Objective: To establish the patient derived xenograft (PDX) model of pseudomyxoma peritonei (PMP), and identify the key characteristics of tumor biology of this model, in order to provide a reliable model for studying the pathological mechanisms and new therapeutic strategies of PMP. Methods: PMP tumor tissue was obtained from surgery and cut into pieces after washing. Then tumor pieces were implanted subcutaneously in BAL B/c-nu mice for 6 stable passages. In the 7th passage, tumor tissue was implanted orthotopically into abdomen. Subcutaneous tumor and orthotopic tumor were then homogenized to make tumor cell suspension, implanted into abdomen of 10 BAL B/c-nu mice through midline laparotomy, 100 μl for each. The key experimental parameters including body weight changes in the observation period, experimental peritoneal cancer index (ePCI) score at the autopsy, histopathological and immunohistochemical characteristics, and gene expression profiles by high-throughput whole-genome exon sequencing were detected and recorded. Results: The successful rate of established orthotopic PDX model of human PMP was 100% (10/10). The animals showed smooth body weight increases after tumor inoculation until day 27, then the body weight began to decrease steadily. Widespread tumor dissemination of PMP tumor through the whole abdomen was found by autopsy, including the diaphragm, liver, spleen, stomach, kidney, parietal peritoneum, bowel and mesenterium. Gelatinous ascites was also observed in abdominopelvic cavity. The ePCI score ranged from 5 to 9, with a 8 of median ePCI. Histopathological studies showed peritoneal mucinous carcinomatosis accompanied with signet ring cells (PMCA-S), obvious tumor cell atypia and parenchymal invasion.Immunohistochemistry showed the expressions of MUC1, MUC2, MUC5AC, CEA, CA199, CK20, CDX-2 and Ki-67 were positive, MUC6, CK7 and p53 were negative. Whole-exome sequencing identified that the most significant genetic alteration is the exon10 missense mutation c. 1621A>C of KIT gene, the mutation abundance was 89.7%. Conclusion: PDX model of PMCA-S is successfully established, which displays the characters of high-degree malignancy, high proliferation and strong aggressiveness.
目的： 建立腹膜假黏液瘤(PMP)原位人源异种移植(PDX)模型，鉴定模型的生物学性状，为系统研究PMP病理机制、发展治疗新策略提供实验平台。 方法： 将术中获取的PMP肿瘤标本清洗切块后接种于BAL B/c－nu小鼠皮下，进行6次传代稳定后，第7次传代开腹种植于裸小鼠腹腔，将皮下瘤和腹腔原位肿瘤混合匀浆化制成瘤细胞悬液，按100 μl/只接种于10只BALB/c－nu小鼠，建立PMP的PDX模型。测量裸小鼠体重变化、实验性腹膜癌指数(ePCI)评分判断腹腔肿瘤播散程度，分析肿瘤病理学特点，全外显子高通量测序鉴定模型的关键基因表达。 结果： 模型制作成功率为100%(10/10)，接种后荷瘤动物体重平稳增加，第27天起体重持续下降。解剖见肿瘤累及盆腹腔大多数脏器，包括膈肌、肝、脾、胃、肾、壁腹膜、肠及肠系膜，盆腹腔可见少量黏液性腹水，中位ePCI为8分。常规组织病理学检查显示，腹膜高级别黏液癌伴印戒细胞，癌细胞异型性显著，侵犯脏器实质。免疫组化染色显示，MUC1、MUC2、MUC5AC、CEA、CA199、CK20、CDX－2、Ki－67均阳性，MUC6、CK7、p53均阴性。全外显子组测序显示，最主要的基因突变为KIT基因外显子10发生错义突变c.1621A>C，突变丰度达89.7%。 结论： 成功建立腹膜高级别黏液癌伴印戒细胞的PDX模型，该模型具备恶性程度高、生长速度快、侵袭性较强的生物学特征。.
Keywords: KIT mutation; Patient derived xenograft model; Pseudomyxoma peritonei; Tumor biology; Whole-genome exon sequencing.