The role of tumor cell-derived connective tissue growth factor (CTGF/CCN2) in pancreatic tumor growth.
Pancreatic cancer is highly aggressive and refractory to existing therapies. Connective tissue growth factor (CTGF/CCN2) is a fibrosis-related gene that is thought to play a role in pancreatic tumor progression. However, CCN2 can be expressed in a variety of cell types, and the contribution of CCN2 derived from either tumor cells or stromal cells as it affects the growth of pancreatic tumors is unknown. Using genetic inhibition of CCN2, we have discovered that CCN2 derived from tumor cells is a critical regulator of pancreatic tumor growth. Pancreatic tumor cells derived from CCN2 shRNA-expressing clones showed dramatically reduced growth in soft agar and when implanted s.c. We also observed a role for CCN2 in the growth of pancreatic tumors implanted orthotopically, with tumor volume measurements obtained by positron emission tomography imaging. Mechanistically, CCN2 protects cells from hypoxia-mediated apoptosis, providing an in vivo selection for tumor cells that express high levels of CCN2. We found that CCN2 expression and secretion was increased in hypoxic pancreatic tumor cells in vitro, and we observed colocalization of CCN2 and hypoxia in pancreatic tumor xenografts and clinical pancreatic adenocarcinomas. Furthermore, we found increased CCN2 staining in clinical pancreatic tumor tissue relative to stromal cells surrounding the tumor, supporting our assertion that tumor cell-derived CCN2 is important for pancreatic tumor growth. Taken together, these data improve our understanding of the mechanisms responsible for pancreatic tumor growth and progression, and also indicate that CCN2 produced by tumor cells represents a viable therapeutic target for the treatment of pancreatic cancer.
Bennewith
Kevin L
KL
Department of Radiation Oncology, Stanford University School of Medicine, Stanford, California, USA.
Huang
Xin
X
Ham
Christine M
CM
Graves
Edward E
EE
Erler
Janine T
JT
Kambham
Neeraja
N
Feazell
Jonathan
J
Yang
George P
GP
Koong
Albert
A
Giaccia
Amato J
AJ
D000230:Adenocarcinoma / Q000000981:diagnostic imaging / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D000818:Animals; D048708:Cell Growth Processes / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology; D055513:Connective Tissue Growth Factor / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D019788:Fluorodeoxyglucose F18 / Q000493:pharmacokinetics; D006801:Humans; D008297:Male; D051379:Mice; D008819:Mice, Nude; D010190:Pancreatic Neoplasms / Q000000981:diagnostic imaging / Q000235:genetics / Q000378:metabolism* / Q000473:pathology; D049268:Positron-Emission Tomography; D034741:RNA, Small Interfering / Q000235:genetics; D019275:Radiopharmaceuticals / Q000493:pharmacokinetics; D014162:Transfection; D014183:Transplantation, Heterologous
C526317:CCN2 protein, human; D034741:RNA, Small Interfering; D019275:Radiopharmaceuticals; D019788:Fluorodeoxyglucose F18; D055513:Connective Tissue Growth Factor