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Artificial intelligence (AI) trained with a convolutional neural network (CNN) is a recent technological advancement. Previously, several attempts have been made to train AI using medical images for clinical applications. However, whether AI can distinguish microscopic images of mammalian cells has remained debatable. This study assesses the accuracy of image recognition techniques using the CNN to identify microscopic images. We also attempted to distinguish between mouse and human cells and their radioresistant clones. We used phase-contrast microscopic images of radioresistant clones from two cell lines, mouse squamous cell carcinoma NR-S1, and human cervical carcinoma ME-180. We obtained 10,000 images of each of the parental NR-S1 and ME-180 controls as well as radioresistant clones. We trained the CNN called VGG16 using these images and obtained an accuracy of 96%. Features extracted by the trained CNN were plotted using t-distributed stochastic neighbor embedding, and images of each cell line were well clustered. Overall, these findings suggest the utility of image recognition using AI for predicting minute differences among phase-contrast microscopic images of cancer cells and their radioresistant clones.Significance:This study demonstrates rapid and accurate identification of radioresistant tumor cells in culture using artifical intelligence; this should have applications in future preclinical cancer research.

Blood test and serial transplantation of the tumors at the end of the 30 days of each treatment.

Only the mice treated by MQ+SN-38 revealed no apparent signs of tumor regrowth.

Given that cancer stem cells (CSC) play a key role in drug resistance and relapse, targeting CSCs remains promising in cancer therapy. Here we show that RAB5/7, which are involved in the endolysosomal pathway, play key roles in the maintenance of CSC survival via regulation of the mitophagic pathway. Inhibition of RAB5/7 efficiently eliminated colorectal CSCs and disrupted cancer foci. In addition, we identified mefloquine hydrochloride, an antimalarial drug, as a novel RAB5/7 inhibitor and promising colorectal CSC-targeting drug. Endolysosomal RAB5/7 and LAMP1/2 mediated parkin-dependent mitochondrial clearance and modulated mitophagy through lysosomal dynamics. In a patient-derived xenograft (PDX) model of colon cancer, treatment with mefloquine resulted in suppression of mitophagic PINK1/PARKIN and increased mitochondrial disorder and mitochondria-induced apoptosis without apparent side effects. These results suggest that the combination of mefloquine with chemotherapeutic agents in the PDX model potentially disrupts the hierarchy of colorectal cancer cells and identify endolysosomal RAB5/7 and LAMP1/2 as promising therapeutic targets in CSCs.Significance:These findings show that endosomal/lysosomal RAB5 and RAB7, which regulate mitophagy, are essential for the survival of colon cancer stem cells.

Normal epithelial cells exert their competitive advantage over RasV12-transformed cells and eliminate them into the apical lumen via cell competition. However, the internal or external factors that compromise cell competition and provoke carcinogenesis remains unknown. In this study, we examined the effect of sequential accumulation of gene mutations, mimicking multi-sequential carcinogenesis on RasV12-induced cell competition in intestinal epithelial tissues. Consequently, we found that directionality of RasV12-cell extrusion in Wnt-activated epithelia is reversed, and transformed cells are delaminated into the basal lamina via non-cell autonomous MMP21 upregulation. Subsequently, diffusively infiltrating, transformed cells develop into highly invasive carcinomas. Elevated production of MMP21 is elicited partly through NF-κB signaling, blockage of which restores apical elimination of RasV12 cells. We further found that the NF-κB-MMP21 axis is significantly bolstered in early colorectal carcinoma in humans. Collectively, this study shows that cells with high mutational burdens exploit cell competition for their benefit by behaving as unfit cells, endowing them with an invasion advantage.

Summary StatementThe present study is the first report for reproducing human disease by utilizing blastocyst complementation method and would lead to the development of novel therapy for human disease.The application of pluripotent stem cell is expected to contribute to the elucidation of the unknown mechanism of human diseases. However, in vitro induction of cells in several organs, such as the pancreas and liver, remains difficult; therefore, reproduction of those diseases in a model has not been feasible. To reproduce human hereditary pancreatitis (HP), which is most frequently caused by the mutations in thePRSS1gene, we performed the blastocyst complementation (BC) method. In the BC method, mouse embryonic stem (ES) cells harboring CRISPR/CAS9-mediated mutations in thePrss1were injected into the blastocysts of deficientPdx1gene mice, which is a critical transcription factor in the pancreas. The results showed that the blastocysts injected into thePrss1-mutant ES cells induced trypsin activation. This implied that the mouse phenotype mimics that of human HP and that the BC method was useful for the reproduction and study of pancreatic disorders. The present study opens the possibility of investigating uncharacterized human diseases by utilizing the BC method.

Mutations continue to accumulate within the SARS-CoV-2 genome, and the ongoing epidemic has shown no signs of ending. It is critical to predict problematic mutations that may arise in clinical environments and assess their properties in advance to quickly implement countermeasures against future variant infections. In this study, we identified mutations resistant to remdesivir, which is widely administered to SARS-CoV-2-infected patients, and discuss the cause of resistance. First, we simultaneously constructed eight recombinant viruses carrying the mutations detected in in vitro serial passages of SARS-CoV-2 in the presence of remdesivir. Time course analyses of cellular virus infections showed significantly higher infectious titers and infection rates in mutant viruses than wild type virus under treatment with remdesivir. Next, we developed a mathematical model in consideration of the changing dynamic of cells infected with mutant viruses with distinct propagation properties and defined that mutations detected in in vitro passages canceled the antiviral activities of remdesivir without raising virus production capacity. Finally, molecular dynamics simulations of the NSP12 protein of SARS-CoV-2 revealed that the molecular vibration around the RNA-binding site was increased by the introduction of mutations on NSP12. Taken together, we identified multiple mutations that affected the flexibility of the RNA binding site and decreased the antiviral activity of remdesivir. Our new insights will contribute to developing further antiviral measures against SARS-CoV-2 infection.Significance StatementConsidering the emerging Omicron strain, quick characterization of SARS-CoV-2 mutations is important. However, owing to the difficulties in genetically modifying SARS-CoV-2, limited groups have produced multiple mutant viruses. Our cutting-edge reverse genetics technique enabled construction of eight reporter-carrying mutant SARS-CoV-2 in this study. We developed a mathematical model taking into account sequential changes and identified antiviral effects against mutant viruses with differing propagation capacities and lethal effects on cells. In addition to identifying the positions of mutations, we analyzed the structural changes in SARS-CoV-2 NSP12 by computer simulation to understand the mechanism of resistance. This multidisciplinary approach promotes the evaluation of future resistance mutations.

Theoretical methods such as molecular mechanics and molecular dynamics are very useful in understanding the fundamentals of life sciences. We have established a procedure to predict the structure of a complex of p53 with an arbitrary DNA complex, and have made it possible to predict the binding energy of p53 to DNA from the configuration of molecular dynamics simulations of the complex structure. We performed validation studies using FTD, an anti-tumor drug that exerts its pharmacological effect by incorporation into DNA, and confirmed that the binding affinity of the p53-binding BAX sequence to the p53 tetramer was increased by FTD incorporation. This indicates that FTD tends to interact strongly with DNA-binding proteins when incorporated into DNA. On the other hand, the binding affinity of FTD-containing DNA was greatly reduced in p53-binding sequences extracted from FTD-resistant cells compared to that of normal DNA. In other words, it was suggested that randomly substituted thymidine for FTDs in resistant cells may have acquired resistance by entering positions that prevented binding to DNA-binding proteins. We believe that this procedure is a versatile procedure that can take into account the binding energies of not only the p53 protein, but also other DNA-binding proteins and other biomolecules, thus increasing the importance of computational science in the life sciences.

Artificial intelligence (AI) trained with a convolutional neural network (CNN) is a recent technological advancement. Previously, several attempts have been made to train AI using medical images for clinical applications. However, whether AI can distinguish microscopic images of mammalian cells has remained debatable. This study assesses the accuracy of image recognition techniques using the CNN to identify microscopic images. We also attempted to distinguish between mouse and human cells and their radioresistant clones. We used phase-contrast microscopic images of radioresistant clones from two cell lines, mouse squamous cell carcinoma NR-S1, and human cervical carcinoma ME-180. We obtained 10,000 images of each of the parental NR-S1 and ME-180 controls as well as radioresistant clones. We trained the CNN called VGG16 using these images and obtained an accuracy of 96%. Features extracted by the trained CNN were plotted using t-distributed stochastic neighbor embedding, and images of each cell line were well clustered. Overall, these findings suggest the utility of image recognition using AI for predicting minute differences among phase-contrast microscopic images of cancer cells and their radioresistant clones. Significance: This study demonstrates rapid and accurate identification of radioresistant tumor cells in culture using artifical intelligence; this should have applications in future preclinical cancer research.

Cancer stem cells (CSCs) exhibit tumorigenic potential and can generate resistance to chemotherapy and radiotherapy. A labeled ornithine decarboxylase (ODC, a rate-limiting enzyme involved in polyamine [PA] biosynthesis) degradation motif (degron) system allows visualization of a fraction of CSC-like cells in heterogeneous tumor populations. A labeled ODC degradation motif system allowed visualization of a fraction of CSC-like cells in heterogeneous tumor populations. Using this system, analysis of polyamine flux indicated that polyamine metabolism is active in CSCs. The results showed that intracellular polyamines inhibited the activity of histone lysine 4 demethylase enzymes, including lysine-specific demethylase-1 (LSD1). Chromatin immunoprecipitation with Pol II antibody followed by massively parallel DNA sequencing, revealed the global enrichment of Pol II in transcription start sites in CSCs. Increase of polyamines within cells resulted in an enhancement of ID1 gene expression. The results of this study reveal details of metabolic pathways that drive epigenetic control of cancer cell stemness and determine effective therapeutic targets in CSCs.

The significance of mitochondrial metabolism in cancer cells has recently been gaining attention. Among other findings, One-carbon folate metabolism has been reported to be closely associated with cellular characteristics in cancer. To study molecular targets for efficient cancer therapy, we investigated the association between the expressions of genes that code enzymes involved in one-carbon metabolism and survival rate of patients with adenocarcinomas of the colorectum and lung. Patients with high expression of genes that control the metabolic cycle of tetrahydrofolate (THF) in mitochondria, SHMT2, MTHFD2, and ALDH1L2, have a shorter overall survival rate compared with patients with low expression of these genes. Our results revealed that these genes could be novel and more promising anticancer targets than dihydrofolate reductase (DHFR), the current target of drug therapy linked with folate metabolism, suggesting the rationale of drug discovery in cancer medicine.

// Yujiro Nishizawa 1, 2, * , Masamitsu Konno 2, 3, * , Ayumu Asai 2, 3 , Jun Koseki 3 , Koichi Kawamoto 1, 2 , Norikatsu Miyoshi 1 , Hidekazu Takahashi 1 , Naohiro Nishida 1 , Naotsugu Haraguchi 1 , Daisuke Sakai 2 , Toshihiro Kudo 2 , Taishi Hata 1 , Chu Matsuda 1 , Tsunekazu Mizushima 1, 4 , Taroh Satoh 2 , Yuichiro Doki 1 , Masaki Mori 1 and Hideshi Ishii 2, 3 1 Department of Gastroenterological Surgery, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan 2 Department of Frontier Science for Cancer and Chemotherapy, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan 3 Department of Disease Data Science, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan 4 Department of Therapeutics for Inflammatory Bowel Diseases, Graduate School of Medicine, Osaka University, Suita, Osaka, Japan * These authors contributed equally to this work Correspondence to: Hideshi Ishii, email: hishii@gesurg.med.osaka-u.ac.jp Masaki Mori, email: mmori@gesurg.med.osaka-u.ac.jp Keywords: YTHDF1; colorectal cancer; c-MYC; proliferation; chemosensitivity Received: August 31, 2017 Accepted: October 28, 2017 Published: December 21, 2017 ABSTRACT Recent studies that have emerged on the diversity of RNA modification in tumors suggest their eligibility as bona fide targets in diagnosis and drug discovery. N6-methyladenosine (m 6 A) was first reported and is most common in epitranscriptome modification of various RNAs. The YT521-B homology (YTH) domain family are representative m6A-binding proteins, but how the YTH domain family is involved in cancer remains to be clearly understood. Given that clinical sequence data in colorectal cancer indicate that overexpression of YTHDF1 is outstanding among other family members, we studied the role of Ythdf1 and the transcriptional control of YTHDF1. Immunostaining of Ythdf1 showed that its expression was associated with various malignant tumor behaviors, such as depth, lymph node metastasis, and poorer cancer stages. The study of patient survival indicated that patients with high Ythdf1 expression had significantly poorer overall survival. The results indicated that Ythdf1 expression is an independent prognostic factor of patients. The in vitro study showed that the knockdown of YTHDF1 resulted in the suppression of cancer proliferation and sensitization to the exposure of anticancer drugs such as fluorouracil and oxaliplatin. Importantly, the study upstream of the YTHDF1 gene indicated that an oncogenic transcription factor c-Myc was associated with YTHDF1 in both expression and chromatin immunoprecipitation data. Moreover, the knockdown experiments of c-Myc showed the inhibition of YTHDF1, supporting a notion of c-Myc-driven YTHDF1 axis significance. These data suggest that m6A reader Ythdf1 plays a significant role in colorectal cancer progression.

The Golgi-associated PDZ- and coiled-coil motif-containing (GOPC) protein controls the intracellular trafficking of numerous integral membrane proteins. Knockdown of GOPC increases activation of the mitogen-activated protein kinase-extracellular signal-regulated kinase 1/2 pathway and cancer cell progression in colorectal cancer. The present study aimed to clarify the correlation between GOPC expression and prognosis in colorectal cancer. Total RNA was extracted from 153 clinical colorectal cancer specimens and GOPC expression was evaluated using reverse transcription-quantitative polymerase chain reaction. The correlation between GOPC expression and clinicopathological factors was analyzed, along with the association of GOPC expression with overall survival (OS) and with recurrence-free survival (RFS). Lower expression of GOPC was significantly associated with a high frequency of venous invasion (P=0.001) and to poorer OS and RFS based on Kaplan-Meier analysis. In addition, multivariate analyses using a Cox proportional hazards model identified lower expression of GOPC to be an independent prognostic factor for colorectal cancer (hazard ratio=2.800; 95% confidence interval; 1.121–7.648; P=0.027). Lower expression of GOPC revealed a high frequency of venous invasion and associated with poorer prognosis for patients with colorectal cancer.

// Kenta Tsunekuni 1, 2, 3, * , Masamitsu Konno 1, 4, * , Ayumu Asai 1, 2, 4 , Jun Koseki 2 , Takashi Kobunai 3 , Teiji Takechi 3 , Yuichiro Doki 1 , Masaki Mori 1 and Hideshi Ishii 1, 2 1 Department of Gastroenterological Surgery, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan 2 Department of Medical Data Science, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan 3 Translational Research Laboratory, Taiho Pharmaceutical Co, Ltd, Tokushima City, Tokushima, 771-0194, Japan 4 Department of Frontier Science for Cancer and Chemotherapy, Osaka University Graduate School of Medicine, Osaka, 565-0871, Japan * These authors contributed equally to this work Correspondence to: Masaki Mori, email: mmori@gesurg.med.osaka-u.ac.jp Hideshi Ishii, email: hishii@gesurg.med.osaka-u.ac.jp Keywords: colorectal cancer, trifluridine, 5-fluorouracil, let-7d-5p, drug resistance Received: March 28, 2017 Accepted: May 09, 2017 Published: May 23, 2017 ABSTRACT Trifluridine (FTD) is a key component of the novel oral antitumor drug trifluridine/tipiracil, which is approved for the treatment of patients with metastatic colorectal cancer refractory to standard chemotherapies. A microRNA analysis of three colorectal cell lines was conducted to investigate causes of FTD resistance. Drug resistant sublines of DLD-1, HCT-116, and RKO cells were developed by continuous administration of increasing doses of FTD for 5 months. The let-7d-5p gene, which maps to chromosome 9q22.32, was downregulated in the FTD-resistant DLD-1 sublines. DLD-1 cells became more resistant to FTD when let-7d-5p was knocked down and more sensitive when let-7d-5p was overexpressed. The FTD-resistant sublines were not cross-resistant to 5-fluorouracil (5-FU); 5-FU sensitivity was affected only slightly when let-7d-5p was overexpressed or knocked down. These data indicate that let-7d-5p increases sensitivity of FTD but not 5-FU and that let-7d-5p is a potential clinical marker of treatment sensitivity.

Halogen-modified nucleic acid molecules, such as trifluorothymidine (FTD) and 5-fluorouracil, are widely used in medical science and clinical site. These compounds have a very similar nucleobase structure. It is reported that both of these compounds could be incorporated into DNA. The incorporation of FTD produces highly anti-tumor effect. However, it is not known whether to occur a significant effect by the incorporation of 5-fluorouracil. Nobody knows why such a difference will occur. To understand the reason why there is large differences between trifluorothymidine and 5-fluorouracil, we have performed the molecular dynamics simulations and molecular orbital calculations. Although the active interaction energy between Halogen-modified nucleic acids or and complementary adenine was increased, in only FTD incorporated DNA, more strongly dispersion force interactions with an adjacent base were detected in many thermodynamic DNA conformations. As the results, the conformational changes occur even if it is in internal body temperature. Then the break of hydrogen bonding between FTD and complementary adenine base occur more frequently. The double helix structural destabilization of DNA with FTD is resulted from autoagglutination caused by the bonding via halogen orbitals such as halogen bonding and the general van der Waals interactions such as CH–\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\rm{\pi }}$$\end{document}π, lone pair (LP)–\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\rm{\pi }}$$\end{document}π, and \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\rm{\pi }}$$\end{document}π–\documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$${\rm{\pi }}$$\end{document}π interactions. Therefore, it is strongly speculated that such structural changes caused by trifluoromethyl group is important for the anti-tumor effect of FTD alone.

The biological significance of micro (mi)RNAs has traditionally been evaluated according to their RNA expression levels based on the assumption that miRNAs recognize and regulate their targets in an unvarying fashion. Here we show that a fraction of mature miRNAs including miR-17-5p, -21-5p, and -200c-3p and let-7a-5p harbor methyl marks that potentially alter their stability and target recognition. Importantly, methylation of these miRNAs was significantly increased in cancer tissues as compared to paired normal tissues. Furthermore, miR-17-5p methylation level in serum samples distinguished early pancreatic cancer patients from healthy controls with extremely high sensitivity and specificity. These findings provide a basis for diagnostic strategies for early-stage cancer and add a dimension to our understanding of miRNA biology., In cancer it is assumed that microRNAs recognise and regulate their targets uniformly. Here, the authors show that in gastrointestinal cancers methylation of microRNAs may impact their stability, and that levels of microRNA methylation are distinct in pancreatic cancer patients compared to healthy controls with potential diagnostic implications.

Cancer stem cells (CSCs) are involved in metastatic colorectal cancer recurrence, but no effective therapy targeting these cells is currently available. Because trifluridine (FTD)/tipiracil therapy is used for refractory colorectal cancer, we sought to determine whether FTD is effective against CSC-like cells. CD44+CD133+ high-expressing and other populations of human DLD-1 colon cancer cells were separately isolated through fluorescence-activated cell sorting. The sphere-forming activity of each population and the anti-sphere-forming effects of FTD and fluorouracil (5-FU) on CD44+CD133+ cells were then measured. CD44+CD133+ DLD-1 cells formed substantially more spheres than other cells. Moreover, treating CD44+CD133+ DLD-1 cells with subtoxic concentrations of FTD (1 µM) inhibited sphere formation, and this was superior to the effect of subtoxic concentrations (1 µM) of 5-FU. The associated inhibition rates for FTD and 5-FU were 58.2% and 26.1%, respectively. Further, CD44+CD133+ DLD-1 cells expressed higher levels of thymidine kinase 1, which is responsible for FTD phosphorylation, than DLD-1 cells, and FTD was incorporated into the DNA of CD44+CD133+ DLD-1 cells. Thus, our data show that FTD treatment is effective against CSC-like cells and might be applied as CSC-targeting chemotherapy for tumor subtypes with high CD44 and CD133 expression.

Members of the ADAMTS family contain propeptide, metalloproteinase and disintegrin domains and serve key roles for cancer cell proliferation, progression and metastasis. Although overexpression of ADAMTS5 has been reported in glioblastoma, and head and neck cancer, little has been demonstrated in colorectal cancer types. The present study aimed to clarify the significance of ADAMTS5 for clinicopathological factors and prognosis in colorectal cancer. The mRNA expression of ADAMTS5 was measured in 143 colorectal cancer specimens. ADAMTS5 expression was increased as the pathological stage increased. The expression of ADAMTS5 in stage III-IV colorectal cancer was significantly greater compared with that of stage 0-II colorectal cancer (P=0.0003). The median expression of ADAMTS5 was used to divide the ADAMTS5 higher expressing group and the ADAMTS5 lower expressing group to assess the correlation of ADAMTS5 expression with clinicopathological factors and prognosis. The proportions of lymphatic invasion and lymph node metastasis were significantly greater in the ADAMTS5 higher expressing group (P=0.0214 and P=0.0289 respectively). Overall survival and disease-free survival were assessed by the Kaplan-Meier curve with calculation of significance by the log-rank test; however, no significant difference was observed between the ADAMTS5 higher expressing group and the ADAMTS5 lower expressing group (P=0.7490 and P=0.9455, respectively). The present study confirmed high expression of ADAMTS5 as a potent marker for lymphatic invasion and lymphnode metastasis in colorectal cancer. To clarify the function of ADAMTS5 in colorectal cancer, further molecular investigations are required.

Antitumor drug therapy plays a very important role in cancer treatment. However, resistance to chemotherapy is a serious issue. Many studies have been conducted to understand and verify the cause of chemoresistance from multiple points of view such as oncogenes, tumor suppressor genes, DNA mutations and repairs, autophagy, cancer stemness, and mitochondrial metabolism and alteration. Nowadays, not only medical data from hospitals but also public big data exist on internet websites. Consequently, the importance of computational science has vastly increased in biological and medical sciences. Using statistical or mathematical analyses of these medical data with conventional experiments, many researchers have recently shown that there is a strong relationship between the biological metabolism and chemoresistance for cancer therapy. For example, folate metabolism that mediates one-carbon metabolism and polyamine metabolism have garnered attention regarding their association with cancer. It has been suggested that these metabolisms may be involved in causing resistance to chemotherapy.

Mitochondrial pyruvate carrier (MPC) is known to cause different expressions in normal and cancer cells. We observed a change in phenotype with the suppression of MPC expression. We knocked down MPC1 and/or MPC2 using siRNA or shRNA. We observed its cell morphology and accompanying molecular marker. Furthermore, the radioresistance of the MPC knockdown cell line was examined using a colony formation assay. MPC1-suppressed cells changed their morphology to a spindle shape. Epithelial-mesenchymal transition (EMT) was suspected, and examination of the EMT marker by PCR showed a decrease in E-cadherin and an increase in fibronectin. Focusing on glutamine metabolism as the mechanism of this phenomenon, we knocked down the glutamine-metabolizing enzyme glutaminase (GLS). EMT was also observed in GLS-suppressed cells. Furthermore, when MPC1-suppressed cells were cultured in a glutamine-deficient medium, changes in EMT markers were suppressed. In addition, MPC1-suppressed cells also increased with a significant difference in radioresistance. Decreased MPC1 expression favorably affects EMT and radioresistance of cancer.

Identifying positions at which anticancer drug molecules incorporate into DNA is essential to define mechanisms underlying their activity, but current methodologies cannot yet achieve this. The thymidine fluorine substitution product trifluridine (FTD) is a DNA-damaging anticancer agent thought to incorporate into thymine positions in DNA. This mechanism, however, has not been directly confirmed. Here, we report a means to detect FTD in a single-stranded oligonucleotide using a method to distinguish single molecules by differences in electrical conductance. Entire sequences of 21-base single-stranded DNAs with and without incorporated drug were determined based on single-molecule conductances of the drug and four deoxynucleosides, the first direct observation of its kind. This methodology may foster rapid development of more effective anticancer drugs.

Given that cancer stem cells (CSC) play a key role in drug resistance and relapse, targeting CSCs remains promising in cancer therapy. Here we show that RAB5/7, which are involved in the endolysosomal pathway, play key roles in the maintenance of CSC survival via regulation of the mitophagic pathway. Inhibition of RAB5/7 efficiently eliminated colorectal CSCs and disrupted cancer foci. In addition, we identified mefloquine hydrochloride, an antimalarial drug, as a novel RAB5/7 inhibitor and promising colorectal CSC-targeting drug. Endolysosomal RAB5/7 and LAMP1/2 mediated parkin-dependent mitochondrial clearance and modulated mitophagy through lysosomal dynamics. In a patient-derived xenograft (PDX) model of colon cancer, treatment with mefloquine resulted in suppression of mitophagic PINK1/PARKIN and increased mitochondrial disorder and mitochondria-induced apoptosis without apparent side effects. These results suggest that the combination of mefloquine with chemotherapeutic agents in the PDX model potentially disrupts the hierarchy of colorectal cancer cells and identify endolysosomal RAB5/7 and LAMP1/2 as promising therapeutic targets in CSCs. Significance: These findings show that endosomal/lysosomal RAB5 and RAB7, which regulate mitophagy, are essential for the survival of colon cancer stem cells.

There are several obstacles to overcome prior to achieving cellular reprogramming of pancreatic β cells in vitro and in vivo. The present study demonstrated that the transfer of epigenetic phenotypes was achieved in the cell-free conditioned medium (CM) of pancreatic insulinoma MIN6 cell cultures. The comparison of a subpopulation of MIN6, m14 and m9 cells indicated that MIN6-m14 cells were more prone to cellular reprogramming. Epigenetic profiling revealed that the transcription factor pancreas/duodenum homeobox protein 1 (Pdx1) was differentially associated among the clones. The culture of differentiated adipocytes in the CM of MIN6-m14 cells resulted in the induction of insulin mRNA expression, and was accompanied by epigenetic events of Pdx1 binding. The epigenetic profiling indicated that Pdx1 is preferentially associated with a previously uncharacterized region of the endoplasmic reticulum (ER) disulfide oxidase, ER oxidoreductin 1 gene. Therefore, the results of the present study indicated that the CM of MIN6 cells was able to induce a pancreatic β cell-like phenotype in differentiated adipocytes. These data provide additional support for the utility of cell-free CM for cellular reprogramming.

Pancreatic adenocarcinoma is thought to develop from histologically identifiable intraductal lesions known as pancreatic intraepithelial neoplasias (PanINs), which exhibit similar morphological and genetic features to pancreatic ductal adenocarcinoma (PDAC). Therefore, a better understanding of the biological features underlying the progression of PanIN is essential to development more effective therapeutic interventions for PDAC. In recent years, numerous studies have reported that MET proto-oncogene receptor tyrosine kinase (c-MET) is a potential marker of pancreatic cancer stem cells (CSCs). CSCs have been revealed to initiate and propagate tumors in vitro and in vivo, and are associated with a chemoresistant phenotype. However, in vivo models using a xenograft approach are limited. In the present study, the morphological phenotype, molecular alteration and biological behavior of neoplasia in Pdx-1Cre/+, KrasLSL-G12D/+ and Metflox/flox and wild-type mice was analyzed. The results demonstrated that while oncogenic KrasLSL-G12D/+ increased PanIN initiation and significantly decreased survival rate compared with wild-type mice, no additive effect of c-Met receptor signaling on PanIN progression or prognosis was observed. Following gemcitabine administration, c-Met inhibition in Kras LSL-G12D/+ mice significantly decreased the total surface area of PanIN lesions and the number of anti-proliferation marker protein Ki-67 positive cells occupying PanIN lesions compared with Met+/+ mice. In conclusion, complete inhibition of the c-Met signaling pathway with chemotherapy may be useful for the treatment of pancreatic cancer.

Hepcidin and ferroportin, which are known as key iron regulators, may be used in future treatments of pancreatic ductal adenocarcinoma. Iron is essential for life support; it helps oxygen molecules bind to hemoglobin and acts as an important catalytic enzyme center. However, iron overload is a risk factor for cancer, possibly through the generation of reactive oxygen species (ROS). Hepcidin, which is a peptide hormone mainly generated by the liver, inhibits iron absorption via enterocytes and iron release from macrophages. Notably, hepcidin regulates iron homeostasis in the body by regulating the iron transporter ferroportin. In the present study, it was assumed that high hepcidin expression and low ferroportin expression result in malignancy. Therefore, it was examined whether hepcidin and ferroportin expression levels were correlated with the prognosis of pancreatic cancer in patients. Results revealed that high hepcidin expression levels and low ferroportin expression levels in pancreatic cancer tissue were significantly associated with poor prognosis in the analyses of overall survival (P=0.0140 and 0.0478, respectively). Additionally, there was no significant difference in disease-free survival in the hepcidin- and ferroportin-staining groups. Hepcidin expression correlated with the pathological stage and vascular invasion (P=0.0493 and 0.0400, respectively), and ferroportin expression was correlated with age (P=0.0372). Multivariate analysis of overall survival in the hepcidin-staining group revealed that pathological N factor (pN), adjuvant chemotherapy, and hepcidin expression were independent prognostic factors (P=0.0450, 0.0002, and 0.0049, respectively). Similarly, multivariate analysis of overall survival in the ferroportin-staining group revealed that vascular invasion, and ferroportin expression were independent prognostic factors (P=0.0028, P

Fetal cells in the developmental stages function with a distinct mechanism in comparison to adult tissues, which may be a useful source for regenerative medicine in postnatal medicine; however, the precise molecular mechanism remains to be elucidated fully. The present study investigated murine fetal hepatocytes, which were cultured in vitro, and the supernatants were used for the culture with murine adipose tissue-derived cells. Notably, the results indicated that fetal hepatocyte-derived culture medium elicits the induction of differentiation of adipose tissue-derived cells to bile duct cell lineages, but not to hepatocyte lineages in mice. This indicates that fetal cells possess the multi potentials, which are already absent in adults, and may be useful for regenerative medicine in future.

The natural product argadin is a cyclopentapeptide chitinase inhibitor that binds to chitinase B (ChiB) from the pathogenic bacteria Serratia marcescens. N(ω)-Acetyl-L-arginine and L-aminoadipic acid of argadin form intramolecular ionic hydrogen bonds in the aromatic hydrophobic pocket of ChiB. We performed ab initio molecular orbital and density functional theory calculations to elucidate the role of this intramolecular hydrogen bonding on intermolecular interactions between argadin and ChiB. We found that argadin accrues large stabilization energies from the van der Waals dispersion interactions, such as CH-π, π-π, and π-lone pair interactions, in the aromatic hydrophobic pocket of ChiB, although intramolecular hydrogen bonding within argadin might result in loss of entropy. The intramolecular ionic hydrogen bonding formation canceled local molecular charges and provided good van der Waals interactions with surrounding aromatic residues.

Pancreatic cancer has a poor prognosis because of its high invasiveness and recurrence, and these properties closely link to the phenomenon of epithelial-mesenchymal transition (EMT). Recently, it has been reported that Sox4 is indispensable for EMT in vitro and in vivo and regulates various master regulators of EMT including Zeb, Twist and Snail. Moreover, Sox4 induces the transcription of Ezh2 which is the histone methyltransferase, and reprograms the cancer epigenome to promote EMT and metastasis. Therefore, the present study evaluated the importance of Sox4, Ezh2 and miR-335, which regulate Sox4 expression epigenetically, in clinical samples with pancreatic cancer. This retrospective analysis included data from 36 consecutive patients who underwent complete surgical resection for pancreatic cancer and did not undergo any preoperative therapies. We assessed the clinical significance of Sox4/Ezh2 axis and miR-335 expression, using immunohistochemistry and qRT-PCR with laser captured microdissection (LCM). The Sox4 positive patients had significantly worse prognosis as for disease-free survival (DFS) (P=0.0154) and the Ezh2-positive patients had significantly worse prognosis as for overall survival (OS) (P=0.0347). The miR-335 expression was inversely correlated with Sox4 expression in the identical clinical specimens, but it was not related to the prognosis. Sox4/Ezh2 axis was closely associated with the prognosis in pancreatic cancer patients.

Cancer stem cells (CSCs) are a small population of cells in cancer with stem-like properties such as cell proliferation, multiple differentiation and tumor initiation capacities. CSCs are therapy-resistant and cause cancer metastasis and recurrence. One key issue in cancer therapy is how to target and eliminate CSCs, in order to cure cancer completely without relapse and metastasis. To target CSCs, many cell surface markers, DNAs and microRNAs are considered as CSC markers. To date, the majority of the reported markers are not very specific to CSCs and are also present in non-CSCs. However, the combination of several markers is quite valuable for identifying and targeting CSCs, although more specific identification methods are needed. While CSCs are considered as critical therapeutic targets, useful treatment methods remain to be established. Epigenetic gene regulators, microRNAs, are associated with tumor initiation and progression. MicroRNAs have been recently considered as promising therapeutic targets, which can alter the therapeutic resistance of CSCs through epigenetic modification. Moreover, carbon ion beam radiotherapy is a promising treatment for CSCs. Evidence indicates that the carbon ion beam is more effective against CSCs than the conventional X-ray beam. Combination therapies of radiosensitizing microRNAs and carbon ion beam radiotherapy may be a promising cancer strategy. This review focuses on the identification and treatment resistance of CSCs and the potential of microRNAs as new radiosensitizers and carbon ion beam radiotherapy as a promising therapeutic strategy against CSCs.

Previous reports have indicated that reprogramming technologies may be useful for altering the malignant phenotype of cancer cells. Although somatic stem cells in normal tissues are more sensitive to reprogramming induction than differentiated cells, it remains to be elucidated whether any specific subpopulations are sensitive to reprogramming in heterogeneous tumor tissues. Here we examined the susceptibility of pancreatic cancer stem cells (CSC) and non-CSC to reprogramming. To characterize CSC populations, we focused on c-Met signaling, which has been identified as a marker of CSC in mouse experiments in vivo. Cells that expressed high levels of c-Met showed higher CSC properties, such as tumor-initiating capacity, and resistance to gemcitabine. Real-time reverse transcription-polymerase chain reaction in cells expressing high levels of c-Met revealed endogenous expression of reprogramming factors, such as OCT3/4, SOX2, KLF4 and cMYC. Introduction of these four factors resulted in higher alkaline phosphatase staining in cells with high c-Met expression than in controls. Therefore, the study results demonstrate that cellular reprogramming may be useful for extensive epigenetic modification of malignant features of pancreatic CSC.

Background: SIRT4, which is localised in the mitochondria, is one of the least characterised members of the sirtuin family of nicotinamide adenine dinucleotide-dependent enzymes that play key roles in multiple cellular processes such as metabolism, stress response and longevity. There are only a few studies that have characterised its function and assessed its clinical significance in human cancers. Methods: We established colorectal cancer cell lines (SW480, HCT116, and HT29) overexpressing SIRT4 and investigated their effects on proliferation, migration and invasion, as well as E-cadherin expression, that negatively regulates tumour invasion and metastases. The associations between SIRT4 expression in colorectal cancer specimens and clinicopathological features including prognosis were assessed by immunohistochemistry. Results: SIRT4 upregulated E-cadherin expression and suppressed proliferation, migration and invasion through inhibition of glutamine metabolism in colorectal cancer cells. Moreover, SIRT4 expression in colorectal cancer decreased with the progression of invasion and metastasis, and a low expression level of SIRT4 was correlated with a worse prognosis. Conclusions: SIRT4 has a tumour-suppressive function and may serve as a novel therapeutic target in colorectal cancer.