Biology subjects

Chayama, K.

Publications and source records attributed to Chayama, K..

14 recordsLinked to original sources

bioRxiv2026

Therapeutic Potential of the Novel Monoclonal Antibody 7-4G against HBsAg in a Mouse Model of Chronic Hepatitis B Virus Infection

Chronic hepatitis B virus (HBV) infection remains a major global health challenge because current antiviral therapies rarely achieve complete viral clearance. We evaluated the antiviral activity of a newly developed monoclonal antibody, 7-4G mAb, directed against the hepatitis B surface antigen (HBsAg). The antibody showed specific binding to the p27 component of HBsAg and efficiently removed HBV-related particles from patient serum in vitro. Significant HBV neutralizing activity of 7-4G mAb was observed in primary human hepatocytes and in humanized mouse models. In persistently HBV-infected PXB mice, a single administration of 7-4G mAb, either alone or in combination with another monoclonal antibody, reduced serum HBsAg levels and HBV DNA levels by two orders magnitude for two weeks after the treatment. In half of the treated mice, suppression of both viral markers was maintained through the study period, whereas rebound occurred within three to four weeks in the remaining animals. In addition, 7-4G mAb enhanced the HBV DNA-lowering effect of entecavir, a known anti-HBV drug. These findings support the further development of 7-4G mAb as part of an innovative HBV treatment strategy, addressing limitations of existing therapies and advancing toward a more effective HBV management solution.

immunology↗

bioRxiv2026

Identification of molecular determinants governing KIF4 cargo recognition of NTCP and their role in HBV/HDV infection

The surface availability of the sodium taurocholate co-transporting polypeptide (NTCP), which serves as entry receptor for Hepatitis B virus (HBV) and Hepatitis D virus (HDV), is a key determinant of HBV/HDV infectivity. We previously identified the Kinesin motor protein KIF4 as a key regulator of NTCP trafficking to the plasma membrane. However, the molecular mechanism by which NTCP is recognized as a KIF4 transport cargo has remained undefined. Here, we identified a leucine-rich motif, LLLI (aa 298-301), within the C-terminal transmembrane domain of NTCP as an essential determinant for KIF4 transport. Co-immunoprecipitation analyses revealed its importance for NTCP interaction with KIF4. This motif is conserved in another established KIF4 cargo, integrin {beta}1 (ITGB1), and mutation of the corresponding residues similarly disrupted ITGB1-KIF4 interaction, indicating a shared cargo recognition mechanism employed by KIF4. Functionally, disruption of the NTCP leucine-rich motif markedly impaired NTCP surface localization without affecting total protein expression, resulting in severe attenuation of HBV and HDV infection. Structural modeling and computational protein-protein interaction analysis indicated that the mutation does not alter NTCP structure or NTCP/preS1 binding affinity, supporting a trafficking-specific defect. Substitution mutations identified L298 and L299 as the minimal residues required for interaction with KIF4. Our findings define a recognition motif that regulates KIF4-dependent cargo identification and surface trafficking. It also underscores the potential of targeting KIF4-mediated NTCP recognition and transport to inhibit HBV and HDV entry. ImportanceHepatitis B and D viruses require the hepatocyte surface receptor NTCP for entry. We identified a conserved leucine-rich motif (LLLI, aa 298-301) in NTCP that is necessary for its recognition by the kinesin motor KIF4; disrupting this motif selectively impairs NTCP surface trafficking and markedly attenuates HBV/HDV infection without reducing total NTCP or intrinsic receptor function. Importantly, we identified a similar motif in integrin {beta}1 (ITGB1; aa 747-750) that is required for interaction with KIF4, revealing a similar cargo selection mechanism for different proteins. Scientifically, these findings define a motif-derived cargo-selection determinant implied by KIF4, advancing a general principle for kinesin-dependent cargo recognition. More broadly, this work highlights a possible host-directed antiviral approach that targets cargo-selection interfaces and provides a conceptual framework for manipulating kinesin-mediated trafficking of clinically relevant membrane proteins beyond NTCP, with implications for receptor regulation and membrane protein therapeutics.

microbiology↗

bioRxiv2025

RXR agonist S169 inhibits HBV/HDV entry in vitro by disrupting KIF4-dependent NTCP trafficking.

Chronic hepatitis B (HBV) and hepatitis D (HDV) viral infections pose serious global health challenges, and the lack of curative therapies calls for the development of new antiviral approaches. Recently, we have identified the Kinesin Family Member 4 (KIF4) as a crucial regulator of the surface transport for NTCP (HBV/HDV entry receptor). Our research has shown that the pan-RXR agonist, Bexarotene, suppresses KIF4 expression and inhibits HBV/HDV infections. However, the clinical use of Bexarotene is limited by poor physicochemical and pharmacokinetic (PK) properties and significant side effects. Here we investigated chemically diverse RXR modulators with tuned activity, and identified the RXR agonist S169 as a novel HBV/HDV entry inhibitor. S169 effectively blocks HBV and HDV infections in primary human hepatocyte (PXB) cultures without evident cytotoxicity. S169s suppressive effect on HBV infection was confirmed by reduction of secreted HBsAg and HBeAg, as well as inhibition of HBV cccDNA, pregenomic RNA, and intracellular HBV DNA. Mechanistically, S169 suppressed FOXM1-mediated KIF4 expression, leading to decreased NTCP surface levels and a marked decrease in HBV preS1 peptide binding to the hepatocyte cell surface. S169 is reported to exhibit enhanced oral bioavailability, favorable PK parameters, lower toxicity compared to Bexarotene. Interestingly, S169 induced a modest inhibition of NTCP-mediated bile acid transport up to 10 M, which remained unchanged at higher concentrations. Furthermore, S169 significantly impeded HBV spread in HBV infected long-time cultured PHHs (PXB). We speculate that S169 can be a promising seed for the development of novel oral HBV and HDV antiviral therapeutics.

microbiology↗

bioRxiv2025

Modeling of hepatitis B virus infection spread in primary human hepatocytes

Chronic hepatitis B virus (HBV) infection poses a significant global health threat, causing severe liver diseases including cirrhosis and hepatocellular carcinoma. We characterized HBV DNA kinetics in primary human hepatocytes (PHH) over 32 days post-inoculation (pi) and used agent-based modeling (ABM) to gain insights into HBV lifecycle and spread. Parallel PHH cultures were mock-treated or HBV entry inhibitor Myr-preS1 (6.25 g/mL) was initiated 24h pi. In untreated PHH, 3 viral DNA kinetic patterns were identified: (1) an initial decline, followed by (2) rapid amplification, and (3) slower amplification/accumulation. In the presence of Myr-preS1, viral DNA and infected cell numbers in phase 3 were effectively blocked, with minimal to no increase. This suggests that phase 2 represents viral amplification in initially infected cells, while phase 3 corresponds to viral spread to naive cells. The ABM reproduced well the HBV kinetic patterns observed and predicted that the viral eclipse phase lasts between 18 and 38 hours. After the eclipse phase, the viral production rate increases over time, starting with a slow production cycle of 1 virion per day, which gradually accelerates to 1 virion per hour after 3 days. Approximately 4 days later, virion production reaches a steady state production rate of 4 virions/hour. The estimated median efficacy of Myr-preS1 in blocking HBV spread was 91% (range: 90-92%). The HBV kinetics and the predicted estimates of the HBV eclipse phase duration and HBV production cycles in PHH are similar of those predicted in uPA/SCID mice with human livers. ImportanceWhile primary human hepatocytes (PHH) are the most physiologically relevant culture system for studying HBV infection in vitro, comprehensive understanding of HBV infection kinetics and spread in PHH is lacking. In this study, we characterize HBV viral kinetics and employ agent-based modeling (ABM) to provide quantitative insights into the HBV production cycle and viral spread in PHH. The ABM provides an estimate of HBV eclipse phase duration, HBV production cycles and Myr-preS1 efficacy in blocking HBV spread in PHH. The results resemble those predicted in uPA/SCID mice with human livers, demonstrating that estimated HBV infection kinetic parameters in PHH in vitro mirrors that observed in in vivo HBV infection chimeric mouse model.

systems biology↗

bioRxiv2022

Multiphasic hepatitis B virus kinetic patterns in humanized chimeric mice can be explained via stochastic agent-based modeling of intracellular virion production cycles

Serum hepatitis B virus (HBV) kinetics in urokinase-type plasminogen activator/severe combined immunodeficient (uPA-SCID) mice reconstituted with humanized livers from inoculation to steady state is highly dynamic despite the absence of an adaptive immune response. We developed a stochastic agent-based model that includes virion production cycles in individual infected human hepatocytes. The model was calibrated using a genetic algorithm approach with the serum HBV kinetics observed in mice inoculated with 108 HBV genome equivalents and fit the data well when the following viral production parameters were assumed: (1) An eclipse phase lasting 5-50 hours and (2) a post-eclipse phase production rate that is based on increasing production cycles initially starting with a long production cycle of 1 virion per 20 hours that gradually reaches 1 virion per hour after approximately 3-4 days before virion production increases dramatically to reach to a steady state production rate of 4 virions per hour per cell. The model was then validated by showing it could accurately simulate the viral kinetics observed with lower HBV inoculation doses (104-107 genome equivalents) in which similar, but delayed patterns were observed. Together, modeling suggests that it is the cyclic nature of the virus lifecycle combined with an initial slow but increasing rate of HBV production from each cell that plays a role in generating the observed multiphasic HBV kinetic patterns in humanized mice.

systems biology↗

bioRxiv2021

The kinesin KIF4 mediates HBV/HDV entry through regulation of surface NTCP localization and can be targeted by RXR agonists in vitro.

Intracellular transport via microtubule-based dynein and kinesin family motors plays a key role in viral reproduction and transmission. We show here that Kinesin Family Member 4 (KIF4) plays an important role in HBV/HDV infection. We intended to explore host factors impacting the HBV life cycle that can be therapeutically addressed using siRNA library transfection and HBV/NLuc (HBV/NL) reporter virus infection in HepG2-hNTCP C4 cells. KIF4 silencing resulted in a 3-fold reduction in luciferase activity following HBV/NL infection and suppressed both wild-type HBV and HDV infection. Transient KIF4 depletion reduced surface and raised intracellular NTCP (HBV/HDV entry receptor) levels, according to both cellular fractionation and immunofluorescence analysis (IF). Overexpression of wild-type KIF4 but not ATPase-null KIF4 regains the surface localization of NTCP in these cells. Furthermore, immunofluorescence (IF) revealed KIF4 and NTCP colocalization across microtubule filaments, and a co-immunoprecipitation study showed that KIF4 physically binds to NTCP. KIF4 expression is regulated by FOXM1. Interestingly, we discovered that RXR agonists (Bexarotene, and Alitretinoin) down-regulated KIF4 expression via FOXM1-mediated suppression, resulting in a substantial decrease in HBV-Pre-S1 protein attachment to HepG2-hNTCP cell surface and subsequent suppression of HBV infection in HepG2-hNTCP and primary human hepatocytes (PXB) (Bexarotene, IC50 1.89 {+/-} 0.98 M). Overall, our findings show that human KIF4 is a critical regulator of NTCP surface transport and localization, which is required for NTCP to function as a receptor for HBV/HDV entry. Furthermore, small molecules that suppress or alleviate KIF4 expression would be potential antiviral candidates that target HBV and HDV entry phases. Author SummaryUnderstanding HBV/HDV entry machinery and the mechanism by which NTCP (HBV/HDV entry receptor) surface expression is regulated is crucial to develop antiviral entry inhibitors. We found that NTCP surface transport is mainly controlled by the motor kinesin KIF4. Surprisingly, KIF4 was negatively regulated by RXR receptors through FOXM1-mediated suppression This study not only mechanistically correlated the role of RXR receptors in regulating HBV/HDV entry but also suggested a novel approach to develop therapeutic rexinoids for preventing HBV and/or HDV infections in important clinical situations, such as in patients undergoing liver transplantation or those who are at a high risk of HBV infection and unresponsive to HBV vaccination.

microbiology↗

bioRxiv2021

Comprehensive analysis of full-length transcripts reveal aberrations of splicing variants in liver cancer

Genes generate various transcripts by alternative splicing, and these transcripts can have diverse functions. However, in most transcriptome studies, short-reads sequencing technologies (next-generation sequencers) have been used and full-length transcripts have not been observed directly. Although long-reads sequencing technologies would enable us to sequence full-length transcripts, analysis of the data is a difficult task. In the present study, we developed an analysis pipeline named SPLICE to analyze full-length cDNA sequences. Using this method, we analyzed cDNA sequences from 42 pairs of hepatocellular carcinoma (HCC) and matched non-cancerous liver with Oxford Nanopore technology. Our analysis detected 46,663 transcripts from the protein-coding genes in the HCCs and the matched non-cancerous livers, of which 5,366 (11.5 %) were novel. Comparison of expression levels identified 9,933 differentially expressed transcripts (DETs) in 4,744 genes. Importantly, 746 genes with DET were not found by the gene-level analysis. We also identified novel exons derived from transposable elements (TEs). In the analysis of transcripts from hepatitis B virus (HBV), HBx-human TE fusions were found to be overexpressed in the HCCs. Furthermore, fusion gene detection showed novel recurrent fusion events. These results suggest that long-reads sequencing technologies allow us to analyze full-length transcripts, and show the importance of splicing variants in carcinogenesis.

cancer biology↗

bioRxiv2021

Aberrant integration of Hepatitis B virus DNA promotes major restructuring of human hepatocellular carcinoma genome architecture

Most cancers are characterized by the somatic acquisition of genomic rearrangements during tumour evolution that eventually drive the oncogenesis. There are different mutational mechanisms causing structural variation, some of which are specific to particular cancer types. Here, using multiplatform sequencing technologies, we identify and characterize a remarkable mutational mechanism in human hepatocellular carcinoma caused by Hepatitis B virus, by which DNA molecules from the virus are inserted into the tumour genome causing dramatic changes in its configuration, including non-homologous chromosomal fusions and megabase-size telomeric deletions. This aberrant mutational process, present in at least 8% of all HCC tumours, is active early during liver cancer evolution and can provide the driver rearrangements that a cancer clone requires to survive and grow.

cancer biology↗

bioRxiv2020

Understanding hepatitis B virus dynamics and the antiviral effect of interferon-alpha treatment in humanized chimeric mice

BackgroundWhereas the mode of action of lamivudine (LAM) against hepatitis B virus (HBV) is well established, the inhibition mechanism(s) of interferon- are less completely defined. To advance our understanding, we mathematically modelled HBV kinetics during pegylated interferon--2a (pegIFN), LAM and pegIFN+LAM treatment of chronically HBV-infected humanized uPA/SCID chimeric mice. MethodsThirty-nine uPA/SCID mice with humanized livers whose pre-treatment steady-state serum HBV reached 9.2{+/-}0.4 logIU/mL were treated with pegIFN, LAM or pegIFN+LAM for 14 days. Serum HBV DNA and intracellular HBV DNA were measured frequently. We developed a nonlinear mixed effect viral kinetic model and simultaneously fit it to the serum and intracellular HBV DNA data. ResultsUnexpectedly, even in the absence of an adaptive-immune response, a biphasic decline in serum HBV DNA and intracellular HBV DNA was observed in response to all treatments. Modeling predicts that the first phase represents pegIFN inhibiting intracellular HBV DNA synthesis with efficacy of 86%, which was similar under LAM and pegIFN+LAM. In contrast, there were distinct differences in HBV decline during the 2nd phase which was accounted for in the model by a time-dependent inhibition of intracellular HBV DNA synthesis with the steepest decline observed during pegIFN+LAM (0.46/d) and the slowest (0.052/d) during pegIFN mono-treatment. ConclusionsReminiscent of observations in patients treated with pegIFN and/or LAM, a biphasic HBV decline was observed in treated humanized mice in the absence of adaptive immune response. Interestingly, combination treatment does not increase the initial inhibition of HBV production; however, enhancement of second phase decline is observed providing insight into the dynamics of HBV treatment response and the mode of action of interferon- against HBV. Author SummaryChronic hepatitis B virus (HBV) infection remains a global health care problem as we lack sufficient curative treatment options. Elucidating the dynamic of HBV infection and treatment at the molecular level would potentially facilitate the development of novel, more effective HBV antivirals. Currently, the only well-established small animal HBV infection model available is the chimeric uPA/SCID mice with humanized livers; however, the HBV infection kinetics under interferon- (IFN) in this model system have not been determined in sufficient detail to support the in-depth studies of HBV treatment response needed to identify/confirm more effective drug targets. In this study 39 chronic HBV-infected uPA/SCID humanized mice treated with IFN and/or lamivudine were analysed using a mathematical modelling approach. We found that IFN main mode of action is blocking HBV DNA synthesis and that 73% of synthesized HBV DNA per are secreted from infected cells. Our data-driven mathematical modeling study provides novel insights into IFN anti-HBV mechanism(s) and viral-host interplay at the molecular level.

systems biology↗

bioRxiv2020

MafF is an anti-viral host factor that suppresses transcription from Hepatitis B Virus and Epstein Barr Virus promoters

Hepatitis B Virus (HBV) is a stealth virus that exhibits only minimal induction of the interferon system that is required for both innate and adaptive immune responses. However, 90% of acutely infected adults can clear the virus, suggesting the presence of additional mechanisms that facilitate viral clearance. Herein, we report that Maf bZIP transcription factor F (MafF) promotes host defense against infection with HBV. Using siRNA library and an HBV/NL reporter virus, we screened to identify anti-HBV host factors. Our data showed that silencing of MafF led to a 6-fold increase in luciferase activity after HBV/NL infection. Overexpression of MafF reduced HBV core promoter transcriptional activity, which was relieved upon mutating the putative MafF binding region. Loss of MafF expression by CRISPR/CAS9 (in HepG2-hNTCP-C4 cells) or siRNA silencing (in primary hepatocytes [PXB]), induced HBV core and HBV pregenomic RNA (pgRNA) levels, respectively, after HBV infection. MafF physically binds to HBV core promoter and competitively inhibits HNF-4 binding to an overlapping sequence in HBV enhancer II sequence (EnhII) as seen by ChIP analysis. MafF expression was induced by IL-1{beta}/TNF- treatment in both HepG2 and PXB cells, in an NF-{kappa}B-dependent manner. Consistently, MafF expression levels were significantly enhanced and positively correlated with the levels of these cytokines in patients with chronic HBV infection, especially in the immune clearance phase. ImportanceHBV is a leading cause of chronic liver diseases, infecting about 250 million people worldwide. HBV has developed strategies to escape interferon-dependent innate immune responses. Hence, the identification of other anti-HBV mechanisms is important for understanding HBV pathogenesis, and developing anti-HBV strategies. MafF was shown to suppress transcription from HBV core promoter, leading to a significant suppression of HBV life cycle. Furthermore, MafF expression was induced in chronic HBV patients and in primary human hepatocytes (PXB). This induction correlated with the levels of inflammatory cytokines (IL-1{beta} and TNF-). These data suggest that the induction of MafF contributes to the hosts antiviral defense by suppressing transcription from selected viral promoters. Our data shed light on a novel role for MafF as anti-HBV host restriction factor.

microbiology↗

bioRxiv2019

Large scale genome-wide association study in a Japanese population identified 45 novel susceptibility loci for 22 diseases

INTRODUCTORY PARAGRAPHThe overwhelming majority of participants in current genetic studies are of European ancestry1-3, limiting our genetic understanding of complex disease in non-European populations. To address this, we aimed to elucidate polygenic disease biology in the East Asian population by conducting a genome-wide association study (GWAS) with 212,453 Japanese individuals across 42 diseases. We detected 383 independent signals in 331 loci for 30 diseases, among which 45 loci were novel (P < 5 x 10-8). Compared with known variants, novel variants have lower frequency in European populations but comparable frequency in East Asian populations, suggesting the advantage of this study in discovering these novel variants. Three novel signals were in linkage disequilibrium (r2 > 0.6) with missense variants which are monomorphic in European populations (1000 Genomes Project) including rs11235604(p.R220W of ATG16L2, a autophagy-related gene) associated with coronary artery disease. We further investigated enrichment of heritability within 2,868 annotations of genome-wide transcription factor occupancy, andidentified 378 significant enrichments across nine diseases (FDR < 0.05) (e.g. NF-{kappa}B for immune-related diseases). This large-scale GWAS in a Japanese population provides insights into the etiology of common complex diseases and highlights the importance of performing GWAS in non-European populations.

genetics↗

bioRxiv2019

Serum miR-379 expression is related to the development and progression of hypercholesterolemia in non-alcoholic fatty liver disease

IntroductionNon-alcoholic fatty liver disease (NAFLD) has a wide spectrum, eventually leading to cirrhosis and hepatic carcinogenesis. We previously reported that a series of microRNAs (miRNAs) mapped in the 14q32.2 maternally imprinted gene region (Dlk1-Dio3 mat) are related to NAFLD development and progression in a mouse model. We examined the suitability of miR-379, a circulating Dlk1-Dio3 mat miRNA, as a human NAFLD biomarker.\n\nMethodsEighty NAFLD patients were recruited for this study. miR-379 was selected from the putative Dlk1-Dio3 mat miRNA cluster because it exhibited the greatest expression difference between NAFLD and non-alcoholic steatohepatitis in our preliminary study. Real-time PCR was used to examine the expression levels of miR-379 and miR-16 as an internal control.\n\nResultsCompared to normal controls, serum miR-379 expression was significantly up-regulated in NAFLD patients. Receiver operating characteristic curve analysis suggested that miR-379 is a suitable marker for discriminating NAFLD patients from controls, with an area under the curve value of 0.72. Serum miR-379 exhibited positive correlations with alkaline phosphatase, total cholesterol, and low-density-lipoprotein cholesterol levels in patients with early stage NAFLD (Brunt fibrosis stage 0 to 1). The correlation between serum miR-379 and cholesterol levels was lost in early stage NAFLD patients treated with statins. Software-based predictions indicated that various energy metabolism-related genes, including insulin-like growth factor-1 (IGF-1) and IGF-1 receptor, are potential targets of miR-379.\n\nConclusionsSerum miR-379 exhibits high potential as a biomarker for NAFLD. miR-379 appears to increase cholesterol lipotoxicity, leading to the development and progression of NAFLD, via interference with the expression of target genes, including those related to the IGF-1 signaling pathway. Our results could facilitate future research into the pathogenesis, diagnosis, and treatment of NAFLD.

molecular biology↗

bioRxiv2018

HBx enhances CPAP expression via interacting with CREB to promote hepatocarcinogenesis in HBV-associated HCC

Hepatitis B virus (HBV) encoded non-structure protein X (HBx) can promote cell proliferation, migration, and anti-apoptosis via activating several transcription factors and increasing their downstream gene expression in HBV-infected liver cells. Our previous report suggested that centrosomal P4.1-associated protein (CPAP) is required for HBx-mediated NF-{kappa}B activation. Here, we found that, upon HBV infection, overexpressed HBx can transcriptionally up-regulate CPAP via interacting with CREB. CPAP can directly interact with HBx to promote HBx-mediated cell proliferation and migration; and SUMO modification of CPAP is involved in interacting with HBx. Interestingly, CPAP can increase the HBx protein stability in an NF-{kappa}B-dependent manner; and overexpressed CPAP and HBx is positively correlated with the activation status of NF-{kappa}B in HCC. Increased expression of CREB and CPAP mRNAs exists in the high-risk group with a lower survival rate in hepatocellular carcinoma (HCC). These results suggest that the reciprocal regulation between CPAP and HBx may provide a microenvironment to facilitate HCC development via enhancing NF-{kappa}B activation, inflammatory cytokine production, and cancer maligancies. The findings of this study not only shed light on the role of CPAP in HBV-associated HCC, but also provide CPAP as a potential target for HBV-related HCC therapy.\n\nAuthor SummaryIn this study, we address a novel molecular mechanism for the collaboration between overexpressed HBx and CPAP in promoting hepatocarcinogenesis in HBV-associated HCC. Upon HBV infection, HBx is overexpressed and interacts with CREB to transcriptionally activate CPAP; the HBx/CPAP interaction promotes hepatocarcinogenesis. Clinical analysis found that co-overexpressed CPAP and CREB exist in the high-risk group with a lower survival rate in HCC. Additionally, overexpressed CPAP contributes to HBx protein stability in a NF-{kappa}B-dependent pathway. Our study provides a potential translational application in targeting CREB-CPAP axis in HBV-associated HCC.

cancer biology↗

bioRxiv2017

In-depth characterization of the cisplatin mutational signature in a human cell line and in esophageal and liver tumors

Background and aimsCisplatin reacts with DNA, and thereby likely generates a characteristic pattern of somatic mutations, called a mutational signature. Despite widespread use of cisplatin in cancer treatment and its role in contributing to secondary malignancies, its mutational signature has not been delineated. We hypothesize that cisplatins mutational signature can serve as a biomarker to identify cisplatin mutagenesis in suspected secondary malignancies. Knowledge of which tissues are at risk of developing cisplatin-induced secondary malignancies could lead to guidelines for non-invasive monitoring for secondary malignancies after cisplatin chemotherapy.\n\nMethodsWe performed whole genome sequencing of 10 independent clones of cisplatin-exposed MCF-10A and HepG2 cells, and delineated the patterns of single- and dinucleotide mutations in terms of flanking sequence, transcription strand bias, and other characteristics. We used the mSigAct signature presence test and non-negative matrix factorization to search for cisplatin mutagenesis in hepatocellular carcinomas and esophageal adenocarcinomas.\n\nResultsAll clones showed highly consistent patterns of single- and dinucleotide substitutions. The proportion of dinucleotide substitutions was high: 8.1% of single nucleotide substitutions were part of dinucleotide substitutions, presumably due to cisplatins propensity to form intra-and inter-strand crosslinks between purine bases in DNA. We identified likely cisplatin exposure in 9 hepatocellular carcinomas and 3 esophageal adenocarcinomas. All hepatocellular carcinomas for which clinical data were available and all esophageal cancers indeed had histories of cisplatin treatment.\n\nConclusionsWe experimentally delineated the single- and dinucleotide mutational signature of cisplatin. This signature enabled us to detect previous cisplatin exposure in human hepatocellular carcinomas and esophageal adenocarcinomas with high confidence.

cancer biology↗