단기간 철 과다투여가 실험적으로 유발된 간세포 증식성 병변에 미치는 영향

Abstract

[한글]

간은 철 대사에 주요한 역할을 담당하는 장기로서 철이 과다하게 축적되면 촉매작용을 일으키는 철의 증가로 인한 자유기 형성과 지방의 과산화에 의한 세포손상이 초래되고 그 결과 간섬유화, 간경변증 및 간세포암종이 발생할 수 있다. Transferrin receptor(TR)는 철의 세포내 운반에 중요한 수용체이며 세포성장에도 중요한 역할을 하는 것으로 알려져 있다. 본 연구에서는 철이 실험적 간암발생 과정중에 나타나는 일련의 증식성 병변들에 미치는 영향을 알아 보기 위하여 저항성 간세포 모형(Solt-Farther방법)을 이용하여 화학발암제를 단독 또는 철과 병합투여하여 유발한 중식성 병변의 철분 함량, 조직학적 변화, TR의 표현 양상, 세포의 증식능 및 DNA 배수성을 비교 검색하였으며, 그 결과는 다음과 같다. 간 조직의 철 함량은 식이 철투여시 현격히 증가하였으며, 화학발암제 투여군에서

는 증식성 병변의 발생이 증가함에 따라 점차 감소하는 양상을 보였다. 화학발암제 투여군에서는 부분 간절제 후 시간이 경과함에 따라 난원형 세포의 증식, 그리고 호염기성 세포 중식병소-호산성 세포 중식병소-증식결절과 같은 일련의 증식성 병변이 발생하였다.

난원형 세포의 BrdU표지지수는 간세포 증식성 병변에 비해 높았으며, 두 병변 모두에서 부분 간절제 후 시간이 경과함에 따라 점차 감소하였고 철 병합투여에 따른 의미있는 차이는 업었다. 철을 투여한 대조군의 간세포내에서는 철 축적이 관찰되었으며, 철과 발암제를 병합투여한 군에서 주위의 간세포에는 철 축적이 있었으나 증식성 병변을 구성하는 간세포에는 철 축적이 없었다. TR은 대조군에서는 간세포의 세포막과 세포질에서 모두 표현되며 철 축적이 증가함에 따라 그 표현이 감소되었으나, 화학 발암제 투여군에서는 철 병합투여에 관계없이 간세포 증식성 병변이 발생됨에 따라 병변을 구성하는 간세포의 세포막에서 강하게 표현되었다. DNA 배수성 유형은 모든 군에서 주로 二倍數性과 四倍數性의 세포군을 갖는 多倍數性의 양상을 보였으나 중식성 병변이 발생함에 따라 철 병합투여에 관계없이 二倍數性 세포군의 비율이 증가하는 경향이었다. 이상의 결과를 종합하면 흰쥐의 실험적인 간암유발 과정에서 단기간 철 과다투여는 증식성 병변의 발생을 억제 또는 촉진시키지 않으며, 철 병합투여에 관계없이 증식성 병변에서는 철 함량이 감소하고 TR의 세포막 표현이 증가하는 것으로 보아 TR의 세포질내 이동에 장애가 초래되는 것으로 생각된다.

The short-term effect of iron on the hyperplastic lesion in the chemically induced

hepatic carcinogenesis

Young Nyun Park

Department of Medical Science The Graduate School, Yonsei University

(Directed by Assistant Professor Woo Hee Jung)

Liver is a major site of iron metabolism and storage. The major pathological

effects of chronic hepatic iron load are fibrosis, cirrhosis and hepato cellular

carcinoma and the toxicity of iron is most likely related to enhancement of

oxidative stress and free radical reactions stimulated by iron. Transferrin

recptor(TR) performs the maior function of binding and internalization its specific

iron-loaded ligand, transferrin, and its expression is closely linked to the

proliferaiton status of the cell.

This study was undertaken to elucidate the short-term effect of iron on the

hyperplastic lesion in chemically induced hepatic carcinogenesis. The resistent

hepatocyte model(Solt-Farber method)was chosen for a rat model of carcinogenesis

and Sprague-Dawley rat were divided into the fort-lowing groups: normal control,

iron-rich diet with or without hydroxyquinoline control, carcinogen administered,

carcingen plus iron-rich diet with or without hydroxyquinoline. Hepatic iron

con-tent, microscopic chanties of liver, expression of transferrin recenter(TR),

cell kinetics of hyperplastic lesions and DNA ploidy were studied. In the

carcinogen administered group oval cell proliferation and hyperplastic lesion of

hepatocyte(basophilic foci-eosinophilc foci-hyperplastic nodule) were developed

regardless of administration of iron. BrdU labelling indices of oval cell was

higher than those of hepatocytes in hyperplastic lesion and iron administration did

not alter the proliferative activity of hyperplastic lesion. The hepatic iron

content of the carcinogen administered group tended to decrease as the hyperplastic

lesion developed, which contrasted with markedly increased iron content in the

control group fed with iron rich diet. The normal hepatocytes skewed stainable iron

in rats fed with iron rich diet. However, the hepatocytes of hyperplastic lesion

failed to show iron accumulation and the hepatocytes of hyperplastic leasion

revealed strong membranous expression of TR in contrast to the membranous and

cytoplasmic expression of TR in hepatocyte of the control group. DNA ploidy of

hepatocytes were polyploidy, Predominantly composed of tetraploidy and diploidy in

the control group and in the carcinogen adminstered group the population of

diploidy was increased in relation to the degree of proliferation status. The DNA

ploidy of hepatocyte appeared to be altered from polyploidy to diploidydiploidy

divisional growth regardless of iron administration.

In conclusion, these findings indicate that short-term administration of iron

does not enhance or repress the development of hyperplastic lesion in chemically

induced hepatic carcinogenesis and hepatic iron content is decreased in

hyperplastic lesions regardless of combined administration of iron in conjunction

with increased membaranous expression of TR, which may reflect disturbance of

intracytoplasmic transport of TR.

[영문]

Liver is a major site of iron metabolism and storage. The major pathological effects of chronic hepatic iron load are fibrosis, cirrhosis and hepato cellular carcinoma and the toxicity of iron is most likely related to enhancement of oxidative stress and free radical reactions stimulated by iron. Transferrin recptor(TR) performs the maior function of binding and internalization its specific iron-loaded ligand, transferrin, and its expression is closely linked to the proliferaiton status of the cell.

This study was undertaken to elucidate the short-term effect of iron on the hyperplastic lesion in chemically induced hepatic carcinogenesis. The resistent hepatocyte model(Solt-Farber method)was chosen for a rat model of carcinogenesis and Sprague-Dawley rat were divided into the fort-lowing groups: normal control, iron-rich diet with or without hydroxyquinoline control, carcinogen administered, carcingen plus iron-rich diet with or without hydroxyquinoline. Hepatic iron con-tent, microscopic chanties of liver, expression of transferrin recenter(TR),

cell kinetics of hyperplastic lesions and DNA ploidy were studied. In the carcinogen administered group oval cell proliferation and hyperplastic lesion of hepatocyte(basophilic foci-eosinophilc foci-hyperplastic nodule) were developed

regardless of administration of iron. BrdU labelling indices of oval cell was higher than those of hepatocytes in hyperplastic lesion and iron administration did not alter the proliferative activity of hyperplastic lesion. The hepatic iron content of the carcinogen administered group tended to decrease as the hyperplastic lesion developed, which contrasted with markedly increased iron content in the control group fed with iron rich diet. The normal hepatocytes skewed stainable iron in rats fed with iron rich diet. However, the hepatocytes of hyperplastic lesion failed to show iron accumulation and the hepatocytes of hyperplastic leasion revealed strong membranous expression of TR in contrast to the membranous and cytoplasmic expression of TR in hepatocyte of the control group. DNA ploidy of hepatocytes were polyploidy, Predominantly composed of tetraploidy and diploidy in

the control group and in the carcinogen adminstered group the population of diploidy was increased in relation to the degree of proliferation status. The DNA ploidy of hepatocyte appeared to be altered from polyploidy to diploidydiploidy divisional growth regardless of iron administration.

In conclusion, these findings indicate that short-term administration of iron does not enhance or repress the development of hyperplastic lesion in chemically induced hepatic carcinogenesis and hepatic iron content is decreased in

hyperplastic lesions regardless of combined administration of iron in conjunction with increased membaranous expression of TR, which may reflect disturbance of intracytoplasmic transport of TR.