Carcinoembryonic antigen induction of IL‐10 and IL‐6 inhibits hepatic ischemic/reperfusion injury to colorectal carcinoma cells

Abstract

Tumor cells cause ischemia/reperfusion (I/R) injury as they arrest within the hepatic microvasculature with the production of nitric oxide (NO) and reactive oxygen species (ROS) that kill both host liver and implanting tumor cells. Carcinoembryonic antigen (CEA) both facilitates the survival of experimental metastasis to nude mouse liver by weakly metastatic human colorectal carcinomas (CRCs) and induces the release of the proinflammatory cytokine IL-6. We hypothesized that CEA also stimulates the release of the antiinflammatory cytokine IL-10 causing inhibition of the toxicity of hepatic I/R injury and indirect stimulation of tumor cell colonization of the liver. Intravenous injection of CEA produced more than 1 ng/ml of IL-10 in the systemic circulation within 1 hr which subsided by 8 hr. The IL-10 response is specific to CEA since the pentapeptide sequence in CEA that binds to the CEA receptor stimulated isolated Kupffer cells to produce IL-10. IL-10, but not IL-6, increased the survival of weakly metastatic CRC cocultured with ischemic-reoxygenated liver fragments but did not affect the survival of CRC exposed to oxidative stress in the absence of any host cells. CEA, IL-6 and IL-10 pretreatment reduced expression of iNOS but only CEA and IL-10 strongly inhibited NO and total reactive species production by ischemic-rexoygenated liver. IL-6 was toxic to CRC exposed to oxidative stress while IL-10 did not have a direct effect on CRC. Thus, CEA stimulates production of IL-10 that may enhance metastasis by promoting the ability of circulating CRC cells to survive the I/R injury of implantation. © 2004 Wiley-Liss, Inc.Key words: metastasis; colorectal carcinoma; ischemia/reperfusion injury; oxidative stress; carcinoembryonic antigen Tumor cells arresting within the hepatic microcirculation must survive several formidable challenges if they are to form metastases successfully. Mechanical deformation kills 50% of arresting tumor cells 1,2 while oxidative stress may kill almost all of the remaining cells. [3][4][5] Oxidative stress is caused by ischemia/reperfusion (I/R) injury when tumor cells entering the hepatic microcirculation obstruct hepatic sinusoids and temporarily occlude blood flow before the hepatic circulation is reestablished by either tumor cell death or invasion into the parenchyma. 6 I/R injury produces nitric oxide (NO) and reactive oxygen species (ROS) 7 that are toxic to both host liver as well as arresting tumor cells. Interestingly, primary explant cultures of murine hepatic sinusoidal endothelial cells constitutively produce NO and superoxide anion that kill tumor cells. 8,9 As a result, weakly metastatic human colorectal carcinoma (CRC) cells are essentially eliminated from the hepatic microcirculation within 4 -24 hr because of their sensitivity to NO and ROS while highly metastatic CRC cells persist within the hepatic microcirculation after 24 hr because of their resistance to NO and ROS. 2,10 Thus, the defense mechanisms that enable tumor cells to resist attack by NO and ROS are import...

Carcinoembryonic antigen (CEA) and its receptor hnRNP M are mediators of metastasis and the inflammatory response in the liver

“…Tumor cells arresting in the liver also produce toxic levels of NO and reactive oxygen species (ROS) due to the creation of local ischemic/reperfusion injury [114]. The release of the antiinflammatory cytokine IL-10 by Kupffer cells activated by CEA also plays a role in tumor cell survival by inhibiting inducible nitric oxide synthetase (iNOS) and the production of NO and ROS, thus aiding tumor cell survival [115,116]. Hypoxia also up-regulates CEA expression in colorectal and breast cancers [117] this could be a defensive mechanism as release of CEA would activate Kupffer cells to produce more IL-10 and protect the cancer cells from the cytotoxic effects of NO and ROS.…”

Carcinoembryonic antigen promotes tumor cell survival in liver through an IL-10-dependent pathway

“…These ischemic-reperfused mice then had their abdomens closed aseptically and were recovered from surgery for 4 h whereupon they were sacrificed and their livers harvested and analyzed for iNOS gene expression and NF-jB activity as described below. Co-cultures were incubated and analyzed for up to 24 h. NO and reactive oxygen species (ROS) were measured by static fluorometry of ischemic liver cells as described by Jessup et al [23] except that measurements were made of the concentration of NO and ROS within CRC liver cells rather than in the medium.…”

“…To assure that inhibition of iNOS was associated with a decrease in NO static fluorometry was performed in hepatic cells cultured in the RWV for 24 h. The intracellular concentrations of both NO and ROS were assessed by fluorescence microscopy with cell permeant dyes that measure either NO (DAF-FM diacetate) or total ROS as both Superoxide anion and hydrogen peroxide species (CM-H 2 DCFDA -Molecular Probes) [23]. Ischemic nude mouse liver incubated and reoxygenated in the RWV from mice that were either pretreated with CEA, rhIL-6, rhIL-10 or left untreated were cultured for 24 h. Liver cells and media were then collected and the amount of intracellular NO and ROS measured.…”

“…This model system permits the donor mouse to be pretreated in vivo and then the effects on the liver analyzed in vitro. CEA induces the systemic production of both the pro-inflammatory cytokine IL-6 and the anti-inflammatory cytokine IL-10 in nude mice within 30 min of CEA injection, peaking at 1-1.5 h, and disappearing from the blood about 8 h after initial injection [21][22][23]. IL-10 promoted the survival of weakly metastatic human clone A CRC cells exposed to ischemic/reoxygenated liver more than IL-6 did -although both inhibited RNOS production [23].…”

“…CEA induces the systemic production of both the pro-inflammatory cytokine IL-6 and the anti-inflammatory cytokine IL-10 in nude mice within 30 min of CEA injection, peaking at 1-1.5 h, and disappearing from the blood about 8 h after initial injection [21][22][23]. IL-10 promoted the survival of weakly metastatic human clone A CRC cells exposed to ischemic/reoxygenated liver more than IL-6 did -although both inhibited RNOS production [23]. In the present study we investigated whether the CEA effect required Kupffer cell function and then which cytokine -IL-10 or IL-6 -was more important for preventing the cytotoxicity from I/R injury.…”