Mitochondrial inhibitor sodium azide inhibits the reorganization of mitochondria-rich cytoplasm and the establishment of the anteroposterior axis in ascidian embryo.

In ascidian eggs, cytoplasmic and cortical reorganization, previously called ooplasmic segregation, occurs in two phases during the first cell cycle. In the second phase of reorganization, the mitochondria-rich cytoplasm (myoplasm) moves to the future posterior side, concurrent with sperm aster migration along the egg cortex. Although this reorganization is the critical step for establishing the anteroposterior axis, its molecular mechanism is not fully understood. In this study, we showed that low concentrations of the mitochondrial inhibitor sodium azide (NaN3 ), which showed the low toxicity in sperm, inhibited the second phase of reorganization without the microtubule depolymerization. In the NaN3 -treated embryo, the sperm aster was not attracted to the cortex and altered its migration pathway; therefore, the myoplasm remained at the vegetal pole. Consequently, the anteroposterior axis was not established. Another mitochondrial inhibitor, oligomycin, did not affect these processes. These results suggest that NaN3 inhibits unknown molecules that are important for the second phase of reorganization. Identifying the target molecule of NaN3 will lead to a molecular understanding of cytoplasmic and cortical reorganization.

Simultaneous expression of cancer stem cell-like properties and cancer-associated fibroblast-like properties in a primary culture of breast cancer cells.

The importance of cancer-associated fibroblasts (CAFs) in cancer biology has been recently highlighted owing to their critical roles in cancer growth, progression, metastasis, and therapeutic resistance. We have previously established a primary culture of breast cancer cells, which showed epithelial-mesenchymal transition and cancer stem cell-like properties. In this study, we found that the primary culture also showed CAF-like properties. For example, hypoxia inducible factor 1α (HIF1A) and its downstream genes, nuclear factor-kappa B2 (NF-κB2) and BCL2/adenovirus E1B 19 kd-interacting protein 3 (BNIP3), and many enzymes involved in glycolysis, such as GAPDH, LDH, PGAM1, and PKM2, were highly overexpressed in the primary culture. Moreover, media conditioned with the primary culture cells enhanced the growth of breast cancer cells. Similar to previous CAF studies, this enhancement suggested to be occurred through fibroblast growth factor signaling. This MCKH primary culture cell, which showed simultaneous expression of tumorigenic and CAF properties, offers a unique experimental system for studying the biology of CAFs.