The bacterial spirochete Borrelia burgdorferi, the causative agent of Lyme Disease, can disseminate and colonize various tissues and organs, orchestrating severe clinical symptoms including arthritis, carditis, and neuroborreliosis. Previous research has demonstrated that breast cancer tissues could provide an ideal habitat for diverse populations of bacteria, including B. burgdorferi, which is associated with a poor prognosis. Recently, we demonstrated that infection with B. burgdorferi enhances the invasion and migration of triple-negative MDA-MB-231 cells which represent a type of breast tumor with more aggressive cancer traits. In this study, we hypothesized that infection by B. burgdorferi affects the expression of cancer-associated genes to effectuate breast cancer phenotypes. We applied the high-throughput technique of RNA-sequencing on B. burgdorferi-infected MDA-MB231 breast cancer and normal-like MCF10A cells to determine the most differentially expressed genes (DEG) upon infection. Overall, 142 DEGs were identified between uninfected and infected samples in MDA-MB-231 while 95 DEGs were found in MCF10A cells. A major trend of the upregulation of C-X-C and C-C motif chemokine family members as well as genes and pathways was associated with infection, inflammation, and cancer. These genes could serve as potential biomarkers for pathogen-related tumorigenesis and cancer progression which could lead to new therapeutic opportunities.  Kulcsszavak: Lyme disease, breast cancer, DEGs, TNBC, KEGG, REACTOME