A Novel Mouse Model of Gepatocellular Carcinoma Induced by c-Myc Overexpression
PRESENTER:
Dan Feng | Business Development Manager at Shanghai Model Organisms Center
ABSTRACT:
Authors: Jinjin Wang, Dan Feng, Haiyan Zhu, Lei Ci, Zhipeng Wan, Ruilin Sun
Hepatocellular carcinoma is a fatal liver cancer, and there are limited treatment options for this cancer. c-Myc is a key oncogene in liver cancer, but the specific mechanism of carcinogenesis in liver is unknown. Animal models are widely used to explore the molecular pathogenesis of HCC and test new drug candidates. In this poster, we reported a c-Myc conditional over-expression mouse model (LSL-Myc), which inserts the CAG-Loxp-stop-Loxp-c-Myc-polyA expression cassette into the H11 site. The expression of the Myc gene in this mouse model is regulated by Cre recombinase, which is not normally expressed, but only expressed in Cre-expressing tissue cells. LSL-Myc / Alb-cre double-positive mice were produced by crossing LSL-Myc hybrid mice with Alb-cre mice. In this mouse model, c-Myc was specifically expressed in liver cells. LSL-Myc / Alb-cre double-positive mice show a typical HCC phenotype and show accelerated tumor initiation and rapid HCC progression. Mice can detect significant liver tumorigenesis at 2 months of age, and 100% mice can occur hepatocellular carcinoma. We developed another mouse strain in which a luciferase (Luc) cDNA, preceded by aLoxP-stop-LoxP (LSL) cassette, was introduced into the ubiquitously expressed ROSA26 locus. LSL-Luc mice expressed luciferase in a liver-restricted pattern, as determined by noninvasive, bioluminescent imaging, when crossed to the LSL-Myc / Alb-cre double-positive mice. The liver cancer tissues from LSL-Myc / LSL-Luc / Alb-cre triple-positive mice can be transplanted to C57BL/6 mice to establish a visible mouse-derived allograft (MDA) model. MDAs could mimic the pathological histology and the high proliferation characteristics of HCC. Further, Lenvatinib suppressed the tumor growth of MDAs significantly. In summary, this c-Myc-induced model has the advantages of rapid oncogenesis and high incidence of liver cancer. And MDAs are effective for investigating the progression and treatment of hepatocellular carcinoma.
A Reporter Mouse Model Enabling Image-Based Evaluation of CD8+ T Cell Dynamics in Immunocompetent Allografts
PRESENTER:
Dan Feng | Business Development Manager at Shanghai Model Organisms Center
ABSTRACT:
Authors: Dan Feng, Haiyan Zhu, Lei Ci, Zhipeng Wan, Bosong Zhao, Ruilin Sun
Immune cell recruitment to tumors is indispensable for the success of immunotherapy. In vivo bioluminescence imaging technology to visualize the location and functionality of immune cells is of great value for immuno-oncology research. Here, we describe the generation of a genetically engineered mouse model “Tluc” in which all CD8+ T cells constitutively express a novel luciferase reporter Akaluc. On the C57BL/6 background, the IRES-Akaluc-EGFP expression cassette was placed downstream of the translation stop codon of the endogenous Cd8a gene, allowing the bioluminescence imaging of CD8+ T cell location and function under physiological and pathological conditions. As expected, the engineered mice showed constitutive luciferase expression in lymphoid organs such as thymus, lymph nodes and spleen under normal conditions. We next modeled the T cell dynamics in the context of tumor transplantation. In the case of subcutaneously implanted mouse cancer cells such as MC38 colon cancer cells and antigenic SIY-expressing B16 melanoma cells (but not the regular B16 cells), the reporter mice showed T cell recruitment and infiltration into the tumor mass. Besides, a higher level of T cell response was visualized when we treated tumor-bearing, Tluc mice with mouse anti-PD-1 mAb. This apparent immune response was consistent with the simulation. Our study underscores the utilities of such reporter mice for uncovering the role of immune cells in tumor responses by revealing dynamics, interactions and distribution of various immune cells in tumor settings.