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Aim: To investigate the expression of cancer stem cell-like phenotypes in invasive pancreatic ductal adenocarcinoma, we analysed the correlation between the expression status of stemness markers and minichromosome maintenance 2 (MCM2), and clinicopathological characteristics; we also evaluated the prognostic significance of cancer stem cell-like features. Methods and results: We performed immunohistochemical staining in 44 cases of invasive pancreatic ductal adenocarcinoma. Patients were classified into high-expression and low-expression groups on the basis of the expression level of CD133, CD44, ALDH1, EpCAM, and MCM2. Seventeen of the 44 cases (39%) demonstrated high expression levels of CD133, whereas 12 of the 44 cases (27%) demonstrated high expression levels of CD44; 36 of the 44 cases (81%) demonstrated high expression levels of ALDH1, and 21 of the 44 cases (47%) demonstrated high expression levels of EpCAM. MCM2 was expressed in the nuclei of cancer cells with a positive cell ratio that ranged from 10% to 70%. Frequent positive stemness markers and/or a low expression of MCM2 was significantly correlated with worse overall survival (P=0.030). We defined frequent positive stemness markers (number of highly expressed markers>3) and/or a low expression of MCM2 phenotypes as the representative pattern of a cancer stem cell-like phenotype. The cancer stem cell-like phenotype was identified as an independent factor of overall survival by univariate (P=0.03) and multivariate analysis (hazard ratio, 2.763%; 95% confidence interval, 1.121-6.813; P=0.0273). Conclusion: The cancer stem cell-like phenotype could be involved in therapeutic resistance, resulting in worse overall survival. The cancer stem cell-like phenotype can be an indicator of recurrence in cases of invasive pancreatic ductal adenocarcinoma.

A persistent photoinduced metal-to-insulator transition has been confirmed in a manganite thin film, ${\mathrm{Pr}}_{0.55}({\mathrm{Ca}}_{0.75}{\mathrm{Sr}}_{0.25}{)}_{0.45}{\mathrm{MnO}}_{3}$, near a multicritical point by monitoring with transport measurements and x-ray photoemission spectroscopy. Together with the previously reported reverse effect, the photoinduced insulator-to-metal transition, it is found that the relative stability of the metallic and insulating phases interchanges around 80 K in the middle of a very wide hysteresis loop, which is a manifestation of the large potential barrier due to the long-range elastic energy. It is shown that photons are much more effective in overcoming the barrier via the electronically excited intermediate states than via the heat mode.