MicroRNA-138 modulates DNA damage response by repressing histone H2AX expression

Area of Science:

• Molecular Biology
• Genetics
• Cancer Biology

Background:

• Precise regulation of DNA damage response is critical for cellular survival and preventing genomic instability in cancer.
• Phosphorylated histone H2AX (γH2AX) foci formation is a hallmark of DNA damage sites and facilitates repair.
• The role of microRNAs (miRNAs) in modulating DNA damage response pathways remains largely unexplored.

Purpose of the Study:

• To identify miRNAs that regulate the DNA damage response.
• To elucidate the mechanism by which specific miRNAs impact DNA repair and genomic stability.
• To explore the therapeutic potential of identified miRNAs in cancer treatment.

Main Methods:

• Development of a cell-based screening assay using ionizing radiation (IR)-induced γH2AX foci in U2OS cells.
• Screening of a human miRNA mimic library to identify inhibitors of γH2AX foci formation.
• Molecular analysis of miR-138 targeting of histone H2AX, its effect on gene expression, homologous recombination, and cellular sensitivity to DNA-damaging agents.

Main Results:

• Several miRNAs were identified that inhibit IR-induced γH2AX foci formation.
• miR-138 was found to directly target the histone H2AX 3'-untranslated region, reducing H2AX expression.
• Overexpression of miR-138 led to chromosomal instability, inhibited homologous recombination, and increased sensitivity to DNA-damaging agents (cisplatin, camptothecin, IR).

Conclusions:

• miR-138 acts as a regulator of genomic stability by modulating the DNA damage response pathway.
• miR-138 enhances the efficacy of DNA-damaging agents, suggesting its potential as a therapeutic agent in cancer treatment.
• Restoring histone H2AX expression can attenuate the effects of miR-138 on cellular sensitivity to chemotherapy.