ABSTRACT
BACKGROUND: Head and neck cancer (HNC) patients have a high risk of developing malnutrition. This randomized study aimed to compare the effect of weekly cisplatin or cetuximab combined with radiotherapy on weight loss at 3 months after treatment was started. Secondary outcomes were the prevalence of malnutrition using the Global Leadership Initiative on Malnutrition (GLIM) criteria, feeding tube dependence and health related quality of life from a nutritional perspective. METHODS: Patients from the ARTSCAN III study with advanced HNC were assessed for weight, body composition, enteral tube dependence and selected quality-of-life scores (EORTC QLQ-C30 and QLQ-H&N35) at diagnosis and 6 weeks 3, 6 and 12 months after treatment initiation. RESULTS: Of the 80 patients, 38 and 42 were randomized to receive cetuximab and cisplatin treatment, respectively. There was no significant difference in weight loss at 3 months between the two study groups. However, the cetuximab group had significantly less weight loss, fewer enteral feeding tubes and better physical functioning at the end of treatment but more pain-related problems 3 months after treatment initiation. No differences between the groups were found at 6 and 12 months. The prevalence of malnutrition was not significantly different at any time point. CONCLUSION: The hypothesized benefit of concomitant treatment with cetuximab over cisplatin regarding the prevalence of malnutrition was not supported by this study.
Subject(s)
Head and Neck Neoplasms , Malnutrition , Humans , Cetuximab/adverse effects , Cisplatin/adverse effects , Quality of Life , Head and Neck Neoplasms/drug therapy , Head and Neck Neoplasms/radiotherapy , Malnutrition/epidemiology , Malnutrition/etiology , Weight LossABSTRACT
gamma-Secretase is a key enzyme involved in the processing of the beta-amyloid precursor protein into amyloid beta-peptides (Abeta). Abeta accumulates and forms plaques in Alzheimer's disease (AD) brains. A progressive neurodegeneration and cognitive decline occurs during the course of the disease, and Abeta is believed to be central for the molecular pathogenesis of AD. Apoptosis has been implicated as one of the mechanisms behind the neuronal cell loss seen in AD. We have studied preservation and activity of the gamma-secretase complex during apoptosis in neuroblastoma cells (SH-SY5Y) exposed to staurosporine (STS). We report that the known components (presenilin, Nicastrin, Aph-1 and Pen-2) interact and form active gamma-secretase complexes in apoptotic cells. In addition, the fragments corresponding to the PS1 N-terminal fragment and the caspase-cleaved PS1 C-terminal fragment (PS1-caspCTF) were found to form active gamma-secretase complexes when co-expressed in presenilin (PS) knockout cells. Interestingly, PS1-caspCTF replaced the normal PS1 C-terminal fragment and was co-immunoprecipitated with the gamma-secretase complex in SH-SY5Y cells exposed to STS. In addition, Abeta was detected in medium from apoptotic HEK APP(swe) cells. Together, the data show that gamma-secretase complexes containing PS1-caspCTF are active, and suggest that this proteolytic activity is also important in dying cells and may affect the progression of AD.
Subject(s)
Apoptosis/drug effects , Caspases/metabolism , Endopeptidases/metabolism , Membrane Proteins/metabolism , Multiprotein Complexes/metabolism , Amyloid Precursor Protein Secretases , Amyloid beta-Protein Precursor/genetics , Amyloid beta-Protein Precursor/metabolism , Aspartic Acid Endopeptidases , Blotting, Western/methods , Cell Line, Tumor , Cell Survival/drug effects , Chromatin/metabolism , Enzyme Activation/drug effects , Enzyme Inhibitors/pharmacology , Humans , Immunoprecipitation/methods , Luciferases/biosynthesis , Mutation , Neuroblastoma , Peptide Fragments , Presenilin-1 , Protein Structure, Tertiary , Staurosporine/pharmacology , Subcellular Fractions/drug effects , Tetrazolium Salts , Thiazoles , Transfection/methodsABSTRACT
Mitochondria are central in the regulation of cell death. Apart from providing the cell with ATP, mitochondria also harbor several death factors that are released upon apoptotic stimuli. Alterations in mitochondrial functions, increased oxidative stress, and neurons dying by apoptosis have been detected in Alzheimer's disease patients. These findings suggest that mitochondria may trigger the abnormal onset of neuronal cell death in Alzheimer's disease. We previously reported that presenilin 1 (PS1), which is often mutated in familial forms of Alzheimer's disease, is located in mitochondria and hypothesized that presenilin mutations may sensitize cells to apoptotic stimuli at the mitochondrial level. Presenilin forms an active gamma-secretase complex together with Nicastrin (NCT), APH-1, and PEN-2, which among other substrates cleaves the beta-amyloid precursor protein (beta-APP) generating the amyloid beta-peptide and the beta-APP intracellular domain. Here we have identified dual targeting sequences (for endoplasmic reticulum and mitochondria) in NCT and showed expression of NCT in mitochondria by immunoelectron microscopy. We also showed that NCT together with APH-1, PEN-2, and PS1 form a high molecular weight complex located in mitochondria. gamma-secretase activity in isolated mitochondria was demonstrated using C83 (alpha-secretase-cleaved C-terminal 83-residue beta-APP fragment from BD8 cells lacking presenilin and thus gamma-secretase activity) or recombinant C100-Flag (C-terminal 100-residue beta-APP fragment) as substrates. Both systems generated an APP intracellular domain, and the activity was inhibited by the gamma-secretase inhibitors l-685,458 or Compound E. This novel localization of NCT, PS1, APH-1, and PEN-2 expands the role and importance of gamma-secretase activity to mitochondria.
