Abstract
The correlation between the microbiota found in tumors and tumor development is being progressively understood, specifically regarding its involvement in the initiation and advancement of tumors. We examined a total of 102 samples, examining the microbial composition at the species level in each person unveiled significant variations in both the microbial makeup and tumor proportions among individuals, examining the fluctuating alterations in the microbial profile during breast cancer advancement and progression. The levels of expression for Pseudoalteromonas elyakovii were notably elevated in the tumor groups when compared to the para-cancer normal group, aligning with the results obtained from qRT-PCR analysis. The relationship between tumor immunity and microorganisms within the tumor was investigated using double immunofluorescence staining combined with SweAMI probe in situ hybridization and scRNA-seq, allowing for an in-depth analysis of intratumoral microorganisms. Experiments have demonstrated that the supernatant derived from P. elyakovii displayed a significant ability to promote tumor growth and stimulation. In summary, we describe the characteristics of the intratumoral microbiota and the tumor-promoting effects of P. elyakovii supernatant within a small dose range in ductal carcinoma of the breast and characterize the potential clinical application value of intratumoural microorganisms in the progression of cancer and immunotherapy. IMPORTANCE: Despite the existing studies, the specific microbial factors that influence the occurrence and progression of breast cancer still remain unclear. Researchers have clarified the distinctive microbial profile related to ductal carcinoma, a common histological type of breast cancer, in order to identify tumor-specific microbes and their roles in tumorigenesis. With the tumor microbiome as the focus, the enrichment of Pseudoalteromonas elyakovii features accelerates the disease progression in patients with ductal carcinoma of the breast. This study reveals the initial role relationship and innovative findings between Pseudoalteromonas elyakovii and ductal carcinoma in the breast.