Sequencing of human breast cancer cell line MDA-MB-231 and its highly pulmonary metastatic subline MDA-MB-231-LM2

Purpose: Tumor metastasis is the main cause of death from breast cancer patients and cell migration plays a critical role in metastasis. Recent studies have shown long non-coding RNAs (lncRNAs) play an essential role in the initiation and progression of cancer. In the present study, the role of a LncRNA, Rho GTPase Activating Protein 5- Antisense 1 (ARHGAP5-AS1) in breast cancer was investigated. Methods: RNA sequencing was performed to find out dysregulated LncRNAs in MDA-MB-231-LM2 cells. Transwell migration assays and F-actin staining were utilized to estimate cell migration ability. RNA pulldown assays and RNA immunoprecipitation were used to prove the interaction between ARHGAP5-AS1 and SMAD7. Western blot and immunofluorescence imaging were used to examine the protein levels. Dual luciferase reporter assays were performed to evaluate the activation of TGF-β signaling. Results: Compared to MDA-MB-231 cells, the expression of LncRNA ARHGAP5-AS1 (NR_027263) was significantly suppressed in its highly metastatic subtype MDA-MB-231-LM2 cells. Functional study showed ARHGAP5-AS1 could inhibit cell migration via suppression of stress fibers in breast cancer cell lines. Afterwards, SMAD7 was further identified to interact with ARHGAP5-AS1 by its PY motif and thus its ubiquitination and degradation was blocked due to reduced interaction with E3 ligase SMURF1 and SMURF2. Moreover, ARHGAP5-AS1 could inhibit TGF-β signaling pathway due to its inhibitory role on SMAD7. Conclusion: Overall, these findings demonstrate that ARHGAP5-AS1 inhibits breast cancer cell migration and could serve as a novel biomarker for breast cancer metastasis and a potent target for the treatment in the future. Whole RNA profiles of MDA-MB-231 and MDA-MB-231-LM2 cells.