Circulating tumor cell heterogeneity and MMP9 expression in clinical correlation with breast cancer

Objectives This study aimed to investigate the association between the heterogeneity of circulating tumor cell (CTC) subtypes and the expression patterns of matrix metalloproteinase 9 (MMP9) with clinicopathological parameters in breast cancer patients. The distribution of CTC subtypes, MMP9 expression levels, and their influence on tumor progression. Methods A total of 303 breast cancer patients were enrolled in this study. The association between CTCs subtypes in peripheral blood, MMP9 expression and clinical or pathological data of patients were analyzed. Results The number of mesenchymal CTCs increased significantly with the number of lymph node metastases ( P < 0.05), and high MMP9 expression was positively correlated with lymph node involvement ( P < 0.05). The proportion of intermediate to high MMP9 expression was significantly higher in mixed CTCs compared to epithelial and mesenchymal CTCs ( P < 0.05). High MMP9 expression in tumor tissues was associated with increased CTCs production and induction of epithelial-mesenchymal transition (EMT) ( P < 0.05), as well as an elevated number of MMP9-positive CTCs ( P < 0.05). Conclusions These findings suggest that MMP9 is positively associated with CTCs production and EMT process, and MMP9 may contribute to tumor metastasis by promoting CTC shedding and EMT by degrading the extracellular matrix. We recommend compliance with the Mesh guidelines: https://www.ncbi.nlm.nih.gov/mesh/