J. Parker et al., PROSTAGLANDIN-H SYNTHASE EXPRESSION IS VARIABLE IN HUMAN COLORECTAL ADENOCARCINOMA CELL-LINES, Experimental cell research, 236(1), 1997, pp. 321-329
The expression of prostaglandin H synthases can be induced by many sti
muli and is likely to be important in control of the cell cycle, The a
nalysis of prostaglandin H synthase-1 and -2 expression in colon adeno
carcinoma cell lines is a useful model system for studying the functio
n of the prostaglandin H synthases, especially with regard to prolifer
ation and adhesion, Prostaglandin H synthase-1 protein is not found in
any of eight human colon adenocarcinoma cell lines. Expression of pro
staglandin H synthase-2 is variable for the eight cell lines: three co
nstitutively expressed active protein, four did not express this gene
at all, and one had mRNA but no active protein. Thus, five colorectal
adenocarcinoma cell lines exhibit ''null'' expression of prostaglandin
synthase-2. The three cell lines with constitutive expression of pros
taglandin H synthase-2 produce PGE(2). Prostaglandin E-2 production co
uld be inhibited by aspirin and NS398 without inhibiting proliferation
, while direct addition of prostaglandin E-2 inhibits proliferation. A
dhesion to collagen IV and fibronectin was stronger in those cell line
s that expressed prostaglandin H synthase-2. The constitutive expressi
on of prostaglandin H synthase-2 is associated with increased adhesion
to extracellular matrix components and a potential inhibition of prol
iferation through the production of prostaglandin E-2. The absence of
PGH synthase-2 expression in some cell lines may result from the origi
nal tumor's need to inactivate these associated functions. Our evidenc
e suggests that PGH synthase-2 is a possible candidate for a tumor sup
pressor gene at 1q23-qter. (C) 1997 Academic Press.