Activation of cellular invasion by trefoil peptides and src is mediated by cyclooxygenase‐ and thromboxane A2 receptor‐dependent signaling pathways

Abstract

We have investigated the possible functional relationships between cellular invasion pathways induced by trefoil factors (TFFs), src, and the cyclooxygenases COX-1 and COX-2. Pharmacological inhibitors of the Rho small GTPase (C3 exoenzyme), phospholipase C (U-73122), cyclooxygenases (SC-560, NS-398), and the thromboxane A2 receptor (TXA2-R) antagonist SQ-295 completely abolished invasion induced by intestinal trefoil factor, pS2, and src in kidney and colonic epithelial cells MDCKts.src and PCmsrc. In contrast, invasion was induced by the TXA2-R mimetic U-46619, constitutively activated forms of the heterotrimeric G-proteins Galphaq (AGalphaq), Galpha12, Galpha13 (AGalpha12/13), which are signaling elements downstream of TXA2-R. Ectopic overexpression of pS2 cDNA and protein in MDCKts.src-pS2 cells and human colorectal cancer cells HCT8/S11-pS2 initiate distinct invasion signals that are Rho independent and COX and TXA2-R dependent. We detected a marked induction of COX-2 protein and accumulation of the stable PGH2/TXA2 metabolite TXB2 in the conditioned medium from cells transformed by src. This led to activation of the TXA2-R-dependent invasion pathway, which is monitored via a Rho- and Galpha12/Galpha13-independent mechanism using the Galphaq/PKC signaling cascade. These findings identify a new intracrine/paracrine loop that can be monitored by TFFs and src in inflammatory diseases and progression of colorectal cancers.

Induction of the adenoma-carcinoma progression and Cdc25A-B phosphatases by the trefoil factor TFF1 in human colon epithelial cells

“…To gain insight into the mechanisms linked to the transforming potential of TFF1, we showed that constitutive expression of TFF1 induced anchorageindependent cell growth in soft agar and cellular invasion through several proinvasive signaling pathways, including Rho-GTPases, Rho-kinase, PI3-kinase, PLC and COX-2. This picture is reminiscent to our TFF1 transforming functions and Cdc25 phosphatases S Rodrigues et al previous data on invasion and angiogenesis induced by external addition of the intact peptide TFF1 (Emami et al, 2001;Rodrigues et al, 2001Rodrigues et al, , 2003b. Moreover, TFF1 overexpression induced resistance to apoptosis, as shown here by PARP cleavage and persistence of the two anti-apoptotic proteins Bcl-2 and MDM2.…”

“…These invasive responses observed in PC-TFF1 and MDCKts.src-TFF1 cells are blocked by pharmacological inhibitors targeting several oncogenic pathways implicated in cell motility, invasion and survival, including Rho GTPases (C3T, 3 mg/ml), Rho-kinase (Y27632, 10 mM), PI3 0 -kinase (WORT, 10 nM), PLCb (U73122, 1 mM), and COX-2 (NS398, 25 mM). According to our previous report (Rodrigues et al, 2001), TFF1 overexpression was associated with increased levels of the COX-2 protein.…”

“…HCT8/S11 colon cancer cells were cultured in RPMI-1640 containing 10% FCS (Rodrigues et al, 2001). MCF-7 were also cultured under growth factor-free, estrogen-free and hypoxic conditions using the OXOID incubator chamber (Basingtoke, Hamshire, England).…”

“…In contrast, TFF1 is absent in normal colon but is induced at high levels in Crohn disease and colorectal cancers (Emami et al, 2004). Recent studies incriminate TFF1 and other TFFs in the neoplastic progression of the digestive system, according to their scattering, proinvasive and proangiogenic activities in vitro and in vivo (Emami et al, 2001;Rodrigues et al, 2001Rodrigues et al, , 2003bRivat et al, 2005). All TFF members are implicated in cancer cell survival, suggesting that they participate to the aggressive behavior and metastatic potential of colon cancer cells (Taupin et al, 2000;BossenmeyerPourie et al, 2002;Yio et al, 2005).…”

Commutators of PAR-1 signaling in cancer cell invasion reveal an essential role of the Rho–Rho kinase axis and tumor microenvironment

“…As shown in Figure 1d, both parental and DN-ROK-transfected HCT8/S11 cells were noninvasive under control conditions. Interestingly, the dominant negative form of ROK established the proinvasive activity of PAR-1, but failed to produce the same response following activation of the G-protein-coupled PAF-R. As expected (Rodrigues et al, 2001), DN-ROK abrogated the proinvasive activities of pS2 and leptin (Figure 1d), whereas DC-ROK was ineffective. We confirmed that this dominant active mutant was functionally competent in our system since DC-ROK abrogated insulin-induced invasion.…”