The Role of a Natural Amphibian Skin-Based Peptide, Ranatensin, in Pancreatic Cancers Expressing Dopamine D2 Receptors

Simple Summary Cancer is one of the most problematic issues worldwide, as it still requires effective therapy. Unfortunately, clinically available cancer-specific medications result in serious side effects. This is also true for pancreatic cancer which additionally is well-known for difficulties in the treatment. Therefore, the aim of the study was to evaluate the biological activity, in terms of anticancer effects, of ranatensin (RAN), a naturally existing bombesin-like peptide. For the first time, we characterized the peptide as a dopaminergic system ligand. However, despite the presence of dopamine receptors in pancreatic cancer cell lines used, RAN was found to affect cancer cells possibly through different receptors since RAN’s impact on pancreatic cancer cells was not correlated with their expression level of DRD2. Nevertheless, this peptide may serve as a potential useful agent with therapeutic efficacy in cancers expressing DRD2 receptors, for which DRD2 antagonism is crucial to produce antitumor effects. Abstract Despite the progress in early diagnostic and available treatments, pancreatic cancer remains one of the deadliest cancers. Therefore, there is an urgent need for novel anticancer agents with a good safety profile, particularly in terms of possible side-effects. Recently dopaminergic receptors have been widely studied as they were proven to play an important role in cancer progression. Although various synthetic compounds are known for their interactions with the dopaminergic system, peptides have recently made a great comeback. This is because peptides are relatively safe, easy to correct in terms of the improvement of their physicochemical and biological properties, and easy to predict. This paper aims to evaluate the anticancer activity of a naturally existing peptide—ranatensin, toward three different pancreatic cancer cell lines. Additionally, since there is no sufficient information confirming the exact character of the interaction between ranatensin and dopaminergic receptors, we provide, for the first time, binding properties of the compound to such receptors.