CC531s colon carcinoma cells induce apoptosis in rat hepatic endothelial cells by the Fas/FasL-mediated pathway

Fas ligand neutralization attenuates hypertension, endothelin-1, and placental inflammation in an animal model of HELLP syndrome

Neutralization of FasL is linked to suppression of hypertension, placental inflammation, and endothelin system activation in an animal model of hemolysis, elevated liver enzymes, low platelets (HELLP) syndrome. During HELLP syndrome the placenta has been reported to serve as the primary source of Fas ligand (FasL), which has an impact on inflammation and hypertension during pregnancy and is dysregulated in women with severe preeclampsia and HELLP syndrome. We hypothesize that neutralization of FasL during pregnancy in an animal model of HELLP syndrome decreases inflammation and placental apoptosis, improves endothelial damage, and improves hypertension. On gestational day (GD) 12, rats were chronically infused with placental antiangiogenic factors sFlt-1 and sEng to induce HELLP syndrome. To neutralize FasL, MFL4 or FasL antibody was infused into a subset of HELLP or normal pregnant rats on GD13. IgG infusion into another group of NP and HELLP rats on GD13 was used as a control for FasL antibody, and all rats were euthanized on GD19 after blood pressure measurement. Plasma and placentas were collected to assess inflammation, apoptosis, and the degree of placental debris activation of endothelial cells. Administration of MFL4 to HELLP rats significantly decreased blood pressure compared with untreated HELLP rats and HELLP rats infused with IgG and improved the biochemistry of HELLP syndrome. Both circulating and placental FasL were significantly attenuated in response to MFL4 infusion, as were levels of placental and circulating TNFα when compared with untreated HELLP rats and HELLP rats infused with IgG. Endothelial cells exposed to placental debris and media from HP + MFL4 rats secreted significantly less endothelin-1 compared with stimulated endothelial cells from HELLP placentas. Neutralization of FasL is associated with decreased MAP and improvement in placental inflammation and endothelial damage in an animal model of HELLP syndrome.

Mannose-mediated inhibitory effects of PA-MSHA on invasion and metastasis of hepatocellular carcinoma via EGFR/Akt/IκBβ/NF-κB pathway

BACKGROUND & AIMS

Elevation of high-mannose glycans is a common feature of malignant cells and has been suggested to be the basis for alternative cancer therapy for several years. Here we want to investigate the antitumour effect of pseudomonas aeruginosa-mannosesensitive haemagglutinin (PA-MSHA), a genetically engineered heat-inactivated PA strain with mannose-sensitive binding activity, on hepatocellular carcinoma (HCC).

METHODS

Tumourigenicity and metastatic potentials of HCC were studied after PA-MSHA treatment by utilizing the in vitro/in vivo model of HCC. Expression of apoptosis-associated proteins and epithelial-mesenchymal transition (EMT) related genes were evaluated, and possible signalling pathways involved were investigated.

RESULTS

PA-MSHA induced significant cell proliferation inhibition and cell cycle arrest of HCC through decreasing the levels of cyclins D1, cyclins E, CDK2, CDK4, proliferating cell nuclear antigen (PCNA), and increasing the level of p21 and p27. Moreover, PA-MSHA suppressed the invasion, migration and adhesion of HCC through inhibiting epithelial-mesenchymal transition (EMT). PA-MSHA also inhibited EGFR/Akt/IκBβ/NF-κB pathway and overexpression of NF-κB significantly abrogated PA-MSHA induced EMT inhibition. In addition, competitive inhibition of the mannose binding activity of PA-MSHA by D-mannose significantly blocked its effect on cell cycle arrest and EMT. PA-MSHA also abrogated lung metastasis of HCC and significantly inhibited tumour growth in the in vivo study.

CONCLUSIONS

Our study demonstrated the essential role of EGFR/Akt/IκBβ/NF-κB pathway in the inhibitory effect of PA-MSHA on invasion and metastasis of HCC through suppressing EMT, and revealed an attractive prospect of PA-MSHA as a novel candidate agent in the treatment of HCC.

Multifaceted nature of membrane microdomains in colorectal cancer

Membrane microdomains or lipid rafts are known to be highly dynamic and to act as selective signal transduction mediators that facilitate interactions between the cell’s external and internal environments. Lipid rafts play an important mediating role in the biology of cancer: they have been found in almost all existing experimental cancer models, including colorectal cancer (CRC), and play key regulatory roles in cell migration, metastasis, cell survival and tumor progression. This paper explores the current state of knowledge in this field by highlighting some of the pioneering and recent lipid raft studies performed on different CRC cell lines and human tissue samples. From this literature review, it becomes clear that membrane microdomains appear to be implicated in all key intracellular signaling pathways for lipid metabolism, drug resistance, cell adhesion, cell death, cell proliferation and many other processes in CRC. All signal transduction pathways seem to originate directly from those peculiar lipid islands, thereby orchestrating the colon cancer cells’ state and fate. As confirmed by recent animal and preclinical studies in different CRC models, continuing to unravel the structure and function of lipid rafts - including their associated complex signaling pathways - will likely bring us one step closer to better monitoring and treating of colon cancer patients.

Marie R, Wang TC, Lyle S, Kurt-Jones E, Houghton J. Human and mouse colon cancer utilizes CD95 signaling for local growth and metastatic spread to liver

BACKGROUND & AIMS

Analysis of clinical colon cancer specimens show alterations in the CD95 (Fas Ag/Fas L) pathway as tumors progress from local to metastatic disease, suggesting that this pathway may play a role in invasive behavior of colon cancer. However, direct causality between these alterations and clinical disease progression has not been shown.

METHODS

Surgically resected metastatic colon cancer samples were evaluated for Fas Ag/L and apoptosis. Alterations in the Fas-signaling pathway found in human samples were recreated through a series of staged transfection experiments in the MC38 mouse colon cancer cell line and the effects on growth tested in vitro and in vivo.

RESULTS

Expression of FLICE-like inhibitory protein confers apoptosis resistance, increasing the incidence of primary tumors through a survival advantage by avoiding apoptosis and inducing Fas-mediated proliferation. Coexpression of Fas L enables colon cancer cells to metastasize to the liver from local tumors as well as from intravenous injection of cells. MC38-FasL/FLICE-like inhibitory protein colon cancer cells induce apoptosis in hepatocytes via activation of type II Fas Ag signaling, thus creating a niche conducive to tumor growth and fueling their own growth via Fas proliferative signaling.

CONCLUSIONS

Alterations in the Fas Ag pathway which inhibit apoptosis and increase Fas-mediated proliferation directly increase local colon cancer growth, and enhance metastasis to the liver. Delineating points in the pathway responsible for growth and metastasis will offer targets that may be exploited for therapy.

Hepatic sinusoidal cells in health and disease: update from the 14th International Symposium

This review aims to give an update of the field of the hepatic sinusoid, supported by references to presentations given at the 14th International Symposium on Cells of the Hepatic Sinusoid (ISCHS2008), which was held in Tromsø, Norway, August 31-September 4, 2008. The subtitle of the symposium, 'Integrating basic and clinical hepatology', signified the inclusion of both basal and applied clinical results of importance in the field of liver sinusoidal physiology and pathophysiology. Of nearly 50 oral presentations, nine were invited tutorial lectures. The authors of the review have avoided writing a 'flat summary' of the presentations given at ISCHS2008, and instead focused on important novel information. The tutorial presentations have served as a particularly important basis in the preparation of this update. In this review, we have also included references to recent literature that may not have been covered by the ISCHS2008 programme. The sections of this review reflect the scientific programme of the symposium (http://www.ub.uit.no/munin/bitstream/10037/1654/1/book.pdf): 1. Liver sinusoidal endothelial cells. 2. Kupffer cells. 3. Hepatic stellate cells. 4. Immunology. 5. Tumor/metastasis. Symposium abstracts are referred to by a number preceded by the letter A.

The prometastatic microenvironment of the liver

The liver is a major metastasis-susceptible site and majority of patients with hepatic metastasis die from the disease in the absence of efficient treatments. The intrahepatic circulation and microvascular arrest of cancer cells trigger a local inflammatory reaction leading to cancer cell apoptosis and cytotoxicity via oxidative stress mediators (mainly nitric oxide and hydrogen peroxide) and hepatic natural killer cells. However, certain cancer cells that resist or even deactivate these anti-tumoral defense mechanisms still can adhere to endothelial cells of the hepatic microvasculature through proinflammatory cytokine-mediated mechanisms. During their temporary residence, some of these cancer cells ignore growth-inhibitory factors while respond to proliferation-stimulating factors released from tumor-activated hepatocytes and sinusoidal cells. This leads to avascular micrometastasis generation in periportal areas of hepatic lobules. Hepatocytes and myofibroblasts derived from portal tracts and activated hepatic stellate cells are next recruited into some of these avascular micrometastases. These create a private microenvironment that supports their development through the specific release of both proangiogenic factors and cancer cell invasion- and proliferation-stimulating factors. Moreover, both soluble factors from tumor-activated hepatocytes and myofibroblasts also contribute to the regulation of metastatic cancer cell genes. Therefore, the liver offers a prometastatic microenvironment to circulating cancer cells that supports metastasis development. The ability to resist anti-tumor hepatic defense and to take advantage of hepatic cell-derived factors are key phenotypic properties of liver-metastasizing cancer cells. Knowledge on hepatic metastasis regulation by microenvironment opens multiple opportunities for metastasis inhibition at both subclinical and advanced stages. In addition, together with metastasis-related gene profiles revealing the existence of liver metastasis potential in primary tumors, new biomarkers on the prometastatic microenvironment of the liver may be helpful for the individual assessment of hepatic metastasis risk in cancer patients.

Interactions between colon cancer cells and hepatocytes in rats in relation to metastasis

Adhesion of cancer cells to endothelium is considered an essential step in metastasis. However, we have shown in a previous study that when rat colon cancer cells are administered to the vena portae, they get stuck mechanically in liver sinusoids. Then, endothelial cells retract rapidly and cancer cells bind to hepatocytes. We investigated the molecular nature of these interactions between colon cancer cells and hepatocytes. Cancer cells in coculture with hepatocytes became rapidly activated with distinct morphological changes. Cancer cells formed long cytoplasmic protrusions towards hepatocytes in their close vicinity and these protrusions attached to microvilli of hepatocytes. Then, adhering membrane areas were formed by both cell types. Integrin subunits alphav, alpha6 and beta1 but not alphaL, beta2, beta3 and CD44 and CD44v6 were expressed on the cancer cells. In conclusion, colon cancer cells show an active behaviour to bind to hepatocytes, likely involving the integrin subunits alphav, alpha6 and beta1, indicating that early events in colon cancer metastasis in liver are distinctly different than assumed thus far.

The hepatic sinusoidal endothelial lining and colorectal liver metastases

Colorectal cancer (CRC) is a common malignant disease and the severe nature of cases in men and women who develop colorectal cancer makes this an important socio-economic health issue. Major challenges such as understanding and modeling colorectal cancer pathways rely on our understanding of simple models such as outlined in this paper. We discuss that the development of novel standardized approaches of multidimensional (correlative) biomolecular microscopy methods facilitates the collection of (sub) cellular tissue information in the early onset of colorectal liver metastasis and that this approach will be crucial in designing new effective strategies for CRC treatment. The application of X-ray micro-computed tomography and its potential in correlative imaging of the liver vasculature will be discussed.

Structural and functional aspects of the liver and liver sinusoidal cells in relation to colon carcinoma metastasis

Nowadays, liver metastasis remains difficult to cure. When tumor cells escape and arrive in the liver sinusoids, they encounter the local defense mechanism specific to the liver. The sinusoidal cells have been widely described in physiologic conditions and in relation to metastasis during the past 30 years. This paper provides an “overview” of how these cells function in health and in diseases such as liver metastasis.

Liver immunobiology

Tle liver has a number of important functions in innate and adaptive immunity. Contributions to the innate (nonspecific) immune system include production of acute phase proteins, nonspecific phagocytosis of particles, nonspecific pinocytosis of molecules, and nonspecific cell killing. Hepatic involvement in innate immunity contributes to the systemic response to local inflammation, clearance of particles and soluble molecules from the circulation, and killing of invading cells such as neoplastic cells. Liver involvement in the adaptive (specific) immune system includes deletion of activated T cells, induction of tolerance to ingested and self-antigens, extrathymic proliferation of T cells, and deletion of many of the signaling and effector molecules. Hepatic involvement in adaptive immunity allows clearance of activated T cells and signaling molecules following inflammatory reactions, and promotes immunologic tolerance toward potentially antigenic proteins that are absorbed from the intestinal tract. The liver is a major site of extrathymic T cell development, which assumes increasing significance with aging in mammals. Perturbations in hepatic structure or function can result in significant ramifications in both the innate and adaptive immune systems.

Interactions between rat colon carcinoma cells and Kupffer cells during the onset of hepatic metastasis

Liver sinusoids harbor populations of 2 important types of immunocompetent cells, Kupffer cells (KCs) and natural killer (NK) cells, which are thought to play an important role in controlling hepatic metastasis in the first 24 hr upon arrival of the tumor cells in the liver. We studied the early interaction of KCs, NK and CC531s colon carcinoma cells in a syngeneic rat model by confocal laser scanning microscopy. Results showed a minority of KCs (19% periportal and 7% pericentral) involved in the interaction with 94% of tumor cells and effecting the phagocytosis of 92% of them. NK cell depletion decreased the phagocytosis of tumor cells by KCs by 33% over a period of 24 hr, leaving 35% of the cancer cells free, as compared to 6% in NK-positive rats. Surviving cancer cells were primarily located close to the Glisson capsule, suggesting that metastasis would initiate from this region.

Nitric oxide from rat liver sinusoidal endothelial cells induces apoptosis in IFN gamma-sensitized CC531s colon carcinoma cells

BACKGROUND/AIMS

Investigation of apoptosis is pivotal in searching for mechanisms that eliminate colon cancer cells getting trapped in liver sinusoids at the time of surgical removal of the primary tumor. This study focuses on nitric oxide (NO), Fas/FasL and the involvement of interferon-gamma (IFNgamma) in liver sinusoidal endothelial cells (LSECs) and in the colon carcinoma cell line CC531s.

METHODS

Apoptosis was quantified and visualized in vitro by specific DNA fragmentation, specific staining and electron microscopy. In vivo experiments were also conducted.

RESULTS

In co-cultures of LSECs with CC531s, apoptosis of CC531s was observed only when they were pre-treated with IFNgamma, and was unaffected by blocking the Fas/FasL pathway. However, LSECs continuously produced NO, and apoptosis was inhibited by NO-inhibitors (NMMA and dexamethasone). When IFNgamma-sensitized CC531s were injected into rats, liver weight was lower, in contrast to control conditions where liver weight was higher.

CONCLUSIONS

(i) LSECs induce apoptosis in IFNgamma-sensitized CC531s in vitro; (ii) LSECs express FasL; (iii) Fas on CC531s becomes active after IFNgamma-treatment; however, (iv) blocking the Fas/FasL pathway had no effect; (v) apoptosis was inhibited by NO-inhibitors; (vi) the immune system uses this IFNgamma-activated pathway to support LSECs in killing tumor cells.