Conference Proceeding

Understanding the dynamics of tumor microenvironment using humanized zebrafish tumor xenograft systems

Dr. Vinoth Sittaramane,
Georgia Southern University

Present day cancer incidence and mortality rates indicate the need for effective cancer diagnostic tools and targeted cancer therapeutic strategies.

Dr. Vinoth Sittaramane carried out is Doctorate of Veterinary Medicine in Pondicherry University and MVSc (Biotechnology) in Indian Veterinary Research Institute in Bareilly, India. He further did his PhD and Post-doctoral residency work in University of Missouri, Columbia, USA. Presently, he is working as Assistant Professor at Georgia Southern University, USA.

Present day cancer incidence and mortality rates indicate the need for effective cancer diagnostic tools and targeted cancer therapeutic strategies. Recent studies have focused on the biological pathways of cells and tumor micro environments to identify putative biomarkers and potential drug targets as diagnostic and therapeutic tools. Human integrins, transmembrane adhesion receptors, have become the focal points in these studies, specifically Integrin Alpha 6 (ITGA6) which has been implicated in major tumor progression roles. Several human tumors like pancreatic, prostate, breast and ovarian cancers exhibit increased levels of ITGA6 expression (Marthick JR et al., 2012; Lathia JD et al., 2010; Hirozumi S et al., 2006; Johnatty S et al., 2010). ITGA6 has been implicated in tumor angiogenesis, metastasis and cancer stem cell maintenance (Primo L et al., 2010; Wang J et al., 2013; Carrion B et al., 2013). These characteristics make ITGA6 an excellent candidate for potential drug or diagnostic target, however the mechanism by which ITGA6 imparts tumor progression is unclear. Cell culture studies have indicated ITGA6 could be cleaved extracellularly to increase metastasis (King TE et al., 2008; Cress AE et al., 2014). But, zebrafish with organismal structures and vascular network presents a complete in vivo model to track metastasis and angiogenesis. In the present study we aim to identify the specific role of ITGA6 in tumor development by using a humanized zebrafish model, where Di-I labeled human prostate cancer cells (PC3) are transplanted into Tg zebrafish embryos that is over expressed with various forms of human ITGA6. To test the domain specific role of ITGA6, Human full length or truncated extracellular or mutated non-cleavable ITGA6 RNA is injected to the zebrafish PCs tumor xenograft. Our studies indicate that truncated ITGA6 over expression significantly increases tumor metastasis compared to full-length ITGA6 over expression. Similarly, mutated ITGA6 significantly decreased the tumor metastasis. The results suggest that cleaved ITGA6 increases tumor metastasis potentially aiding in extracellular matrix remodeling. The cellular role of ITGA6 will be evaluated by transplanting ITGA6 siRNA transfected PC3 cells for zebrafish tumor xenografts. We anticipate these experiments will help establish the cell and non-cell autonomous roles of ITGA6 during tumor development. Further, high resolution imaging of migration of single cancer cells has allowed us identify the increased protrusive behaviors and laminin digestive ability of metastatic cancer cells. These studies are helping us understand the dynamic matrix remodeling events that occur in tumor micro environment and would potentially aid in developing novel targets for cancer diagnostics and therapeutics.

Published: 11 May 2017