Exosomal Long Non-coding RNA HOTTIP Increases Resistance of Colorectal Cancer Cells to Mitomycin via Impairing MiR-214-Mediated Degradation of KPNA3.

Xijuan Chen,Yan Cheng,Baoxing Liu,Hong Gen,Qinglan Zhang,Yingqiang Liu,Junqi Liu,Yanan Sun,Yonglei Zhang

doi:10.3389/fcell.2020.582723

Abstract

It has been reported that long non-coding RNA HOXA distal transcript antisense RNA (lncRNA HOTTIP) functions as a tumor promoter in colorectal cancer (CRC). Hence, we paid attention to exploring whether exosomes could carry lncRNA HOTTIP to affect the mitomycin resistance in CRC and to identify the underlying mechanisms. High expression of HOTTIP was detected in mitomycin-resistant CRC cells. Inhibition of HOTTIP reduced the mitomycin resistance. In the co-culture system of mitomycin-resistant cells or their derived exosomes with CRC cells, the HOTTIP was found to be transferred into the parental cells via extracellular vesicles (EVs) secreted from mitomycin-resistant cells and to contribute to the mitomycin resistance. Based on the bioinformatics databases, possible interaction network of HOTTIP, microRNA-214 (miR-214) and Karyopherin subunit alpha 3 (KPNA3) in CRC was predicted, which was further analyzed by dual-luciferase reporter, RNA binding protein immunoprecipitation and RNA pull-down assays. As HOTTIP down-regulated miR-214 to elevate the KPNA3 expression, HOTTIP enhanced the mitomycin resistance through impairing miR-214-dependent inhibition of KPNA3. Finally, HOTTIP was suggested as an independent factor predicting mitomycin response in patients with CRC. Those data together confirmed the promotive effects of EV-carried HOTTIP on the mitomycin resistance, while targeting HOTTIP might be a promising strategy overcoming drug resistance in CRC.

Highlights

Colorectal cancer (CRC), most of which initiates from colorectal adenomas, is regarded as one of the frequently occurring cancers and one of the reasons of the death caused by cancer around the world (Dekker and Rex, 2018)
To select mitomycin-resistant cell lines, the seven CRC cell lines were treated with mitomycin, and the two cell lines HCT116 and SW620 with the highest half maximal inhibitory concentration (IC50) were chosen for the following experiments (Figure 1A)
Reverse Transcription-Quantitative Polymerase Chain Reaction (RT-qPCR) showed that the expression of HOXA distal transcript antisense RNA (HOTTIP) in seven CRC cell lines was higher than in normal intestinal epithelial cells, and we found that the expression of HOTTIP in HCT116 and SW620 cells was lower than that in other CRC cell lines (Figure 1F)

Summary

Introduction

Colorectal cancer (CRC), most of which initiates from colorectal adenomas, is regarded as one of the frequently occurring cancers and one of the reasons of the death caused by cancer around the world (Dekker and Rex, 2018). There is still insufficient information about the global prevalence of CRC (Wong et al, 2020). Great improvements have been witnessed in the therapy of CRC such as using drugs including the anti-EGFR monoclonal antibodies cetuximab and panitumumab, as well as the multikinase inhibitor regorafenib and so on (De Mattia et al, 2015). Chemotherapy serves as one of selectable treatment options for patients with metastatic CRC. Mitomycin is a chemotherapeutic agent that shows some modest efficacy at low cost for CRC (Dimou et al, 2010). This study aims to identify the mechanism associated with tumorigenesis and drug resistance in CRC so as to develop novel strategies for cancer prevention

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