The role of the tumor microenvironment in metastasis studied by intravital imaging

Abstract

Most cancer related deaths are caused by the formation of metastasis, a multi-stage process whereby tumor cells spread from the primary tumor to a secondary site. This process is not only influenced by the tumor cells itself, but also by cells of the host often referred to as the microenvironmental cells. This microenvironment consists of several different cell types together with proteins and extracellular matrix. Although many effort is made in unraveling the process of metastasis and the role of the microenvironment, there are still many questions unanswered. In this review I will focus on a new technique that is used to study tumors and their progression. This technique, termed intravital imaging, is very suitable to study the process of metastasis in vivo in real time. I will especially discuss the use of intravital imaging to study the behavior of microenvironmental cells in mammary tumors and their possible role in metastasis. The microenvironmental cells will be limited to three types, macrophages, T-cells and fibroblasts. Several studies already revealed some of their influences and their migration behavior. However, there are still a lot of interesting areas of research that are not yet studied. Especially the possibility to study the effects of cancer treatments on microenvironmental cells will be interesting for the future and might be translated into the clinic. Therefore, intravital imaging is a technique that provides a lot of opportunities for further cancer research in the future.