Epithelial metaplasia occurs when one predominant cell type in a tissue is replaced by another, and is frequently associated with an increased risk of subsequent neoplasia. In both mouse and human pancreas, acinar-to-ductal metaplasia has been implicated in the generation of cancer precursors. We show that pancreatic epithelial explants undergo spontaneous acinar-to-ductal metaplasia in response to EGFR signaling, and that this change in epithelial character is associated with the appearance of nestin-positive transitional cells. Lineage tracing involving Cre/lox-mediated genetic cell labeling reveals that acinar-to-ductal metaplasia represents a true transdifferentiation event, mediated by initial dedifferentiation of mature exocrine cells to generate a population of nestin-positive precursors, similar to those observed during early pancreatic development. These results demonstrate that a latent precursor potential resides within mature exocrine cells, and that this potential is regulated by EGF receptor signaling. In addition, these observations provide a novel example of rigorously documented transdifferentiation within mature mammalian epithelium, and suggest that plasticity of mature cell types may play a role in the generation of neoplastic precursors.

TP53, encoding p53, is one of the most famous tumor suppressor genes. The majority of human cancers demonstrate the inactivation of the p53 pathway. Mutant p53 not only, no longer, functions as a tumor suppressor but can also exert tumor-promoting effects. The basic function of p53 is to respond to cellular stress. We herein review the recent advances in p53 research and focus on apoptosis, cell cycle arrest, and senescence in response to stress. We also review the clinical applications of p53-based therapy for human cancer.

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This synopsis outlines the Japanese guideline Version 2.0 for the data acquisition protocol of oncology FDG-PET/CT scans that was created by a joint task force of the Japanese Society of Nuclear Medicine Technology, the Japanese Society of Nuclear Medicine and the Japanese Council of PET Imaging, and was published in Kakuigaku-Gijutsu 2013; 33:377–420 in Japanese. The guideline aims at standardizing the PET image quality among PET centers and different PET camera models by providing criteria for the IEC body phantom image quality as well as for the patient PET image quality based on the noise equivalent count (NEC), NEC density and liver signal-to-noise ratio, so that the appropriate scanning parameters can be determined for each PET camera. This Version 2.0 covers issues that were not focused on in Version 1.0, including the accuracy of the standardized uptake value (SUV), effect of body size together with adjustment of scanning duration, and time-of-flight (TOF) reconstruction technique. Version 2.0 also presents data acquired with new PET camera models that were not tested in Version 1.0. Reference values for physical indicators of phantom image quality have been updated as well.