Analysis of chemo-resistant mechanism through DCK promotor demethylation and establishment of its prevention

2019 Fiscal Year Final Research Report

• Project/Area Number: 17K10117
• Research Category: Grant-in-Aid for Scientific Research (C)
• Allocation Type: Multi-year Fund
• Section: 一般
• Research Field: Pediatrics
• Research Institution: Kagoshima University
• Principal Investigator: Okamoto Yasuhiro 鹿児島大学, 医歯学域医学系, 准教授 (30398002)
• Project Period (FY): 2017-04-01 – 2020-03-31
• Keywords: ネララビン / 耐性 / 急性リンパ性白血病 / T細胞

Outline of Final Research Achievements

CCRF-CEM cells were incubated with nelarabine by the limiting dilution method and two nelarabine-resistant clones were established. The resistant clones had higher IC50 (55 and 78 times higher) than the parent clone in the MTT assay. The expressions of ENT1, DCK, and DGuoK mRNAs associated with nelarabine metabolism were significantly down-regulated in resistant clones; demethylation of the promoter region of DCK was not involved. The resistant clones showed increased expression of p-Akt, suggesting increased expression of the PI3K/AKT pathway. In addition, p-ERK hyperactivation was observed after 72 hours of nelarabine treatment. Overactivation of the MEK/ERK pathway specific to the nelarabine metabolic pathway was thought to be the cause of resistance.

Free Research Field

小児がん

Academic Significance and Societal Importance of the Research Achievements

本研究は、ネララビンの薬剤耐性獲得の機序を明らかにした。つまりネララビン投与によって、ネララビン代謝に関連する遺伝子の発現が変化し、代謝経路に特異的なMEK/ERK経路の過剰活性化によってアポトーシスが起らなくなっていた。このような変化は、ネララビンとの共培養で、短時間に、しかも高頻度に起こっていた。難治性のT 細胞性腫瘍のほとんどがいずれネララビン耐性を獲得するが、本研究の成果によって、実際の患者におけるネララビン投与において、どのようなdose scheduleで行えば耐性化をより予防できるかがわかり、重要な知見である。