The omega‐3 polyunsaturated fatty acid eicosapentaenoic acid inhibits mouse MC‐26 colorectal cancer cell liver metastasis via inhibition of PGE₂‐dependent cell motility

Abstract

BACKGROUND AND PURPOSEThe omega-3 polyunsaturated fatty acid (PUFA) eicosapentaenoic acid (EPA) has antineoplastic activity at early stages of colorectal carcinogenesis, relevant to chemoprevention of colorectal cancer (CRC). We tested the hypothesis that EPA also has anti-CRC activity at later stages of colorectal carcinogenesis, relevant to treatment of metastatic CRC, via modulation of E-type PG synthesis. EXPERIMENTAL APPROACHA BALB/c mouse model, in which intrasplenic injection of syngeneic MC-26 mouse CRC cells leads to development of liver metastases, was used. Dietary EPA was administered in the free fatty acid (FFA) form for 2 weeks before and after ultrasoundguided intrasplenic injection of 1 ¥ 10 6 MC-26 cells (n = 16 each group). KEY RESULTSTreatment with 5% (w w -1 ) EPA-FFA was associated with a reduced MC-26 mouse CRC cell liver tumour burden compared with control animals (median liver weight 1.03 g vs. 1.62 g; P < 0.034). Administration of 5% EPA-FFA was also linked to a significant increase in tumour EPA incorporation and lower intratumoural PGE2 levels (with concomitant increased production of PGE3). Liver tumours from 5% EPA-FFA-treated mice demonstrated decreased 5-bromo-2-deoxyuridine-positive CRC cell proliferation and reduced phosphorylated ERK 1/2 expression at the invasive edge of tumours. A concentration-dependent reduction in MC-26 CRC cell Transwell® migration following EPA-FFA treatment (50-200 mM) in vitro was rescued by exogenous PGE2 (10 mM) and PGE1-alcohol (1 mM). CONCLUSIONS AND IMPLICATIONSEPA-FFA inhibits MC-26 CRC cell liver metastasis. EPA incorporation is associated with a 'PGE2 to PGE3 switch' in liver tumours. Inhibition of PGE2-EP4 receptor-dependent CRC cell motility probably contributes to the antineoplastic activity of EPA. AbbreviationsAA, arachidonic acid; BrdU, 5-bromo-2

Gα13/PDZ-RhoGEF/RhoA Signaling Is Essential for Gastrin-Releasing Peptide Receptor–Mediated Colon Cancer Cell Migration

“…Our findings are in line with other studies that have also reported the role of ROCK in regulating Cox-2 expression downstream of another GPCR, proteinaseactivated receptor-2 (Hirota et al, 2012). Current evidence indicates that Cox-2-PGE 2 signaling stimulates colon cancer cell migration through activation of its cognate prostaglandin (Buchanan et al, 2003;Hawcroft et al, 2012). Overall our data suggests that the modest defect in cancer cell motility observed with celecoxib treatment indicates that Cox-2-PGE 2 signaling is not the main regulator of GRPstimulated colon cancer cell migration, and most probably it is predominantly controlled by PRG-RhoA-ROCK pathway directly regulating actinomyosin contractile machinery.…”

“…Evidence from in vitro and in vivo studies have shown that Cox-2-PGE 2 signaling increases colon cancer cell migration and invasion (Buchanan et al, 2003;Hawcroft et al, 2012;Ninomiya et al, 2012). Therefore, we wanted to identify the contribution of Cox-2-PGE 2 signaling to overall GRP-stimulated colon cancer cell migration.…”

A liquid chromatography–tandem mass spectrometry method to measure fatty acids in biological samples

“…LC-ESI-MS/MS analysis of hydrolysed lipid extracts from liver samples revealed a significant increase in the % amount of EPA, DPA and DHA, as well as a significant reduction in the relative amount of AA, LA and OA in the liver of mice fed the diet containing 5% (w/w) EPA (figure 5, p<0.05). These FA values are similar to those obtained by GC-MS measurement in a previously published EPA treatment experiment [18]. Therefore, the LC-ESI-MS/MS method can detect omega-3 PUFA changes in mouse tissue following exogenous administration of EPA.…”

“…The relative FA content of MC38 cells exposed to EPA-FFA was measured by GC-MS, as previously described [18,19]. In brief samples, into which internal standard was added (Heneicosanoic acid, 2.5 µg/sample), were homogenized in 0.5 ml saline, then purified by liquid/liquid extraction ( Choroform: Methanol 2:1 vol/vol, 3+2 ml, 0.5% di butylated hydroxytoluene [BHT]) twice.…”

Anticolorectal cancer activity of the omega-3 polyunsaturated fatty acid eicosapentaenoic acid

“…Dietary fish oil has been demonstrated to reduce CRC cell tumour growth 5. We recently tested the effect of EPA-FFA on MC-26 mouse CRC cell liver metastasis (CRCLM) in BALB/c mice 7. We demonstrated that EPA-FFA treatment was associated with reduced liver tumour burden 7…”