Glutathione S-transferase-π overexpression is closely associated with K-ras mutation during human colon carcinogenesis
| Autor: | Koji Miyanishi, Tetsuji Takayama, Takaharu Nakajima, Yoshiro Niitsu, Sumio Sakamaki, Katsuhisa Kogawa, Atsushi Nobuoka, Motoh Ohi, Junji Kato, Tsuyoshi Hayashi, Rishu Takimoto |
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| Předmět: |
Adenoma
Transcription Genetic Molecular Sequence Data Enzyme-Linked Immunosorbent Assay Colorectal adenoma Biology Transfection medicine.disease_cause Gene Expression Regulation Enzymologic Tumor Cells Cultured medicine Humans Electrophoretic mobility shift assay RNA Messenger Promoter Regions Genetic Glutathione Transferase Base Sequence Hepatology Reverse Transcriptase Polymerase Chain Reaction Carcinoma Gastroenterology medicine.disease Molecular biology Isoenzymes Reverse transcription polymerase chain reaction Genes ras Placental alkaline phosphatase Real-time polymerase chain reaction Glutathione S-Transferase pi Colonic Neoplasms Mutation Cancer research Colorectal Neoplasms Carcinogenesis Polymorphism Restriction Fragment Length Aberrant crypt foci |
| Zdroj: | Scopus-Elsevier |
| Popis: | Background & Aims: In colorectal adenoma and carcinoma, glutathione S-transferase-π (GSTP1-1) is highly expressed. K- ras mutation is also known to occur frequently in colorectal adenoma and carcinoma, as well as in the putative precursor of adenoma, aberrant crypt foci (ACF). Further, forced expression of v-H- ras in rat liver epithelial cells has been shown to enhance rat π-class GST expression. The aim of the present study is, therefore, to investigate the causative relationship between GSTP1-1 overexpression and K- ras mutation in these lesions. Methods: Twenty-seven specimens of colorectal carcinoma, 24 of adenoma, and 28 of ACF were examined in this study. The expression of GSTP1-1 or p21 K-ras was examined by immunohistochemistry. The GSTP1-1 messenger RNA levels were measured by TaqMan reverse-transcription polymerase chain reaction (PCR). K- ras mutation was detected by two-step PCR restriction fragment length polymorphism. v-K- ras transfection to RPMI-4788 colon carcinoma cells was carried out by the lipofection method. Activities of GSTP1-1 promoters containing AP-1 and Sp1 responsive elements in the v-K- ras transfectants were measured by a secreted form of human placental alkaline phosphatase (SEAP) assay. Nuclear protein from these transfectants bound to the GSTP1-1 promoter was analyzed by electrophoretic mobility shift assay (EMSA). Results: In human colorectal carcinoma, adenoma, and ACF, close association of increased expression of GSTP1-1 with K- ras mutation was observed. v-K- ras transfectants showed significantly higher SEAP activity than that of mock-transfectant activity. EMSA showed specific interaction of AP-1 with promoter of GSTP1-1 . Conclusions: It is highly plausible that GSTP1-1 overexpression in ACF, colorectal adenoma, and carcinoma is induced by K- ras mutation via AP-1 activation. GASTROENTEROLOGY 2001;121:865-874 |
| Databáze: | OpenAIRE |
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