we show an unexpected result that changing an oxygen atom of the phosphoester bond in phosphopeptides by a sulfur atom enables instantly targeting Golgi apparatus (GA) and selectively killing cancer cells by enzymatic self-assembly. Specifically, conjugating cysteamine S-phosphate to the C-terminal of a self-assembling peptide generates a thiophosphopeptide. Being a substrate of alkaline phosphatase (ALP), the thiophosphopeptide undergoes rapid ALP-catalyzed dephosphorylation to form a thiopeptide that self-assembles. The thiophosphopeptide enters cells via caveolin-mediated endocytosis and macropinocytosis and instantly accumulates in GA because of dephosphorylation and formation of disulfide bonds in Golgi. Moreover, the thiophosphopeptide, targeting Golgi, potently and selectively inhibits cancer cells (e.g., HeLa) with the IC50 (about 3 μM), which is an order of magnitude more potent than that of the parent phosphopeptide. This work, as the first report of thiophosphopeptide for targeting Golgi, illustrates a new molecular platform for designing enzyme responsive molecules that target subcellular compartment for functions.