Although many clinical studies have found a correlation of SPARC expression with malignant progression and patient survival, the mechanisms for SPARC function in tumorigenesis and metastasis remain elusive. The activity of SPARC is context-and cell-type-dependent, which is highlighted by the fact that SPARC has shown seemingly contradictory effects on tumor progression in both clinical correlative studies and in animal models. The capacity of SPARC to dictate tumorigenic phenotype has been attributed to its effects on the bioavailability and signaling of integrins and growth factors/chemokines. These molecular pathways contribute to many physiological events affecting malignant progression, including extracellular matrix remodeling, angiogenesis, immune modulation and metastasis. Given that SPARC is credited with such varied activities, this review presents a comprehensive account of the divergent effects of SPARC in human cancers and mouse models, as well as a description of the potential mechanisms by which SPARC mediates these effects. We aim to provide insight into how a matricellular protein such as SPARC might generate paradoxical, yet relevant, tumor outcomes in order to unify an apparently incongruent collection of scientific literature.
To our knowledge this is the first study to provide detailed comparisons of acute transfusion reactions to all blood products between pediatric and adult populations at a single institution and supported by a single transfusion service and culture. Collectively these data provide insight into pediatric transfusion reactions and demonstrate a general increase in the incidence of transfusion reactions within the pediatric compared to adult population.
Pancreatic cancer is the fourth leading cause of cancer-related death in the USA and little improvement has been seen over the last 20 years in the 5-year survival rate, which remains at 5% (Surveillance, Epidemiology, and End Results, SEER, http://seer.cancer.gov). Historically, studies have focused on cell-autonomous behavior or the molecular biology of cancer cells. However, focus is shifting to the interaction of cancer cells with their microenvironment. In particular, desmoplasia (or stromal response) is prominent in pancreatic adenocarcinoma (Korc, 2007). Crosstalk between malignant epithelial cells and the stromal compartment can promote extracellular matrix (ECM) remodeling, angiogenesis, immune cell recruitment and metastasis (Desmouliere et al
The dissemination of prostate cancer to bone is a common, incurable aspect of advanced disease. Prevention and treatment of this terminal phase of prostate cancer requires improved molecular understanding of the process as well as markers indicative of molecular progression. Through biochemical analyses and loss-of-function in vivo studies we demonstrate that the cell adhesion molecule ALCAM is actively shed from metastatic prostate cancer cells by the sheddase ADAM17 in response to TGFβ. Not only is this post-translational modification of ALCAM a marker of prostate cancer progression, the molecule is also required for effective metastasis to bone. Biochemical analysis of prostate cancer cell lines reveal that ALCAM expression and shedding is elevated in response to TGFβ signaling. Both in vitro and in vivo shedding is mediated by ADAM17. Longitudinal analysis of circulating ALCAM in tumor-bearing mice revealed that shedding of tumor, but not host-derived ALCAM is elevated during growth of the cancer. Gene-specific knockdown of ALCAM in bone-metastatic PC3 cells greatly diminished both skeletal dissemination and tumor growth in bone. The reduced growth of ALCAM knockdown cells corresponded to an increase in apoptosis (Caspase-3) and decreased proliferation (Ki-67). Together these data demonstrate that the ALCAM is both a functional regulator as well as marker of prostate cancer progression.
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