[EFFECT OF ANTI-CANCER DRUG DOXORUBICINE ON CYTOMEGALOVIRUS INFECTED HUMAN FIBROBLASTS]

Area of Science:

• Cell Biology
• Virology
• Pharmacology

Background:

• Doxorubicin (DOX) is a potent anticancer drug but exhibits significant toxicity to normal cells.
• The mechanisms underlying DOX-induced normal cell death and strategies to mitigate this toxicity remain incompletely understood.
• The role of the p73 protein, a p53 family member, in DOX-treated cells, especially in the context of viral infections, is largely unexplored.

Purpose of the Study:

• To investigate the impact of DOX on normal human fibroblasts.
• To determine if Cytomegalovirus (CMV)-induced anti-apoptotic mechanisms can reduce DOX toxicity.
• To evaluate the involvement of p73 protein isoforms (TAp73 and dNp73) in regulating cell death in CMV-infected, DOX-treated cells.

Main Methods:

• Cell culture of human embryonic lung fibroblasts (HELF) exposed to DOX with or without CMV infection.
• Assessment of cell viability and DNA fragmentation using TUNEL assay.
• Analysis of mitotic figures to detect cell cycle arrest.
• Quantitative PCR (qPCR) to analyze mRNA expression of p73 isoforms (TAp73 and dNp73).
• Caspase activation assays (caspases 8, 9, and 3).

Main Results:

• DOX treatment caused significant death (approx. 70%) in HELF cells within 24 hours.
• CMV infection markedly reduced DOX-induced cell death and DNA fragmentation (from 5.2% to 3.2%).
• DOX induced mitotic arrest, which was absent in CMV-infected cells.
• CMV infection led to increased TAp73 expression and the novel detection of dNp73 expression.
• TAp73 expression correlated with the lack of mitosis block, and while caspases were activated, cell death was less pronounced than with DOX alone.

Conclusions:

• CMV infection effectively attenuates doxorubicin-induced damage in normal human fibroblasts.
• The induction of TAp73 and dNp73 isoforms by CMV plays a crucial role in reducing DOX's cytotoxic effects.
• These findings suggest a potential therapeutic strategy for mitigating chemotherapy-induced toxicity by leveraging viral anti-apoptotic pathways.