Kelly Tran's HER2 aptamer project (2014)
Therapeutic Nucleic Acid Aptamer Selection against Human Epidermal Growth Factor Receptor 2 to Inhibit Growth of Cancerous Breast Cells
Kelly Tran- Spring 2014
1 in 8 women are likely to have breast cancer and 1 in 36 dies from it.1 Although there are multiple therapeutic treatment for breast cancers, a cheaper alternate therapeutic treatments should be discovered to counter these cancerous cells. Human epidermal growth factor receptor 2 also known as HER2 is an important receptor when overexpressed can lead to breast cancer.2 HER2 is a biomarker that is the target of 30% of breast cancer patients.2 Herceptin is an antibody that targets HER2 but is expensive to attain, whereas aptamer that targets HER2 would be a cheaper alternative.
Aptamers are molecules that bind to a specific target. Nucleic acid aptamers are single stranded DNA (ssDNA) or RNA that binds to a specific target. The aptamer whose target is HER2 will serve as a therapeutic aptamer. It will inhibits the function of HER2 thus inhibits the breast cancer cells from replicating. Although an antibody for HER2 have been found, an aptamer would be more beneficial. Several reasons as to why an aptamer would be more beneficial are that the aptamer would be easily created in lab and the cost of the aptamer would be significantly less than that of creating the antibody. Thus allowing the cost of treatment to drop and be more available to those who could not afford the treatment at first.
In vitro aptamer could be synthesized through a filter based selection or a bead based selection. A bead-based aptamer selection will be performed because HER2 is his-tag and his-tag protein would easily bind to nickel beads. The target will be subjected to several rounds of bead wash, to wash away unbounded nucleic acids which would then undergo ethanol precipitation. After reverse transcription, they would undergo PCR. After PCR, the ssDNA would go through transcription. The whole procedure is then repeated for several more round. After several successful rounds, an aptamer would be created with the leftover sequence. This aptamer could then be used to target HER2 as a cheaper alternative to the more expensive antibody Herceptin.
Figure 1 shows two scenario. The first scenario is when the HER2 is active and have nothing inhibiting its function. Since there is nothing inhibiting its signaling pathways, HER2 is able to send signals causing the breast cancer cells to replicate. The second scenario is when the HER2 is inhibited. In this case, a HER2 aptamer is inhibiting HER2 from performing its function, thus renders the receptor to be useless and not able to promote growth of the breast cancer cells.
Budget:
HER2 (currently available in lab)
Sino Biological Inc
Phone Number: 86-400-890-9989
Website: http://www.sinobiological.com/HER2-ErbB2-Protein-g-1492.html
Catalog Number: 10004-H08H-50
Molecular Weight: 71 kDa
Cost: $298 for 100 ug
Cost per round: $42.57 (200pmol)
References
1. "How Many Women Get Breast Cancer?" How Many Women Get Breast Cancer? N.p., n.d. Web. 27 Aug. 2014.
2. Mitri Z, Constantine T, O'Regan R (2012). "The HER2 Receptor in Breast Cancer: Pathophysiology, Clinical Use, and New Advances in Therapy". Chemother Res Pract 2012: 743193. doi:10.1155/2012/743193. PMC 3539433. PMID 23320171