Knockdown of MiR-20a Enhances Sensitivity of Colorectal Cancer Cells to Cisplatin by Increasing ASK1 Expression

Abstract

Background/Aims: Platinum-based chemotherapy is one of the most important strategies for treatment of colorectal cancer. To improve the therapeutic efficiency, adjuvant drugs were sought to sensitize colorectal cancer cells to platinum-based agents such as cisplatin. As previous research has shown that miRNAs are associated with chemosensitivity, we aimed to alter miRNA regulation in colorectal cancer cells to increase their chemosensitivity. Methods: MTT assays were performed to determine the viability of HT29, SW480, and LoVo cells. Quantitative real time polymerase chain reaction (qRT-PCR) was performed to examine the expression of miR-20a in these cell lines. Regulation of the miR-20a/ASK1 axis was confirmed by western blotting and luciferase reporter assays. After treatment with miR-20a inhibitor (anti-miR-20a) and cisplatin, production of reactive oxygen species (ROS), mitochondrial membrane potential, and apoptosis were measured by flow cytometry. Activation of ASK1, Bcl-xl, JNK, and caspase-9, -7, and -3 was detected by western blotting. Results: miR-20a was overexpressed in colorectal cancer cell lines. Furthermore, knockdown of miR-20a increased the sensitivity of colorectal cancer cells to cisplatin treatment in vitro and in vivo. We demonstrated that the ASK1 gene was the target of miR-20a, and knockdown of miR-20a increased the expression of ASK1 in colorectal cancer cells. As cisplatin treatment induced production of ROS, knockdown of miR-20a enhanced ROS signaling through promoting the phosphorylation of ASK1. Phosphorylation of JNK and the subsequent mitochondrial apoptosis were triggered by the combination of cisplatin and anti-miR-20a. Conclusions: Knockdown of miR-20a enhanced sensitivity of colorectal cancer cells to cisplatin through the ROS/ASK1/JNK pathway.

<p>Restoration of miR-26b expression partially reverses the cisplatin resistance of NSCLC by targeting tafazzin</p>

“…Recent studies have demonstrated that formation of cisplatin resistance is partially induced by dysregulation of miRNAs in cancers including NSCLC. [24][25][26] MiRNAs have been considered as potential targets for improving the cisplatin-based treatment. Among these cancer-related miRNAs, miR-26b acts as a tumor suppressor and is always downregulated in multiple cancers.…”

Function and mechanisms of microRNA‑20a in colorectal cancer (Review)

“…Furthermore, miRNAs are associated with the expression of a number of target genes that are related to chemosensitivity or the sensitivity of drugs to cancer cells (110). Therefore, identifying an indicator to monitor CRC chemotherapy is important and recent studies have indicated that miR-20a can be used as a monitoring indicator for chemotherapy (111,112). miR-20a is differentially expressed before and after chemotherapy.…”

“…However, the chemotherapy resistance of CRC cells is challenge in the treatment of patients with CRC (119). Studies have indicated that miR-20a induces cisplatin resistance in numerous cancers, potentially including in CRC (55,57,111,112). The miR-20a inhibitor can sensitize cisplatin-induced CRC cytotoxicity via the reactive oxygen species (ROS) pathway.…”

“…Therefore, cisplatin-induced mitochondrial apoptosis is promoted by the ROS/ASK1/JNK pathway through combination with anti-miR-20a in CRC. Furthermore, the introduction of an miR-20a inhibitor eliminates cisplatin resistance and enhances the anti-tumor effect of cisplatin in vivo (112).…”

“…The early detection and treatment of CRC is important for controlling the progression of the disease. A number of studies have demonstrated that miRNA can be used as a biomarker for the diagnosis and prognosis of CRC, and this can provide information on tumor initiation, development, invasion, metastasis and response to chemotherapy (16,39,111,112,122,123). A number of studies have also confirmed that miR-20a is significantly upregulated and serves an important role in the development, progression and therapeutic response of CRC, and it can be used as a biomarker for CRC in tissues, serum and fecal samples (124).…”