Certain chemotherapy and radiotherapy regimens induce Immunogenic Cell Death (ICD) in tumor cells, contributing to the control of tumors by T cells. Markers of ICD includes HMGB-1 and ATP, expression of phosphatidylserine and Calreticulin (CRT) on the surface of apoptotic cells. ICD promotes the maturation of dendritic cells (DC) and the further activation of CTLs. This work was oriented to the implementation of an in vitro screening system of tumor cells, to induce ICD for their possible use in the immunotherapy of cancer in the future.
Tumor lines (REH, CRL2338 (Her2/neu +++) and KATO III) were treated in vitro with various agents used in antitumor therapy (Carboplatin, Gemcitabine, Doxorubicin, Oxaliplatin, Cyclophosphamide, and Paclitaxel). We established the in vitro conditions (time and concentration) of the treatments to characterize the type of death induced by these agents.
ICD induction in the tumor cells were examined by the capacity of treated tumor cells to elicit the maturation of DC and expansion of activated CTLs. The treatment with different agents evidenced various degree of susceptibility of these cells to ICD inducers. These variations were reflected by different activation profiles of Caspases 3,7 and 8. In some tumor cell types, we detected an alteration of the mitochondrial membrane potential status and alteration of the cell cycle. Finally, we observed endoplasmic reticulum stress; and expression of Annexin V, CRT, HMGB-1 and ATP and others like ROS, NF-kB, COX-2, PPAR-y. The evaluation of immune recognition of treated cells showed an important role in the activation of the innate and adaptive response. This was evidenced by the stimulation of DCs such as phagocytosis, homing, production of Il-12 and cross-presentation to CD8+ T cells as well as activation of CD8 T lymphocytes specific for tumor antigens.
In summary our results led us to conclude that induction of ICD in vitro in tumor cells emerges as a useful tool for the selection of tumor cells as possible vaccines against different tumors that efficiently stimulate the functions of APCs and the activation of antitumor CTLs.
Universidad Nacional de Colombia
Universidad Nacional de Colombia y Fundación Salud de los Andes
All authors have declared no conflicts of interest.