Proteomic Changes in Cancer Cell Lines as a Result of Bacterial Infection.

Bacterial infections have been implicated in shaping the tumor microenvironment (TME), but their effects on cancer cell proteomes remain unexplored. In this study, we analyzed proteomic changes in melanoma (A375) and ovarian cancer (OVCAR3) cell line models following infection with Staphylococcus aureus strain USA300 or Salmonella enterica strain SL1344 using mass spectrometry-based label-free quantitative proteomics. Bacterial infection leads to widespread changes in host protein expression in the cancer cells, with levels of proteins involved in mitochondrial metabolism, RNA processing, and cellular stress response all increasing in relative abundance. In contrast, proteins involved in DNA repair, cytoskeletal structure, vesicle trafficking, and cell cycle regulation were consistently downregulated. The magnitude of the observed changes varied by the cancer cell type. Understanding these interactions may provide new directions for the role of bacteria in tumor progression and therapeutic resistance.