👤 Andreas Herrmann

Circulating tumor cells (CTCs) drive metastasis, the leading cause of death in individuals with breast cancer. Due to their low abundance in the circulation, robust CTC expansion protocols are urgently needed to effectively study disease progression and therapy responses. Here we present the establishment of long-term CTC-derived organoids from female individuals with metastatic breast cancer. Multiomics analysis of CTC-derived organoids along with preclinical modeling with xenografts identified neuregulin 1 (NRG1)-ERBB2 receptor tyrosine kinase 3 (ERBB3/HER3) signaling as a key pathway required for CTC survival, growth and dissemination. Genome-wide CRISPR activation screens revealed that fibroblast growth factor receptor 1 (FGFR1) signaling serves a compensatory function to the NRG1-HER3 axis and rescues NRG1 deficiency in CTCs. Conversely, NRG1-HER3 activation induced resistance to FGFR1 inhibition, whereas combinatorial blockade impaired CTC growth. The dynamic interplay between NRG1-HER3 and FGFR1 signaling reveals the molecular basis of cancer cell plasticity and clinically relevant strategies to target it. Our CTC organoid platform enables the identification and validation of patient-specific vulnerabilities and represents an innovative tool for precision medicine. Show less

Oscillating gene expression is crucial for correct timing and progression through cell cycle. In Saccharomyces cerevisiae, G1 cyclins Cln1-3 are essential drivers of the cell cycle and have an important role for temporal fine-tuning. We measured time-resolved transcriptome-wide gene expression for wild type and cyclin single and double knockouts over cell cycle with and without osmotic stress. Clustering of expression profiles, peak time detection of oscillating genes, integration with transcription factor network dynamics, and assignment to cell cycle phases allowed us to quantify the effect of genetic or stress perturbations on the duration of cell cycle phases. Cln1 and Cln2 showed functional differences, especially affecting later phases. Deletion of Cln3 led to a delay of START followed by normal progression through later phases. Our data and network analysis suggest mutual effects of cyclins with the transcriptional regulators SBF and MBF. Show less

Neuronal ceroid lipofuscinoses (NCL) are a heterogeneous group of neurodegenerative diseases with mostly autosomal recessive inheritance whose common feature is the intralysosomal accumulation of ceroid lipofuscin. With varying manifestation ages the diseases result in cognitive and motor deterioration, epilepsy, diffuse retinal degeneration, and eventually death. Juvenile ceroid lipofuscinosis (JNCL, CLN3, Batten disease) has the distinctive feature that the ophthalmologic symptoms precede the neurologic symptoms by several years, and thus the ophthalmologist plays a central role in early diagnosis. Important clinical signs of JNCL include bull's eye maculopathy, severely reduced Ganzfeld ERG already at initial presentation, and unusually rapid progression of the functional decline. If JNCL is clinically suspected the diagnosis can be made by means of a standard blood smear and confirmed by genetic detection of the mutation. Although causal therapeutic options are currently only in the developmental stage, early diagnosis by the ophthalmologist is of utmost importance to allow for medical and educational support of the affected child and for adequate counseling of the parents. Show less

Peroxisome proliferator-activated receptor (PPAR)gamma is a key regulator in adipose tissue. The rare variant Pro12Ala of PPARgamma2 is associated with a decreased risk of insulin resistance. Being dietary PPARgamma ligands, conjugated linoleic acids (CLAs) received considerable attention because of their effects on body composition, cancer, atherosclerosis, diabetes, obesity and inflammation, although some effects were only demonstrated in animal trials and the results in human studies were not always consistent. In the present study effects of CLA supplementation on genome wide gene expression in adipose tissue biopsies from 11 Ala12Ala and 23 Pro12Pro men were investigated. Subjects underwent four intervention periods (4 wk) in a randomized double blind cross-over design receiving 4.25 g/d of either cis-9, trans-11 CLA, trans-10,cis-12 CLA, 1:1 mixture of both isomers or a reference linoleic acid oil preparation. After each intervention biopsies were taken, whole genome expression microarrays were applied, and genes of interest were verified by realtime PCR. The following genes of lipid metabolism were regulated by CLA: LDLR, FASN, SCD, FADS1 and UCP2 were induced, while ABCA1, CD36 and CA3 were repressed. Transcription factors PPARgamma, NFAT5, CREB5 and EBF1, the adipokine NAMPT, members of the insulin signaling cascade SORBS1 and IGF1 and IL6ST were repressed, while the adipokine THBS1 and GLUT4 involved in insulin signaling were induced. Compared to trans-10,cis-12 CLA and the CLA mixture the cis-9, trans-11 CLA isomer exerted weaker effects. Only CD36 (-1.2 fold) and THBS1 (1.5 fold) were regulated. The CLA effect on expression of PPARgamma and leptin genes depends on the PPARgamma2 genotype. The data suggest that the isomer specific influence of CLA on glucose and lipid metabolism is genotype dependent and at least in part mediated by PPARgamma. http://www.controlled-trials.com: ISRCTN91188075. Show less

The neuronal ceroidlipofuscinoses (NCL) are a group of neurodegenerative disorders and are the most common lysosomal storage diseases of infancy and childhood. Juvenile NCL is caused by CLN3 mutation, producing retinal degeneration, uncontrollable seizures, cognitive and motor decline, and early death before the age of 30 years. To study the pathogenetic mechanisms of the disease, Cln3 knock-in mice (Cln3(Deltaex7/8)) have been generated, which reproduce the 1.02-kb deletion in the CLN3 gene observed in more than 85% of juvenile NCL patients. To characterize the impact of the common Cln3 mutation on development of autofluorescent storage material, gliosis, glucose metabolism, oxidative stress, and transmitter receptors during postnatal brain maturation, brain tissue of Cln3(Deltaex7/8) mice at the ages of 3, 4, 5, 6, 9, and 19 months was subjected to immunocytochemistry to label gliotic markers and nitric oxide synthases; photometric assays to assess enzyme activities of glycolysis and antioxidative defense systems; and level of reactive nitrogen species as well as quantitative receptor autoradiography to detect select cholinergic, glutamatergic, and GABAergic receptor subtypes. The developmental increase in cerebral cortical autofluorescent lipofuscin-like deposition is accompanied by a significant astro- and microgliosis, increased activities of lactate dehydrogenase and phosphofructokinase, decreased level of glutathione peroxidase, enhanced amount of reactive nitrogen species, and lowered binding levels of N-methyl-D-aspartate- and M1-muscarinic acetylcholine receptors in select brain regions but hardly in GABA(A) receptor sites compared with wild-type mice. Detailed elucidation of the sequence of pathological events during postnatal development highlights new potential strategies for symptomatic treatment of the disease. Show less

Splicing processes might play a major role in carcinogenesis and tumour progression. The Wnt pathway is of crucial relevance for cancer progression. Therefore we focussed on the Wnt/beta-catenin signalling pathway in order to validate the expression of sequences predicted as alternatively spliced by bioinformatic methods. Splice variants of its key molecules were selected, which may be critical components for the understanding of colorectal tumour progression and may have the potential to act as biological markers. For some of the Wnt pathway genes the existence of splice variants was either proposed (e.g. beta-Catenin and CTNNB1) or described only in non-colon tissues (e.g. GSK3beta) or hitherto not published (e.g. LRP5). Both splice variants--normal and alternative form--of all selected Wnt pathway components were found to be expressed in cell lines as well as in samples derived from tumour, normal and healthy tissues. All splice positions corresponded totally with the bioinformatical prediction as shown by sequencing. Two hitherto not described alternative splice forms (CTNNB1 and LRP5) were detected. Although the underlying EST data used for the bioinformatic analysis suggested a tumour-specific expression neither a qualitative nor a significant quantitative difference between the expression in tumour and healthy tissues was detected. Axin-1 expression was reduced in later stages and in samples from carcinomas forming distant metastases. We were first to describe that splice forms of crucial genes of the Wnt-pathway are expressed in human colorectal tissue. Newly described splicefoms were found for beta-Catenin, LRP5, GSK3beta, Axin-1 and CtBP1. However, the predicted cancer specificity suggested by the origin of the underlying ESTs was neither qualitatively nor significant quantitatively confirmed. That let us to conclude that EST sequence data can give adequate hints for the existence of alternative splicing in tumour tissues. That no difference in the expression of these splice forms between cancerous tissues and normal mucosa was found, may indicate that the existence of different splice forms is of less significance for cancer formation as suggested by the available EST data. The currently available EST source is still insufficient to clearly deduce colon cancer specificity. More EST data from colon (tumour and healthy) is required to make reliable predictions. Show less

Mitogen-activated protein (MAP) kinase phosphatases (MKPs) constitute a growing family of dual specificity phosphatases, which dephosphorylate both serine/threonine and tyrosine residues of MAP kinases. MAP kinase signaling cascades are involved in the control of cell proliferation, differentiation and apoptosis. In mammals, ten members of the dual-specificity MKP family have so far been identified. In this report, we describe the cloning and expression analysis of the mouse Mkp3 gene. During early development, expression of Mkp3 is most prominent in the primitive streak, presomitic mesoderm and somites, frontonasal prominence, midbrain/hindbrain boundary, branchial arches and limb buds. At later stages, expression is also detected in the tooth primordia, vibrissae, hair follicles, pinna, submandibular gland, mammary gland primordia, lung and kidney. Strong expression was detected in the adult brain. Show less