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Embryogenesis is regarded the 'miracle of life', yet numerous aspects of this process are not fully understood. As the embryo grows in the mother's womb, immune components, stem cells and microenvironmental cues cooperate among others to promote embryonic development. Evidently, these key players are frequently associated with transplantation failure and tumor growth. While the fields of transplantation and cancer biology do not overlap, both can be viewed from the perspective of an embryo. As an 'unrejected transplant' and a 'benign tumor', lessons from embryonic development may reveal features of transplants and tumors that have been overlooked. Therefore, eavesdropping at these natural complex events during pregnancy may inspire more durable approaches to arrest transplant rejection or cancer progression.

Background. Gastrosphere, an enriched cellular population with stem-like properties believed to be responsible for an escape from immune-mediated destruction. Th17 and Treg cells play a major role in gastric cancer; however, their interaction with gastrospheres remained elusive. Method. Peripheral blood mononuclear cells were isolated from healthy donors and were cultured with conditioned media of MKN-45 (parental) cells as well as gastrospheres’ conditioned media in the context of mixed lymphocyte reaction and in the presence of anti-CD3/CD28 beads. The proliferation was evaluated using CFSE staining; the percentages of CD4+CD25+FoxP3+ Treg and CD4+IL-17+ Th17 cells and IFN-γ+cells and the production of IL-17, TGF-β, and IL-10 were assessed by flow cytometry and ELISA, respectively. Finally, the cytotoxic potential of induced immune cells was measured by examining the secretion of lactate dehydrogenase from target cells. Results. The results revealed a decreased expansion of PBMCs postexposure to gastrospheres’ conditioned medium which was concomitant with an increased percentage of Th17 and an enhanced Th17 to Treg ratio. The conditioned media of gastrospheres enhanced the secretion of IL-10 and IL-17 and decreased TGF-β. Interestingly, immune cells induced by gastrospheres showed significant cytotoxicity in terms of producing IFN-γ and death induction in target cells. All these changes were related to the upregulation of IL-6, IL-10, and IL-22 in gastrospheres compared to parental cells. Conclusion. Our study showed that the condition media of gastrospheres can potentially induce Th17 with increasing in their cytotoxic effect. Based on our knowledge, the present study is the first study that emphasizes the role of gastrospheres in the induction of antitumor Th17 cells. However, it should be confirmed with complementary studies in vivo.

Failure of treatment strategies against cancers is a major issue engaging many scientists to investigate the possible resistance factors. Cancer stem cells (CSCs) subvert promising therapeutic methods by developing resistant cancers. These pluripotent cells are located in individual microenvironments called cancer niche. CSCs affect the immune cells and on the flip side, the immune cells in the cancer niche influence them. Thereby, the interaction between CSCs and immune cells in cancer niche needs to be clearly studied in order to develop novel efficient methods of immune-based cancer treatment. In this article, we review literature about the suggested methods of CSC escape from immune responses and the effect of cancer niche characteristics on the ability of CSCs to develop resistant strains of cancers. Moreover, we discuss immune-mediated tumor targeting methods and bring in trials focused on CSC targeted therapies. We aim to help physicians to reach a consensus about using CSC-targeted immunotherapy methods and emerge novel immunotherapy methods through disrupting the interaction between immune cells and CSCs in the tumor microenvironment.

Gastric cancer stem cells (GCSCs), a small population among tumor cells, are responsible for tumor initiation, development, metastasis, and recurrence. They play a crucial role in immune evasion, immunomodulation, and impairment of effector immunity and believed to be emerged to change the balance of the immune system, importantly CD4+ T cells in the chronic inflamed tumor site. However, different subtypes of innate and adaptive immune cells are involved in the formation of the immune system in the tumor microenvironment, we would look at T cells in this study. Tumor microenvironment induces differentiation of CD4+ T cells into different subsets of T cells, mainly suppressive regulatory T cells (Treg), and T helper 17 (Th17) cells, although their exact role in tumor immunity is still under debate depending on tumor types and stages. Counterbalance between Th17 and Treg cells in the gastrointestinal system result in the homeostasis and normal function of the immune system, particularly mucosal immunity. Recent data demonstrated a high infiltration of Th17 and Treg cells into the gastric tumor site and proved that tumor microenvironment might disturb the balance between Th17 and Treg. It is possible to assume an association between activation of CSCs which contribute to metastasis in late stages, and the imbalanced Th17/Treg cells observed in advanced gastric cancer patients. This review intends to clarify the importance of gastric tumor microenvironment specifically CSCs in relation to Th17/Tregs balance firstly and to highlight the relevance of imbalanced Th17/Treg subsets in determining the stages and behavior of the tumor secondly. Finally, the present study suggests a clinical approach looking at the plasticity of T cells with a focus on Th17 as a promising dedicated arm in cancer immunotherapy.