Utilizing Heat Shock Protein 90 in Breast Cancer Imaging: A Cheaper Alternative?

By Riya Gandhi ‘22

Figure 1. Chaperone proteins such as Hsp90 aid in protein folding.

In the current day and age, therapeutic procedures for breast cancer–such as chemotherapy, radiation therapy, and surgery–are at the forefront of the initiative to manage cancer effectively. Across the globe, there are nations where the resources for such treatments are readily available. However, what about the low to middle income nations? Unfortunately, many of these countries, which hold higher rates of breast cancer, do not have the resources to provide their patients with procedures that would save their lives. Due to this, scientists are looking into molecular diagnostics as a cheaper alternative to routine pathology.

Under principle investigator Dr. Brian Crouch, researchers at Duke University examined imaging Heat Shock Protein 90 (Hsp90) as a molecular diagnostic target for breast cancer. Hsp90 is a chaperone protein which aids in the folding or unfolding of other proteins. However, not only is this a chaperone protein, but it also stabilizes proteins that are necessary for the proliferation of tumors. As it is expressed widely in invasive breast cancers, it is the perfect target. First, the researchers created HS-27, which is a fluorescent inhibitor of Hsp90, as it allowed the researchers to assay expression of Hsp90 on the intact breast cancer tissue specimens. Next, the researchers developed three imaging parameters for the preclinical studies: time between tissue excision and staining, agent incubation time, and agent dose. The agent in this case is HS-27. The optimal setting was a post-excision window of 1-10 minutes, incubation time of 1 minute, and a dose of 100µM. Once optimized parameters were in place, the researchers transferred them to the actual clinical breast cancer samples. These samples were from patients that were estrogen receptor positive, had overexpression of Her2–an oncogene that serves as a receptor for normal cell growth and differentiation– and were triple negative in receptor subtypes. In doing so, they discovered that the fluorescence was most prevalent in tumor tissue, but to their surprise, these same samples were also highest in Her2+ and triple negative subtypes. As such, the fluorescence permitted accurate distinction of the tumor from benign tissue.

This experiment is quite crucial to the field of oncology–as well as medicine as a whole as it points to a procedure that is cost-effective and less intensive than previous cancer therapies. Although there is more research that must be done to qualify this as the future of molecular diagnostics, it does hold much promise.

  1. B. Crouch, et. al., Exploiting heat shock protein expression to develop a non-invasive diagnostic tool for breast cancer. Nature, (2019). doi: 10.1038/s41598-019-40252-y.  
  2. Image retrieved from: https://www.pexels.com/photo/green-flower-bouquet-on-white-background-961402/

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