No abstract

Various natural carotenoids, besides beta-carotene, were proven to have anticarcinogenic activity, and some of them showed more potent activity than beta-carotene. Thus, these carotenoids (alpha-carotene, lutein, zeaxanthin, lycopene, beta-cryptoxanthin, fucoxanthin, astaxanthin, capsanthin, crocetin and phytoene), as well as beta-carotene, may be useful for cancer prevention. In the case of phytoene, the concept of 'bio-chemoprevention', which means biotechnology-assisted method for cancerchemoprevention, may be applicable. In fact, establishment of mammalian cells producing phytoene was succeeded by the introduction of crtB gene, which encodes phytoene synthase, and these cells were proven to acquire the resistance against carcinogenesis. Antioxidative phytoene-containing animal foods may be classified as a novel type of functional food, which has the preventive activity against carcinogenesis, as well as the ability to reduce the accumulation of oxidative damages, which are hazardous for human health.

We previously performed a global analysis of the gene expression of gastric cancer cell lines established from metastases to the peritoneal cavity with the cDNA microarray method, which made it possible to analyse the expression of approximately 21 168 genes for the identification of novel markers for the detection of micrometastases in the peritoneal cavity. One of the upregulated genes is dopa decarboxylase (DDC), which is responsible for the synthesis of the key neurotransmitters dopamine and serotonine. We have examined its potential as a novel marker for the detection of peritoneal micrometastases of gastric cancer. DDC mRNA in the peritoneal wash from 112 gastric cancer patients was quantified for comparison of carcinoembryonic antigen (CEA) mRNA by means of real-time reverse transcriptase -polymerase chain reaction (RT -PCR) with a fluorescently labelled probe to predict peritoneal recurrence. The quantity of DDC and CEA correlated with wall penetration. Real-time RT -PCR could quantitate 10 -10 6 DDC-expressing gastric cancer cells per 10 7 mesothelial cells. The cutoff value was set at the upper limit of the quantitative value for noncancer patients, and those above this cutoff value constituted the micrometastasis (MM þ ) group. Of 15 cases with peritoneal dissemination, 13 were MM þ DDC (87% sensitivity), and one of 48 t1 cases was MM þ (98% specificity). DDC levels in peritoneal washes from patients with synchronous peritoneal metastases were more than 50 times higher than in those from patients without metastasis (Po0.01). For 15 cases of peritoneal dissemination (seven cases were cytologically positive), DDC was positive in 13 cases (87% sensitivity), but CEA failed to detect micrometastases in four cases (73% sensitivity), indicating that DDC is in some cases superior to CEA for the detection of peritoneal micrometastases of gastric cancer in terms of sensitivity as well as specificity, especially for poorly differentiated adenocarcinomas. A combination of CEA and DDC improved the accuracy of diagnosis up to 94%. These results suggest that DDC is potentially a novel marker for peritoneal dissemination of gastric cancer and that quantitative RT -PCR of DDC is reliable and efficient for the selection of patients for adjuvant intraperitoneal chemotherapy to prevent peritoneal recurrence.

Age-related changes in the brain transfer of blood-borne horseradish peroxidase (HRP) were examined by light microscopy in senescence-accelerated prone mice (SAMP8) and senescence-accelerated resistant mice (SAMR1). The intracerebral HRP transferred from the blood stream was reacted with tetramethyl benzidine (TMB) and the area showing the presence of HRP-TMB reaction products was morphometrically evaluated. Areas containing HRP reaction products in the medial CA1 region and medial dentate gyrus of the hippocampus were observed in 3- and 13-month-old SAMP8 and SAMR1. The mean percentage of the positive area for the HRP to the area of interest was significantly higher in the rostral portion of the hippocampus in 13-month-old than in 3-month-old SAMP8. On the other hand, age-related changes in the area positive for HRP-TMB reaction products in the cortices and the caudal portion of the hippocampus in SAMP8 were not observed. In addition, positive staining reaction for HRP was also observed in the dorsal portion of the thalamus of 13-month-old SAMP8. There were no significant age-related changes in the area positive for HRP-TMB reaction products in rostral and caudal portions of the cortices and the hippocampus of SAMR1. These findings suggest that blood-borne macromolecules have access to the medial and rostral portion of the hippocampus, that this phenomenon becomes more pronounced during the process of senescence in the SAMP8 brain and, moreover, that intravascular macromolecules have access to the dorsal portion (periventricular area) of the thalamus of 13-month-old SAMP8.

Glial fibrillary acidic protein (GFAP), the principal intermediate filament (IF) protein of mature astrocytes in the CNS, plays specific roles in astrocyte functions. GFAP has multiple phosphorylation sites at its N-terminal head domain. To examine the role of phosphorylation at these sites, we generated a series of substitution mutant mice in which phosphorylation sites (Ser/Thr) were replaced by Ala, in different combinations. Gfap(hm3/hm3) mice carrying substitutions at all five phosphorylation sites showed extensive decrease in both filament formation and amounts of GFAP. Gfap(hm1/hm1) and Gfap(hm2/hm2) mice, which carry substitutions at three of five sites and in different combinations, showed differential phenotypes. Although Gfap(hm3/hm3) mice retained GFAP filaments in Bergmann glia in the cerebellum, the (Gfap(hm3/hm3):Vim(-/-)) mice lacked GFAP filaments. Pulse-chase experiments of cultured astrocytes indicated that the Hm3-GFAP encoded by Gfap(hm3) was unstable particularly in the absence of vimentin, another IF protein. These results revealed the role of phosphorylation in turnover of GFAP and a synergistic role of GFAP and vimentin in the dynamics of glial filaments. The data further suggest that each of the phosphorylated sites has a distinct impact on the dynamics of GFAP.