Project description:Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare and highly heterogeneous neoplasms whose incidence has markedly increased over the last decades. A grading system based on the tumor cells' proliferation index predicts high-risk for G3 NETs. However, low-to-intermediate grade (G1/G2) NETs have an unpredictable clinical course that varies from indolent to highly malignant. Cultures of human cancer cells enable to perform functional perturbation analyses that are instrumental to enhance our understanding of cancer biology. To date, no tractable and reliable long-term culture of G1/G2 NET has been reported to permit disease modeling and pharmacological screens. Here, we report of the first long-term culture of a G2 metastatic small intestinal NET that preserves the main genetic drivers of the tumor and retains expression patterns of the endocrine cell lineage. Replicating the tissue, this long-term culture showed a low proliferation index, and yet it could be propagated continuously without dramatic changes in the karyotype. The model was readily available for pharmacological screens using targeted agents and as expected, showed low tumorigenic capacity in vivo. Overall, this is the first long-term culture of NETs to faithfully recapitulate many aspects of the original neuroendocrine tumor.
Project description:Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare and highly heterogeneous neoplasms whose incidence has
markedly increased over the last decades. A grading system based on the tumor cells' proliferation index predicts high-risk for G3
NETs. However, low-to-intermediate grade (G1/G2) NETs have an unpredictable clinical course that varies from indolent to highly
malignant. Cultures of human cancer cells enable to perform functional perturbation analyses that are instrumental to enhance our
understanding of cancer biology. To date, no tractable and reliable long-term culture of G1/G2 NET has been reported to permit
disease modeling and pharmacological screens. Here, we report of the first long-term culture of a G2 metastatic small intestinal
NET that preserves the main genetic drivers of the tumor and retains expression patterns of the endocrine cell lineage.
Replicating the tissue, this long-term culture showed a low proliferation index, and yet it could be propagated continuously
without dramatic changes in the karyotype. The model was readily available for pharmacological screens using targeted agents
and as expected, showed low tumorigenic capacity in vivo. Overall, this is the first long-term culture of NETs to faithfully
recapitulate many aspects of the original neuroendocrine tumor.
Project description:Gastroenteropancreatic neuroendocrine tumors (GEP-NETs) are rare and highly heterogeneous neoplasms whose incidence has
markedly increased over the last decades. A grading system based on the tumor cells' proliferation index predicts high-risk for G3
NETs. However, low-to-intermediate grade (G1/G2) NETs have an unpredictable clinical course that varies from indolent to highly
malignant. Cultures of human cancer cells enable to perform functional perturbation analyses that are instrumental to enhance our
understanding of cancer biology. To date, no tractable and reliable long-term culture of G1/G2 NET has been reported to permit
disease modeling and pharmacological screens. Here, we report of the first long-term culture of a G2 metastatic small intestinal
NET that preserves the main genetic drivers of the tumor and retains expression patterns of the endocrine cell lineage.
Replicating the tissue, this long-term culture showed a low proliferation index, and yet it could be propagated continuously
without dramatic changes in the karyotype. The model was readily available for pharmacological screens using targeted agents
and as expected, showed low tumorigenic capacity in vivo. Overall, this is the first long-term culture of NETs to faithfully
recapitulate many aspects of the original neuroendocrine tumor.
Project description:Organoids retain the morphological and molecular patterns of their tissue of origin, are self-organizing, relatively simple to handle and accessible to genetic engineering. Thus, they represent an optimal tool for studying the mechanisms of tissue maintenance and aging. Long-term expansion under standard growth conditions, however, is accompanied by changes in the growth pattern and kinetics. As a potential explanation of these alterations, epigenetic drifts in organoid culture have been suggested. Here, we studied histone tri-methylation at lysine 4 (H3K4me3) and 27 (H3K27me3) and transcriptome profiles of intestinal organoids derived from mismatch repair (MMR)-deficient and control mice and cultured for 3 and 20 weeks and compared them with data on their tissue of origin. We found that, besides the expected changes in short-term culture, the organoids showed profound changes in their epigenomes also during the long-term culture. The most prominent were epigenetic gene activation by H3K4me3 recruitment to previously unmodified genes and by H3K27me3 loss from originally bivalent genes. We showed that a long-term culture is linked to broad transcriptional changes that indicate an ongoing maturation and metabolic adaptation process. This process was disturbed in MMR-deficient mice, resulting in endoplasmic reticulum (ER) stress and Wnt activation. Our results can be explained in terms of a mathematical model assuming that epigenetic changes during a long-term culture involve DNA demethylation that ceases if the metabolic adaptation is disturbed.
Project description:Organoids retain the morphological and molecular patterns of their tissue of origin, are self-organizing, relatively simple to handle and accessible to genetic engineering. Thus, they represent an optimal tool for studying mechanisms of tissue maintenance and aging. Long-term expansion under standard growth conditions, however, is accompanied by changes in growth pattern and kinetics. As a potential explanation of these alterations, epigenetic drifts in organoid culture have been suggested. Here, we study histone tri-methylation at lysine 4 (H3K4me3) and 27 (H3K27me3) and transcriptome profiles of intestinal organoids derived from mismatch repair (MMR)-deficient and control mice and cultured for 3 and 20 weeks, and compare them with data on their tissue of origin. We find that, besides the expected changes in short-term culture, organoids show profound changes in their epigenome also during long-term culture. The most prominent are epigenetic gene activation by H3K4me3 recruitment to previously unmodified genes and by H3K27me3 loss from originally bivalent genes. We show that long-term culture is linked to broad transcriptional changes that indicate an ongoing maturation and metabolic adaptation process. This process is disturbed in MMR-deficient mice, resulting in endoplasmic reticulum (ER)-stress and Wnt-activation. Our results can be explained in terms of a mathematical model assuming that epigenetic changes during long-term culture involve DNA de-methylation that ceases if the metabolic adaptation is disturbed.
Project description:We previously detected and investigated nine altered microRNAs in small intestinal neuroendocrine tumor (SI-NET) tissues at different stages of disease. The aims of this study are to: 1) analyze whether SI-NET tissue microRNAs can be also detected in patient serum samples, 2) investigate a potential somatostatin analogs (SSAs) role on microRNA levels regulation in SSA-treated patient samples and 3) elucidate whether the serum microRNA levels in samples collected in different hospitals are predictable and steady. Our results show that tissue microRNAs are detectable in patient serum samples, and miR-96, -182, -183, -196a and -200a levels are lower in SI-NET untreated patients than in SSA-treated patients at all different stages. Conversely, miR-31, -129-5p, -133a and -215 levels do not show any difference in untreated SI-NET patients and SSA-treated patients at all different stages. Our findings also show that miR-200a exhibits an atypical behavior with high levels in both untreated and SSA-treated patients at liver metastasis stage, and unequivocally never at the earlier stages. Serum samples collected in two hospitals keep alike microRNA level pattern, elucidating that the results are not dependent on samples handling. In conclusion, SI-NET tissue microRNAs are always detectable in untreated and SSA-treated patient serum samples, SSAs play an unknown role in eliciting SSA-treated patients' microRNA levels higher than in untreated patients, and this study enlightens that miR-200a might be involved in the liver metastasis during SI-NET progression.
Project description:BackgroundSmall intestinal neuroendocrine tumors (SI-NET) are highly differentiated and genetically stable malignant tumors, yet they often present with advanced metastatic spread at the time of diagnosis. In contrast to many other types of malignant tumors, primary SI-NET are often asymptomatic and typically smaller in size compared to adjacent lymph node metastases. This study explores the hypothesis that stimulating the chemosensing olfactory receptor 51E1 (OR51E1) decreases SI-NET proliferation suggesting a mechanism that explains a difference in proliferative rate based on tumor location.MethodsClinical data was used to address difference in tumor size depending on location. A SI-NET tissue microarray was used to evaluate expression of OR51E1 and olfactory marker protein (OMP). Primary cultured tumor cells from 5 patients were utilized to determine the effect of OR51E1 agonist nonanoic acid on metabolic activity. The SI-NET cell line GOT1 was used to determine effects of nonanoic acid on the transcriptome as well as long-term effects of nonanoic acid exposure with regards to cell proliferation, serotonin secretion, alterations of the cell-cycle and morphology.ResultsTumor size differed significantly based on location. OR51E1 and OMP were generally expressed in SI-NET. Primary SI-NET cells responded to nonanoic acid with a dose dependent altered metabolic activity and this was replicated in the GOT1 cell line but not in the MCF10A control cell line. Nonanoic acid treatment in GOT1 cells upregulated transcripts related to neuroendocrine differentiation and hormone secretion. Long-term nonanoic acid treatment of GOT1 cells decreased proliferation, induced senescence, and altered cell morphology.ConclusionOur results raise the possibility that exposure of intraluminal metabolites could represent a mechanism determining aspects of the SI-NET tumor phenotype. However, we could not causally link the observed effects of nonanoic acid exposure to the OR51E1 receptor.
Project description:SKM-1 cells were cultured for 28 days in the absence or presence of low doses of the DNMT1 inhibitors DAC (10 nM) or AZA (100 nM). The experiment was carried in two independent set at different times, and with 2 replicates for each condition (Ctl, AZA, DAC) for a total of 12 samples. The SKM-1 cell line is derived from secondary AML arising from MDS, and is one the few representative in vitro models of MDS.
Project description:Small intestinal neuroendocrine tumors (SI-NETs) are small, slow growing neoplasms with loss of one copy of chromosome 18 as a common event. Frequently mutated genes on chromosome 18 or elsewhere have not been found so far. The aim of this study was to investigate a possible tumor suppressor role of the transmembrane receptor type tyrosine phosphatase PTPµ (PTPRM at 18p11) in SI-NETs. Immunohistochemistry, quantitative RT-PCR, colony formation assay and quantitative CpG methylation analysis by pyrosequencing were performed. Undetectable/very low levels of PTPRM or aberrant pattern of immunostaining, with both negative and positive areas, were detected in the majority of tumors (33/40), and a significantly reduced mRNA expression in metastases compared to primary tumors was observed. Both the DNA methylation inhibitor 5-aza-2'-deoxycytidine and the S-adenosylhomocysteine hydrolase inhibitor 3-deazaneplanocin A (DZNep) induced PTPRM expression in CNDT2.5 and KRJ-I SI-NET cells. CpG methylation of upstream regulatory regions, the promoter region and the exon 1/intron 1 boundary was detected by pyrosequencing analysis of the two cell lines and not in the analyzed SI-NETs. Overexpression of PTPRM in the SI-NET cell lines reduced cell growth and cell proliferation and induced apoptosis. The tyrosine phosphatase activity of PTPRM was not involved in cell growth inhibition. The results support a role for PTPRM as a dysregulated candidate tumor suppressor gene in SI-NETs and further analyses of the involved mechanisms are warranted.