lncRNA GAS5 inhibits malignant progression by regulating macroautophagy and forms a negative feedback regulatory loop...

Area of Science:

• Molecular Biology
• Oncology
• Genetics

Background:

• Long non-coding RNA growth arrest specific 5 (GAS5) influences cancer by modulating microRNAs.
• The precise role of GAS5 in colorectal cancer (CRC) progression and its interaction with other pathways remain largely unelucidated.
• Understanding these interactions is crucial for developing targeted therapies.

Purpose of the Study:

• To investigate the role of the GAS5/miR-34a axis and the mammalian target of rapamycin/sirtuin 1 (mTOR/SIRT1) pathway in colorectal cancer.
• To elucidate the feedback loop mechanism involving GAS5, miR-34a, and the mTOR/SIRT1 pathway in regulating macroautophagy and apoptosis in CRC.
• To determine the functional impact of this regulatory network on CRC cell survival and progression.

Main Methods:

• Quantitative reverse transcription polymerase chain reaction (qRT-PCR) to assess expression levels of GAS5, miR-34a, SIRT1, and mTOR in CRC tissues and cell lines.
• Bioinformatic analysis to predict downstream targets of GAS5.
• Luciferase assays and western blotting to confirm miR-34a as a direct target of GAS5.
• Flow cytometry, transmission electron microscopy, and western blotting to evaluate apoptosis, macroautophagy, and the mTOR/SIRT1 pathway.

Main Results:

• GAS5 was found to be downregulated in CRC and functions as a molecular sponge for miR-34a.
• miR-34a was identified as a downstream target of GAS5, mediating the regulation of macroautophagy and inducing apoptosis via the mTOR/SIRT1 pathway.
• A negative feedback loop was established where the mTOR signaling pathway suppresses GAS5 expression, creating a regulatory circuit with miR-34a.
• This GAS5/miR-34a/SIRT1/mTOR feedback loop maintains CRC cells in an equilibrium state, promoting an anti-apoptotic phenotype and contributing to CRC progression.

Conclusions:

• The GAS5/miR-34a axis plays a significant role in colorectal cancer progression by modulating apoptosis and macroautophagy.
• The interplay between GAS5, miR-34a, and the mTOR/SIRT1 pathway forms a crucial negative regulatory feedback loop in CRC.
• This regulatory network contributes to CRC cell survival by maintaining an anti-apoptotic state, highlighting potential therapeutic targets.