Vitamin D: molecular mechanism of action.

Christakos, Sylvia,Dhawan, Puneet,Benn, Bryan,Porta, Angela,Hediger, Matthias,Oh, Goo T,Jeung, Eui-Bae,Zhong, Yan,Ajibade, Dare,Dhawan, Kopal,Joshi, Sneha New York Academy of Sciences 2007 Annals of the New York Academy of Sciences Vol.1116 No.1

<P>Vitamin D maintains calcium homeostasis and is required for bone development and maintenance. Recent evidence has indicated an interrelationship between vitamin D and health beyond bone, including effects on cell proliferation and on the immune system. New developments in our lab related to the function and regulation of target proteins have provided novel insights into the mechanisms of vitamin D action. Studies in our lab have shown that the calcium-binding protein, calbindin, which has been reported to be a facilitator of calcium diffusion, also has an important role in protecting against apoptotic cell death in different tissues including protection against cytokine destruction of osteoblastic and pancreatic beta cells. These findings have important implications for the therapeutic intervention of many disorders including diabetes and osteoporosis. Recent studies in our laboratory of intestinal calcium absorption using calbindin-D(9k) null mutant mice as well as mice lacking the 1,25-dihydroxyvitamin D(3) (1,25(OH)(2)D(3)) inducible epithelial calcium channel, TRPV6, provide evidence for the first time of calbindin-D(9k) and TRPV6 independent regulation of active calcium absorption. Besides calbindin, the other major target of 1,25(OH)(2)D(3) in intestine and kidney is 25(OH)D(3) 24 hydroxylase (24(OH)ase), which is involved in the catabolism of 1,25(OH)(2)D(3). In our laboratory we have identified various factors that cooperate with the vitamin D receptor in regulating 24(OH)ase expression including C/EBP beta, SWI/SNF (complexes that remodel chromatin using the energy of ATP hydrolysis) and the methyltransferases, CARM1 and G9a. Evidence is also presented for C/EBP beta as a nuclear coupling factor that coordinates regulation of osteopontin by 1,25(OH)(2)D(3) and PTH. Our findings define novel mechanisms that may be of fundamental importance in understanding how 1,25(OH)(2)D(3) mediates its multiple biological effects.</P>

Inhibitory mechanism of lycopene on cytokine expression in experimental pancreatitis.

New York Academy of Sciences 2011 Annals of the New York Academy of Sciences Vol.1229 No.1

<P>Reactive oxygen species (ROS) are important mediators to induce pancreatitis. Serum levels of antioxidant enzymes and carotenoids including lycopene are lower in patients with pancreatitis than those of healthy subjects. The cholecystokinin (CCK) analog cerulein induces similar pathologic events as shown in human pancreatitis. Recent studies show that high doses of cerulein activate NF-κB and induce the expression of inflammatory cytokines, in pancreatic acinar cells, which is mediated by the activation of NADPH oxidase. Lycopene functions as a very potent antioxidant to suppress the induction of inflammatory cytokines, in pancreatic acinar cells stimulated with cerulein. In this review, the possible beneficial effect of lycopene on experimental pancreatitis shall be discussed based on its antioxidant activity.</P>

Myricetin is a potent chemopreventive phytochemical in skin carcinogenesis.

Kang, Nam Joo,Jung, Sung Keun,Lee, Ki Won,Lee, Hyong Joo New York Academy of Sciences 2011 Annals of the New York Academy of Sciences Vol.1229 No.1

<P>Myricetin is a widely distributed flavonol that is found in many plants, including tea, berries, fruits, vegetables, and medicinal herbs. Abundant sources provide interesting insights into the multiple mechanisms by which myricetin mediates chemopreventive effects on skin cancer. Myricetin strongly inhibited tumor promoter-induced neoplastic cell transformation by inhibiting MEK, JAK1, Akt, and MKK4 kinase activity directly. In a mouse skin model, myricetin attenuated the ultraviolet B (UVB)-induced COX-2 expression and skin tumor formation by regulating Fyn. Myricetin-mediated inactivation of Akt in the UVB response plays a role in regulating UVB-induced carcinogenesis. Recently, myricetin was found to inhibit UVB-induced angiogenesis by targeting PI3-K in an SKH-1 hairless mouse skin tumorigenesis model. Raf Icinase is a critical target for myricetin in inhibiting the UVB-induced formation of wrinkles and suppression of type I procollagen and collagen levels in mouse skin. Accumulated data suggest that myricetin acts as a promising agent for the chemoprevention of skin cancer.</P>

Celecoxib potentiates the anticancer effect of cisplatin on vulvar cancer cells independently of cyclooxygenase.

Kim, Su-Hyeon,Kim, Su-Hyeong,Song, Yoo-Choel,Song, Yong-Sang New York Academy of Sciences 2009 Annals of the New York Academy of Sciences Vol.1171 No.1

<P>Cyclooxygenase-2 (COX-2) has been found to be associated with the development and progression of various cancers. Our previous study showed a high expression rate of COX-2 in paraffin-embedded tissue specimens from patients with vulvar cancer. In this study, we evaluated the efficacy of celecoxib, a selective COX-2 inhibitor, as a chemosensitizing agent with cisplatin in vulvar cancer cells A431 and SW962. COX-2 was expressed in both A431 and SW962 vulvar cancer cell lines. COX-1 was expressed in A431 but not in SW962. MTT [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazoliumbromide] assay showed that treatment with 30 micromol/L celecoxib had no effect on cell growth in A431 cells for 72 h. However, combined treatment with celecoxib and cisplatin induced a significant reduction in cell growth compared to single treatment with cisplatin. Interestingly, single treatment with celecoxib or cisplatin and combined treatment of 10 micromol/L celecoxib with 10 micromol/L cisplatin increased COX-2 expression. However, the combination of 30 micromol/L celecoxib and 30 micromol/L cisplatin reduced COX-2 expression to the control state. Inhibition of cell growth by celecoxib alone and in combination with cisplatin was independent of the expression level of COX-2 induced by these agents. While treatment with 10 micromol/L celecoxib or 10 micromol/L piroxicam significantly suppressed the activity of COX enzymes, neither agent affected the growth of A431 and SW962 cells at this concentration. Taken together, celecoxib could be used as a chemosensitizing agent in vulva cancer cells; the anticancer activity of celecoxib seemed to be independent of COX.</P>

Growth hormone-STAT5 regulation of growth, hepatocellular carcinoma, and liver metabolism.

Baik, Myunggi,Yu, Ji Hoon,Hennighausen, Lothar New York Academy of Sciences 2011 Annals of the New York Academy of Sciences Vol.1229 No.1

<P>The liver is a primary target of growth hormone (GH). GH signals are mediated by the transcription factor signal transducer and activator of transcription 5 (STAT5). Here, we focus on recent discoveries about the role of GH-STAT5 signaling in hepatic physiology and pathophysiology. We discuss roles of the GH-STAT5 axis in body growth, lipid metabolism, and the cell cycle pertaining to hepatosteatosis, fibrosis, and hepatocellular carcinoma. Finally, we discuss recent discoveries about the role of GH-STAT5 in sex-specific gene expression and bile acid, steroid, and drug metabolism.</P>

Assessing estrogen signaling aberrations in breast cancer risk using genetically engineered mouse models.

Furth, Priscilla A,Cabrera, M Carla,Dí,az-Cruz, Edgar S,Millman, Sarah,Nakles, Rebecca E New York Academy of Sciences 2011 Annals of the New York Academy of Sciences Vol.1229 No.1

<P>Aberrations in estrogen signaling increase breast cancer risk. Molecular mechanisms that impact breast cancer initiation, promotion, and progression can be investigated using genetically engineered mouse models. Increasing estrogen receptor alpha (ER관) expression levels twofold is sufficient to initiate and promote breast cancer progression. Initiation and promotion can be increased by p53 haploinsufficiency and by coexpressing the nuclear coactivators amplified in breast cancer 1 (AIB1) or the splice variant AIB1??3. Progression to invasive cancer is found with coexpression of these nuclear coactivators as well as following a single dose of 7,12-dimethylbenz(a)anthracene. Loss of signal transducer and activator of transcription 5a reduces the prevalence of initiation and promotion but does not protect from invasive cancer development. Cyclin D1 loss completely interrupts mammary epithelial proliferation and survival when ER관 is overexpressed. Loss of breast cancer gene 1 increases estrogen signaling and cooperates with ER관 overexpression in initiation, promotion, and progression of mammary cancer.</P>

Tetramethoxy hydroxyflavone p7F downregulates inflammatory mediators via the inhibition of nuclear factor kappaB.

Lee, Hee-Gu,Kim, Hyoson,Oh, Won-Keun,Yu, Kyung-Ae,Choe, Yong-Kyung,Ahn, Jong-Seog,Kim, Dong-Soo,Kim, Soo-Hyun,Dinarello, Charles A,Kim, Kilhyoun,Yoon, Do-Young New York Academy of Sciences 2004 Annals of the New York Academy of Sciences Vol.1030 No.1

<P>Artemisia has been traditionally used in Korean herbal medicine to clear damp heat and to treat uteritis and jaundice. Flavonoids isolated from Artemisia are also known to possess anti-inflammatory activities. In this study, 5,6,3',5'-tetramethoxy 7,4'-hydroxyflavone (p7F) was isolated from Artemisia absinthium. We examined in vitro and in vivo regulatory functions of p7F on the production of nitric oxide (NO), prostaglandin E(2) (PGE(2)), and tumor necrosis factor-alpha (TNF-alpha) as well as the expression of inducible NO synthase (iNOS), cyclooxygenase-2 (COX-2), and collagen-induced arthritis. p7F inhibited the expression or production of proinflammatory mediators such as COX-2/PGE(2) and iNOS/NO in lipopolysaccharide (LPS)-stimulated RAW 264.7 cells. p7F also suppressed the serum level of TNF-alpha in mice treated with collagen and inhibited nuclear factor-kappaB (NF-kappaB) activation as well as NF-kappaB promoter activity in RAW 264.7 cells stimulated with LPS. This compound directly inhibited the intracellular accumulation of reactive oxygen species in hydrogen peroxide-stimulated RAW 264.7 cells. p7F has antioxidant activity and inhibits NF-kappaB activation. Taken together, these results suggest that p7F can be clinically applied to the treatment of inflammatory diseases.</P>

Independent Association of Tumor Necrosis Factor Polymorphism with Type 1 Diabetes Susceptibility

Shin, Hyoung Doo,Yang, Sei Won,Kim, Duk Hee,Park, Yongsoo Wiley (New York Academy of Sciences) 2008 Annals of the New York Academy of Sciences Vol.1150 No.1

<P>The contribution of SNPs in TNF genes to type 1 diabetes (T1D) is not well established and may be confounded by the linkage disequilibrium within the HLA genes. Seven SNPs in the TNF genes (TNFA and TNFB) were genotyped in a Korean cohort (398 T1D patients and 1422 nondiabetic controls), along with HLA DRB1, DQB1, and MICA (MHC class I chain-related genes). Among them, three SNPs (TNFB+318, TNFA-857, and TNFA-308) and two common TNF haplotypes showed significant association with the risk of T1D (P= 5 x 10(-3)-10(-5)). T1D patients were more often heterozygous for the alleles at the TNFB+318 (OR = 1.7, P= 10(-3)) and TNFA-308 (OR = 1.7, P < 10(-5)) than were the controls. Genetic association analyses of the DRB1, DQB1, and MICA alleles with the risk of T1D revealed dramatic associations in several alleles as expected. Independent analyses to discern the genetic effects of TNF polymorphisms on the risk of T1D suggested that these genetic influences might be not totally dependent on the nearby HLA genes. Our results support the hypothesis that two susceptibility loci in the MHC (one in the HLA class II and another in the central MHC region) act epistatically to increase susceptibility to T1D.</P>

Induction of Apoptosis of β Cells of the Pancreas by Advanced Glycation End-Products, Important Mediators of Chronic Complications of Diabetes Mellitus

Lim, Minsu,Park, Leejin,Shin, Geewook,Hong, Hekyung,Kang, Incheol,Park, Yongsoo Wiley (New York Academy of Sciences) 2008 Annals of the New York Academy of Sciences Vol.1150 No.1

<P>We herein report cytotoxicity of advanced glycation end-products (AGEs) on pancreatic beta cells. AGEs stimulated reactive oxygen species (ROS) generation but did not arrest proliferation of the INS-1 cell line. Pancreatic beta cell lines or primary cultured islets possess a receptor for AGE (RAGE), and its expression increased after AGE treatment. TUNEL staining and FACS analysis using annexin V/PI antibodies showed that apoptosis increased in INS-1 cells or primary cultured islets when incubated with BSA conjugated with glyceraldehyde (AGE2) or glucoaldehyde (AGE3), compared with those conjugated with glucose (AGE1). Reaction of INS-1 cells to Ki67, which is a cellular marker for proliferation, was also increased after AGE treatment. The ability of primary cultured islets to secrete insulin was retained even after AGE treatment under either low or high glucose conditions. The antiserum against RAGE partially prevented AGE-induced cellular events. Treatment of beta cells with the antioxidant metallothionein results in a significant reduction in pathologic changes. AGEs might be able to induce apoptosis as well as proliferation of pancreatic beta cell lines or primary cultured islets. Moreover, antibody array showed that RAD51 and RAD52 were significantly decreased in AGE2-treated INS-1 cells. AGEs might inhibit homologous DNA recombination for repairing DNA of INS-1 cells damaged by ROS generation. It might be suggested that treatment of AGEs resulted in ROS production and apoptosis through their receptor on pancreatic beta cells. AGEs might deteriorate function of pancreatic beta cells in patients with long-term hyperglycemia.</P>

TGFβ Plasmid Construction and Delivery for the Prevention of Type 1 Diabetes

Park, Leejin,Lee, Eunjig,Lee, Sangkyung,Lim, Minsu,Hong, Hekyung,Shin, Geewook,Park, Yongsoo Wiley (New York Academy of Sciences) 2008 Annals of the New York Academy of Sciences Vol.1150 No.1

<P>Studies of animals with spontaneous autoimmune diabetes have revealed that autoreactive T cells that mediate islet beta cell destruction can be manipulated by the administration of Th(2) cytokines. Using gene delivery to express the targeted protein, we can overcome the need for frequent administration of cytokines on account of their short half-lives. In this study, the effect of hTGFbeta gene delivery was evaluated both in vitro and in vivo using an adenovirus vector (Ad) constructed with an hTGFbeta cDNA. In vitro transfection assays of the construct in HepG2, beta cell lines, and islets showed good expression levels of hTGFbeta and activation of smad3. Ad-hTGFbeta enhanced differentiation and proliferation in the beta cell line or islets without causing apoptosis. Of interest, Ad-hTGFbeta transduction in CD4(+)CD25(-) T cells resulted in a significant enhanced expression of CD25 and a regulatory T cell-specific transcription factor, Foxp3. To evaluate in vivo efficacy, Ad-hTGFbeta was intravenously injected into 7-week-old NOD mice and compared to the transduction using the vector only. The Ad-hTGFbeta group had persistent gene expression for longer than 5 weeks, and high TGFbeta serum level was secreted. There was no difference in the degree of insulitis between the Ad-hTGFbeta group and controls. Although we found favorable in vitro results, such as decrease in islet apoptosis, enhanced proliferation and differentiation, and increase in the level of CD4(+)CD25(+) regulatory T cells, there was no difference in reduction of the development of T1D between controls and Ad-hTGFbeta-injected mice. Nevertheless, if we find the appropriate mode and timing of TGFbeta gene transduction, Ad-hTGFbeta gene therapy might be useful in therapeutic cytokine delivery for the treatment of T1D.</P>