Imageable clinically relevant mouse models of metastasis

Development of a metastatic murine colon cancer model

BACKGROUND

It has now become clear that the complex interplay of cancer and the immune responses against it plays a critical role in the tumor microenvironment during cancer progression. As new targets for cancer treatment are being discovered and investigated, murine models used for preclinical studies need to include intact immune responses to provide a closer correlation with human cancer. We have recently developed a modified syngeneic orthotopic murine colon cancer model that mimics human colon cancer progression with consistent results.

MATERIALS AND METHODS

Tumors were created using the murine colon adenocarcinoma cell line, CT26, modified to overexpress the firefly luciferase gene (CT26-luc1), which allowed real-time in vivo monitoring of tumor burden when the substrate, D-luciferin, was injected intraperitoneally using the In Vivo Imaging System. Mice are Balb/c (Harlan), syngeneic with the CT26-luc1 cells. Cells are injected submucosally, suspended in Matrigel, into the cecum wall under direct visualization.

RESULTS

The model has demonstrated consistent implantation in the cecum. In vivo bioluminescence allowed real-time monitoring of total tumor burden. Perioperative preparation had a significant impact on reproducibility of the model. Finally, total tumor burden quantified with bioluminescence enabled estimation of lymph node metastasis ex vivo.

CONCLUSIONS

This method maintains an intact immune response and closely approximates the clinical tumor microenvironment. It is expected to provide an invaluable murine metastatic colon cancer model particularly in preclinical studies for drug development targeting those mechanisms.

Application of fluorescent proteins in tumor research

Fluorescent proteins have been applied in multiple tumor research fields, including tumor cell growth, invasion, metastasis, angiogenesis, the interaction between tumor cells and host cells, and antitumor drugs. Fluorescent imaging has enabled what was formerly invisible to be seen clearly in vivo with fluorescent proteins. This article will make a brief review of the application of fluorescent proteins in tumor research.

Establishing a human renal cell carcinoma tumorgraft platform for preclinical drug testing

Traditionally, xenograft models have been used to study tumors in vivo. However, their utility is reduced by the use of tumor cell lines for implantation. Tumorgrafts (TGs; also known as patient-derived xenografts (PDXs)), which involve patient-derived tumor samples, are increasingly recognized as more representative models than traditional xenografts. Furthermore, we showed previously that renal cell carcinoma (RCC) TGs retain the histology, gene expression, DNA copy number alterations, mutations and treatment responsiveness of patient tumors. In skilled hands, implantations require ≤5 min per mouse, and TGs typically grow to 1 cm in 1-4 months. Here we outline the process of implantation of patient-derived RCC samples into the kidneys of immunodeficient mice, as well as the s.c. implantation for preclinical drug testing, including guidelines for the design and execution of drug trials. TGs have extensive applications besides therapeutic studies and may identify biomarkers and mechanisms of resistance. In addition, they may provide insights into tumor biology.