Blocking MAPK/ERK pathway sensitizes hepatocellular carcinoma cells to temozolomide via downregulating MGMT expression

作者：Qiang Li, Bingjie Ren, Qi Gui, Jing Zhao, Mengyao Wu, Meng Shen, Dapeng Li, Daoming Li, Kai Chen, Min Tao, Rongrui Liang · 发表于：Annals of Translational Medicine · 年份：2020 · DOI：10.21037/atm-20-5478 · 被引用次数：22 · 研究领域：Melanoma and MAPK Pathways、PI3K/AKT/mTOR signaling in cancer、Liver physiology and pathology

BACKGROUND: Hepatocellular carcinoma (HCC) is the fourth most common malignant tumor in China. Temozolomide (TMZ) is a common chemotherapy drug which can effectively kill HCC cells in vitro. However, it is possible that HCC cells possess intrinsic resistance to TMZ. A key mechanism of TMZ resistance is the overexpression of O6-methylguanine-DNA methyltransferase (MGMT). Studies have shown that MAPK may be related to MGMT expression, U0126 is a highly selective inhibitor of MEK1 and MEK2, which were crucial molecule in cascade of mitogen-activated protein kinase/extracellular signal regulated kinase (MAPK/ERK) pathway. Sorafenib was another widely applicated target drug in HCC which could inhibit multiple kinases including MAPK/ERK. This research was aimed to investigate the efficacy of MAPK/ERK inhibitor U0126 and sorafenib combine with TMZ in the treatment of HCC. METHODS: In HCC cells, MAPK/ERK signaling pathway was blocked by U0126 and sorafenib. The effect of blocking MAPK/ERK signaling pathway on TMZ-induced cytotoxicity was evaluated by MTT assay, flow cytometry and TUNEL assay. DNA damage protein and the expression of MGMT were detected by Western-blot. After the downregulation of MAPK/ERK signaling pathway, MGMT mRNA expression and the protein expression of MGMT were quantified by quantitative real-time polymerase chain reaction (RT-qPCR) and immunofluorescence assay, respectively. HepG2 cells were transfected with an MGMT over expression plasmid. After transfection, ...