Identification and potential use of a soluble tumor antigen for the detection of liver‐fluke‐associated cholangiocarcinoma induced in a hamster model

Abstract

A liver-fluke-associated cholangiocarcinoma (CCA), comparable to that occurring in humans, was induced by exposing Opisthorchis viverrini-infected hamsters to dimethylnitrosamine (DMN). Tumor masses were removed and histopathologically identified, then one portion was extracted for antigens used in the production of monoclonal antibodies (MAbs). The remaining portions were used to establish CCA cell lines. The antigens produced and secreted by these cell lines, as well as those originally present in the tissue extracts, possessed a 200-kDa glycoprotein that appeared to be immunologically distinct from other tumor markers. A specific MAb called 6E5 was used to set up a sandwich ELISA for the quantification of this antigen in the serum and bile of tumor-bearing animals. The assay system was sensitive enough to detect the antigen at concentrations below 10 ng/ml. The serum and biliary levels of this antigen were markedly elevated in animals with progressive tumors when compared with untreated controls. The serum taken serially from each animal that subsequently developed CCA showed a gradual but significant elevation of the antigen as carcinogenesis progressed. A few isolated animals exhibited a slight elevation of the antigen at a time as early as the end of DMN treatment, when the CCA should not yet have developed, judging from microscopic examination. The data from this animal model suggested that the CCA-associated soluble antigen defined by MAb 6E5 was a useful marker for the detection of tumors at an early stage of development.

Effects of Excretory/Secretory Products from Clonorchis sinensis and the Carcinogen Dimethylnitrosamine on the Proliferation and Cell Cycle Modulation of Human Epithelial HEK293T Cells

“…Over time, infection with C. sinensis can lead to cholangiocarcinoma; therefore, C. sinensis is classified as a carcinogen [3]. Hamsters that are infected with liver flukes such as C. sinensis or Opisthorchis viverrini are at the greater risk of developing cholangiocarcinoma through dimethylnitrosamine (DMN)-induced or inflammation-mediated carcinogenesis [5,6]. When the bile duct epithelial cells of an infected animal are exposed to high concentrations of N-nitroso compounds, neoplastic transformation may result [5][6][7].…”

“…Hamsters that are infected with liver flukes such as C. sinensis or Opisthorchis viverrini are at the greater risk of developing cholangiocarcinoma through dimethylnitrosamine (DMN)-induced or inflammation-mediated carcinogenesis [5,6]. When the bile duct epithelial cells of an infected animal are exposed to high concentrations of N-nitroso compounds, neoplastic transformation may result [5][6][7]. The N-nitroso compounds cause nitrosative and oxidative damage to nucleic acids, which may participate in the initiation and/or promotion of cholangiocarcinogenesis [8].…”

.ALPHA.-Naphthylisothiocyanate Induces Intrahepatic Bile Duct with Greater Proliferation in Female Rats than in Males

“…Furthermore, neither BOP (in females and males) nor DMN (in males) caused any neoplastic (or even non-neoplastic) liver cholangiocellular lesions with or without the subsequent ANIT administration. This may be due to the lack of initiating activity of BOP or DMN in rats, in contrast to hamsters [3][4][5][6][7][8] , and/or the lack of promoting activity of ANIT. At the dose employed here, 200 ppm, PCNA-positive bile duct epithelial cells did not increase in spite of bile duct proliferation.…”

“…It is therefore necessary to assess detailed mechanisms in appropriate animal models to establish mechanism-based strategies to control human ICC. A number of animal models of ICC have been developed in hamsters using combinations of chemical carcinogens, Opisthorchis infection and bile duct ligation [3][4][5][6][7][8] . However, only limited information is available about the genetic background of hamsters.…”

“…In this context, the present study was performed to investigate the effects of ANIT on the liver with or without initiating treatment with N-nitrosobis(2-oxopropyl)amine (BOP) or Nnitrosodimethylamine (DMN). BOP and DMN were selected, because both of them have been used in hamster ICC models [3][4][5][6][7][8] . Male hamsters have been used in previous experiments to produce ICC 4,7 , so we used only male animals in investigations using DMN.…”