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Team:Purdue/Project
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Abstract
Glioblastoma multiforme (GBM) is one of the most common forms of primary brain cancer, which usually results in fatality. To date, it has been difficult to overcome primary brain cancer resulting from GBM, primarily because the cancer-initiating cells are suspected to be highly resistant to current cancer therapies. The present study is focused on CD133+ cells found in primary GBM samples. CD133+ cells have shown resistance to hypoxia, irradiation, and some forms of chemotherapy. CD133+ hunting machines will be created by genetically engineering microglial cells (BV-2) with two constructs using mammalian expression vectors. The project will also take advantage of inherent qualities of the microglia such as constant environmental sensing and quick motility. The engineered BV-2s will be equipped to locate the specific GBMs and label the targeted cells with a tat-GFP fusion protein. To create an in-vivo-like environment, the cells will be grown in 3D collagen media. This would create a maze and challenge the microglia to seek out the cancer cells. Cell sorting techniques will be used to measure the accuracy in hitting positive targets, the CD133+ cells. It is the goal of this study to show an alternative approach to cancer treatment, and to emphasize the power of biologically available options to fight the disease.
Project Details
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The Concept
The basic idea is to use the naturally mobility of a microglial cell to find a specific cell found in 1% of some glioblastoma multiforme.
Microglial cells are the macrophage of the central nervous system. They are needed due to the blood brain barrier that is necessary for our system to work. In a resting state, the microglia have extensions that are constantly surveying the environment. The microglia interpret signals from the environment and act accordingly. The microglia have the ability to "clean up" dead cells and debris via endocytosis.
Glioblastoma multiforme is made up of many different cell types that make this primary tumor difficult to destroy. Also, in the center of some of these tumor masses, scientists have found a small subset of cells that display stem cell-like qualities. They have been shown to be resistant to hypoxia, irradiation, and some chemo-therapies which indicate to some as a possible reason why recurrence is so high in patients diagnosed with glioblastoma multiforme.
We plan to achieve this goal by creating a chimeric receptor that is specific for the 1% subset of cells we are attacking. This small population is CD133 positive. This protein is a marker found on some stem cells, but as of right now no one has fully characterized CD133. We will use part of the CD133 antibody (Fab region) and most of the Fc gamma Receptor to create this very specific chimeric receptor. The Fc Receptor is native to the microglia, and thus have the pathway needed to reach the nucleus. As of right now, we are planning on using the C-Jun promoter to create our tat-GFP fusion protein.
Tat is a cell penetrating peptide that was first discovered by two independent labs studying HIV-1. While the mechanism is not quite known, tat has the ability to cross cell membranes with ease. Using this inherent quality we want to attach it to GFP to create a fusion protein that can label the CD133 cells. The idea being, if it can be labeled it can be killed.
In the future, we would hook up an apoptitic factor to the tat to attempt to kill the cells.
Overall, we have created a seek and destroy system that is modular and can be adapted to other problems in the human body.
