Mechanisms of pulmonary disease in F344 rats after workplace-relevant inhalation exposure to cross-linked water-soluble acrylic acid polymers.

BACKGROUND: Recently in Japan, six workers at a chemical plant that manufactures resins developed interstitial lung diseases after being involved in loading and packing cross-linked water-soluble acrylic acid polymers (CWAAPs). The present study focused on assessing lung damage in rats caused by workplace-relevant inhalation exposure to CWAAP and investigated the molecular and cellular mechanisms involved in lung lesion development. METHODS: Using a whole-body inhalation exposure system, male F344 rats were exposed once to 40 or 100 mg/m3 of CWAAP-A for 4 h or to 15 or 40 mg/m3 of CWAAP-A for 4 h per day once per week for 2 months (9 exposures). In a separate set of experiments, male F344 rats were administered 1 mg/kg CWAAP-A or CWAAP-B by intratracheal instillation once every 2 weeks for 2 months (5 doses). Lung tissues, mediastinal lymph nodes, and bronchoalveolar lavage fluid were collected and subjected to biological and histopathological analyses. RESULTS: A single 4-h exposure to CWAAP-A caused alveolar injury, and repeated exposures resulted in regenerative changes in the alveolar epithelium with activation of TGFß signaling. During the recovery period after the last exposure, some alveolar lesions were partially healed, but other lesions developed into alveolitis with fibrous thickening of the alveolar septum. Rats administered CWAAP-A by intratracheal instillation developed qualitatively similar pulmonary pathology as rats exposed to CWAAP-A by inhalation. At 2 weeks after intratracheal instillation, rats administered CWAAP-B appeared to have a slightly higher degree of lung lesions compared to rats administered CWAAP-A, however, there was no difference in pulmonary lesions in the CWAAP-A and CWAAP-B exposed rats examined 18 weeks after administration of these materials. CONCLUSIONS: The present study reports our findings on the cellular and molecular mechanisms of pulmonary disease in rats after workplace-relevant inhalation exposure to CWAAP-A. This study also demonstrates that the lung pathogenesis of rats exposed to CWAAP-A by systemic inhalation was qualitatively similar to that of rats administered CWAAP-A by intratracheal instillation.

Pulmonary dust foci as rat pneumoconiosis lesion induced by titanium dioxide nanoparticles in 13-week inhalation study.

BACKGROUND: Most toxicological studies on titanium dioxide (TiO2) particles to date have concentrated on carcinogenicity and acute toxicity, with few studies focusing of pneumoconiosis, which is a variety of airspace and interstitial lung diseases caused by particle-laden macrophages. The present study examined rat pulmonary lesions associated with pneumoconiosis after inhalation exposure to TiO2 nanoparticles (NPs). METHODS: Male and female F344 rats were exposed to 6.3, 12.5, 25, or 50 mg/m3 anatase type TiO2 NPs for 6 h/day, 5 days/week for 13 weeks using a whole-body inhalation exposure system. After the last exposure the rats were euthanized and blood, bronchoalveolar lavage fluid, and all tissues including lungs and mediastinal lymph nodes were collected and subjected to biological and histopathological analyses. RESULTS: Numerous milky white spots were present in the lungs after exposure to 25 and 50 mg/m3 TiO2 NPs. Histopathological analysis revealed that the spots were alveolar lesions, characterized predominantly by the agglomeration of particle-laden macrophages and the presence of reactive alveolar epithelial type 2 cell (AEC2) hyperplasia. We defined this characteristic lesion as pulmonary dust foci (PDF). The PDF is an inflammatory niche, with decreased vascular endothelial cells in the interstitium, and proliferating AEC2 transformed into alveolar epithelial progenitor cells. In the present study, the AEC2 in the PDF had acquired DNA damage. Based on PDF induction, the lowest observed adverse effect concentration for pulmonary disorders in male and female rats was 12.5 mg/m3 and 6.3 mg/m3, respectively. The no observed adverse effect concentration for male rats was 6.3 mg/m3. There was a sex difference in lung lesion development, with females showing more pronounced lesion parameters than males. CONCLUSIONS: Inhalation exposure to TiO2 NPs caused PDF, an air-space lesion which is an alveolar inflammatory niche containing particle-laden macrophages and proliferating AEC2. These PDFs histopathologically resemble some pneumoconiosis lesions (pulmonary siderosis and hard metal pneumoconiosis) in workers and lung disease in smokers, suggesting that PDFs caused by exposure to TiO2 NPs in rats are an early pneumoconiosis lesion and may be a common alveolar reaction in mammals.

Dose-response relationship of pulmonary disorders by inhalation exposure to cross-linked water-soluble acrylic acid polymers in F344 rats.

BACKGROUND: In Japan, six workers handling cross-linked water-soluble acrylic acid polymer (CWAAP) at a chemical plant suffered from lung diseases, including fibrosis, interstitial pneumonia, emphysema, and pneumothorax. We recently demonstrated that inhalation of CWAAP-A, one type of CWAAP, causes pulmonary disorders in rats. It is important to investigate dose-response relationships and recoverability from exposure to CWAAPs for establishing occupational health guidelines, such as setting threshold limit value for CWAAPs in the workplace. METHODS: Male and female F344 rats were exposed to 0.3, 1, 3, or 10 mg/m3 CWAAP-A for 6 h/day, 5 days/week for 13 weeks using a whole-body inhalation exposure system. At 1 h, 4 weeks, and 13 weeks after the last exposure the rats were euthanized and blood, bronchoalveolar lavage fluid, and all tissues including lungs and mediastinal lymph nodes were collected and subjected to biological and histopathological analyses. In a second experiment, male rats were pre-treated with clodronate liposome or polymorphonuclear leukocyte-neutralizing antibody to deplete macrophages or neutrophils, respectively, and exposed to CWAAP-A for 6 h/day for 2 days. RESULTS: CWAAP-A exposure damaged only the alveoli. The lowest observed adverse effect concentration (LOAEC) was 1 mg/m3 and the no observed adverse effect concentration (NOAEC) was 0.3 mg/m3. Rats of both sexes were able to recover from the tissue damage caused by 13 weeks exposure to 1 mg/m3 CWAAP-A. In contrast, tissue damage caused by exposure to 3 and 10 mg/m3 was irreversible due to the development of interstitial lung lesions. There was a gender difference in the recovery from CWAAP-A induced pulmonary disorders, with females recovering less than males. Finally, acute lung effects caused by CWAAP-A were significantly reduced by depletion of alveolar macrophages. CONCLUSIONS: Pulmonary damage caused by inhalation exposure to CWAAP-A was dose-dependent, specific to the lung and lymph nodes, and acute lung damage was ameliorated by depleting macrophages in the lungs. CWAAP-A had both a LOAEC and a NOAEC, and tissue damage caused by exposure to 1 mg/m3 CWAAP-A was reversible: recovery in female rats was less than for males. These findings indicate that concentration limits for CWAAPs in the workplace can be determined.

Nuclear import of IER5 is mediated by a classical bipartite nuclear localization signal and is required for HSF1 full activation.

IER5 gene encodes an activator of HSF1 and is a p53 target gene. The IER5 protein forms a ternary complex with HSF1 and PP2A, and promotes PP2A-dependent dephosphorylation of HSF1 at a number of serine and threonine residues. This hypo-phosphorylated form of HSF1 is transcriptionally active and has been suggested to be responsible for the HSF1 activation observed in cancers. Here we report that IER5 possess a classical bipartite nuclear localization signal (NLS) at amino acids 217-244 that is highly conserved among species and that mediates complex formation with importin-α and importin-ß. We also demonstrate that the intact NLS is essential for HSF1 dephosphorylation and full activation by IER5. Thus, nuclear import of IER5 via importin-α and importin-ß may be essential for IER5 function.

Carcinogenicity and chronic toxicity of acrolein in rats and mice by two-year inhalation study.

The carcinogenicity and chronic toxicity of acrolein was examined by whole body inhalation to groups of 50 F344/DuCrlCrlj rats and 50 B6D2F1/Crlj mice of both sexes for two years. The concentration of acrolein was 0, 0.1, 0.5 or 2 ppm (v/v) for male and female rats; and 0, 0.1, 0.4 or 1.6 ppm for male and female mice. Two-year administration of acrolein induced the squamous cell carcinomas in nasal cavity which is rare tumor in one male and two female rats. In females, rhabdomyoma in nasal cavity was observed in four rats exposed to 2 ppm. In mice, since the survival rate of male and female of mice control group were lowered than 25% in late of the administration periods due to renal lesion and/or amyloid deposition, the mice study was terminated at 93rd week in males, and was terminated at 99th week in females. The incidences of adenomas in nasal cavity were observed in 16 females and significantly increased only in female mice. Thus, acrolein is carcinogenic in two species, i.e. rats and mice. Additionally, non-neoplastic nasal cavity lesions in rats and mice were observed.

Genomic alterations in STK11 can predict clinical outcomes in cervical cancer patients.

OBJECTIVE: Cervical cancer is the fourth most common cause of cancer-related deaths in Asian women, due to its poor prognosis. This study aimed to decipher genomic alteration profiles of a cohort of Japanese cervical cancer patients to understand why certain patients benefited from molecular targeted therapies and their prognostic significance. METHODS: During 2008-2018, 154 cervical cancer patients underwent a potentially curative resection procedure at the National Cancer Center Hospital. Genomic DNA samples were analyzed using Ion AmpliSeq™ Cancer Hotspot Panel v2. Alterations in the copy number of PIK3CA, ERBB2, PTEN, and STK11 were detected using the TaqMan assay. HPV-positive results were confirmed by genomic testing and in situ hybridization assay. RESULTS: The frequency of genomic alterations in PIK3CA (36%), STK11 (16%), PTEN (11%), TP53 (11%), and KRAS (8%) was >5%. KRAS mutations were preferentially detected in patients with adenocarcinomas, and the frequency of PIK3CA mutations in patients with squamous cell carcinomas was higher than that in patients with other histological cancer types. HPV-positive results were observed in 139/154 (90.3%) patients, and TP53 mutants were detected in HPV-negative specimens. In this study, the overall survival of patients with genomic alterations in STK11 was worse than in patients with wild-type STK11 (hazard ratio = 10.6, P = 0.0079) and TCGA dataset (hazard ratio = 2.46, P = 0.029). CONCLUSIONS: More than one-third of Japanese cervical cancer patients exhibit mutations targeted by molecular targeted therapies. We have proposed the prognostic value of STK11 genomic alterations.

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.

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.

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.

Anti-PD-L1 treatment enhances antitumor effect of everolimus in a mouse model of renal cell carcinoma.

Immunotherapy based on blockade of the programmed death-1 (PD-1)/programmed death-ligand 1 (PD-L1) axis has shown promising clinical activity for renal cell carcinoma (RCC) patients; however, the most effective use of these agents in combination with conventional targeted therapy remains to be resolved. Here we evaluated the therapeutic efficacy of the combination of the mTOR inhibitor everolimus (EVE) and anti-PD-L1 using an immunocompetent mouse model of RCC. We first assessed the in vitro effect of EVE on PD-L1 expression in the human 786-O and mouse RENCA RCC cell lines and found that EVE upregulated PD-L1 expression in these RCC cell lines. We then treated RENCA tumor-bearing mice with EVE and found that PD-L1 expression was also increased in tumor cells after EVE treatment. To determine the antitumor effects of EVE alone, anti-PD-L1 alone, and EVE in combination with anti-PD-L1, we evaluated their antitumor effects on RENCA tumor-bearing mice. A significant decrease in the tumor burden was observed in the EVE alone but not in the anti-PD-L1 alone treatment group compared with the control group. Importantly, the combination of EVE with anti-PD-L1 significantly reduced tumor burden compared with the EVE alone treatment, increasing tumor infiltrating lymphocytes (TILs) and the ratio of cytotoxic CD8+ T cells to TILs. The results of the present study demonstrated that anti-PD-L1 treatment enhanced the antitumor effect of EVE in a mouse model, supporting a direct translation of this combination strategy to the clinic for the treatment of RCC.

Role of deltaNp63(pos)CD44v(pos) cells in the development of N-nitroso-tris-chloroethylurea-induced peripheral-type mouse lung squamous cell carcinomas.

The role of cells expressing stem cell markers deltaNp63 and CD44v has not yet been elucidated in peripheral-type lung squamous cell carcinoma (pLSCC) carcinogenesis. Female A/J mice were painted topically with N-nitroso-tris-chloroethylurea (NTCU) for induction of pLSCC, and the histopathological and molecular characteristics of NTCU-induced lung lesions were examined. Histopathologically, we found atypical bronchiolar hyperplasia, squamous metaplasia, squamous dysplasia, and pLSCCs in the treated mice. Furthermore, we identified deltaNp63(pos)CD44v(pos)CK5/6(pos)CC10(pos) clara cells as key constituents of early precancerous atypical bronchiolar hyperplasia. In addition, deltaNp63(pos)CD44v(pos) cells existed throughout the atypical bronchiolar hyperplasias, squamous metaplasias, squamous dysplasias, and pLSCCs. Overall, our findings suggest that NTCU induces pLSCC through an atypical bronchiolar hyperplasia-metaplasia-dysplasia-SCC sequence in mouse lung bronchioles. Notably, Ki67-positive deltaNp63(pos)CD44v(pos) cancer cells, cancer cells overexpressing phosphorylated epidermal growth factor receptor and signal transducer and activator of transcription 3, and tumor-associated macrophages were all present in far greater numbers in the peripheral area of the pLSCCs compared with the central area. These findings suggest that deltaNp63(pos)CD44v(pos) clara cells in mouse lung bronchioles might be the origin of the NTCU-induced pLSCCs. Our findings also suggest that tumor-associated macrophages may contribute to creating a tumor microenvironment in the peripheral area of pLSCCs that allows deltaNp63(pos)CD44v(pos) cancer cell expansion through activation of epidermal growth factor receptor signaling, and that exerts an immunosuppressive effect through activation of signal transducer and activator of transcription 3 signaling.

Novel medium-term carcinogenesis model for lung squamous cell carcinoma induced by N-nitroso-tris-chloroethylurea in mice.

Targeted treatments for lung cancer based on pathological diagnoses are required to enhance therapeutic efficacy. There are few well-established animal models for lung squamous cell carcinoma although several highly reproducible mouse models for lung adenoma and adenocarcinoma are available. This study was carried out to establish a new lung squamous cell carcinoma mouse model. In the first experiment, female A/J mice were painted topically on back skin twice weekly with 75 µL 0.013 M N-nitroso-tris-chloroethylurea for 2, 4, and 8 weeks (n = 15-20 per group) as initiation of lung lesions, and surviving mice were killed at 18 weeks. In the second experiment, mice were treated as above for 4 weeks and killed at 6, 12, or 18 weeks (n = 3 per group). Lung lobes were subjected to histopathological, immunohistochemical, immunoblotting, and ultrastructural analyses. In the case of treatment for 2, 4, and 8 weeks, incidences of lung squamous cell carcinoma were 25, 54, and 71%, respectively. Cytokeratin 5/6 and epidermal growth factor receptor were clearly expressed in dysplasia and squamous cell carcinoma. Desmosomes and tonofilaments developed in the squamous cell carcinoma. Considering the carcinogenesis model, we conclude that 2 or 4 weeks of N-nitroso-tris-chloroethylurea treatment may be suitable for investigating new chemicals for promotional or suppressive effects on lung squamous cell carcinoma.

Diphenylarsinic acid, a chemical warfare-related neurotoxicant, promotes liver carcinogenesis via activation of aryl hydrocarbon receptor signaling and consequent induction of oxidative DNA damage in rats.

Diphenylarsinic acid (DPAA), a chemical warfare-related neurotoxic organic arsenical, is present in the groundwater and soil in some regions of Japan due to illegal dumping after World War II. Inorganic arsenic is carcinogenic in humans and its organic arsenic metabolites are carcinogenic in animal studies, raising serious concerns about the carcinogenicity of DPAA. However, the carcinogenic potential of DPAA has not yet been evaluated. In the present study we found that DPAA significantly enhanced the development of diethylnitrosamine-induced preneoplastic lesions in the liver in a medium-term rat liver carcinogenesis assay. Evaluation of the expression of cytochrome P450 (CYP) enzymes in the liver revealed that DPAA induced the expression of CYP1B1, but not any other CYP1, CYP2, or CYP3 enzymes, suggesting that CYP1B1 might be the enzyme responsible for the metabolic activation of DPAA. We also found increased oxidative DNA damage, possibly due to elevated CYP1B1 expression. Induction of CYP1B1 has generally been linked with the activation of AhR, and we found that DPAA activates the aryl hydrocarbon receptor (AhR). Importantly, the promotion effect of DPAA was observed only at a dose that activated the AhR, suggesting that activation of AhR and consequent induction of AhR target genes and oxidative DNA damage plays a vital role in the promotion effects of DPAA. The present study provides, for the first time, evidence regarding the carcinogenicity of DPAA and indicates the necessity of comprehensive evaluation of its carcinogenic potential using long-term carcinogenicity studies.

Clinicopathological significance of combined analysis of cytokeratin19 expression and preoperative serum CYFRA21-1 levels in human lung squamous cell carcinoma.

BACKGROUND: To identify a useful biomarker for human lung squamous cell carcinoma (SCC), the expression of cytokeratin19 (CK19) in human SCC tissue was investigated. In addition, we examined the significance of CK19 expression levels by immunostaining and CYFRA21-1 levels in preoperative serum, and their correlation with the clinicopathologic features of human lung SCC. METHODS: To identify proteins in cancerous and non-cancerous tissues for the diagnosis and prognosis of SCC, QSTAR Elite LC-MS/MS was used. Immunostaining for CK19 was classified as either "CK19-strong" or "CK19-weak". Correlations between prognosis and both CK19 expression in tumor tissues and serum concentrations of CYFRA 21-1 were analyzed in 107 cases of lung SCC. RESULTS: The upregulation of CK19 in human squamous cell carcinoma tissues was observed by LCMS/MS. The weak expression of CK19, as determined by immunostaining intensity, was a significant predictor of poorer disease-specific survival (p = 0.032). The prognosis was significantly poorer for patients with weak CK19 immunostaining in tumor tissues and a high serum concentration of CYFRA21-1 compared with the other groups (p = 0.003). CONCLUSIONS: The combination of weak CK19 expression and high serum CYFRA21-1 levels is a predictor of poorer prognosis for patients with human lung SCC.

Evaluation of the modifying effect of inhalation of mainstream cigarette smoke on mouse bladder carcinogenesis.

Cigarette smoking is one of the major risk factors of bladder cancer in humans. To date, however, there is no experimental evidence for the effects of inhalation exposure to mainstream cigarette smoke on bladder carcinogenesis. The purpose of the present study was to evaluate the effect of inhalation of mainstream cigarette smoke on mouse bladder carcinogenesis using a cigarette smoke inhalation exposure system. Six-week-old male C57BL mice were administered 0.025% N-butyl-N-(4-hydroxybutyl) nitrosamine (BBN) in their drinking water for 8 weeks and then divided into 2 groups and exposed to 0 or 300 mg/m(3) wet total particulate matter mainstream cigarette smoke for 2 h per day, five times per week, for 22 weeks. The incidences of bladder tumors (papilloma and urothelial carcinoma) tended to increase in the cigarette smoke-exposed group (25.0%) compared with the controls (15.8%), albeit without a statistically significant difference. We also evaluated mRNA expression levels of cytochrome P450 (cyp) enzymes and proliferating cell nuclear antigen (PCNA) in the bladder epithelium. Expression of cyp1a1 was significantly increased in the cigarette smoke-exposed group. Cigarette smoke exposure did not have a significant effect on the expression of cyp1a2, cyp 1b1, cyp 2a4, cyp 2b10, cyp 2e1, or PCNA. In conclusion, limited exposure to mainstream cigarette smoke for 22 weeks, caused a significant increase in cyp1a1 expression. This increase coupled with the nonsignificant increase in bladder tumors suggests that a longer period of exposure is required to clarify the effects of cigarette smoke on bladder carcinogenesis.

Carcinogenicity and testicular toxicity of 2-bromopropane in a 26-week inhalation study using the rasH2 mouse model.

2-Bromopropane (2-BP) is a colorless liquid at room temperature and is used in closed systems in factories, mainly as an intermediate for medicines, pesticides, and other chemicals. However, the carcinogenicity of 2-BP is still unknown. The CByB6F1-Tg(HRAS)2Jic (rasH2) transgenic mouse model has been established as an alternative to long-term studies (1.5 years-lifetime) to detect carcinogenicity in as short a time as six months. We performed a 26-week inhalation exposure study of 2-BP using the rasH2 mouse model. Male and female rasH2 mice were exposed to 0, 67, 200, or 600 ppm of 2-BP for 6 h/day, 5 days/week for 26 weeks. All tissues and blood were collected and subjected to biological and histopathological analyses. The results showed a concentration-dependent increase in lung tumor development in male and female rasH2 mice exposed by inhalation to 2-BP, which was significant by Peto's and Poly-3 trend tests. Furthermore, in male rasH2 mice, 2-BP was found to be a testicular toxin. This study is the first to demonstrate that 2-BP is carcinogenic in male and female mice and a testicular toxin in male mice using the rasH2 mouse model.

Respiratory disease in workers handling cross-linked water-soluble acrylic acid polymer.

Eight workers involved in packing cross-linked water-soluble acrylic acid polymer, an organic substance, developed pulmonary fibrosis, and the upper lobe was the most affected. The dust concentration in the polymer packing workstation was measured. Chest computed tomography (CT) was obtained for 82 individuals, including the 8 workers mentioned above. Three workers were histopathologically examined. In six of these eight workers, central pulmonary fibrosis and secondary bulla formation caused pneumothorax. Histopathologically, multiple centrilobular fibrotic foci were observed. Chest CT revealed centrilobular nodular opacity and interlobular septal thickening, suggesting early lesions in the workers because the dust concentration was remarkably high. Although the pathogenesis of the disease is unclear, we reported the occurrence of pulmonary fibrosis caused by the exposure to cross-linked water-soluble acrylic acid polymers in humans as it has not been reported earlier.

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

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

DDX39 acts as a suppressor of invasion for bladder cancer.

The object of the present study was to identify markers for predicting urinary bladder cancer progression by comparative proteome analysis of bladder cancers and paired normal mucosas. We found that DDX39 was overexpressed in four of six bladder cancers examined compared with respective control tissues. Immunohistochemical analysis using 303 bladder cancer specimens revealed that DDX39 was inversely correlated to pT stage and histological grade progression. The incidence of DDX39(high) tumors (positive cells ≥50%) was 68.6%, 43.5%, 20.0%, and 5.3% in pTa, pT1, pTis, and ≥pT2 tumors, respectively, and 65.2%, 60.7%, and 19.6% in G1, G2, and G3 tumors, respectively. The incidence of DDX39(high) tumors was significantly lower in pT1 and ≥pT2 compared to pTa tumors, and also significantly lower in G3 compared to G1 and G2 tumors. Follow-up analysis (n = 105) revealed that DDX39(low) tumors (positive cells <50%) were associated with disease progression (hazard ratio 7.485; P = 0.0083). Furthermore, DDX39-knockdown bladder cancer cells increased their invasion ability compared to negative control cells. These results suggest that DDX39 is a suppressor of invasion and loss of its function predicts disease progression in bladder cancers.