Martin Schneider

Universität Heidelberg, Heidelburg, Baden-Württemberg, Germany

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Publications (40)314.26 Total impact

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    ABSTRACT: Within primary colorectal cancer (CRC) a sub-fraction of all tumor-initiating cells (TIC) drives long-term progression in serial xenotransplantation. It has been postulated that efficient maintenance of TIC activity in vitro requires serum-free spheroid culture conditions that support a stem-like state of CRC cells. To address whether tumorigenicity is indeed tightly linked to such a stem-like state in spheroids, we transferred TIC-enriched spheroid cultures to serum-containing adherent conditions that should favor their differentiation. Under these conditions, primary CRC cells did no longer grow as spheroids, but formed an adherent cell layer, up-regulated colon epithelial differentiation markers, and down-regulated TIC-associated markers. Strikingly, upon xenotransplantation cells cultured under either condition equally efficient formed serially transplantable tumors. Clonal analyses of individual lentivirally marked TIC clones cultured under either culture condition revealed no systematic differences in contributing clone numbers, indicating that phenotypic differentiation does not select for few individual clones adapted to unfavorable culture conditions. Our results reveal that CRC TIC can be propagated under conditions previously thought to induce their elimination. This phenotypic plasticity allows addressing primary human CRC TIC properties in experimental settings based on adherent cell growth.
    No preview · Article · Dec 2015 · Cancer letters
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    ABSTRACT: Background: Colorectal cancer is the third most common malignancy in humans and novel therapeutic approaches are urgently needed. Autophagy is an evolutionarily highly conserved cellular process by which cells collect unnecessary organelles or misfolded proteins and subsequently degrade them in vesicular structures in order to refuel cells with energy. Dysregulation of the complex autophagy signaling network has been shown to contribute to the onset and progression of cancer in various models. The Bcl-2 family of proteins comprises central regulators of apoptosis signaling and has been linked to processes involved in autophagy. The antiapoptotic members of the Bcl-2 family of proteins have been identified as promising anticancer drug targets and small molecules inhibiting those proteins are in clinical trials. Methods: Flow cytometry and colorimetric assays were used to assess cell growth and cell death. Long term 3D cell culture was used to assess autophagy in a tissue mimicking environment in vitro. RNA interference was applied to modulate autophagy signaling. Immunoblotting and q-RT PCR were used to investigate autophagy signaling. Immunohistochemistry and fluorescence microscopy were used to detect autophagosome formation and autophagy flux. Results: This study demonstrates that autophagy inhibition by obatoclax induces cell death in colorectal cancer (CRC) cells in an autophagy prone environment. Here, we demonstrate that pan-Bcl-2 inhibition by obatoclax causes a striking, late stage inhibition of autophagy in CRC cells. In contrast, ABT-737, a Mcl-1 sparing Bcl-2 inhibitor, failed to interfere with autophagy signaling. Accumulation of p62 as well as Light Chain 3 (LC3) was observed in cells treated with obatoclax. Autophagy inhibition caused by obatoclax is further augmented in stressful conditions such as starvation. Furthermore, our data demonstrate that inhibition of autophagy caused by obatoclax is independent of the essential pro-autophagy proteins Beclin-1, Atg7 and Atg12. Conclusions: The objective of this study was to dissect the contribution of Bcl-2 proteins to autophagy in CRC cells and to explore the potential of Bcl-2 inhibitors for autophagy modulation. Collectively, our data argue for a Beclin-1 independent autophagy inhibition by obatoclax. Based on this study, we recommend the concept of autophagy inhibition as therapeutic strategy for CRC.
    Full-text · Article · Dec 2015 · BMC Cancer
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    ABSTRACT: Objective: To investigate whether liver metastases contribute to metastatic spread of colorectal cancer (CRC) by shedding intact tumor cells. Background: Metastases represent the primary cause of death in CRC. Understanding the metastatic activity of metastases and which patients are at high risk for tumor cell dissemination may, therefore, have significant influence on cancer care in the future. Methods: Circulating tumor cells (CTCs) were detected in the hepatic inflow (portal venous blood [PVB]) and outflow compartment (hepatic venous blood [HVB]) of a training (n = 55) and validation (n = 50) set using the CellSearch system. Isolated CTC from the HVB were subjected to gene expression analyses by quantitative polymerase chain reaction. Results: CTC detection rate (37.2% vs 19.6%; P = 0.04) and count (mean: 12.7, SEM: ± 5.9 vs 1.9; ± 1.2; P = 0.01) were significantly higher in HVB compared to PVB. The increased CTC detection rate (54% vs 11.4%; P < 0.001) and CTC count (14.7 ± 5.1 vs 1.1 ± 0.6; P < 0.001) in the HVB compared to the PVB compartment was confirmed in the validation cohort. Expression of epithelial markers and genes involved in cell-to-cell and cell-to-matrix adhesion was reduced in CTC compared to tumor cells in liver metastases. Metastasis size greater than 5 cm was associated with CTC shedding from established liver metastases in the training and validation cohorts. Conclusions: Colorectal liver metastases shed intact tumor cells with an invasive phenotype. Metastasis size serves as a surrogate marker for metastatic activity of colorectal liver metastases.
    Full-text · Article · Oct 2015 · Annals of surgery
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    ABSTRACT: Overcoming resistance to chemotherapy is a major challenge in colorectal cancer (CRC) treatment, especially since the underlying molecular mechanisms remain unclear. We show that silencing of the prolyl hydroxylase domain protein PHD1, but not PHD2 or PHD3, prevents p53 activation upon chemotherapy in different CRC cell lines, thereby inhibiting DNA repair and favoring cell death. Mechanistically, PHD1 activity reinforces p53 binding to p38α kinase in a hydroxylation-dependent manner. Following p53-p38α interaction and chemotherapeutic damage, p53 can be phosphorylated at serine 15 and thus activated. Active p53 allows nucleotide excision repair by interacting with the DNA helicase XPB, thereby protecting from chemotherapy-induced apoptosis. In accord with this observation, PHD1 knockdown greatly sensitizes CRC to 5-FU in mice. We propose that PHD1 is part of the resistance machinery in CRC, supporting rational drug design of PHD1-specific inhibitors and their use in combination with chemotherapy. © 2015 The Authors. Published under the terms of the CC BY 4.0 license.
    Full-text · Article · Aug 2015 · EMBO Molecular Medicine
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    ABSTRACT: Background: Metabolic and transcriptomic differences between visceral adipose tissue (VAT) and subcutaneous adipose tissue (SAT) compartments, particularly in the context of obesity, may play a role in colorectal carcinogenesis. We investigated the differential functions of their metabolic compositions. Objectives: Biochemical differences between adipose tissues (VAT vs. SAT) in patients with colorectal carcinoma (CRC) were investigated by using mass spectrometry metabolomics and gene expression profiling. Metabolite compositions were compared between VAT, SAT, and serum metabolites. The relation between patients’ tumor stage and metabolic profiles was assessed. Design: Presurgery blood and paired VAT and SAT samples during tumor surgery were obtained from 59 CRC patients (tumor stages I–IV) of the ColoCare cohort. Gas chromatography time-of-flight mass spectrometry and liquid chromatography quadrupole time-of-flight mass spectrometry were used to measure 1065 metabolites in adipose tissue (333 identified compounds) and 1810 metabolites in serum (467 identified compounds). Adipose tissue gene expression was measured by using Illumina’s HumanHT-12 Expression BeadChips. Results: Compared with SAT, VAT displayed elevated markers of inflammatory lipid metabolism, free arachidonic acid, phospholipases (PLA2G10), and prostaglandin synthesis–related enzymes (PTGDS/PTGS2). Plasmalogen concentrations were lower in VAT compared with SAT, which was supported by a lower FAR1 gene expression, the rate-limiting enzyme for ether-lipid synthesis in VAT. Serum sphingomyelin concentrations were inversely correlated (P = 0.0001) with SAT adipose triglycerides. Logistic regression identified lipids in patients’ adipose tissues, which were associated with CRC tumor stage. Conclusions: As one of the first studies, we comprehensively assessed differences in metabolic, lipidomic, and transcriptomic profiles between paired human VAT and SAT and their association with CRC tumor stage. We identified markers of inflammation in VAT, which supports prior evidence regarding the role of visceral adiposity and cancer. This trial was registered at clinicaltrials.gov as NCT02328677.
    No preview · Article · Jul 2015 · American Journal of Clinical Nutrition

  • No preview · Conference Paper · Jul 2015
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    ABSTRACT: Local recurrence of rectal cancer after curative surgery predicts patients' prognosis. The correlation between the exact anatomic location of tumour recurrence and patients' survival is still under debate. Thus, this study aimed to investigate the impact of the exact location of recurrent rectal cancer on post-operative morbidity and survival. This is a retrospective study including 90 patients with locally recurrent rectal cancer. The location of tumour recurrence was classified into intraluminal and extraluminal recurrence. Univariate and multivariable Cox regression analyses were used to determine the impact on post-operative morbidity and survival. Patients' survival with intraluminal recurrence was significantly longer compared to patients with extraluminal recurrence (p = 0.027). Curative resection was associated with prolonged survival in univariate and multivariable analyses (p = 0.0001) and was more often achieved in patients with intraluminal recurrence (p = 0.024). Survival of curative resected patients with intraluminal recurrence was significantly longer compared to curatively resected patients with extraluminal recurrence (p = 0.0001). The rate of post-operative morbidity between intraluminal and extraluminal recurrence was not statistically different (p = 0.59). Based on the present investigation, intraluminal recurrence is associated with superior outcome. Post-operative morbidity did not differ significantly between both groups.
    No preview · Article · Mar 2015 · Journal of Gastrointestinal Surgery
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    ABSTRACT: Lynch syndrome is caused by germline mutations of DNA mismatch repair (MMR) genes, most frequently MLH1 and MSH2. Recently, MMR-deficient crypt foci (MMR-DCF) have been identified as a novel lesion which occurs at high frequency in the intestinal mucosa from Lynch syndrome mutation carriers, but very rarely progress to cancer. To shed light on molecular alterations and clinical associations of MMR-DCF, we systematically searched the intestinal mucosa from Lynch syndrome patients for MMR-DCF by immunohistochemistry. The identified lesions were characterised for alterations in microsatellite-bearing genes with proven or suspected role in malignant transformation. We demonstrate that the prevalence of MMR-DCF (mean 0.84 MMR-DCF per 1 cm2 mucosa in the colorectum of Lynch syndrome patients) was significantly associated with patients' age, but not with patients' gender. No MMR-DCF were detectable in the mucosa of patients with sporadic MSI-H colorectal cancer (n = 12). Microsatellite instability of at least one tested marker was detected in 89% of the MMR-DCF examined, indicating an immediate onset of microsatellite instability after MMR gene inactivation. Coding microsatellite mutations were most frequent in the genes HT001 (ASTE1) with 33%, followed by AIM2 (17%) and BAX (10%). Though MMR deficiency alone appears to be insufficient for malignant transformation, it leads to measurable microsatellite instability even in single MMR-deficient crypts. Our data indicate for the first time that the frequency of MMR-DCF increases with patients' age. Similar patterns of coding microsatellite instability in MMR-DCF and MMR-deficient cancers suggest that certain combinations of coding microsatellite mutations, including mutations of the HT001, AIM2 and BAX gene, may contribute to the progression of MMR-deficient lesions into MMR-deficient cancers.
    Full-text · Article · Mar 2015 · PLoS ONE
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    ABSTRACT: Signal transducer and activator of transcription proteins (STATs) are crucial regulators of cell growth and differentiation; however, their specific prognostic impact in human colon cancer has only been studied to limited extent. We aimed to assess the prognostic significance of specific STAT expression patterns in colon carcinoma. Protein expression patterns of activated STAT1, STAT3, STAT4, and STAT5 in human colon carcinoma tissue and corresponding healthy mucosa (n = 104) were assessed using multiplex bead-based immunoassay technologies. Expression patterns were correlated with clinical and survival data. Immunohistochemistry was performed to assess spatial expression of STAT3 and STAT5. STAT3 was underexpressed whereas STAT4 and STAT5 were overexpressed in colon carcinoma tissue. Primary tumors from patients with distant metastases (M1) displayed significantly increased expression of STAT1 and STAT3 but decreased expression of STAT4 and STAT5. Increased tumor expression of STAT1 or STAT3 was associated with impaired patient survival, whereas increased expression of STAT4 or STAT5 correlated with improved survival. Multivariate analysis identified an increased STAT3/STAT5 expressional ratio as an adverse prognostic marker in colon cancer patients. The tumor progression-associated transcription factors STAT3, STAT4, and STAT5 are differently expressed in colon carcinoma tissue and colon mucosa. Moreover, the STAT3/STAT5 expression ratio is an independent prognostic marker in colon cancer patients.
    No preview · Article · Mar 2015 · Annals of Surgical Oncology
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    ABSTRACT: Oxygen is essential for metazoans to generate energy. Upon oxygen deprivation adaptive and protective pathways are induced, mediated by hypoxia-inducible factors (HIFs) and prolyl hydroxylase domain-containing enzymes (PHDs). Both play a pivotal role in various conditions associated with prolonged ischemia and inflammation, and are promising targets for therapeutic intervention. This review focuses on aspects of therapeutic PHD modulation in surgically relevant disease conditions such as hepatic and intestinal disorders, wound healing, innate immune responses, and tumorigenesis, and discusses the therapeutic potential and challenges of PHD inhibition in surgical patients.
    Full-text · Article · Jan 2015
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    ABSTRACT: Background and Objectives Only limited data exist investigating the outcome of patients older than 75 years after resection of colorectal liver metastases (CLM). Therefore, the present study aims to evaluate clinical and oncological outcome of elderly patients.MethodsA cohort of 405 patients was divided into three age-groups: (1) <65 years; (2) 65–75 years; and (3) >75 years of age. Patients' data were prospectively collected and retrospectively analyzed. We performed survival analysis and added age-correction. Univariate and multivariate analysis was performed to determine independent prognostic risk factors.ResultsThe 5-year survival rate of the >75 years age-group was distinctly decreased, compared to the other age-groups. After age-correction, the 5-year survival rates and the survival curves increased to the greatest extent in patients older than 75 years. The MSKCC score proved to be a sufficient independent prognostic factor in the total patient cohort, patients <65 years and patients 65–75 years. In patients older than 75 years, only localization of the primary tumors was a significant prognostic factor for overall survival.Conclusions Patients' age is no reason to deny surgical treatment of CLM. Prognostic factors, such as MSKCC score, are not sufficient predictors of survival in patients older than 75 years. J. Surg. Oncol. © 2015 Wiley Periodicals, Inc.
    No preview · Article · Jan 2015 · Journal of Surgical Oncology
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    ABSTRACT: miRNAs are crucial in cellular processes and have been shown to be abnormally expressed in cancer tissue and the circulation. Circulating miRNAs may serve as a novel class of minimally invasive biomarkers for prognosis. Within a first methodologic study, we evaluated the miRNA profile kinetics in the plasma of patients with colorectal cancer after surgical tumor removal to identify potential suitability as prognostic biomarkers. This pilot study is based on the ColoCare Study, a cohort study of newly diagnosed patients with stage I-IV colorectal cancer. Colorectal cancer pre- and postsurgical blood (2-7 days after surgery) and 6 months follow-up blood from 35 patients were examined and candidate miRNAs were investigated in the plasma. miRNA levels were measured by two-step qRT-PCR. Statistical analysis was performed using log-transformed normalized CT values using SAS 9.3. Comparing pre- and post-surgical miRNA levels revealed a statistically significant decrease of nine circulating miRNAs after surgery (miR92a, miR18a, miR320a, miR106a, miR16-2, miR20a, miR223, miR17, and miR143). Analyses of plasma levels over all three time points demonstrated a statistically significant decrease from presurgery to postsurgery and re-increase from postsurgery to the six months follow-up time point of four circulating miRNAs (miR92a, miR320a, miR106a, and miR18a). We were able to show for the first time that in plasma miRNA profiles change within days after colorectal cancer surgery. Our results underscore the role of the investigated miRNAs in colorectal cancer and their potential utility as prognostic biomarkers.
    No preview · Article · Dec 2014 · Cancer Epidemiology Biomarkers & Prevention
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    ABSTRACT: Pancreatic cancer consists of a heterogenous bulk of tumor cells and stroma cells which contribute to tumor progression by releasing angiogenic factors. Those factors can be detected as circulating serum factors. We performed a compartment-specific analysis of tumor-derived and stroma-derived angiogenic factors to identify biomarkers and molecular targets for the treatment of pancreatic cancer. Kryo-frozen tissue from primary ductal adenocarcinomas (n = 51) was laser-microdissected to isolate tumor and stroma tissue. Expression of 17 angiogenic factors (angiopoietin-2, follistatin, GCSF, HGF, interleukin-8, leptin, PDGF-BB, PECAM-1, VEGF, matrix metalloproteinase -1, -2, -3, -7, -9, -10, -12, and -13) was analyzed using a multiplex elisa assay for tissue-derived proteins and corresponding serum. Our study reveals a compartment-specific expression profile for several angiogenic factors and matrix metalloproteinases. ROC analysis of corresponding serum samples reveals MMP-7 and MMP-12 as strong classifiers for the diagnosis of patients with pancreatic cancer vs. healthy control donors. High expression of tumor-derived PDGF-BB and MMP-1 correlates with prolonged survival in univariate and multivariate analysis. In conclusion, a distinct expression patterns for angiogenic cytokines and MMPs in pancreatic cancer and surrounding stroma may implicate them as novel targets for cancer treatment. Tumor-derived PDGF-BB and MMP-1 are significant and independent prognostic markers for poor survival.
    Full-text · Article · Nov 2014 · Oncotarget

  • No preview · Conference Paper · Oct 2014
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    ABSTRACT: Background: Whether anastomotic leakage (AL) has a negative impact on survival remains a matter of debate. This study aimed to assess the impact of AL on the overall and disease-free survival of patients undergoing curative resection of stages 1-3 rectal cancer using propensity-scoring methods. Methods: In a single-center study, 570 patients undergoing curative resection of stages 1-3 rectal cancer between January 2002 and December 2011 were assessed. The mean follow-up period was 4.7 ± 2.9 years. Patients who did and did not experience AL were compared using Cox regression and propensity score analyses. Results: Overall, 51 patients (8.9 %) experienced an AL. The characteristics of the patients were highly biased concerning AL (propensity score, 0.16 ± 0.12 vs. 0.09 ± 0.07; P < 0.001). Anastomotic leakage was uniformly associated with a significantly increased risk of mortality in unadjusted analysis [hazard ratio (HR) 2.30; 95 % confidence interval (CI) 1.40-3.76; P = 0.003], multivariable Cox regression (HR 2.27; 95 % CI 1.33-3.88; P = 0.005), and propensity score-adjusted Cox regression (HR 2.07; 95 % CI 1.21-3.55; P = 0.014). Similarly, disease-free survival was significantly impaired in patients who experienced AL according to unadjusted analysis (HR 1.88; 95 % CI 1.19-2.95; P = 0.011), multivariable Cox regression (HR 1.90; 95 % CI 1.17-3.09; P = 0.014), and propensity score-adjusted Cox regression (HR 2.31; 95 % CI 1.40-3.80; P = 0.002). Conclusions: This is the first propensity score-based analysis providing evidence that oncologic outcome may be impaired after curative rectal cancer resection in patients with AL.
    No preview · Article · Oct 2014 · Annals of Surgical Oncology
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    ABSTRACT: Humoral immune responses against tumor antigens are studied as indirect markers of antigen exposure and in cancer vaccine studies. An increasing number of tumor antigens potentially translated from mutant genes is identified by advances in genomic sequencing. They represent an interesting source for yet unknown immunogenic epitopes. We here describe a multiplex method using the Luminex technology allowing for the detection of antibodies against multiple in silico-predicted linear neo-antigens in large sets of sera. The approach included 32 synthetic biotinylated peptides comprising a predicted set of frameshift mutation-induced neo-antigens. The antigens were fused to a FLAG epitope to ensure monitoring antigen binding to avidin-linked microspheres in the absence of monoclonal antibodies. Analytical specificity of measured serum antibody reactivity was proven by the detection of immune responses in immunized rabbits and a colorectal cancer patient vaccinated with peptides included in the assay. The measured antibody responses were comparable to peptide ELISA, and inter-assay reproducibility of the multiplex approach was excellent (R 2 > 0.98) for 20 sera tested against all antigens. Our methodic approach represents a valuable platform to monitor antibody responses against predicted antigens. It may be used in individualized cancer vaccine studies, thereby extending the relevance beyond the model system in the presented approach.
    Full-text · Article · Aug 2014 · Cancer Immunology and Immunotherapy
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    ABSTRACT: Metastasis formation is the most common cause of colorectal cancer (CRC) related death. How cancer cells disseminate from the primary tumor, gain access to blood and lymphatic vessels and seed to distant organs is not fully understood. To gain deeper mechanistic insights into metastasis formation, we developed a metastasis xenotransplantation model for primary human colorectal cancer cells. Patient (n=12) derived tumor-initiating cells (TIC) were enriched in spheroid cultures and subsequently transplanted into the kidney capsule of immunodeficient NOD/SCID-IL2RGnull (NSG) mice. Importantly, cultures derived from 3 distinct patients frequently metastasized into the murine liver and spleen, whereas spheroids derived from all other patients (n=9) never did. Compared to non-metastasizing spheroids, metastasizing spheroids strongly expressed mesenchymal markers (e.g. Vimentin and N-cadherin), whereas epithelial and colonic differentiation markers (e.g. E-cadherin, Trefoil factor 3, Defensin alpha 5, Keratin-8, -18 -20) were down-regulated suggesting that metastasizing primary patient derived CRC spheroids may have passed through an epithelial to mesenchymal transition (EMT). As the miR-200 family has been shown to support an epithelial phenotype and has been implicated in the process of EMT in tumor cells, we analyzed miRNA expression in metastasizing versus non-metastasizing spheroid cultures. Interestingly, metastasizing spheroids strongly down-regulated the miR-200 clusters miR-200a/-200b/-429 and miR-200c/-141 as well as miR-194 and miR-203. To further understand the mechanism of deregulated gene- and miRNA expression in metastasizing spheroids, we evaluated the DNA methylation status of miRNA promoters. In contrast to non-metastasizing spheroid cultures, metastasizing spheroids showed pronounced DNA methylation within the miR-200 promoter regions, indicating that miR-200 expression in primary metastasizing human colorectal cancer spheroids is suppressed through epigenetic mechanisms. Forced overexpression of both miR-200 clusters in metastasizing spheroids restored expression of epithelial genes like E-Cadherin and Keratin-8 and reduced expression of the mesenchymal markers Vimentin and N-cadherin. Moreover, incubation with low dose 5-aza-2′-deoxycytidine increased the expression of epithelial cell adhesion molecule (EpCAM) in metastasizing spheroids, indicating a partial reversion of the mesenchymal phenotype by demethylating agents. In summary, our findings indicate that metastasizing primary human CRC spheroids are epigenetically fixed in a mesenchymal state. This model allows further dissecting and understanding mechanisms of EMT and metastasis formation in human CRC thereby providing the basis for the development of future therapeutic intervention strategies against metastasizing human colorectal cancer.
    No preview · Conference Paper · Apr 2014
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    ABSTRACT: We have previously shown that long term progression of human colorectal cancer in serial xenotransplantation is driven by a small sub-fraction of all tumor initiating cells (TIC). These long-term TIC (LT-TIC) self-renew extensively in vivo and are exclusively able to seed metastases in distant organs. Defined phenotypic surface markers of LT-TIC would be crucial to develop effective antibody-based targeting strategies. However, it remains elusive whether a fixed phenotype of long-term TIC is associated with their tumorigenicity thereby allowing prospective isolation of this most relevant cancer cell fraction. To address this question, three dimensional spheroid cultures in serum free medium supplemented with FGF and EGF were generated from primary human colon cancer specimens to enrich for TIC. To calculate the frequency of TIC in spheroid cultures, cells were transplanted in limiting dilution into cohorts of Nod/SCID-IL2RG-/- (NSG) mice. TIC frequency varied from 1 in 22 to 1 in 2x104 spheroid cells, depending on the respective patient sample. When the spheroid cells were transferred to culture conditions that favor their differentiation (gelatin coated plates in the presence of serum and withdrawal of cytokines) the phenotype changed dramatically. The primary colon cancer cells did no longer grow as spheroids but formed an adherent cell layer and up-regulated the colon epithelial differentiation markers CDX2, DEFA5, KRT80, Muc20 and TFF2. In addition, CD133, a widely used marker to enrich for TICs in various solid cancers, was strongly down-regulated upon serum treatment. Strikingly, when xenotransplantated into NSG mice, cells cultured under spheroid and differentiation conditions equally formed serially transplantable tumors, demonstrating that tumor initiating and self-renewal capacity of TIC was not restricted to phenotypically immature spheroid cells. Moreover, CD133 expression did not predict successful tumor formation in vivo. Sorted CD133+ and CD133- cells from 3 individual patients formed tumors with equal efficiency and regenerated both, CD133+ and CD133- cells in vivo. Importantly, clonal analyses of individual lentivirally marked TIC clones cultured under either culture condition revealed no systematic differences in TIC frequency, demonstrating that phenotypic differentiation does not lead to quantitative elimination of TIC clones. Our results demonstrate that phenotypic differentiation does not eliminate the tumor-initiating potential of human colorectal TIC. Moreover, expression of CD133 does not predict their tumor forming and self-renewal potential. This pronounced phenotypic plasticity of human colon cancer TIC poses a grave challenge for surface-targeted elimination of TIC in colorectal cancer.
    No preview · Conference Paper · Apr 2014
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    ABSTRACT: Abstract BACKGROUND & AIMS: Hypoxia inducible factor (HIF) prolyl hydroxylase inhibitors are protective in mouse models of inflammatory bowel disease (IBD). Here, we investigated the therapeutic target(s) and mechanism(s) involved. METHODS: The effect of genetic deletion of individual HIF-prolyl hydroxylase (PHD) enzymes on the development of dextran sulphate sodium (DSS)-induced colitis was examined in mice. RESULTS: PHD1(-/-), but not PHD2(+/-) or PHD3(-/-), mice were less susceptible to the development of colitis than wild-type controls as determined by weight loss, disease activity, colon histology, neutrophil infiltration, and cytokine expression. Reduced susceptibility of PHD1(-/-) mice to colitis was associated with increased density of colonic epithelial cells relative to wild-type controls, which was because of decreased levels of apoptosis that resulted in enhanced epithelial barrier function. Furthermore, with the use of cultured epithelial cells it was confirmed that hydroxylase inhibition reversed DSS-induced apoptosis and barrier dysfunction. Finally, PHD1 levels were increased with disease severity in intestinal tissue from patients with IBD and in colonic tissues from DSS-treated mice. CONCLUSIONS: These results imply a role for PHD1 as a positive regulator of intestinal epithelial cell apoptosis in the inflamed colon. Genetic loss of PHD1 is protective against colitis through decreased epithelial cell apoptosis and consequent enhancement of intestinal epithelial barrier function. Thus, targeted PHD1 inhibition may represent a new therapeutic approach in IBD.
    No preview · Dataset · Jul 2013
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    ABSTRACT: Tumors from colorectal cancer (CRC) are generally immunogenic and commonly infiltrated with T lymphocytes. However, the details of the adaptive immune reaction to these tumors are poorly understood. We have accrued both colon tumor samples and adjacent healthy mucosal samples from 15 CRC patients to study lymphocytes infiltrating these tissues. We apply a method for detailed sequencing of T-cell receptor (TCR) sequences from tumor-infiltrating lymphocytes (TILs) in CRC tumors at high throughput to probe T-cell clones in comparison with the TCRs from adjacent healthy mucosal tissue. In parallel, we captured TIL counts using standard immunohistochemistry. The variation in diversity of the TIL repertoire was far wider than the variation of T-cell clones in the healthy mucosa, and the oligoclonality was higher on average in the tumors. However, the diversity of the T-cell repertoire in both CRC tumors and healthy mucosa was on average 100-fold lower than in peripheral blood. Using the TCR sequences to identify and track clones between mucosal and tumor samples, we determined that the immune response in the tumor is different than in the adjacent mucosal tissue, and the number of shared clones is not dependent on distance between the samples. Together, these data imply that CRC tumors induce a specific adaptive immune response, but that this response differs widely in strength and breadth between patients.
    No preview · Article · Jun 2013 · Cancer Immunology and Immunotherapy

Publication Stats

1k Citations
314.26 Total Impact Points

Institutions

  • 2009-2015
    • Universität Heidelberg
      • • Department of General, Visceral and Transplantation Surgery
      • • Department of Spine Surgery
      Heidelburg, Baden-Württemberg, Germany
  • 2012
    • Vesalius Research Center
      Louvain, Flanders, Belgium
  • 2008
    • Imperial College London
      Londinium, England, United Kingdom
    • University of Leuven
      • Division of Gene Technology
      Louvain, Flanders, Belgium