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Long-term organoid culture of a small intestinal neuroendocrine tumor

ABSTRACT: 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.

PROVIDER: EGAS00001007093 | EGA |

REPOSITORIES: EGA

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Project description:Staphylococcus aureus is one of the first and most prevalent pathogens cultured from the airways of cystic fibrosis (CF) patients, which can persist there for extended periods. Airway infections in CF patients are characterized by a strong inflammatory response of highly recruited neutrophils. One killing mechanism of neutrophils is the formation of neutrophil extracellular traps (NETs), which capture and eradicate bacteria by extracellular fibers of neutrophil chromatin decorated with antimicrobial granule proteins. S. aureus secretes nuclease, which can degrade NETs. We hypothesized, that S. aureus adapts to the airways of CF patients during persistent infection by escaping from NET-mediated killing via an increase of nuclease activity. Sputum samples of CF patients with chronic S. aureus infection were visualized by confocal microscopy after immuno-fluorescence staining for NET-specific markers, S. aureus bacteria and overall DNA structures. Nuclease activity was analyzed in sequential isogenic long persisting S. aureus isolates, as confirmed by whole genome sequencing, from an individual CF patient using a FRET-based nuclease activity assay. Additionally, some of these isolates were selected and analyzed by qRT-PCR to determine the expression of nuc1 and regulators of interest. NET-killing assays were performed with clinical S. aureus isolates to evaluate killing and bacterial survival depending on nuclease activity. To confirm the role of nuclease during NET-mediated killing, a clinical isolate with low nuclease activity was transformed with a nuclease expression vector (pCM28nuc). Furthermore, two sputa from an individual CF patient were subjected to RNA-sequence analysis to evaluate the activity of nuclease in vivo. In sputa, S. aureus was associated to extracellular DNA structures. Nuclease activity in clinical S. aureus isolates increased in a time-and phenotype-dependent manner. In the clinical isolates, the expression of nuc1 was inversely correlated to the activity of agr and was independent of saeS. NET-mediated killing was significantly higher in S. aureus isolates with low compared to isolates with high nuclease activity. Importantly, transformation of the clinical isolate with low nuclease activity with pCM28nuc conferred protection against NET-mediated killing confirming the beneficial role of nuclease for protection against NETs. Also, nuclease expression in in vivo sputa was high, which underlines the important role of nuclease within the highly inflamed CF airways. In conclusion, our data show that S. aureus adapts to the neutrophil-rich environment of CF airways with increasing nuclease expression most likely to avoid NET-killing during long-term persistence.

Project description:The management of neuroendocrine tumors (NETs) is very variable, depending on many specific aspects, such as the type of tumor, spread and patient general health. Several advances have been made with the newly developed somatostatin analogues to cure this type of malignancies. Somatostain analogues such as octreotide have been used in clinic to treat patients with neuroendocrine tumors (NETs). However, the molecular mechanism leading either to successful therapy or acquired resistance to the analogues is still to large extent unclear. Patients develop drugs resistance during a long term treatment. Therefore, to identify the pivotal regulatory genes involved in the development of drug resistance is an actual challenge. We studied five human neuroendocrine tumor cell lines, CNDT2.5, KRJ1, QGP-1, NCI H720 and NCI H727. We also investigated a long-term treated CNDT2.5 by using octreotide. We performed gene expression profiling in all the human neuroendocrine cell lines. Keywords: Gene Expression profiling, treatment comparison We investigated 5 human neuroendocrine cell lines, CNDT2.5 and KRJ1, established from ileum NETs, QGP1 by a pancreatic NET, NCI H720 and NCI H727 from bronchopulmonary NETs. CNDT2.5 cell were constantly treated with 1M-BM-5M octreotide for 10 and 16 months. We isolated total RNA (Ambion, PARISM-bM-^DM-" Kit) from 5 WT cell lines and CNDT2.5 treated with octreotide (Santostatin, Novartis). Total RNA was hybridized onto the Affymetrix Human Gene 1.0 ST Array by Affymetrix Uppsala Platform, UU. SE (Uppsala, Sweden). We first wanted to verify whether the different cell lines may become reliable models to study neuroendocrine signaling pathways. The main objective of this project aimed at understanding the mechanisms by which octrotide (Sandostatin, Novartis) alter cellular growth and differentiation of CNDT2.5 cells. We therefore focused on intermediate (10 months) and long stimulation (16 months) events triggered by sandostatin, which lead variation of CNDT.2.5 cells gene expression to identify potential pivotal genes involved in the development of drug resistance in neuroendocrine cells.

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Long-term organoid culture of a small intestinal neuroendocrine tumor

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