The Construction And Application Of Human-derived Hepatocellular Carcinoma Orthotopic Xenograft

Hepatocellular carcinoma(HCC) is a world-wide health problem. The cases that patients die from HCC every year far outnumber most other cancer-related deaths. It is reported that due to the prevalence of Hepatitis B Virus(HBV), the number of newly developed HCC patients each year is extremely large in China and other parts of East Asia. However, the mechanism of how liver undergo the transformation chain from Hepatitis B to HCC after HBV infection remains unclear.Animal model remains to be the most powerful method to study the development of special diseases. In order to study the mechanism of HCC, we need to construct an appropriate animal model. However, the most popular method of constructing HCC animal model by using cancer cell lines has its defects. As cancer cell lines have already adapted to the condition of in vitro culture and passage, they might lose some of the characteristics of clinical HCC, which makes the animal model impossible to reflect the state of clinical patients. We carefully reviewed the work of former researchers and finally determined to use clinical HCC tumor tissue to directly construct patient-derived xenograft(PDX) model in immunodeficient mice. As a result, we successfully constructed orthotopic xenograft model, which could be used in proof-of-principle studies, drug screening and development of new treatment methods.Our study is focus on the construction and application of orthotopic HCC PDX model.Firstly, we collected fresh patient tumor tissues and subcutaneously inject them into NOD-SCID mice. We harvested those tumor tissues that can grow subcutaneously in mice within four months. Then, we subcutaneously inject these tumor tissues in two generations of successive NOD-SCID mice, after which we harvested tissues and try orthotopic implantation in NOD-SCID mice. In the mean time, we identified the resemblances between tumor tissue we harvested from xenograft and that from the patient. The results indicates that we successfully constructed HCC PDX model in mice and that the model shared high tissue similarity with the original patient tissue.As the characteristics of the model remained stable among generations, we studied the application in drug screening and cancer immunotherapy of the model. Firstly, we used Sorafenib (40mg/kg daily) in orthotopic PDX mice three weeks after intrahepatic transplantation and found out that three-week treatment of Sorafenib can significantly suppress tumor growth in mice.As immunotherapy of cancer has gained increasing popularity in cancer research, we tried Natural Killer(NK) cell lines NK92 and NKG respectively to explore whether NK cells could be a potential method in HCC treatment. After eight times of NK cell treatment (1×107cells/mice, three times a week), we found out that NK92 appeared to have effects on suppressing tumor growth while NKG didn't show significant effects.Thus, the xenograft model we constructed provides a trustworthy platform for drug screening, tests of drug efficacy and explorations of new methods of HCC treatment.