Tumor Stroma as a Therapeutic Target for Pancreatic Ductal Adenocarcinoma.

Pancreatic ductal adenocarcinoma (PDAC) has a poor prognosis owing to its desmoplastic stroma. Therefore, therapeutic strategies targeting this tumor stroma should be developed. In this study, we describe the heterogeneity of cancer-associated fibroblasts (CAFs) and their diverse roles in the progression, immune evasion, and resistance to treatment of PDAC. We subclassified the spatial distribution and functional activity of CAFs to highlight their effects on prognosis and drug delivery. Extracellular matrix components such as collagen and hyaluronan are described for their roles in tumor behavior and treatment outcomes, implying their potential as therapeutic targets. We also discussed the roles of extracellular matrix (ECM) including matrix metalloproteinases and tissue inhibitors in PDAC progression. Finally, we explored the role of the adaptive and innate immune systems in shaping the PDAC microenvironment and potential therapeutic strategies, with a focus on immune cell subsets, cytokines, and immunosuppressive mechanisms. These insights provide a comprehensive understanding of PDAC and pave the way for the development of prognostic markers and therapeutic interventions.

Vactosertib, TGF-ß receptor I inhibitor, augments the sensitization of the anti-cancer activity of gemcitabine in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) exhibits a pronounced extracellular matrix (ECM)-rich response, which is produced by an excessive amount of transforming growth factor ß (TGF-ß), resulting in tumor progression and metastasis. In addition, TGF-ß signaling contributes to rapidly acquired resistance and incomplete response to gemcitabine. Recently, selective inhibitors of the TGF-ß signaling pathway have shown promise in PDAC treatment, particularly as an option for augmenting responses to chemotherapy. Here, we investigated the synergistic anticancer effects of a small-molecule TGF-ß receptor I kinase inhibitor (vactosertib/EW-7197) in the presence of gemcitabine, and its mechanism of action in pancreatic cancer. Vactosertib sensitized pancreatic cancer cells to gemcitabine by synergistically inhibiting their viability. Importantly, the combination of vactosertib and gemcitabine significantly attenuated the expression of major ECM components, including collagens, fibronectin, and α-SMA, in pancreatic cancer compared with gemcitabine alone. This resulted in potent induction of mitochondrial-mediated apoptosis, gemcitabine-mediated cytotoxicity, and inhibition of tumor ECM by vactosertib. Additionally, the combination decreased metastasis through inhibition of migration and invasion, and exhibited synergistic anti-cancer activity by inhibiting the TGF-ß/Smad2 pathway in pancreatic cancer cells. Furthermore, co-treatment significantly suppressed tumor growth in orthotopic models. Therefore, our findings demonstrate that vactosertib synergistically increased the antitumor activity of gemcitabine via inhibition of ECM component production by inhibiting the TGF-ß/Smad2 signaling pathway. This suggests that the combination of vactosertib and gemcitabine may be a potential treatment option for patients with pancreatic cancer.

A novel DDR1 inhibitor enhances the anticancer activity of gemcitabine in pancreatic cancer.

Pancreatic ductal adenocarcinoma (PDAC) is an extracellular matrix (ECM)-rich carcinoma, which promotes chemoresistance by inhibiting drug diffusion into the tumor. Discoidin domain receptor 1 (DDR1) increases tumor progression and drug resistance by binding to collagen, a major component of tumor ECM. Therefore, DDR1 inhibition may be helpful in cancer therapeutics by increasing drug delivery efficiency and improving drug sensitivity. In this study, we developed a novel DDR1 inhibitor, KI-301690 and investigated whether it could improve the anticancer activity of gemcitabine, a cytotoxic agent widely used for the treatment of pancreatic cancer. KI-301690 synergized with gemcitabine to suppress the growth of pancreatic cancer cells. Importantly, its combination significantly attenuated the expression of major tumor ECM components including collagen, fibronectin, and vimentin compared to gemcitabine alone. Additionally, this combination effectively decreased mitochondrial membrane potential (MMP), thereby inducing apoptosis. Further, the combination synergistically inhibited cell migration and invasion. The enhanced anticancer efficacy of the co-treatment could be explained by the inhibition of DDR1/PYK2/FAK signaling, which significantly reduced tumor growth in a pancreatic xenograft model. Our results demonstrate that KI-301690 can inhibit aberrant ECM expression by DDR1/PYK2/FAK signaling pathway blockade and attenuation of ECM-induced chemoresistance observed in desmoplastic pancreatic tumors, resulting in enhanced antitumor effect through effective induction of gemcitabine apoptosis.

Lidocaine enhances the efficacy of palbociclib in triple-negative breast cancer.

The use of anesthetics in the surgical resection of tumors may influence the prognosis of cancer patients. Lidocaine, a local anesthetic, is known to act as a chemosensitizer and relieve pain in some cancers. In addition, palbociclib, a potent cyclin-dependent kinase (CDK) 4/6 inhibitor, has been approved for chemotherapy of advanced breast cancer. However, recent studies have revealed the acquired resistance of breast cancer cells to palbociclib. Therefore, the development of combination therapies that can extend the efficacy of palbociclib or delay resistance is crucial. This study investigated whether lidocaine would enhance the efficacy of palbociclib in breast cancer. Lidocaine synergistically suppressed the growth and proliferation of breast cancer cells by palbociclib. The combination treatment showed an increased cell cycle arrest in the G0/G1 phase by decreasing retinoblastoma protein (Rb) and E2F1 expression. In addition, it increased apoptosis by loss of mitochondrial membrane potential as observed by increases in cytochrome c release and inhibition of mitochondria-mediated protein expression. Additionally, it significantly reduced epithelial-mesenchymal transition and PI3K/AKT/GSK3ß signaling. In orthotopic breast cancer models, this combination treatment significantly inhibited tumor growth and increased tumor cell apoptosis compared to those treated with a single drug. Taken together, this study demonstrates that the combination of palbociclib and lidocaine has a synergistic anti-cancer effect on breast cancer cells by the inhibition of the PI3K/AKT/GSK3ß pathway, suggesting that this combination could potentially be an effective therapy for breast cancer.

Discovery of a novel NUAK1 inhibitor against pancreatic cancer.

The novel (nua) kinase family 1 (NUAK1) is an AMPK-related kinase and its expression is associated with tumor malignancy and poor prognosis in several types of cancer, suggesting its potential as a target for cancer therapy. Therefore, the development of NUAK1-targeting inhibitors could improve therapeutic outcomes in cancer. We synthesized KI-301670, a novel NUAK1 inhibitor, and assessed its anticancer effects and mechanism of action in pancreatic cancer. It effectively inhibited pancreatic cancer growth and proliferation, and induced cell cycle arrest, markedly G0/G1 arrest, by increasing the expression of p27 and decreasing expression of p-Rb and E2F1. Additionally, the apoptotic effect of KI-301670 was observed by an increase in cleaved PARP, TUNEL-positive cells, and annexin V cell population, as well as the release of cytochrome c via the loss of mitochondrial membrane potential. KI-301670 inhibited the migration and invasion of pancreatic cancer cells. Mechanistically, KI-301670 effectively inhibited the PI3K/AKT pathway in pancreatic cancer cells. Furthermore, it significantly attenuated tumor growth in a mouse xenograft tumor model. Our results demonstrate that a novel NUAK1 inhibitor, KI-301670, exerts anti-tumor effects by directly suppressing cancer cell growth by affecting the PI3K/AKT pathway, suggesting that it could be a novel therapeutic candidate for pancreatic cancer treatment.

Classification of Mouse Lung Metastatic Tumor with Deep Learning.

Traditionally, pathologists microscopically examine tissue sections to detect pathological lesions; the many slides that must be evaluated impose severe work burdens. Also, diagnostic accuracy varies by pathologist training and experience; better diagnostic tools are required. Given the rapid development of computer vision, automated deep learning is now used to classify microscopic images, including medical images. Here, we used a Inception-v3 deep learning model to detect mouse lung metastatic tumors via whole slide imaging (WSI); we cropped the images to 151 by 151 pixels. The images were divided into training (53.8%) and test (46.2%) sets (21,017 and 18,016 images, respectively). When images from lung tissue containing tumor tissues were evaluated, the model accuracy was 98.76%. When images from normal lung tissue were evaluated, the model accuracy ("no tumor") was 99.87%. Thus, the deep learning model distinguished metastatic lesions from normal lung tissue. Our approach will allow the rapid and accurate analysis of various tissues.

Human Placenta Hydrolysate Promotes Liver Regeneration via Activation of the Cytokine/Growth Factor-Mediated Pathway and Anti-oxidative Effect.

Liver regeneration is a very complex process and is regulated by several cytokines and growth factors. It is also known that liver transplantation and the regeneration process cause massive oxidative stress, which interferes with liver regeneration. The placenta is known to contain various physiologically active ingredients such as cytokines, growth factors, and amino acids. In particular, human placenta hydrolysate (hPH) has been found to contain many amino acids. Most of the growth factors found in the placenta are known to be closely related to liver regeneration. Therefore, in this study, we investigated whether hPH is effective in promoting liver regeneration in rats undergoing partial hepatectomy. We confirmed that cell proliferation was significantly increased in HepG2 and human primary cells. Hepatocyte proliferation was also promoted in partial hepatectomized rats by hPH treatment. hPH increased liver regeneration rate, double nucleic cell ratio, mitotic cell ratio, proliferating cell nuclear antigen (PCNA), and Ki-67 positive cells in vivo as well as interleukin (IL)-6, tumor necrosis factor alpha (TNF-α), and hepatocyte growth factor (HGF). Moreover, Kupffer cells secreting IL-6 and TNF-α were activated by hPH treatment. In addition, hPH reduced thiobarbituric acid reactive substances (TBARs) and significantly increased glutathione (GSH), glutathione peroxidase (GPx), and superoxide dismutase (SOD). Taken together, these results suggest that hPH promotes liver regeneration by activating cytokines and growth factors associated with liver regeneration and eliminating oxidative stress.

A 13-week repeated-dose oral toxicity and bioaccumulation of aluminum oxide nanoparticles in mice.

Because of an increase in the commercial applications of manufactured nanoparticles, the issue of potential adverse health effects of nanoparticles following intended or unintended exposure is rapidly gaining attention. In this study, we evaluated the toxicity of aluminum oxide nanoparticles (AlNPs, rod-type, 1.5, 3, and 6 mg/kg) after oral administration to mice for 13 weeks. Compared with the control group, the consumption of diet and drinking water and body weight gain decreased in the group treated with AlNPs. The group treated with 6 mg/kg AlNPs also showed a marked elevation in the count of white blood cells that associated with a significant decrease and increase to the proportion of eosinophils and lymphocytes, respectively. In addition, the secretion of IL-6 and monocyte chemotactic protein-1 increased in a dose-dependent manner in the treated groups. Furthermore, AlNPs showed the highest accumulation in the liver and kidneys compared with the control group, increased the lactate dehydrogenase level in the blood, and induced the development of a pathological lesion in the liver and kidneys. Taken together, we suggest that the target organs of rod-type AlNPs may be the liver, kidneys and the immune system, and the not-observed adverse effect level may be lower than 6 mg/kg.

Toxic response of graphene nanoplatelets in vivo and in vitro.

With the development of nanotechnology, myriad types of novel materials have been discovered at the nanoscale, among which the most interesting material is graphene. However, the toxicity data available on graphene are extremely limited. In this study, we explored toxic response of commercially available graphene nanoplatelets (GNPs) in vivo and in vitro. The GNPs used in this study had a high surface area and feature considerably few defects. In mice, GNPs (2.5 and 5 mg/kg) remained in the lung until 28 days after a single instillation, and the secretion of inflammatory cytokines reached the maximal level at Day 14 and then decreased over time. In vitro study using BEAS-2B cells, a human bronchial epithelial cell line, GNPs located within autophagosome-like vacuoles 24 h after exposure. The GNPs (2.5, 5, 10, and 20 µg/mL) also dose-dependently reduced cell viability, which was accompanied by an increase in the portion of cells in the subG1 and S phases. Moreover, the GNPs down-regulated the generation of reactive oxygen species, suppressed ATP production, caused mitochondria damage, and elevated the levels of autophagy-related proteins. Based on these results, we suggest that GNPs provoked a subchronic inflammatory response in mice and that GNPs induced autophagy accompanying apoptosis via mitochondria damage in vitro.

Subchronic oral toxicity of evodia fruit powder in rats.

ETHNOPHARMACOLOGICAL RELEVANCE: Evodia, a fruit from Evodia rutaecarpa, has been used in oriental medicine, and since its various pharmaceutical actions, including anti-cancer activity, have become known, evodia has been widely used as a dietary supplement. However, information regarding its toxicity is limited. MATERIALS AND METHODS: Evodia fruit from Evodia rutaecarpa (Juss.) Benth. var. officinalis (Dode) Huang (0, 25, 74, 222, 667, and 2000 mg/kg) was administered orally five times per week for 13 weeks. Clinical signs, body weight, food consumption, hematology, serum chemistry, urinalysis, vaginal cytology, sperm morphology, organ weight, and gross and histopathological findings were evaluated. RESULTS: Urinary ketone body excretion was detected in males at 667 and 2000 mg/kg and in females at 2000 mg/kg. An increase in absolute/relative liver weight was observed in both sexes at 2000 mg/kg. Although levels of serum alanine aminotransferase, glucose, total cholesterol, and triglycerides were significantly reduced in males and/or females at 200 and/or 667 and 2000 mg/kg, all values were within normal ranges and were considered non-adverse. In addition, no treatment-related differences in body weight, food consumption, hematology, vaginal cytology, sperm morphology, or gross and histopathological examination were detected. CONCLUSIONS: The subchronic no-observable-adverse-effect level for evodia fruit powder following oral administration in rats is greater than 2000 mg/kg.

Modifying effect of diallyl sulfide on colon carcinogenesis in C57BL/6J-ApcMin/⁺ mice.

Diallyl sulfide (DAS), a flavoring compound derived from garlic, is considered to have cancer chemopreventive potential in experimental animals and humans. This study was designated to examine possible chemopreventive effects of DAS on colon carcinogenesis using genetically engineered transgenic ApcMin/⁺ mice, a well-established animal model for familial adenomatous polyposis (FAP) and sporadic colorectal cancer. Male C57BL/6J-ApcMin/⁺ mice were divided into three groups. Animals of group 1 were placed on the basal diet (AIN-76A) as non-treated controls. Animals of groups 2 and 3 were given DAS- containing diets (in doses of 100 and 300 ppm, respectively). All mice were sacrificed at the end of week 10 of the experiment. Histopathological investigation revealed that the incidence of colonic polyps was decreased dose-dependently by 19% (13/16) in group 2 and by 32% (13/20) in group 3 compared to the 100% incidence (10/10) in group 1. The multiplicity of colonic polyps per mouse was also slightly decreased by DAS treatment (1.88 ± 0.35 in group 2 and 1.63 ± 0.36 in group 3) compared to 2.00 ± 0.39 in group 1. On the other hand, there were no significant differences in the numbers of total polyps per mouse in the small intestine between the groups. Taken together, we suggest that DAS may exert promising inhibitory effects on colon carcinogenesis in the transgenic ApcMin/⁺ mice.

26-Week carcinogenicity study of di-isodecyl phthalate by dietary administration to CB6F1-rasH2 transgenic mice.

This study examined the carcinogenic potential of di-isodecyl phthalate (DIDP) in rasH2 mice. DIDP was administered to 15 rasH2 mice/gender/group at dietary levels of 0, 0.1, 0.33, or 1% and 15 wild-type mice/gender/group at dietary levels of 0 and 1% for 26 weeks. Non-neoplastic changes were observed in the liver (parenchymal inflammation, fatty changes, diffuse hepatocyte hypertrophy with eosinophilic granules and focal necrosis) and kidneys (tubular basophilia and tubular hyperplasia) after administration of DIDP in the rasH2 and wild-type mice. In the neoplastic lesions, there were a higher number of hepatocellular adenomas in the male rasH2 mice receiving 1% DIDP, compared with the findings in the liver of control rasH2 mice or wild-type mice. The incidence of hepatocellular adenomas in the 0.1, 0.33, and 1% DIDP exposed rasH2 mice was 7% (1/15), 7% (1/15), and 33% (5/15), respectively. This study adds a set of results for an additional test chemical for the performance of the rasH2 short-term transgenic model to the existing database of 3 compounds (WY-14643, DEHP, and clofibrate) tested in the ILSI/HESI ACT project.

Spontaneous multicentric malignant schwannoma in a male Fischer 344 rat.

We describe here a multicentric spontaneous malignant schwannoma obtained from one male F344 rat, and this animal was the subject of a carcinogenicity study for which it was treated with diisodecyl phthalate. The animal of the control group not treated with diisodecyl phthalate showed dyspnea and severe lordosis. On the necropsy, two tan, firm, encapsulated masses were observed in the subcutis of the lumbosacral region and the left inguinal region of the abdominal cavity, respectively; the masses were 25 × 17 × 8 mm and 16 × 14 × 8 mm in size, respectively. Histologically, the tumor consisted of spindle and pleomorphic cells that grew in various patterns, that was, sweeping fascicles and herringbone and local organoid patterns. The pleomorphic neoplastic cells had more than two nuclei. Additionally, the diagnosis of malignant schwannoma was confirmed by the immune reactivity of the tumor cells for S-100 protein.

Decreased Diethylnitrosamine-induced Liver Preneoplastic Lesions by Estradiol-3-benzoate Treatment.

To clarify whether inhibitory effect of estrogen on liver tumor is associated with cell proliferation, we investigated its role in diethylnitrosamine (DEN)-induced rat preneoplastic lesions, with time sequenced manners. F344 male rats (n = 90) were divided into three groups at 5 weeks of age. The mini-osmotic pumps providing a continuous infusion of DEN was implanted into the abdominal cavity of each animal in group 1, 2 and 3 at 6 weeks of age. To see the effect of estrogen, pellet containing 1 or 10 µg of estradiol- 3-benzoate (EB) was implanted subcutaneously in the animals of groups 2 or 3, respectively, one week prior to DEN treatment. Ten animals of each group were euthanized at 10, 14 and 18 weeks after DEN treatment. Liver tissues at each time point were fixed in 10% phosphate-buffered formalin and were processed and embedded in paraffin and 5 µm sections mounted on a silanized slide. Glutathione S-transferase placental form (GST-P) positive foci and 5-bromo-2-deoxyuridine (BrdU) labeling cells were detected at each time point. Area of GST-P positive foci in DEN+EB 1 or 10 µg group was significantly decreased compared to DEN alone at 14 weeks (p < 0.01 or p < 0.05, respectively) an at 18 weeks (p < 0.05 or p < 0.01, respectively). BrdU index in DEN+EB 1 or 10 µg groups was significantly decreased compared to DEN alone at 14 weeks and at 18 weeks (p < 0.01). Taken together, we conclude that EB treatment decrease the DEN-induced liver preneoplastic lesions and this may be associated with decrease of cellular proliferation.

Chitosan nanoparticles show rapid extrapulmonary tissue distribution and excretion with mild pulmonary inflammation to mice.

Pulmonary delivery of nanoparticles (NP) conjugated with therapeutic agents has been considered recently for both lung disorders and systemic circulation. Hydrophobically modified glycol chitosan (HGC) NP have previously shown excellent deposition to the tumor site and non-destructive intracellular release. Here, we evaluated the kinetics and toxicity of HGC NP by intratracheal instillation to mice. HGC NP showed a positive charge and average hydrodynamic size was around 350 nm. The half-life of NP in the lung was determined as 131.97±50.51 h. NP showed rapid uptake into systemic circulation and excretion via urine which was peaked at 6h after instillation. Although HGC NP were distributed to several extrapulmonary organs, the levels were extremely low and transient. HGC NP induced transient neutrophilic pulmonary inflammation from 6h to day 3 after instillation. Expression of pro-inflammatory cytokines (IL-1ß, IL-6, and TNF-α) and chemokine (MIP-1α) in lung showed an increase from 1h to 24h after instillation and recovered thereafter. Our findings suggest that HGC NP can be successful candidates for use as pulmonary delivery vehicles, owing to their excellent biocompatibility, transiency, and low pulmonary toxicity, and property of rapid elimination without accumulation.

Carcinogenicity study of 3-monochloropropane-1, 2-diol (3-MCPD) administered by drinking water to B6C3F1 mice showed no carcinogenic potential.

3-Monochloropropane-1, 2-diol (or 3-chloro-1,2-propanediol, 3-MCPD) is a well-known food processing contaminant found in a wide range of foods and ingredients. It has been classified as non-genotoxic carcinogen but its carcinogenic potential in the rodents has been controversial. The carcinogenicity to B6C3F1 mice by drinking water administration was assessed over a period of 104 weeks. Three groups, each comprising 50 male and 50 female mice received 3-MCPD at dosages of 30, 100 or 300 ppm up to Day 100 and 200 ppm onward (4.2, 14.3 and 33.0 mg/kg for males; 3.7, 12.2, and 31.0 mg/kg for females), were allocated. Survival was good, with at least 80% of males and 72% of females in each group surviving 104 weeks. Body weights and body weight gain were decreased in males and females receiving 200 ppm. Water and food consumptions of both sexes at 300/200 ppm were lowered. Emaciated or crouching position was observed for animals of both sexes exposed to 200 ppm. There were some differences in hematology and serum biochemistry compared with controls, although there was no histopathological evidence to support those changes. Histopathological examination did not reveal any neoplastic or non-neoplastic findings attributable to treatment with 3-MCPD. It is concluded that drinking water administration of 3-MCPD for 104 weeks revealed no evidence of carcinogenic potential.

Comparison of gene expression profiles in mice liver following intravenous injection of 4 and 100 nm-sized PEG-coated gold nanoparticles.

Gold nanoparticles (AuNPs) have been widely used in various biomedical applications for photothermal therapy, imaging and drug delivery. Although AuNPs have been recognized as a biologically safe material, very little is known about their molecular and cellular effects. To evaluate the gene expression profile and mechanism of the molecular level of polyethylene glycol (PEG)-coated AuNPs and the effect of particle size, we applied an expression profiling approach. PEG-coated AuNPs of different particle sizes, 4 and 100 nm, were intravenously administered to BALB/c mice (4.26 mg/kg, body weight). Thirty minutes after injection of AuNPs, the mice were sacrificed and liver tissues were removed. Then, pathological examination and microarray analysis were performed on the liver tissues. Histology of the liver tissues did not indicate any pathological changes in all treatment groups. Only 0.38% (170 genes) and 0.50% (224 genes) of the total genes (45,000 genes) were significantly induced by the treatment of 4 or 100 nm AuNPs, respectively. In addition, the 4 and 100 nm AuNPs treatment groups shared 67.1% and 50.9% of the significantly changed genes, respectively. Commonly expressed genes by a single intravenous injection of 4 or 100 nm AuNPs were categorized as apoptosis, cell cycle, inflammation, and metabolic process. In the specifically expressed genes of 4 or 100 nm AuNPs, although the genes were different each other, 4 and 100 nm AuNPs showed similar gene categories such as cell cycle, response to stress, signal transduction, and metabolic process. Therefore, we can conclude that 4 and 100 nm AuNPs showed similar biological effects on liver tissues of mice.

Pulmonary toxicity and kinetic study of Cy5.5-conjugated superparamagnetic iron oxide nanoparticles by optical imaging.

Recent advances in the development of nanotechnology and devices now make it possible to accurately deliver drugs or genes to the lung. Magnetic nanoparticles can be used as contrast agents, thermal therapy for cancer, and be made to concentrate to target sites through an external magnetic field. However, these advantages may also become problematic when taking into account safety and toxicological factors. This study demonstrated the pulmonary toxicity and kinetic profile of anti-biofouling polymer coated, Cy5.5-conjugated thermally cross-linked superparamagnetic iron oxide nanoparticles (TCL-SPION) by optical imaging. Negatively charged, 36 nm-sized, Cy5.5-conjugated TCL-SPION was prepared for optical imaging probe. Cy5.5-conjugated TCL-SPION was intratracheally instilled into the lung by a non-surgical method. Cy5.5-conjugated TCL-SPION slightly induced pulmonary inflammation. The instilled nanoparticles were distributed mainly in the lung and excreted in the urine via glomerular filtration. Urinary excretion was peaked at 3 h after instillation. No toxicity was found under the concentration of 1.8 mg/kg and the half-lives of nanoparticles in the lung and urine were estimated to be about 14.4+/-0.54 h and 24.7+/-1.02 h, respectively. Although further studies are required, our results showed that Cy5.5-conjugated TCL-SPION can be a good candidate for use in pulmonary delivery vehicles and diagnostic probes.

Subchronic inhalation toxicity of silver nanoparticles.

The subchronic inhalation toxicity of silver nanoparticles was studied in Sprague-Dawley rats. Eight-week-old rats, weighing approximately 253.2 g (males) and 162.6 g (females), were divided into four groups (10 rats in each group): fresh-air control, low dose (0.6 x 10(6) particle/cm(3), 49 microg/m(3)), middle dose (1.4 x 10(6) particle/cm(3), 133 microg/m(3)), and high dose (3.0 x 10(6) particle/cm(3), 515 microg/m(3)). The animals were exposed to silver nanoparticles (average diameter 18-19 nm) for 6 h/day, 5 days/week, for 13 weeks in a whole-body inhalation chamber. In addition to mortality and clinical observations, body weight, food consumption, and pulmonary function tests were recorded weekly. At the end of the study, the rats were subjected to a full necropsy, blood samples were collected for hematology and clinical chemistry tests, and the organ weights were measured. Bile-duct hyperplasia in the liver increased dose dependently in both the male and female rats. Histopathological examinations indicated dose-dependent increases in lesions related to silver nanoparticle exposure, including mixed inflammatory cell infiltrate, chronic alveolar inflammation, and small granulomatous lesions. Target organs for silver nanoparticles were considered to be the lungs and liver in the male and female rats. No observable adverse effect level of 100 microg/m(3) is suggested from the experiments.

Carcinogenicity study of 3-monochloropropane-1,2-diol in Sprague-Dawley rats.

3-Monochloropropane-1,2-diol (alpha-chlorohydrin, 3-MCPD) is a well-known contaminant, which has been detected in a wide range of foods and ingredients, and is also a suspected cause of cancer. In this study, the carcinogenicity of 3-MCPD in SD rats was investigated. Groups of 50 male and 50 female rats were exposed for two years to drinking water containing 0, 25, 100 or 400ppm 3-MCPD. The body weights and water consumptions of the male and female rats given 400ppm 3-MCPD were significantly lower than those of the controls. The incidences of renal tubule adenomas or carcinomas and Leydig cell tumors occurred with dose-related positive trends in male rats. The incidences of renal tubule carcinomas and Leydig cell tumors were significantly increased in male rats given 400ppm 3-MCPD. The incidence of renal tubule adenomas showed a positive trend in female rats, which was significant in 400ppm 3-MCPD group. In conclusion, there was clear evidence of the carcinogenic activity of 3-MCPD in male SD rats, based on the increased incidences of renal tubule carcinomas and Leydig cell tumors. There was some evidence of the carcinogenic activity of 3-MCPD in female SD rats, based on the increased incidence of renal tubule adenomas.