New compound shows promise against aromatase inhibitor-resistant breast cancer

A new research paper was published in Volume 16 of Oncotarget on July 29, 2025, titled "PCAIs stimulate MAPK, PI3K/AKT pathways and ROS-Mediated apoptosis in aromatase inhibitor-resistant breast cancer cells while disrupting actin filaments and focal adhesion."

In this study, led by first author Jassy Mary S. Lazarte and corresponding author Nazarius S. Lamango from Florida A&M University College of Pharmacy and Pharmaceutical Sciences, researchers investigated a new class of compounds called polyisoprenylated cysteinyl amide inhibitors (PCAIs) as a potential treatment for aromatase inhibitor (AI) therapy resistant breast cancer. Aromatase inhibitors are a common treatment for estrogen receptor-positive (ER+) breast cancer, but many patients eventually develop resistance, leaving fewer therapeutic options.

The study focused on a PCAI compound called NSL-YHJ-2-27, which was tested in long-term letrozole-treated breast cancer cells (LTLT-Ca), an experimental model of AI therapy resistance. NSL-YHJ-2-27 activated two major signaling pathways, MAPK and PI3K/AKT. Although these pathways typically support cancer cell survival, their overstimulation by PCAIs led to increased oxidative stress, damaging the cells and inducing cell death by apoptosis. The compound also reduced levels of RAC1 and CDC42, proteins involved in maintaining cell shape and movement. These alterations resulted in cytoskeletal disruption and reduced structural integrity, making the cancer cells more vulnerable and less capable of spreading. Importantly, the effects of NSL-YHJ-2-27 persisted after the compound was removed, suggesting long-term control over AI resistant cancer cells may be possible.

"PCAIs inhibited cell proliferation and colony formation by 95% and 74%, respectively, increased active caspase 7 and BAX 1.5-fold and 56%, respectively. NSL-YHJ-2-27 (10 μM) induced LTLT-Ca spheroid degeneration by 61%."

As a new class of targeted molecules, PCAIs represent an innovative approach distinct from traditional endocrine therapies. Their ability to affect multiple cellular mechanisms simultaneously makes them promising candidates for future drug development.

Overall, this study presents a promising new approach for treating AI therapy-resistant breast cancer. By targeting cellular pathways that support survival and mobility, PCAIs like NSL-YHJ-2-27 could provide a novel strategy to manage advanced or resistant forms of the disease. Further research, including in vivo studies and clinical trials, will be essential to confirm these findings and evaluate their therapeutic potential.