Inhibition of TNFα-interacting protein α (Tipα)-associated gastric carcinogenesis by BTG2(/TIS21) via downregulating cytoplasmic nucleolin expression

To understand the regulation of Helicobacter pylori (H. pylori)-associated gastric carcinogenesis, we examined the effect of B-cell translocation gene 2 (BTG2) expression on the biological activity of Tipα, an oncoprotein secreted from H. pylori. BTG2, the human ortholog of mouse TIS21 (BTG2(/TIS21)), has been reported to be a primary response gene that is transiently expressed in response to various stimulations. Here, we report that BTG2 is constitutively expressed in the mucous epithelium and parietal cells of the gastric gland in the stomach. Expression was increased in the mucous epithelium following H. pylori infection in contrast to its loss in human gastric adenocarcinoma. Indeed, adenoviral transduction of BTG2(/TIS21) significantly inhibited Tipα activity in MKN-1 and MGT-40, human and mouse gastric cancer cells, respectively, thereby downregulating tumor necrosis factor-α (TNFα) expression and Erk1/2 phosphorylation by reducing expression of nucleolin, a Tipα receptor. Chromatin immunoprecipitation proved that BTG2(/TIS21) inhibited Sp1 expression and its binding to the promoter of the nucleolin gene. In addition, BTG2(/TIS21) expression significantly reduced membrane-localized nucleolin expression in cancer cells, and the loss of BTG2(/TIS21) expression induced cytoplasmic nucleolin availability in gastric cancer tissues, as evidenced by immunoblotting and immunohistochemistry. Higher expression of BTG2 and lower expression of nucleolin were accompanied with better overall survival of poorly differentiated gastric cancer patients. This is the first report showing that BTG2(/TIS21) inhibits nucleolin expression via Sp1 binding, which might be associated with the inhibition of H. pylori-induced carcinogenesis. We suggest that BTG2(/TIS21) is a potential inhibitor of nucleolin in the cytoplasm, leading to inhibition of carcinogenesis after H. pylori infection.

Protein Methylation and Interaction with the Antiproliferative Gene, BTG2(/TIS21/Pc3)

The last one and half a decade witnessed an outstanding re-emergence of attention and remarkable progress in the field of protein methylation. In the present article, we describe the early discoveries in research and review the role protein methylation played in the biological function of the antiproliferative gene, BTG2(/TIS21/PC3).

Establishing MD-PhD Programs in the Graduate School of Medicine in Korea

An MD-PhD is a physician-scientist with dual degrees integrating both medical and postgraduate training. In the 21st century, MD-PhDs will represent the main power and leadership of biomedical research and biotechnology, which can lead to national wealth in the very near future. Their education is supported primarily by the special grant from MSTP (medical scientist training program) owned by NIH-NIGMS (NIH-National Institute of General Medical Sciences) and partly by a non-MSTP grant prepared by each school. Since 2004, AAMC (Association of American Medical Colleges) approved MD-PhD section in the GREAT Group (Group on Graduate Research, Education, and Training) to promote the development, growth, and nurturing of physician-scientist training programs by representing the interest of MD-PhD programs. For successful launching of the combined MD-PhD program in the graduate schools of medicine in Korea, the following issues must be resolved as soon as possible: full scholarship support during the 7-year program, exemption from mandatory military service following graduation, official approval of PhD degree in the professional medical school, and introduction of the MD-PhD combined degree program to laypersons. Therefore, I strongly urge Korean government to take time and determine the budget for nurturing MD-PhD students to develop as biomedical leaders to bring national prosperity as well as world-class scientists in the 21st century.

Ito Cell Activity and Hepatocyte Proliferation Activity According to Collagen Content in Liver Cirrhosis / 대한간학회지

BACKGROUND/AIMS: Liver cirrhosis is an end-stage liver disease. Ito cell is known to have central role in fibrogenes is of liver cirrhosis. But collagen content and Ito cell activity in liver cirr hosis have received little attention. So Ito cell activity and hepatocyte proliferation activity according to collagen content was investigated. WAF-1 and c- met were studied to evaluate the effect of cell cycle. METHODS: We analyzed 56 cases of liver cirrhosis ( viral:41, biliary:11, alcoholic:2, Wilson' s disease:2). Collagen content was measured by spectrophot ometry. Ito cell activity and prolifer ation index was measured by-SMA and Ki- 67 immunohistochemistry. RESULTS: In viral cirrhosis, high collagen group showed increased Ito cell activity compared to low collagen group. There was no difference in hepatocyte prolifer ation activity bet ween high and low collagen group in viral cirrhosis. In biliary cirrhos is, high collagen group showed increased Ito cell activity in septal zones compared to low collagen group. WAF- 1and c- met were negative in most of cases. CONCLUSION: Collagen content of liver cirrhosis is closely related to increment of activated Ito cells . Ito cell activity was prominent in septal zones than in parenchymal areas of viral cirrhosis and that was only significant in septal zones of biliary cirrhosis. There is no correlation bet ween collagen content and hepatocyte proliferation activity.

The Relevance of Degree of Liver Fibrosis, Ito cell, and PKC Activity in Hepatic Fibrogenesis / 대한간학회지

BACKGROUND/AIMS: Hepatic fibrosis in rat induced by thioacet amide shares similar morphological and biochemical characteristics with human liver cirrhosis. Thioacetamide (T AA) initially induces accumulation of collagen in Disse space and eventually leads to macro- and micronodular cirrhos is. Ito cell was believed to play a main role in hepatic fibrosis. And it s activity was known to be regulated by the expression of various genes. But little has been discovered about the upstream signal trans duction pathway of these genes in hepatic fibrosis. The expression of genesrelated to Ito cell activity was regulated by many transcription factors , the activity of which was regulated by protein kinase C( PKC) is oforms. So it is s upposed that PKC could be as s ociated with fibrosis in liver. METHODS: We investigated the correlation of PKC is oforms and It ocell activity in the course of hepatic fibrosis using TAA induced rat liver cirrhosis model. We used six week- old male rats , and administered 0.03% TAA in drinking water. The animals were sacrificed at 9, 20, and 30 weeks after TAA administration. The degree of hepatic fibrosis was evaluated by measuring the total amount of collagen.-SMA immunohist ochemical st aining of liver tissue was done to determine the Ito cell activity. The expression pattern of PKC isoforms was investigated by West ern blotting. RESULTS: In TAA- treated group, collagen cont ent and Ito cell activity did not increase until 30 weeks and 20 weeks of treatment , respectively, while in control group collagen cont ent and Ito cell activity were not detected. Collagen content showed linear correlation with Ito cell activity. This implied that the proliferation of activated Ito cells was prior to the increase of collagen content. In view of expression pattern of PKC is oforms, PKC alpha showed no difference in TAA- treated group and control group. In TAA-treated group, PKCbeta1 exhibited increased level of expression in both particulate and cytosolic forms at 9 weeks, while PKCdelta and PKC epsilon showed striking shift to particulated form. After 20 weeks, all of the PKC beta1, delta, and epsilon degenerated and showed remarkably decreased level of expression. This suggested PKC alpha had no relation to hepatic fibrosis,while PKC beta1, delta, and epsilon, showing activity at 9 weeks, were related to fibrosis og liver. In response to fibrogenic factors, molecules engaged in intracellular signal transduction pathway like PKC beta1, delta, and epsilon, began to change prior to the increase of Ito cell activity, morphologic changes and alterations of collagen content. CONCLUSION: Our results strongly suggest that the activity of PKC isoforms play an important role in early step of hepatic fibrosis, while accompanying Ito cell activity do in later step.

Uranyl Nitrate Induced Polyuric Acute Tubular Necrosis in Rats

We investigated the pathobiological course of uranyl nitrate (UN) induced polyuric acute tubular necrosis (ATN) in male Sprague Dawley rats. UN (5mg/kg 15mg/kg and 3Omg/kg) in 5% NaHCO3 induced weight loss, polydipsia, and polyuria 24 hrs after injection when compared to the controls which were treated with 5% NaHCO3 only. Twenty four hours following the injection of UN, serum creatinine and blood urea nitrogen levels had increased. These changes continued for at least 72 hours, although the concentration of uranium had decreased. Light microscopic studies conducted 24 hours after injection, revealed partial degeneration and necrosis of the proximal tubules and many casts m the distal convoluted tubules. These changes progressed for 72 hours. Despite this tubular damage, the glomeruli were relatively intact. 5 days after injection, the epithelial cells lining the proximal tubules displayed regenerative activities; these findings were more prominent after 10 days. Through electron microscopic examination, we observed the destruction of mitochondria in the proximal tubular cells, a possible cause of polyuria. Ten days post injection regenerative activities in the proximal tubular cells showed that the maturation of intracellular organelles followed the proliferation of the premature cells.

High Activities of Protein Kinases C and M in Fresh Human Stomach and Breast Tumors

The activities of Ca+2-PL dependent protein Kinase (PKC) and independent protein kinase(RKM) were measured in human stomach and breast tumors and in the respective counterparts of normal tissue. Expression of c-fos and c-myc of the tissues were also measured. RNAs of c-fos and c-myc were unexpectedly high in the tissue from normal stomach and breast as well as in all cancer tissue. On the other hand, cytosolic and particulate PKC activities were higher in the tumors as compared to those of normal controls. Notably, some cases exhibited. altered activities of PKC i.e. increased RKM activities as high as RKC, which might be related to the autocrine control of growth in the tumor mass.