Development of a Novel Orthotopic Gastric Cancer Mouse Model

Abstract

Background Gastric cancer metastasis is a highly fatal disease with a five-year survival rate of less than 5%. One major obstacle in studying gastric cancer metastasis is the lack of faithful models available. The cancer xenograft mouse models are widely used to elucidate the mechanisms of cancer development and progression. Current procedures for creating cancer xenografts include both heterotopic (i.e., subcutaneous) and orthotopic transplantation methods. Compared to the heterotopic model, the orthotopic model has been shown to be the more clinically relevant design as it enables the development of cancer metastasis. Although there are several methods in use to develop the orthotopic gastric cancer model, there is not a model which uses various types of tumor materials, such as soft tissues, semi-liquid tissues, or culture derivatives, due to the technical challenges. Thus, developing the applicable orthotopic model which can utilize various tumor materials is essential. Results To overcome the known limitations of the current orthotopic gastric cancer models, such as exposure of tumor fragments to the neighboring organs or only using firm tissues for the orthotopic implantation, we have developed a new method allowing for the complete insertion of soft tissue fragments or homogeneously minced tissues into the stomach submucosa layer of the immunodeficient NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG) mouse. With this completely-closed transplantation method, tumors with various types of tissue may be used to establish orthotopic gastric cancer models without the risks of exposure to nearby organs or cell leakage. This surgical procedure was highly reproducible in generating forty-eight mouse models with a surgery success rate of 96% and tumor formation of 93%. Among four orthotopic patient-derived xenograft (PDX) models that we generated in this study, we verified that the occurrence of organotropic metastasis in either the liver or peritoneal cavity was the same as that of the donor patients. Conclusion Here we describe a new protocol, step by step, for the establishment of orthotopic xenograft of gastric cancer. This novel technique will be able to increase the use of orthotopic models in broader applications for not only gastric cancer research but also any research related to the stomach microenvironment.

A β-Galactosidase-Activated Fluorogenic Reporter for the Detection of Gastric Cancer In Vivo and in Urine

“…The ability of FGCR for real-time NIRF imaging of GC was evaluated in a murine orthotopic gastric tumor model, which was established according to previous studies. 53 Briefly, mice were completely anesthetized, and the abdominal cavity was opened to expose their stomachs. A mixture of cultured GC MKN45 cells and stromal gel was injected under the gastric plasma membrane layer, followed by closing of the abdominal cavity.…”

“…The ability of FGCR for real-time NIRF imaging of GC was evaluated in a murine orthotopic gastric tumor model, which was established according to previous studies . Briefly, mice were completely anesthetized, and the abdominal cavity was opened to expose their stomachs.…”

Molecular and Immune Profiling of Syngeneic Mouse Models Predict Response to Immune Checkpoint Inhibitors in Gastric Cancer

“…Second, we established subcutaneous models, but they could not precisely reflect natural course of gastric cancer like the metastasis into the peritoneum and the liver. The orthotopic models for gastric cancer were rarely reported because it was hard to inject the cells into the gastric wall without the leakage into the gastric lumen or the peritoneum [ 32 , 33 ]. Further experiments would be needed to unravel the different res-ponses to various ICIs in gastric cancer.…”

Near-infrared fluorophores methylene blue for targeted imaging of the stomach in intraoperative navigation

“…To establish a subcutaneous gastric tumor model, 1 × 10 7 BGC-823 cells suspended in 200 μL of saline/Matrigel were inoculated subcutaneously at the left flank of the male nude mice. Furthermore, to establish an orthotopic gastric tumor model, we maintained the nude mice under anesthesia and opened the abdomen of the nude mice, and then injected 1 × 10 7 BGC-823 cells suspended in 100 μL of saline/Matrigel directly between the submucosa and the muscular layer of the stomach, finally sutured the wound according to the previous method ( Kang et al, 2021 ). When the long axis of the tumor diameter arrived at 1–2 cm or palpation of abdominal nodules, MB (250 µM/100 µL) in saline containing 10% BSA was injected into tumor-bearing mice through the tail vein.…”