Imunoterapia com células NK: uma nova abordagem para o cancro da bexiga

A existência de células cancerígenas com características semelhantes às das células estaminais normais constitui um dos principais obstáculos ao sucesso das terapias anticancerígenas. Estas células, conhecidas como Cancer Stem Cells (CSCs), já identificadas em muitas neoplasias incluindo o carcinoma da bexiga, têm uma elevada capacidade de autorrenovação e potencial tumorigénico. Atualmente, as abordagens terapêuticas em vigor não conseguem eliminar as CSCs podendo até favorecer a seleção de clones resistentes e a sua expansão, o que aumenta o risco de recidivas e progressão tumoral para estadios mais invasivos. Neste estudo, avaliámos o potencial da aplicação de uma nova abordagem terapêutica baseada na imunoterapia adotiva com células Natural Killer (NK) na eliminação das CSCs no carcinoma da bexiga e o seu impacto na progressão tumoral, utilizando modelos in vitro e in vivo. Os nossos resultados mostraram que células NK isoladas de dadores saudáveis e ativadas com um cocktail de citocinas (IL-2/IL-15) são eficazes na indução de uma resposta anti-tumoral contra as células do carcinoma da bexiga. Contrariamente à quimioterapia, as células NK ativadas demonstraram um elevado potencial citotóxico tanto para as células mais diferenciadas como para as CSCs. Adicionalmente, as células NK induziram uma alteração no fenótipo das CSCs para um estado mais diferenciado, tornando-as mais suscetíveis aos efeitos citotóxicos da cisplatina, realçando os benefícios de uma possível terapia combinada. Nos estudos in vivo num modelo animal em ratinho, a administração local das células NK (via transuretral), favoreceu a infiltração e subsequente atividade citolítica das células NK, tendo-se observado uma redução da massa tumoral superior a 80%. Uma vez que as células NK são igualmente eficazes na eliminação das CSCs e das células mais diferenciadas, a sua administração por via intravesical poderá ser considerada como uma promissora estratégia para o tratamento do carcinoma da bexiga, per se ou de forma complementar às opções terapêuticas atuais.

Autores e Afiliações:

Margarida Ferreira-Teixeira ^1,2, Daniela Paiva-Oliveira ^1,2, Belmiro Parada ^1,3, Vera Alves ^4, Vitor Sousa ^5,6, Obinna Chijioke ^7, Christian Münz ⁷, Flávio Reis ^1,2, Paulo Rodrigues-Santos ^4,8* and Célia Gomes ^1,2*

¹ Laboratory of Pharmacology and Experimental Therapeutics, Institute for Biomedical Imaging and Life Sciences (IBILI), Faculty of Medicine, University of Coimbra, Coimbra, Portugal

² CNC.IBILI, University of Coimbra, Coimbra, Portugal

³ Urology and Renal Transplantation Department, Coimbra University Hospital Centre (CHUC), Coimbra, Portugal

⁴ Institute of Immunology, Faculty of Medicine, University of Coimbra, Coimbra, Portugal

⁵ Service of Anatomical Pathology, Coimbra University Hospital Centre (CHUC), Coimbra, Portugal

⁶ Institute of Anatomical and Molecular Pathology, Faculty of Medicine, University of Coimbra, Coimbra, Portugal

⁷ Viral Immunobiology, Institute of Experimental Immunology, University of Zürich, Zürich, Switzerland

⁸ Immunology and Oncology Laboratory, Center for Neurosciences and Cell Biology (CNC), University of Coimbra, Coimbra, Portugal

Abstract:

Background: High-grade non-muscle invasive bladder cancer (NMIBC) has a high risk of recurrence and progression to muscle-invasive forms, which seems to be largely related to the presence of tumorigenic stem-like cell populations that are refractory to conventional therapies. Here, we evaluated the therapeutic potential of Natural Killer (NK) cell-based adoptive immunotherapy against chemoresistant bladder cancer stem-like cells (CSCs) in a pre-clinical relevant model, using NK cells from healthy donors and NMIBC patients. Methods: Cytokine-activated NK cells from healthy donors and from high-grade NMIBC patients were phenotypically characterized and assayed in vitro against stem-like and bulk differentiated bladder cancer cells. Stem-like cells were isolated from two bladder cancer cell lines using the sphere-forming assay. The in vivo therapeutic efficacy was evaluated in mice bearing a CSC-induced orthotopic bladder cancer. Animals were treated by intravesical instillation of interleukin-activated NK cells. Tumor response was evaluated longitudinally by non-invasive bioluminescence imaging. Results: NK cells from healthy donors upon activation with IL-2 and IL-15 kills indiscriminately both stem-like and differentiated tumor cells via stress ligand recognition. In addition to cell killing, NK cells shifted CSCs towards a more differentiated phenotype, rendering them more susceptible to cisplatin, highlighting the benefits of a possible combined therapy. On the contrary, NK cells from NMIBC patients displayed a low density on NK cytotoxicity receptors, adhesion molecules and a more immature phenotype, losing their ability to kill and drive differentiation of CSCs. The local administration, via the transurethral route, of activated NK cells from healthy donors provides an efficient tumor infiltration and a subsequent robust tumoricidal activity against bladder cancer with high selective cytolytic activity against CSCs, leading to a dramatic reduction in tumor burden from 80 % to complete remission. Conclusion: Although pre-clinical, our results strongly suggest that an immunotherapeutic strategy using allogeneic activated NK cells from healthy donors is effective and should be exploited as a complementary therapeutic strategy in high-risk NMIBC patients to prevent tumor recurrence and progression.

Revista: BMC Medicine (2016) 14:163

Link: https://www.ncbi.nlm.nih.gov/pubmed/27769244