Elucidating novel molecular and cellular mechanisms in Tenascin-C dependent breast cancer aggressiveness

The microenvironment, which comprises the extracellular matrix (ECM), plays instrumental roles during tumor formation and progression. Tenascin-C (TNC) is a major ECM component highly expressed in breast cancer, correlating with poor prognosis, tamoxifen resistance and lung metastasis formation. TNC exerts pleiotropic effects by promoting tumor cell survival, proliferation and invasion as well as angiogenesis , inflammation and metastasis. The main goal of my thesis was to try to comprehensively understand the several contributions of TNC during breast cancer establishment and progression to metastatic disease. My analyses revealed that the absence of TNC does not affect breast tumorigenesis in the MMTV-PyMT breast cancer mouse model, confirming a previous study. More interestingly, using the MMTV-NeuNT model, we show that TNC promotes primary tumor initiation and lung metastatic colonization. In the lung, TNC increases of cancer cell survival in intravascular metastases and promotes their progression. Additionally, we established breast cancer cell lines from MMTV-PyMT and MMTV-NeuNT mouse models that grow in vitro and are tumorigenic when re-Implanted in syngeneic, fully immuno-Competent mice. In this work we had shown that TNC participates in tumor initiation and in lung metastasis colonization in an ErbB2-Driven transgenic breast cancer mouse model. The established cell lines are alternative tools useful for in vivo and in vitro studies in breast cancer research.