A novel support vector machine-based 1-day, single-dose prediction model of genotoxic hepatocarcinogenicity in rats

The development of a rapid and accurate model for determining the genotoxicity and carcinogenicity of chemicals is crucial for effective cancer risk assessment. This study aims to develop a 1-day, single-dose model for identifying genotoxic hepatocarcinogens (GHCs) in rats. Microarray gene expression data from the livers of rats administered a single dose of 58 compounds, including 5 GHCs, was obtained from the Open TG-GATEs database and used for the identification of marker genes and the construction of a predictive classifier to identify GHCs in rats. We identified 10 gene markers commonly responsive to all 5 GHCs and used them to construct a support vector machine-based predictive classifier. In the silico validation using the expression data of the Open TG-GATEs database indicates that this classifier distinguishes GHCs from other compounds with high accuracy. To further assess the model's effectiveness and reliability, we conducted multi-institutional 1-day single oral administration studies on rats. These studies examined 64 compounds, including 23 GHCs, with gene expression data of the marker genes obtained via quantitative PCR 24 h after a single oral administration. Our results demonstrate that qPCR analysis is an effective alternative to microarray analysis. The GHC predictive model showed high accuracy and reliability, achieving a sensitivity of 91% (21/23) and a specificity of 93% (38/41) across multiple validation studies in three institutions. In conclusion, the present 1-day single oral administration model proves to be a reliable and highly sensitive tool for identifying GHCs and is anticipated to be a valuable tool in identifying and screening potential GHCs.

Stromal area differences with epithelial-mesenchymal transition gene changes in conjunctival and orbital mucosa-associated lymphoid tissue lymphoma

Purpose

To examine the molecular biological differences between conjunctival mucosa-associated lymphoid tissue (MALT) lymphoma and orbital MALT lymphoma in ocular adnexa lymphoma.

Methods

Observational case series. A total of 129 consecutive, randomized cases of ocular adnexa MALT lymphoma diagnosed histopathologically between 2008 and 2020.Total RNA was extracted from formalin-fixed paraffin-embedded tissue from ocular adnexa MALT lymphoma, and RNA-sequencing was performed. Orbital MALT lymphoma gene expression was compared with that of conjunctival MALT lymphoma. Gene set (GS) analysis detecting for gene set cluster was performed in RNA-sequence. Related proteins were further examined by immunohistochemical staining. In addition, artificial segmentation image used to count stromal area in HE images.

Results

GS analysis showed differences in expression in 29 GS types in primary orbital MALT lymphoma (N=5,5, FDR q-value <0.25). The GS with the greatest difference in expression was the GS of epithelial-mesenchymal transition (EMT). Based on this GS change, immunohistochemical staining was added using E-cadherin as an epithelial marker and vimentin as a mesenchymal marker for EMT. There was significant staining of vimentin in orbital lymphoma (P<0.01, N=129) and of E-cadherin in conjunctival lesions (P=0.023, N=129). Vimentin staining correlated with Ann Arbor staging (1 versus >1) independent of age and sex on multivariate analysis (P=0.004). Stroma area in tumor were significant difference(P<0.01).

Conclusion

GS changes including EMT and stromal area in tumor were used to demonstrate the molecular biological differences between conjunctival MALT lymphoma and orbital MALT lymphoma in ocular adnexa lymphomas.

Evaluation of the Mechanisms Involved in the Development of Bladder Toxicity following Exposure to Occupational Bladder Cancer Causative Chemicals Using DNA Adductome Analysis

Occupational exposure to aromatic amines (AAs) is an important risk factor for urinary bladder cancer. This study aimed to evaluate the toxicity of AAs and analyze the carcinogenic mechanisms in rat bladder by comprehensive analysis of DNA adducts (DNA adductome). DNA was extracted from the bladder epithelia of rats treated with AAs, including acetoacet-o-toluidine (AAOT) and o-toluidine (OTD), and adductome analysis was performed. Principal component analysis-discriminant analysis revealed that OTD and AAOT observed in urinary bladder hyperplasia could be clearly separated from the controls and other AAs. After confirming the intensity of each adduct, four adducts were screened as having characteristics of the OTD/AAOT treatment. Comparing with the in-house DNA adduct database, three of four candidates were identified as oxidative DNA adducts, including 8-OH-dG, based on mass fragmentation together with high-resolution accurate mass (HRAM) spectrometry data. Therefore, findings suggested that oxidative stress may be involved in the toxicity of rat bladder epithelium exposed to AAs. Consequently, the administration of apocynin, an inhibitor of nicotinamide adenine dinucleotide phosphate oxidase, in six-week-old rats fed with 0.6% OTD in their diet resulted in simple hyperplastic lesions in the bladder that were suppressed by apocynin. The labeling indices of Ki67, γ-H2AX, and 8-OHdG were significantly decreased in an apocynin concentration-dependent manner. These findings indicate that oxidative stress may have contributed to the development of urinary cancer induced by OTD.

DNA Methylation Aberrations in Dimethylarsinic Acid-Induced Bladder Carcinogenesis

Arsenic is a known human urinary bladder carcinogen. While arsenic is known to cause aberrant DNA methylation, the mechanism of arsenic-triggered bladder carcinogenesis is not fully understood. The goal of this study was to identify aberrant DNA methylation in rat bladder urothelial carcinoma (UC) induced by dimethylarsinic acid (DMAV), a major organic metabolite of arsenic. We performed genome-wide DNA methylation and microarray gene expression analyses of DMAV-induced rat UCs and the urothelium of rats treated for 4 weeks with DMAV. We identified 40 genes that were both hypermethylated and downregulated in DMAV-induced rat UCs. Notably, four genes (CPXM1, OPCML, TBX20, and KCND3) also showed reduced expression in the bladder urothelium after 4 weeks of exposure to DMAV. We also found that CPXM1 is aberrantly methylated and downregulated in human bladder cancers and human bladder cancer cells. Genes with aberrant DNA methylation and downregulated expression in DMAV-exposed bladder urothelium and in DMAV-induced UCs in rats, suggest that these alterations occurred in the early stages of arsenic-induced bladder carcinogenesis. Further study to evaluate the functions of these genes will advance our understanding of the role of aberrant DNA methylation in arsenic bladder carcinogenesis, and will also facilitate the identification of new therapeutic targets for arsenic-related bladder cancers.

Early detection of genotoxic hepatocarcinogens in rats using γH2AX and Ki-67: prediction by machine learning

Direct DNA double-strand breaks result in phosphorylation of H2AX, a variant of the histone H2 protein. Phosphorylated H2AX (γH2AX) may be a potential indicator in the evaluation of genotoxicity and hepatocarcinogenicity. In this study, γH2AX and Ki-67 were detected in the short-term responses (24 h after chemical administration) to classify genotoxic hepatocarcinogens (GHs) from non-GH chemicals. One hundred and thirty-five 6-week-old Crl: CD(SD) (SPF) male rats were treated with 22 chemicals including 11 GH and 11 non-GH, sacrificed 24 h later, and immunostained with γH2AX and Ki-67. Positivity rates of these markers were measured in the 3 liver ZONEs 1-3; portal, lobular, and central venous regions. These values were input into 3 machine learning models-Naïve Bayes, Random Forest, and k-Nearest Neighbor to classify GH and non-GH using a 10-fold cross-validation method. All 11 and 10 out of 11 GH caused significant increase in γH2AX and Ki-67 levels, respectively (P < .05). Of the 3 machine learning models, Random Forest performed the best. GH were identified with 95.0% sensitivity (76/80 GH-treated rats), 90.9% specificity (50/55 non-GH-treated rats), and 90.0% overall correct response rate using γH2AX staining, and 96.2% sensitivity (77/80), 81.8% specificity (45/55), and 90.4% overall correct response rate using Ki-67 labeling. Random Forest model using γH2AX and Ki-67 could independently predict GH in the early stage with high accuracy.

Recent Insights into the Biomarkers, Molecular Targets and Mechanisms of Non-Alcoholic Steatohepatitis-Driven Hepatocarcinogenesis

Non-alcoholic fatty liver disease (NAFLD) or metabolic dysfunction-associated steatotic liver disease (MASLD) and steatohepatitis (NASH) are chronic hepatic conditions leading to hepatocellular carcinoma (HCC) development. According to the recent "multiple-parallel-hits hypothesis", NASH could be caused by abnormal metabolism, accumulation of lipids, mitochondrial dysfunction, and oxidative and endoplasmic reticulum stresses and is found in obese and non-obese patients. Recent translational research studies have discovered new proteins and signaling pathways that are involved not only in the development of NAFLD but also in its progression to NASH, cirrhosis, and HCC. Nevertheless, the mechanisms of HCC developing from precancerous lesions have not yet been fully elucidated. Now, it is of particular importance to start research focusing on the discovery of novel molecular pathways that mediate alterations in glucose and lipid metabolism, which leads to the development of liver steatosis. The role of mTOR signaling in NASH progression to HCC has recently attracted attention. The goals of this review are (1) to highlight recent research on novel genetic and protein contributions to NAFLD/NASH; (2) to investigate how recent scientific findings might outline the process that causes NASH-associated HCC; and (3) to explore the reliable biomarkers/targets of NAFLD/NASH-associated hepatocarcinogenesis.

Dimethylarsinic acid induces bladder carcinogenesis via the amphiregulin pathway

Dimethylarsinic acid (DMA) is a major metabolite in the urine of humans and rats exposed to inorganic arsenicals, and is reported to induce rat bladder carcinogenesis. In the present study, we focused on early pathways of carcinogenesis triggered by DMA that were also active in tumors. RNA expression in the bladder urothelium of rats treated with 0 and 200 ppm DMA in the drinking water for 4 weeks and in bladder tumors of rats treated with 200 ppm DMA for 2 years was initially examined using microarray analysis and Ingenuity Pathway Analysis (IPA). Expression of 160 genes was altered in both the urothelium of rats treated for 4 weeks with DMA and in DMA-induced tumors. IPA associated 36 of these genes with liver tumor diseases. IPA identified the amphiregulin (Areg)-regulated pathway as a Top Regulator Effects Network. Therefore, we focused on Areg and 6 of its target genes: cyclin A2, centromere protein F, marker of proliferation Ki-67, protein regulator of cytokinesis 1, ribonucleotide reductase M2, and topoisomerase II alpha. We confirmed high mRNA expression of Areg and its 6 target genes in both the urothelium of rats treated for 4 weeks with DMA and in DMA-induced tumors. RNA interference of human amphiregulin (AREG) expression in human urinary bladder cell lines T24 and UMUC3 decreased expression of AREG and its 6 target genes and decreased cell proliferation. These data suggest that Areg has an important role in DMA-induced rat bladder carcinogenesis.

Irradiation plus myeloid-derived suppressor cell-targeted therapy for overcoming treatment resistance in immunologically cold urothelial carcinoma

BACKGROUND

Radiotherapy (RT) has recently been highlighted as a partner of immune checkpoint inhibitors. The advantages of RT include activation of lymphocytes while it potentially recruits immunosuppressive cells, such as myeloid-derived suppressor cells (MDSCs). This study aimed to investigate the mechanism of overcoming treatment resistance in immunologically cold tumours by combining RT and MDSC-targeted therapy.

METHODS

The abscopal effects of irradiation were evaluated using MB49 and cisplatin-resistant MB49R mouse bladder cancer cells, with a focus on the frequency of immune cells and programmed cell death-ligand 1 (PD-L1) expression in a xenograft model.

RESULTS

MB49R was immunologically cold compared to parental MB49 as indicated by the fewer CD8+ T cells and lower PD-L1 expression. Polymorphonuclear MDSCs increased in both MB49 and MB49R abscopal tumours, whereas the infiltration of CD8+ T cells increased only in MB49 but not in MB49R tumours. Interestingly, PD-L1 expression was not elevated in abscopal tumours. Finally, blocking MDSC in combination with RT remarkably reduced the growth of both MB49 and MB49R abscopal tumours regardless of the changes in the frequency of infiltrating CD8+ T cells.

CONCLUSIONS

The combination of RT and MDSC-targeted therapy could overcome treatment resistance in immunologically cold tumours.

o-Toluidine metabolism and effects in the urinary bladder of humanized-liver mice

Occupational exposure to aromatic amines is one of the most important risk factors for urinary bladder cancer. When considering the carcinogenesis of aromatic amines, metabolism of aromatic amines in the liver is an important factor. In the present study, we administered ortho-toluidine (OTD) in the diet to mice for 4 weeks. We used NOG-TKm30 mice (control) and humanized-liver mice, established via human hepatocyte transplantation, to compare differences in OTD-induced expression of metabolic enzymes in human and mouse liver cells. We also investigated OTD-urinary metabolites and proliferative effects on the urinary bladder epithelium. RNA and immunohistochemical analyses revealed that expression of N-acetyltransferases mRNA in the liver tended to be lower than that of the P450 enzymes, and that OTD administration had little effect on N-acetyltransferase mRNA expression levels. However, expression of CYP3A4 was increased in the livers of humanized-liver mice, and expression of Cyp2c29 (human CYP2C9/19) was increased in the livers of NOG-TKm30 mice. OTD metabolites in the urine and cell proliferation activities in the bladder urothelium of NOG-TKm30 and humanized-liver mice were similar. However, the concentration of OTD in the urine of NOG-TKm30 mice was markedly higher than in the urine of humanized-liver mice. These data demonstrate differences in hepatic metabolic enzyme expression induced by OTD in human and mouse liver cells, and consequent differences in the metabolism of OTD by human and mouse liver cells. This type of difference could have a profound impact on the carcinogenicity of compounds that are metabolized by the liver, and consequently, would be important in the extrapolation of data from animals to humans.

Deficiency of CHAMP1, a gene related to intellectual disability, causes impaired neuronal development and a mild behavioural phenotype

CHAMP1 is a gene associated with intellectual disability, which was originally identified as being involved in the maintenance of kinetochore–microtubule attachment. To explore the neuronal defects caused by CHAMP1 deficiency, we established mice that lack CHAMP1. Mice that are homozygous knockout for CHAMP1 were slightly smaller than wild-type mice and died soon after birth on pure C57BL/6J background. Although gross anatomical defects were not found in CHAMP1^−/− mouse brains, mitotic cells were increased in the cerebral cortex. Neuronal differentiation was delayed in CHAMP1^−/− neural stem cells in vitro, which was also suggested in vivo by CHAMP1 knockdown. In a behavioural test battery, adult CHAMP1 heterozygous knockout mice showed mild memory defects, altered social interaction, and depression-like behaviours. In transcriptomic analysis, genes related to neurotransmitter transport and neurodevelopmental disorder were downregulated in embryonic CHAMP1^−/− brains. These results suggest that CHAMP1 plays a role in neuronal development, and CHAMP1-deficient mice resemble some aspects of individuals with CHAMP1 mutations.

OTUD1 deubiquitinase regulates NF-κB- and KEAP1-mediated inflammatory responses and reactive oxygen species-associated cell death pathways

Deubiquitinating enzymes (DUBs) regulate numerous cellular functions by removing ubiquitin modifications. We examined the effects of 88 human DUBs on linear ubiquitin chain assembly complex (LUBAC)-induced NF-κB activation, and identified OTUD1 as a potent suppressor. OTUD1 regulates the canonical NF-κB pathway by hydrolyzing K63-linked ubiquitin chains from NF-κB signaling factors, including LUBAC. OTUD1 negatively regulates the canonical NF-κB activation, apoptosis, and necroptosis, whereas OTUD1 upregulates the interferon (IFN) antiviral pathway. Mass spectrometric analysis showed that OTUD1 binds KEAP1, and the N-terminal intrinsically disordered region of OTUD1, which contains an ETGE motif, is indispensable for the KEAP1-binding. Indeed, OTUD1 is involved in the KEAP1-mediated antioxidant response and reactive oxygen species (ROS)-induced cell death, oxeiptosis. In Otud1^-/--mice, inflammation, oxidative damage, and cell death were enhanced in inflammatory bowel disease, acute hepatitis, and sepsis models. Thus, OTUD1 is a crucial regulator for the inflammatory, innate immune, and oxidative stress responses and ROS-associated cell death pathways.

Clinical relevance of tertiary lymphoid structures in esophageal squamous cell carcinoma

BACKGROUND

Tertiary lymphoid structures (TLSs) have been reported to be involved in immune responses in many carcinomas. This study investigated the significance of TLSs in esophageal squamous cell carcinoma, focusing on TLS maturation.  METHODS: The relationships of TLSs with clinicopathological features of 236 patients who underwent curative surgery for stage 0-IV esophageal squamous cell carcinoma were investigated. Mature TLSs, in which the germinal center formation was rich in CD23⁺ cells, were classified as TLSs containing a germinal center (GC-TLSs). GC-TLS densities were measured, and CD8⁺ cells were counted. The prognostic impact of GC-TLSs was assessed by Kaplan-Meier plots using the log-rank test for the relapse-free survival. A comparative study of GC-TLSs was performed using the Wilcoxon rank sum test. The relationship between GC-TLSs and CD8⁺ cells was examined by Spearman's rank correlation coefficient test.

RESULTS

TLSs were located mainly at the invasive margin of the tumor in cases with esophageal squamous cell carcinoma. Among the patients treated with neoadjuvant chemotherapy, those with advanced disease had a better prognosis in the GC-TLS high-density group than did those in the GC-TLS low-density group. Patients in whom neoadjuvant chemotherapy was effective had more GC-TLSs than those in whom it was less effective. The density of GC-TLSs and the number of tumor-infiltrating CD8⁺ cells were higher in patients treated with neoadjuvant chemotherapy than in those without chemotherapy, and a weak correlation between the density of GC-TLSs and the number of tumor-infiltrating CD8⁺ cells was observed. Moreover, co-culturing of PBMCs with an anticancer drug-treated esophageal squamous cell carcinoma cell line increased the CD20 and CD23 expression in PBMCs in vitro.

CONCLUSION

TLS maturation may be important for evaluating the local tumor immune response in patients treated with neoadjuvant chemotherapy for esophageal squamous cell carcinoma. The present results suggest that TLS maturation may be a useful target for predicting the efficacy of immunotherapy, including immune checkpoint inhibitor treatment for esophageal squamous cell carcinoma.

The carbonic anhydrase inhibitor acetazolamide inhibits urinary bladder cancers via suppression of β-catenin signaling

Carbonic anhydrases (CAs) play an important role in maintaining pH homeostasis. We previously demonstrated that overexpression of CA2 was associated with invasion and progression of urothelial carcinoma (UC) in humans. The purpose of the present study was to evaluate the effects of the CA inhibitor acetazolamide (Ace) on N‐butyl‐N‐(4‐hydroxybutyl)nitrosamine (BBN)‐induced bladder carcinogenesis in mice and explore the function of CA2 in muscle invasion by UC. Male mice were treated with 0.025% (experiment 1) or 0.05% BBN (experiment 2) in their drinking water for 10 weeks, then treated with cisplatin (Cis), Ace, or Cis plus Ace for 12 weeks. In experiment 1, the overall incidence of BBN‐induced UCs was significantly decreased in the BBN→Ace and BBN→Cis+Ace groups. In experiment 2, the overall incidence of BBN‐induced UCs was significantly decreased in the BBN→Cis+Ace group, and the incidence of muscle invasive UC was significantly decreased in both the BBN→Ace and the BBN→Cis+Ace groups. We also show that overexpression of CA2 by human UC cells T24 and UMUC3 significantly increased their migration and invasion capabilities, and that Ace significantly inhibited migration and invasion by CA2‐overexpressing T24 and UMUC3 cells. These data demonstrate a functional association of CA2 with UC development and progression, confirming the association of CA2 with UC that we had shown previously by immunohistochemical analysis of human UC specimens and proteome analysis of BBN‐induced UC in rats. Our finding that inhibition of CA2 inhibits UC development and muscle invasion also directly confirms that CA2 is a potential therapeutic target for bladder cancers.

FOXP3 and CXCR4-positive regulatory T cells in the tumor stroma as indicators of tumor immunity in the conjunctival squamous cell carcinoma microenvironment

Conjunctival squamous cell carcinoma (SCC) is the most common ocular surface neoplasia. The purpose of this retrospective study was to examine the role of regulatory T cell (Treg) activity in tumor immunity and investigate the tumor microenvironment as a new treatment focus in conjunctival SCC. Cancer progression gene array and immunohistochemical analyses of FOXP3 as a Treg marker, CD8 as a tumor-infiltrating lymphocyte marker, and CXCR4 expression on activated Tregs were conducted in a series of 31 conjunctival SCC cases. The objective was to investigate the immunoreactive response in tumor cells and stromal cells in the cancer microenvironment. The stroma ratio in tumor cells was investigated by monitoring α-smooth muscle actine (SMA) expression between carcinoma in situ (Tis) and advanced carcinoma (Tadv) (P<0.01). No significant change in PD-L1 expression was observed in this study (P = 0.15). Staining patterns of FOXP3, CD8, and CXCR4 were examined separately between tumor cells and stromal cells in SCC tumors. Differences in staining of FOXP3 in Tregs and CD8 in tumor-infiltrating lymphocytes in tumor stroma in the Tis group were observed compared with the Tadv group (each P<0.01). In addition, double immunostaining of CXCR4/FOXP3 was correlated with progression-free survival (P = 0.049). Double immunostaining of CXCR4/FOXP3 correlated with American Joint Committee on Cancer T-stage, independent of age or Ki67 index (P<0.01). Our results show that FOXP3 and the CXCR4/FOXP3 axis are important pathologic and prognostic factors of ocular surface neoplasia, including SCC. The tumor microenvironment of conjunctival SCC should be considered in the future development of treatment options.

Response biomarkers of inhalation exposure to cigarette smoke in the mouse lung

Cigarette smoking is known to increase the risk of cancer and chronic obstructive pulmonary disease (COPD). In this study, we evaluated the effects of short-term nose-only inhalation exposure to cigarette smoke in mice. Male 10-week-old C57BL mice were exposed to clean air (control) or mainstream cigarette smoke for 1 h/day, 5 days/week, for 2 or 4 weeks. Exposure to cigarette smoke increased the number of inflammatory cells, especially neutrophils, in the bronchoalveolar lavage fluid, increased inflammatory cell infiltration foci, and caused an increase in the thickness of the peripheral bronchial epithelium. Microarray gene expression analysis indicated that smoke exposure induced inflammatory responses, including leukocyte migration and activation of phagocytes and myeloid cells, as early as two weeks after the initiation of exposure. Importantly, chemokine (C-C motif) ligand 17, resistin-like alpha, and lipocalin 2 were upregulated and may serve as useful markers of the toxic effects of exposure to cigarette smoke before pulmonary histological changes become evident.

Expression of thrombospondin-1 in conjunctival squamous cell carcinoma is correlated to the Ki67 index and associated with progression-free survival

PURPOSE

Conjunctival squamous cell carcinoma (SCC) is primarily treated with surgical resection. SCC has various stages, and local recurrence is common. The purpose of this study was to investigate thrombospondin-1 expression and its association with prognosis.

METHODS

In this retrospective study, a gene expression array along with immunohistochemistry were performed for the evaluation of thrombospondin-1 expression, localization, as well as Ki67 labeling cell indices in carcinoma in situ (Tis) and advanced conjunctival SCC (Tadv). The presence or absence and intensity of cytoplasmic and nuclear staining in tumor cells were also divided into groups with a score of 0-3 and semi-quantitatively analyzed to investigate intracellular staining patterns. The association between thrombospondin-1 expression and tumor progression in a series of 31 conjunctival SCCs was further investigated.

RESULTS

All 31 patients in the cohort (100%) were East Asian. A simple comparison between Tis and Tadv demonstrated significant differences in expressions of 45 genes, including thrombospondin-1 (p < 0.01). In this cohort, 30/31 tumors were positive (96%) for thrombospondin-1. Furthermore, thrombospondin-1 intracellular staining pattern analysis scores were 2.12 and 0.96 for nuclear and cytoplasmic staining, respectively, with a significant difference observed between Tis and Tadv (p < 0.01). Alteration of the Ki67 labeling index was significantly correlated with that of the thrombospondin-1 cytoplasmic score (p = 0.030). Furthermore, univariate Cox regression analysis showed a significant correlation between thrombospondin-1 staining and progression-free survival (p = 0.026) and final orbital exenteration (p = 0.019).

CONCLUSIONS

The present results demonstrated that thrombospondin-1 is a potential molecular target in the pathology of conjunctival SCC, in addition to serving as a prognostic factor.

ER membrane protein complex 1 interacts with STIM1 and regulates store-operated Ca2+ entry

Store-operated calcium entry (SOCE) is the process by which the emptying of endoplasmic reticulum (ER) Ca2+ stores causes an influx of Ca2+ across the plasma membrane. It is the major Ca2+ influx pathway in non-excitable cells and has a wide array of physiological functions. Upon store depletion, stromal interaction molecule 1 (STIM1), an ER calcium sensor relocates into discrete puncta at the ER-plasma membrane junction region, which results in the coupling of Ca2+ channels to initiate SOCE. However, the mechanism regulating STIM1 activity remains poorly understood. Here, we performed affinity purification of STIM1 and uncovered ER membrane protein complex 1 (EMC1) as a STIM1 binding partner. We showed that this interaction occurred in the ER through the intraluminal region of STIM1. After store depletion, EMC1 does not cluster adjacent to the plasma membrane, which suggests that it is distributed differently from STIM1. EMC1 knockdown with small interfering RNA resulted in a marked decrease in SOCE. Thus, these findings suggest that EMC1 functions as a positive regulator of SOCE.

Tertiary lymphoid structures show infiltration of effective tumor-resident T cells in gastric cancer

Several studies have reported that tissue‐resident memory T cells (TRM cells) or tertiary lymphoid structures (TLSs) are associated with a good prognosis. The aim of this study was to clarify the association of TRM cells and TLSs in the tumor immune microenvironment in gastric cancer (GC). We performed immunohistochemical and immunofluorescence staining to detect the presence of CD103⁺ T cells and to assess the association between CD103⁺ T cells and TLSs. CD103⁺ T cells were observed in the tumor epithelium accompanied by CD8⁺ T cells and were associated with a better prognosis in GC. Furthermore, CD103⁺ T cells were located around TLSs, and patients with CD103^high had more rich TLSs. Patients who had both CD103^high cells and who were TLS‐rich had a better prognosis than patients with CD103^low cells and who were TLS‐poor. Moreover, for patients who received PD‐1 blockade therapy, CD103^high and TLS‐rich predicted a good response. Flow cytometry was performed to confirm the characteristics of CD103⁺CD8⁺ T cells and showed that CD103⁺CD8⁺ T cells in GC expressed higher levels of PD‐1, granzyme B, and interferon‐γ than CD103⁻CD8⁺ T cells. Our results suggested that CD103⁺CD8⁺ cells in GC are correlated with TLSs, resulting in enhanced antitumor immunity in GC.

Cache Domain Containing 1 Is a Novel Marker of Non-Alcoholic Steatohepatitis-Associated Hepatocarcinogenesis

Simple Summary

The aim of the present study was to discover novel early molecular biomarkers of liver neoplasms which arise in non-alcoholic steatohepatitis (NASH) Stelic Animal Model (STAM) mice. Significant increase of lipid deposits, hepatocyte ballooning, fibrosis, and incidences and multiplicities of hepatocellular adenomas and carcinomas were detected in the livers of 18-week-old STAM mice. From the results of proteome analysis of STAM mice hepatocellular carcinomas, significant elevation of a novel protein, cache domain-containing 1 (CACHD1) was found. Furthermore, we observed CACHD1-positive foci in STAM mice livers, which number, area, and cell proliferation index within the foci were significantly elevated. Results of immunohistochemical and in vitro functional analysis indicated that CACHD1 may become a useful early biomarker and potential molecular target in NASH-associated hepatocarcinogenesis, which is involved in control of cell proliferation, autophagy and apoptosis.

Abstract

In the present study, potential molecular biomarkers of NASH hepatocarcinogenesis were investigated using the STAM mice NASH model, characterized by impaired insulin secretion and development of insulin resistance. In this model, 2-days-old C57BL/6N mice were subjected to a single subcutaneous (s.c.) injection of 200 μg streptozotocin (STZ) to induce diabetes mellitus (DM). Four weeks later, mice were administered high-fat diet (HFD) HFD-60 for 14 weeks (STAM group), or fed control diet (STZ group). Eighteen-week-old mice were euthanized to allow macroscopic, microscopic, histopathological, immunohistochemical and proteome analyses. The administration of HFD to STZ-treated mice induced significant fat accumulation and fibrosis development in the liver, which progressed to NASH, and rise of hepatocellular adenomas (HCAs) and carcinomas (HCCs). In 18-week-old animals, a significant increase in the incidence and multiplicity of HCAs and HCCs was found. On the basis of results of proteome analysis of STAM mice HCCs, a novel highly elevated protein in HCCs, cache domain-containing 1 (CACHD1), was chosen as a potential NASH-HCC biomarker candidate. Immunohistochemical assessment demonstrated that STAM mice liver basophilic, eosinophilic and mixed-type altered foci, HCAs and HCCs were strongly positive for CACHD1. The number and area of CACHD1-positive foci, and cell proliferation index in the area of foci in mice of the STAM group were significantly increased compared to that of STZ group. In vitro siRNA knockdown of CACHD1 in human Huh7 and HepG2 liver cancer cell lines resulted in significant inhibition of cell survival and proliferation. Analysis of the proteome of knockdown cells indicated that apoptosis and autophagy processes could be activated. From these results, CACHD1 is an early NASH-associated biomarker of liver preneoplastic and neoplastic lesions, and a potential target protein in DM/NASH-associated hepatocarcinogenesis.

Cell proliferation of rat bladder urothelium induced by nicotine is suppressed by the NADPH oxidase inhibitor, apocynin

Tobacco smoking is a major risk factor for human cancers including urinary bladder carcinoma. In a previous study, nicotine enhanced rat urinary bladder carcinogenesis in a two-stage carcinogenesis model. Nicotine also induced cytotoxicity in the bladder urothelium in a short-term study. In the present study, male rats were treated with nicotine (40 ppm) in drinking water co-administered with the NADPH oxidase inhibitor, apocynin (0, 250 or 750 mg/kg) in diet for 4 weeks. The apocynin treatment induced no clinical toxic effects. Reduction of reactive oxygen species (ROS) by apocynin was confirmed by immunohistochemistry of 8-OHdG in the bladder urothelium. Incidences of simple hyperplasia, cell proliferation and apoptosis were reduced by apocynin treatment in the bladder urothelium. However, despite reduction of cell proliferation (labeling index), apocynin did not affect the incidence of simple hyperplasia, apoptosis, or ROS generation in the kidney pelvis urothelium, in addition to 8-OHdG positivity induced by nicotine being lower. In vitro, apocynin (500 μM) reduced ROS generation, but induced cell proliferation in bladder cancer cell lines (T24 and UMUC3 cells). These data suggest that oxidative stress may play a role in the cell proliferation of the bladder urothelium induced by nicotine.

Role of γ-H2AX as a biomarker for detection of bladder carcinogens in F344 rats

Phosphorylation of histone H2AX at serine 139 (γ-H2AX) is known to be induced by direct DNA damage or cellular metabolic imbalances and malfunctions. Previous studies have reported that γ-H2AX is a useful biomarker for early detection of genotoxic bladder carcinogens in rats. The purpose of the present study was to determine the role of γ-H2AX as a biomarker for detection of non-genotoxic bladder carcinogens in rats. Six-week-old male F344 rats were treated with 15 different chemicals for 4 weeks. Immunohistochemical analyses revealed that all three genotoxic bladder carcinogens and six out of seven non-genotoxic bladder carcinogens significantly increased γ-H2AX formation in the bladder urothelium of rats. In addition, four out of five rat bladder noncarcinogens did not increase γ-H2AX formation in the bladder urothelium regardless of genotoxicity. These results suggest that γ-H2AX is a useful biomarker for detection of both genotoxic and non-genotoxic bladder carcinogens in rats.

Phosphoethanolamine Accumulation Protects Cancer Cells under Glutamine Starvation through Downregulation of PCYT2

Tolerance to severe tumor microenvironments, including hypoxia and nutrient starvation, is a common feature of aggressive cancer cells and can be targeted. However, metabolic alterations that support cancer cells upon nutrient starvation are not well understood. Here, by comprehensive metabolome analyses, we show that glutamine deprivation leads to phosphoethanolamine (PEtn) accumulation in cancer cells via the downregulation of PEtn cytidylyltransferase (PCYT2), a rate-limiting enzyme of phosphatidylethanolamine biosynthesis. PEtn accumulation correlated with tumor growth under nutrient starvation. PCYT2 suppression was partially mediated by downregulation of the transcription factor ELF3. Furthermore, PCYT2 overexpression reduced PEtn levels and tumor growth. In addition, PEtn accumulation and PCYT2 downregulation in human breast tumors correlated with poor prognosis. Thus, we show that glutamine deprivation leads to tumor progression by regulating PE biosynthesis via the ELF3-PCYT2 axis. Furthermore, manipulating glutamine-responsive genes could be a therapeutic approach to limit cancer progression.

Expression, intracellular localization, and mutation of EGFR in conjunctival squamous cell carcinoma and the association with prognosis and treatment

Purpose

Conjunctival squamous cell carcinoma (SCC) is primarily treated with surgical resection. SCC has various stages, and local recurrence is common. The purpose of this study was to determine molecular localization of epidermal growth factor receptor (EGFR) and the possibility of EGFR as a biomarker for the management of conjunctival SCC.

Methods

In this retrospective study, we performed immunohistochemistry to evaluate EGFR expression and localization in tumor cells, EGFR mutation-specific expression (E746-A750del and L858R), and human papillomavirus expression in a series of 29 conjunctival SCCs.

Results

All 29 tumors in our cohort were EGFR positive (100%). Twenty-one of 29 tumors (72%) showed focal EGFR staining, and seven (28%) showed diffuse EGFR staining. In addition, we calculated the percentages of the two most important mutations in EGFR (exon 19 746-A750del (8/29, 27.5%), exon 21 (L858R mutant (2/29, 6.8%)) in conjunctival SCCs. We observed that the translocation of EGFR from the membrane into the cytoplasm was related to clinical prognosis, as we detected correlations between EGFR cytoplasmic staining and final orbital exenteration and between decreased EGFR membrane staining and progression-free survival.

Conclusions

EGFR is important in the pathology of ocular surface squamous neoplasia including SCC and is a prognostic factor. Increased understanding of EGFR mutations may have important implications for future treatment options.

Quantitative analysis of mutagenicity and carcinogenicity of 2-amino-3-methylimidazo[4,5-f]quinoline in F344 gpt delta transgenic rats

Quantitative analysis of the mutagenicity and carcinogenicity of the low doses of genotoxic carcinogens present in food is of pressing concern. The purpose of the present study was to determine the mutagenicity and carcinogenicity of low doses of the dietary genotoxic carcinogen 2-amino-3-methylimidazo[4,5-f]quinoline (IQ). Male F344 gpt delta transgenic rats were fed diets supplemented with 0, 0.1, 1, 10 or 100 ppm IQ for 4 weeks. The frequencies of gpt transgene mutations in the liver were significantly increased in the 10 and 100 ppm groups. In addition, the mutation spectra was altered in the 1, 10 and 100 ppm groups: frequencies of G:C to T:A transversion were significantly increased in groups administered 1, 10 and 100 ppm IQ in a dose-dependent manner, and the frequencies of G:C to A:T transitions, A:T to T:A transversions and A:T to C:G transversions were significantly increased in the 100 ppm group. Increased frequencies of single base pair deletions and Spi- mutants in the liver, and an increase in glutathione S-transferase placental form (GST-P)-positive foci, a preneoplastic lesion of the liver in rats, was also observed in the 100 ppm group. In contrast, neither mutations nor mutation spectra or GST-P-positive foci were statistically altered by administration of IQ at 0.1 ppm. We estimated the point of departure for the mutagenicity and carcinogenicity of IQ using the no-observed-effect level approach and the Benchmark dose approach to characterise the dose-response relationship of low doses of IQ. Our findings demonstrate the existence of no effect levels of IQ for both in vivo mutagenicity and hepatocarcinogenicity. The findings of the present study will facilitate an understanding of the carcinogenic effects of low doses of IQ and help to determine a margin of exposure that may be useful for practical human risk assessment.

Myeloid-derived suppressor cells are essential partners for immune checkpoint inhibitors in the treatment of cisplatin-resistant bladder cancer

Myeloid-derived suppressor cells (MDSCs) are one of the key players that contribute to immune evasion. The purpose of the present study was to investigate whether MDSCs could be a novel target for the treatment of cisplatin-resistant bladder cancer. We established cisplatin-resistant bladder cancer cell lines (MB49R, MBT-2R, and T24R) and evaluated chemokine expression and MDSC expansion. We also assessed the antitumor effect by depleting MDSCs with or without a α-PD-L1 antibody using MB49R xenograft models. The chemokine expression of CXCL1, CXCL2, and CCL2 increased in cisplatin-resistant cells compared to those in their parent strains. Monocytic MDSCs (Mo-MDSCs) were observed more frequently compared to polymorphonuclear MDSCs (PMN-MDSCs) in MB49R tumors. The immunosuppressive genes arginase 1 and iNOS were comparably expressed in each MDSC subtype. In vivo, combination therapy targeting both PMN- and Mo-MDSCs using α-Gr1 and α-Ly6C antibodies significantly reduced tumor volume with increased infiltration of CD8 T cells in the tumor. Finally, co-targeting pan-MDSCs and PD-L1 remarkably reduced the tumor growth. These findings suggest that targeting MDSCs might enhance the therapeutic effect of immune checkpoint inhibitors in cisplatin-resistant bladder cancers.

Long-term administration of excess zinc impairs learning and memory in aged mice

Zinc (Zn) is an essential element, but excess amounts are known to cause neurotoxic effects. The risk of excessive Zn intake is increased by supplementing food intake with dietary supplements. Ageing affects many cellular processes that predispose individuals to neurodegeneration. Indeed, the prevalence of senile dementia such as Alzheimer's disease, Parkinson's disease, and vascular-type dementia increases with age. As such, we investigated the effects of long-term exposure to excess Zn on learning and memory in aged mice. ICR-JCL female mice (aged 26 weeks) were administered 0, 200, or 500 ppm Zn as zinc chloride in drinking water for 30 weeks. After 30-week administration, aged female animals were subjected to Y-maze, novel object recognition, and step-through passive avoidance tests. Chronic exposure to Zn did not inhibit learning and memory in the Y-maze test, but dose-dependently inhibited learning and memory in novel object recognition and step-through passive avoidance tests. These results indicate the potential for chronic Zn exposure to dose-dependently inhibit both long-term and novel object recognition memory. Results of microarray analysis revealed significant changes in gene expression of transthyretin and many olfactory receptors in the hippocampus of Zn-treated mice.

PITX1 protein interacts with ZCCHC10 to regulate hTERT mRNA transcription

Telomerase is a ribonucleoprotein ribonucleic enzyme that is essential for cellular immortalization via elongation of telomere repeat sequences at the end of chromosomes. Human telomerase reverse transcriptase (hTERT), the catalytic subunit of telomerase holoenzyme, is a key regulator of telomerase activity. Telomerase activity, which has been detected in the majority of cancer cells, is accompanied by hTERT expression, suggesting that this enzyme activity contributes to an unlimited replication potential of cancer cells via regulation of telomere length. Thus, hTERT is an attractive target for cancer-specific treatments. We previously reported that pared-like homeodomain 1 (PITX1) is a negative regulator of hTERT through direct binding to the hTERT promoter. However, the mechanism by which the function of PITX1 contributes to transcriptional silencing of the hTERT gene remains to be clarified. Here, we show that PITX1 and zinc finger CCHC-type containing 10 (ZCCHC10) proteins cooperate to facilitate the transcriptional regulation of the hTERT gene by functional studies via FLAG pull-down assay. Co-expression of PITX1 and ZCCHC10 resulted in inhibition of hTERT transcription, in melanoma cell lines, whereas mutate-deletion of homeodomain in PITX1 that interact with ZCCHC10 did not induce similar phenotypes. In addition, ZCCHC10 expression levels showed marked decrease in the majority of melanoma cell lines and tissues. Taken together, these results suggest that ZCCHC10-PITX1 complex is the functional unit that suppresses hTERT transcription, and may play a crucial role as a novel tumor suppressor complex.

A chronic toxicity study of diphenylarsinic acid in the drinking water of C57BL/6J mice for 52 weeks

Diphenylarsinic acid (DPAA), a neurotoxic organic arsenical, is present in the groundwater and soil in some regions of Japan due to illegal dumping. The purpose of the present study was to evaluate the potential toxicity of DPAA when administered to mice in their drinking water for 52 weeks. DPAA was administered to mice at concentrations of 0, 6.25, 12.5, and 25 ppm in their drinking water for 52 weeks. There were no significant differences in final body weights between the control groups and the DPAA treatment groups in male or female mice. Relative liver weights were significantly increased in males treated with 25 ppm DPAA, and absolute liver weights were significantly decreased in female mice treated with 25 ppm DPAA. In female mice, cholangitis and simple bile duct hyperplasia were observed in the 12.5 and 25 ppm DPAA groups, and focal necrosis of hepatocytes was observed in the 25 ppm DPAA group. Proteomic analysis and Ingenuity Pathway Analysis identified 18 proteins related to hepatotoxicity that were overexpressed in the female 25 ppm group. The phase I metabolic enzyme CYP2E1 was one of these overexpressed proteins. Immunostaining confirmed high expression of CYP2E1 in the livers of females in the 25 ppm group. These results suggest that DPAA is toxic to the intrahepatic bile duct epithelium and hepatocytes in female mice and that CYP2E1 might be involved in DPAA-associated toxicity. The no-observed-adverse-effect levels of DPAA were 12.5 ppm (1.6 mg/kg bw/day) for males and 6.25 ppm (1.1 mg/kg bw/day) for females under the conditions of this study.

[Refractory ascites caused by lymphatic flow disorder after stem cell transplantation for acute myeloid leukemia]

In allogeneic hematopoietic stem cell transplantation (HSCT), ascites may develop owing to several causes, including sinusoidal obstruction syndrome, infections, malignancies, and malnutrition. However, it is often difficult to determine its precise cause. Here, a 59-year-old male developed chylous ascites three months post allogeneic bone marrow transplantation for relapsed acute myeloid leukemia. None of the attempted treatments resulted in improvement. Lymphangioscintigraphy revealed a lymphatic flow disorder at the level of the cisterna chyli. Autopsy revealed no leukemic cell infiltration or graft-versus-host disease of the liver or pancreas. The pancreatic specimen revealed parenchymal fibrosis and infiltration of plasma cells, suggesting chronic inflammation in addition to pathological changes caused by acute pancreatitis. These findings indicate that acute or chronic pancreatitis caused a lymphatic flow disorder that developed into refractory ascites. Although we could not diagnose pancreatitis while the patient was alive, it is important to recognize that asymptomatic pancreatitis can develop after HSCT. Furthermore, one should attempt to make an accurate diagnosis as early as possible.

Establishment of a New Scirrhous Gastric Cancer Cell Line with FGFR2 Overexpression, OCUM-14

BACKGROUND

The prognosis of scirrhous gastric carcinoma (SGC), which is characterized by rapid infiltration and proliferation of cancer cells accompanied by extensive stromal fibrosis, is extremely poor. In this study, we report the establishment of a unique SGC cell line from a gastric cancer patient in whom an autopsy was performed.

METHODS

A new SGC cell line, OCUM-14, was established from malignant ascites of a male patient with SGC. A postmortem autopsy was performed on the patient. Characterization of OCUM-14 cells was analyzed by microscopic examination, reverse transcription polymerase chain reaction, fluorescence in situ hybridization analysis, immunohistochemical examination, CCK-8 assay, and in vivo assay.

RESULTS

OCUM-14 cells grew singly or in clusters, and were floating and round-shaped. Most OCUM-14 cells had many microvilli on their surfaces. The doubling time was 43.1 h, and the subcutaneous inoculation of 1.0 × 10⁷ OCUM-14 cells into mice resulted in 50% tumor formation. mRNA expressions of fibroblast growth factor receptor 2 (FGFR2) and human epidermal growth factor receptor 2 (HER2) were observed in OCUM-14 cells. FGFR2, but not HER2, overexpression was found in OCUM-14 cells. The heterogeneous overexpression of FGFR2 was also found in both the primary tumor and metastatic lesions of the peritoneum, lymph node, bone marrow, and lung of the patient. The FGFR2 inhibitors AZD4547 and BGJ398 significantly decreased the growth of OCUM-14 cells, while paclitaxel and 5-fluorouracil significantly decreased the proliferation of OCUM-14 cells, but cisplatin did not.

CONCLUSION

A new gastric cancer cell line, OCUM-14, was established from SGC and showed FGFR2 overexpression. OCUM-14 might be useful for elucidating the characteristic mechanisms of SGC and clarifying the effect of FGFR2 inhibitors on SGC.

Steroid sulfatase promotes invasion through epithelial-mesenchymal transition and predicts the progression of bladder cancer

Androgen signal has been recently suggested to be associated with the progression of bladder cancer. Steroid sulfatase (STS) is a steroid sulfate activation enzyme, considered to be one of the key enzymes in the androgen signaling pathway. However, the role of STS in bladder cancer has not been elucidated. The purpose of the present study was to determine the clinical and functional significance of STS in bladder cancer. Immunohistochemical analysis of surgical specimens obtained by radical cystectomy (n=114) demonstrated that overexpression of STS was associated with the invasion of bladder cancer, as evidenced by the incidence of STS-positive cancers (11.5 and 37.1% in non-muscle invasive and muscle invasive bladder cancers, respectively; P=0.003). STS-positive cancer demonstrated shorter recurrence-free survival and cancer-specific survival (P=0.0027 and 0.0030, respectively). Furthermore, knockdown of STS significantly reduced cell migration and invasion capacities of bladder cancer cells (P<0.001 and P=0.005, respectively), accompanied by the upregulation of E-cadherin and downregulation of vimentin. In summary, the present study demonstrated that STS promotes the invasion capability of bladder cancer via regulation of the epithelial-mesenchymal transition, and may be a useful marker for predicting the progression of bladder cancers.

Quantitative Approaches to Assess Key Carcinogenic Events of Genotoxic Carcinogens

Chemical carcinogenesis is a multistep process. Genotoxic carcinogens, which are DNA-reactive, induce DNA adduct formation and genetic alterations in target cells, thereby generating mutated cells (initiation). Subsequently, preneoplastic lesions appear through clonal proliferation of the mutated cells and transform into tumors (promotion and progression). Many factors may influence these processes in a dose-dependent manner. Therefore, quantitative analysis plays an important role in studies on the carcinogenic threshold of genotoxic carcinogens. Herein, we present data on the relationship between key carcinogenic events and their deriving point of departure (PoD). Their PoDs were also compared to those of the carcinogenesis pathway. In an experiment, the liver of rats exposed to 2-amino-3,8-dimethylimidazo-(4,5-f)quinoxaline (MeIQx) was examined to determine the formation of MeIQx-DNA adducts, generation of mutations at LacI transgene, and induction of preneoplastic glutathione S-transferase placental form (GST-P)-positive foci and tumors (benign and malignant). The PoDs of the above key events in the carcinogenicity of MeIQx were increased as the carcinogenesis advanced; however, these PoDs were lower than those of tumor induction. Thus, the order of key events during tumor induction in the liver was as follows: formation of DNA adducts << Mutations << GST-positive foci (preneoplasia) << Tumor (adenoma and carcinoma). We also obtained similar data on the genotoxic and carcinogenic PoDs of other hepatocarcinogens, such as 2-amino-3,8-dimethylimidazo(4,5-f)quinoline. These results contribute to elucidating the existence of a genotoxic and carcinogenic threshold.

Chronic dietary toxicity and carcinogenicity studies of dammar resin in F344 rats

Dammar resin is a natural food additive and flavoring substance present in many foods and drinks. The present study evaluates the chronic toxicity and carcinogenicity of dietary dammar resin in F344 rats. Dietary concentrations in the 52-week chronic toxicity study were 0, 0.03, 0.125, 0.5, or 2%. The major treatment-related deleterious effects were body weight suppression, increased relative liver weight, and low hemoglobin levels in males and females. Foci of cellular alteration in the liver were observed in the male 2% group, but not in any other group. The no-observed-adverse-effect level for chronic toxicity was 0.125% for males (200.4 mg/kg b.w./day) and females (241.9 mg/kg b.w./day). Dietary concentrations in the 104-week carcinogenicity study were 0, 0.03, 0.5, or 2%. Dammar resin induced hemorrhagic diathesis in males and females, possibly via the inhibition of extrinsic and intrinsic coagulation pathways. Incidences of hepatocellular adenomas and carcinomas were significantly increased in the male 2% group, but not in any other group. In the 4-week subacute toxicity study, the livers of male rat-fed diet-containing 2% dammar resin had increased levels of protein oxidation and increased the expression of two anti-apoptotic and seven cytochrome P450 (CYP) genes. There was also an increased tendency of oxidative DNA damage. These findings demonstrate that dammar resin is hepatocarcinogenic in male F344 rats and underlines the roles of inhibition of apoptosis, induction of CYP enzymes, and oxidative stress in dammar resin-induced hepatocarcinogenesis.

In vivo positive mutagenicity of 1,4-dioxane and quantitative analysis of its mutagenicity and carcinogenicity in rats

1,4-Dioxane is a widely used synthetic industrial chemical and its contamination of drinking water and food is a potential health concern. It induces liver tumors when administered in the drinking water to rats and mice. However, the mode of action (MOA) of the hepatocarcinogenicity of 1,4-dioxane remains unclear. Importantly, it is unknown if 1,4-dioxane is genotoxic, a key consideration for risk assessment. To determine the in vivo mutagenicity of 1,4-dioxane, gpt delta transgenic F344 rats were administered 1,4-dioxane at various doses in the drinking water for 16 weeks. The overall mutation frequency (MF) and A:T- to -G:C transitions and A:T- to -T:A transversions in the gpt transgene were significantly increased by administration of 5000 ppm 1,4-dioxane. A:T- to -T:A transversions were also significantly increased by administration of 1000 ppm 1,4-dioxane. Furthermore, the DNA repair enzyme MGMT was significantly induced at 5000 ppm 1,4-dioxane, implying that extensive genetic damage exceeded the repair capacity of the cells in the liver and consequently led to liver carcinogenesis. No evidence supporting other MOAs, including induction of oxidative stress, cytotoxicity, or nuclear receptor activation, that could contribute to the carcinogenic effects of 1,4-dioxane were found. These findings demonstrate that 1,4-dioxane is a genotoxic hepatocarcinogen and induces hepatocarcinogenesis through a mutagenic MOA in rats. Because our data indicate that 1,4-dioxane is a genotoxic carcinogen, we estimated the point of departure of the mutagenicity and carcinogenicity of 1,4-dioxane using the no-observed effect-level approach and the Benchmark dose approach to characterize its dose-response relationship at low doses.

Generation of Rat Monoclonal Antibodies Against a Deubiquitinase, Ovarian Tumor Domain-Containing Protein 1

Ovarian tumor domain-containing protein 1 (OTUD1), an OTU-family deubiquitinating enzyme, has been reported to be involved in cancer progression through the regulation of p53 and SMAD7. However, the precise pathophysiological functions of OTUD1 remain elusive. Here, we report the establishment of OTUD1-specific monoclonal antibodies (mAbs), using the rat medial iliac lymph node method. The generated antibodies recognize the N-terminal portion (aa. 1-290) of human and mouse OTUD1 proteins. In addition, immunofluorescent staining and subcellular fractionation analyses using these antibodies indicated that OTUD1 is predominantly localized in the cytosol. Thus, these mAbs can be further used to elucidate cellular functions of OTUD1 and its involvement in processes such as cancer progression.

Generation of Rat Monoclonal Antibodies Specific for DZIP3

DAZ interacting zinc finger 3 (DZIP3), an RNA-binding RING-type ubiquitin ligase, has been reported to be involved in multiple physiological functions, including the regulation of chemokine- or estradiol-induced gene expression, self-renewal, and maintaining pluripotency in mouse embryonic stem cells. However, the precise cellular functions of DZIP3 remain elusive. In this study, we report the establishment of DZIP3-specific monoclonal antibodies (MAbs), using the rat medial iliac lymph node method. In immunoblotting analyses, our antibodies detected endogenous human and mouse DZIP3. In addition, immunoprecipitation analyses revealed the availability of these antibodies for human or mouse DZIP3. Thus, these MAbs will be available to elucidate cellular functions of DZIP3.

Hypoxia-inducible factor-2 alpha up-regulates CD70 under hypoxia and enhances anchorage-independent growth and aggressiveness in cancer cells

Hypoxia-inducible factors (HIFs) facilitate cellular adaptation to environmental stress such as low oxygen conditions (hypoxia) and consequently promote tumor growth. While HIF-1α functions in cancer progression have been increasingly recognized, the contribution of HIF-2α remains widely unclear despite accumulating reports showing its overexpression in cancer cells. Here, we report that HIF-2α up-regulates the expression of CD70, a cancer-related surface antigen that improves anchorage-independent growth in cancer cells and is associated with poor clinical prognosis, which can be induced via epigenetic modifications mediated by DNMT1. The ablation of CD70 by RNAi led to decreased colony forming efficiency in soft agar. Most strikingly, we identified the emergence of CD70-expressing cells derived from CD70-negative cell lines upon prolonged hypoxia exposure or DNMT1 inhibition, both of which significantly reduced CpG-nucleotide methylations within CD70 promoter region. Interestingly, DNMT1 expression was decreased under hypoxia, which was rescued by HIF-2α knockdown. In addition, the expression of CD70 and colony forming efficiency in soft agar were decreased by knockdown of HIF-2α. These findings indicate that CD70 expression and an aggressive phenotype of cancer cells is driven under hypoxic conditions and mediated by HIF-2α functions and epigenetic modifications. This provides additional insights into the role of HIF-2α in coordinated regulation of stem-like functions and epigenetics that are important for cancer progression and may present additional targets for the development of novel combinatorial therapeutics.

Alpha-synuclein facilitates to form short unconventional microtubules that have a unique function in the axonal transport

Although α-synuclein (αSyn) has been linked to Parkinson’s disease (PD), the mechanisms underlying the causative role in PD remain unclear. We previously proposed a model for a transportable microtubule (tMT), in which dynein is anchored to a short tMT by LIS1 followed by the kinesin-dependent anterograde transport; however the mechanisms that produce tMTs have not been determined. Our in vitro investigations of microtubule (MT) dynamics revealed that αSyn facilitates the formation of short MTs and preferentially binds to MTs carrying 14 protofilaments (pfs). Live-cell imaging showed that αSyn co-transported with dynein and mobile βIII-tubulin fragments in the anterograde transport. Furthermore, bi-directional axonal transports are severely affected in αSyn and γSyn depleted dorsal root ganglion neurons. SR-PALM analyses further revealed the fibrous co-localization of αSyn, dynein and βIII-tubulin in axons. More importantly, 14-pfs MTs have been found in rat femoral nerve tissue, and they increased approximately 19 fold the control in quantify upon nerve ligation, indicating the unconventional MTs are mobile. Our findings indicate that αSyn facilitates to form short, mobile tMTs that play an important role in the axonal transport. This unexpected and intriguing discovery related to axonal transport provides new insight on the pathogenesis of PD.

Enhanced Susceptibility of Ogg1 Mutant Mice to Multiorgan Carcinogenesis

The role of deficiency of oxoguanine glycosylase 1 (Ogg1) Mmh homolog, a repair enzyme of the 8-hydroxy-2’-deoxyguanosine (8-OHdG) residue in DNA, was investigated using the multiorgan carcinogenesis bioassay in mice. A total of 80 male and female six-week-old mice of C57BL/6J background carrying a mutant Mmh allele of the Mmh/Ogg1 gene (Ogg1^−/−) and wild type (Ogg1^+/+) mice were administered N-diethylnitrosamine (DEN), N-methyl-N-nitrosourea (MNU), N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN), N-bis (2-hydroxypropyl) nitrosamine (DHPN) and 1,2-dimethylhydrazine dihydrochloride (DMH) (DMBDD) to induce carcinogenesis in multiple organs, and observed up to 34 weeks. Significant increase of lung adenocarcinomas incidence was observed in DMBDD-treated Ogg1^−/− male mice, but not in DMBDD-administered Ogg1^+/+ animals. Furthermore, incidences of lung adenomas were significantly elevated in both Ogg1^−/− males and females as compared with respective Ogg1^−/− control and DMBDD-treated Ogg1^+/+ groups. Incidence of total liver tumors (hepatocellular adenomas, hemangiomas and hemangiosarcomas) was significantly higher in the DMBDD-administered Ogg1^−/− males and females. In addition, in DMBDD-treated male Ogg1^−/− mice, incidences of colon adenomas and total colon tumors showed a trend and a significant increase, respectively, along with significant rise in incidence of simple hyperplasia of the urinary bladder, and a trend to increase for renal tubules hyperplasia in the kidney. Furthermore, incidence of squamous cell hyperplasia in the forestomach of DMBDD-treated Ogg1^−/− male mice was significantly higher than that of Ogg1^+/+ males. Incidence of small intestine adenomas in DMBDD Ogg1^−/− groups showed a trend for increase, as compared to the wild type mice. The current results demonstrated increased susceptibility of Ogg1 mutant mice to the multiorgan carcinogenesis induced by DMBDD. The present bioassay could become a useful tool to examine the influence of various targets on mouse carcinogenesis.

PIK3CA mutation as a distinctive genetic feature of non-small cell lung cancer with chronic obstructive pulmonary disease: A comprehensive mutational analysis from a multi-institutional cohort

OBJECTIVES

Non-small cell lung cancer (NSCLC) and chronic obstructive pulmonary disease (COPD) have been proposed to have a mutual developmental mechanism, but their association has not been fully understood. We aimed to examine the association of the mutational landscape of NSCLC with co-morbid COPD.

MATERIALS AND METHODS

A total of 197 surgical specimens of early stage NSCLC were retrospectively collected from two independent sources, namely, the Japan Molecular Epidemiology for Lung Cancer Study and the Osaka City University Hospital cohort from 2010 to 2013. COPD and its severity were defined by the Global Initiative for Chronic Obstructive Lung Disease (GOLD) guidelines and grading system. For molecular profiling of NSCLC patients with COPD, the extracted DNAs were deep-sequenced using next generation sequence technologies for somatic mutations in a maximum 72 cancer-associated genes. Logistic regression analysis was performed to evaluate the impact of COPD on the somatic mutations.

RESULTS

The COPD group (n=77), including 56 GOLD 1 and 21 GOLD 2 or 3 patients, had 58 squamous cell lung carcinoma (SCC) cases and 19 adenocarcinoma cases. The non-COPD group (n=120) had 53 SCC cases, 64 adenocarcinoma cases, and three cases with other histology. The frequency of PIK3CA mutation was significantly higher in the COPD group than in the non-COPD group (10.4% vs. 1.7%, p=0.015). Meanwhile, NFE2L2 mutation was observed only in SCC cases, with no difference in the frequency between the two groups (17.2% vs. 17.0%). In the multivariate logistic regression model with consideration for COPD status, age, smoking dose, pathological stage, and histology, significantly more PIK3CA mutation was observed in the presence of COPD (odds ratio=5.31, 95% CI: 1.03-27.29, p=0.046).

CONCLUSIONS

PIK3CA mutation is a distinctive genetic feature of NSCLC with COPD, regardless of age, smoking dose, pathological stage, and histology.

A carcinogenicity study of diphenylarsinic acid in F344 rats in drinking water for 104 weeks

Diphenylarsinic acid (DPAA), a neurotoxic organic arsenical used as a chemical warfare agent, is present in the groundwater and soil in some regions of Japan due to illegal dumping after World War II. We previously demonstrated that DPAA promotes diethylnitrosamine-induced liver carcinogenesis in a medium-term rat liver bioassay. The purpose of the present study was to evaluate the potential carcinogenicity of DPAA, including investigation of whether the bile duct hyperplasia in the liver that was observed in a previous 52 week rat chronic study develops into a tumor, when administered to rats in their drinking water for 104 weeks. DPAA was administered to groups 1-4 at concentrations of 0, 5, 10, and 20 ppm in their drinking water for 104 weeks. A significant decrease in survival rate was found for females in the 20 ppm DPAA group. Body weights of males in the 20 ppm and females in the 10 and 20 ppm DPAA groups were significantly decreased compared to the controls. Overall histopathological evaluation of neoplasms in all tissues showed no significant increase of tumor incidence in any organ or tissue of the 5, 10, or 20 ppm DPAA-treated male or female F344 rats. In conclusion, the present study demonstrated that DPAA is not a complete carcinogen in male or female F344 rats.

Chemopreventive Action by Ethanol-extracted Brazilian Green Propolis on Post-initiation Phase of Inflammation-associated Rat Colon Tumorigenesis

BACKGROUND/AIM

Propolis has since long been utilized in numerous folk medicines with a variety of medicinal properties. In this study, the effects of ethanol-extracted (EEP) and water-extracted (WEP) Brazilian green propolis on the post-initiation phase of inflammation-associated rat colon tumorigenesis were directly compared.

MATERIALS AND METHODS

Male F344 rats at 6 weeks of age were subcutaneously injected with 1,2-dimethylhydrazine (DMH) at 40 mg/kg body weight twice during the first week, followed by 1% dextran sodium sulfate (DSS) in drinking water for one week. After a 1-week no-treatment period, animals were administered either basal Oriental MF powdered diet, or 1% EEP or 1% WEP in the basal diet until week 32.

RESULTS

Post-initiation treatment with EEP significantly reduced the multiplicity of colorectal carcinomas compared to the control (0.40±0.13/rat vs. 2.29±0.84/rat, respectively, p<0.05), and EEP also reduced the tumor volume. Immunohistochemically, expression of inflammation-associated proteins inducible nitric oxide synthase, tumor necrotic factor alpha, nuclear factor kappa B and glutathione peroxidase-2 were significantly diminished in colorectal tumors from EEP-treated rats.

CONCLUSION

Suppression of inflammation and oxidative stress, which had been triggered by DMH and promoted by DSS, was a primary mechanism by which EEP suppressed carcinogenesis.

Carbonic anhydrase 2 is a novel invasion-associated factor in urinary bladder cancers

Rat bladder cancer is nearly always papillary non-invasive urothelial carcinoma (UC). To establish an animal model mimicking invasive UC that arises from papillary non-invasive UC in the bladder, male human c-Ha-ras proto-oncogene transgenic rats (Hras128) were treated with 0.05% N-butyl-N-(hydroxybutyl)nitrosameine (BBN) in their drinking water and/or 0.1% phenylethyl isothiocyanate (PEITC) in their diet as follows: BBN (8 weeks)→PEITC (8 weeks); PEITC (8 weeks)→BBN (8 weeks); BBN alone (16 weeks); PEITC alone (16 weeks); and no treatment. At the end of week 16, the highest incidence of invasive UC was observed in the BBN→PEITC group. Therefore, we used Hras128 rats treated with BBN followed by PEITC as a model of invasive bladder cancer to identify invasion-associated proteins. Proteome analysis was performed to compare the protein profiles of invasive and non-invasive UC in Hras128 rats. We identified 49 proteins that were either overexpressed or underexpressed in invasive UC but not in non-invasive UC. Immunohistochemical analysis of carbonic anhydrase 2 (CA2), an overexpressed protein, showed that the relative number of CA2-positive UC was significantly higher for invasive UC compared to non-invasive UC in rats. Moreover, the incidence of CA2-positive cancers was also significantly higher for human muscle-invasive bladder cancer (MIBC) compared to non-MIBC (NMIBC) and was positively associated with the progression of NMIBC. Our findings indicate that CA2 is an invasion-associated factor and suggest that it could serve as a potential therapeutic molecular target for bladder cancers.

B cells in tertiary lymphoid structures are associated with favorable prognosis in gastric cancer

BACKGROUND

The role of tumor-infiltrating B cells in the tumor microenvironment is still unclear. Recent studies have reported that B cells and tertiary lymphoid structures (TLSs) that contain B cell follicles correlate with the favorable prognosis of cancer patients. The aim of this study was to investigate the association between tumor-infiltrating B cells and clinicopathological features in gastric cancer.

METHODS

Tumor blocks were obtained from 226 patients with stage Ib to stage IV gastric cancer. The density of CD20⁺ B cells within the tumor and in the invasive margin area was assessed using immunohistochemistry. We also evaluated CD3⁺ T cells, CD21⁺ follicular dendritic cells, Bcl6⁺ germinal center B cells, and PNAd⁺ high endothelial venules to show the presence of TLSs.

RESULTS

Tumor-infiltrating B cells were mostly organized as clusters that were surrounded by CD3⁺ T cells. The B cell area contained follicular dendritic cells and some clusters contained Bcl6⁺ B cells. High endothelial venules were present around follicles. We identified these follicles as TLSs. A high number of CD20⁺ B cells were associated with significantly better overall survival, and multivariate analysis also showed that CD20 high was one of the independent predictors of prognosis. In addition, there was a significant correlation between CD20⁺ B cell and CD8⁺ T cell infiltration.

CONCLUSIONS

B cells mostly infiltrated tumors as TLSs and were associated with better prognosis in patients with gastric cancer.

Proteome Characteristics of Non-Alcoholic Steatohepatitis Liver Tissue and Associated Hepatocellular Carcinomas

To uncover mechanisms of nonalcoholic steatohepatitis (NASH) associated hepatocarcinogenesis, we compared the proteomes of human NASH-associated liver biopsies, resected hepatocellular carcinomas (HCCs) and HCCs of HCV⁺ patients with normal liver tissue of patients with gastrointestinal tumor metastasis, in formalin-fixed paraffin-embedded samples obtained after surgery in our hospital during the period from 2006 to 2011. In addition, proteome analysis of liver tumors in male STAM NASH-model mice was performed. Similar changes in the proteome spectrum such as overexpression of enzymes involved in lipid, cholesterol and bile acid biosynthesis and examples associated with suppression of fatty acid oxidation and catabolism, alcohol metabolism, mitochondrial function as well as low expression levels of cytokeratins 8 and 18 were observed in both human NASH biopsies and NASH HCCs, but not HCV⁺ HCCs. Alterations in downstream protein expression pointed to significant activation of transforming growth factor β, SMAD family member 3, β-catenin, Nrf2, SREBP-LXRα and nuclear receptor-interacting protein 1 (NRIP1), and inhibition of PPARs and p53 in human NASH biopsies and/or HCCs, suggesting their involvement in accumulation of lipids, development of fibrosis, oxidative stress, cell proliferation and suppression of apoptosis in NASH hepatocarcinogenesis. In STAM mice, PPARs inhibition was not obvious, while expression of cytokeratins 8 and 18 was elevated, indicative of essential differences between human and mouse NASH pathogenesis.

Diphenylarsinic acid exerts promotion effects on hepatobiliary carcinogenesis in a rat medium-term multiorgan carcinogenicity bioassay

We have previously demonstrated that diphenylarsinic acid (DPAA) promotes liver carcinogenesis in rats in a medium-term liver carcinogenicity bioassay. However, the effects of DPAA on other organs have not been determined. In the present study, the effects of DPAA on carcinogenesis were investigated using a rat multiorgan carcinogenicity bioassay. A total of 60 six-week-old male F344 rats were treated with the carcinogens diethylnitrosamine, N-butyl-N-(4-hydroxybutyl) nitrosamine, N-methyl-N-nitrosourea, N-bis (2-hydroxypropyl) nitrosamine, and 1,2-dimethylhydrazine dihydrochloride to initiate carcinogenesis in multiple organs. After initiation, DPAA was given at a dose of 0, 5, or 20 ppm in drinking water for 27 weeks. The incidences of moderate and severe bile duct hyperplasia were significantly increased in the 20 ppm DPAA group (29.4%, 70.6%, respectively) compared with the 0 ppm DPAA group (0%, 0%, respectively), and the incidence and multiplicity of cholangioma were significantly increased in the 20 ppm DPAA group (29.4%, 0.4 ± 0.8/rat) compared with the 0 ppm DPAA group (0%, 0/rat). The total number and average area of glutathione S-transferase placenta form-positive foci, preneoplastic lesions in rat livers, were significantly increased in the 20 ppm DPAA group (10.5 ± 2.2/cm², 5.3 ± 1.7 mm²/cm²) compared with the 0 ppm DPAA group (6.2 ± 2.9/cm², 2.4 ± 1.4 mm²/cm²). In conclusion, our results demonstrate that DPAA promotes hepatobiliary carcinogenesis in a rat medium-term multiorgan carcinogenicity bioassay; no promotion effects were observed in other organs.

Preventive Effects of Spirogyra neglecta and a Polysaccharide Extract against Dextran Sodium Sulfate Induced Colitis in Mice

Ulcerative colitis (UC) results from colonic epithelial barrier defects and impaired mucosal immune responses. In this study, we aimed to investigate the modifying effects of a Spirogyra neglecta extract (SNE), a polysaccharide extract (PE) and a chloroform fraction (CF) on dextran sodium sulfate (DSS)-induced colitis in mice and to determine the mechanisms. To induce colitis, ICR mice received 3% DSS in their drinking water for 7 days. Seven days preceding the DSS treatment, oral administration of SNE, PE and CF at doses of 50, 25 and 0.25 mg/kg body weight (low dose), 200, 100 and 1 mg/kg body weight (high dose) and vehicle was started and continued for 14 days. Histologic findings showed that DSS-induced damage of colonic epithelial structure and inflammation was attenuated in mice pre-treated with SNE, PE and CF. Furthermore, SNE and PE significantly protected colonic epithelial cells from DSS-induced cell cycle arrest, while SNE, PE and CF significantly diminished apoptosis. Proteome analysis demonstrated that SNE and PE might ameliorate DSS-induced colitis by inducing antioxidant enzymes, restoring impaired mitochondria function, and regulating inflammatory cytokines, proliferation and apoptosis. These results suggest that SNE and PE could prevent DSS-induced colitis in ICR mice by protection against and/or aiding recovery from damage to the colonic epithelium, reducing ROS and maintaining normal mitochondrial function and apoptosis.