Resistance to paclitaxel induces time-delayed multinucleation and DNA fragmentation into large fragments in MCF-7...

Area of Science:

• Cell Biology
• Molecular Oncology
• Pharmacology

Background:

• Paclitaxel is a crucial chemotherapy agent for breast cancer treatment.
• Understanding mechanisms of paclitaxel resistance is vital for improving patient outcomes.
• DNA damage and nuclear morphology changes are key indicators of drug-induced apoptosis.

Purpose of the Study:

• To investigate DNA fragmentation and nuclear abnormalities in paclitaxel-sensitive (MCF7) and paclitaxel-resistant (MCF7TAX19) breast cancer cells.
• To compare the cellular response to paclitaxel exposure between sensitive and resistant cell lines.

Main Methods:

• Exposure of MCF7 and MCF7TAX19 cells to paclitaxel for 24 hours.
• Analysis of DNA fragmentation using DNA agarose gel electrophoresis and flow cytometry (sub-G1 peak analysis).
• Assessment of nuclear abnormalities and multinucleated cell features via microscopy.

Main Results:

• No nucleosome-sized DNA fragmentation was detected by gel electrophoresis in either cell line.
• Flow cytometry revealed immediate DNA fragmentation (sub-G1 peak) in both cell lines upon paclitaxel exposure.
• Nuclear abnormalities (35-40% of cells) occurred immediately in MCF7 cells and were time-delayed in MCF7TAX19 cells.
• Resistant cells showed a significantly higher rate of multinucleated cell features after paclitaxel treatment, despite similar sub-G1 populations.

Conclusions:

• Paclitaxel induces DNA fragmentation and nuclear abnormalities in both sensitive and resistant breast cancer cells.
• Paclitaxel resistance is associated with a delayed onset of DNA fragmentation and an increased incidence of multinucleation.
• These findings highlight distinct cellular responses to paclitaxel in resistant cancer cells, offering insights into resistance mechanisms.