Unconjugated
Reduced expression levels of caveolin‑1 (Cav‑1) in tumor stromal fibroblasts influences the occurrence and progression of tumors, particularly in breast cancer, but the relevant molecular mechanism is unclear. The present study aimed to clarify the potential mechanism underlying the promotion of tumor growth by reduced Cav‑1 expression levels, by investigating Cav‑1‑targeted molecules in fibroblasts and breast cancer cells. The expression of growth factors in the ESF fibroblast cell line transfected with Cav‑1 small interfering RNA (siRNA) was examined. The expression of apoptotic regulators in the BT474 breast cancer cell line that was co‑cultured with the fibroblasts, was also investigated. The transfection of Cav‑1‑targeting siRNA in ESF cells resulted in efficient and specific inhibition of Cav‑1 expression. The downregulation of Cav‑1 increased the expression and secretion of stromal cell‑derived factor‑1 (SDF‑1), epidermal growth factor (EGF) and fibroblast‑specific protein‑1 (FSP‑1) in ESF cells. This resulted in the accelerated proliferation of the breast cancer cells. Tumor protein 53‑induced glycolysis and apoptosis regulator (TIGAR) was upregulated in the BT474 cells under the condition of co‑culture with Cav‑1 siRNA fibroblasts, while levels of reactive oxygen species (ROS) were decreased, resulting in apoptosis inhibition in the breast cancer cells. These results demonstrated that the downregulation of Cav‑1 promoted the growth of breast cancer cells through increasing SDF‑1, EGF and FSP‑1 in tumor stromal fibroblasts, and TIGAR levels in breast cancer cells. To the best of our knowledge, the present study supports the hypothesis that Cav‑1 possesses tumor‑suppressor properties, with the mechanism of Cav‑1‑dependent signaling involving the regulation of SDF‑1, EGF, FSP‑1 and TIGAR.
Noninvasive diagnosis of atherosclerosis via single biomarkers has been attempted but remains elusive. However, a previous polymarker or pattern approach of urine polypeptides in humans reflected coronary artery disease with high accuracy. The aim of the current study is to use urine proteomics in ApoE(-/-) mice to discover proteins with pathophysiological roles in atherogenesis and to identify urinary polypeptide patterns reflecting early stages of atherosclerosis. Urine of ApoE(-/-) mice either on high fat diet (HFD) or chow diet was collected over 12 weeks; urine of wild type mice on HFD was used to exclude diet-related proteome changes. Capillary electrophoresis coupled to mass spectrometry (CE-MS) of samples identified 16 polypeptides specific for ApoE(-/-) mice on HFD. In a blinded test set, these polypeptides allowed identification of atherosclerosis at a sensitivity of 90% and specificity of 100%, as well as monitoring of disease progression. Sequencing of the discovered polypeptides identified fragments of α(1)-antitrypsin, epidermal growth factor (EGF), kidney androgen-regulated protein, and collagen. Using immunohistochemistry, α(1)-antitrypsin, EGF, and collagen type I were shown to be highly expressed in atherosclerotic plaques of ApoE(-/-) mice on HFD. Urinary excretion levels of collagen and α(1)-antitrypsin fragments also significantly correlated with intraplaque collagen and α(1)-antitrypsin content, mirroring plaque protein expression in the urine proteome. To provide further confirmation that the newly identified proteins are relevant in humans, the presence of collagen type I, α(1)-antitrypsin, and EGF was also confirmed in human atherosclerotic disease. Urine proteome analysis in mice exemplifies the potential of a novel multimarker approach for the noninvasive detection of atherosclerosis and monitoring of disease progression. Furthermore, this approach represents a novel discovery tool for the identification of proteins relevant in murine and human atherosclerosis and thus also defines potential novel therapeutic targets.
