A regulatory network comprising let-7 miRNA and SMUG1 is associated with good prognosis in ER+ breast tumours

Area of Science:

• Molecular Biology
• Cancer Research
• Genetics

Background:

• Single-strand selective uracil-DNA glycosylase 1 (SMUG1) initiates base excision repair (BER) and is linked to cancer risk and treatment.
• SMUG1's role in cancer is complex, involving functions beyond BER, such as RNA quality control.

Purpose of the Study:

• To investigate novel SMUG1 interaction partners and their relevance to cancer development and treatment.
• To explore the hypothesis that SMUG1's primary function in cancer involves processes other than BER.
• To define a prognostic signature for SMUG1 in breast cancer and identify its regulatory mechanisms.

Main Methods:

• Identification of SMUG1 interaction partners.
• Mapping of the SMUG1 interaction network to define a prognostic signature.
• Correlation analysis of SMUG1 and hsa-let-7b-5p microRNA expression.
• Investigation of the regulatory loop between SMUG1 and hsa-let-7b-5p in MCF7 cells.

Main Results:

• Several novel SMUG1 interaction partners involved in cancer-relevant processes were identified.
• A SMUG1-associated gene network was defined, with high expression correlating with poor prognosis in ER+ breast cancer.
• hsa-let-7b-5p microRNA was identified as an upstream regulator of the SMUG1 interactome.
• Negative correlation between SMUG1 and hsa-let-7b-5p expression and an inhibitory auto-regulatory loop were observed in breast cancer cells.

Conclusions:

• SMUG1 functions within a gene regulatory network impacting cancer cell survival and treatment response.
• SMUG1's role in cancer extends beyond its canonical DNA repair function.
• hsa-let-7b-5p microRNA plays a significant role in regulating SMUG1's function and its impact on breast cancer.