miR-144-3p/miR-451a promotes lymphovascular invasion through repression of PTEN/p19 in rectal neuroendocrine tumors

Background and Aim: Although rectal neuroendocrine tumor (NET-G1) have potential metastatic capability, even among small tumors, no predictive biomarker for invasion and metastasis has been reported. We analyzed microRNA (miRNA) expression profiles in rectal NET-G1 tissues with and without lymphovascular invasion (LVI). Moreover, we then investigated their target genes to clarify the mechanism of invasion/metastasis in NET-G1.
Methods: miRNA array analysis was performed using 7 rectal NET-G1 tissues with LVI and 7 without LVI. miRNA expression was confirmed by quantitative real-time PCR. A NET cell line H727 was transfected with miRNA mimic or target gene small interfering RNA, and migration and invasion assays were performed.
Results: The expression levels of miR-144-3p and miR-451a were significantly higher in NET-G1 with LVI versus without LVI, as determined by miRNA array analysis and RT-qPCR. A significant correlation was observed between miR-144-3p and miR-451a expression levels, strongly suggesting miR144/451 cluster overexpression in NET-G1 with LVI. Bioinformatic analysis of target genes revealed that miR-144-3p and miR-451a directly interact with PTEN and p19 mRNA, respectively. Immunohistochemistry revealed significantly lower expression of PTEN and p19 in NET-G1 tissues with LVI than in those without LVI. The miR-144-3p and miR-451a mimic significantly increased cell migration/invasion capability, respectively. Knockdown of PTEN and p19 induced significant augmentation of cell invasion and migration capability, respectively.
Conclusions: Our data suggest that overexpression of miR-144/miR-451 cluster promotes LVI via repression of PTEN and p19 in rectal NET-G1 cells. miR-144/451 cluster may be a novel biomarker for predicting invasion/metastasis in rectal NET-G1.

内容要旨・審査要旨・論文本文の公開
本論文は，著者Noriaki Murayamaの学位論文として提出され，学位審査・授与の対象となっている。

This is the peer reviewed version of the following article: Murayama, N., Okamoto, K., Nakagawa, T., Miyoshi, J., Nishida, K., Kawaguchi, T., Kagemoto, K., Kitamura, S., Ma, B., Miyamoto, H., Muguruma, N., Yano, M., Tsuneyama, K., Fujimori, T., Sato, Y., and Takayama, T. (2022) miR-144-3p/miR-451a promotes lymphovascular invasion through repression of PTEN/p19 in rectal neuroendocrine tumors. Journal of Gastroenterology and Hepatology, 37: 919– 927., which has been published in final form at https://doi.org/10.1111/jgh.15833. This article may be used for non-commercial purposes in accordance with Wiley Terms and Conditions for Use of Self-Archived Versions. This article may not be enhanced, enriched or otherwise transformed into a derivative work, without express permission from Wiley or by statutory rights under applicable legislation. Copyright notices must not be removed, obscured or modified. The article must be linked to Wiley’s version of record on Wiley Online Library and any embedding, framing or otherwise making available the article or pages thereof by third parties from platforms, services and websites other than Wiley Online Library must be prohibited.