Red, blue, and green: A red NiIIAuI complex with a low‐spin square‐planar NiN2S2 configuration can be converted into a green high‐spin octahedral NiO3S3 complex by lowering the pH (see scheme; pH change: red arrows). Increasing the Ni/Au ratio (Ni/Au change: blue arrows) gives a light blue octahedral NiN2O2S2 complex; increasing the pH or decreasing the Ni/Au ratio gives a blue octahedral NiN3S3 configuration.

No abstract

Cancer stem cells (CSC) are a subpopulation of tumor cells with properties of high tumorigenicity and drug resistance, which lead to recurrence and poor prognosis. Although a better understanding of CSC is essential for developing cancer therapies, scarcity of the CSC population has hindered such analyses. The aim of the present study was to elucidate whether the E‐cadherin‐Fc chimera protein (E‐cad‐Fc) enhances cancer stem‐like properties because studies show that soluble E‐cadherin stimulates human epithelial growth factor receptor (EGFR) and downstream signaling pathways that are reported to play a crucial role in CSC. For this purpose, we used ornithine decarboxylase (ODC)‐degron–transduced (Degron(+)) KM12SM cells as a CSC model that retains relatively low CSC properties. Compared to cultures without E‐cad‐Fc treatment, we found that E‐cad‐Fc treatment further suppressed proteasome activity and largely enhanced cancer stem‐like properties of ODC‐degron–transduced KM12SM cells. These results include increased expression of stem cell markers Lgr5, Bmi‐1, SOX9, CD44, and CD44v9, aldehyde dehydrogenase (ALDH), and enhancement of robust spheroid formation, and chemoresistance to 5‐fluorouracil (5‐FU) and oxaliplatin (L‐OHP). These effects could be attributed to activation of the EGFR pathway as identified by extensive phosphorylation of EGFR, ERK, PI3K, AKT, and mTOR. In SW480 cells, E‐cad‐Fc matrix induced some CSC markers such as CD44v9 and ALDH. We also found that E‐cad‐Fc matrix showed high efficiency of inducing mesenchymal changes in colon cancer cells. Our data suggest that the E‐cad‐Fc matrix may enhance CSC properties such as enhancement of chemoresistance and sphere formation.

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Treatment of [Au(d-pen-S)2]3− (d-H2pen = d-penicillamine) with [PdCl4]2− in a 1:1 ratio gave a S-bridged PdII2AuI2 tetranuclear complex, in which two square-planar [Pd(d-pen-N,S)2]2− units are linked by two linear AuI ions. This tetranuclear complex was found to form two geometrical isomers that are discriminated by the cis–trans isomerism of [Pd(d-pen-N,S)2]2− units.