Dendritic cells loaded with exosomes derived from cancer stem cell‐enriched spheroids as a potential immunotherapeutic option

Abstract

Cancer stem cells (CSCs) are responsible for therapeutic resistance and recurrence in colorectal cancer. Despite advances in immunotherapy, the inability to specifically eradicate CSCs has led to treatment failure. Hence, identification of appropriate antigen sources is a major challenge in designing dendritic cell (DC)‐based therapeutic strategies against CSCs. Here, in an in vitro model using the HT‐29 colon cancer cell line, we explored the efficacy of DCs loaded with exosomes derived from CSC‐enriched colonospheres (CSCenr‐EXOs) as an antigen source in activating CSC‐specific T‐cell responses. HT‐29 lysate, HT‐29‐EXOs and CSCenr lysate were independently assessed as separate antigen sources. Having confirmed CSCs enrichment in spheroids, CSCenr‐EXOs were purified and characterized, and their impact on DC maturation was investigated. Finally, the impact of the antigen‐pulsed DCs on the proliferation rate and also spheroid destructive capacity of autologous T cells was assessed. CSCenr‐EXOs similar to other antigen groups had no suppressive/negative impacts on phenotypic maturation of DCs as judged by the expression level of costimulatory molecules. Notably, similar to CSCenr lysate, CSCenr‐EXOs significantly increased the IL‐12/IL‐10 ratio in supernatants of mature DCs. CSCenr‐EXO‐loaded DCs effectively promoted T‐cell proliferation. Importantly, T cells stimulated with CSCenr‐EXOs disrupted spheroids' structure. Thus, CSCenr‐EXOs present a novel and promising antigen source that in combination with conventional tumour bulk‐derived antigens should be further explored in pre‐clinical immunotherapeutic settings for the efficacy in hampering recurrence and metastatic spread.

Overexpression of DDIT4 and TPTEP1 are associated with metastasis and advanced stages in colorectal cancer patients: a study utilizing bioinformatics prediction and experimental validation

“…The HT-29 cancer cells were cultured in DMEM/High glucose medium (Gibco, Germany) supplemented with 10% fetal bovine serum (Gibco, Germany), 1% non‐essential amino acids (Gibco, Germany), 2 mM l -glutamine (Gibco, Germany) and 1% Penicillin–Streptomycin (Biowest, France) at 37 °C in 5% CO 2 and 95% humidified incubator. Colorectal CSC-enriched spheroids were generated using hanging droplet technique of HT-29 cancer cells descripted earlier [ 63 ]. Spheroid culture medium included DMEM/F12 (Gibco, Germany), supplemented with 2% B27 (Gibco, Germany), 10 ng/ml of basic fibroblast growth factor (bFGF), 20 ng/ml epidermal growth factor (EGF) (PeproTech, USA), 1% nonessential amino acids, 2 mM l -glutamine, and 1% Penicillin–Streptomycin.…”

RAB27A‐dependent release of exosomes by liver cancer stem cells induces Nanog expression in their differentiated progenies and confers regorafenib resistance

“…8 Therefore, simultaneously targeting existing CSCs and de novo generation of CSCs is pivotal to eliminate tumors. [20][21][22] Previous studies have shown that CSC-derived exosomes play a role in the acquired resistance of tumor cells to chemotherapeutic agents. 13 In this study, we found that exosomes derived from LCSCs increase the stemness of differentiated cancer cells by upregulating expression of NANOG, enhancing resistance to regorafenib.…”

Immune evader cancer stem cells direct the perspective approaches to cancer immunotherapy

“…The DCs-based vaccines have been developed as a promising and effective strategy to facilitate CSC eradication, and in two examples, DCs loaded with CSCs-lysate [ 72 ] or CSCs-derived exosomes [ 73 ] have shown promising preclinical immunotherapeutic outcomes. However, defects in MHC-I and the presence of tolerogenic T cells recognizing TAAs result in the low immunogenicity of these antigens.…”