Dr. Joyce Schroeder’s new peptide-based therapy may prove extremely useful in the world’s ongoing battle against cancer.
Peptides are small chains of amino acids that form structures called proteins, which play numerous important roles in human cells.
We all know someone who has experienced—or even succumbed to—the horror that we call cancer. It’s a disease not caused by the dysfunction of one gene, but by the dysfunction of many.
The National Cancer Institute estimated that over 1.5 million people would develop cancer in 2015 alone, and of those 1.5 million, over one-third would die. Cancer is a disease that doctors and researchers still have an extremely difficult time treating, even after the advances made in chemotherapy, radiotherapy and immunotherapy.
Schroeder is a leading cancer researcher at the Arizona Cancer Center and professor in molecular and cellular biology at the UA. She has developed a new treatment that may help those with metastatic breast cancer. The most promising part about Schroeder’s drug is that pre-clinical trials in mice demonstrated no detectable toxicity. Her lab discovered a cellular process that happens in cancer cells—specifically the epithelial cells of the breast—but not in normal cells. This is what she targeted.
Her work so far has shown that a small peptide called PMIP can simultaneously impact the functions of three different cancer-driving proteins: SRC, EGFR and beta-catenin. SRC was the first oncogene to be discovered, and is a major driver of metastasis. EGFRs (epithelial growth factor receptors) can contribute to excessive cancer cell proliferation. Beta-catenin is a protein that can also induce proliferation in cancer cells whose regulatory mechanisms are absent or nonfunctional.
The Schroeder lab has shown that PMIP can inhibit the function of all three of these proteins, which severely hinders any attempt that a cancer cell makes at metastasis. Results from mouse studies showed that, when injected with PMIP, tumors shrunk dramatically.
Schroeder’s interest in science started young.
“I had a mother who loved to point out natural phenomena,” she said. “There was never a time in my life where nature wasn’t cool and I didn’t want to learn more about it.”
Her fascination with science continued into college. She obtained her Bachelor of Science in microbiology from the UA, and proceeded to pursue studies in the subject in graduate school at the University of North Carolina, Chapel Hill.
Schroeder said that she tried multiple labs in graduate school, and eventually ended up in a lab that employed virology to identify new oncogenes, or genes that when over-expressed, contribute to tumorigenesis.
She hasn’t stopped working on cancer since. So why does Schroeder believe that her new therapy may prove so much more effective than those we see advertised on TV?
“Most [of these drugs] are being marketed not by scientists, but by people who are good at marketing that overemphasize the good and do the opposite for the bad,” she said. “The vulnerable are being misinformed.”
TV ads often don’t convey the seriousness of side effects brought on by some cancer drugs, which can sometimes be as uncomfortable for patients as the disease itself. Data from studies in mice has revealed that PMIP activity is observed for up to four hours in breast cancer cells, but not in normal cells. This means (in theory) that only cancerous cells die; healthy ones do not. Many therapies are non-specific, meaning that they affect all of a certain type of cell—not just the cancerous ones. Often, this lack of specificity causes side-effects such as immune system dysfunction, diarrhea and vomiting.
Schroeder believes that in order for humanity to finally win the battle against cancer, a lot more basic science needs to be done. According to her, this lack of basic science is the reason most therapies fail.
She hopes that in the near future, we can “turn cancer into a chronic disease instead of a deadly disease.” She sees a future where we can keep people alive living with cancer.
As of right now, the Schroeder lab is finishing up the research that deals with the new therapy so that they can apply for investigational new drug status with the FDA. Once granted IND, Schroeder will have permission from the FDA to begin phase I clinical trials.
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