Matrix metalloproteinase-1 expression in breast carcinoma: a marker for unfavorable prognosis

Matrix metalloproteinase-1 (MMP1) is a member of the matrix metalloproteinases family, and its aberrant expression is implicated in tumor invasion and metastasis. However, the relationship between MMP1 abnormal expression and clinical outcome in breast cancer patients remains to be elucidated. To address this issue, we conducted immunohistochemistry in breast cancer and adjacent normal tissues, and mined the transcriptional and survival data of MMP1 in breast cancer patients through Oncomine, Kaplan-Meier Plotter, bc-GenExMiner, COSMIC and cBioPortal databases. First, we found that both protein and mRNA levels of MMP1 expression were significantly higher in breast cancer tissues. Second, high MMP1 mRNA expression correlated with worse overall survival among grade II (HR = 1.75; p = 0.011), nodal-negative (HR = 2.00; p = 0.00028), ER-positive (HR = 1.61; p = 0.00027) and HER2-negative (HR = 3.17; p = 0.029) patients with breast cancer by using Kaplan-Meier plotter database. Third, the overexpression of MMP1 was associated with unfavorable survival results including overall survival (HR = 1.6; p = 1.6e-05), relapse free survival (HR = 1.78; p < 1e-16) and distant metastasis free survival (HR = 1.65; p = 5.3e-05) in patients with breast cancer. Taken together, the expression status of MMP1 is a significant prognostic indicator and a potential drug target for breast cancer.