Actin nucleoskeleton in embryonic development and cellular differentiation.

Dynamic assembly and disassembly of actin proteins play a key role in the cytoskeleton, but the cellular functions of actin are not only restricted to the cytoplasmic compartment. Recent studies have shown that actin spatiotemporally changes its polymerized state in the nucleus as well and such dynamic nature of actin is relevant to key nuclear events including gene expression, DNA damage response and chromatin organization. In this review, we highlight emerging roles of actin in the nuclear compartment especially in the context of embryonic development and cellular differentiation. We first explain how the actin nucleoskeleton can be formed and function in cells. Notably, nuclear actin dynamics are greatly altered when cell fates change, such as after fertilization and T cell differentiation. We discuss how the dynamic actin nucleoskeleton contributes to accomplishing developmental programs.

Assessment of the toxicity and carcinogenicity of double-walled carbon nanotubes in the rat lung after intratracheal instillation: a two-year study.

BACKGROUND: Considering the expanding industrial applications of carbon nanotubes (CNTs), safety assessment of these materials is far less than needed. Very few long-term in vivo studies have been carried out. This is the first 2-year in vivo study to assess the effects of double walled carbon nanotubes (DWCNTs) in the lung and pleura of rats after pulmonary exposure. METHODS: Rats were divided into six groups: untreated, Vehicle, 3 DWCNT groups (0.12 mg/rat, 0.25 mg/rat and 0.5 mg/rat), and MWCNT-7 (0.5 mg/rat). The test materials were administrated by intratracheal-intrapulmonary spraying (TIPS) every other day for 15 days. Rats were observed without further treatment until sacrifice. RESULTS: DWCNT were biopersistent in the rat lung and induced marked pulmonary inflammation with a significant increase in macrophage count and levels of the chemotactic cytokines CCL2 and CCL3. In addition, the 0.5 mg DWCNT treated rats had significantly higher pulmonary collagen deposition compared to the vehicle controls. The development of carcinomas in the lungs of rats treated with 0.5 mg DWCNT (4/24) was not quite statistically higher (p = 0.0502) than the vehicle control group (0/25), however, the overall incidence of lung tumor development, bronchiolo-alveolar adenoma and bronchiolo-alveolar carcinoma combined, in the lungs of rats treated with 0.5 mg DWCNT (7/24) was statistically higher (p < 0.05) than the vehicle control group (1/25). Notably, two of the rats treated with DWCNT, one in the 0.25 mg group and one in the 0.5 mg group, developed pleural mesotheliomas. However, both of these lesions developed in the visceral pleura, and unlike the rats administered MWCNT-7, rats administered DWCNT did not have elevated levels of HMGB1 in their pleural lavage fluids. This indicates that the mechanism by which the mesotheliomas that developed in the DWCNT treated rats is not relevant to humans. CONCLUSIONS: Our results demonstrate that the DWCNT fibers we tested are biopersistent in the rat lung and induce chronic inflammation. Rats treated with 0.5 mg DWCNT developed pleural fibrosis and lung tumors. These findings demonstrate that the possibility that at least some types of DWCNTs are fibrogenic and tumorigenic cannot be ignored.

Effects of oral bovine lactoferrin on a mouse model of inflammation associated colon cancer.

Patients with ulcerative colitis or colonic Crohn's disease have a significantly increased risk of developing colorectal cancer. Bovine lactoferrin (bLF) reportedly inhibited the development of colon cancer in rats and mice, and in a placebo controlled trial, ingestion of bLF inhibited the growth of intestinal polyps. In addition, in a case study, a patient with Crohn's disease was reported to have remained in remission for over 7 years while ingesting 1 g of bLF daily. Thus, bLF has an inhibitory effect on colon carcinogenesis, and it may also promote remission of Crohn's disease. The purpose of this study was to investigate the effects of bLF in a mouse model of colorectal cancer related to irritable bowel disease (IBD). The mice were divided into 4 groups: (i) no treatment; (ii) treated with bLF only; (iii) treated with azoxymethane plus dextran sulfate sodium (AOM + DSS); and (iv) treated with AOM + DSS + bLF. AOM was used to initiate intestinal cancer, and DSS was used to induce IBD-like inflammation in the intestine of the C57BL/6 mice. At the end of the study, the mice treated with AOM + DSS + bLF had a better fecal score, fewer lesions in the colon, and less weight loss than the mice treated with AOM + DSS without bLF. However, there were no statistically significant differences between the two groups with respect to tumor burden.

Comparative carcinogenicity study of a thick, straight-type and a thin, tangled-type multi-walled carbon nanotube administered by intra-tracheal instillation in the rat.

BACKGROUND: Multi-walled carbon nanotubes can be divided into two general subtypes: tangled and straight. MWCNT-N (60 nm in diameter) and MWCNT-7 (80-90 nm in diameter) are straight-type MWCNTs, and similarly to asbestos, both are carcinogenic to the lung and pleura when administered to rats via the airway. Injection of straight-type MWCNTs into the peritoneal cavity also induces the development of mesothelioma, however, injection of tangled-type MWCNTs into the peritoneal cavity does not induce carcinogenesis. To investigate these effects in the lung we conducted a 2-year comparative study of the potential carcinogenicities of a straight-type MWCNT, MWCNT-A (approximately 150 nm in diameter), and a tangled-type MWCNT, MWCNT-B (7.4 nm in diameter) after administration into the rat lung. Crocidolite asbestos was used as the reference material, and rats administered vehicle were used as the controls. Test materials were administered by intra-Tracheal Intra-Pulmonary Spraying (TIPS) once a week over a 7 week period (8 administrations from day 1 to day 50), followed by a 2-year observation period without further treatment. Rats were administered total doses of 0.5 or 1.0 mg MWCNT-A and MWCNT-B or 1.0 mg asbestos. RESULTS: There was no difference in survival between any of the groups. The rats administered MWCNT-A or asbestos did not have a significant increase in bronchiolo-alveolar hyperplasia or tumors in the lung. However, the rats administered MWCNT-B did have significantly elevated incidences of bronchiolo-alveolar hyperplasia and tumors in the lung: the incidence of bronchiolo-alveolar hyperplasia was 0/20, 6/20, and 9/20 in the vehicle, 0.5 mg MWCNT-B, and 1.0 mg MWCNT-B groups, respectively, and the incidence of adenoma and adenocarcinoma combined was 1/19, 5/20, and 7/20 in the vehicle, 0.5 mg MWCNT-B, and 1.0 mg MWCNT-B groups, respectively. Malignant pleural mesothelioma was not induced in any of the groups. CONCLUSIONS: The results of this initial study indicate that tangled-type MWCNT-B is carcinogenic to the rat lung when administered via the airway, and that straight-type MWCNT-A did not have higher carcinogenic potential in the rat lung than tangled-type MWCNT-B.

Anti-inflammatory and anticancer effects of p-methoxycinnamic acid, an active phenylpropanoid, against 1,2-dimethylhydrazine-induced rat colon carcinogenesis.

p-methoxycinnamic acid (p-MCA) is an active phenolic acid found in rice bran, turmeric, brown rice, Kaempferia galanga, buckwheat inflorescence, etc. Earlier, we have reported that p-methoxycinnamic acid possesses antioxidant and antilipidperoxidative effects on 1,2-dimethylhyrdrazine (DMH)-induced colon carcinogenesis. The purpose of this study is to unravel the anti-inflammatory and anticancer properties of p-MCA against DMH-induced colon carcinogenesis. Male albino Wistar rats were randomly divided into six groups. Group 1 served as control, group 2 rats received 40 mg/kg b.wt. of p-MCA in 0.1% carboxymethylcellulose (CMC) every day, and colon cancer was induced in groups 3-6 using DMH at the dose of (20 mg/kg b.wt. subcutaneously) once a week for 15 weeks. In addition, along with DMH, groups 4 (initiation), 5 (post initiation) and 6 (entire period) rats received p-MCA (40 mg/kg b.wt.) p.o. every day during different time periods for the total experimental period of 30 weeks. Colon of animals treated with DMH showed an increased number of aberrant crypt foci (ACFs), increased nuclear translocation of transcription factor NF-κB p65 subunit, increased expression of inflammatory markers (iNOS, COX-2), cytokines (tumour necrosis factor-α, interleukin-6), cyclin D1, antiapoptotic protein (Bcl-2), metastasis marker (matrix metalloproteinase-2 (MMP-2)) and angiogenic marker (vascular endothelial growth factor VEGF) and decreased expression of pro-apoptotic proteins (Bax, caspases 3 and 9). On supplementing with p-MCA (40 mg/kg b.wt.) throughout the entire experimental period, DMH-induced pathological alterations reversed significantly to normal.

Biochemical and molecular mechanisms underlying the chemopreventive efficacy of rosmarinic acid in a rat colon cancer.

To shed light on colon cancer chemoprevention, natural phytochemicals attract researchers by virtue of their beneficial biological effects. The chemopreventive potential of rosmarinic acid (RA) was tested by using the colon carcinogen, 1,2-dimethylhydrazine (DMH) by evaluating the Aberrant crypt foci (ACF), tumour incidence, lipid peroxidative byproducts, phase I & II drug metabolizing enzymes, cell proliferative and apoptotic proteins. Rats were divided into six groups and received modified pellet diet. Group 1 served as control rats, group 2 rats received RA (5mg/kg b.w. p.o.), rats in groups 3-6 received DMH (20mg/kg b.w., s.c.) for the first fifteen weeks. In addition to DMH, groups 4-6 received RA at the dose of 5mg/kg b.w. during initiation, post initiation stages and also for the entire study period. DMH treated rats showed an increase in the development of ACF, tumour formation and multiplicity and decrease in lipid peroxidative byproducts. Moreover, it modulates xenobiotic enzymes and reduces the expressions of proapoptotic proteins; increases expressions of anti apoptotic proteins at the end of the study. Supplementation with RA to carcinogen treated rats protected them from the above deleterious effects caused by DMH and thus RA may be used as a potent chemopreventive agent.

p-Methoxycinnamic acid, an active phenylpropanoid induces mitochondrial mediated apoptosis in HCT-116 human colon adenocarcinoma cell line.

Among the eight phytochemicals (dihydrocarveol, sinapic acid, vanillic acid, ethylgallate, myrtenol, transcarveol, p-methoxycinnamic acid, and isoferulic acid) we tested, p-methoxycinnamic acid (p-MCA) [10 µM] showed the most potent in vitro growth inhibition on human colon adenocarcinoma (HCT-116 cells). Antiproliferative activity of p-MCA at 24h was associated with DNA damage, morphological changes and the results were comparable with doxorubicin. p-MCA induced phosphatidylserine translocation, increased the levels of reactive oxygen species (ROS), thiobarbituric acid reactive substances (TBARS), protein carbonyl content (PCC) and decreased enzymic antioxidant status (SOD, CAT, GPx) in HCT-116. p-MCA treatment increased the percentage of apoptotic cells, decreased the mitochondrial membrane potential and triggered cytochrome C release to cytosol. The induction of apoptosis by p-MCA was accompanied by an increase in caspase 3 and caspase 9 activities, increased expression of Bax and decreased expression of Bcl-2. Thus p-MCA induces mitochondria mediated intrinsic pathway of apoptosis in HCT-116 and has potential for treatment and prevention of colon cancer.

Protective effect of p-methoxycinnamic acid, an active phenolic acid against 1,2-dimethylhydrazine-induced colon carcinogenesis: modulating biotransforming bacterial enzymes and xenobiotic metabolizing enzymes.

Objective of the study is to evaluate the modifying potential of p-methoxycinnamic acid (p-MCA), an active rice bran phenolic acid on biotransforming bacterial enzymes and xenobiotic metabolizing enzymes in 1,2-dimethylhydrazine-induced rat colon carcinogenesis. 48 male albino wistar rats were divided into six groups. Group1 (control) received modified pellet diet and 0.1 % carboxymethylcellulose; group2 received modified pellet diet along with p-MCA (80 mg/kg b.wt. p.o.) everyday for 16 weeks; groups 3-6 received 1,2-dimethylhydrazine (DMH) (20 mg/kg b.wt.) subcutaneous injection once a week for the first 4 weeks, while groups 4-6 received p-MCA at three different doses of 20, 40 and 80 mg/kg b.wt. p.o. everyday for 16 weeks. A significant increase in carcinogen-activating enzymes (cytochrome P450, cytochrome b5, cytochrome P4502E1, NADH-cytochrome-b5-reductase and NADPH-cytochrome-P450 reductase) with concomitant decrease in phaseII enzymes, DT-Diaphorase, glutathione S-transferase, UDP-glucuronyl-transferase and gamma glutamyltransferase were observed in group3 compared to control. DMH treatment significantly increased the activities of feacal and colonic bacterial enzymes (ß-glucosidase, ß-galactosidase, ß-glucuronidase, nitroreductase, sulphatase and mucinase). p-MCA supplementation (40 mg/kg b.wt) to carcinogen exposed rats inhibited these enzymes, which were near those of control rats. The formation of dysplastic aberrant crypt foci in the colon and the histopathological observations of the liver also supports our biochemical findings. p-MCA (40 mg/kg b.wt.) offers remarkable modulating efficacy of biotransforming bacterial and xenobiotic metabolizing enzymes in colon carcinogenesis.

The effect of rosmarinic acid on 1,2-dimethylhydrazine induced colon carcinogenesis.

This study was carried out to investigate the chemopreventive potential of rosmarinic acid (RA) against 1,2-dimethylhydrazine (DMH) induced rat colon carcinogenesis by evaluating the effect of RA on tumour formation, antioxidant enzymes, cytochrome P450 content, p-nitrophenol hydroxylase and GST activities. Rats were divided into six groups and fed modified pellet diet for the entire experimental period. Group 1 served as control, group 2 received RA (10 mg/kgb.w.). Groups 3-6 were induced colon cancer by injecting DMH (20 mg/kgb.w.) subcutaneously once a week for the first four weeks (groups 3-6). In addition, RA was administered at the doses of 2.5, 5 and 10 mg/kgb.w. to groups 4-6 respectively. DMH treated rats showed large number of colonic tumours; decreased lipid peroxidation; decreased antioxidant status; elevated CYP450 content and PNPH activities; and decreased GST activity in the liver and colon. Supplementation with RA (5 mgkg/b.w.) to DMH treated rats significantly decreased the number of polyps (50%); reversed the markers of oxidative stress (21.0%); antioxidant status (38.55%); CYP450 content (29.41%); and PNPH activities (21.9%). RA at the dose of 5 mg/kgb.w. showed a most pronounced effect and could be used as a possible chemopreventive agent against colon cancer.