Peptídeos derivados de regiões determinantes de complementariedade (CDRs) de imunoglobulinas de camelídeos : avaliação da atividade antitumoral em modelo de melanoma murino B16F10-nex2 e mecanismos imunomodulatórios

• Ano de defesa: 2017
• Autor(a) principal: Silva, Larissa Reis da [UNIFESP]
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: por
• Instituição de defesa: Universidade Federal de São Paulo (UNIFESP)
• Palavras-chave em Português: In vitro and in vivo; Metastatic melanoma; Immunomodulation; In vitro e in vivo; Melanoma metastático; Imunomodulação
• Link de acesso: https://sucupira.capes.gov.br/sucupira/public/consultas/coleta/trabalhoConclusao/viewTrabalhoConclusao.jsf?popup=true&id_trabalho=5457390; http://repositorio.unifesp.br/handle/11600/50653

Cutaneous melanoma is a type of skin cancer that originates from transofrmed melanocytes, being one of the most aggressive malignancies, especially in white adults. There was anestimate of 5,670 cases in 2016, comprising 3000 men and 2670 women (INCA),which reflects the high frequency of primary tumors that arereadily excised surgically and themetastatic tumors that lead to death 75-90% of patients within 5 years. This is mainly due to melanoma resistance to chemotherapy and radiotherapy. Recent clinical studies have shown promising results with the use of monoclonal antibodies against immune regulatory molecules (e.g. pembrolizumab and ipilimumab) as well as inhibitors ofmutated B-RAF signaling (ex. vemurafenib) both approved by the FDA in the USA. Our laboratory has been studying bioactive synthetic peptides as an alternative to the development of antitumor agents. In particular, the studied peptides are derived from complementarity determining regions (CDRs) of monoclonal antibodies. The camelids are capable of producing antibodies having homodimeric heavy chains, with specific variable domains termed VHHs, highly resistant to changes in temperature, pH and with increased solubility. The absence of a light chain variable domain is compensated by the presence of VHCDRs that provide an antigen binding surface, with higher affinity than that of conventional human antibodies. Three peptides derived from different CDRs were synthesized and were used to assay the antitumor activity in vitro and in vivo. Systemic therapy with these peptides showed significant antitumor protection when using a metastatic murine melanoma model in syngeneic animals. However, this protection did not occur by direct peptide activity on tumor cells (induction of cytotoxicity, inhibition of cell proliferation and migration), but by the intervention of the immune system that is stimulated by these peptides, since immunodeficient animals failed to be protected. Subsequently, we verified that peptides induced activation of dendritic cells derived from bone marrow (bmDCs) for therapeutic protection against metastatic melanoma. Peptides induced nitric oxide (NO) production in bmDCs, increased expression of activation markers (CD40, CD80 and CD86), increased specific lymphocyte proliferation dependent on bmDCs previously stimulated with peptides, and increased pro-inflammatory cytokines, including IL-6, IFN-γ, TNF-α and IL 17. Although in vivo mechanisms have been partially elucidated, further studies are needed to determine the molecular mechanisms involved in the activation of bmDCs for the organization of the antitumor immune response, as well as the targets and signaling pathways involved. In conclusion, this work presents three new peptides derived from camelid CDRs with immunomodulatory antitumor activities in vitro and in vivo, which emerge as important candidates for the immunotherapy of metastatic melanoma.