Long non‑coding RNA growth arrest‑specific 5 (GAS5) acts as a tumor suppressor by promoting autophagy in breast...

Area of Science:

• Molecular Oncology
• Cellular Biology
• Cancer Research

Background:

• Growth arrest-specific 5 (GAS5) is recognized as a tumor suppressor, inhibiting cell survival and malignancy across various cancer types.
• Unc-51 like autophagy activating kinase (ULK)1/2 are crucial regulators of autophagy initiation.
• The interplay between GAS5 and ULK1/2 in breast cancer (BC) pathogenesis requires elucidation.

Purpose of the Study:

• To investigate the correlation between GAS5 and ULK1/2 in breast cancer.
• To determine the role of GAS5 in regulating breast cancer cell proliferation, invasion, and tumor formation.
• To explore the mechanisms underlying GAS5's tumor suppressive functions, including autophagy-dependent and independent pathways.

Main Methods:

• Quantitative analysis of GAS5 and ULK1/2 expression in clinical BC samples using reverse transcription-quantitative PCR.
• In vitro studies using MCF-7 cells involving overexpression of GAS5, cell cycle analysis, apoptosis assays (Annexin V-FITC/PI), Transwell invasion assays, and western blotting.
• Pharmacological inhibition of autophagy using 3-methyladenine (3-MA) to dissect GAS5's mechanisms of action.

Main Results:

• GAS5 was downregulated in BC samples and positively correlated with ULK1/2 expression.
• Overexpression of GAS5 in MCF-7 cells upregulated ULK1/2, inhibited proliferation and invasion, and reduced tumor formation, effects partially reversed by 3-MA.
• GAS5 overexpression enhanced chemoresistance to cisplatin in an autophagy-independent manner.

Conclusions:

• GAS5 contributes to breast cancer pathogenesis, potentially by promoting autophagy.
• The tumor suppressive effects of GAS5 are, in part, mediated by autophagy induction.
• GAS5 exhibits autophagy-independent mechanisms for promoting chemosensitivity, which warrant further investigation.