A GFP-labeled human colon cancer metastasis model featuring surgical orthotopic implantation

The Essential Factors of Establishing Patient-derived Tumor Model

Establishing an applicable preclinical model is vital for translational cancer research. Patient-derived xenograft has been important preclinical model systems and widely used for cancer research. Patient-derived xenograft models that represent the tumors of the patients are necessary to better translate research discoveries and to test potential therapeutic approaches. However, research in this field is hampered by the limited engraftment rate. In this review, we go over a large number of researches on patient-derived xenograft transplantation and firstly systematically summarize the main factors in methodology to successfully establish models. These results will be applied to the development of patient-derived xenograft leading to better preclinical research.

Colorectal cancer models for novel drug discovery

INTRODUCTION

Despite increased screening rates and advances in targeted therapy, colorectal cancer (CRC) remains the third leading cause of cancer-related mortality. CRC models that recapitulate key features of human disease are essential to the development of novel and effective therapeutics. Classic methods of modeling CRC such as human cell lines and xenograft mice, while useful for many applications, carry significant limitations. Recently developed in vitro and in vivo models overcome some of these deficiencies and thus can be utilized to better model CRC for mechanistic and translational research.

AREAS COVERED

The authors review established models of in vitro cell culture and describe advances in organoid culture for studying normal and malignant intestine. They also discuss key features of classic xenograft models and describe other approaches for in vivo CRC research, including patient-derived xenograft, carcinogen-induced, orthotopic transplantation and transgenic mouse models. We also describe mouse models of metastatic CRC.

EXPERT OPINION

No single model is optimal for drug discovery in CRC. Genetically engineered models overcome many limitations of xenograft models. Three-dimensional organoids can be efficiently derived from both normal and malignant tissue for large-scale in vitro and in vivo (transplantation) studies and are thus a significant advance in CRC drug discovery.

Tumor vascular homing endgolin-targeted radioimmunotherapy in hepatocellular carcinoma

Endoglin is a proliferation-associated cell membrane antigen and overexpressed in the angiogenic vasculature of solid tumors. However, the applications of endoglin (ENG)-targeted radioimmunotheray in hepatocellular carcinoma have not been reported yet. Therefore, the aim of this study was the visualization of both the development of hepatocellular carcinoma (HCC) tumor burden and therapeutic effect with ENG-targeted (131)I-anti-ENG mAb (A8), via in vivo noninvasive fluorescence imaging (NIFLI) of SMMC7721-green fluorescent protein (GFP) cells. A8 showed a dose-dependent, time-dependent suppression on the proliferation of SMMC7721-GFP cells and human umbilical vein endothelial cells (HUVECs) in vitro. Tube formation assay showed that (131)I-A8 markedly inhibits HUVECs to form extensive and enclosed tube networks. The results showed that the radiochemical purity of (131)I-A8 was 92.8 % and (131)I-A8 maintained more stable in serum than in saline and had high affinity against SMMC7721-GFP cells. The pharmacokinetics of (131)I-A8 was in accordance with the two-compartment model, with a rapid distribution phase and a slow decline phase. NIFLI exhibited a good relation between the fluorescent signal and tumor volume in vivo. Furthermore, treatment with (131)I-A8 resulted in significant tumor-growth suppression on the basis of the reducing fluorescent signal and a remarkably decreased tumor weight in treated animals. These results were further verified by RT-PCR and immunohistochemistry staining. Our findings indicate that (131)I-A8 can be used as ENG-targeted therapy for hepatocellular carcinoma, and noninvasive fluorescence imaging provides valuable information on tumor burden and effectiveness of therapy.

New orthotopic implantation model of human esophageal squamous cell carcinoma in athymic nude mice

BACKGROUND

Subcutaneous xenograft is a common method to establish animal models of human esophageal squamous cell carcinoma (ESCC). However, the growth microenvironment of transplanted tumors is different from primary tumors. Orthotopic implantation models can provide more biologically relevant context in which to study the disease. So far, an orthotopic implantation model of ESCC has rarely been reported.

METHODS

The human ESCC cell line KYSE30 was transfected with pLVX-Luciferase plasmids. KYSE30-Luciferase cells were isolated and injected into the flanks of nude mice to develop a subcutaneous tumor. An orthotopic implantation model was established using the fragments derived from the subcutaneous tumor. Fluorescence imaging was used to observe the development of the orthotopic implanted tumor. Hematoxylin and eosin staining was performed to evaluate the invasion and metastasis of the tumor.

RESULTS

KYSE30 cells were successfully transfected with pLVX-Luciferase plasmids. A primary tumor was developed in all mice. The mice experienced body weight loss. The implanted tumor infiltrated into the esophageal muscularis propria. However, neither distant organ nor lymph node metastasis was found. The progression of the primary tumor was monitored by in vivo fluorescence imaging.

CONCLUSION

The orthotopic implantation model can be established by sewing the fragments of human ESCC to the abdominal esophagus of a nude mouse. The progression of an orthotopic implantation tumor can be monitored in real time by in vivo fluorescence imaging.

Effects of gamboge in an orthotopic mouse model of colon cancer

AIM: To study the antitumor and anti-metastatic effects of gamboge in an orthotopic mouse model developed with human colon cancer cell line HCT116.

METHODS: A colon cancer model was developed by surgical orthotopic implantation of green fluorescent protein (GFP)-expressing HCT 116 tumor in nude mice. Forty mice were equally randomized into four groups. Group 1 served as a negative control and received intragastric infusion of normal saline once daily. Group 2 received intraperitoneal injection of 5-fluorouracil at a dose of 25 mg/kg three times per week. Groups 3 and 4 received intragastric infusion of gamboge extract at a dose of 10 and 20 mg/kg, respectively, once daily. Each animal was checked for mortality and signs of morbidity every day. Primary tumor volume and metastasis for each animal were observed under a fluorescence imaging system twice a week, and body weights were measured as well. At the end of the experiment, all mice were sacrificed and open fluorescent images of tumors and metastases expressing GFP were acquired, and the tumor was removed from each mouse and weighed.

RESULTS: After initiation of different treatment regimens, the average tumor volume (mm³) was significantly smaller in the gamboge (20 mg/kg) group than the control group at each observation point (d4: 104.5 ± 35.5 vs 164.1 ± 66.1; d7: 102.6 ± 53.8 vs 286.2 ± 132.0; d11: 137.6 ± 70.5 vs 324.4 ± 115.8; d14: 207.2 ± 101.7 vs 434.2 ± 169.3; d21: 229.8 ± 99.8 vs 480.4 ± 165.5; P < 0.05 for all). At the end of the study, the average tumor weight was significantly smaller in the gamboge group (20 mg/kg) than in the control group (0.58 ± 0.26 vs 0.92 ± 0.26, P < 0.05). There were no statistical differences between the gamboge (20 mg/kg) group and 5-fluorouracil group, as well as between the gamboge (10 mg/kg) group and control group, in term of average tumor volume and weight (P > 0.05 for all). At the end of the experiment, open GFP imaging demonstrated that all groups presented metastasis of lymph nodes or the pancreas, although there were no significant differences between the four groups with regard to the metastasis rate (P > 0.05 for all). No significant morbidity or weight loss was found in all tumor-bearing mice.

CONCLUSION: Gamboge at a dose of 20 mg/kg was able to suppress HCT 116 tumor growth in an orthotopic mouse model of colon cancer safely and effectively, and may possess clinical therapeutic potential for colorectal cancer.