Anti-angiogenic effects of the blue-green alga Arthrospira platensis on pancreatic cancer.

Arthrospira platensis, a blue-green alga, is a popular nutraceutical substance having potent antioxidant properties with potential anti-carcinogenic activities. The aim of our study was to assess the possible anti-angiogenic effects of A platensis in an experimental model of pancreatic cancer. The effects of an A platensis extract were investigated on human pancreatic cancer cells (PA-TU-8902) and immortalized endothelial-like cells (Ea.hy926). PA-TU-8902 pancreatic tumours xenografted to athymic mice were also examined. In vitro migration and invasiveness assays were performed on the tested cells. Multiple angiogenic factors and signalling pathways were analysed in the epithelial, endothelial and cancer cells, and tumour tissue. The A platensis extract exerted inhibitory effects on both migration and invasion of pancreatic cancer as well as endothelial-like cells. Tumours of mice treated with A platensis exhibited much lesser degrees of vascularization as measured by CD31 immunostaining (P = .004). Surprisingly, the VEGF-A mRNA and protein expressions were up-regulated in pancreatic cancer cells. A platensis inhibited ERK activation upstream of Raf and suppressed the expression of ERK-regulated proteins. Treatment of pancreatic cancer with A platensis was associated with suppressive effects on migration and invasiveness with various anti-angiogenic features, which might account for the anticancer effects of this blue-green alga.

Predictive role BLVRA mRNA expression in hepatocellular cancer.

 Introduction and aim. Hepatocellular carcinoma (HCC) is the most common primary malignant liver tumor. It is primarily caused by hepatic cirrhosis or chronic viral hepatitis. Hepatic carcinogenesis is associated with increased oxidative stress. Thus, the aim of our study was to assess expression of the genes involved in the homeostasis of oxidative stress in patients with HCC. MATERIAL AND METHODS: The study was performed on 32 patients with primary HCC (verified by liver histology in 29 patients) and 27 control subjects (in 11 subjects, liver histology was available either with no or minimal changes in the liver tissue). Gene expressions of heme oxygenase 1 (HMOX1), biliverdin reductase A/B (BLVRA/B), NADPH oxidase 2 (NOX2) and p22phox were analyzed in the liver and peripheral blood leukocytes (PBL) in the subjects. RESULTS: Compared to controls, almost a 3 times higher mRNA level of BLVRA was detected in livers of HCC patients (p = 0.002); while those of BLVRB as well as HMOX1 were unchanged (p > 0.05). In accord with these results in the liver tissue, BLVRA mRNA levels in PBL were also significantly increased in HCC patients (p = 0.012). mRNA levels of NOX2 and p22phox in the liver tissue, although higher in HCC patients, did not differ significantly compared to control subjects (p > 0.05). Nevertheless, NOX2 mRNA level in PBL was significantly higher in HCC patients (p = 0.003). CONCLUSIONS: BLVRA mRNA levels in the liver as well as in PBL are significantly higher in HCC patients most likely as a feedback mechanism to control increased oxidative stress associated with HCC progression.

Anti-cancer effects of blue-green alga Spirulina platensis, a natural source of bilirubin-like tetrapyrrolic compounds.

Spirulina platensis is a blue-green alga used as a dietary supplement because of its hypocholesterolemic properties. Among other bioactive substances, it is also rich in tetrapyrrolic compounds closely related to bilirubin molecule, a potent antioxidant and anti-proliferative agent. The aim of our study was to evaluate possible anticancer effects of S. platensis and S. platensis-derived tetrapyrroles using an experimental model of pancreatic cancer. The anti-proliferative effects of S. platensis and its tetrapyrrolic components [phycocyanobilin (PCB) and chlorophyllin, a surrogate molecule for chlorophyll A] were tested on several human pancreatic cancer cell lines and xenotransplanted nude mice. The effects of experimental therapeutics on mitochondrial reactive oxygen species (ROS) production and glutathione redox status were also evaluated. Compared to untreated cells, experimental therapeutics significantly decreased proliferation of human pancreatic cancer cell lines in vitro in a dose-dependent manner (from 0.16 g•L-1 [S. platensis], 60 µM [PCB], and 125 µM [chlorophyllin], p<0.05). The anti-proliferative effects of S. platensis were also shown in vivo, where inhibition of pancreatic cancer growth was evidenced since the third day of treatment (p < 0.05). All tested compounds decreased generation of mitochondrial ROS and glutathione redox status (p = 0.0006; 0.016; and 0.006 for S. platensis, PCB, and chlorophyllin, respectively). In conclusion, S. platensis and its tetrapyrrolic components substantially decreased the proliferation of experimental pancreatic cancer. These data support a chemopreventive role of this edible alga. Furthermore, it seems that dietary supplementation with this alga might enhance systemic pool of tetrapyrroles, known to be higher in subjects with Gilbert syndrome.

Antiproliferative effects of carbon monoxide on pancreatic cancer.

BACKGROUND: Carbon monoxide, the gaseous product of heme oxygenase, is a signalling molecule with a broad spectrum of biological activities. The aim of this study was to investigate the effects of carbon monoxide on proliferation of human pancreatic cancer. METHODS: In vitro studies were performed on human pancreatic cancer cells (CAPAN-2, BxPc3, and PaTu-8902) treated with a carbon monoxide-releasing molecule or its inactive counterpart, or exposed to carbon monoxide gas (500 ppm/24h). For in vivo studies, pancreatic cancer cells (CAPAN-2/PaTu-8902) were xenotransplanted subcutaneously into athymic mice, subsequently treated with carbon monoxide-releasing molecule (35 mg/kg b.w. i.p./day), or exposed to safe doses of carbon monoxide (500 ppm 1h/day; n = 6 in each group). RESULTS: Both carbon monoxide-releasing molecule and carbon monoxide exposure significantly inhibited proliferation of human pancreatic cancer cells (p<0.05). A substantial decrease in Akt phosphorylation was observed in carbon monoxide-releasing molecule compared with inactive carbon monoxide-releasing molecule treated cancer cells (by 30-50%, p<0.05). Simultaneously, carbon monoxide-releasing molecule and carbon monoxide exposure inhibited tumour proliferation and microvascular density of xenotransplanted tumours (p<0.01), and doubled the survival rates (p<0.005). Exposure of mice to carbon monoxide led to an almost 3-fold increase in carbon monoxide content in tumour tissues (p=0.006). CONCLUSION: These data suggest a new biological function for carbon monoxide in carcinogenesis, and point to the potential chemotherapeutic/chemoadjuvant use of carbon monoxide in pancreatic cancer.

Beyond plasma bilirubin: the effects of phototherapy and albumin on brain bilirubin levels in Gunn rats.

BACKGROUND & AIMS: Severe unconjugated hyperbilirubinemia, as occurs in Crigler-Najjar disease and neonatal jaundice, carries the risk of neurotoxicity. This neurotoxicity is related to the increased passage of free bilirubin (UCB(free)), the fraction of bilirubin that is not bound to plasma proteins, into the brain. We hypothesized that albumin treatment would lower the UCB(free) fraction, and thus decrease bilirubin accumulation in the brain. METHODS: We treated chronic (e.g., as a model for Crigler-Najjar disease) and acute hemolytic (e.g., as a model for neonatal jaundice) moderate hyperbilirubinemic Gunn rats with phototherapy, human serum albumin (HSA) or phototherapy+HSA. RESULTS: In the chronic model, adjunct HSA increased the efficacy of phototherapy; it decreased plasma UCB(free) and brain bilirubin by 88% and 67%, respectively (p<0.001). In the acute model, adjunct HSA also increased the efficacy of phototherapy; it decreased plasma UCB(free) by 76% (p<0.001) and completely prevented the hemolysis-induced deposition of bilirubin in the brain. Phototherapy alone failed to prevent the deposition of bilirubin in the brain during acute hemolytic jaundice. CONCLUSIONS: We showed that adjunct HSA treatment decreases brain bilirubin levels in phototherapy-treated Gunn rats. We hypothesize that HSA decreases these levels by lowering UCB(free) in the plasma. Our results support the feasibility of adjunct albumin treatment in patients with Crigler-Najjar disease or neonatal jaundice.

Reduction of bilirubin ditaurate by the intestinal bacterium Clostridium perfringens.

Bilirubin is degraded in the human gut by microflora into urobilinoids. In our study we investigated whether the bilirubin-reducing strain of Clostridium perfringens can reduce bilirubin ditaurate (BDT), a bile pigment of some lower vertebrates, without hydrolysis of the taurine moiety. C. perfringes was incubated under anaerobic conditions with BDT; reduction products were quantified by spectrophotometry and separated by TLC. Based on Rf values of BDT reduction products and synthetic urobilinogen ditaurate, three novel taurine-conjugated urobilinoids were identified. It is likely that bilirubin-reducing enzyme(s) serve for the effective disposal of electrons produced by fermentolytic processes in these anaerobic bacteria.

Bilirubin accumulation and Cyp mRNA expression in selected brain regions of jaundiced Gunn rat pups.

INTRODUCTION: Few data exist on regional brain bilirubin content in the neonatal period when acute bilirubin-induced neurologic damage (BIND) may occur, and no information is available on regional brain expression of cytochrome P450 monooxygenases (Cyps) that oxidize bilirubin. METHODS: Bilirubin content was analyzed by high-performance liquid chromatography and Cyp1a1, 1a2, and 2a3 mRNA expression was analyzed by quantitative PCR (qPCR) in cortex (Cx), cerebellum (Cll), superior colliculi (SC), and inferior colliculi (IC) of 17-d-old hyperbilirubinemic (jj) Gunn rat pups before and after administration of sulphadimethoxine to acutely displace bilirubin from plasma albumin. RESULTS: There was no difference in bilirubin content among brain regions in untreated rats. After intraperitoneal sulphadimethoxine, bilirubin content peaked at fourfold in Cx and SC at 1 h; but at 11- to 13-fold in Cll and IC at 24 h; returning to control levels at 72 h. The Cyp mRNA peaked at 30-70 times control at 1 h in Cx and SC, but at 3-9 times control at 24 h in Cll and IC. DISCUSSION: The close relationship in distinct brain regions between the extent of bilirubin accumulation and induction of mRNA of Cyps suggests Cyps may have a role in protecting selected brain areas from bilirubin neurotoxicity.

Structural basis of UV DNA-damage recognition by the DDB1-DDB2 complex.

Ultraviolet (UV) light-induced pyrimidine photodimers are repaired by the nucleotide excision repair pathway. Photolesions have biophysical parameters closely resembling undamaged DNA, impeding discovery through damage surveillance proteins. The DDB1-DDB2 complex serves in the initial detection of UV lesions in vivo. Here we present the structures of the DDB1-DDB2 complex alone and bound to DNA containing either a 6-4 pyrimidine-pyrimidone photodimer (6-4PP) lesion or an abasic site. The structure shows that the lesion is held exclusively by the WD40 domain of DDB2. A DDB2 hairpin inserts into the minor groove, extrudes the photodimer into a binding pocket, and kinks the duplex by approximately 40 degrees. The tightly localized probing of the photolesions, combined with proofreading in the photodimer pocket, enables DDB2 to detect lesions refractory to detection by other damage surveillance proteins. The structure provides insights into damage recognition in chromatin and suggests a mechanism by which the DDB1-associated CUL4 ubiquitin ligase targets proteins surrounding the site of damage.