Paclitaxel exposure downregulates miR-522 expression and its downregulation induces paclitaxel resistance in ovarian cancer cells

Mayuko Miyamoto,Koji Nakamura,Akihiko Yoshimura,Misa Yamamoto,Michiko Kodama,Kyoso Ishida,Masaki Kobayashi,Kenjiro Sawada,Kae Hashimoto,Aasa Shimizu,Tadashi Kimura

doi:10.1038/s41598-020-73785-8

Mayuko Miyamoto, Koji Nakamura + Show 9 more

Open Access

https://doi.org/10.1038/s41598-020-73785-8

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Abstract

Paclitaxel resistance is a critical challenge in ovarian cancer treatment. This study aimed to identify microRNAs (miRNAs) that modulate paclitaxel resistance for use as potential therapeutic targets in such settings. Paclitaxel-resistant cell lines were established using two ovarian cancer cell lines: SKOV3ip1 and HeyA8. The evaluation of miRNA polymerase chain reaction (PCR) arrays indicated that the expression of miR-522-3p was downregulated in paclitaxel-resistant cells. The restoration of miR-522-3p sensitized the resistant cells to paclitaxel, and its downregulation desensitized the parental cells. Using PCR arrays, we focused on E2F2, with the luciferase reporter assay revealing that it was a direct target for miR-522-3p. The paclitaxel-resistant cells showed stronger E2F2 expression than the parental cells, while E2F2 inhibition sensitized the resistant cells to paclitaxel. Forced E2F2 expression in the parental cells led to the acquisition of paclitaxel resistance, while miR-522-3p inhibited E2F2 expression and was associated with retinoblastoma protein phosphorylation attenuation, which resulted in G0/G1 arrest. The effects of miR-522-3p and E2F2 in ovarian cancer were examined using public databases, revealing that low miR-522-3p expression and high E2F2 expression were associated with significantly poorer overall survival. In conclusion, miR-522-3p attenuated the degree of paclitaxel resistance in vitro through the downregulation of E2F2; miR-522-3p supplementation may be a therapeutic target for paclitaxel-resistant ovarian cancer.

Highlights

Ovarian cancer is the most lethal gynecological malignancy and was the fifth leading cause of cancer-related death among American women in 2 0181
Validation analyses based on miRNA reverse transcription polymerase chain reaction (RT-PCR) revealed that the expression of miR-522-3p and miR-19410 was significantly downregulated (Fig. 1D), while that of the others was not
Since the miR-522-3p expression level in the paclitaxel-resistant cells was drastically lower than that in the parental cells (SKOV3ip1-partial response (PR); 0.009-fold, HeyA8-PR; 0.08-fold), we focused on miR-522-3p in this study

Summary

Introduction

Ovarian cancer is the most lethal gynecological malignancy and was the fifth leading cause of cancer-related death among American women in 2 0181. Standard therapies for ovarian cancer include cytoreductive surgery and intensive adjuvant chemotherapy using a combination of taxane and platinum. Despite these multimodal treatments, patients with advanced-stage disease (approximately 70% of all cases) eventually experience recurrence, and the 5-year survival rate remains at 30%, without any dramatic improvements over the last 20 y ears[1]. A recent review identified a list of miRNAs (miR-27a, miR-182, miR-663, miR-31, and miR-106a) that may be related to paclitaxel r esistance[8] Based on these concepts, we aimed to identify miRNAs that modulate paclitaxel resistance in vitro, and perform preliminary analyses of their potential as therapeutic targets

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