Regulation of stromal cell cyclooxygenase-2 in the Apc Min/+ mouse model of intestinal tumorigenesis

Abstract

Cyclooxygenase-2 (Cox-2) is expressed predominantly by stromal cells in intestinal adenomas from the Apc(Min/+) mouse model of familial adenomatous polyposis. We investigated the mechanistic basis of stromal cell Cox-2 expression in Apc(Min/+) mouse adenomas, as well as Cox-2 expression and activity in histologically normal (HN) Apc(Min/+) mouse intestine, in order to gain further insights into regulation of Cox-2 as a potential chemoprevention target. Upregulation of Cox-2 in intestinal tumours is not an intrinsic feature of Apc(Min/+) macrophages as bone marrow-derived Apc(Min/+) macrophages did not exhibit an abnormality in Cox-2 expression or activity. Intestinal permeability to lactulose or mannitol was similar in Apc(Min/+) mice and wild-type littermates, implying that macrophage activation by luminal antigen is unlikely to explain stromal cell Cox-2 induction. Moreover, stromal cells exhibited differential expression of Cox-2 and inducible nitric oxide synthase, suggesting 'alternative' (M2) rather than 'classical' (M1) macrophage activation. Flow cytometric sorting of isolated stromal mononuclear cells (SMNCs), on the basis of M-lysozyme and specific macrophage marker expression, demonstrated that macrophages, neutrophils and non-myelomonocytic cells all contributed to lamina propria prostaglandin (PG) E(2) synthesis. However, the majority of PGE(2) synthesis by macrophages was via a Cox-2-dependent pathway compared with predominant Cox-1-derived PGE(2) production by non-myelomonocytic cells. SMNCs from HN Apc(Min/+) intestinal mucosa exhibited similar levels of Cox-2 mRNA and protein, but produced more Cox-2-derived PGE(2) than wild-type cells at 70 days of age. There was an age-dependent decline in PGE(2) synthesis by Apc(Min/+) SMNCs, despite tumour progression. These data suggest that other Cox-2-independent factors also control PGE(2) levels during Apc(Min/+) mouse intestinal tumorigenesis. Regulation of macrophage Cox-2 expression and other steps in PGE(2) synthesis (e.g. PGE synthase) are valid targets for novel chemoprevention strategies that could minimize or avoid systemic COX-2 inhibition.

Peripheral Administration of Morphine Attenuates Postincisional Pain by Regulating Macrophage Polarization through COX-2-Dependent Pathway

“…In response to peripheral inflammatory challenges by the administration of carrageenan and CFA, mice lacking the ATP-gated P2X4 channel did not elicit pain hypersensitivity and lacked the COX-dependent release of PGE2 [25], suggesting that COX-dependent release of PGE2 from macrophages is essential for the development of inflammatory pain. Conversely, previous reports have demonstrated that PGE2 promoted the differentiation of macrophages to the anti-inflammatory M2 phenotype [33,34]. PGE2 release was enhanced from peritoneal macrophages isolated from morphine-dependent rats [27].…”

Suppression of Tumorigenesis: Modulation of Inflammatory Cytokines by Oral Administration of Microencapsulated Probiotic Yogurt Formulation

“…However, as no single marker has been established yet as a practical cancer screening tool either in a general healthy population or in most high risk populations, a set of tests needs to be performed in order to draw conclusions. Cyclooxygenase (COX) is an enzyme which catalyzes the first step in the formation of prostaglandins (PGs), the conversion of arachidonic acid to PGH 2 , followed by the metabolism of PGH 2 to biologically active end-products, PGD 2 , PGE 2 , PGF α 2 , PGI 2 , or thromboxane A 2 (TxA 2 ) via specific synthases [15]. Two cyclooxygenase isoforms, COX-1 and COX-2, have been identified.…”

Paracrine cyclooxygenase-2 activity by macrophages drives colorectal adenoma progression in the Apc Min/+ mouse model of intestinal tumorigenesis

“…Cox-2 immunohistochemistry was also performed using a goat polyclonal anti-Cox-2 antibody (sc-1745, Santa Cruz Biotechnology, Inc., Dallas, TX), which was either indirectly labelled with biotinylated anti-goat immunoglobulin, for visualisation with a biotinylated rabbit anti-rat secondary antibody (DAKO UK Ltd., Ely, UK) and Vectorstain® ABC (Vector Laboratories, Inc.), or directly conjugated with AlexaFluor® 488 (Thermo Fisher Scientific) 57 . Tumour stromal cell Cox-2 immunoreactivity was scored 0–4 based on intensity and distribution in superficial areas of tumours below the luminal surface (0; no staining: 1; weak, patchy staining: 2; moderate staining with some continuity: 3, intense, continuous staining in a distinct area: 4; intense staining throughout the tumour).…”