Zebrafish model: worth considering in defining tumor angiogenesis.

The process of angiogenesis is essential for tumor progression and metastasis; however, antiangiogenesis therapy-induced hypoxia and inflammation are perhaps the driving force for tumor escape and metastasis formation, thereby compromising its efficacy. This warrants the complete understanding of the molecular and cellular basis of antiangiogenesis therapy and necessitates the identification of potential signaling events in the host microenvironment, which are involved in tumor angiogenesis and metastasis, to improve the treatment of cancer. In this context, the zebrafish/tumor xenograft model represents an emerging vertebrate system to study the correlation between tumor angiogenesis, inflammation, and metastasis and to better understand the modification of tumor microenvironment by antiangiogenesis therapy. This review article describes the necessity to study the microenvironment of host-tumor interface by introducing basic concepts of angiogenesis, emerging paradigms, and challenges of antiangiogenesis therapy and provides an update on the importance of the zebrafish/tumor xenograft model to address these issues.