The MDA-MB-231 Breast Cancer Cell Secretomes Modify Metabolomes of Pseudomonas aeruginosa Breast Microbiome

Breast cancer (BC) is globally becoming a great challenge, being both the most diagnosed cancer and the leading cause of death in women. In addition to cancer cells, many bacteria co-inhabit BC, which differ in type and number from the resident microbiota found in healthy breast tissue. While many reports have demonstrated the ability of different bacteria to dysregulate BC's metabolites, the reciprocal effect of these metabolites on the bacterial microbiota has not yet been investigated. Herein, we assess the effect of conditioned media (CM) from a triple-negative BC cell line (MDA-MB-231) on the metabolic profile of <i>Pseudomonas aeruginosa</i> (<i>P. aeruginosa</i>), an important breast resident Gram-negative bacteria that influence oncogenesis. Optical density and scanning electron microscopes were used to assess the impact of MDA-MB-231-CM (BC-CM) on <i>P. aeruginosa</i> growth and morphological changes, respectively. In addition, liquid chromatography-high-resolution mass spectrometry was used to identify metabolic changes in <i>P. aeruginosa</i> and their secretomes in response to the BC-CM. The BC-CM significantly suppressed the growth of <i>P. aeruginosa</i> in the log phase and induced concentration-dependent cytopathological changes in their cell walls. The metabolites of <i>P. aeruginosa</i> were dysregulated considerably depending on the time of exposure to the BC-CM. When treated with the BC-CM, <i>P. aeruginosa</i> induced the purine alkaloid spliceostatin (FR901464), a prominent antitumor metabolite. The BC-CM also promoted other <i>P. aeruginosa</i> metabolites such as amino acids, phosphoribosyl-AMP, 2-aminoacetophenone, pyochelin I, guanosine monophosphate, riboflavin, and terpenoids, which are capable of interfering with oncogenesis. Nine of the significantly identified metabolites from the 0-3 h comparison and four of those identified from the 0-6 h comparison have potential roles in influencing cancer cell behavior. Our findings demonstrate the ability of triple-negative BC-CM not only to alter the growth and morphology of <i>P. aeruginosa</i> but also to modulate their metabolic profile. A better understanding of the influence of BC on certain resident breast microbiomes, such as <i>P. aeruginosa,</i> may open a new therapeutic intervention opportunity for the treatment of cancer.