RESUMEN
BACKGROUND: We have recently reported that chemotherapeutic agents in ultra low noncytotoxic concentrations may block the ability of tumor cells to suppress functional activation of dendritic cells (DCs). METHODS: HCT-116 human colon cancer cells were treated with 0.5 nM paclitaxel (PAC) or 2 nM doxorubicin (DOX) with the aim of defining the immunogenic changes induced by ultra low noncytotoxic concentrations of antineoplastic chemotherapeutic agents. Genetic alterations were screened by DNA microarray that revealed increased expression of genes involved in antigen processing and presentation, including the heat-shock protein, calmodulin, and proteasome 26 genes. As the proteins encoded by these genes are involved in the cytosolic route of antigen processing machinery, we next evaluated whether PAC and DOX in noncytotoxic concentrations changed expression of MHC class I antigen processing machinery (APM) components in three different colon cancer cell lines. RESULTS: Our results showed that PAC and DOX increased the intracellular expression of APM proteins, including calmodulin, LMP2, LMP7, TAP1 and tapasin. The biological significance of modulation of antigen processing and presentation proteins in tumor cells by ultra low nontoxic concentrations of chemotherapeutic drugs was revealed when non-treated and treated tumor cells were used as a source of tumor antigens for the generation of tumor-specific cytotoxic T cells (CTLs) in vitro. We demonstrated that (i) DCs that engulf tumor cells pretreated with noncytotoxic concentrations of chemotherapeutic agents induced CTLs with a higher cytotoxic potential than DCs loaded with nontreated tumor cells, and (ii) CTLs induced by tumor lysate-pulsed DCs killed live tumor cells more efficiently if these tumor cells were pretreated with noncytotoxic concentrations of chemotherapeutic drugs. CONCLUSIONS: These results demonstrate that chemomodulation of human tumor cells with noncytotoxic concentrations of chemotherapeutic agents increases tumor immunogenicity and results in the generation of more efficient DC vaccines and CTLs, which can be used for cell-based anticancer immunotherapies.
Asunto(s)
Antineoplásicos/farmacología , Citotoxicidad Inmunológica/efectos de los fármacos , Células Dendríticas/inmunología , Linfocitos T Citotóxicos/inmunología , Transportador de Casetes de Unión a ATP, Subfamilia B, Miembro 2 , Transportadoras de Casetes de Unión a ATP/genética , Presentación de Antígeno/genética , Calmodulina/genética , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Técnicas de Cocultivo , Neoplasias del Colon/genética , Neoplasias del Colon/inmunología , Neoplasias del Colon/patología , Cisteína Endopeptidasas/genética , Citotoxicidad Inmunológica/genética , Células Dendríticas/citología , Células Dendríticas/metabolismo , Relación Dosis-Respuesta a Droga , Doxorrubicina/farmacología , Perfilación de la Expresión Génica , Regulación Neoplásica de la Expresión Génica/efectos de los fármacos , Células HCT116 , Células HT29 , Humanos , Proteínas de Transporte de Membrana/genética , Análisis de Secuencia por Matrices de Oligonucleótidos , Paclitaxel/farmacología , Complejo de la Endopetidasa Proteasomal/genética , Linfocitos T Citotóxicos/citología , Linfocitos T Citotóxicos/metabolismoRESUMEN
The dose-delivery schedule of conventional chemotherapy, which determines its efficacy and toxicity, is based on the maximum tolerated dose. This strategy has lead to cure and disease control in a significant number of patients but is associated with significant short-term and long-term toxicity. Recent data demonstrate that moderately low-dose chemotherapy may be efficiently combined with immunotherapy, particularly with dendritic cell (DC) vaccines, to improve the overall therapeutic efficacy. However, the direct effects of low and ultra-low concentrations on DCs are still unknown. Here we characterized the effects of low noncytotoxic concentrations of different classes of chemotherapeutic agents on human DCs in vitro. DCs treated with antimicrotubule agents vincristine, vinblastine, and paclitaxel or with antimetabolites 5-aza-2-deoxycytidine and methotrexate, showed increased expression of CD83 and CD40 molecules. Expression of CD80 on DCs was also stimulated by vinblastine, paclitaxel, azacytidine, methotrexate, and mitomycin C used in low nontoxic concentrations. Furthermore, 5-aza-2-deoxycytidine, methotrexate, and mitomycin C increased the ability of human DCs to stimulate proliferation of allogeneic T lymphocytes. Thus, our data demonstrate for the first time that in low noncytotoxic concentrations chemotherapeutic agents do not induce apoptosis of DCs, but directly enhance DC maturation and function. This suggests that modulation of human DCs by noncytotoxic concentrations of antineoplastic drugs, i.e. chemomodulation, might represent a novel approach for up-regulation of functional activity of resident DCs in the tumor microenvironment or improving the efficacy of DCs prepared ex vivo for subsequent vaccinations.