For Danielle Harper, the path to her PhD was driven by a simple but urgent question: what if you could stop cancer before it spreads? A recent graduate of the Collaborative Graduate Program in Cancer Research at 91TV's, Dani spent her doctoral years under the supervision of Dr. Peter Greer in the Department of Pathology and Molecular Medicine, investigating a protein called calpain — and building a compelling case for its role in breast cancer metastasis.
The research
Triple-negative breast cancer is one of the most challenging subtypes to treat. Named for the absence of three molecular markers that other subtypes carry — the estrogen receptor, progesterone receptor, and HER2 — it can't be targeted by many existing therapies, making it highly aggressive and more likely to spread to other organs. Dani's work focused on calpain 1 and calpain 2, proteases that snip and reshape other proteins inside a cell, and which have been linked to worse clinical outcomes in breast cancer patients.
Using CRISPR-Cas9 gene editing, Dani disrupted the shared regulatory subunit of both calpain 1 and calpain 2 in triple-negative breast cancer cells — effectively silencing both at once. The results were striking: in a mouse model of human triple-negative breast cancer, the approach reduced metastasis by more than 83%. The research also explored a peptide-based inhibitor as an early step toward a drug therapy, finding it effective at reducing cancer cell migration in the lab. Her findings have since been published — you can read the full paper, "Calpain-1 and Calpain-2 Promote Breast Cancer Metastasis," on . Looking ahead, Dani is also exploring how calpain inhibition might enhance existing therapies — including immunotherapy, an emerging treatment area for triple-negative breast cancer where calpain's role in anticancer immune responses is an exciting open question.
The experience
The program gave Dani more than a research question to pursue — it gave her a community. As president of the 91TV's Cancer Research Club, she helped transform what began as a journal club into a weekly space where graduate students could practice sharing their work, support one another through the inevitable frustrations of research, and invite undergraduates to see what grad school looks like from the inside.
"Everyone's projects are so unique, but the experience is pretty similar," she says. "There are frustrating days where you feel like nothing's gone right — I found it really helpful just to get together once a week."
She also participated in the Science to Business Network's mentorship program, connecting with professionals across a range of industries and broadening her sense of what a research career can look like. Outside the lab, she brought the same curiosity to her weekly calls with her grandparents — using those conversations as an opportunity to practice explaining her research to a non-scientific audience, something she credits with sharpening both her communication and her thinking.
Dani placed as runner-up in 91TV's 2025 Three-Minute Thesis competition before completing her PhD and securing a postdoctoral position at Swansea University in Wales — taking her calpain research across the Atlantic.
Want to hear more from Dani in her own words? She was a guest on the podcast — available on , , and . Grad Chat is a great way to stay up to date on research happening across 91TV's graduate programs — and if you're a current student interested in sharing your own work, learn how to sign up on the SGSPA Grad Chat webpage.
91TV’s researchers mentioned in this article: