Differentiating
between healthy and diseased tissue is a known difficulty in removal of brain tumors.
Given the delicate nature of neurosurgery, these surgeries often take hours and
sometimes malignant tissue is left behind. It may not be much tissue, a few
hundred cells maybe, but when accessing the brain involves using a dremel to
saw through the cranium, it’s not a surgery you’d want to repeat over and over
again.
Amazingly,
researchers have developed a compound that only marks brain tumor cells, making
them fluoresce. The interesting thing is that this compound was derived from a protein found in the venom of giant Israeli scorpions. The peptide
found in the venom is called chlorotoxin and it binds to membrane proteins
expressed on the surface of cancer cells, but not healthy cells. That membrane
protein is associated with the Akt pathway – a pathway that is involved in cell
proliferation and programmed cell death and has been associated with tumor
survival.
It seems
that scientists are slowly but surely finding ways to identify and target cancer
cells. In my opinion, advancements like these are huge for our never ending
battle against cancers. This research has led to the development of a
trademarked product, Tumor Paint, developed by a team from the Fred Hutchinson
Cancer Research Center in Seattle and Seattle Children’s Hospital, which
physicians can use intraoperatively to help visualize malignant tissue.
If anyone is
interested in similar, nature-based technologies, I would highly recommend
checking out www.projectviolet.org
References
Brian Krans. Tumor
Paint May Make Brain Surgery Safer, More Effective. 2013. Healthline
News. http://www.healthline.com/health-news/tech-scorpion-venom-makes-brain-tumors-glow-under-light-091213
Grimes,
Carol A., Gonda, Matthew A., Alvarez, Vernon L. Chlorotoxin, a small peptide derived from
scorpion venom, targets cancer cells via a phosphatidylinositol phosphate. AACR
Meeting Abstracts 2005. 2005: 1300-b
Soroceanu,
Liliana, Gillespie, Yancey, Khazaeli, M. B., Sontheimer, Harald. Use of
Chlorotoxin for Targeting of Primary Brain Tumors. Cancer Res 1998 58:
4871-4879
This is awesome! I was going to ask whether or not this protein could bind to cancerous cells found elsewhere in the body but I did a little bit of research. As it turns out, the scorpion's venom is a mixture of neurotoxins that serve to immobilize prey (Ross, 2008). It makes sense that it wouldn't effect other cells. With that being said, could we potentially use other types of venom to fluoresce tumors elsewhere in the body based on the body systems they effect?
ReplyDeleteRoss, L. (2008). Leiurus quinquestriatus (ehrenberg, 1828). Retrieved from http://www.ntnu.no/ub/scorpion-files/l_quinquestriatus_info.pdf
Kiersten, I found an article that used a modified version of CTX called Chlorotoxin:Cy5.5 (CTX:Cy5.5) that was able to detect malignant glioma, medulloblastoma, prostate cancer, intestinal cancer, and sarcoma in mice models (Veiseh 2007). Although no human subjects were tested, the results show promising results for cancer in humans for the future. The American Cancer Society predicts over 238,000 new cases of prostate cancer in 2013 with some 29,000 deaths. If CTX:Cy5.5 can be used in humans, thousands of lives have have the potential to be saved.
ReplyDeleteBen, this is indeed awesome! Who would have ever thought that a neurotoxin intended for paralysis would be injected back into brain cells and used for cancer?
I watched the projectviolet video and even though I am encouraged that non-profits are dedicated to the research and development of new drugs for rare diseases, I am still shocked by the exorbitant amount of money that is involved in the process. Like Dr. Olson stated, it may cost well over $50 million to develop a new treatment (not to mention the time it takes to receive approval from the FDA). Let's use this $50 million as an example: even if a rare disease is found in 5,000 individuals, each must pay $10,000 each just for the drug company to break even. This is still a large amount of money for many. I know we live in a capitalistic society, but I can't help but think of the ethics of some situations. What do you think about the fact that those with rare diseases are not even given a chance of a cure due to the high cost? Is there really a price to be placed on a human life?
References:
American Cancer Society. Cancer Facts & Figures 2013. Atlanta: American Cancer Society; 2013
Veiseh M, Gabikian P, Bahrami SB, Veiseh O, Zhang M, Hackman RC, Ravanpay AC, Stroud MR, Kusuma Y, Hansen SJ, Kwok D, Muno NM, Sze RW, Grady WM, Greenberg NM, Ellenbogen RG, Olson JM. Cancer Research 67:6882-6888, 2007.
How is an "optide" method of cancer treatment different from miRNA used in RNA interference?
ReplyDelete