Effect of the LncRNA GAS5-MiR-23a-ATG3 Axis in Regulating Autophagy in Patients with Breast Cancer.

BACKGROUND/AIMS: An increasing body of evidence shows that long noncoding RNAs (lncRNAs) are involved in many different cancers. In this study, we aimed to investigate the competing endogenous RNA (ceRNA)-dependent mechanism by which the lncRNA GAS5 contributes to the development of breast cancer.

METHODS

A total of 68 breast cancer patients were enrolled, and breast cancer and adjacent normal tissues were collected. The human breast cancer cell lines MDA-MB-231, MDA-MB-453, BT549, SK-BR-3 and MCF-7 and human breast cell line MCF10A were utilized in this study. Quantitative reverse transcription-polymerase chain reaction (qRT-PCR) and western blotting were performed to detect expression of relative factors. RNA immunoprecipitation (RIP) was used to evaluate the relationship between GAS5 and miR-23a, and a dual luciferase reporter gene assay was employed to assess the relationship between ATG3 and miR-23a. A subcutaneous xenograft nude mouse model was generated to examine the role of GAS5 and its regulatory pathway in autophagy.

RESULTS

GAS5 levels were frequently decreased in breast cancer tissues and cell lines, and its relatively low expression was closely related to a larger tumour size, advanced tumour-node-metastasis (TNM) stage and estrogen receptor-negative (ER-) breast cancer tissues. More importantly, we found that GAS5 promoted autophagy, with enhanced autophagosome formation after GAS5 overexpression. GAS5 was found to act as a microRNA sponge in a pathway that included miR-23a and its target gene ATG3. The GAS5-miR-23a-ATG3 axis significantly regulated autophagy in vivo and in vitro.

CONCLUSIONS

In summary, we report that the GAS5-miR-23a-ATG3 axis can be regarded as a key regulator of autophagy pathways in breast cancer; it may constitute a promising biomarker and therapeutic target in the future.