title: Chemotherapeutic agents in low noncytotoxic concentrations increase immunogenicity of human colon cancer cells.
abstract: 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.
authors.affiliation: Department of Microbiology and Immunology, Institute of Biosciences, São Paulo State University, Botucatu, SP, Brazil.
authors.forename: Ramon
authors.initials: R
authors.lastname: Kaneno
authors.forename: Galina V
authors.initials: GV
authors.lastname: Shurin
authors.forename: Felipe M
authors.initials: FM
authors.lastname: Kaneno
authors.forename: Hiam
authors.initials: H
authors.lastname: Naiditch
authors.forename: Jianhua
authors.initials: J
authors.lastname: Luo
authors.forename: Michael R
authors.initials: MR
authors.lastname: Shurin
mesh_terms: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters / Q000235:genetics; D017951:Antigen Presentation / Q000235:genetics; D000970:Antineoplastic Agents / Q000494:pharmacology*; D002147:Calmodulin / Q000235:genetics; D002470:Cell Survival / Q000187:drug effects; D002478:Cells, Cultured; D018920:Coculture Techniques; D003110:Colonic Neoplasms / Q000235:genetics / Q000276:immunology / Q000473:pathology; D003546:Cysteine Endopeptidases / Q000235:genetics; D003602:Cytotoxicity, Immunologic / Q000187:drug effects* / Q000235:genetics; D003713:Dendritic Cells / Q000166:cytology / Q000276:immunology* / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004317:Doxorubicin / Q000494:pharmacology; D020869:Gene Expression Profiling; D015972:Gene Expression Regulation, Neoplastic / Q000187:drug effects; D045325:HCT116 Cells; D019073:HT29 Cells; D006801:Humans; D026901:Membrane Transport Proteins / Q000235:genetics; D020411:Oligonucleotide Array Sequence Analysis; D017239:Paclitaxel / Q000494:pharmacology; D046988:Proteasome Endopeptidase Complex / Q000235:genetics; D013602:T-Lymphocytes, Cytotoxic / Q000166:cytology / Q000276:immunology* / Q000378:metabolism
chemical_list: D000071181:ATP Binding Cassette Transporter, Subfamily B, Member 2; D018528:ATP-Binding Cassette Transporters; D000970:Antineoplastic Agents; D002147:Calmodulin; D026901:Membrane Transport Proteins; C073119:TAP1 protein, human; C107762:tapasin; C071313:LMP-2 protein; D004317:Doxorubicin; D003546:Cysteine Endopeptidases; C077436:LMP7 protein; D046988:Proteasome Endopeptidase Complex; D017239:Paclitaxel