MODELLIZZAZIONE DI MORTE CELLULARE E DANNI CROMOSOMICI CON APPLICAZIONI PER L’ADROTERAPIA - PowerPoint Presentation

1. MODELLIZZAZIONE DI MORTE CELLULARE E DANNI CROMOSOMICI CON APPLICAZIONI PER L’ADROTERAPIAFrancesca Ballarini e Mario P. CaranteUniversità degli Studi di Pavia, Dipartimento di FisicaINFN – Sezione di Paviafrancesca.ballarini@unipv.itWorkshop CTL Life Sciences, 29 Febbraio 2016, CNAO, Pavia

2. Aberrazioni cromosomiche……e morte cellulare (clonogenica)George et al. 2001, Radiat Res 156 le aberrazioni cromosomiche possono portare sia a morte cellulare ( radioterapia) sia a conversione in cellula tumorale ( danno ai tessuti sani)dose-risposta lineare-quadratica, del tipo Y(D) = aD+bD2dose-risposta lineare-quadratica, del tipo S(D) = exp(-aD-bD2) la morte cellulare è l’obiettivo primario di qualunque terapia anti-tumorale

3. Rationale/BackgroundFurther information is needed on the action of charged particles in biological targets, e.g.: what are the features of the critical DNA damage type(s) leading to cell death and other important effects? what is the role of the spatial distribution of these damages in the cell nucleus (m scale)? How can this information be used to improve hadrontherapy, e.g. for predicting cell killing (and others effects) along Spread-Out Bragg Peaks? Basic research Applications

4. Utilità di modelli teorici (e codici di simulazione MC) per:comprendere meglio i meccanismi (scopo interpretativo)fare previsioni dove i dati sperimentali non sono disponibili (scopo predittivo)Esempio di utilizzo predittivo: i modelli di morte cellulare utilizzati nei piani di trattamento con ioni Carbonio (es.: il Local Effect Model di Scholz et al.)(Kagawa et al 2002 I J Rad Onc Biol Phys)

5. Energy depositions D N A ChromosomeNucleus CellDNA (cluster) damage (CL)(Lethal) Chromosome aberrations (d, f)Cell deathIl modello BIANCA (BIophysical ANalysis of Cell death and chromosome Aberrations)

6. Assumptions radiation  DNA (cluster) damage: radiation induces DNA “Cluster Lesions” (CLs), and each CL produces two independent chromosome fragments (<- repair of DSB clusters is likely to fail) the mean number of CLs/(Gy cell) is the 1st adjustable parameter, mainly dependent on radiation qualityDNA (cluster) damage  chromosome aberrations: two chromosome fragments can undergo rejoining (producing chromosome aberrations in case of rejoining with the incorrect partner) only if their initial distance is smaller than a threshold distance d (<- repair centres)d was fixed as the mean distance between two adjacent chromosomeschromosome aberrations  cell death: dicentrics, rings and large deletions (“Lethal Aberrations”) lead to cell death (<- observed experimentally for AG normal human fibroblasts exposed to X-rays)dicentricringdeletion

7. Simulation of cell nucleus…. ……………& irradiationspherical nucleus (cell suspensions)cylindrical nucleus (cell monolayers) front view each interphase chromosome territory is modelled by cubic voxels (side: 0.2 µm), with total volume proportional to the chromosome DNA content currently available genomes: human, hamster, rat X- and -rays: CLs uniformly distributed in the nucleusSp and α: CLs along segments representing the various particles number of particles: <n> = DS/(0.16LET) <CLs/particle> = (CLGy-1cell-1) x0.16 x LET / S hS’ > Sheavy ions like Carbon: CLs also outside the particle-track “core”

8. Examples of comparisons with chromosome aberration data the model/code can predict chromosome aberrations by different radiations in different cellshuman lymphocyteshuman fibroblasts(Ballarini and Ottolenghi 2003, Adv Space Res)alphas LET= 86 protons LET= 5 alphas LET= 116X-rays(Ballarini et al 2014, Radiat Environ Biophys)

9. Examples of comparison with cell survival data the relationship between lethal chromosome aberrations and cell death holds not only for AG1522 cells (normal, human), but also for V79 cells (radioresistant, hamster), and possibly others(Carante et al 2015, Radiat Environ Biophys) V79AGXXX- and -raysV79 cells (hamster fibroblasts):radioresistantAG1522 cells (human fibroblasts): normal

10. comparison with cell survival data II the approach works not only for photons but also for charged particlesAGV79(Carante et al 2015, Radiat Environ Biophys) 10.117.827.61.111.922.6protonsCarbon ionsV79AG(Carante et al 2015, Radiat Environ Biophys)C 13C 75C 49C 148

11. Comparisons with cell survival data III(Carante et al 2015, Radiat Environ Biophys)V79AG20285090120132alpha particles (-> C fragments, targeted therapy….)

12. applications for hadron therapy (1)(Chaudhary et al. 2014)project ETHICS, funded by INFN survival of AG normal cells irradiated in different positions of a proton SOBP at INFN-LNS in Catania, Italy (eye tumor therapy)(Carante and Ballarini, Frontiers in Oncology, in press)X-rays11.91.122.64.018.07.0

13. applications for hadron therapy (2) increase in biological effectiveness in the distal region for 1 mm beyond the SOBP, both effects are higher with respect to the entrance region  damage to normal tissue may be higher than expected applying a constant biological effectiveness (RBE=1.1)prediction of cell death and chromosome aberrations for AG normal cells @Catania dosecell deathlethal aberrations/celldoselethal aberrations/cellcell death

14. applications for hadron therapy (3) the increase of biological effectiveness in the distal region and the shift of the biological peak were confirmed the peak in biological effectiveness was sharper for V79 cells with respect to AG cellsprediction of cell death and chromosome aberrations for V79 radioresistant cells @Catania («virtual experiment»)lethal aberrations/cellfraction of inactivated cellsdose

15. On-going & future workmodelling activity of cell death and chromosome damage based on the BIANCA model/code, which is mechanism-based but uses only two adjustable parameters performing a more systematic comparison with exp. data by Carbon-ions (in coll. with CNAO - A. Facoetti et al.) extending the approach to other cell lines, including tumor cells refining the model, e.g. including other forms of cell death (e.g. apoptosis, in coll. with ENEA) and other lethal chromosome aberrations (e.g. complex exchanges), and modelling the cell-line radiosensitivity explicitly «coupling» the model with a radiation transport code and/or TPS (in coll. with CNAO – A. Mairani et al.) developing applications for targeted therapy with radionuclides

16. Characterization of DNA “Cluster Lesions” trend shown by CLs seems more similar to the trend of kbp-fragments with respect to bp-fragments  (also) kbp-fragments may be good candidates as critical DNA damage(Carante et al 2015, Radiat Environ Biophys)(fragment data: Tabocchini et al, Rydberg et al 2002, Alloni et al. 2010)(fragment data: Alloni et al. 2010, Friedland et al 2011)Comparison with DNA fragments with size at the base-pair scale (double-helix)Comparison with DNA fragments with size at the kilo-bp scale (nucleosomes)