Measuring Exercise-Induced Secreted Protein Acidic and Rich in Cysteine Expression as a Molecular Tool to Optimize Personalized Medicine

The numerous exercise benefits for health as well as applications for diseases has lead to exercise being prescribed in many pathological conditions. Secreted protein acidic and rich in cysteine (SPARC) gene expression is stimulated by exercise and SPARC has been suggested as a molecular mediator of exercise. Therefore, we suggest using this property for personalized medicine. This can be achieved by prescribing the exercise with a pattern (duration, intensity, etc.) that corresponds to the optimum SPARC/Sparc expression. We expect this approach to optimize the exercise therapy in both the preventive and curative contexts. In the research field, measuring exercise -dependent expression of Sparc would represent a molecular tool to further optimize the selection of exercise animal models as well.

Secreted Protein Acidic and Rich in Cysteine as a Molecular Physiological and Pathological Biomarker

Secreted protein acidic and rich in cysteine (SPARC) is expressed in diverse tissues and plays roles in various biological functions and processes. Increased serum levels of SPARC or its gene overexpression have been reported following numerous physiological and pathological changes including injuries, exercise, regeneration, obesity, cancer, and inflammation. Such expression pattern interrelation between these biological changes and the SPARC expression/secretion points to it as a biomarker. This property could lead to a variety of potential applications ranging from mechanistic studies and animal model validation to the clinical and therapeutic evaluation of both disease prognosis and pharmacological agents.

SPARC in cancer-associated fibroblasts is an independent poor prognostic factor in non-metastatic triple-negative breast cancer and exhibits pro-tumor activity

Purpose: Triple-negative breast cancer (TNBC) is the most aggressive breast cancer subtype and lacks specific targeted therapeutics. The current mechanistic evidence from cell-based studies suggests that the matricellular protein SPARC has a tumor-promoting role in TNBC; however, data on the clinical relevance of SPARC expression/secretion by tumor and stromal cells in TNBC are limited. Experimental Design: This study analyzed the prognostic value of tumor and stromal cell SPARC expression in a large series of 148 patients with non-metastatic TNBC and long follow-up (median: 5.4 years). Fibrosis, tumor-associated macrophage (TAM) infiltration, tumor-infiltrating lymphocyte (TIL) density, PD-L1 and PD-1 expression were assessed. Tumor and stromal cell SPARC expression was studied by immunofluorescence, western blotting, and meta-analysis of published single-cell mRNA sequencing data. The biological role of fibroblast-secreted SPARC was analyzed using cell adhesion, wound healing, Transwell-based motility and invasion, and tumor spheroid assays. Results: SPARC expression was detected in cancer cells (42.4%), cancer-associated fibroblasts (CAFs) (88.1%), TAMs (77.1%), endothelial cells (75.2%), and TILs (9.8%). Recurrence-free survival was significantly lower in patients with SPARC-expressing CAFs. SPARC expression in CAFs was an independent prognostic factor in multivariate analysis. Tumor and stromal cell SPARC expression was observed in TNBC cytosols, patient-derived xenografts, and cell lines. SPARC was expressed by different CAF subsets, including myofibroblasts and inflammatory CAFs. Fibroblast-secreted SPARC inhibited TNBC cell adhesion and stimulated their migration and invasion. Conclusions: SPARC expression in CAFs is an independent predictor of recurrence-free survival in TNBC. Patients with SPARC-expressing CAFs could be eligible for anti-SPARC-targeted therapy.

USP22 Suppresses SPARC Expression in Acute Colitis and Inflammation-Associated Colorectal Cancer

As a member of the 11-gene “death-from-cancer” gene expression signature, ubiquitin-specific protease 22 (USP22) has been considered an oncogene in various human malignancies, including colorectal cancer (CRC). We recently identified an unexpected tumor-suppressive function of USP22 in CRC and detected intestinal inflammation after Usp22 deletion in mice. We aimed to investigate the function of USP22 in intestinal inflammation as well as inflammation-associated CRC. We evaluated the effects of a conditional, intestine-specific knockout of Usp22 during dextran sodium sulfate (DSS)-induced colitis and in a model for inflammation-associated CRC. Mice were analyzed phenotypically and histologically. Differentially regulated genes were identified in USP22-deficient human CRC cells and the occupancy of active histone markers was determined using chromatin immunoprecipitation. The knockout of Usp22 increased inflammation-associated symptoms after DSS treatment locally and systemically. In addition, Usp22 deletion resulted in increased inflammation-associated colorectal tumor growth. Mechanistically, USP22 depletion in human CRC cells induced a profound upregulation of secreted protein acidic and rich in cysteine (SPARC) by affecting H3K27ac and H2Bub1 occupancy on the SPARC gene. The induction of SPARC was confirmed in vivo in our intestinal Usp22-deficient mice. Together, our findings uncover that USP22 controls SPARC expression and inflammation intensity in colitis and CRC.

Fibronectin mediates activation of stromal fibroblasts by SPARC in endometrial cancer cells

Background Matricellular glycoprotein, SPARC is a secreted molecule, that mediates the interaction between cells and extracellular matrix. SPARC functions as a regulator of matrix organization and modulates cell behavior. In various kinds of cancer, strong SPARC expression was observed in stromal tissues as well as in cancer epithelial cells. The function of SPARC in cancer cells is somewhat controversial and its impact on peritumoral stromal cells remains to be resolved. Methods We investigated the effects of SPARC expression in endometrial cancer cells on the surrounding stromal fibroblasts using in vitro co-culture system. Changes in characteristics of fibroblasts were examined by analysis of fibroblast-specific markers and in vitro contraction assay. Results SPARC induced AKT phosphorylation and epithelial-to-mesenchymal transition, consistent with previous reports. Cancer-associated fibroblasts of endometrial cancer expressed higher levels of mesenchymal- and fibroblast-associated factors and had a stronger contraction ability. Unexpectedly, cancer-associated fibroblasts expressed comparable levels of SPARC compared with fibroblasts from normal endometrium. However, co-culture of normal fibroblasts with SPARC-expressing Ishikawa cells resulted in activation of the fibroblasts. Immunodepletion of SPARC did not affect the activation of fibroblasts. Conclusions Our data indicated that SPARC activated fibroblasts only in the presence of fibronectin, which was abundantly secreted from SPARC-expressing endometrial cancer cells. These results suggested that a SPARC-fibronectin-mediated activation of fibroblasts might be involved in enhanced mobility and invasion of cancer cells.

SPARC Production by Bone Marrow-Derived Cells Contributes to Myocardial Fibrosis in Pressure-Overload

In human heart failure and in murine hearts with left ventricular pressure overload (LVPO), increases in fibrosis are associated with increases in stiffness. Secreted Protein Acidic and Rich in Cysteine (SPARC) is necessary for both cardiac fibrosis and increases in myocardial stiffness in response to LVPO, however cellular sources of cardiac SPARC are incompletely defined. Irradiation and bone marrow transfer were undertaken to test the hypothesis that SPARC expression by bone marrow-derived cells is an important mediator of fibrosis in LVPO. In recipient SPARC-null mice transplanted with donor wild-type (WT) bone marrow and subjected to LVPO, levels of fibrosis similar to that of WT hearts were found despite the lack of SPARC expression by resident cells. In recipient WT mice with donor SPARC-null bone marrow, significantly less fibrosis versus that of WT was found despite the expression of SPARC by resident cells. Increases in myocardial stiffness followed a similar pattern to that of collagen deposition. Myocardial macrophages were significantly reduced in SPARC-null mice with LVPO versus that of WT hearts. Recipient SPARC-null mice transplanted with donor WT bone marrow exhibited an increase in cardiac macrophages versus that of SPARC-null LVPO and donor WT mice with recipient SPARC-null bone marrow. Expression of Vascular Cellular Adhesion Molecule (VCAM) was found to be in increased in all groups with LVPO with the exception of WT mice. In conclusion, SPARC expression by bone marrow-derived cells was critical for fibrotic deposition of collagen and influenced the expansion of myocardial macrophages in response to LVPO.