Dendritic Cells Transfected with a DNA Construct Encoding Tumour‐associated Antigen Epitopes Induce a Cytotoxic Immune Response Against Autologous Tumour Cells in a Culture of Mononuclear Cells from Colorectal Cancer Patients

Abstract

Significant effort has been devoted to developing effective cancer vaccines based on dendritic cells (DCs) loaded with various tumour antigens, including DNA constructs that carry sequences of tumour-associated antigens (TAAs). Such vaccines efficiently and selectively activate the T cell immune response. In this study, we describe a method to induce an antitumour immune response in mononuclear cell (MNC) cultures from colorectal cancer patients using DNAtransfected DCs encoding TAA epitopes of carcinoembryonic antigen, epithelial cell adhesion molecule and mucin 4. DCs were obtained from peripheral blood monocytes of colorectal cancer patients. Magnetic-assisted transfection was used to deliver the genetic constructs to DCs. To assess the potency of the immune response, the antitumour cytotoxic response was assessed by lymphocyte intracellular perforin and the MNC cytotoxic activity against autologous tumour cells. We showed that polyepitope DNA-transfected DCs enhanced MNC antitumour activity, increasing tumour cell death and the percentage of perforinpositive lymphocytes. In addition, DNA-transfected DCs elicited a cytotoxic response that was as efficient as that of tumour lysate-loaded DCs. Taken together, the data suggest that it is feasible to induce an antitumour immune response in colorectal MNCs using transfected DCs. Thus, the DNA construct reported in this study may potentially be used in therapeutic and prophylactic DC-based vaccines.

Use of antigen‑primed dendritic cells for inducing antitumor immune responses in�vitro in patients with non‑small cell lung cancer

“…To date, there are a number of approaches for generating DCs in vitro, including preparation of DCs from peripheral blood monocytes and bone marrow progenitors (CD34 + cells) (18). Furthermore, a wide range of factors may be used for differentiation and maturation of DCs (GM-CSF, IL-4, interferon-α, IL-2, IL-6, IL-15, TGF-α, stem cell factor, FLT-3 ligand and prostaglandin E2) that may facilitate, in a combination or individually, the generation of DCs from monocytes or CD34 + cells (19)(20)(21)(22)(23). The present study suggested that there is some danger in using numerous factors for differentiation and maturation of DCs that can lead to the production of DC subsets with a variety of phenotypes and functions.…”

“…Tumor cell lysates, tumor cell RNA, recombinant proteins of tumor-associated antigens, and DNA constructs encoding tumor-associated antigens have been used as antigens (21,30,31). Loading DCs with a tumor lysate enables presentation of a range of tumor antigens from a patient (32).…”

Modern strategies and capabilities for activation of the immune response against tumor cells

“…However, autologous tumor cell lysate antigens presented to DCs stimulate specific CTL responses. 31,32,[36][37][38] …”

“…[31][32][33] The first step in this process is providing DCs with tumor antigens. 34 Regardless of the method of tumor antigen delivery, there is convincing evidence for the induction of a protective and therapeutic antitumor immune response without specific toxicity.…”

“…32,62 Furthermore, we demonstrated that DCs transfected with a polyepitopic DNA construct encoding epitopes of TAAs (CEA, MUC4, and epithelial cell adhesion molecules) stimulated the cytotoxic activity of mononuclear cells in colorectal cancer patients against autologous tumor cells and facilitated perforin accumulation in peripheral blood mononuclear cells. 31 In addition, a plasmid carrying TAA polyepitopes acts as a natural adjuvant (because of the presence of non-methylated CG sequences) and stimulates innate immunity.…”