PMID- 34316376 OWN - NLM STAT- PubMed-not-MEDLINE LR - 20220425 IS - 2052-0034 (Print) IS - 2052-0034 (Electronic) VI - 9 IP - 3 DP - 2021 Jun TI - lncRNA-PACER upregulates COX-2 and PGE2 through the NF-kappaB pathway to promote the proliferation and invasion of colorectal-cancer cells. PG - 257-268 LID - 10.1093/gastro/goaa060 [doi] AB - BACKGROUND: p50-associated cyclooxygenase-2 extragenic RNA (PACER) is a recently identified antisense long non-coding RNA (lncRNA) located on the upstream of the promoter region of cyclooxygenase-2 (COX-2). Preliminary studies have suggested that PACER is involved in the regulation of COX-2 expression in macrophagocyte and osteosarcoma cells. However, the role of this lncRNA in colorectal cancer (CRC) remains elusive. Here, we investigated the expression of PACER and its effect on cell proliferation and invasion to explore the role of PACER in CRC. METHODS: Real-time quantitative PCR (RT-qPCR) analysis was used to evaluate the expression of PACER in CRC tissues and cells. Methyl thiazolyl tetrazolium (MTT) analysis was then used to investigate the inhibition effect of PACER knock-down in cell proliferation. The promoting role of this lncRNA on invasion by CRC cells was analysed by wound-healing assays, colony-formation assay, and transwell assays. We then used fluorescence in situ hybridization (FISH) to establish the subcellular localization of PACER. COX-2 protein levels were quantified by Western blot analysis and grayscale scanning analysis following the knock-down of PACER. Luciferase assay was carried out to monitor the modulation of the COX-2 promoter region by PACER. Tumor xenografts models were used to investigate the impact of PACER on the tumorigenesis of CRC cells in vivo. Enzyme-linked immunosorbent assay (ELISA) was then used to quantify prostaglandin E2 (PGE2) production upon knock-down of PACER. RESULTS: RT-qPCR analysis revealed that PACER was highly expressed in CRC tissues and cells, and a high PACER-expression level was associated with poor prognosis. MTT assay, wound-healing assay, colony-formation assay, and transwell assay revealed that PACER enhanced CRC-cell proliferation, invasion, and metastasis in vitro. Analysis of lncRNA localization by FISH showed that it mainly resided in the nucleus. RT-qPCR showed that PACER increased mRNA levels of COX-2. Western blot analysis demonstrated, under normal circumstances, that knock-down of PACER decreased the COX-2 protein level. In the case of p50 absence, COX-2 protein increased rapidly and remained highly expressed after knocking down PACER. Luciferase assay revealed that PACER modulated the COX-2 promoter region. Mouse xenograft models of CRC revealed that PACER promoted colorectal tumorigenesis in vivo. ELISA revealed that PACER knock-down inhibited PGE2 production. CONCLUSIONS: PACER modulates COX-2 expression through the nuclear factor kappa B (NF-kappaB) pathway in CRC. An increased level of PACER enhances proliferation, migration, and invasion of tumor cells by increasing COX-2 and PGE2 synthesis. CI - (c) The Author(s) 2020. Published by Oxford University Press and Sixth Affiliated Hospital of Sun Yat-sen University. FAU - Sun, Peng AU - Sun P AD - Department of Colorectal Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, P. R. China. AD - Department of Gastrointestinal Surgery, Shenzhen Hospital, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Shenzhen, Guangdong, P. R. China. FAU - Quan, Ji-Chuan AU - Quan JC AD - Department of Colorectal Surgery, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China. FAU - Wang, Song AU - Wang S AD - Department of Colorectal Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, P. R. China. FAU - Zhuang, Meng AU - Zhuang M AD - Department of Colorectal Surgery, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China. FAU - Liu, Zheng AU - Liu Z AD - Department of Colorectal Surgery, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China. FAU - Guan, Xu AU - Guan X AD - Department of Colorectal Surgery, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China. FAU - Wang, Gui-Yu AU - Wang GY AD - Department of Colorectal Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, P. R. China. FAU - Wang, Hong-Ying AU - Wang HY AD - Department of State Key Laboratory of Molecular Oncology, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China. FAU - Wang, Xi-Shan AU - Wang XS AD - Department of Colorectal Surgery, The Second Affiliated Hospital of Harbin Medical University, Harbin, Heilongjiang, P. R. China. AD - Department of Colorectal Surgery, National Cancer Center/Cancer Hospital, Chinese Academy of Medical Sciences and Peking Union Medical College, Beijing, P. R. China. LA - eng PT - Journal Article DEP - 20201210 PL - England TA - Gastroenterol Rep (Oxf) JT - Gastroenterology report JID - 101620508 PMC - PMC8309685 OTO - NOTNLM OT - colorectal cancer (CRC) OT - cyclooxygenase-2 (COX-2) OT - lncRNA OT - p50-associated cyclooxygenase-2 extragenic RNA (PACER) EDAT- 2021/07/29 06:00 MHDA- 2021/07/29 06:01 PMCR- 2020/12/10 CRDT- 2021/07/28 06:32 PHST- 2020/02/10 00:00 [received] PHST- 2020/04/06 00:00 [revised] PHST- 2020/06/08 00:00 [accepted] PHST- 2021/07/28 06:32 [entrez] PHST- 2021/07/29 06:00 [pubmed] PHST- 2021/07/29 06:01 [medline] PHST- 2020/12/10 00:00 [pmc-release] AID - goaa060 [pii] AID - 10.1093/gastro/goaa060 [doi] PST - epublish SO - Gastroenterol Rep (Oxf). 2020 Dec 10;9(3):257-268. doi: 10.1093/gastro/goaa060. eCollection 2021 Jun.