15-Hydroxyprostaglandin dehydrogenase suppresses K-RasV12-dependent tumor formation in Nu/Nu mice.
Oncogenic Ras mutations are early genetic events in colorectal cancer that induce cyclooxygenase (COX)-2 expression and prostaglandin E(2) (PGE(2)) biosynthesis. PGE(2), a downstream product of COX-2, promotes cancer progression by modulating proliferation, apoptosis and angiogenesis. 15-hydroxyprostaglandin dehydrogenase (PGDH) degrades PGE(2) and is down-regulated in colorectal cancer, suggesting that PGDH plays a role in regulating PGE(2) levels and that PGDH over-expression could attenuate Ras-mediated tumorigenesis. Lentiviral transduction was used to express GFP (18.GFP), K-Ras(V12) (18.K-Ras(V12)), PGDH (18.PGDH) or both K-Ras(V12) and PGDH (18.K-Ras(V12).PGDH) in nontumorigenic rat intestinal epithelial (IEC-18) cells. 18.K-Ras(V12) cells exhibited increased phosphorylation of MAP kinases and CREB, proliferation rates, COX-2 and microsomal prostaglandin E synthase (mPGES)-1 expression and PGE(2) and PGI(2) levels. 18.PGDH and 18.K-Ras(V12).PGDH cells had 10(4)-fold increases in PGDH activity with decreased PGE(2) and PGI(2) levels, COX-2 and mPGES-1 expression and proliferation rates. 18.GFP, 18.PGDH, and 18.K-Ras(V12).PGDH cells were unable to grow in soft agar media whereas 18.K-Ras(V12) cells exhibited anchorage-independent cell growth. Xenografts of implanted 18.K-Ras(V12) cells in nu/nu mice produced rapid (2 wk) tumors with uniform antibody staining for COX-2 and mPGES-1 throughout the tumor and elevated PGE(2) levels. Xenografts of 18.K-Ras(V12).PGDH cells exhibited delayed (8 wk) tumor formation with negligible COX-2 and mPGES-1 expression and significantly decreased PGE(2) levels. 18.K-Ras(V12).PGDH tumors had decreased staining of the proliferative marker, Ki-67, and a significant increase in apoptosis in the central region of the tumor. Based on these data, we conclude that PGDH expression suppresses K-Ras(V12)-mediated tumorigenesis in intestinal epithelial cells.
Pham
Hung
H
Department of Medicine, Division of Digestive Diseases, University of California, Los Angeles, California, USA.
Eibl
Guido
G
Vincenti
Romina
R
Chong
Benny
B
Tai
Hsin-Hsiung
HH
Slice
Lee W
LW
D000818:Animals; D001483:Base Sequence; D002455:Cell Division; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D017931:DNA Primers; D011905:Genes, ras; D006911:Hydroxyprostaglandin Dehydrogenases / Q000378:metabolism*; D007150:Immunohistochemistry; D020287:In Situ Nick-End Labeling; D051379:Mice; D008819:Mice, Nude; D020928:Mitogen-Activated Protein Kinases / Q000378:metabolism; D009374:Neoplasms, Experimental / Q000201:enzymology / Q000378:metabolism / Q000473:pathology / Q000517:prevention & control*; D010766:Phosphorylation; D011453:Prostaglandins / Q000378:metabolism; D051381:Rats; D020133:Reverse Transcriptase Polymerase Chain Reaction
D017362:Cyclic AMP Response Element-Binding Protein; D017931:DNA Primers; D011453:Prostaglandins; D006911:Hydroxyprostaglandin Dehydrogenases; C035859:15-hydroxyprostaglandin dehydrogenase; D020928:Mitogen-Activated Protein Kinases