Description
Colon Cancer
Colorectal cancer is the third common cancer and accounts for 9.7% of all cancers. More than half of the cases occur in well-developed regions of the world due to higher elderly population, unhealthy eating habits as well as continuous increase in risk factors.
In recent years, the incidence and mortality of colon cancer in China has also been on sharp increase .
In some well-developed cities such as Shanghai, the incidence of colorectal cancer has rose to the second place among all the other cancers, and even in rural areas the occurence has also risen up to the fifth place .
Visit our Background page for more shocking details about colorectal cancer.
Why Do We Aim On Early Screening Of Colorectal Cancer?
Early screening is of great significance in inhibiting the progress of colorectal cancer. The earlier the disease is diagnosed the more rapid proper treatment can be given. For the past few years, early screening of colorectal cancer has been promoted and carried out accross the country. However, due to the large imbalance in the level of medical care across mainland China, with the existing screening methods, colonoscopy, being either expensive or painful, early screening for colon cancer remains limitied.
On the other hand, synthetic biology has shown great potential as well as brand new perspectives in diagnosis and therapeutic fields for numerous severe diseases. As a result we wonder if it is possible to develop a cheaper, more convenient screening method using synthetic biology. Against all odds, we proudly present our design, ECHO.
What is ECHO?
ECHO, short for "E.coli for colon health observation", is how we name our device. The name highlights the most important part of our project, visualizing cancerous section with ultrasound instead of currently-used colonoscopy.
How Does ECHO Work?
The design of ECHO involves four parts: localization, imaging, and medicine synthesis and release.
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Localization
It has been proved that high level of T antigen, a kind of glycoprotein, is expressed on the surface of cancerous cells. Utilizing this characteristic, we equipped ECHO with a oligo peptide that specifically binds with T antigen. As a result, after being introduced in the digesting system, our device anchors on cancerous area and is capable of expressing further engineered functions.
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Imaging
Other than visible light used in traditional screening method, our project uses acoustic reporter genes, ARGs, for visualization under ultrasound. When ARGs is expressed, our device produces 200 nm in diameter gas vesicles that are visible in supersonic range. In other words, when ECHO is introduced into the digesting system, it produces signals that can be detected non-invasively using ultrasound.
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Medicine Synthesis and Release
Besides diagnosis use, we've also engineered ECHO to help inhibit the progress of cancer. Nitric oxide is a distinguishing factor near cancerous area where its level is a lot higher than it is in normal tissue. When our device is exposed under such high level of nitric oxide,it produces azurin, a chemical that kills cancerous cells. However not until the bacteria collapse does the substance get released to the system. And this is why we've designed a suicide pathway triggared by arabinose to enable normal functioning of azurin. When our patient consumes arabinose, ECHO starts to collapse, guaranteeing both cancer progress inhibition and biosafety.
Visit Design page for more details.
How does ECHO look like?
Since the ultimate goal of this project is to develop an actual device that is applicable in real life, the product design after the bacteria being engineered is undoubtedly important.
To construct a real product we first have to lyophilize our bacteria into powder. However powder form of bacteria could not arrive at our target area and is difficult to consume, so a loader is being designed and utilized. There are two types of loader we have chosen, the capsules and the Hydrogel beads. Both of the loaders have the ability to maintain until arriving at target area, releasing ECHO into colorectal section. With these coating our device finally has a more appealing look has moved one big step closer to reality.
Reference
[1] Valori, R., Rey, J.-F., Atkin, W. S., Bretthauer, M., Senore, C., Hoff, G., . . . Minoli, G. (2012). European guidelines for quality assurance in colorectal cancer screening and diagnosis. First Edition--Quality assurance in endoscopy in colorectal cancer screening and diagnosis. Endoscopy, 44 Suppl 3, SE88-105.
[2]Chen, W., Zheng, R., Baade, P. D., Zhang, S., Zeng, H., Bray, F., ... & He, J. (2016). Cancer statistics in China, 2015. CA: a cancer journal for clinicians, 66(2), 115-132.
[3]高颖,石磊. (2018). 某院就诊中老年人群结肠癌结肠镜筛查结果研究 [J]. 中国内镜杂志, 1-7.
