Thomas Herrmann

Tumour response and secondary resectability of colorectal liver metastases following neoadjuvant chemotherapy with cetuximab: the CELIM randomised phase 2 trial.

BACKGROUNDnNeoadjuvant chemotherapy for unresectable colorectal liver metastases can downsize tumours for curative resection. We assessed the effectiveness of cetuximab combined with chemotherapy in this setting.nnnMETHODSnBetween Dec 2, 2004, and March 27, 2008, 114 patients were enrolled from 17 centres in Germany and Austria; three patients receiving FOLFOX6 alone were excluded from the analysis. Patients with non-resectable liver metastases (technically non-resectable or > or =5 metastases) were randomly assigned to receive cetuximab with either FOLFOX6 (oxaliplatin, fluorouracil, and folinic acid; group A) or FOLFIRI (irinotecan, fluorouracil, and folinic acid; group B). Randomisation was not blinded, and was stratified by technical resectability and number of metastases, use of PET staging, and EGFR expression status. They were assessed for response every 8 weeks by CT or MRI. A local multidisciplinary team reassessed resectability after 16 weeks, and then every 2 months up to 2 years. Patients with resectable disease were offered liver surgery within 4-6 weeks of the last treatment cycle. The primary endpoint was tumour response assessed by Response Evaluation Criteria In Solid Tumours (RECIST), analysed by modified intention to treat. A retrospective, blinded surgical review of patients with radiological images at both baseline and during treatment was done to assess objectively any changes in resectability. The study is registered with ClinicalTrials.gov, number NCT00153998.nnnFINDINGSn56 patients were randomly assigned to group A and 55 to group B. One patient in each group were excluded from the analysis of the primary endpoint because they discontinued treatment before first full dose, one patient in group B was excluded because of early pulmonary embolism. A confirmed partial or complete response was noted in 36 (68%) of 53 patients in group A, and 30 (57%) of 53 patients in group B (difference 11%, 95% CI -8 to 30; odds ratio [OR] 1.62, 0.74-3.59; p=0.23). The most frequent grade 3 and 4 toxicities were skin toxicity (15 of 54 patients in group A, and 22 of 55 patients in group B), and neutropenia (13 of 54 patients in group A and 12 of 55 patients in group B). R0 resection was done in 20 (38%) of 53 patients in group A and 16 (30%) of 53 of patients in group B. In a retrospective analysis of response by KRAS status, a partial or complete response was noted in 47 (70%) of 67 patients with KRAS wild-type tumours versus 11 (41%) of 27 patients with KRAS-mutated tumours (OR 3.42, 1.35-8.66; p=0.0080). According to the retrospective review, resectability rates increased from 32% (22 of 68 patients) at baseline to 60% (41 of 68) after chemotherapy (p<0.0001).nnnINTERPRETATIONnChemotherapy with cetuximab yields high response rates compared with historical controls, and leads to significantly increased resectability.nnnFUNDINGnMerck-Serono, Sanofi-Aventis, and Pfizer.

A New Concept of Cellular Uptake and Intracellular Trafficking of Long-Chain Fatty Acids

Fatty acids are the main structural and energy sources of the human body. Within the organism, they are presented to cells as fatty acid: albumin complexes. Dissociation from albumin represents the first step of the cellular uptake process, involving membrane proteins with high affinity for fatty acids, e.g., fatty acid translocase (FAT/CD 36) or the membrane fatty acid-binding protein (FABPpm). According to the thus created transmembrane concentration gradient, uncharged fatty acids can flip-flop from the outer leaflet across the phospholipid bilayer. At the cytosolic surface of the plasma membrane, fatty acids can associate with the cytosolic FABP (FABPc) or with caveolin-1. Caveolins are constituents of caveolae, which are proposed to serve as lipid delivery vehicles for subcellular organelles. It is not known whether protein (FABPc)- and lipid (caveolae)-mediated intracellular trafficking of fatty acids operates in conjunction, or in parallel. Channeling fatty acids to the different metabolic pathways requires activation to acyl-CoA. For this process, the family of fatty acid transport proteins (FATP 1-5/6) might be relevant because they have been shown to possess acyl-CoA synthetase activity. Their variable N-terminal signaling sequences suggest that they might be targeted to specific organelles by anchoring in the phospholipid bilayer of the different subcellular membranes. At the highly conserved cytosolic AMP-binding site of FATP, fatty acids are activated to acyl-CoA for subsequent metabolic disposition by specific organelles. Overall, fatty acid uptake represents a continuous flow involving the following: dissociation from albumin by membrane proteins with high affinity for fatty acids; passive flip-flop across the phospholipid bilayer; binding to FABPc and caveolin-1 at the cytosolic plasma membrane; and intracellular trafficking via FABPc and/or caveolae to sites of metabolic disposition. The uptake process is terminated after activation to acyl-CoA by the members of the FATP family targeted intracellularly to different organelles.

Mice with targeted disruption of the fatty acid transport protein 4 (Fatp 4, Slc27a4) gene show features of lethal restrictive dermopathy

The fatty acid transport protein family is a group of evolutionarily conserved proteins that are involved in the cellular uptake and metabolism of long and very long chain fatty acids. However, little is known about their respective physiological roles. To analyze the functional significance of fatty acid transport protein 4 (Fatp4, Slc27a4), we generated mice with a targeted disruption of the Fatp4 gene. Fatp4-null mice displayed features of a neonatally lethal restrictive dermopathy. Their skin was characterized by hyperproliferative hyperkeratosis with a disturbed epidermal barrier, a flat dermal–epidermal junction, a reduced number of pilo-sebaceous structures, and a compact dermis. The rigid skin consistency resulted in an altered body shape with facial dysmorphia, generalized joint flexion contractures, and impaired movement including suckling and breathing deficiencies. Lipid analysis demonstrated a disturbed fatty acid composition of epidermal ceramides, in particular a decrease in the C26:0 and C26:0-OH fatty acid substitutes. These findings reveal a previously unknown, essential function of Fatp4 in the formation of the epidermal barrier.

Gemcitabine and oxaliplatin with or without cetuximab in advanced biliary-tract cancer (BINGO): a randomised, open-label, non-comparative phase 2 trial

BACKGROUNDnGemcitabine plus a platinum-based agent (eg, cisplatin or oxaliplatin) is the standard of care for advanced biliary cancers. We investigated the addition of cetuximab to chemotherapy in patients with advanced biliary cancers.nnnMETHODSnIn this non-comparative, open-label, randomised phase 2 trial, we recruited patients with locally advanced (non-resectable) or metastatic cholangiocarcinoma, gallbladder carcinoma, or ampullary carcinoma and a WHO performance status of 0 or 1 from 18 hospitals across France and Germany. Eligible patients were randomly assigned (1:1) centrally with a minimisation procedure to first-line treatment with gemcitabine (1000 mg/m(2)) and oxaliplatin (100 mg/m(2)) with or without cetuximab (500 mg/m(2)), repeated every 2 weeks until disease progression or unacceptable toxicity. Randomisation was stratified by centre, primary site of disease, disease stage, and previous treatment with curative intent or adjuvant therapy. Investigators who assessed treatment response were not masked to group assignment. The primary endpoint was the proportion of patients who were progression-free at 4 months, analysed by intention to treat. This study is registered with ClinicalTrials.gov, number NCT00552149.nnnFINDINGSnBetween Oct 10, 2007, and Dec 18, 2009, 76 patients were assigned to chemotherapy plus cetuximab and 74 to chemotherapy alone. 48 (63%; 95% CI 52-74) patients assigned to chemotherapy plus cetuximab and 40 (54%; 43-65) assigned to chemotherapy alone were progression-free at 4 months. Median progression-free survival was 6·1 months (95% CI 5·1-7·6) in the chemotherapy plus cetuximab group and 5·5 months (3·7-6·6) in the chemotherapy alone group. Median overall survival was 11·0 months (9·1-13·7) in the chemotherapy plus cetuximab group and 12·4 months (8·6-16·0) in the chemotherapy alone group. The most common grade 3-4 adverse events were peripheral neuropathy (in 18 [24%] of 76 patients who received chemotherapy plus cetuximab vs ten [15%] of 68 who received chemotherapy alone), neutropenia (17 [22%] vs 11 [16%]), and increased aminotransferase concentrations (17 [22%] vs ten [15%]). 70 serious adverse events were reported in 39 (51%) of 76 patients who received chemotherapy plus cetuximab (34 events in 19 [25%] patients were treatment-related), whereas 41 serious adverse events were reported in 25 (35%) of 71 patients who received chemotherapy alone (20 events in 12 [17%] patients were treatment-related). One patient died of atypical pneumonia related to treatment in the chemotherapy alone group.nnnINTERPRETATIONnThe addition of cetuximab to gemcitabine and oxaliplatin did not seem to enhance the activity of chemotherapy in patients with advanced biliary cancer, although it was well tolerated. Gemcitabine and platinum-based combination should remain the standard treatment option.nnnFUNDINGnInstitut National du Cancer, Merck Serono.

Cellular uptake of fatty acids driven by the ER-localized acyl-CoA synthetase FATP4.

Long-chain fatty acids are important metabolites for the generation of energy and the biosynthesis of lipids. The molecular mechanism of their cellular uptake has remained controversial. The fatty acid transport protein (FATP) family has been named according to its proposed function in mediating this process at the plasma membrane. Here, we show that FATP4 is in fact localized to the endoplasmic reticulum and not the plasma membrane as reported previously. Quantitative analysis confirms the positive correlation between expression of FATP4 and uptake of fatty acids. However, this is dependent on the enzymatic activity of FATP4, catalyzing the esterification of fatty acids with CoA. Monitoring fatty acid uptake at the single-cell level demonstrates that the ER localization of FATP4 is sufficient to drive transport of fatty acids. Expression of a mitochondrial acyl-CoA synthetase also enhances fatty acid uptake, suggesting a general relevance for this mechanism. Our results imply that cellular uptake of fatty acids can be regulated by intracellular acyl-CoA synthetases. We propose that the enzyme FATP4 drives fatty acid uptake indirectly by esterification. It is not a transporter protein involved in fatty acid translocation at the plasma membrane.

Mouse fatty acid transport protein 4 (FATP4): characterization of the gene and functional assessment as a very long chain acyl-CoA synthetase.

FATP4 (SLC27A4) is a member of the fatty acid transport protein (FATP) family, a group of evolutionarily conserved proteins that are involved in cellular uptake and metabolism of long and very long chain fatty acids. We cloned and characterized the murine FATP4 gene and its cDNA. From database analysis we identified the human FATP4 genomic sequence. The FATP4 gene was assigned to mouse chromosome 2 band B, syntenic to the region 9q34 encompassing the human gene. The open reading frame was determined to be 1929 bp in length, encoding a polypeptide of 643 amino acids. Within the coding region, the exon-intron structures of the murine FATP4 gene and its human counterpart are identical, revealing a high similarity to the FATP1 gene. The overall amino acid identity between the deduced murine and human FATP4 polypeptides is 92.2%, and between the murine FATP1 and FATP4 polypeptides is 60.3%. Northern analysis showed that FATP4 mRNA was expressed most abundantly in small intestine, brain, kidney, liver, skin and heart. Transfection of FATP4 cDNA into COS1 cells resulted in a 2-fold increase in palmitoyl-CoA synthetase (C16:0) and a 5-fold increase in lignoceroyl-CoA synthetase (C24:0) activity from membrane extracts, indicating that the FATP4 gene encodes an acyl-CoA synthetase with substrate specificity biased towards very long chain fatty acids.

Translocation of long chain fatty acids across the plasma membrane - lipid rafts and fatty acid transport proteins

Translocation of long chain fatty acids across the plasma membrane is achieved by a concert of co-existing mechanisms. These lipids can passively diffuse, but transport can also be accelerated by certain membrane proteins as well as lipid rafts. Lipid rafts are dynamic assemblies of proteins and lipids, that float freely within the two dimensional matrix of the membrane bilayer. They are receiving increasing attention as devices that regulate membrane function in vivo and play an important role in membrane trafficking and signal transduction. In this review we will discuss how lipid rafts might be involved in the uptake process and how the candidate proteins for fatty acid uptake FAT/CD36 and the FATP proteins interact with these domains. We will also discuss the functional role of FATPs in general. To our understanding FATPs are indirectly involved in the translocation process across the plasma membrane by providing long chain fatty acid synthetase activity.

New concepts of cellular fatty acid uptake: role of fatty acid transport proteins and of caveolae

Efficient uptake and channelling of long-chain fatty acids (LCFA) are critical cell functions. Evidence is emerging that proteins are important mediators of LCFA-trafficking into cells and various proteins have been suggested to be involved in this process. Amongst these proteins is a family of membrane-associated proteins termed fatty acid transport proteins (FATP). So far six members of this family, designated FATP 1-6, have been characterized. FATP 1, 2 and 6 show a highly-conserved AMP-binding region that participates in the activation of very-long-chain fatty acids (VLCFA) to form their acyl-CoA derivatives. The mechanisms by which FATP mediate LCFA uptake are not well understood, but several studies provide evidence that uptake of LCFA across cellular membranes is closely linked to acyl-CoA synthetase activity. It is proposed that FATP indirectly enhance LCFA uptake by activating VLCFA to their CoA esters, which are required to maintain the typical structure of lipid rafts in cellular membranes. Recent work has shown that the structural integrity of lipid rafts is essential for cellular LCFA uptake. This effect might be exerted by proteins, e.g. caveolin-1 and FAT/CD36, that use lipid rafts as platforms and bind or transport LCFA. The proposed molecular mechanisms await further experimental investigation.

Iron overload in adult Hfe-deficient mice independent of changes in the steady-state expression of the duodenal iron transporters DMT1 and Ireg1/ferroportin

Patients suffering from hereditary hemochromatosis (HH) show progressive iron overload as a consequence of increased duodenal iron absorption. It has been hypothesized that mutations in the HH gene HFE cause misprogramming of the duodenal enterocytes towards a paradoxical iron-deficient state, resulting in increased iron transporter expression. Previous reports concerning gene expression levels of the duodenal iron transporters DMT1 and IREG1 in HH patients and animal models are controversial, however, and in many cases only mRNA expression levels were investigated. To analyze the duodenal expression of DMT1, Ireg1, Dcytb, and hephaestin and the association with iron overload in adult Hfe−/− mice, an Hfe−/− mouse line was generated. Duodenal DMT1 and Ireg1 protein levels, duodenal DMT1, Ireg1, Dcytb, hephaestin, and TfR1 mRNA levels, and hepatic hepcidin mRNA levels were quantified and the correlation to liver iron contents was calculated. We report that duodenal DMT1 and Ireg1 mRNA levels and DMT1 and Ireg1 protein levels remained unaffected by the Hfe deletion. Furthermore, duodenal hephaestin and TfR1 mRNA expression and hepatic hepcidin mRNA expression remained unaltered, while the duodenal mRNA expression of the brush border ferric reductase Dcytb was significantly increased in Hfe−/− mice. We found no correlation between the expression level of any of the analyzed transcripts and the liver iron content. In conclusion, the lack of correlation between DMT1 and Ireg1 protein expression and the liver iron content suggests that elevated duodenal iron transporter expression is not required for high liver iron overload. Hfe−/− mice do not necessarily display features of iron deficiency in the duodenum, indicated by an increase in mRNA and protein levels of DMT1 and Ireg1. Rather, the duodenal ferric reductase Dcytb may act as a possible mediator of iron overload in Hfe deficiency.

Regulation of hepcidin in HepG2 and RINm5F cells

Despite the high impact of the antimicrobial peptide hepcidin in iron homeostasis, the regulation of this hormone is still not completely understood. Studies concerning hepcidin regulation are performed at the mRNA level. For the first time we analyzed the regulation of hepcidin not only at mRNA, but also at protein level in a hepatoma and a pancreatic beta cell line using quantitative RT-PCR and immunoblot analysis. Our data show, that hepcidin is present in HepG2 and RINm5F cells. A significant up-regulation of hepcidin was observed in both cell lines by the inflammatory cytokine interleukin-6, lipopolysaccharide, and a slight upregulation by deferoxamine. A down-regulation was detected after stimulation with erythropoietin. Hepcidin was regulated by iron in a dose dependent manner: low doses up to 3 microM increased hepcidin expression, high doses of iron (65 microM) revealed a switch-over to down-regulation of hepcidin expression. Regulation of hepcidin in HepG2 and RINm5F cells at mRNA and protein level by these substances indicates its involvement in inflammation and iron metabolism.