| 研究実績の概要 |
The main objective is to use drugs/chemical modifiers of intracellular redox signaling, ER stress that induce distinct cell death alone or combined with radiation. Herein, it was found that (CDDO-Me or RTA 402) induced cell death depending on the treatment concentration. CDDO-Me induced paraptosis in HCT-116 colorectal cancer cells at lower concentration by promoting vacuolation that results from the endoplasmic reticulum (ER), without the involvement of mitochondrial mechanism. However, at higher doses it induced apoptosis in similar cell line. Mechanistic investigation revealed that the indigenous level of known paraptosis inhibitor, Alix/AIP-1 was down-regulated by CDDO-Me treatment. Besides, Cycloheximide prevents CDDO-Me-induced vacuolation and cell death, indicating the requirement of active de-novo protein synthesis. ER stress marker BiP and CHOP expression are increased, with CHOP express at earlier time points and its expression is well corelated with induction of ROS and time-dependent increase in intracellular calcium. It suggests CHOP as the main ER protein involved in the CDDO-Me -induced paraptosis.
In addition, in U937 and MOLT-4 cells combined use of romidepsin (FK228) and hyperthermia enhanced cell death. Mechanistic investigation revealed that low doses of FK228 sensitize cell to heat treatment via increased intracellular superoxide generation, increased loss of intracellular GSH, MMP loss and increased intracellular [Ca2+]i.. Interestingly, Fk228 showed more sensitizing effects in the MOLT-4 (p53 wild type) compared to U937 cells (p53 mutant) cells.
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| 現在までの達成度 (区分) |
現在までの達成度 (区分)
2: おおむね順調に進展している
理由
Downregulation of known paraptosis inhibitor, Alix/AIP-1 confirms the induction of paraptosis following CDDO-Me treatment. It was found that CHOP is involved as the key modulator of ER-mediated paraptosis in HCT-116 colorectal cancer cells. Interestingly, in another colorectal cancer HCT-115 cells CDDO-Me does not induced paraptosis. In addition, FK228 enhanced intracellular ROS generation and sensitize cells to hyperthermia treatment. Overall, the research is progressing smoothly, in line with the purpose of research.
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| 今後の研究の推進方策 |
In continuation of last year study, the effect of CDDO-Me on additional colorectal cancer cell lines such as DLD-1, Colo 205, will be investigated. Further the reason for CDDO-Me induced paraptosis or apoptosis in particular colorectal cell line will be explored. Protein expression and siRNA analysis will be performed to identify the specific protein related to induction of paraptosis. In addition, the potential of drugs to enhanced radiation/hyperthermia-induced cancer cell death will be examined. All the obtained results will be summarized and published as a research paper.
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