Relationship between radiosensitivity and Nrf2 target gene expression in human hematopoietic stem cells

Area of Science:

• Hematology
• Molecular Biology
• Radiation Biology

Background:

• NFE2-related factor 2 (Nrf2) is a transcription factor regulating antioxidant genes.
• Hematopoietic stem cells (HSCs) are crucial for blood cell formation and can be affected by radiation.
• Understanding HSC radiosensitivity is vital for stem cell transplantation and radiation therapy.

Purpose of the Study:

• To investigate the expression of Nrf2 target genes in human HSCs following X irradiation.
• To determine the relationship between Nrf2 target gene expression and HSC radiosensitivity.

Main Methods:

• CD34(+) cells from human umbilical cord blood were isolated.
• Cells were exposed to 2-Gy X irradiation.
• mRNA expression of Nrf2 target genes (HO-1, FTH1, NQO1, GSR, TXNRD1) was analyzed.
• Colony-forming capacity of HSCs was assessed.
• Correlation between gene expression and cell survival was evaluated.

Main Results:

• X irradiation significantly reduced HSC colony-forming capacity to about 20% of control.
• mRNA levels of HO-1, FTH1, NQO1, GSR, and TXNRD1 were significantly upregulated post-irradiation.
• A negative correlation was found between HSC survival and baseline NQO1 mRNA expression.
• Low intrinsic NQO1 mRNA levels were associated with radioresistance in HSCs.

Conclusions:

• The Nrf2-associated antioxidant system plays a role in HSC radiosensitivity.
• NQO1 expression may serve as a predictive marker for HSC radioresistance.
• Targeting the Nrf2 pathway could potentially modulate HSC radiosensitivity.