关键词:
Breast cancer
Lung and intrathoracic tumors
Cancer treatment
Metastasis
Gastric cancer
Fibroblasts
Extracellular matrix proteins
Gene expression
摘要:
Background Breast cancer is a leading malignancy affecting the female population worldwide. Most morbidity is caused by metastases that remain incurable to date. TGF-beta 1 has been identified as a key driving force behind metastatic breast cancer, with promising therapeutic implications. Methods and Findings Employing immunohistochemistry (IHC) analysis, we report, to our knowledge for the first time, that asporin is overexpressed in the stroma of most human breast cancers and is not expressed in normal breast tissue. In vitro, asporin is secreted by breast fibroblasts upon exposure to conditioned medium from some but not all human breast cancer cells. While hormone receptor (HR) positive cells cause strong asporin expression, triple-negative breast cancer (TNBC) cells suppress it. Further, our findings show that soluble IL-1 beta, secreted by TNBC cells, is responsible for inhibiting asporin in normal and cancer-associated fibroblasts. Using recombinant protein, as well as a synthetic peptide fragment, we demonstrate the ability of asporin to inhibit TGF-beta 1-mediated SMAD2 phosphorylation, epithelial to mesenchymal transition, and stemness in breast cancer cells. In two in vivo murine models of TNBC, we observed that tumors expressing asporin exhibit significantly reduced growth (2-fold;p = 0.01) and metastatic properties (3-fold;p = 0.045). A retrospective IHC study performed on human breast carcinoma (n = 180) demonstrates that asporin expression is lowest in TNBC and HER2+ tumors, while HR+ tumors have significantly higher asporin expression (4-fold;p = 0.001). Assessment of asporin expression and patient outcome (n = 60;10-y follow-up) shows that low protein levels in the primary breast lesion significantly delineate patients with bad outcome regardless of the tumor HR status (area under the curve = 0.87;95% CI 0.78-0.96;p = 0.0001). Survival analysis, based on gene expression (n = 375;25-y follow-up), confirmed that low asporin levels are associated with a