Association between taurine transporter SLC6A6 and breast cancer development and prognosis: a Mendelian randomization...

Breast cancer is the most common malignancy among women worldwide, with early screening and diagnosis being crucial for improving patient prognosis. Taurine, as an important metabolite, shows significant changes during breast cancer development, while the taurine transporter SLC6A6 may play a key role in breast cancer progression.

This study systematically investigated the relationship between taurine level changes and breast cancer development through cell experiments, animal models, and clinical sample analysis. ¹H NMR and HPLC techniques were used to measure taurine levels in different breast cancer cell lines, MMTV-PyMT transgenic mouse models, and clinical patient serum. Molecular docking, functional analysis, and immune infiltration analysis were employed to explore the mechanism of SLC6A6. Mendelian randomization (MR) analysis was used to evaluate the causal relationship between immune cell subsets and breast cancer risk.

Intracellular taurine levels were elevated, while extracellular taurine levels decreased in breast cancer cells, correlating with malignancy degree. Serum taurine levels in MMTV-PyMT mice and clinical patients decreased continuously with disease progression, with significant changes detectable at the carcinoma in situ stage. Serum taurine demonstrated good diagnostic value as an early breast cancer marker, with ROC analysis showing an AUC of 0.939, sensitivity of 0.900, and specificity of 1.000 in distinguishing benign tumors from carcinoma in situ. SLC6A6 was highly expressed in breast cancer tissues and significantly associated with poor patient prognosis. Mendelian randomization analysis revealed potential causal relationships between specific immune cell subsets (such as naive B cells, TCRgd cells) and breast cancer risk, while CD14⁺CD16^- monocytes showed a protective effect. Single-cell sequencing analysis indicated that SLC6A6 is primarily enriched in endothelial cells and fibroblasts within tumor tissues.

Taurine metabolic reprogramming can serve as a potential marker for early breast cancer diagnosis. SLC6A6 participates in breast cancer progression by regulating taurine levels and influencing immune infiltration, representing an independent predictor of breast cancer prognosis and a potential therapeutic target.