Dipeptide PA3264 derived from rare and endangered Squama Manis is a novel bioactive peptide for the treatment of triple-negative breast cancer.

Background: Squama Manis is a valuable traditional Chinese medicine with a long history of medicinal use in the treatment of breast-related diseases. However, owing to the excessive exploitation and utilization of the resources, Squama Manis has been included in the list of rare and endangered wild animals. The conservation of the resources of Squama Manis and continuing its clinical application has become an urgent problem, and the search for small-molecule substitutes for Squama Manis is an effective way to achieve this goal. Previous studies have identified PA3264 as a possible active ingredient in Squama Manis. In this study, we systematically investigated the pharmacological effects and mechanisms of PA3264 in the treatment of triple-negative breast cancer (TNBC), a representative breast-related disease.

Methods: Cell viability and colony formation assays were performed after treatment with the target dipeptide PA3264 in vitro. Next, 4T1 orthotopic tumors and humanized PBMC-CDX mouse models were generated to examine the antitumor effect of PA3264 in vivo. Transcriptome sequencing and molecular docking experiments were performed to predict pathways to function. Western blotting and quantitative real-time PCR were used to validate the molecular mechanisms underlying the anticancer effects of PA3264.

Results: PA3264 significantly inhibited cell viability and migration of breast cancer cells in vitro. Furthermore, PA3264 suppressed the tumor size and reduced the tumor weight in vivo. Finally, it was verified that PA3264 prevented the progression of breast cancer by inhibiting the PI3K/AKT/NF-κB pathway, causing cell cycle arrest, and promoting apoptosis.

Conclusions: This study elucidated that PA3264 derived from rare and endangered Squama Manis was a novel bioactive peptide for treating triple-negative breast cancer from a scientific research perspective.