Molecular alterations in metaphase chromosomes induced by bleomycin

Area of Science:

• Genetics
• Molecular Biology
• Biophysics

Background:

• Chromosomes store and transmit genetic information but are susceptible to DNA damage from various factors.
• DNA damage, if unrepaired or misrepaired, can lead to mutations and serious cellular consequences.
• Understanding chromosome response to genotoxic agents is crucial for cancer research and therapy.

Purpose of the Study:

• To investigate morphological and chemical changes in human cervical cancer (HeLa) cell chromosomes induced by a genotoxic drug (bleomycin).
• To identify molecular markers of DNA damage at the single chromosome level.
• To apply a multimodal approach combining advanced microscopy and spectroscopy for detailed analysis.

Main Methods:

• Isolation of chromosomes from HeLa cells.
• Induction of DNA damage using the genotoxic drug bleomycin.
• Visualization of chromosome morphology using Atomic Force Microscopy (AFM).
• Detection of chemical structure changes using Raman Microspectroscopy.
• Analysis of hyperspectral Raman maps with Convolutional Neural Networks (CNN) and Principal Component Analysis (PCA).

Main Results:

• Bleomycin treatment induced both single- and double-strand breaks in HeLa cell chromosomes.
• Simultaneous morphological changes (chromosomal aberrations) and molecular alterations were observed.
• Detected changes include DNA conformation alterations, modified methylation patterns, and increased protein expression.

Conclusions:

• The multimodal approach successfully revealed comprehensive DNA damage responses at the single chromosome level.
• Identified molecular markers provide insights into the mechanisms of DNA damage and repair.
• Findings contribute to understanding the impact of genotoxic agents on chromosome structure and function.