Imunoterapia com IL-2 e TRAIL expressas por Salmonella recombinante contra o câncer de bexiga

Abstract

IL-2 and TRAIL are therapeutic agents known for their antitumor role, but they can be rapidly cleared by the body or be toxic, compromising their function. To reverse this impasse, the synthesis of these agents by living bacteria directly in the tumor is a viable approach, due to the preference of bacteria to infect tumor cells. This happens due to the high nutrient grid in this microenvironment and escape from the protective action of immune cells since solid tumors are ischemic and have regions of hypoxia. In this context, Salmonella represents a promising live vector for delivering molecules with an antitumor role. In this context, Salmonella represents a promising live vector for delivering molecules with an antitumor role. This study investigated the effects of IL-2, TRAIL and MIX of proteins expressed by recombinant Salmonella, strain SL3261, which contains a plasmid for the gene sequence of IL-2 and TRAIL, in bladder tumor cells in in vitro and in vivo models. The murine MB49 and human RT4 bladder cancer cell lines and C57BL/6 female mice were used. In in vitro tests, the cells were exposed for 24 and 48 hours to these proteins and the analyzes were performed by flow cytometry, ELISA, dyes and fluorescent antibodies to detect several cellular parameters: viability, morphology, recovery, nitric oxide synthesis, secretion of LDH, production of inflammatory cytokines and apoptosis. For in vivo test, a bladder tumor was induced in female mice by inoculation of MB49 cells followed by intravesical treatment, with subsequent analysis of survival, bladder weight, tumor regression, cell profile, cytokine release and biodistribution of bacterial strains. The data obtained indicate that both agents are cytotoxic for the tumor cell, as they cause a decrease in cell viability, modification of its own morphology and induction of apoptosis in both MB49 and RT4. This effect is caused by the activation of the enzyme iNOS by IL-2, which induces the synthesis of nitric oxide with consequent activation of genes that determine DNA degradation, and by the activation of the Caspase family by TRAIL, leading to apoptosis. In the in vivo tests, however, there was marked tumor regression, activation of the immune response due to the action of proteins, cell recruitment against tumor cells without causing damage to healthy tissues with an effect only on the tumor. Therefore, IL-2 and TRAIL expressed and conveyed by SL3261 have promising potential in the therapy of bladder cancer and that the proteins present synergism and that the MIX is more effective.