Replacing in vivo models with the Quasi vivo system to investigate metastatic site priming by tumour cells.

Metastasis is the movement of cancer cells away from the site of a tumour (the primary site) to other areas of the body where a secondary cancer forms (the metastatic site). In breast cancer, metastasis is responsible for nearly all deaths from the disease, more than 11,000 people each year in the UK, and so there is an urgent need to learn more about the complex series of events which leads to disease spread and progression to terminal disease.

In order for a breast cancer to metastasise the cancer cells need to adapt so that they can leave the primary site, survive within the blood stream whilst they travel to the new site and, most importantly, so that they can live in a new environment, most commonly the bone, lung, liver and brain. Equally important to the cancer cell adaptations are the changes that need to occur at the metastatic site, and this has been described as the "seed and soil" hypothesis - you can scatter many seeds on the ground but if the soil is not suitable the plant will not grow, comparably many tumour cells may move around the body but if they do not find a suitable site, they will not form a secondary tumour. We believe that the primary tumour plays an important role in preparing the metastatic site for cancer cell arrival - it makes the soil suitable for the seed.
To test this hypothesis studies have previously been carried out in animals aiming to identify the signals which are driving these changes. Due to the complexity of these models and the lack of control in a living system progress to date has been limited.

Here we propose a novel laboratory-based, cell line system which we can use to model the interactions between the breast cancer cells and the likely sites of metastasis. This system is based on one which Professor Arti Ahluwalia has developed and which she uses in Pisa to model tissue interactions and metabolism in the abdomen for example.
We will adapt this model for use in breast cancer metastasis modelling for use in Manchester and ask what signals the breast cancer cells are sending to the distant tissues to prime them for cancer cell arrival. If we can find ways to block these signals, we will reduce secondary tumour formation and the associated patient mortality.

Most breast cancer deaths result from metastasis and there is, therefore, an urgent need to understand the complex sequence of events that leads to recurrence. We hypothesise that the primary tumour influences the potential metastatic sites by signalling to them and directing them to change their environments making them suitable for the cancer cell's arrival.

We will develop an in vitro method to model niche priming in which we can investigate the interactions between primary breast cancer cells and the typical sites of metastasis including bone, brain, liver and lung. We will use the Quasi vivo system in which cells from each site can be cultured in separate but connected chambers between which medium will flow constantly allowing signals released at one site to reach the others. We will identify the best culture conditions for our different cell types within the system by assessing different media composition, flow rates and cell density. We will then co-culture our breast cancer cells and distant site cells (Fibroblasts, osteoblasts, lung epithelium, hepatocytes and endothelial cells) and assess whether we can see changes in growth, survival and behaviour of each cell population.

This work will contribute to the NC3Rs aims to reduce and replace animal models as it will provide an alternative to rodent models of metastasis which will be applicable in cancer research.