M2 macrophage-derived TGF-ß induces age-associated loss of adipogenesis through progenitor cell senescence.

OBJECTIVES: Adipose tissue is an endocrine and energy storage organ composed of several different cell types, including mature adipocytes, stromal cells, endothelial cells, and a variety of immune cells. Adipose tissue aging contributes to the pathogenesis of metabolic dysfunction and is likely induced by crosstalk between adipose progenitor cells (APCs) and immune cells, but the underlying molecular mechanisms remain largely unknown. In this study, we revealed the biological role of p16high senescent APCs, and investigated the crosstalk between each cell type in the aged white adipose tissue. METHODS: We performed the single-cell RNA sequencing (scRNA-seq) analysis on the p16high adipose cells sorted from aged p16-CreERT2/Rosa26-LSL-tdTomato mice. We also performed the time serial analysis on the age-dependent bulk RNA-seq datasets of human and mouse white adipose tissues to infer the transcriptome alteration of adipogenic potential within aging. RESULTS: We show that M2 macrophage-derived TGF-ß induces APCs senescence which impairs adipogenesis in vivo. p16high senescent APCs increase with age and show loss of adipogenic potential. The ligand-receptor interaction analysis reveals that M2 macrophages are the donors for TGF-ß and the senescent APCs are the recipients. Indeed, treatment of APCs with TGF-ß1 induces senescent phenotypes through mitochondrial ROS-mediated DNA damage in vitro. TGF-ß1 injection into gonadal white adipose tissue (gWAT) suppresses adipogenic potential and induces fibrotic genes as well as p16 in APCs. A gWAT atrophy is observed in cancer cachexia by APCs senescence, whose induction appeared to be independent of TGF-ß induction. CONCLUSIONS: Our results suggest that M2 macrophage-derived TGF-ß induces age-related lipodystrophy by APCs senescence. The TGF-ß treatment induced DNA damage, mitochondrial ROS, and finally cellular senescence in APCs.

Wnt/ß-catenin signaling regulates amino acid metabolism through the suppression of CEBPA and FOXA1 in liver cancer cells.

Deregulation of the Wnt/ß-catenin pathway is associated with the development of human cancer including colorectal and liver cancer. Although we previously showed that histidine ammonia lyase (HAL) was transcriptionally reduced by the ß-catenin/TCF complex in liver cancer cells, the mechanism(s) of its down-regulation by the complex remain to be clarified. In this study, we search for the transcription factor(s) regulating HAL, and identify CEBPA and FOXA1, two factors whose expression is suppressed by the knockdown of ß-catenin or TCF7L2. In addition, RNA-seq analysis coupled with genome-wide mapping of CEBPA- and FOXA1-binding regions reveals that these two factors also increase the expression of arginase 1 (ARG1) that catalyzes the hydrolysis of arginine. Metabolome analysis discloses that activated Wnt signaling augments intracellular concentrations of histidine and arginine, and that the signal also increases the level of lactic acid suggesting the induction of the Warburg effect in liver cancer cells. Further analysis reveals that the levels of metabolites of the urea cycle and genes coding its related enzymes are also modulated by the Wnt signaling. These findings shed light on the altered cellular metabolism in the liver by the Wnt/ß-catenin pathway through the suppression of liver-enriched transcription factors including CEBPA and FOXA1.

Integration of Kupffer cells into human iPSC-derived liver organoids for modeling liver dysfunction in sepsis.

Maximizing the potential of human liver organoids (LOs) for modeling human septic liver requires the integration of innate immune cells, particularly resident macrophage Kupffer cells. In this study, we present a strategy to generate LOs containing Kupffer cells (KuLOs) by recapitulating fetal liver hematopoiesis using human induced pluripotent stem cell (hiPSC)-derived erythro-myeloid progenitors (EMPs), the origin of tissue-resident macrophages, and hiPSC-derived LOs. Remarkably, LOs actively promote EMP hematopoiesis toward myeloid and erythroid lineages. Moreover, supplementing with macrophage colony-stimulating factor (M-CSF) proves crucial in sustaining the hematopoietic population during the establishment of KuLOs. Exposing KuLOs to sepsis-like endotoxins leads to significant organoid dysfunction that closely resembles the pathological characteristics of the human septic liver. Furthermore, we observe a notable functional recovery in KuLOs upon endotoxin elimination, which is accelerated by using Toll-like receptor-4-directed endotoxin antagonist. Our study represents a comprehensive framework for integrating hematopoietic cells into organoids, facilitating in-depth investigations into inflammation-mediated liver pathologies.

Genome-wide analysis of DNA methylation in pseudomyxoma peritonei originated from appendiceal neoplasms.

INTRODUCTION: Pseudomyxoma peritonei (PMP) is a disease characterized by progressive accumulation of intraperitoneal mucinous ascites produced by neoplasms in the abdominal cavity. Since the prognosis of patients with PMP remain unsatisfactory, the development of effective therapeutic drug(s) is a matter of pressing concern. Genetic analyses of PMP have clarified the frequent activation of GNAS and/or KRAS. However, the involvement of global epigenetic alterations in PMPs has not been reported. METHODS: To clarify the genetic background of the 15 PMP tumors, we performed genetic analysis using AmpliSeq Cancer HotSpot Panel v2. We further investigated global DNA methylation in the 15 tumors and eight non-cancerous colonic epithelial cells using Methylation EPIC array BeadChip (Infinium 850k) containing a total of 865,918 probes. RESULTS: This is the first report of comprehensive DNA methylation profiles of PMPs in the world. We clarified that the 15 PMPs could be classified into at least two epigenotypes, unique methylation epigenotype (UME) and normal-like methylation epigenotype (NLME), and that genes associated with neuronal development and synaptic signaling may be involved in the development of PMPs. In addition, we identified a set of hypermethylation marker genes such as HOXD1 and TSPYL5 in the 15 PMPs. CONCLUSIONS: These findings may help the understanding of the molecular mechanism(s) of PMP and contribute to the development of therapeutic strategies for this life-threatening disease.

Expression of PVRL4, a molecular target for cancer treatment, is transcriptionally regulated by FOS.

PVRL4 (or nectin­4) is a promising therapeutic target since its upregulated expression is found in a wide range of human cancer types. Enfortumab vedotin, an antibody­drug conjugate targeting PVRL4, is clinically used for the treatment of urothelial bladder cancer. In addition, rMV­SLAMblind, a genetically engineered oncolytic measles virus, can infect cancer cells and induce apoptosis through interaction with PVRL4. Although PVRL4 transcript levels are elevated in breast, lung and ovarian cancer, the mechanisms of its upregulation have not yet been uncovered. To clarify the regulatory mechanisms of elevated PVRL4 expression in breast cancer cells, Assay for Transposase­Accessible Chromatin­sequencing and chromatin immunoprecipitation­sequencing (ChIP­seq) data were used to search for its regulatory regions. Using breast cancer cells, an enhancer region was ultimately identified. Additional analyses, including ChIP and reporter assays, demonstrated that FOS interacted with the PVRL4 enhancer region, and that alterations of the FOS­binding motifs in the enhancer region decreased reporter activity. Consistent with these data, exogenous expression of FOS enhanced the reporter activity and PVRL4 expression in breast cancer cells. Furthermore, RNA­seq analysis using breast cancer cells treated with PVRL4 small interfering RNA revealed its possible involvement in the cytokine response and immune system. These data suggested that FOS was involved, at least partly, in the regulation of PVRL4 expression in breast cancer cells, and that elevated PVRL4 expression may regulate the response of cancer cells to cytokines and the immune system.

Aberrant monocytopoiesis drives granuloma development in sarcoidosis.

In sarcoidosis, granulomas develop in multiple organs including the liver and lungs. Although mechanistic target of rapamycin complex 1 (mTORC1) activation in macrophages drives granuloma development in sarcoidosis by enhancing macrophage proliferation, little is known about the macrophage subsets that proliferate and mature into granuloma macrophages. Here, we show that aberrantly increased monocytopoiesis gives rise to granulomas in a sarcoidosis model, in which Tsc2, a negative regulator of mTORC1, is conditionally deleted in CSF1R-expressing macrophages (Tsc2csf1rΔ mice). In Tsc2csf1rΔ mice, common myeloid progenitors (CMPs), granulocyte-monocyte progenitors (GMPs), common monocyte progenitors / monocyte progenitors (cMoPs / MPs), inducible monocyte progenitors (iMoPs), and Ly6Cint CX3CR1low CD14- immature monocytes (iMOs), but not monocyte-dendritic cell progenitors (MDPs) and common dendritic cell progenitors (CDPs), accumulated and proliferated in the spleen. Consistent with this, monocytes, neutrophils, and neutrophil-like monocytes increased in the spleens of Tsc2csf1rΔ mice, whereas dendritic cells did not. The adoptive transfer of splenic iMOs into wild-type mice gave rise to granulomas in the liver and lungs. In these target organs, iMOs matured into Ly6Chi classical monocytes/macrophages (cMOs). Giant macrophages (gMAs) also accumulated in the liver and lungs, which were similar to granuloma macrophages in expression of cell surface markers such as MerTK and SLAMF7. Furthermore, the gMA-specific genes were expressed in human macrophages from sarcoidosis skin lesions. These results suggest that mTORC1 drives granuloma development by promoting the proliferation of monocyte/neutrophil progenitors and iMOs predominantly in the spleen, and that proliferating iMOs mature into cMOs and then gMAs to give rise to granuloma after migration into the liver and lungs in sarcoidosis.

Mint3-depletion-induced energy stress sensitizes triple-negative breast cancer to chemotherapy via HSF1 inactivation.

Given the lack of therapeutic targets, the conventional approach for managing triple-negative breast cancer (TNBC) involves the utilization of cytotoxic chemotherapeutic agents. However, most TNBCs acquire resistance to chemotherapy, thereby lowering the therapeutic outcome. In addition to oncogenic mutations in TNBC, microenvironment-induced mechanisms render chemoresistance more complex and robust in vivo. Here, we aimed to analyze whether depletion of Munc18-1 interacting protein 3 (Mint3), which activates hypoxia-inducible factor 1 (HIF-1) during normoxia, sensitizes TNBC to chemotherapy. We found that Mint3 promotes the chemoresistance of TNBC in vivo. Mint3 depletion did not affect the sensitivity of human TNBC cell lines to doxorubicin and paclitaxel in vitro but sensitized tumors of these cells to chemotherapy in vivo. Transcriptome analyses revealed that the Mint3-HIF-1 axis enhanced heat shock protein 70 (HSP70) expression in tumors of TNBC cells. Administering an HSP70 inhibitor enhanced the antitumor activity of doxorubicin in TNBC tumors, similar to Mint3 depletion. Mint3 expression was also correlated with HSP70 expression in human TNBC specimens. Mechanistically, Mint3 depletion induces glycolytic maladaptation to the tumor microenvironment in TNBC tumors, resulting in energy stress. This energy stress by Mint3 depletion inactivated heat shock factor 1 (HSF-1), the master regulator of HSP expression, via the AMP-activated protein kinase/mechanistic target of the rapamycin pathway following attenuated HSP70 expression. In conclusion, Mint3 is a unique regulator of TNBC chemoresistance in vivo via metabolic adaptation to the tumor microenvironment, and a combination of Mint3 inhibition and chemotherapy may be a good strategy for TNBC treatment.

Incorporation of human iPSC-derived stromal cells creates a pancreatic cancer organoid with heterogeneous cancer-associated fibroblasts.

The aggressiveness of pancreatic ductal adenocarcinoma (PDAC) is affected by the tumor microenvironment (TME). In this study, to recapitulate the PDAC TME ex vivo, we cocultured patient-derived PDAC cells with mesenchymal and vascular endothelial cells derived from human induced pluripotent stem cells (hiPSCs) to create a fused pancreatic cancer organoid (FPCO) in an air-liquid interface. FPCOs were further induced to resemble two distinct aspects of PDAC tissue. Quiescent FPCOs were drug resistant, likely because the TME consisted of abundant extracellular matrix proteins that were secreted from the various types of cancer-associated fibroblasts (CAFs) derived from hiPSCs. Proliferative FPCOs could re-proliferate after anticancer drug treatment, suggesting that this type of FPCO would be useful for studying PDAC recurrence. Thus, we generated PDAC organoids that recapitulate the heterogeneity of PDAC tissue and are a potential platform for screening anticancer drugs.

KMT2C expression and DNA homologous recombination repair factors in lung cancers with a high-grade fetal adenocarcinoma component.

Background: High-grade fetal adenocarcinoma of the lung (H-FLAC) is a rare variant of pulmonary adenocarcinoma. Our previous study showed a high frequency of KMT2C mutations in lung cancers with an H-FLAC component, showing that KMT2C dysfunction may be associated with the biological features of H-FLACs. Methods: In this study, we performed RNA sequencing and immunohistochemical analysis to identify the differentially expressed genes and corresponding pathways associated with H-FLACs, compared with common adenocarcinomas. Results: Ingenuity pathway analysis based on RNA sequencing data revealed that DNA homologous recombination repair (HRR) pathways were significantly inactivated in H-FLAC. Expression of KMT2C, ATM, ATR, and BRCA2 was significantly lower in H-FLACs than in common adenocarcinomas, and BRCA1 expression showed a decreasing trend. Pearson correlation analyses for all cases revealed that KMT2C expression showed a strong positive correlation (R>0.7) with the expression of ATR, BRCA1, and BRCA2 genes and a moderately positive correlation with ATM expression (R=0.47). Immunohistochemical analysis showed significantly lower levels of KMT2C, ATM, ATR, and BRCA2 expression in H-FLACs than in common adenocarcinomas, and a trend of lower BRCA1 levels. Additionally, KMT2C expression showed a weak to moderate correlation with that of ATM, ATR, BRCA1, and BRCA2. Conclusions: Cancers containing H-FLAC components showed lower levels of KMT2C and HRR factors than common lung adenocarcinomas, and their levels exhibited a positive correlation. These results support the hypothesis that loss of KMT2C function decreases the expression of the HRR factors in H-FLACs. H-FLACs with low KMT2C expression may be a good indication for poly (ADP-ribose) polymerase (PARP) inhibitor-based therapy.

Genetic analysis of low-grade adenosquamous carcinoma of the breast progressing to high-grade metaplastic carcinoma.

PURPOSE: Low-grade adenosquamous carcinoma (LGASC) is a rare type of metaplastic carcinoma of the breast (MBC) with an indolent clinical course. A few LGASC cases with high-grade transformation have been reported; however, the genetics underlying malignant progression of LGASC remain unclear. METHODS: We performed whole-genome sequencing analysis on five MBCs from four patients, including one case with matching primary LGASC and a lymph node metastatic tumor consisting of high-grade MBC with a predominant metaplastic squamous cell carcinoma component (MSC) that progressed from LGASC and three cases of independent de novo MSC. RESULTS: Unlike de novo MSC, LGASC and its associated MSC showed no TP53 mutation and tended to contain fewer structural variants than de novo MSC. Both LGASC and its associated MSC harbored the common GNAS c.C2530T:p.Arg844Cys mutation, which was more frequently detected in the cancer cell fraction of MSC. MSC associated with LGASC showed additional pathogenic deletions of multiple tumor-suppressor genes, such as KMT2D and BTG1. Copy number analysis revealed potential 18q loss of heterozygosity in both LGASC and associated MSC. The frequency of SMAD4::DCC fusion due to deletions increased with progression to MSC; however, chimeric proteins were not detected. SMAD4 protein expression was already decreased at the LGASC stage due to unknown mechanisms. CONCLUSION: Not only LGASC but also its associated high-grade MBC may be genetically different from de novo high-grade MBC. Progression from LGASC to high-grade MBC may involve the concentration of driver mutations caused by clonal selection and inactivation of tumor-suppressor genes.

LONRF2 is a protein quality control ubiquitin ligase whose deficiency causes late-onset neurological deficits.

Protein misfolding is a major factor of neurodegenerative diseases. Post-mitotic neurons are highly susceptible to protein aggregates that are not diluted by mitosis. Therefore, post-mitotic cells may have a specific protein quality control system. Here, we show that LONRF2 is a bona fide protein quality control ubiquitin ligase induced in post-mitotic senescent cells. Under unperturbed conditions, LONRF2 is predominantly expressed in neurons. LONRF2 binds and ubiquitylates abnormally structured TDP-43 and hnRNP M1 and artificially misfolded proteins. Lonrf2-/- mice exhibit age-dependent TDP-43-mediated motor neuron (MN) degeneration and cerebellar ataxia. Mouse induced pluripotent stem cell-derived MNs lacking LONRF2 showed reduced survival, shortening of neurites and accumulation of pTDP-43 and G3BP1 after long-term culture. The shortening of neurites in MNs from patients with amyotrophic lateral sclerosis is rescued by ectopic expression of LONRF2. Our findings reveal that LONRF2 is a protein quality control ligase whose loss may contribute to MN degeneration and motor deficits.

TLR7/8 stress response drives histiocytosis in SLC29A3 disorders.

Loss-of-function mutations in the lysosomal nucleoside transporter SLC29A3 cause lysosomal nucleoside storage and histiocytosis: phagocyte accumulation in multiple organs. However, little is known about the mechanism by which lysosomal nucleoside storage drives histiocytosis. Herein, histiocytosis in Slc29a3-/- mice was shown to depend on Toll-like receptor 7 (TLR7), which senses a combination of nucleosides and oligoribonucleotides (ORNs). TLR7 increased phagocyte numbers by driving the proliferation of Ly6Chi immature monocytes and their maturation into Ly6Clow phagocytes in Slc29a3-/- mice. Downstream of TLR7, FcRγ and DAP10 were required for monocyte proliferation. Histiocytosis is accompanied by inflammation in SLC29A3 disorders. However, TLR7 in nucleoside-laden splenic monocytes failed to activate inflammatory responses. Enhanced production of proinflammatory cytokines was observed only after stimulation with ssRNAs, which would increase lysosomal ORNs. Patient-derived monocytes harboring the G208R SLC29A3 mutation showed enhanced survival and proliferation in a TLR8-antagonist-sensitive manner. These results demonstrated that TLR7/8 responses to lysosomal nucleoside stress drive SLC29A3 disorders.

Polycomb repressive complex 1.1 coordinates homeostatic and emergency myelopoiesis.

Polycomb repressive complex (PRC) 1 regulates stem cell fate by mediating mono-ubiquitination of histone H2A at lysine 119. While canonical PRC1 is critical for hematopoietic stem and progenitor cell (HSPC) maintenance, the role of non-canonical PRC1 in hematopoiesis remains elusive. PRC1.1, a non-canonical PRC1, consists of PCGF1, RING1B, KDM2B, and BCOR. We recently showed that PRC1.1 insufficiency induced by the loss of PCGF1 or BCOR causes myeloid-biased hematopoiesis and promotes transformation of hematopoietic cells in mice. Here we show that PRC1.1 serves as an epigenetic switch that coordinates homeostatic and emergency hematopoiesis. PRC1.1 maintains balanced output of steady-state hematopoiesis by restricting C/EBPα-dependent precocious myeloid differentiation of HSPCs and the HOXA9- and ß-catenin-driven self-renewing network in myeloid progenitors. Upon regeneration, PRC1.1 is transiently inhibited to facilitate formation of granulocyte-macrophage progenitor (GMP) clusters, thereby promoting emergency myelopoiesis. Moreover, constitutive inactivation of PRC1.1 results in unchecked expansion of GMPs and eventual transformation. Collectively, our results define PRC1.1 as a novel critical regulator of emergency myelopoiesis, dysregulation of which leads to myeloid transformation.

UTX inactivation in germinal center B cells promotes the development of multiple myeloma with extramedullary disease.

UTX/KDM6A, a histone H3K27 demethylase and a key component of the COMPASS complex, is frequently lost or mutated in cancer; however, its tumor suppressor function remains largely uncharacterized in multiple myeloma (MM). Here, we show that the conditional deletion of the X-linked Utx in germinal center (GC) derived cells collaborates with the activating BrafV600E mutation and promotes induction of lethal GC/post-GC B cell malignancies with MM-like plasma cell neoplasms being the most frequent. Mice that developed MM-like neoplasms showed expansion of clonal plasma cells in the bone marrow and extramedullary organs, serum M proteins, and anemia. Add-back of either wild-type UTX or a series of mutants revealed that cIDR domain, that forms phase-separated liquid condensates, is largely responsible for the catalytic activity-independent tumor suppressor function of UTX in MM cells. Utx loss in concert with BrafV600E only slightly induced MM-like profiles of transcriptome, chromatin accessibility, and H3K27 acetylation, however, it allowed plasma cells to gradually undergo full transformation through activation of transcriptional networks specific to MM that induce high levels of Myc expression. Our results reveal a tumor suppressor function of UTX in MM and implicate its insufficiency in the transcriptional reprogramming of plasma cells in the pathogenesis of MM.

Histological markers, sickle-shaped blood vessels, myxoid area, and infiltrating growth pattern help stratify the prognosis of patients with myxofibrosarcoma/undifferentiated sarcoma.

Myxofibrosarcoma (MFS) and undifferentiated sarcoma (US) have been considered as tumors of the same lineage based on genetic/epigenetic profiling. Although MFS shows a notably better prognosis than US, there are no clear criteria for distinguishing between them. Here, we examined 85 patients with MFS/US and found that tumors with infiltrative growth patterns tended to have more myxoid areas and higher local recurrence rates but fewer distant metastases and better overall survival. Morphologically characteristic sickle-shaped blood vessels, which tended to have fewer αSMA-positive cells, were also observed in these tumors, compared with normal vessels. Based on the incidence of these sickle-shaped blood vessels, we subdivided conventionally diagnosed US into two groups. This stratification was significantly correlated with metastasis and prognosis. RNA sequencing of 24 tumors (9 MFS and 15 US tumors) demonstrated that the proteasome, NF-kB, and VEGF pathways were differentially regulated among these tumors. Expression levels of KDR and NFATC4, which encode a transcription factor responsible for the neuritin-insulin receptor angiogenic signaling, were elevated in the sickle-shaped blood vessel-rich US tumors. These findings indicate that further analyses may help elucidate the malignant potential of MFS/US tumors as well as the development of therapeutic strategies for such tumors.

Bromodomain protein BRD8 regulates cell cycle progression in colorectal cancer cells through a TIP60-independent regulation of the pre-RC complex.

Bromodomain-containing protein 8 (BRD8) is a subunit of the NuA4/TIP60-histone acetyltransferase complex. Although BRD8 has been considered to act as a co-activator of the complex, its biological role remains to be elucidated. Here, we uncovered that BRD8 accumulates in colorectal cancer cells through the inhibition of ubiquitin-dependent protein degradation by the interaction with MRG domain binding protein. Transcriptome analysis coupled with genome-wide mapping of BRD8-binding sites disclosed that BRD8 transactivates a set of genes independently of TIP60, and that BRD8 regulates the expression of multiple subunits of the pre-replicative complex in concert with the activator protein-1. Depletion of BRD8 induced cell-cycle arrest at the G1 phase and suppressed cell proliferation. We have also shown that the bromodomain of BRD8 is indispensable for not only the interaction with histone H4 or transcriptional regulation but also its own protein stability. These findings highlight the importance of bromodomain as a therapeutic target.

Identification of SARS-CoV-2 variants in wastewater using targeted amplicon sequencing during a low COVID-19 prevalence period in Japan.

Wastewater-based epidemiology is expected to be able to identify SARS-CoV-2 variants at an early stage via next-generation sequencing. In the present study, we developed a highly sensitive amplicon sequencing method targeting the spike gene of SARS-CoV-2, which allows for sequencing viral genomes from wastewater containing a low amount of virus. Primers were designed to amplify a relatively long region (599 bp) around the receptor-binding domain in the SARS-CoV-2 spike gene, which could distinguish initial major variants of concern. To validate the methodology, we retrospectively analyzed wastewater samples collected from a septic tank installed in a COVID-19 quarantine facility between October and December 2020. The relative abundance of D614G mutant in SARS-CoV-2 genomes in the facility wastewater increased from 47.5 % to 83.1 % during the study period. The N501Y mutant, which is the characteristic mutation of the Alpha-like strain, was detected from wastewater collected on December 24, 2020, which agreed with the fact that a patient infected with the Alpha-like strain was quarantined in the facility on this date. We then analyzed archived municipal wastewater samples collected between November 2020 and January 2021 that contained low SARS-CoV-2 concentrations ranging from 0.23 to 0.43 copies/qPCR reaction (corresponding to 3.30 to 4.15 log10 copies/L). The targeted amplicon sequencing revealed that the Alpha-like variant with D614G and N501Y mutations was present in municipal wastewater collected on December 4, 2020 and later, suggesting that the variant had already spread in the community before its first clinical confirmation in Japan on December 25, 2020. These results demonstrate that targeted amplicon sequencing of wastewater samples is a powerful surveillance tool applicable to low COVID-19 prevalence periods and may contribute to the early detection of emerging variants.

Visinin-like 1, a novel target gene of the Wnt/ß-catenin signaling pathway, is involved in apoptosis resistance in colorectal cancer.

BACKGROUND: Abnormal activation of Wnt/ß-catenin signaling is associated with various aspects of cancer development. This study explored the roles of novel target genes of the Wnt/ß-catenin signaling pathway in cancer cells. METHODS: Using the haploid chronic myelogenous leukemia cell line HAP1, RNA sequencing (RNA-seq) was performed to identify genes whose expression was increased by APC disruption and reversed by ß-catenin knockdown (KD). The regulatory mechanism and function of one of the candidate genes was investigated in colorectal cancer (CRC) cells. RESULTS: In total, 64 candidate genes whose expression was regulated by Wnt/ß-catenin signaling were identified. Of these candidate genes, the expression levels of six were reduced by ß-catenin KD in HCT116 CRC cells in our previous microarray. One of these genes was Visinin-like 1 (VSNL1), which belongs to the neuronal calcium-sensor gene family. The expression of VSNL1 was regulated by the ß-catenin/TCF7L2 complex via two TCF7L2-binding elements in intron 1. VSNL1 KD-induced apoptosis in VSNL1-positive CRC cells. Additionally, forced expression of wild-type VSNL1, but not a myristoylation, Ca2+ -binding, or dimerization-defective mutant, suppressed the apoptosis induced by camptothecin and doxorubicin in VSNL1-negative CRC cells. CONCLUSION: Our findings suggest that VSNL1, a novel target gene of the Wnt/ß-catenin signaling pathway, is associated with apoptosis resistance in CRC cells.