LINC01770 Is Associated with Stem-like Features and Aggressive Traits in Breast Cancer Cells Through a Putative miR-335-5p/OCT4 Axis.

Background/

Objectives

Long non-coding RNAs (lncRNAs) are regulatory transcripts that contribute to diverse cellular processes and are increasingly recognized for their involvement in human diseases including cancer. In this context, long intergenic non-protein-coding RNA 1770 (LINC01770), also known as RRFERV, has been involved in nasopharyngeal cancer progression. However, its role in breast cancer (BC) remains unexplored. Here, we propose that LINC01770 plays a pivotal role in the development of aggressiveness traits such as invasion, migration, stemness, and tumorigenesis in BC cells.

Methods

The LINC01770 overexpression was performed in BC cells using lentiviral transduction. Stemness and epithelial-mesenchymal transition markers, CD133+/44+ populations, cell migration, cell invasion, tumorigenesis in vitro, and chemoresistance were subsequently assessed via quantitative reverse transcription polymerase chain reaction (RT-qPCR), flow cytometry, Boyden chambers, soft agar, and 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) assays, respectively. LINC01770 expression in BC tissues and mechanistic analyses were performed in silico.

Results

LINC01770 promotes cell migration and invasion accompanied by increased expression of EMT-associated genes. Moreover, elevated LINC01770 levels lead to an expansion of CD133+/CD44+ cell populations and upregulation of stemness-related genes as well as increase tumorigenic capacity in vitro. In contrast, no significant effects on drug resistance were observed. Finally, bioinformatic analyses suggest a putative LINC01770/miR-335-5p/OCT4 regulatory axis, consistent with the observed increase in OCT4 expression after LINC01770 overexpression.

Conclusions

Our findings demonstrate that LINC01770 drives BC progression by promoting migration, invasion, and stemness features via the miR-335-5p/OCT4 axis. To our knowledge, this is the first study identifying LINC01770 as a potential therapeutic target in BC.