Heat Shock Proteins Regulating Toll-like Receptors and the Immune System could be a Novel Therapeutic Target for Melanoma

Melanoma is a serious type of skin cancer, which develops in melanocyte cells. Although it is less common than some other skin cancers, it can be far more dangerous if not treated at an early stage because of its ability to spread rapidly to other organs. Heat shock proteins (HSP) are intracellular molecular chaperones of naive proteins, which are induced in response to stressful conditions. HSP is released into the extracellular milieu and binds to Toll-like receptors (TLRs) to regulate immune responses, such as cytokine and chemokine release. HSPs can release and bind to tumor-specific antigens, with cross-presentation of major histocompatibility complex (MHC) class I antigens. TLRs are innate immune system receptors, involved in the melanoma growth pathway through HSP activation. Melanocytes express TLR4 and TLR9 to modulate immune responses. Many TLR ligands are considered as proper adjuvant candidates, as they can activate dendritic cells. Targeting some TLRs, such as TLR7 and TLR9, is an available option for treating melanoma. In this review, we aimed to determine the relationship between TLRs and HSP groups in melanoma.