RESUMO
BACKGROUND: Triple-negative breast cancer (TNBC) is the most aggressive subtype of breast cancer with a high probability of metastasis and a lack of specific targets and targeted therapeutics. Previously, we have reported that COL8A1, which is highly expressed in the mesenchymal stem-like (MSL) subtype of TNBC, facilitates TNBC growth via FAK/Src activation. Furthermore, we have found that COL8A1 enhances the invasion and metastasis of MDA-MB-231 cells, classified into MSL. However, the mechanism of invasion and metastasis by COL8A1 remains unclear. Here, we investigated the biological function of COL8A1 on the invasion and metastasis of MDA-MB-231 cells. METHODS: The invasion and metastasis of MDA-MB-231 cells were evaluated using three-dimensional (3D) culture methods and xenograft mouse models. DNA microarray analysis examined the gene expression in COL8A1-overexpressing MDA-MB-231 cells and control cells. Gene expression was verified using RT-qPCR. RESULTS: COL8A1-deficient cells showed little or no metastasis, whereas forced expression of COL8A1 in MDA-MB-231 cells, the MSL subtype of TNBC cell lines, significantly promoted distant metastasis after tumor resection. As with in vivo, 3D invasion assay revealed that COL8A1 increased the invasion capacity of MDA-MB-231 and Hs578T cells, classified into the MSL subtype of TNBC. DNA microarray analysis for COL8A1-overexpressing cells indicated that COL8A1 induces interleukin 1B (IL1B) and matrix metalloproteinase-1 (MMP1) expression, both of which are correlated with COL8A1 expression in the mesenchymal subtypes of TNBC, and the Kaplan-Meier plotter provided evidence that the prognosis in the MSL subtype was strongly associated with both gene expressions and COL8A1 expression. Pharmacological inhibitor treatment showed that COL8A1 regulated IL1B and MMP1 expression through a different pathway. Moreover, the knockdown of each gene expression reduced the invasion capacity of COL8A1-overexpressing MDA-MB-231 and Hs578T cells. CONCLUSION: Our findings indicate that COL8A1-induced IL1B and MMP1 enhanced the invasion and metastasis of the MSL subtype of TNBC. Considering our previous findings that COL8A1 promotes tumor growth, COL8A1 may be a prognostic and practical therapeutic target in TNBC.
