Epstein-Barr virus efficiently immortalizes human B cells without neutralizing the function of p53

Area of Science:

• Virology
• Cell Biology
• Cancer Research

Background:

• Epstein-Barr virus (EBV) immortalizes human B cells into lymphoblastoid cell lines (LCLs).
• EBV-infected LCLs express latent viral genes, influencing cellular responses.
• Understanding B cell response to DNA damage is crucial for cancer research.

Purpose of the Study:

• To investigate the DNA damage response in EBV-immortalized B cells (LCLs).
• To compare the response of LCLs and primary B cells to genotoxic agents.
• To elucidate the role of p53 and pRb in EBV-driven B cell immortalization and drug sensitivity.

Main Methods:

• Treatment of LCLs and primary B cells with cisplatin, a DNA-damaging agent.
• Analysis of tumor suppressor protein p53, mdm2, WAF1/p21, Bcl2, and Bax mRNA levels.
• Assessment of retinoblastoma gene product (pRb) phosphorylation status.
• Over-expression of wild-type p53 in LCLs.

Main Results:

• LCLs showed high sensitivity to cisplatin, with rapid p53 accumulation and apoptosis.
• Primary B cells and mitogen-activated B cells exhibited p53 induction but underwent growth arrest, not apoptosis.
• EBV infection induced p53 expression in B cells.
• Over-expression of p53 in LCLs led to apoptosis, preceded by pRb dephosphorylation.

Conclusions:

• EBV-immortalized B cells (LCLs) are sensitized to the p53-mediated DNA damage response.
• Unlike normal B cells, LCLs undergo apoptosis rather than growth arrest when treated with genotoxic agents due to EBV-driven proliferation.
• EBV-induced B cell transformation leads to a heightened sensitivity to DNA-damaging agents, resulting in apoptosis.