Marcel Verheij

Ceramide: second messenger or modulator of membrane structure and dynamics?

The physiological role of ceramide formation in response to cell stimulation remains controversial. Here, we emphasize that ceramide is not a priori an apoptotic signalling molecule. Recent work points out that the conversion of sphingomyelin into ceramide can play a membrane structural (physical) role, with consequences for membrane microdomain function, membrane vesiculation, fusion/fission and vesicular trafficking. These processes contribute to cellular signalling. At the Golgi, ceramide takes part in a metabolic flux towards sphingomyelin, diacylglycerol and glycosphingolipids, which drives lipid raft formation and vesicular transport towards the plasma membrane. At the cell surface, receptor clustering in lipid rafts and the formation of endosomes can be facilitated by transient ceramide formation. Also, signalling towards mitochondria may involve glycosphingolipid-containing vesicles. Ceramide may affect the permeability of the mitochondrial outer membrane and the release of cytochrome c. In the effector phase of apoptosis, the breakdown of plasma membrane sphingomyelin to ceramide is a consequence of lipid scrambling, and may regulate apoptotic body formation. Thus ceramide formation serves many different functions at distinct locations in the cell. Given the limited capacity for spontaneous intracellular diffusion or membrane flip-flop of natural ceramide species, the topology and membrane sidedness of ceramide generation are crucial determinants of its impact on cell biology.

Gastric cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up

Gastric cancer: ESMO Clinical Practice Guidelines for diagnosis, treatment and follow-up A. Okines, M. Verheij, W. Allum, D. Cunningham & A. Cervantes On behalf of the ESMO Guidelines Working Group* GI Clinical Trials Unit, Royal Marsden Hospital, Sutton, UK; Department of Radiation Oncology and Division of Cellular Biochemistry, The Netherlands Cancer Institute—Antoni van Leeuwenhoek Hospital, Amsterdam, The Netherlands; Department of Surgery, Royal Marsden Hospital, London; Department of Medicine, Royal Marsden Hospital, Sutton, UK; Department of Hematology and Medical Oncology, INCLIVA, University of Valencia, Valencia, Spain

Radiation-induced apoptosis

Abstract Radiation-induced apoptosis has been a topic of intense research during the last decade. Its recognition as a significant component of radiation-induced cell death has initiated several lines of investigation aimed at modulating the apoptotic response and thereby radiosensitivity. These strategies require the integration of both classical radiobiological concepts and the knowledge of the biochemical and molecular biological mechanisms involved in apoptosis induction. This review discusses mechanisms of radiation-induced apoptosis and highlights the radiobiological and radiotherapeutical relevance of this mode of cell death.

Anti-cancer alkyl-lysophospholipids inhibit the phosphatidylinositol 3-kinase-Akt/PKB survival pathway.

Synthetic alkyl-lysophospholipids (ALPs) represent a new class of anti-tumor agents that target cell membranes and induce apoptosis. However, the exact mechanisms by which ALPs exert these effects remain unclear. Here, we investigated in the epithelial carcinoma cell lines A431 and HeLa the effect of three clinically relevant ALPs [Et-18-OCH3 (Edelfosine), HePC (Miltefosine) and D-21266 (Perifosine)] on the phosphatidylinositol 3-kinase (PI3K)–Akt/PKB survival pathway. We found that growth factor-induced Akt/PKB activation in these cells is dependent on PI3K and that all three ALPs inhibited this pathway in a dose-dependent manner. We further showed that inhibition of the PI3K–Akt/PKB pathway by wortmannin or ALPs is associated with activation of the pro-apoptotic SAPK/JNK pathway. Inhibition of the PI3K–Akt/PKB survival pathway represents a novel mode of action of ALPs that may significantly contribute to the induction of apoptosis.

Selection of patients for radiotherapy with protons aiming at reduction of side effects: The model-based approach

Most new radiation techniques, have been introduced primarily to reduce the dose to normal tissues in order to prevent radiation-induced side effects. Radiotherapy with protons is such a radiation technique that due to its superior beam properties compared to photons enables better sparing of normal tissues. This paper describes a stepwise methodology to select patients for proton therapy when the primary aim is to reduce side effects. This method has been accepted by the Dutch health authorities to select patients for proton therapy. In addition, an alternative method is described in case randomised controlled trials are considered not appropriate.

Neo-adjuvant chemotherapy followed by surgery and chemotherapy or by surgery and chemoradiotherapy for patients with resectable gastric cancer (CRITICS)

BackgroundRadical surgery is the cornerstone in the treatment of resectable gastric cancer. The Intergroup 0116 and MAGIC trials have shown benefit of postoperative chemoradiation and perioperative chemotherapy, respectively. Since these trials cannot be compared directly, both regimens are evaluated prospectively in the CRITICS trial. This study aims to obtain an improved overall survival for patients treated with preoperative chemotherapy and surgery by incorporating radiotherapy concurrently with chemotherapy postoperatively.Methods/designIn this phase III multicentre study, patients with resectable gastric cancer are treated with three cycles of preoperative ECC (epirubicin, cisplatin and capecitabine), followed by surgery with adequate lymph node dissection, and then either another three cycles of ECC or concurrent chemoradiation (45 Gy, cisplatin and capecitabine). Surgical, pathological, and radiotherapeutic quality control is performed. The primary endpoint is overall survival, secondary endpoints are disease-free survival (DFS), toxicity, health-related quality of life (HRQL), prediction of response, and recurrence risk assessed by genomic and expression profiling. Accrual for the CRITICS trial is from the Netherlands, Sweden, and Denmark, and more countries are invited to participate.ConclusionResults of this study will demonstrate whether the combination of preoperative chemotherapy and postoperative chemoradiotherapy will improve the clinical outcome of the current European standard of perioperative chemotherapy, and will therefore play a key role in the future management of patients with resectable gastric cancer.Trial registrationclinicaltrials.gov NCT00407186

High Response Rates and Lasting Remissions After Low-Dose Involved Field Radiotherapy in Indolent Lymphomas

PURPOSE To study the response rates and duration of response after low-dose (4 Gy) involved field radiotherapy (LD-IF-RT) in patients with recurrent indolent lymphoma. PATIENTS AND METHODS A total of 109 assessable patients (304 symptomatic sites) were irradiated (53 males and 56 females; median age, 62 years; range, 35 to 93), including 98 patients with follicular lymphoma (43 grade 1 and 55 grade 2), nine extranodal marginal zone lymphomas of mucosa-associated lymphoid tissue-type and two patients with lymphoplasmacytoid lymphoma. Bulky disease (> or =5 cm) was present in 52% of all patients. A median of two prior regimens (range, 0 to 11) preceded LD-IF-RT. The median time since diagnosis was 41 months (range, 2 to 358 months). Time to (local) progression was calculated according to the Kaplan-Meier method. Differences in response rates between treatments within the same patient were compared using the McNemar test. RESULTS The overall response rate was 92%; complete response was reached in 67 patients (61%), partial response in 34 patients (31%), stable disease in six patients (6%), and progressive disease in two patients (2%). The median time to progression was 14 months. The median time to local progression was 25 months. The 67 patients with complete response showed a median time to progression of 25 months and a median time to local progression of 42 months. None of the factors studied (age, sex, follicular lymphoma grade, radiotherapy regimen, number of previous regimens and previous history, number of positive sites or largest lymphoma diameter) were found to be related to response rate. CONCLUSION LD-IF-RT is a valuable asset in the management of patients with follicular lymphoma and should be considered in patients with recurrent disease.

Impact of the Extent of Surgery and Postoperative Chemoradiotherapy on Recurrence Patterns in Gastric Cancer

PURPOSE The Intergroup 0116 trial has demonstrated that postoperative chemoradiotherapy (CRT) improves survival in gastric cancer. We retrospectively compared survival and recurrence patterns in two phase I/II studies evaluating more intensified postoperative CRT with those from the Dutch Gastric Cancer Group Trial (DGCT) that randomly assigned patients between D1 and D2 lymphadenectomy. PATIENTS AND METHODS Survival and recurrence patterns of 91 patients with adenocarcinoma of the stomach who had received surgery followed by radiotherapy combined with fluorouracil and leucovorin (n = 5), capecitabine (n = 39), or capecitabine and cisplatin (n = 47) were analyzed and compared with survival and recurrence patterns of 694 patients from the DGCT (D1, n = 369; D2, n = 325). For both groups, the Maruyama Index of Unresected Disease (MI) was calculated and correlated with survival and recurrence patterns. RESULTS With a median follow-up of 19 months in the CRT group, local recurrence rate after 2 years was significantly higher in the surgery only (DGCT) group (17% v 5%; P = .0015). Separate analysis of CRT patients who underwent a D1 dissection (n = 39) versus DGCT-D1 (n = 369) showed fewer local recurrences after chemoradiotherapy (2% v 8%; P = .001), whereas comparison of CRT-D2 (n = 25) versus DGCT-D2 (n = 325) demonstrated no significant difference. CRT significantly improved survival after a microscopically irradical (R1) resection. The MI was found to be a strong independent predictor of survival. CONCLUSION After D1 surgery, the addition of postoperative CRT had a major impact on local recurrence in resectable gastric cancer.

Alkyl-lysophospholipid Accumulates in Lipid Rafts and Induces Apoptosis via Raft-dependent Endocytosis and Inhibition of Phosphatidylcholine Synthesis

The synthetic alkyl-lysophospholipid (ALP), 1-O-octadecyl-2-O-methyl-rac-glycero-3-phosphocholine, is an antitumor agent that acts on cell membranes and can induce apoptosis. We investigated how ALP is taken up by cells, how it affectsde novo biosynthesis of phosphatidylcholine (PC), and how critical this is to initiate apoptosis. We compared an ALP-sensitive mouse lymphoma cell line, S49, with an ALP-resistant variant, S49AR. ALP inhibited PC synthesis at the CTP:phosphocholine cytidylyltransferase (CT) step in S49 cells, but not in S49AR cells. Exogenous lysophosphatidylcholine, providing cells with an alternative way (acylation) to generate PC, rescued cells from ALP-induced apoptosis, indicating that continuous rapid PC turnover is essential for cell survival. Apoptosis induced by other stimuli that do not target PC synthesis remained unaffected by lysophosphatidylcholine. Using monensin, low temperature and albumin back-extraction, we demonstrated that ALP is internalized by endocytosis, a process defective in S49AR cells. This defect neither involved clathrin-coated pit- nor fluid-phase endocytosis, but depended on lipid rafts, because disruption of these microdomains with methyl-β-cyclodextrin or filipin (sequestering cholesterol) or bacterial sphingomyelinase reduced uptake of ALP. Furthermore, ALP was found accumulated in isolated rafts and disruption of rafts also prevented the inhibition of PC synthesis and apoptosis induction in S49 cells. In summary, ALP is internalized by raft-dependent endocytosis to inhibit PC synthesis, which triggers apoptosis.

A new class of anticancer alkylphospholipids uses lipid rafts as membrane gateways to induce apoptosis in lymphoma cells

Single-chain alkylphospholipids, unlike conventional chemotherapeutic drugs, act on cell membranes to induce apoptosis in tumor cells. We tested four different alkylphospholipids, i.e., edelfosine, perifosine, erucylphosphocholine, and compound D-21805, as inducers of apoptosis in the mouse lymphoma cell line S49. We compared their mechanism of cellular entry and their potency to induce apoptosis through inhibition of de novo biosynthesis of phosphatidylcholine at the endoplasmic reticulum. Alkylphospholipid potency closely correlated with the degree of phosphatidylcholine synthesis inhibition in the order edelfosine > D-21805 > erucylphosphocholine > perifosine. In all cases, exogenous lysophosphatidylcholine, an alternative source for cellular phosphatidylcholine production, could partly rescue cells from alkylphospholipid-induced apoptosis, suggesting that phosphatidylcholine biosynthesis is a direct target for apoptosis induction. Cellular uptake of each alkylphospholipid was dependent on lipid rafts because pretreatment of cells with the raft-disrupting agents, methyl-β-cyclodextrin, filipin, or bacterial sphingomyelinase, reduced alkylphospholipid uptake and/or apoptosis induction and alleviated the inhibition of phosphatidylcholine synthesis. Uptake of all alkylphospholipids was inhibited by small interfering RNA (siRNA)–mediated blockage of sphingomyelin synthase (SMS1), which was previously shown to block raft-dependent endocytosis. Similar to edelfosine, perifosine accumulated in (isolated) lipid rafts independent on raft sphingomyelin content per se. However, perifosine was more susceptible than edelfosine to back-extraction by fatty acid-free serum albumin, suggesting a more peripheral location in the cell due to less effective internalization. Overall, our results suggest that lipid rafts are critical membrane portals for cellular entry of alkylphospholipids depending on SMS1 activity and, therefore, are potential targets for alkylphospholipid anticancer therapy. [Mol Cancer Ther 2007;6(8):2337–45]