Molecular alterations in metaphase chromosomes induced by bleomycin

• Published in: Spectrochimica acta. Part A, Molecular and biomolecular spectroscopy Vol. 312; p. 124026
• Main Authors: Urbańska, Marta, Sofińska, Kamila, Czaja, Michał, Szymoński, Krzysztof, Skirlińska-Nosek, Katarzyna, Seweryn, Sara, Lupa, Dawid, Szymoński, Marek, Lipiec, Ewelina
• Format: Journal Article
• Language: English
• Published: England Elsevier B.V 05.05.2024
• Subjects: Atomic force microscopy; Bleomycin; Bleomycin - pharmacology; Chromatin; Chromosomes; Convolutional neural networks; DNA; Humans; Metaphase; Raman spectroscopy; Atomic force microscopy; Bleomycin; Raman spectroscopy; Convolutional neural networks; Chromosomes
• ISSN: 1386-1425; 1873-3557
• DOI: 10.1016/j.saa.2024.124026

[Display omitted] •Drug-induced molecular changes were observed at the level of individual chromosome I.•Atomic force microscopy (AFM) and Raman microspectroscopy revealed structural and chemical alterations upon bleomycin.•The convolutional neural network (CNN) enabled extraction of chromosome I spectra from hyperspectral Raman maps.•The principal component analysis (PCA) algorithm revealed molecular markers of DNA damage.•Chromosomal aberrations, DNA methylation, conformational transitions, and intensified spectral signal of proteins were observed. Chromosomes are intranuclear structures, their main function is to store and transmit genetic information during cell division. They are composed of tightly packed DNA in the form of chromatin, which is constantly exposed to various damaging factors. The resulting changes in DNA can have serious consequences (e.g. mutations) if they are not repaired or repaired incorrectly. In this article, we studied chromosomes isolated from human cervical cancer cells (HeLa) exposed to a genotoxic drug causing both single- and double-strand breaks. Specifically, we used bleomycin to induce DNA damage. We followed morphological and chemical changes in chromosomes upon damage induction. Atomic force microscopy was used to visualize the morphology of chromosomes, while Raman microspectroscopy enabled the detection of changes in the chemical structure of chromatin with the resolution close to the diffraction limit. Additionally, we extracted spectra corresponding to chromosome I or chromatin from hyperspectral Raman maps with convolutional neural networks (CNN), which were further analysed with the principal component analysis (PCA) algorithm to reveal molecular markers of DNA damage in chromosomes. The applied multimodal approach revealed simultaneous morphological and molecular changes, including chromosomal aberrations, alterations in DNA conformation, methylation pattern, and increased protein expression upon the bleomycin treatment at the level of the single chromosome.