Forsøksdyr: Breeding of transgenic mouse strain (Axl GFP_cre-ERT2) to study the role of axl in mammary gland development and cancer

Godkjenningsdato 05.01.2018

1. Purpose of the study.
In this project, we want to breed a transgenic mouse strain expressing cre recombinase after the Axl sequence (provided by oZgene Company) allowing physiological Axl to express in addition to GFP. We will cross these with wildtype C57Bl/6 to obtain and expand the colony, and the Rosa26-LSL-Tomato mouse strain in order to follow lineage tracing. In order to activate the Tomato, mice will be treated with Tamoxifen.
2. Expected harm/severity for the animals.
We expect no injuries for the animals during this experiment. A small part of the ear will be cut to genotype the animals; this is a common practice.
3. Expected benefit for science or society
We may discover novel mechanisms of Axl as a stem cell marker during linage tracing experiments which in turn allow for possible treatment towards aggressive axl expressive cancer.
4. How many and what kind of animals will be used (totally in this experiment)
Based on previous experience on mouse colony creation and expansion, the maximum amount of mice needed will be 1600. We will first start with three breeding pairs from the new made mice. We will as well cross those mice with wild type C57Bl/6 mice. For particular projects, separate applications will be submitted.
5. How are compliance with the requirements for replacement, reduction and refinement safe guarded.
As this application regards breeding of mice, in vitro experiments is not possible. We would like to prove that Axl act as a mammary stem cell marker in epithelial cells. In order to follow Axl expression and see the fate of those cells, in vivo lineage tracing experiments is the only method available to answer our scientific question. The number of animals have been reduced by in vitro studies prior to in vivo experiments. Furthermore, animals will be used for both in vivo and ex vivo studies. As breeder pair, the same animals will be used over time. For breeding we will use heterozygotes to benefit from increased production of offspring during the experiments. Breeding will be performed according to planned experiments in order to further reduce the number of animals. We will use our breeding experience in the field to refine the housing of animals and fully optimize the life of every animal used.