SPARC Regulates Transforming Growth Factor Beta Induced (TGFBI) Extracellular Matrix Deposition and Paclitaxel Response in Ovarian Cancer Cells.
TGFBI has been shown to sensitize ovarian cancer cells to the cytotoxic effects of paclitaxel via an integrin receptor-mediated mechanism that modulates microtubule stability. Herein, we determine that TGFBI localizes within organized fibrillar structures in mesothelial-derived ECM. We determined that suppression of SPARC expression by shRNA decreased the deposition of TGFBI in mesothelial-derived ECM, without affecting its overall protein expression or secretion. Conversely, overexpression of SPARC increased TGFBI deposition. A SPARC-YFP fusion construct expressed by the Met5a cell line co-localized with TGFBI in the cell-derived ECM. Interestingly, in vitro produced SPARC was capable of precipitating TGFBI from cell lysates dependent on an intact SPARC carboxy-terminus with in vitro binding assays verifying a direct interaction. The last 37 amino acids of SPARC were shown to be required for the TGFBI interaction while expression of a SPARC-YFP construct lacking this region (aa 1-256) did not interact and co-localize with TGFBI in the ECM. Furthermore, ovarian cancer cells have a reduced motility and decreased response to the chemotherapeutic agent paclitaxel when plated on ECM derived from mesothelial cells lacking SPARC compared to control mesothelial-derived ECM. In conclusion, SPARC regulates the fibrillar ECM deposition of TGFBI through a novel interaction, subsequently influencing cancer cell behavior.
Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, United Kingdom.
David A
http://orcid.org/0000-0002-5169-0561
DA
Tumbarello
University of St Andrews, School of Medicine, MBSB, North Haugh, St Andrews, United Kingdom.
Melissa R
MR
Andrews
Cancer Research UK Cambridge Institute, University of Cambridge, Robinson Way, Cambridge, United Kingdom.
James D
JD
Brenton
D000972:Antineoplastic Agents, Phytogenic / Q000494:pharmacology*; D045744:Cell Line, Tumor; D002465:Cell Movement / Q000187:drug effects; D004847:Epithelial Cells / Q000378:metabolism; D005109:Extracellular Matrix / Q000187:drug effects / Q000378:metabolism; D016326:Extracellular Matrix Proteins / Q000378:metabolism*; D005260:Female; D005353:Fibronectins / Q000378:metabolism; D006801:Humans; D015676:Osteonectin / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D010051:Ovarian Neoplasms / Q000188:drug therapy* / Q000378:metabolism*; D017239:Paclitaxel / Q000494:pharmacology*; D034741:RNA, Small Interfering / Q000235:genetics; D011993:Recombinant Fusion Proteins / Q000235:genetics / Q000378:metabolism; D016212:Transforming Growth Factor beta / Q000378:metabolism*; D000099222:betaIG-H3 Protein
D000972:Antineoplastic Agents, Phytogenic; D016326:Extracellular Matrix Proteins; D005353:Fibronectins; D015676:Osteonectin; D017239:Paclitaxel; D034741:RNA, Small Interfering; D011993:Recombinant Fusion Proteins; D016212:Transforming Growth Factor beta; D000099222:betaIG-H3 Protein; C577241:SPARC protein, human