Surgery-stimulated tumor growth : preclinical and clinical studies on colorectal liver metastases

In the Netherlands, every year 12.000 new patients are diagnosed with colorectal cancer. In approximately 50% of cases liver metastases will develop. In this thesis, we first address the role of oncogenic K-Ras on the development of liver metastases. K-Ras is a frequently mutated gene in colon cancer. We demonstrate that a mutation in K-Ras contributes to liver metastases formation based on a switch in death receptor signaling, which is an important defense mechanism of the liver. Colon carcinoma cells harboring a K-Ras mutation do not die in response to death receptor signaling (i.e. CD95- and TRAIL-receptor signaling) which normally occurs. Instead, colon cancer cells with the K-Ras mutation show an invasive phenotype upon death receptor signaling and increased survival in the liver based on reduced signaling of the Rho-ROCK-LIMK-cofilin pathway mediated by Raf-1. In patients, once metastases have formed, liver surgery is the only curative treatment option. Unfortunately, the disease will recur in approximately 70% of the cases. In this thesis, we mainly focused on the role of liver surgery itself on tumor recurrence in the liver. The effects of two distinct surgical interventions in the liver (radiofrequency ablation and vascular clamping) on residual tumor tissue have been investigated using a highly standardized mouse model. We demonstrated that the outgrowth of tumor cells that were located in the rim of induced necrosis was approximately 4 times faster than tumor cells that were located elsewhere in the liver. It was demonstrated that surgery-induced hypoxia (low oxygen) plays an important role in the accelerated tumor outgrowth following the surgical interventions in the liver based on stabilization of Hypoxia Inducible Factors (HIFs). Moreover, aforementioned autocrine CD95 signaling of the tumor cells in the rim of the necrosis by hypoxia was responsible for the observed invasion and accelerated outgrowth of tumor cells. Finally, we demonstrated in patients with colorectal liver metastases that severe ischemia (resulting in hypoxia) during partial liver resections was associated with a reduced time to tumor recurrence in the liver. In conclusion, our results increase the understanding how liver surgery affects residual tumor tissue. The role of hypoxia and subsequent HIF stabilization and/or CD95 activation is important in this phenomenon

Ig-Free Light Chains Play a Crucial Role in Murine Mast Cell-Dependent Colitis and Are Associated with Human Inflammatory Bowel Diseases

Traditionally, mast cells were regarded as key cells orchestrating type I hypersensitivity responses. However, it is now recognized that mast cells are widely involved in nonallergic (non-IgE) chronic diseases. Also, in inflammatory bowel disease (IBD), a disease not associated with increased IgE concentrations, clear signs of activation of mast cells have been found. In this study, we investigated if Ig-free L chain-induced hypersensitivity-like responses through activation of mast cells could contribute to the pathophysiology of IBD. As a mast cell-dependent model for IBD, mice were skin-sensitized with dinitrofluorobenzene followed by intrarectal application of the hapten. In this murine IBD model, F991 prevented mast cell activation and also abrogated the development of diarrhea, cellular infiltration, and colonic lymphoid follicle hyperplasia. Furthermore, passive immunization with Ag-specific Ig-free L chains (IgLCs) and subsequent rectal hapten challenge elicited local mast cell activation and increased vascular permeability in the colon of mice. Clinical support is provided by the observation that serum concentrations of IgLCs of patients suffering from Crohn's disease are greatly increased. Moreover, increased presence of IgLCs was evident in tissue specimens from colon and ileum tissue of patients with IBD. Our data suggest that IgLCs may play a role in the pathogenesis of IBD, which provides novel therapeutic means to prevent or ameliorate the adverse gastrointestinal manifestations of IBD. The Journal of Immunology, 2010, 185: 653-659.Cellular mechanisms in basic and clinical gastroenterology and hepatolog

Differentiated Human Colorectal Cancer Cells Protect Tumor-Initiating Cells From Irinotecan

BACKGROUND & AIMS: Stem cells of normal tissues have resistance mechanisms that allow them to survive genotoxic insults. The stem cell-like cells of tumors are defined by their tumor-initiating capacity and may have retained these resistance mechanisms, making them resistant to chemotherapy. We studied the relationship between resistance to the topoisomerase I inhibitor irinotecan and tumor-initiating potential in human colonosphere cultures and in mice with colorectal xenograft tumors. METHODS: Colonosphere cultures were established from human colorectal tumor specimens obtained from patients who underwent colon or liver resection for primary or metastatic adenocarcinoma. Stem cell and differentiation markers were analyzed by immunoblotting and fluorescence-activated cell sorting. Clone- and tumor-initiating capacities were assessed by single-cell cloning and in immune-deficient mice. Sensitivity to irinotecan was assessed in vitro and in tumor-bearing mice. The relationship between drug resistance and tumor-initiating capacity was tested by fluorescence-activated cell sorting of colonosphere cells, based on expression of ABCB1 and aldehyde dehydrogenase (ALDH) activity. RESULTS: Colonosphere cultures had a high capacity to initiate tumors in mice and were resistant to irinotecan. Inhibition of the drug-efflux pump ABCB1 by PSC-833 allowed irinotecan to eradicate tumor-initiating cells. However, ABCB1 was expressed only by a subpopulation of differentiated tumor cells that did not form clones or tumors. Conversely, tumor-initiating cells were ABCB1-negative and were identified by high ALDH activity. Tumorigenic ALDHhigh/ABCB1negative cells generated nontumorigenic ALDHlow/ABCB1positive daughter cells in vitro and in tumor xenografts. PSC-833 increased the antitumor efficacy of irinotecan in mice. CONCLUSIONS: The resistance of colorectal tumors to irinotecan requires the cooperative action of tumor-initiating ALDHhigh/ABCB1negative cells and their differentiated, drug-expelling, ALDHlow/ABCB1positive daughter cells. [KEYWORDS: Adenocarcinoma/ drug therapy/metabolism/secondary, Aldehyde Dehydrogenase/metabolism, Animals, Antineoplastic Agents, Phytogenic/metabolism/ pharmacology, Blotting, Western, Camptothecin/ analogs & derivatives/metabolism/pharmacology, Cell Differentiation/ drug effects, Colonic Neoplasms/ drug therapy/metabolism/pathology, Cyclosporins/pharmacology, Dose-Response Relationship, Drug, Drug Resistance, Neoplasm/drug effects, Flow Cytometry/methods, Humans, Liver Neoplasms/ drug therapy/

Immunoglobulin-free light chains elicit immediate hypersensitivity-like responses

Immunoglobulin-free light chains elicit immediate hypersensitivity-like responses.Redegeld FA, van der Heijden MW, Kool M, Heijdra BM, Garssen J, Kraneveld AD, Van Loveren H, Roholl P, Saito T, Verbeek JS, Claassens J, Koster AS, Nijkamp FP.Department of Pharmacology and Pathophysiology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Utrecht, the Netherlands. [email protected] (Ig)-free light chains IgLC are present in serum and their production is augmented under pathological conditions such as multiple sclerosis, rheumatoid arthritis and neurological disorders. Until now, no (patho)physiological function has been ascribed to circulating Ig light chains. Here we show that IgLCs can confer mast cell dependent hypersensitivity in mice. Antigenic stimulation results in plasma extravasation, cutaneous swelling and mast-cell degranulation. We show that IgLCs have a crucial role in development of contact sensitivity, which could be completely prevented by a novel IgLC antagonist. Although IgE and IgG(1) are central to the induction of immediate hypersensitivity reactions, our results show that IgLCs have similar activity. IgLCs may therefore be a novel factor in the humoral immune response to antigen exposure. Our findings open new avenues in investigating the pathogenesis of autoimmune diseases and their treatments.<br/

Intra-observer agreements in multidisciplinary team assessments of pancreatic cancer patients

Background and Methods Treatment strategies for pancreatic cancer patients are made by a multidisciplinary team (MDT) board. We aimed to assess intra-observer variance at MDT boards. Participating units staged, assessed resectability, and made treatment allocations for the same patients as they did two years earlier. We disseminated clinical information and CT images of pancreatic cancer patients judged by one MDT board to have nonmetastatic pancreatic cancer to the participating units. All units were asked to re-assess the TNM stage, resectability, and treatment allocation for each patient. To assess intra-observer variance, we computed %-agreements for each participating unit, defined as low (75%) agreement. Results Eighteen patients were re-assessed by six MDT boards. The overall agreement was moderate for TNM-stage (ranging from 50%-70%) and resectability assessment (53%) but low for treatment allocation (46%). Agreement on resectability assessments was low to moderate. Findings were similar but more pronounced for treatment allocation. We observed a shift in treatment strategy towards increasing use of neoadjuvant chemotherapy, particularly in patients with borderline resectable and locally advanced tumors. Conclusions We found substantial intra-observer agreement variations across six different MDT boards of 18 pancreatic cancer patients with two years between the first and second assessment