Targeting Peptidergic Systems for Melanoma Treatment

Melanoma is a heterogeneous, complex and aggressive disease that, despite recent advances in molecular-targeted drugs and molecular and genetic analysis, represents approximately 65% of skin cancer deaths, and unfortunately survival dramatically decreases in melanoma stages III/IV. In young people there is an increased incidence of developing melanoma; hence new therapeutic strategies must be urgently investigated. Peptidergic systems play a crucial role in these strategies to fight melanoma. The scope of this review is to show the enormous potential of targeting peptidergic systems alone or in combination therapy with standard therapeutic strategies currently used in clinical practice to treat melanoma. In this sense, key points such as peptidergic systems and anti-melanoma treatments, oncogenic/anti-melanoma peptides, peptide receptors, peptidergic systems, melanoma risk and immune system relationships, clinical relevance, peptidergic systems and delivery strategies in melanoma will be discussed. Peptides exert oncogenic, anti-melanoma and dual oncogenic and anti-melanoma effects in melanoma, showing a high functional complexity in regulating melanoma development. A plethora of anti-melanoma strategies have been developed or repurposed for potential clinical applications, including peptide/peptide receptor antibodies, peptide receptor antagonists or agonists, enzyme inhibitors, CAR-macrophages, microRNAs and vaccines. Strategies for peptide delivery and protection from enzymatic degradation have also been developed. Some of the previous anti-melanoma strategies are based on the expression/overexpression of peptide receptors in melanoma cells which is crucial for diagnosis, melanoma risk and progression and metastasis development and for the application of more specific and safer anti-melanoma strategies. A meticulous and in-depth study of the peptidergic systems may help to understand how peptidergic systems regulate melanoma progression and shed light on possible therapeutic applications that can be applied in clinical practice. This review shows the enormous potential of targeting peptidergic systems alone or in combination therapy with standard therapeutic strategies currently used in clinical practice to treat melanoma. The benefits to be gained from these studies will be enormous because the peptidergic systems are promising antitumor targets in melanoma, based on the numerous anti-melanoma strategies that have been developed until now.