e13649 Background: The survival of patients with esophageal squamous cell carcinoma depends not only on clinical signs (TNM, tumor site), but also on the molecular genetic subtype of the tumor. Identification of the molecular genetic subtype and the presence/absence of clinically significant mutations is an important step towards finding new effective drugs and choosing the most appropriate therapeutic strategies. A patient-derived xenograft (PDX) model is a valuable resource to solving the problem, provided that the model accurately reproduces the basic clinical and molecular genetic characteristics of a human tumor. Our purpose was to create a PDX model of a human tumor and to study 7 polymorphisms of the xenograft tissue and tissues of a donor tumor. Methods: PDX models of esophageal cancer were produced by transplanting a tumor fragment from a patient with esophageal squamous cell carcinoma to the BALB/c Nude athymic mice (n = 10 for one PDX generation). 5 PDX were generated. 7 polymorphisms (NFE2L2 (c.85G > A), NOTCH1 (c.1379C > T), NOTCH1 (c.1451G > T), ZNF750 (c.414C > A), ZNF750 (c.1621G > A), SMARCA4 (c.2272C > T), KMT2D (c.15508C > T)) were determined by the HRM analysis in tissues of each PDX generation and in the donor tumor. Results: All examined samples demonstrated the absence of ZNF750 (c.1621G > A) and NOTCH1 (c.1379C > T) polymorphisms and the presence of ZNF750 (c.414C > A), SMARCA4 (c.2272C > T) and KMT2D (c.15508C > T) polymorphisms. Polymorphisms in the NFE2L2 (c.85G > A) gene and in the NOTCH1 (c.1451G > T) gene were found in the F3, F4 and F5 PDX generations, but were absent in the donor tumor and the F1 and F2 generations. Conclusions: Molecular and genetic characteristics of the donor tumor change through several PDX generations. Early PDX generations are recommended for the studies as they better reproduce molecular and genetic characteristics of the original tumors.
e13648 Background: Patient-derived tumor xenograft (PDX) models are a valuable resource for studying cancer biology and antitumor drug evaluation. The suitability of tumor models in vivo depends on how accurately they mimic a human disease and reproduce the histotype and molecular genetic features of a human tumor. The purpose of the study was to create a PDX model of human cancer and analyze its characteristics. Methods: PDX models of esophageal cancer were obtained by transplanting a tumor fragment from a patient with esophageal squamous cell carcinoma to the BALB/c Nude athymic mice (n = 10 for one PDX generation). Preservation of the tumor histotype was confirmed histologically (hematoxylin and eosin staining). 5 PDX were generated. An analysis of the relative copy number of the YAP1 and KDM6A genes (Real-Time qPCR) in xenograft and donor tumor tissues was performed in each generation. Results: A decrease in the copy numbers of the YAP1 and KDM6A genes by 3.8 and 2.2 times, respectively, was observed in PDX tumor samples (F3 generation) compared to normal donor tissues (p < 0.05). This trend maintained in F4 and F5 generation PDX samples. No changes in the copy numbers of the YAP1 and KDM6A genes were detected in PDX tumor samples in F1 and F2 generations. A cluster analysis (Hierarchical Clustering, Euclidean distance) demonstrated that samples of the first and second generations of esophageal cancer PDX models were closest to the patient tumor tissues in gene copy numbers. Conclusions: Later generations of esophageal cancer PDX models are characterized by changes in the genes copy numbers due to changes in the tumor and clonal selection. Early PDX generations better reproduce genetic, molecular and morphological features of tumors.
e15619 Background: Esophageal cancer is a common tumor of the mucous layer of the esophagus and the sixth most common cause of cancer deaths worldwide. Studying the mechanisms of its occurrence and development and the search for new approaches to its prevention and treatment are relevant. Such studies require a reliable experimental basis with such an important component as the use of animal models of cancer. In vivo models are an important tool both for testing new drugs and for studying the mechanisms of disease development. The purpose of the study was to create a patient-derived xenograft (PDX) model of esophageal cancer and to evaluate the proliferative activity of cells in the donor tumor and in xenograft samples in a series of successive generations. Methods: A PDX model of esophageal cancer was created by transplanting a tumor fragment from a patient with esophageal squamous cell carcinoma to the distal esophagus of BALB/c Nude athymic mice. The tumor histotype was confirmed histologically (hematoxylin and eosin staining). The proliferative activity of cells was evaluated by immunohistochemistry (IHC) with anti-Ki-67 antibodies. Results: Histological identity of xenograft samples and the donor tumor was confirmed. IHC showed an increase in the proliferative activity index in samples of transplanted tumors compared to the donor material: 12.4% in the primary tumor and 58%, 65.2%, 54.2% and 60.7% in generations 1, 3, 4 and 5, respectively. Conclusions: Histological characteristics of the donor tumor are preserved in all PDX models. The study demonstrated an increase of the proliferative activity in the first PDX generation compared to the primary tumor which persisted in the subsequent models.
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