Tumor heterogeneity is a hallmark of cancer cells, and it is believed that tumor heterogeneity is partly due to asymmetric cell division of cancer stem cells. The identification of cancer stem cells within cancer cell populations suggests that cancer stem cells may be the key to tumor cell heterogeneity and resistance to drugs and radiation. Cancer stem cells have been shown to express specifi c cell surface markers, but functional analysis of these markers has been slow due to the very low percentage of cancer stem cells in the tumor cell population. CD133 is a cancer stem cell marker that mainly localizes to the plasma membrane in hematopoietic/neural stem cells and cancer stem cells. In 2019, we reported that CD133 is downregulated by endocytosis, transported to the centrosome, and inhibited autophagy, thereby maintaining cancer cells in an undifferentiated state. Recently, we also found that the distribution of CD133 endosomes, which localized to the centrosome, is highly heterogeneous and that cells with various autophagy activities are generated by asymmetric cell division. Here, we will introduce the relationship between autophagy regulation and asymmetric cell division mediated by CD133. Cancer stem cells have been shown to express specifi c cell surface markers, but functional analysis of these markers has been slow due to the very low percentage of cancer stem cells in the tumor cell population. CD133 is a cancer stem cell marker that mainly localizes to the plasma membrane in hematopoietic/neural stem cells and cancer stem cells. In 2019, we reported that CD133 is downregulated by endocytosis, transported to the centrosome, and inhibited autophagy, thereby maintaining cancer cells in an undifferentiated state. Recently, we also found that the distribution of CD133 endosomes, which localized to the centrosome, is highly heterogeneous and that cells with various autophagy activities are generated by asymmetric cell division. Here, we will introduce the relationship between autophagy regulation and asymmetric cell division mediated by CD133.

Although it is held that pro-infl ammatory changes precede the onset of breast cancer, the underlying mechanisms remain obscure. Here, we demonstrate that FRS2β, an adaptor protein expressed in a small subset of mammary epithelial cells, triggers the pro-inflammatory changes that induce stroma in precancerous mammary tissues and is responsible for the disease onset. FRS2β-deficiency in a mouse mammary tumor virus (MMTV)-ErbB2 genetic background markedly attenuated mammary tumorigenesis. FRS2β (+/+) tumors contained ample stroma, on the other hand, very little stroma was observed in FRS2β (-/-) tumors, suggesting that FRS2β is required for the formation of tumor stroma. Tumor cells derived from MMTV-ErbB2 mice failed to form tumors when they were inoculated in the FRS2β-defi cient precancerous mammary tissues, indicating that FRS2β plays essential role in mammary tumorigenesis. We also demonstrated that co-localization of FRS2β and the NEMO subunit of the IkB kinase (IKK) complex in early endosomes led to activation of nuclear factor-κB (NF-κB), a master regulator of infl ammation. Moreover, inhibition of the activities of the NF-κB-induced cytokines, CXC chemokine ligand (CXCL)12 and insulin-like growth factor (IGF)1, abrogated tumorigenesis, indicating that the production of IGF1 and CXCL12 in premalignant mammary tissues creates a cytokine-enriched microenvironment that is necessary for mammary tumorigenesis. Human breast cancer tissues that express higher levels of FRS2β contain more stroma. Furthermore, patients with higher expression levels of FRS2βin breast cancer tissues had poorer prognosis. Collectively, the elucidation of the FRS2β-NF-κB axis uncovers the unknown molecular link between the pro-infl ammatory changes and the onset of breast cancer.

Background

Although advances in immunotherapy have increased awareness of the importance of immunity in malignancy, it has not yet been fully investigated in pediatric myeloid malignancies. In this study, we conducted mass cytometric analysis on samples from pediatric patients with myeloid malignancies.

Method

Cryopreserved bone marrow samples from seven patients with myeloid malignancies and two controls were used for mass cytometric analysis. Various immune cell subsets and leukemic cells were identified using metal-conjugated antibodies against 28 surface antigens. The multidimensional data underwent clustering after dimensionality reduction.

Results

Firstly, all types of acute myeloid leukemia (AML) cells, including AML-M0, M2, M3, M5, M7, and AML with myelodysplasia-related changes, were clearly identified among the various immune cell subsets. In addition to the identification of leukemic cells, a detailed evaluation of immune cell subsets was possible. Mass cytometric analysis was also useful for assessing changes in the immune environment over the course of treatment and for the identification of lineage switches in mixed-phenotype acute leukemia. Finally, we tested the applicability of mass cytometry for the evaluation of measurable residual disease using serial dilution experiments. Although the barcoding system requires optimization, leukemic cells were clearly separated from normal cells across all AML types.

Conclusions

Mass cytometry may be useful for evaluating leukemic cells and the immune environment in pediatric myeloid malignancies.