ABSTRACT
Overexpression of leucine aminopeptidase 3 (LAP3) is involved in proliferation, migration, and invasion of several tumor cells and plays a crucial role in tumor metastasis. However, the related mechanism remains unknown. In this study, we used MDA-MB-231 and MCF7 breast cancer cell lines to explore the role of LAP3 in the regulation of cancer cell migration and invasion by employing the natural LAP3 inhibitor bestatin and a lentivirus vector that overexpresses or knocks down LAP3. Bestatin inhibited tumor cell migration and invasion in a dose-dependent manner. Western blot assay showed that bestatin and knockdown of LAP3 upregulated phosphorylation of Hsp27 and downregulated expression of fascin. Phosphorylation of Akt and expression of matrix metalloproteinase-2/9 can also be downregulated. LAP3 overexpression showed the opposite results. Immunohistochemistry analysis was conducted to detect expression levels of LAP3 in breast cancer tissues. High LAP3 expression was correlated with the grade of malignancy. Findings of this study uncovered the molecular mechanism of LAP3 on breast cancer metastasis and indicated that LAP3 may act as a potential antimetastasis therapeutic target.
Subject(s)
Breast Neoplasms/metabolism , Carrier Proteins/blood , Cell Movement , Gene Expression Regulation, Neoplastic , Leucyl Aminopeptidase/metabolism , Matrix Metalloproteinase 2/biosynthesis , Matrix Metalloproteinase 9/biosynthesis , Microfilament Proteins/blood , Neoplasm Proteins/metabolism , Up-Regulation , Breast Neoplasms/genetics , Breast Neoplasms/pathology , Carrier Proteins/genetics , Female , Humans , Leucyl Aminopeptidase/genetics , MCF-7 Cells , Matrix Metalloproteinase 2/genetics , Matrix Metalloproteinase 9/genetics , Microfilament Proteins/genetics , Neoplasm Invasiveness , Neoplasm Proteins/geneticsABSTRACT
Cancer stem cells (CSCs) are responsible for chemoresistance, tumor recurrence and metastasis. Reportedly, aminopeptidase N (APN, also known as CD13) is a marker for semi-quiescent CSCs and a therapeutic target in human liver CSCs. In the present study, the effect of BC-02, a compound obtained by conjugating a CD13 inhibitor bestatin and fluorouracil (5-FU), was investigated toward liver CSCs. Tumor spheres formed in serum-free culture conditions have been successfully used to enrich CSCs. In this study, the sphere cells were shown to have several characteristics of CSCs, including drug resistance, high tumorigenicity, epithelial-mesenchymal transition (EMT) phenotype, lower reactive oxygen species (ROS) levels, greater colony-forming efficiency and increased proliferation capacity in vitro. Furthermore, BC-02 effectively suppressed self-renewal and malignant proliferation of CSCs compared with 5-FU, bestatin, and even the combination of 5-FU and bestatin. In addition, cell proliferation was effectively suppressed when exposed to 5-FU plus CD13-neutralizing antibody (CD13 Ab) compared with 5-FU alone. BC-02 can effectively inhibit the activity of CD13. Results demonstrated that CD13 inhibitor BC-02 impaired the properties of liver CSCs by targeting CD13 and upregulating the intracellular ROS and ROS-induced DNA damage. BC-02 might be a potential therapeutic agent for eradicating the liver CSCs and overcoming chemoresistance in liver cancer.
