Tetracenomycin Aglycones Primarily Inhibit Cell Growth and Proliferation in Mammalian Cancer Cell Lines

Tetracenomycins are anticancer polyketides that arrest cancer cell proliferation via binding to the large mammalian ribosomal subunit near the polypeptide exit channel. The tetracenomycins are natural products that many members of the actinomycete family produce. The first goal of this study was to improve the biosynthesis of tetracenomycin analogs via metabolic engineering. The second goal was to probe more deeply into the antiproliferative activity of tetracenomycin aglycones. The tetracenomycins were assessed via several assays, including cell viability assays, clonogenic assays, and flow cytometry apoptosis assays. The data suggest that tetracenomycins C and X inhibit cell proliferation and arrest cell growth, supporting their cytostatic action mechanism. In addition, tetracenomycins C and X induced degeneration of 3D spheroid cultures and exhibited concentration-dependent inhibition of cell survival and colony formation in clonogenic assays. This work demonstrates that tetracenomycins act mainly as cytostatic rather than apoptotic agents.