The survival of tumor cells depends both on their own characteristics and on the parameters of the microenvironment, which consists of vessels, cells of the immune system, connective tissue components and the extracellular matrix, nerve and endocrine cells may also be present.
In addition, there is a large number of signaling molecules which regulate both the immune response and the cellular processes of a tumor, like division and metastasis. Cancer forms a microenvironment itself, some types of tumors have the ability to produce a variety of VEGF protein which triggers the migration of vascular endothelial cells to the tumor and their division. Such tumors grow and metastasize faster.
This photomicrograph shows the cells of the breast cancer and their microenvironment. > White cells with a green nucleus – proliferating tumor cells, the marker – protein Ki67; > White cells without visible green color – non-proliferating, quiescent cells; > Red color – vascular endothelial cells, marker – CD31; > Blue color – the nucleus of cells, marker – DAPI.