Fibroblast activation protein-α-expressing fibroblasts promote the progression of pancreatic ductal adenocarcinoma.
BACKGROUND
Pancreatic ductal adenocarcinoma (PDAC) is characterized by an extensive desmoplastic stromal response. Fibroblast activation protein-α (FAP) is best known for its presence in stromal cancer-associated fibroblasts (CAFs). Our aim was to assess whether FAP expression was associated with the prognosis of patients with PDAC and to investigate how FAP expressing CAFs contribute to the progression of PDAC.


METHODS
FAP expression was immunohistochemically assessed in 48 PDAC specimens. We also generated a fibroblastic cell line stably expressing FAP, and examined the effect of FAP-expressing fibroblasts on invasiveness and the cell cycle in MiaPaCa-2 cells (a pancreatic cancer cell line).


RESULTS
Stromal FAP expression was detected in 98% (47/48) of the specimens of PDAC, with the intensity being weak in 16, moderate in 19, and strong in 12 specimens, but was not detected in the 3 control noncancerous pancreatic specimens. Patients with moderate or strong FAP expression had significantly lower cumulative survival rates than those with negative or weak FAP expression (mean survival time; 352 vs. 497 days, P = 0.006). Multivariate analysis identified moderate to strong expression of FAP as one of the factors associated with the prognosis in patients with PDAC. The intensity of stromal FAP expression was also positively correlated to the histological differentiation of PDAC (P < 0.05). FAP-expressing fibroblasts promoted the invasiveness of MiaPaCa-2 cells more intensively than fibroblasts not expressing FAP. Coculture with FAP-expressing fibroblasts significantly activated cell cycle shift in MiaPaCa-2 cells compared to coculture with fibroblasts not expressing FAP. Furthermore, coculture with FAP expressing fibroblasts inactivated retinoblastoma (Rb) protein, an inhibitor of cell cycle progression, in MiaPaCa-2 cells by promoting phosphorylation of Rb.


CONCLUSIONS
The present in vitro results and the association of FAP expression with clinical outcomes provide us with a better understanding of the effect of FAP-expressing CAFs on the progression of PDAC.
Department of Hepatology and Pancreatology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan. oneworld_traveller@yahoo.co.jp.
Tomoya
T
Kawase
Department of Molecular Genetics, Kawasaki Medical School, Kurashiki, Japan. yumikoy@med.kawasaki-m.ac.jp.
Yumiko
Y
Yasui
Department of Hepatology and Pancreatology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan. 018ep@med.kawasaki-m.ac.jp.
Sohji
S
Nishina
Department of Hepatology and Pancreatology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan. yuich_h777@med.kawasaki-m.ac.jp.
Yuichi
Y
Hara
Department of Molecular Genetics, Kawasaki Medical School, Kurashiki, Japan. yanatori@med.kawasaki-m.ac.jp.
Izumi
I
Yanatori
Department of Hepatology and Pancreatology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan. tomiyama@med.kawasaki-m.ac.jp.
Yasuyuki
Y
Tomiyama
Department of Hepatology and Pancreatology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan. makazi777@med.kawasaki-m.ac.jp.
Yoshihiro
Y
Nakashima
Department of Hepatology and Pancreatology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan. kojiyos@med.kawasaki-m.ac.jp.
Koji
K
Yoshida
Department of Molecular Genetics, Kawasaki Medical School, Kurashiki, Japan. kishi@med.kawasaki-m.ac.jp.
Fumio
F
Kishi
Department of Digestive Surgery, Kawasaki Medical School, Kurashiki, Japan. mnaka@surg1.med.kyushu-u.ac.jp.|Department of Surgery and Oncology, Graduate School of Medical Sciences Kyusyu University, Fukuoka, Japan. mnaka@surg1.med.kyushu-u.ac.jp.
Masafumi
M
Nakamura
Department of Hepatology and Pancreatology, Kawasaki Medical School, 577 Matsushima, Kurashiki, Okayama, 701-0192, Japan. khino@med.kawasaki-m.ac.jp.
Keisuke
K
Hino
D000368:Aged; D021441:Carcinoma, Pancreatic Ductal / Q000737:chemistry / Q000473:pathology*; D059447:Cell Cycle Checkpoints; D045744:Cell Line, Tumor; D018920:Coculture Techniques; D018450:Disease Progression; D010450:Endopeptidases; D005260:Female; D005347:Fibroblasts / Q000378:metabolism*; D018093:Gelatinases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008297:Male; D008565:Membrane Proteins / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D008875:Middle Aged; D009361:Neoplasm Invasiveness; D010179:Pancreas / Q000737:chemistry; D010190:Pancreatic Neoplasms / Q000737:chemistry / Q000473:pathology*; D010766:Phosphorylation; D011379:Prognosis; D016160:Retinoblastoma Protein / Q000378:metabolism; D012697:Serine Endopeptidases / Q000032:analysis / Q000235:genetics / Q000378:metabolism*; D015996:Survival Rate; D000099167:Fibroblast Activation Protein Alpha
D010450:Endopeptidases; D018093:Gelatinases; D008565:Membrane Proteins; D016160:Retinoblastoma Protein; D012697:Serine Endopeptidases; D000099167:Fibroblast Activation Protein Alpha