Cancer stem-like cells (CSCs)/cancer-initiating cells (CICs) are defined as a small population of cancer cells that have the properties of (i) high tumor-initiating ability, (ii) self-renewal and (iii) differentiation. CSCs/CICs are known to be resistant to several treatments including chemotherapy and radiotherapy, thus CSCs/CICs are thought to be one of mechanisms related to recurrence of disease and distant metastasis. In this presentation, we present the tumor-associated antigens (TAAs) which is preferentially expressed in CSCs/CICs (CSC antigen) and potency of cancer stem cell targeting immunotherapy using CSC antigens.Methods and results
CSCs/CICs were isolated as side population (SP) cells by using cell sorter, and we found that known tumor-associated antigens (TAAs) could be classified into three groups according to the expression pattern in SP and non-CSCs/CICs (main population (MP) cells); (i) CSC antigens (expressed preferentially in SP cells), (ii) shared antigens (expressed in both SP and MP cells) and (iii) non-CSC antigens (expressed preferentially in MP cells). We compared the potency of CSC antigens, shared antigens and non-CSC antigens by DNA vaccination model and CTL adoptive transfer model, and found that CSC antigens might be the most potent compared with shared antigens and non-CSC antigens.Conclusion
These observations indicate that CSCs/CICs targeting immunotherapy is feasible and antigen expression in CSC/CIC population might be essential to achieve anti-tumor effect in cancer immunotherapy.