Cancer Genome Instability. Coordinator: Capranico

G-quadruplex structure, R-loop and G-loop

Research Themes

The genome integrity maintenance is a complex process regulated by a plethora of proteins and nucleic acid structures. Since years of research, it is clear how non canonical DNA secondary structures are fundamental in regulating several processes such as gene expression, genome recombination and stability. In particular in our lab, we focused our study on R-loop and G-quadruplex (G4). R-loop are RNA: DNA hybrid formed by the nascent RNA during transcription which led the non-template strand in single strand status. Differently G-quadruplex are four-stranded structures formed by the stacking of four guanines arranged in a planar conformation named G-tetrad (see Figure 1). R-loops and G4s are physiologically structure of the mammalian genome, and they have a dynamic folding in the regulatory regions of the genome highlighting their function in driving DNA transcription and replication. Moreover, our lab elucidated the fundamental role of the crosstalk of these two structures in triggering genome instability. In particular we observed that the G-loop stabilization result to micronuclei formation.

Figure 2: Molecules able to target G-quadruplex structures (G4 binders) cause an R-loop-dependent genome instability which result to double strand break (DSBs) DNA damage. The DNA damage trigger micronuclei accumulation in the cytoplasm which are responsible for the cGAS/STING/IRF3 pathway activation. cGAS recruitment at micronuclei level causes STING activation which promotes IRF3 phosphorylation. The phosphorylated form of IRF3 translocate to the nucleus and result to the interferon B (IFNB) expression triggering an IFNB-dependent innate immune response in cancer cells.

Micronuclei are clear signature of genome instability, and they are responsible to activate an innate immune response in cancer cell through the cGAS activation. We published that both stabilization of G-quadruplex and R-loops structure result to an innate immune response mediated by cGAS-STING-IRF3 signalling pathway in different cancer cell lines. Moreover, a recent study elucidates the molecular mechanism of DNA damage promoted by TOP I poisons responsible for micronuclei formation.

In summary, our research goal is to establish molecular and epigenetic mechanisms dependent on non-B DNA structures of transcription regulation and genome instability. As several enzymes and other factors recognize these structures and regulate their stability and folding, mutations of these enzymes can affect diseases progression and therapeutic intervention. Thus, the discovery of regulation mechanisms involving R loops and G4s can reveal unexpected opportunities to develop strategies for personalized medicine in oncology, immunological disorders and neurodegenerative diseases.

Research activities are supported by funds from “Associazione Italiana per la Ricerca sul Cancro (AIRC), Ministero (PRIN), Unione Europea (PNRR), Fondazione del Monte e Fondazione CARISBO.

For additional information, visit our website.

Lab Members

Giovanni Capranico, Full Professor

Jessica Marinello, Associate Professor

Giulia Miglietta, Junior Assistance Professor

Marco Russo,  Research fellow (Post-doc)

Simona Pepe, Research fellow  (Post-doc)

Reneè C. Duardo, Research fellow (Post-doc)

Sara Morelli, PhD Student

Monica Procacci, PhD Student

Federico Guerra, PhD Student

Kostiantyn Romaniuk, Student

Gabriele Fanucchi, Student

Job Openings or Internship Projects

For students interested in knowing research topics of lab training for the preparation of master thesis and final dissertation, please contact directly Prof. Giovanni Capranico or Prof. Jessica Marinello

Main Publications

• Miglietta, G., Marinello, J., Russo, M., & Capranico, G. (2022). Ligands stimulating antitumour immunity as the next G-quadruplex challenge. Molecular Cancer, 21(1), 180. https://doi.org/10.1186/s12943-022-01649-y
• Marinello, J., Arleo, A., Russo, M., Delcuratolo, M., Ciccarelli, F., Pommier, Y., & Capranico, G. (2022). Topoisomerase I poison-triggered immune gene activation is markedly reduced in human small-cell lung cancers by impairment of the cGAS/STING pathway. British Journal of Cancer, 1–12. https://doi.org/10.1038/s41416-022-01894-4
• Miglietta, G. Russo, M., Duardo, R.C., Capranico, G., 2021. G-quadruplex binders as cytostatic modulators of innate immune genes in cancer cells. Nucleic Acids Research, 49, pp. 6673–86 https://doi.org/10.1093/nar/gkab500
• De Magis, A., Manzo, S.G., Russo, M., Marinello, J., Morigi, R., Sordet, O. and Capranico, G., 2019. DNA damage and genome instability by G-quadruplex ligands are mediated by R loops in human cancer cells. Proceedings of the National Academy of Sciences, 116(3), pp.816-825 https://doi.org/10.1073/pnas.1810409116
• Manzo, S.G., Hartono, S.R., Sanz, L.A., Marinello, J., De Biasi, S., Cossarizza, A., Capranico, G. and Chedin, F., 2018. DNA Topoisomerase I differentially modulates R-loops across the human genome. Genome biology, 19(1), pp.1-18 https://doi.org/10.1186/s13059-018-1478-1