- PPARgamma Ligand-Induced Decrease of in vivo Tumor Growth Accompanied by Increased Cytolytic Activity of Splenocytes.
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Kyu Yun Jang, Ki Hoon Yu, Hak Yong Lee, Kyung Ryoul Kim, Ha Na Choi, Eun Jung Cha, Ho Sung Park, Woo Sung Moon, Myoung Jae Kang, Dong Geun Lee
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Korean J Pathol. 2007;41(1):7-14.
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 Abstract
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- BACKGROUND
Recent studies have proposed the use of peroxisome proliferator activated receptor-gamma (PPARgamma) ligands as new chemotherapeutic agents for human malignant tumors. However the in vivo mechanism of PPARgamma ligands on cellular toxicity is not clear. Therefore we examined the anti-tumor effects of the PPARgamma ligand, rosiglitazone (ROS), in animal models.
METHODS
To evaluate the effect of RSO on splenocytes, an in vitro and in vivo study was performed. Cytolytic activity was measured by use of a 51Cr release assay. The splenic natural killer (NK) cell population and effector-target conjugation were measured by flow cytometric analysis.
RESULTS
In 9L glioma bearing rats, 30 mg/kg/d of ROS treatment induced a significant decrease of subcutaneous tumor growth accompanied by an increased cytolytic activity of splenocytes and of the splenic NKR-P1bright/CD3- NK cell population. In normal rats, systemic administration of ROS also increased the cytolytic activity of splenocytes, the splenic NK cell population, and effector-target conjugation.
Moreover, we found that a concentration of 20micrometer ROS caused an increase in the cytolytic activity of splenocytes, and a concentration of 50micrometer ROS increased effector-target conjugation in vitro.
CONCLUSIONS
These results suggest that increased splenic cytolytic activity and NK cell population may contribute to the anti-tumor effects of PPARgamma ligands in vivo.
However, the roles of NK cells in the PPARgamma ligand-induced anti-tumor activity should be further investigated.
- Expression of Epidermal Growth Factor Receptor Related Protein in Gallbladder Cancer: An Association with p53 Mutation.
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Ho Sung Park, Kyu Yun Jang, Kyung Ryoul Kim, Hak Yong Lee, Andrzej S Tarnawski, Adhip P N Majumdar, Myoung Jae Kang, Dong Geun Lee, Woo Sung Moon
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Korean J Pathol. 2005;39(6):385-390.
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Abstract
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- BACKGROUND
It has been well demonstrated that the overexpression of epidermal growth factor receptor (EGFR) is associated with numerous gastrointestinal malignancies, including gallbladder carcinoma. However, the cellular events that regulate EGFR in cancer cells have not been fully elucidated. A novel negative regulator of EGFR that is referred to as EGFR related protein (ERRP) has recently been identified. The aim of this study was to investigate the expression and localization of ERRP in gallbladder carcinoma and to examine a possible role for ERRP.
METHODS
We examined the immunohistochemical expressions of ERRP, p53 and proliferating cell nuclear antigen labeling index (PCNA-LI) in formalin-fixed, paraffinembedded specimens of 43 cases of gallbladder carcinoma, 7 cases of adenoma and 3 cases of dysplasia.
RESULTS
In the normal mucosa, ERRP immunoreactivity was positive in over 64% of specimens. In contrast, the ERRP staining was positive in only 46% of the cancer specimens.
The expression of ERRP in cancer cells was inversely correlated with tumor cell proliferation. The loss of ERRP expression correlated with the p53 overexpression.
CONCLUSIONS
Our data indicate that the down-regulation or loss of ERRP could play an important role in the progression of gallbladder carcinoma. The inverse relationship between the ERRP expression and PCNA-LI suggests that ERRP may play a role in the inhibition of tumor cell proliferation in gallbladder cancer.
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