Effects of photodeoxygenation on cell biology using dibenzothiophene S-oxide derivatives as O(³P)-precursors

Photodeoxygenation of dibenzothiophene S-oxide and its derivatives have been used to generate atomic oxygen [O(³P)] to examine its effect on proteins, nucleic acids, and lipids. The unique reactivity and selectivity of O(³P) have shown distinct oxidation products and outcomes in biomolecules and cell-based studies. To understand the scope of its global impact on the cell, we treated MDA-MB-231 cells with 2,8-diacetoxymethyldibenzothiophene S-oxide and UV-A light to produce O(³P) without targeting a specific cell organelle. Cellular responses to O(³P)-release were analyzed using cell viability and cell cycle phase determination assays. Cell death was observed when cells were treated with higher concentrations of sulfoxides and UV-A light. However, significant differences in cell cycle phases due to UV-A irradiation of the sulfoxide were not observed. We further performed RNA-Seq analysis to study the underlying biological processes at play, and while UV-irradiation itself influenced gene expression, there were 9 upregulated and 8 downregulated genes that could be attributed to photodeoxygenation.