Decorin protein core affects the global gene expression profile of the tumor microenvironment in a triple-negative orthotopic breast carcinoma xenograft model

Decorin, a member of the small leucine-rich proteoglycan gene family, exists and functions wholly within the tumor microenvironment to suppress tumorigenesis by directly targeting and antagonizing multiple receptor tyrosine kinases, such as the EGFR and Met. This leads to potent and sustained signal attenuation, growth arrest, and angiostasis. We thus sought to evaluate the tumoricidal benefits of systemic decorin on a triple-negative orthotopic breast carcinoma xenograft model. To this end, we employed a novel high-density mixed expression array capable of differentiating and simultaneously measuring gene signatures of both Mus musculus (stromal) and Homo sapiens (epithelial) tissue origins. We found that decorin protein core modulated the differential expression of 374 genes within the stromal compartment of the tumor xenograft. Further, our top gene ontology classes strongly suggests an unexpected and preferential role for decorin protein core to inhibit genes necessary for immunomodulatory responses while simultaneously inducing expression of those possessing cellular adhesion and tumor suppressive gene properties. Rigorous verification of the top scoring candidates led to the discovery of three genes heretofore unlinked to malignant breast cancer that were reproducibly found to be induced in several models of tumor stroma. Collectively, our data provide highly novel and unexpected stromal gene signatures as a direct function of systemic administration of decorin protein core and reveals a fundamental basis of action for decorin to modulate the tumor stroma as a biological mechanism for the ascribed anti-tumorigenic properties

Scleroderma-like properties of skin from caveolin-1-deficient mice: Implications for new treatment strategies in patients with fibrosis and systemic sclerosis

Caveolin-1 (Cav-1), the principal structural component of caveolae, participates in the pathogenesis of several fibrotic diseases, including systemic sclerosis (SSc). Interestingly, affected skin and lung samples from patients with SSc show reduced levels of Cav-1, as compared to normal skin. In addition, restoration of Cav-1 function in skin fibroblasts from SSc patients reversed their pro-fibrotic phenotype. Here, we further investigated whether Cav-1 mice are a useful preclinical model for studying the pathogenesis of SSc. For this purpose, we performed quantitative transmission electron microscopy, as well as biochemical, biomechanical, and immuno-histochemical analysis, of the skin from Cav-1(-/-) null mice. Using these complementary approaches, we now show that skin from Cav-1 null mice exhibits many of the same characteristics as SSc skin from patients. These changes include a decrease in collagen fiber diameter, increased maximum stress (a measure tensile strength) and modulus (a measure of stiffness), as well as mononuclear cell infiltration. Furthermore, an increase in autophagy/mitophagy was observed in the stromal cells of the dermis from Cav-1(-/-) mice. These findings suggest that changes in cellular energy metabolism (e.g., a shift towards aerobic glycolysis) in these stromal cells may provide a survival mechanism in this “hostile” or pro-inflammatory microenvironment. Taken together, our results demonstrate that Cav-1(-/-) mice are a valuable new pre-clinical model for studying scleroderma. Most importantly, our results suggest that inhibition of autophagy and/or aerobic glycolysis may represent a new promising therapeutic strategy for halting fibrosis in SSc patients. Finally, Cav-1(-/-) mice are also a pre-clinical model for a “lethal” tumor microenvironment, possibly explaining the link between fibrosis, tumor progression and cancer metastasis

Expression array analysis of several ductal breast carcinoma microarray datasets.

<p>Statistical significance is reported as a summary statistic calculated utilizing the ONCOMINE gene expression tool <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045559#pone.0045559-Rhodes1" target="_blank">[90]</a>. As shown in the report by Karnoub <i>et al. </i><a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045559#pone.0045559-Karnoub1" target="_blank">[91]</a> (<i>left panel</i>) there was a 3.1-fold reduction of PEG3 mRNA within invasive ductal breast carcinoma (<i>P</i> = 3.64×10⁻⁶). Additionally, in the study by Richardson <i>et al</i>. <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0045559#pone.0045559-Richardson1" target="_blank">[92]</a> (<i>right panel</i>), PEG3 levels were found to be decreased by 5.6-fold in ductal breast carcinoma samples (<i>P</i> = 1.86×10⁻⁶).</p

Systemic administration of decorin protein core induces Peg3 and Bmp2k levels in MDA-231(GFP+) xenografts.

<p><b>A–B</b>: Immunofluorescence images of control and decorin-treated MDA-231(GFP+) tumor xenografts, reacted with anti-Peg3 (A) or anti-Bmp2k (B) antibodies. Mice bearing MDA-231(GFP+) tumor xenografts were treated with intraperitoneal injection of decorin protein core (10 mg/kg) every other day for 23 days. All the micrographs were taken using the same exposure and gain. Three-dimensional surface plots, on the right of each panel, were generated utilizing ImageJ software and represent Peg3 and Bmp2k expression which directly corresponds to the signal intensity obtained by the immunofluorescence. The scale bars for signal intensity are included on the right of each surface plot. Bar = 20 µm.</p