In Japan, S-1 is used as adjuvant chemotherapy for pancreatic cancer. Neutropenia during S-1 chemotherapy is reported to be an independent predictor of prolonged survival in patients with advanced gastric cancer. However, this is unclear in pancreatic cancer. This study aimed to examine the effect of severe neutropenia caused by S-1 adjuvant chemotherapy on pancreatic cancer prognosis: overall survival (OS) and recurrence-free survival (RFS), and the potential effect of the duration from surgery to S-1 administration on OS and RFS. This single-center, retrospective, observational study included patients who newly received S-1 adjuvant chemotherapy after curative resection of pancreatic cancer at the Japanese Red Cross Kyoto Daini Hospital between January 1, 2016, and September 30, 2020. Of the 43 patients, 9 had grade 3 or higher neutropenia (G3 group) and had a significantly longer median OS than the other 34 (non-G3 group) did. The median RFS of the G3 group was longer than that of the non-G3 group. The median time from surgery to S-1 administration was significantly shorter in the G3 group than in the non-G3 group. Cox proportional hazards regression analysis revealed that duration from surgery to S-1 administration <51 d (hazard ratio: 0.375, 95% confidence interval: 0.154–0.914, p = 0.031) and occurrence of grade 3 neutropenia (hazard ratio: 0.198, 95% confidence interval: 0.046–0.860, p = 0.031) were significantly associated with prolonged OS. In conclusion, initiating S-1 adjuvant chemotherapy early after surgery and the occurrence of grade 3 neutropenia may improve pancreatic cancer prognosis.

Metallothionein (MT) is a small-molecule protein that functions in essential trace element homeostasis. Among MT isoforms, MT3 is involved in neuronal activity, and its expression is reported to be decreased in patients with neurodegenerative conditions such as Alzheimer’s disease; however, only a few effective drugs have been reported to induce MT3 expression. In this study, we evaluated existing drugs for the induction of MT3 expression in the neuronal cell line of ReNcell CX cells. Using recombinant proteins of MT isoforms with the 3× Flag tag, we performed Western blotting (WB) with the primary antibodies against MT3 or Flag tag, and this method of WB for MT3 was confirmed specifically to detect the MT3 protein. We treated ReNcell CX cells with several HIF-PH inhibitors and evaluated MT3 expression via real-time RT-PCR. We found that FG4592 significantly enhanced MT3 expression at both RNA and protein levels. FG4592 treatment increased the amount of hypoxia-inducible factor 1 alpha (HIF1α) binding to the MT3 promoter. These findings indicate that FG4592 induces MT3 expression via increased HIF1α. In conclusion, we found FG4592 to be an endogenous MT3 inducer in the cells of the nervous system in this study. The findings of this study are expected to lead to the development of new MT3-inducing drugs for neurodegenerative diseases based on FG4592.

Fluorescence imaging analysis was performed in cardiomyocytes from the sinus node, the orthotopic pacemaker, and the pulmonary vein, a potential ectopic pacemaker that may cause atrial fibrillation, focusing on the role of the Na⁺/Ca²⁺ exchanger (NCX). Isolated cardiomyocytes from the guinea pig pulmonary vein and sinus node showing automaticity were loaded with fluorescence probes for analysis. Inhibition of NCX by SEA0400 decreased the Ca²⁺ transient frequency in the pulmonary vein cardiomyocytes but not in the sinus node. The basal intracellular Ca²⁺ concentration, as well as the number of Ca²⁺ sparks in the subsarcolemmal region, was higher in the pulmonary vein cardiomyocytes than in the sinus node. By contrast, the intracellular Na⁺ concentration was not different between the pulmonary vein and sinus node cardiomyocytes. The equilibrium potential for NCX (E_NCX) was estimated to be less negative in the pulmonary vein cardiomyocytes than in the sinus node. In conclusion, the forward mode NCX is involved in spontaneous activity in the pulmonary vein cardiomyocytes but not in the sinus node; this is probably because the Ca²⁺ supply and the driving force for the forward mode NCX are both larger in the pulmonary vein cardiomyocytes than in the sinus node.

Carboxylesterase (CES) plays an important role in the metabolism of ester-containing drugs such as prodrugs and is highly expressed in the human intestine and liver. The ideal prodrug is barely hydrolyzed by human intestinal CES (CES2A1) but is extensively converted to an active drug by human hepatic CES (CES1A). It is, therefore, important to evaluate CES2A1-mediated hydrolysis during intestinal absorption. Unfortunately, Caco-2 cells, the most common enterocyte model for drug permeability, are not suitable for permeability studies of prodrugs due to their high and extremely low expression of CES1A and CES2A1, respectively. Previously, we have prepared CES2/Caco-2^CES1KD cells with reduced human CES1A and highly expressed CES2A1. In the present study, the metabolic and transport properties of CES2/Caco-2^CES1KD cells were characterized. The expression of transporters and metabolizing enzymes other than CESs was similar in CES2/Caco-2^CES1KD and Caco-2 cells. However, the expression of CES2A1 in CES2/Caco-2^CES1KD was about 7–10 fold higher than that of CES1A in Caco-2 cells and comparable to levels found in the human intestine. Hydrolysis during transport across cell monolayers was analyzed using ethyl and butyl esters of p-aminobenzoic acid (PABA). Ethyl PABA, a better substrate for CES1A than CES2A1, was similarly hydrolyzed in Caco-2 and CES2/Caco-2^CES1KD cell monolayers due to the high expression of CES2A1 in CES2/Caco-2^CES1KD cells. Butyl PABA, a good substrate for CES2A1, was substantially hydrolyzed in CES2/Caco-2^CES1KD cell monolayers, in contrast to negligible hydrolysis in Caco-2 cell monolayers. N-Acetylation of PABA derived from PABA esters showed similar activity in Caco-2 and CES2/Caco-2^CES1KD cell monolayers.

The non-canonical phosphorylation of the receptor tyrosine kinase ephrin type-A receptor 2 (EphA2) at Ser-897 plays crucial roles in tumor progression in a tyrosine kinase-independent manner. This phosphorylation is catalyzed by p90 ribosomal S6 kinase (RSK), a kinase downstream of extracellular signal-regulated kinase (ERK). We recently reported that stress-responsive kinase mitogen-activated protein kinase (MAPK)-activated protein kinase 2 (MK2), instead of ERK, regulates RSK under cellular stress conditions; however, the function of MK2 in ERK-activated cells is still unknown. We herein clarified that MK2 regulates the RSK-EphA2 axis in ERK-activated echinoderm microtubule-associated protein-like 4-anaplastic lymphoma kinase (EML4-ALK) lung cancer cells. In addition, an MK2 inhibitor blocked enhancements in cell motility induced by the constitutively activated RSK-EphA2 axis. The present results reveal the importance of MK2 in the ERK-activated non-canonical activation of EphA2.