Integrating scRNA-seq and spatial transcriptomics to explore the implication of G6PD on immune microenvironment in lymphatic metastasis of breast cancer

Breast cancer is among the most prevalent malignancies, with lymph node metastasis strongly linked to worse prognostic outcomes. Despite this, the mechanisms underlying the formation of an immunosuppressive microenvironment that drives lymph node metastasis remain poorly understood. By profiling 118,127 cells from eight patients with breast cancer alongside their metastatic axillary lymph nodes through single-cell sequencing and spatial transcriptomics, this study uncovered the activation of the pentose phosphate pathway during the metastatic process. The expression level of G6PD in breast cancer tumor tissues was significantly higher than that in adjacent tissues. Furthermore, high G6PD expression was associated with poorer prognosis. G6PD was more highly expressed in metastatic lymph nodes, which exhibited an immunosuppressive microenvironment induced by CD4 Treg cells, and the expression of G6PD was positively correlated with immune cell infiltration by Treg cells. Clinical evaluation further demonstrated a significant correlation among G6PD expression, lymph node metastasis, and malignancy. Additionally, clinical drug response data revealed that patients resistant to chemotherapy also had higher G6PD expression. These findings establish G6PD as a molecular marker for predicting the risk of lymph node metastasis and prognosis in breast cancer. This study discovered elevated expression of G6PD in breast cancer, as well as the formation of an immunosuppressive microenvironment mediated by Treg cells in breast cancer lymph node metastatic tissues, emphasizing the critical role of G6PD in promoting lymph node metastasis by driving Treg cell infiltration.