Phosphorylation of protein phosphatase 2A facilitated an early stage of chemical carcinogenesis
| Autor: | Takehiko Nohmi, Kumiko Ogawa, Aki Kijima, Ken Kuroda, Shinji Takasu, Yuh Yokoo, Takashi Umemura, Yuji Ishii, Kohei Matsushita |
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| Rok vydání: | 2017 |
| Předmět: |
Male
0301 basic medicine Time Factors Cellular differentiation Phosphatase Allylbenzene Derivatives Apoptosis Anisoles Biology Toxicology medicine.disease_cause Histones DNA Adducts 03 medical and health sciences medicine Animals Protein Phosphatase 2 Phosphorylation Extracellular Signal-Regulated MAP Kinases Protein kinase B PI3K/AKT/mTOR pathway Cell Proliferation Pharmacology Dose-Response Relationship Drug Cell growth Liver Neoplasms Protein phosphatase 2 MAP Kinase Kinase Kinases Phosphoproteins Molecular biology Rats Inbred F344 Cell Transformation Neoplastic src-Family Kinases 030104 developmental biology Mutation Hepatocytes Cancer research Rad51 Recombinase Rats Transgenic Tumor Suppressor Protein p53 Carcinogenesis Proto-Oncogene Proteins c-akt Signal Transduction |
| Zdroj: | Toxicology and Applied Pharmacology. 336:75-83 |
| ISSN: | 0041-008X |
| DOI: | 10.1016/j.taap.2017.10.009 |
| Popis: | Protein phosphatase 2A (PP2A) is a serine-threonine phosphatase that regulates cell signaling pathways. Its inactivation is correlated with tumor malignancy, possibly due to the effects on cell differentiation and malignant cell transformation. Therefore, it has been noted that PP2A could be a promising target for cancer therapy. In our previous study of the hepatocarcinogen estragole (ES), cell proliferation may be required to convert ES-specific DNA adducts to mutations. To explore the trigger for cell proliferation, gpt delta rats were administered ES by gavage at doses of 3, 30 and 300mg/kg/day for 4weeks. ES-induced cell proliferation and gene mutations were observed at only the high dose whereas ES-specific DNA adducts were detected in a dose-dependent manner. Western blot analyses revealed activation of the Akt and ERK pathways without activation of upstream regulators, such as c-Raf, PKC and, PI3K. Phosphorylation of the PP2A C subunit at Tyr307 was found along with phosphorylation of Src. The overall data might imply that PP2A inactivation is responsible for cell cycle progression through activation of the Akt and ERK pathways at high doses of ES. Based on γ-H2AX immunohistochemistry and Western blot analysis for Rad51 protein, the resultant mutation spectra showed large deletion mutations that might result from double strand breaks of DNA. Thus, it is likely that inactivation of PP2A resulted in acceleration and exacerbation of gene mutations. We conclude that PP2A might contribute to an early stage of chemical carcinogenesis, suggesting that PP2A could be a molecular target of primary cancer prevention. |
| Databáze: | OpenAIRE |
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