The tamoxifen-regulated, long non-coding RNA LINC00992 affects proliferation, migration, and expression of tamoxifen resistance-associated genes in MCF-7 breast cancer cells

Sebastian Graf; Johannes Haybaeck; Gerhard Behre; Thomas Kalinski; Norbert Nass

doi:10.5114/wo.2023.125000

The tamoxifen-regulated, long non-coding RNA LINC00992 affects proliferation, migration, and expression of tamoxifen resistance-associated genes in MCF-7 breast cancer cells

Contemp Oncol (Pozn). 2022;26(4):294-305. doi: 10.5114/wo.2023.125000. Epub 2022 Dec 30.

Authors

Sebastian Graf^{1

2}, Johannes Haybaeck^{3

4}, Gerhard Behre⁵, Thomas Kalinski¹, Norbert Nass^{1

5}

Affiliations

¹ Department of Pathology, Medical Faculty, Otto-von-Guericke University Magdeburg, Magdeburg, Germany.
² Institute of Pathology, Heidelberg University Hospital, Heidelberg, Germany.
³ Diagnostic and Research Center for Molecular BioMedicine, Institute of Pathology, Medical University Graz, Austria.
⁴ Institute of Pathology, Neuropathology and Molecular Pathology, Medical University of Innsbruck, Innsbruck, Austria.
⁵ Dessau Medical Center and Brandenburg Medical School Theodor Fontane (MHB), Department for Internal Medicine I, Dessau, Germany.

Abstract

Introduction: Tamoxifen-adapted MCF-7 breast cancer cells (MCF-7-TAM-R) are a model for acquired tamoxifen resistance in oestrogen receptor-positive breast cancer. In this system, the expression of long-non-coding RNA LINC00992 is decreased. LINC00992 might therefore contribute to tamoxifen adaption and associated gene expres-sion changes. Here, we investigated whether a modulation of LINC00992 modifies gene expression, proliferation, and migration.

Material and methods: Up- and down-- regulation of LINC00992 was performed using plasmid vectors and siRNA. Gene expression was measured via nCounter® and quantitative real-time polymerase chain reaction. Database analysis was performed using GEPIA2 and cBioportal. Furthermore, we performed scratch assays, colony-forming assays, and proliferation assays with MCF-7 and MCF-7-TAM-R after up-regulation of LINC00992.

Results: Up- and down-regulation of LINC00992 caused gene expression changes in 4 of the 42 tamoxifen-regulated genes tested. Especially ubiquitin D, single-minded homologue 1 (SIM1) carcinoembryonic antigen-related cell adhesion molecule 5 and the G-protein coupled oestrogen receptor 1 were affected. In tamoxifen-adapted MCF-7-TAM-R cells, LINC00992 overexpression resulted in augmented viability and proliferation and enhanced migration. Database analyses revealed that luminal breast cancers have increased expression of LINC00992 compared to Her2-type/neu- or basal type. Furthermore, higher expression of LINC00992 was associated with poor prognosis in luminal-A carcinomas.

Conclusions: Changes in the expression of tamoxifen-regulated genes could be induced by manipulating LINC00992's abundance, suggesting that it is at least partially involved in the establishment of the tamoxifen-induced gene expression pattern. LINC00992 may also serve as a prognostic biomarker and may indicate the development of tamoxifen resistance.

Keywords: LINC00992; MCF-7; breast cancer; gene expression analysis; long non-coding RNA; tamoxifen resistance.