Wnt activation disturbs cell competition and causes diffuse invasion of transformed cells through NF-κB-MMP21 pathway

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 remain elusive. In this study, we examine the effect of sequential accumulation of gene mutations, mimicking multi-sequential carcinogenesis on RasV12-induced cell competition in intestinal epithelial tissues. Consequently, we find that the 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. The elevated production of MMP21 is elicited partly through NF-κB signaling, blockage of which restores apical elimination of RasV12 cells. We further demonstrate 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.

Cancer-specific tissue-resident memory T-cells express ZNF683 in colorectal cancer

BACKGROUND

Tissue-resident memory T (Trm) cells are associated with cytotoxicity not only in viral infection and autoimmune disease pathologies but also in many cancers. Tumour-infiltrating CD103⁺ Trm cells predominantly comprise CD8 T cells that express cytotoxic activation and immune checkpoint molecules called exhausted markers. This study aimed to investigate the role of Trm in colorectal cancer (CRC) and characterise the cancer-specific Trm.

METHODS

Immunochemical staining with anti-CD8 and anti-CD103 antibodies for resected CRC tissues was used to identify the tumour-infiltrating Trm cells. The Kaplan-Meier estimator was used to evaluate the prognostic significance. Cells immune to CRC were targeted for single-cell RNA-seq analysis to characterise cancer-specific Trm cells in CRC.

RESULTS

The number of CD103⁺/CD8⁺ tumour-infiltrating lymphocytes (TILs) was a favourable prognostic and predictive factor of the overall survival and recurrence-free survival in patients with CRC. Single-cell RNA-seq analysis of 17,257 CRC-infiltrating immune cells revealed a more increased zinc finger protein 683 (ZNF683) expression in cancer Trm cells than in noncancer Trm cells and in high-infiltrating Trm cells than low-infiltrating Trm in cancer, with an upregulated T-cell receptor (TCR)- and interferon-γ (IFN-γ) signalling-related gene expression in ZNF683⁺ Trm cells.

CONCLUSIONS

The number of CD103⁺/CD8⁺ TILs is a prognostic predictive factor in CRC. In addition, we identified the ZNF683 expression as one of the candidate markers of cancer-specific Trm cells. IFN-γ and TCR signalling and ZNF683 expression are involved in Trm cell activation in tumours and are promising targets for cancer immunity regulation.

Clinicopathological significance of MYL9 expression in pancreatic ductal adenocarcinoma

BACKGROUND

Pancreatic ductal adenocarcinoma is one of the most aggressive malignancies, and often involves invasion and distant metastasis from the early tumor stages. Myosin II reportedly plays a key role in regulating tumor progression and metastasis.

AIMS

We examined whether myosin regulatory light polypeptide 9 (MYL9) regulates cancer cell proliferation.

METHODS AND RESULTS

To investigate the expression pattern and clinical significance of MYL9 in pancreatic ductal adenocarcinoma, we performed immunohistochemical analysis of samples collected from 101 patients with pancreatic ductal adenocarcinoma. The expression of MYL9 was investigated to evaluate its functional role and contribution to proliferation and apoptosis in pancreatic ductal adenocarcinoma cells in vitro. The results showed that MYL9 was predominantly expressed in the cytoplasm and membrane of pancreatic ductal adenocarcinoma cells. Multivariate analysis indicated that MYL9 acted as an independent prognostic factor for overall survival and distant metastasis-free survival. MYL9 expression was strongly associated with malignancy in in vitro analyses, including proliferation and anti-apoptotic activities.

CONCLUSIONS

Our findings suggest that MYL9 is an independent prognostic factor of pancreatic ductal adenocarcinoma. MYL9 is a crucial biomarker and potential therapeutic target for pancreatic ductal adenocarcinoma.

N(6)-methyladenosine methylation-regulated polo-like kinase 1 cell cycle homeostasis as a potential target of radiotherapy in pancreatic adenocarcinoma

In pancreatic cancer, methyltransferase-like 3 (METTL3), a N(6)-methyladenosine (m6A) methyltransferase, has a favorable effect on tumors and is a risk factor for patients' prognosis. However, the details of what genes are regulated by METTL3 remain unknown. Several RNAs are methylated, and what genes are favored in pancreatic cancer remains unclear. By epitranscriptomic analysis, we report that polo-like kinase 1 (PLK1) is an important hub gene defining patient prognosis in pancreatic cancer and that RNA methylation is involved in regulating its cell cycle-specific expression. We found that insulin like growth factor 2 mRNA binding protein 2 (IGF2BP2) binds to m6A of PLK1 3' untranslated region and is involved in upregulating PLK1 expression and that demethylation of this site activates the ataxia telangiectasia and Rad3-related protein pathway by replicating stress and increasing mitotic catastrophe, resulting in increased radiosensitivity. This suggests that PLK1 methylation is essential for cell cycle maintenance in pancreatic cancer and is a new therapeutic target.

Direct observation of DNA alterations induced by a DNA disruptor

DNA alterations, such as base modifications and mutations, are closely related to the activity of transcription factors and the corresponding cell functions; therefore, detection of DNA alterations is important for understanding their relationships. Particularly, DNA alterations caused by exposure to exogenous molecules, such as nucleic acid analogues for cancer therapy and the corresponding changes in cell functions, are of interest in medicine for drug development and diagnosis purposes. However, detection of comprehensive direct evidence for the relationship of DNA modifications/mutations in genes, their effect on transcription factors, and the corresponding cell functions have been limited. In this study, we utilized a single-molecule electrical detection method for the direct observation of DNA alterations on transcription factor binding motifs upon exposure to a nucleic acid analogue, trifluridine (FTD), and evaluated the effects of the DNA alteration on transcriptional activity in cancer cell line cells. We found ~ 10% FTD incorporation at the transcription factor p53 binding regions in cancer cells exposed to FTD for 5 months. Additionally, through single-molecule analysis of p53-enriched DNA, we found that the FTD incorporation at the p53 DNA binding regions led to less binding, likely due to weaken the binding of p53. This work suggests that single-molecule detection of DNA sequence alterations is a useful methodology for understanding DNA sequence alterations.

Computational healthcare: Present and future perspectives (Review)

Artificial intelligence (AI) has been developed through repeated new discoveries since around 1960. The use of AI is now becoming widespread within society and our daily lives. AI is also being introduced into healthcare, such as medicine and drug development; however, it is currently biased towards specific domains. The present review traces the history of the development of various AI-based applications in healthcare and compares AI-based healthcare with conventional healthcare to show the future prospects for this type of care. Knowledge of the past and present development of AI-based applications would be useful for the future utilization of novel AI approaches in healthcare.

Scent test using Caenorhabditis elegans to screen for early-stage pancreatic cancer

Although early detection and diagnosis are indispensable for improving the prognosis of patients with pancreatic cancer, both have yet to be achieved. Except for pancreatic cancer, other cancers have already been screened through scent tests using animals or microorganisms, including Caenorhabditis elegans. While such a method may greatly improve the prognosis of pancreatic cancer, no studies have investigated the same, mainly given the difficulty of collecting suitable samples from patients with early-stage pancreatic cancer. In this study, we organized a nationwide study group comprising high-volume centers throughout Japan to collect patients with very-early-stage pancreatic cancer (stage 0 or IA). We initially performed an open-label study involving 83 cases (stage 0–IV), with subsequent results showing significant differences after surgical removal in stage 0–IA (×10 dilution: p < 0.001; ×100 dilution: p < 0.001). Thereafter, a blinded study on 28 cases (11 patients with stage 0 or IA disease and 17 healthy volunteers) was conducted by comparing very-early-stage pancreatic cancer patients with healthy volunteers to determine whether C. elegans could detect the scent of cancer for the diagnosis of early-stage pancreatic cancer. Preoperative urine samples had a significantly higher chemotaxis index compared to postoperative samples in patients with pancreatic cancer [×10 dilution: p < 0.001, area under the receiver operating characteristic curve (AUC) = 0.845; ×100 dilution: p < 0.001, AUC = 0.820] and healthy volunteers (×10 dilution: p = 0.034; ×100 dilution: p = 0.088). Moreover, using the changes in preoperative and postoperative chemotaxis index, this method had a higher sensitivity for detecting early pancreatic cancer compared to existing diagnostic markers. The clinical application C. elegans for the early diagnosis of cancer can certainly be expected in the near future.

Cryptic species in a Vulnerable seabird: shorttailed albatross consists of two species

The occurrence of cryptic species within a threatened taxon is rare, but where they do occur, understanding species boundaries is essential for planning an effective conservation strategy. The short-tailed albatross Phoebastria albatrus is a Vulnerable seabird that mainly breeds on Torishima and the Senkaku Islands in the western North Pacific. Although it has been tacitly regarded as a single management unit with 2 breeding sites, the species is known to comprise 2 genetically separated populations (Senkaku-type and Torishima-type). However, morphological examination of birds from both populations has not been conducted owing to the difficulty in accessing the Senkaku Islands. In this study, we examined the morphological differences between immigrants from the Senkaku Islands to Torishima (Senkaku-type) and native birds on Torishima (Torishima-type) and found significant differences in morphological characteristics between the 2 bird types. In general, Torishima-type birds were larger than Senkaku-type birds, whereas Senkaku-type birds had relatively longer beaks. Based on the morphological differences found in this study as well as genetic and ecological differences revealed in previous studies, we believe that Senkaku- and Torishima-type birds should be classified as different cryptic species. To the best of our knowledge, this is the first case of cryptic species being identified in a threatened avian species.

A Four-Dimensional Organoid System to Visualize Cancer Cell Vascular Invasion

Simple Summary

Using vascular organoid culture with collagen microfiber, we have established a method for culturing organoids that recapitulates the vascular invasion process of cancer cells. This culture model made it possible to four-dimensionally evaluate the dynamics of cancer cells infiltrating into blood vessels.

Abstract

Vascular invasion of cancer is a critical step in cancer progression, but no drug has been developed to inhibit vascular invasion. To achieve the eradication of cancer metastasis, elucidation of the mechanism for vascular invasion and the development of innovative treatment methods are required. Here, a simple and reproducible vascular invasion model is established using a vascular organoid culture in a fibrin gel with collagen microfibers. Using this model, it was possible to observe and evaluate the cell dynamics and histological positional relationship of invasive cancer cells in four dimensions. Cancer-derived exosomes promoted the vascular invasion of cancer cells and loosened tight junctions in the vascular endothelium. As a new evaluation method, research using this vascular invasion mimic model will be advanced, and applications to the evaluation of the vascular invasion suppression effect of a drug are expected.

Abstract 2150: CD103+ tumor infiltrating lymphocytes predict a favorable prognosis in human colorectal cancer

Background: Given that immune system maintains homeostasis by excluding tumors with mutations, in recent years has been proposed the "cancer-immunoediting" hypothesis, which divides immune responses into three phases, i.e., exclusion, equilibrium, and escape. This equilibrium phase takes likely several decades in human life, during the occurrence of mutations and growth of tumors. Recent studies have emerged that the resident memory T cells (Trm) exclusively survey the transformation of normal tissues in equilibrium phase, though reported were other two memory T subsets in extra-epithelial organs, such as central memory T (Tcm) and effector memory T (Tem) cells. Notably, Trm does not exit into blood circulation, instead exerts powerful ant-tumor functions as tumor infiltrating T cells (TIL), by the expression of unique molecules such as CD69 and CD103; CD69 restricts residence in epithelial tissues, and CD103 bounds to a cognate ligand, epithelial E-cadherin, to stimulate antitumor effect.

Purpose: Although previous reports suggested Trm involvement in several tumors, the significance of Trm in predictive patient prognosis of gastrointestinal cancer remains to be investigated fully. Here we study the significance of Trm in colorectal cancer.

Materials and Methods: All available patients of hundred-twenty patients with colorectal cancer in Osaka University Hospital were enrolled in this study during 2012 to 2013, under the agreement of written informed consents; the study was performed according to the approval of institutional ethical committee. Immunohistochemistry by staining tissue samples from surgically resected specimens was performed to identify the cellular distribution, number and expression intensity of CD103+/CD69+ in CD8+ lymphocytes, infiltrated in colorectal cancer tissues. Kaplan-Meier analysis and Cox proportional hazards regression models were applied to predict overall and recurrence-free survival in all patients with colorectal cancer examined.

Result: The staining of Trm, i.e., intratumor CD103+/CD69+/CD8+ TILs represented a favorable prognostic predictor of overall and recurrence-free survival (p&lt;0.05). Indeed, CD103+ TILs were positively associated with the expression of E-cadherin in intratumor regions of colorectal cancer tissues.

Conclusions: The present study suggests that Trm has a significant role in tumor immunity by expressing CD103 in intratumor regions of colorectal cancer tissues, indicating that CD103+ TILs will be useful for the prediction of patient' survival after surgery of colorectal cancer.

Citation Format: Masatoshi Kitakaze, Masamitsu Konno, Taroh Satoh, Tsunekazu Mizushima, Yuichiro Doki, Hideshi Ishii. CD103+ tumor infiltrating lymphocytes predict a favorable prognosis in human colorectal cancer [abstract]. In: Proceedings of the Annual Meeting of the American Association for Cancer Research 2020; 2020 Apr 27-28 and Jun 22-24. Philadelphia (PA): AACR; Cancer Res 2020;80(16 Suppl):Abstract nr 2150.

Immuno-Surgical Management of Pancreatic Cancer with Analysis of Cancer Exosomes

Exosomes (EXs), a type of extracellular vesicles secreted from various cells and especially cancer cells, mesenchymal cells, macrophages and other cells in the tumor microenvironment (TME), are involved in biologically malignant behaviors of cancers. Recent studies have revealed that EXs contain microRNAs on their inside and express proteins and glycolipids on their outsides, every component of which plays a role in the transmission of genetic and/or epigenetic information in cell-to-cell communications. It is also known that miRNAs are involved in the signal transduction. Thus, EXs may be useful for monitoring the TME of tumor tissues and the invasion and metastasis, processes that are associated with patient survival. Because several solid tumors secrete immune checkpoint proteins, including programmed cell death-ligand 1, the EX-mediated mechanisms are suggested to be potent targets for monitoring patients. Therefore, a companion therapeutic approach against cancer metastasis to distant organs is proposed when surgical removal of the primary tumor is performed. However, EXs and immune checkpoint mechanisms in pancreatic cancer are not fully understood, we provide an update on the recent advances in this field and evidence that EXs will be useful for maximizing patient benefit in precision medicine.

Hereditary pancreatitis model by blastocyst complementation in mouse

The application of pluripotent stem cells is expected to contribute to the elucidation of unknown mechanism of human diseases. However, in vitro induction of organ-specific cells, such as pancreas and liver, is still difficult and the reproduction of their disorders in a model has been unfeasible. To study the mechanism of human hereditary pancreatitis (HP), we here performed the blastocyst complementation (BC) method. In the BC method, mouse embryonic stem (ES) cells harboring CRISPR/CAS9-mediated mutations in the Prss1 gene were injected into blastocysts with deficient Pdx1 gene, which is a critical transcription factor in the development of pancreas. The results showed that trypsin was activated extremely in Prss1-mutant mice. 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.

Convolutional Neural Network Can Recognize Drug Resistance of Single Cancer Cells

It is known that single or isolated tumor cells enter cancer patients' circulatory systems. These circulating tumor cells (CTCs) are thought to be an effective tool for diagnosing cancer malignancy. However, handling CTC samples and evaluating CTC sequence analysis results are challenging. Recently, the convolutional neural network (CNN) model, a type of deep learning model, has been increasingly adopted for medical image analyses. However, it is controversial whether cell characteristics can be identified at the single-cell level by using machine learning methods. This study intends to verify whether an AI system could classify the sensitivity of anticancer drugs, based on cell morphology during culture. We constructed a CNN based on the VGG16 model that could predict the efficiency of antitumor drugs at the single-cell level. The machine learning revealed that our model could identify the effects of antitumor drugs with ~0.80 accuracies. Our results show that, in the future, realizing precision medicine to identify effective antitumor drugs for individual patients may be possible by extracting CTCs from blood and performing classification by using an AI system.

COVID-19 Drug Discovery Using Intensive Approaches

Since the infectious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) was reported in China during December 2019, the coronavirus disease 2019 (COVID-19) has spread on a global scale, causing the World Health Organization (WHO) to issue a warning. While novel vaccines and drugs that target SARS-CoV-2 are under development, this review provides information on therapeutics which are under clinical trials or are proposed to antagonize SARS-CoV-2. Based on the information gained from the responses to other RNA coronaviruses, including the strains that cause severe acute respiratory syndrome (SARS)-coronaviruses and Middle East respiratory syndrome (MERS), drug repurposing might be a viable strategy. Since several antiviral therapies can inhibit viral replication cycles or relieve symptoms, mechanisms unique to RNA viruses will be important for the clinical development of antivirals against SARS-CoV-2. Given that several currently marketed drugs may be efficient therapeutic agents for severe COVID-19 cases, they may be beneficial for future viral pandemics and other infections caused by RNA viruses when standard treatments are unavailable.

One-carbon metabolism for cancer diagnostic and therapeutic approaches

Altered metabolism is critical for the rapid and unregulated proliferation of cancer cells; hence the requirement for an abundant source of nucleotides. One characteristic of this metabolic reprogramming is in one-carbon (1C) metabolism, which is particularly noteworthy for its role in DNA synthesis. Various forms of methylation are also noteworthy as they relate to cancer cell survival and proliferation. In recent years, 1C metabolism has received substantial attention for its role in cancer malignancy via these functions. Therefore, therapeutic inhibitors targeting 1C metabolism have been utilized as anticancer drugs. This review outlines the importance of 1C metabolism and its clinical application in cancer. Understanding 1C metabolism could aid the development of novel cancer diagnostic and therapeutic methods.

CD44/CD133-Positive Colorectal Cancer Stem Cells are Sensitive to Trifluridine Exposure

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.

Application of C. elegans cancer screening test for the detection of pancreatic tumor in genetically engineered mice

Pancreatic ductal adenocarcinoma (PDAC) exhibits a very early onset of metastasis. Thus, early detection and treatment are pivotal to successful eradication of pancreatic cancers. Economical and non-invasive cancer screening systems is indispensable for this purpose. Previously our group developed a novel method to detect various kinds of human cancer using nematode Caenorhabditis elegans (C. elegans) that respond to cancer odor in urine; however, whether this method is useful for non-human species remains to be understood. In this study, we examined its effectiveness in the detection of murine pancreatic tumor spontaneously generated in genetically-engineered mice. We generated pancreas-specific Kras ^G12D and/or c-Met deletion mutant mice and measured the probability of spontaneous tumor generation in these mice. The chemotactic indexes of C. elegans to the urine samples of these mutant mice were measured. As previously described, oncogenic Kras^G12D was necessary to induce pancreatic intraepithelial neoplasia in this mouse model, while c-Met mutation did not show further effect. The chemotactic analysis indicated that C. elegans avoids urine of healthy recipient mice, while they tended to be attracted to urine of mice with Kras^G12D . Our study demonstrated that C. elegans can recognize the odor of pancreatic cancer in urine of Kras^G12D model mouse, suggesting the similarity of cancer odor between species. Our result facilitates further studies on mechanism of cancer detection by C. elegans.

Distinct methylation levels of mature microRNAs in gastrointestinal cancers

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.

Reproducibility of CRISPR-Cas9 methods for generation of conditional mouse alleles: a multi-center evaluation

BACKGROUND

CRISPR-Cas9 gene-editing technology has facilitated the generation of knockout mice, providing an alternative to cumbersome and time-consuming traditional embryonic stem cell-based methods. An earlier study reported up to 16% efficiency in generating conditional knockout (cKO or floxed) alleles by microinjection of 2 single guide RNAs (sgRNA) and 2 single-stranded oligonucleotides as donors (referred herein as "two-donor floxing" method).

RESULTS

We re-evaluate the two-donor method from a consortium of 20 laboratories across the world. The dataset constitutes 56 genetic loci, 17,887 zygotes, and 1718 live-born mice, of which only 15 (0.87%) mice contain cKO alleles. We subject the dataset to statistical analyses and a machine learning algorithm, which reveals that none of the factors analyzed was predictive for the success of this method. We test some of the newer methods that use one-donor DNA on 18 loci for which the two-donor approach failed to produce cKO alleles. We find that the one-donor methods are 10- to 20-fold more efficient than the two-donor approach.

CONCLUSION

We propose that the two-donor method lacks efficiency because it relies on two simultaneous recombination events in cis, an outcome that is dwarfed by pervasive accompanying undesired editing events. The methods that use one-donor DNA are fairly efficient as they rely on only one recombination event, and the probability of correct insertion of the donor cassette without unanticipated mutational events is much higher. Therefore, one-donor methods offer higher efficiencies for the routine generation of cKO animal models.

Significant epitranscriptomes in heterogeneous cancer

Precision medicine places significant emphasis on techniques for the identification of DNA mutations and gene expression by deep sequencing of gene panels to obtain medical data. However, other diverse information that is not easily readable using bioinformatics, including RNA modifications, has emerged as a novel diagnostic and innovative therapy owing to its multifunctional aspects. It is suggested that this breakthrough innovation might open new avenues for the elucidation of uncharacterized cancer cellular functions to develop more precise medical applications. The functional characteristics and regulatory mechanisms of RNA modifications, ie, the epitranscriptome (ETR), which reflects RNA metabolism, remains unclear, mainly due to detection methods being limited. Recent studies have revealed that N6‐methyl adenosine, the most common modification in mRNA in eukaryotes, is affected in various types of cancer and, in some cases, cancer stem cells, but also affects cellular responses to viral infections. The ETR can control cancer cell fate through mRNA splicing, stability, nuclear export, and translation. Here we report on the recent progress of ETR detection methods, and biological findings regarding the significance of ETR in cancer precision medicine.

Beam Energy and Centrality Dependence of Direct-Photon Emission from Ultrarelativistic Heavy-Ion Collisions

The PHENIX collaboration presents first measurements of low-momentum (0.4<p_{T}<3  GeV/c) direct-photon yields from Au+Au collisions at sqrt[s_{NN}]=39 and 62.4 GeV. For both beam energies the direct-photon yields are substantially enhanced with respect to expectations from prompt processes, similar to the yields observed in Au+Au collisions at sqrt[s_{NN}]=200. Analyzing the photon yield as a function of the experimental observable dN_{ch}/dη reveals that the low-momentum (>1  GeV/c) direct-photon yield dN_{γ}^{dir}/dη is a smooth function of dN_{ch}/dη and can be well described as proportional to (dN_{ch}/dη)^{α} with α≈1.25. This scaling behavior holds for a wide range of beam energies at the Relativistic Heavy Ion Collider and the Large Hadron Collider, for centrality selected samples, as well as for different A+A collision systems. At a given beam energy, the scaling also holds for high p_{T} (>5  GeV/c), but when results from different collision energies are compared, an additional sqrt[s_{NN}]-dependent multiplicative factor is needed to describe the integrated-direct-photon yield.

Abstract 2963: CD44+/CD133+ colorectal cancer stem cells are sensitive to trifluridine

Background: Cancer stem cells (CSCs) are involved in disease recurrence, metastases, and therapeutic resistance. However, anticancer agents that target CSCs are not currently available. Trifluridine (FTD)/tipiracil (TPI), a novel oral antitumor drug, was approved for the treatment of patients with metastatic colorectal cancer who had been previously treated with anti-vascular endothelial growth factors; anti-epidermal growth factor receptors (in patients with ras wild-type genes); or fluoropyrimidine-, oxaliplatin-, irinotecan-based chemotherapies. FTD/TPI improves overall survival, and FTD is the key component of FTD/TPI. Here, we demonstrated the efficacy of FTD against CD44 and CD133 high-expressing (CD44+CD133+) colorectal cancer cells that possess CSC-like properties.

Method: CD44+CD133+ and other populations of DLD-1, a colorectal cell line, were separated by fluorescence-activated cell sorting (FACS). The sphere-forming activity of each population, and anti- sphere-forming effects of FTD and fluorouracil (5-FU) on CD44+CD133+ cells, were measured. In addition, DLD-1 and HCT-116, two colorectal cell lines, were treated with FTD for 5 months. The CSC markers CD44 and CD133 were measured by FACS, and the cells' in vitro and in vivo tumor-initiating properties were evaluated.

Results: CD44+CD133+ DLD-1 cells formed significantly more spheres than did CD44-CD133- cells (sphere ratio CD44+CD133+/CD44-CD133- = 4.0) and CD44+CD133- cells (sphere ratio CD44+CD133+/CD44+CD133- = 1.7). In the in vitro proliferation assay, CD44+CD133+ cells had greater 5-FU resistance, but not higher FTD resistance, than did unsorted cells. In addition, treatment of CD44+CD133+ DLD-1 cells with subtoxic concentrations of FTD (1 µM) disrupted sphere formation, which was superior to the effect of treatment with 1 µM 5-FU. The inhibition rates for FTD and 5-FU were 59.5% and 14.3%, respectively. DLD-1 and HCT-116 cell lines treated with FTD for 5 months had smaller CD44+CD133+ populations and lower sphere-forming activity than did untreated cell lines; population decline rates were 93.8% and 74.7%, respectively. Furthermore, 5 months of in vitro exposure to FTD reduced in vivo tumor formation potential in both cell lines. These results suggest that FTD is effective against CSC-like cells, and that treatment with FTD might reduce CSC-like populations.

Conclusion: FTD had a direct effect on the sphere-forming activity of CSC-like CD44+CD133+ cells that was superior to that of treatment with 5-FU. Its effectiveness against CSC-like CD44+CD133+ cells suggests that FTD might be useful for CSC-targeted chemotherapy in tumors that highly express CD44 and CD133.

Citation Format: Kenta Tsunekuni, Masamitsu Konno, Jun Koseki, Ayumu Asai, Kazuaki Matsuoka, Teiji Takechi, Yuichiro Doki, Masaki Mori, Hideshi Ishii. CD44+/CD133+ colorectal cancer stem cells are sensitive to trifluridine [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 2963.

Mitochondrial pyruvate carrier 1 expression controls cancer epithelial-mesenchymal transition and radioresistance

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.

Computational analyses for cancer biology based on exhaustive experimental backgrounds

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.

Drug discovery of anticancer drugs targeting methylenetetrahydrofolate dehydrogenase 2

Many anticancer drugs have serious adverse effects; therefore, it is necessary to target features specific to cancer cells to minimize the effects on healthy cells. Methylenetetrahydrofolate dehydrogenase 2 (MTHFD2) was reported to be specifically enhanced in cancer. We confirmed the validity of MTHFD2 as a drug discovery target using clinical data. In addition, we performed in silico screening to design an anticancer drug specifically targeting MTHFD2. Analysis of the clinical data indicated that MTHFD2 was enhanced in most cancers compared with normal tissues, and affected the prognosis in cancer patients. Candidate compounds for MTHFD2 inhibitors were identified using in silico drug discovery techniques, and the important interactions for MTHFD2 binding were determined. In addition, these candidate compounds decreased levels of MTHFD2 metabolites in cancer cells. The findings of the present study may help to develop anticancer drugs targeting MTHFD2, with a view to minimizing the adverse effects of anticancer drugs.

A Convolutional Neural Network Uses Microscopic Images to Differentiate between Mouse and Human Cell Lines and Their Radioresistant Clones

: 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.

Carbon ion beam radioresistant rodent cells are sensitized to trifluorothymidine exposure

Although charged particle therapy, including carbon ion beam radiation, is a cutting-edge technology in human cancer treatment, the molecular mechanisms underlying cellular resistance to this type of therapy remain unknown. Furthermore, the chemotherapeutic agents that are most effective at overcoming cellular resistance remain unknown. In the present study, carbon ion beam radioresistant rodent cells were developed and their sensitization to trifluorothymidine (FTD), a derivative of deoxythymidine, was studied. The results of the present study demonstrated that carbon ion beam radioresistant cells were more sensitive to FTD compared with X-ray radioresistant cells. The results of the present study suggested that FTD is involved in carbon ion beam radioresistance, encouraging further study of cellular resistance to charged particle therapy for refractory human cancer.

Poly(ethylene glycol)-poly(lysine) block copolymer-ubenimex conjugate targets aminopeptidase N and exerts an antitumor effect in hepatocellular carcinoma stem cells

Previous studies highlighted that aminopeptidase N (APN)/CD13 acts as a scavenger in the survival of hepatocellular carcinoma (HCC) stem cells by reducing reactive oxygen species (ROS) levels. Hence, it has been proposed that APN/CD13 inhibition can increase cellular ROS levels and sensitize cells to chemotherapeutic agents. Although ubenimex, also known as bestatin, competitively inhibits proteases such as APN/CD13 on the cellular membrane and it is clinically used for patients with acute myeloid leukemia and lymphedema, research has demonstrated that higher concentrations of the agent induce the death of APN/CD13⁺ HCC stem cells. In this study, we developed a poly(ethylene glycol)-poly(lysine) block copolymer-ubenimex conjugate (PEG-b-PLys(Ube)) to increase the efficacy of reagents in APN/CD13⁺ cancer stem cells. Exposure to PEG-b-PLys(Ube) increased the intracellular ROS concentration by inhibiting APN enzyme activity, permitting the induction of apoptosis and attenuation of HCC cell proliferation. In addition, PEG-b-PLys(Ube) exhibited a relatively stronger antitumor effect in mice than PEG-b-PLys alone or phosphate-buffered saline. Moreover, an isobologram analysis revealed that combinations of fluorouracil, cisplatin, or doxorubicin with PEG-b-PLys(Ube) exhibited synergistic effects. This study demonstrated that PEG-b-PLys(Ube) does not impair the properties of ubenimex and exerts a potent antitumor effect.

Abstract 2859: Deep learning recognizes FTD-resistant isolated cancer cells of colon cancer

In recent years, innovative technologies that extract feature descriptions from the large volume of data on speech recognition, visual object recognition and detection as well as many other domains, such as drug discovery and DNA sequence annotations by deep learning techniques and applying them to automatic recognition etc. are drawing attention. As cancer research aiming at applying deep learning techniques to cases that are resistant to surgical therapy and drug therapy in metastatic colorectal cancer, we developed a fundamental technology that can predict the resistance of free cancer cells to fluorinated pyrimidine anticancer drugs by deep learning from the morphological image data taken from images. An experimental model was used in our investigation in order to clarify whether or not its image recognition ability can be applied to the determination of drug resistance of free cancer cells circulating in the peripheral blood. That is, a cell line established by inducing a resistance to FTD or 5 FU added to the cell culture solution was prepared over several months and the ability to recognize the tolerance of the drug was examined from a large volume of image data, and it was shown that it can be distinguished dominantly in a short-term culture system. Further, as a result of examination after separation at the single cell level, it was possible to distinguish fluorescent-labeled resistant strains dominantly. In addition, we were able to recognize the drug resistance character well by injecting resistant strains intravenously into the mice to prepare a model of free cancer cells and collecting circulating free cancer cells. Moreover, as a pre-clinical model, resistant strains were mixed with susceptible strains at various ratios and transplanted into mice and experimented. As a result, the nature of the resistance to treatment was predicted by image recognition, and death of the mice due to cancer was well correlated with the malignant trait of drug-resistant cancer cells. Then, by linking the feature expression obtained from the image and the Omics data, a detailed stratification of treatment resistance was possible. From the above, a technique in the mouse that can distinguish free cancer cells collected from the peripheral blood by deep learning of images was constructed, and a foundation to be applied to medical treatment and precision medical care in the future was established.

Citation Format: Kiminori Yanagisawa, Masamitsu Konno, Masayasyu Toratani, Hirohiko Niioka, Ayumu Asai, Jun Koseki, Kenta Tsunekuni, Taroh Satoh, Kazuhiko Ogawa, Jun Miyake, Yuichiro Doki, Masaki Mori, Hideshi Ishii. Deep learning recognizes FTD-resistant isolated cancer cells of colon cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2859.

Abstract 5164: Mechanosensor MYL9 regulates cancer cell malignancy in gastrointestinal tumors

Although the stiffness of tissues likely is involved in the malignant behavior of tumors, it remains to be clarified which molecules control the nature, how it is involved in the invasiveness of tumors, or whether any marker is available for the prediction of cancer patient prognosis. In the present study, we studied the role of Myl9, a non-muscle-type, myosin light chain by the experiment in vitro, and assessed the usefulness in the stratification of patients in vivo as the precision medicine. Given that Myl9 is involved in the contraction of cell skeleton, cell hardness, and alterations of cell morphology in various tissues, we first examined whether the expression of the Myl9 is associated with the clinical status of tumors by immunohistochemistry. The results of 45 cases with colon cancer and pancreatic cancer indicated that the increased expression of Myl9 is associated significantly with a reduced provability of overall survival and disease-free survival of those cancers. Moreover, we noted the differential expression of Myl9 in epithelial cancer cells and mesenchymal fibroblasts, i.e., the accumulation of Myl9 staining in cell nuclei of fibroblasts. The experiment of 3-dimensional culture with cancer cells and fibroblasts confirmed the results. Furthermore, we investigated whether Myl9 overexpression is involved in the biologic behavior of gastrointestinal cancer cells. The results showed that the rentiviral-mediated overexpression of Myl9 resulted in an increase of cell proliferation and invasion as well as tumorigenicity in mice. The present study indicates that Myl9 protein can play a fundamental role in the malignant behaviors of gastrointestinal cancer cells.

Citation Format: Masamitsu Konno, Kiminori Yanagisawa, Katsunori Matsushita, Ayumu Asai, Jun Koseki, Michiya Matsusaki, Shinji Deguchi, Yuichiro Doki, Masaki Mori, Hideshi Ishii. Mechanosensor MYL9 regulates cancer cell malignancy in gastrointestinal tumors [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 5164.

Abstract 2890: Trifluridine efficacy in cancer stem cell

Background: Cancer stem cells (CSC) have been involved in disease recurrence, metastasis, and therapeutic resistance, but effective anti-cancer agent for these cells is not still currently available. Trifluridine (FTD) is a key component of the novel oral antitumor drug trifluridine/tipiracil, which was approved for the treatment of patients with metastatic colorectal cancer who have been previously treated with fluoropyrimidine, oxaliplatin and irinotecan based chemotherapy etc. and improved overall survival. Here we showed the efficacy of FTD in CD44 and CD133 high expressing (CD44high/CD133high) cancer cells which has CSC like property.

Method: CD44high /CD133high and CD44low /CD133low DLD-1 cells were separated by Fluorescence-Activated Cell Sorting (FACS) and subjected to sphere formation assay. Anti-proliferative and anti-sphere forming effects of FTD in CD44high /CD133high cells were measured. Then, 150 days FTD long exposed colorectal cell line's CSC markers CD44 and CD133 were measured by flow cytometry and its tumor initiating property in in vitro and in vivo were evaluated.

Results: CD44 high /CD133 high DLD-1 cells formed much more sphere than CD44low /CD133low cells significantly. Compared to unsorted cells, CD44high /CD133high cells displayed 5-FU resistance (IC50 value of 5-FU for unsorted and CD44 high /CD133 high cells were 2.5 μM and 5.5 μM respectively) but not FTD resistance (IC50 value of FTD for unsorted and CD44 high /CD133 high cells were 8.9 μM and 10.7 μM, respectively) in in vitro proliferation assay. In addition, FTD treatment in a subtoxic concentration 1 μM for DLD-1 cells disrupted sphere formation. FTD-long exposed DLD-1 cell lines showed decreased CD44high /CD133high population compared to its parental cell line from 11.3% to 0.7%, and showed decreased sphere-forming efficacy. In addition, FTD-long exposed DLD-1 cell lines decreased tumor forming potential in in vivo. These results suggest that FTD is effective for CSC like cells and that long exposure to FTD might lead CSC depletion.

Conclusion: FTD was proved to be effective for CSC like CD44high /CD133high cells. It suggests that FTD might be useful for CSC targeted chemotherapy in case of CD44 and CD133 are highly expressed subtype of tumors.

Citation Format: Kenta Tsunekuni, Masamitsu Konno, Jun Koseki, Ayumu Asai, Yuichiro Doki, Masaki Mori, Hideshi Ishii. Trifluridine efficacy in cancer stem cell [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2018; 2018 Apr 14-18; Chicago, IL. Philadelphia (PA): AACR; Cancer Res 2018;78(13 Suppl):Abstract nr 2890.

Cell-free culture conditioned medium elicits pancreatic β cell lineage-specific epigenetic reprogramming in mice

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.

The mitochondrial one-carbon metabolic pathway is associated with patient survival in pancreatic cancer

The expression levels of one-carbon metabolic enzymes were investigated and observed to be correlated with clinicopathological parameters in patients with pancreatic cancer. Mitochondrial one-carbon metabolism comprises a network of biological reactions that integrate nutrient status with nucleotide synthesis, amino acid metabolism, antioxidant reduced nicotinamide adenine dinucleotide phosphate production and epigenetic methylation processes. Previous studies have reported that the hyper-activation of mitochondrial one-carbon metabolism serves a significant role in malignant cancer phenotypes. A total of 103 patients underwent surgical resection of pancreatic ductal adenocarcinomas (PDAC) at Osaka University Hospital between April 2007 and December 2013 and were enrolled in this study. Subsequently, the expression of the one-carbon metabolic enzymes methylenetetrahydrofolate dehydrogenase 2 (MTHFD2), aldehyde dehydrogenase 1 family member L2 (ALDH1L2), and serine hydroxymethyltransferase (SHMT2) was examined using immunohistochemical analysis. The immunohistochemical analyses demonstrated that patients with high expression levels of MTHFD2, ALDH1L2 or SHMT2 had significantly poor overall survival (OS) and disease-free survival (DFS) rates, as compared with patients with low expression levels. Furthermore, multivariate Cox proportional hazards analysis indicated that MTHFD2 and ALDH1L2 were independent prognostic factors for OS and DFS, whereas SHMT2 was not predictive of DFS. However, high and low expression levels of all three folate metabolic enzymes were significantly associated with improved OS and DFS, compared with the high expression of one or two folate metabolic enzymes. The expression levels of mitochondrial one-carbon metabolic enzymes are independent prognostic factors and potential therapeutic targets for future pancreatic cancer treatments.

c-Met affects gemcitabine resistance during carcinogenesis in a mouse model of pancreatic cancer

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.

Association of iron metabolic enzyme hepcidin expression levels with the prognosis of patients with 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<0.0001, and P=0.0056, respectively). Thus, hepcidin and ferroportin expressions might be novel prognostic indicators for pancreatic cancer.

Fetal hepatocyte-derived culture medium elicits adipocyte differentiation to bile duct cell lineages in a mouse model

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.

Oncogene c-Myc promotes epitranscriptome m6A reader YTHDF1 expression in colorectal cancer

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 (m6A) 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.

Computational trans-omics approach characterised methylomic and transcriptomic involvements and identified novel therapeutic targets for chemoresistance in gastrointestinal cancer stem cells

We investigated the relationship between methylomic [5-methylation on deoxycytosine to form 5-methylcytosine (5mC)] and transcriptomic information in response to chemotherapeutic 5-fluorouracil (5-FU) exposure and cisplatin (CDDP) administration using the ornithine decarboxylase (ODC) degron-positive cancer stem cell model of gastrointestinal tumour. The quantification of 5mC methylation revealed various alterations in the size distribution and intensity of genomic loci for each patient. To summarise these alterations, we transformed all large volume data into a smooth function and treated the area as a representative value of 5mC methylation. The present computational approach made the methylomic data more accessible to each transcriptional unit and allowed to identify candidate genes, including the tumour necrosis factor receptor-associated factor 4 (TRAF4), as novel therapeutic targets with a strong response to anti-tumour agents, such as 5-FU and CDDP, and whose significance has been confirmed in a mouse model in vivo. The present study showed that 5mC methylation levels are inversely correlated with gene expression in a chemotherapy-resistant stem cell model of gastrointestinal cancer. This mathematical method can be used to simultaneously quantify and identify chemoresistant potential targets in gastrointestinal cancer stem cells.

Mitochondrial pyruvate carrier modulates the epithelial-mesenchymal transition in cholangiocarcinoma

Intrahepatic cholangiocarcinoma (ICC) is known to have a high malignant potential. Because of its high recurrence rate, ICC has a poor prognosis even after complete tumor resection. Compared with normal differentiated cells, cancer cells have an altered metabolism for supporting their survival in severe conditions. Cancer cells acquire additional malignant potential as a result of this metabolic alteration. Thus, the molecules known to be involved in cancer metabolism, could be novel therapeutic targets. The mitochondrial pyruvate carrier (MPC) is a recently discovered pyruvate transporter, which is located in the mitochondrial inner membrane. Although MPC is composed of two subunits, it has been reported that the MPC1 subunit is specifically associated with poor prognosis in several cancers, including colorectal and prostate cancer. However, only a few studies have assessed the clinical significance of MPC1 and the molecular mechanisms underlying its influence on cancer progression are not well understood. This study aimed to clarify the function of MPC1 that affects the malignant potential of ICC. The expression of MPC1 in ICC clinical specimens was determined by immunohistochemistry. In addition, the correlations between MPC1 expression and the survival rate, as well as various clinicopathological parameters were assessed. Low MPC1 expression correlated with poor ICC prognosis and was correlated with tumor invasion and distant metastasis. Both these phenomena are closely associated with the epithelial-mesenchymal transition (EMT). Therefore, we investigated the impact of altering the MPC1 gene expression on the malignant potential of cancer cells using biliary tract cancer cell lines in vitro. The expression of MPC1 was downregulated in the cells induced to undergo EMT following treatment with TGF-β. Furthermore, the inhibition of MPC1 expression induced EMT in cancer cells, and the overexpression of MPC1 suppressed the migration of tumor cells. These results indicated that MPC1 could be a novel therapeutic target in some cancers.

Hypoxia stimulates the cytoplasmic localization of oncogenic long noncoding RNA LINC00152 in colorectal cancer

Recent studies have indicated that long noncoding RNAs (lncRNAs) play a pivotal role in almost all physiological cellular processes, including every stage of cancer development. Given that hypoxia in the tumor microenvironment is involved in the malignant behavior of tumors, such as invasion and metastasis, we investigated the cytoplasmic and nuclear localization of lncRNAs in colorectal cancer cells. A cell culture under hypoxic conditions revealed several lncRNAs, such as LINC00152, whose levels were increased in the cytoplasm of colorectal cancer cells. A database study indicated that LINC00152 shares microRNA-binding sites, such as miR-138 and miR-193, with the hypoxia-inducible factor 1 (HIF1), thus suggesting that LINC00152 could possibly function as a competing endogenous RNA that can augment Hif1 translation in the cytoplasm of hypoxic colorectal cancer cells. Moreover, the data presented in the studies of surgically resected samples showed that patients with colorectal cancer exhibiting high LINC00152 expression were associated with a worsened survival rate; this supports the suggested oncogenic function of LINC00152 in the cytoplasm under hypoxic conditions. The present study demonstrated that lncRNA networks could provide diagnostic tools and novel therapeutic targets against colorectal cancer cells.

The epitranscriptome m6A writer METTL3 promotes chemo- and radioresistance in pancreatic cancer cells

N6-methyladenosine (m6A) is the most abundant epitranscriptome modification in mammalian mRNA. Recent years have seen substantial progress in m6A epitranscriptomics, indicating its crucial roles in the initiation and progression of cancer through regulation of RNA stabilities, mRNA splicing, microRNA processing and mRNA translation. However, by what means m6A is dynamically regulated or written by enzymatic components represented by methyltransferase-like 3 (METTL3) and how m6A is significant for each of the numerous genes remain unclear. We focused on METTL3 in pancreatic cancer, the prognosis of which is not satisfactory despite the development of multidisciplinary therapies. We established METTL3-knockdown pancreatic cancer cell line using short hairpin RNA. Although morphologic and proliferative changes were unaffected, METTL3-depleted cells showed higher sensitivity to anticancer reagents such as gemcitabine, 5-fluorouracil, cisplatin and irradiation. Our data suggest that METTL3 is a potent target for enhancing therapeutic efficacy in patients with pancreatic cancer. In addition, we performed cDNA expression analysis followed by gene ontology and protein-protein interaction analysis using the Database for Annotation, Visualization, and Integrated Discovery and Search Tool for the Retrieval of Interacting Genes/Proteins databases, respectively. The results demonstrate that METTL3 was associated with mitogen-activated protein kinase cascades, ubiquitin-dependent process and RNA splicing and regulation of cellular process, suggesting functional roles and targets of METTL3.