Elucidating the involvement of Src Kinase substrates, Tks4 and Tks5, in mechanisms of tumor dormancy, progression and metastasis
We are working on several breast cancer cell lines in vitro, using 2D and 3D cell culture techniques to define the role of Tks5 in the formation of invadopodia and in the ECM. Our former lab manager, Ronn Leon developed several novel human Tks5 monoclonal antibodies currently used in our research. These antibodies are opening a new world of understanding regarding the cellular localization and roles of Tks5 in cancer cells.
Kinases important for functional invadopodia formation in cancer progression.
Shinji is researching invadopodia-related kinases that have been identified using high content invadopodia screening assay. Currently these candidate kinases are being validated in several cancer types and will be assessed as cancer therapeutic target.
The adaptor protein Tks5 is a critical molecule for invadopodia formation.
Shinji is also studying the role of invadopodia in cancer progression, especially melanoma and breast cancer, using a mouse model to reveal the role of invadopodia in cancer progression in vivo.
An inducible melanoma mouse model to determine whether primary melanoma tumor growths require invadopodia and Tks5
Invadopodia are involved in most steps of tumor cell metastasis, including basement membrane degradation, local ECM remodeling and invasion, intravasation into blood vessels, extravasation out of blood vessels, and growth at metastatic sites. In our lab, we have directly shown that melanoma growth and metastasis require Tks5 and invadopodia; however, these experiments utilize cell lines derived from tumors that have already metastasized. It remains unknown whether primary tumor growth requires invadopodia and Tks5. To address this question, Shinji is using the well-established, inducible, Braf/Pten metastatic melanoma mouse model in conjunction with the loss of Tks5. Our Tks5-melanoma mouse model will enhance our understanding of whether or not invadopodia contribute to primary melanoma tumor formation;these insights will be useful in understanding how to target primary tumor growth to prevent a metastatic phenotype.
Understanding vemurafenib sensitivity in melanoma invadopodia formation, invasion capability and growth in 3D collagen
Over 50% of cutaneous melanomas harbor a mutation in BRAF. Vemurafenib, a well-tolerated, competitive small-molecule inhibitor of BRAFV600E-mutant melanomas, was FDA-approved in 2011 to treat late-stage metastatic melanoma. However, most patients acquire resistance to the drug within six months of beginning treatment, provoking research on resistance mechanisms and possible combination therapies to alleviate such resistance. Intriguingly, numerous studies have reported that vemurafenib-resistant melanoma cells are more invasive than their drug-naïve counterparts in vitro, providing evidence that invadopodia may play significant roles in how vemurafenib-resistant melanomas achieve resistance and become more aggressive, metastatic tumors. We are currently working with four different sets of melanoma cell lines, each with a vemurafenib-sensitive and a vemurafenib-resistant counterpart, in order to understand how vemurafenib resistance impacts Tks5 expression, invadopodia formation, invasion and 3D growth capabilities. Understanding how vemurafenib-resistant melanomas grow, invade and metastasize will be important in developing targeted combination therapies to improve the efficacy and overall outcome of vemurafenib treatment in metastatic melanoma patients.
Simple illustration of the melanoma mouse model experimental strategy: 4-hydroxytamoxifen will be used to induce the constitutive activation of BrafV600E and Pten loss, in conjunction with or without Tks5. Due to the CreER driven by the tyrosinase promoter, these genetic changes only happen in melanocytes.