Increasing evidence suggests that intratumoral microorganisms and their metabolites can modulate cancer initiation and progression. However, the composition and functional role of intratumoral bacteria in canine mammary tumors (CMTs) remain unclear. In this study, we investigated the functional significance of tumor-derived Staphylococcus in CMTs, focusing on its effects on the proliferation and migration of CMT-U27 cells. 16S rRNA sequencing revealed reduced alpha diversity in CMT tissues, with Staphylococcus pseudintermedius identified as the most frequently isolated species. Functional assays, including CCK-8, wound healing, RT-qPCR, and Western blot analyses, demonstrated that intratumoral Staphylococcus pseudintermedius significantly enhanced cellular proliferation and migration. Mechanistically, Staphylococcus pseudintermedius significantly upregulated the expression of TLR2, as well as the phosphorylation levels of PI3K, Akt and P70S6K. The inhibition of TLR2 using C29 suppressed the mRNA expression of VEGF, MMP9, MMP2, and EGFR. Collectively, these findings indicate that intratumoral Staphylococcus pseudintermedius promotes the proliferation and migration of CMT-U27 cells through activation of the TLR2/PI3K/Akt pathway, highlighting a functional link between tumor-associated bacteria and cancer progression.
Luo et al. (Fri,) studied this question.