Patched heterozygous mouse cerebellum

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1 WORKSHOP RADIAZIONI IONIZZANTI: NUOVI MODELLI PER LA STIMA DEL RISCHIO 1 ottobre 28, ENEA, Roma Oncogenic bystander radiation effects in Patched heterozygous mouse cerebellum Mariateresa Mancuso BAS-BIOTECMED ENEA CR-Casaccia

2 Mouse model PTCH PTCH protein Shh pathway SMO Ptc1 neo6-7/+ Ptc1 Gorlin Syndrome Hypersensitivity to ionizing radiation-induced tumorigenesis

IR-induced tumorigenesis in brain and skin Medulloblastoma Basal cell carcinoma Medulloblatoma incidence (%) 1 75 5 25 1 2 3 4 5 6 Latency (Weeks)

Greatly enhanced by irradiation in neonatal age 3. Early onset (2 weeks) 1. Develops only in irradiated mice (1-2% ) 2.

3 IR-induced tumorigenesis in brain and skin Medulloblastoma Basal cell carcinoma Medulloblatoma incidence (%) Latency (Weeks) P1 P2 P4 Gy BCC-like tumor incidence (%) 25 P P Latency (Weeks) 1. Relatively low spontaneous rate (about 7%) 2. Greatly enhanced by irradiation in neonatal age 3. Early onset (2 weeks) 1. Develops only in irradiated mice (1-2% ) 2. Can be induced by irradiation of newborn and adult mice 3. Late onset (45 weeks) Pazzaglia et al., Oncogene, 22, 26a, 26b Mancuso et al., Cancer Res, 24, 26 Pazzaglia et al., Cancer Res, 24

4 Irradiation set-up for neonatal mice WB 3 Gy (n = 37) CN (n = 51) Bar 1 (n = 4) Bar 2 (n = 45) Medulloblastoma incidence (%) Shield: lead bar (Ф 3mm) Weeks after irradiation 3 Gy In-vivo bystander effect?

5 Improved irradiation set-up for neonatal mice Shield: individual hoods (4mm-thick walls) 16 mm Φint = 1 mm 4 mm Dosimetry and Monte Carlo simulation 3 Gy x.12 =.36 Gy

6 High medulloblastoma incidence in shielded cerebellum of Ptch1 +/- mice Medulloblastoma incidence (%) P < Weeks after irradiation WB 3 Gy (37) SH 3 Gy (46) Gy (51) WB.36 Gy (34) P <.3 The incidence of medulloblastoma in shielded cerebellum is orders of magnitude higher than can be explained by the.36 Gy dose resulting from photon scattering

7 Biallelic Ptch1 loss (LOH) in tumors from WB or SH irradiated mice C416A A CT G T C C416A A T G T C 416 T Ptch1 Genetic damage is a critical component of in-vivo oncogenic bystander responses

that occupy the external granule layer (EGL) of

8 P2 The presumed cells-of-origin of medulloblastoma are undifferentiated precursors of granule neurons that occupy the external granule layer (EGL) of the developing cerebellum Ruiz i Altaba A. et al. 22

9 Induction of DSBs in irradiated and bystander EGL.5 h post-irradiation WB 3 Gy SH 3 Gy γ-h2ax staining declined in irradiated EGL at later times whilst remaining very low or undetectable in shielded EGL

10 Apoptosis in irradiated and bystander EGL WB SH 3h 6h 18h EGL ML Number of apoptotic cells (%) WB SH.36 Gy Time post-irradiation (h) A steep increase in apoptosis was detected at 6 h in the EGL of shielded mice relative to internal controls (WB.36 Gy)

11 Radiation bystander damage at higher dose SH 8.3 Gy WB.1 Gy DNA DSB No of cells with γ-h2ax foci (%) SH 8.3 Gy WB.1 Gy 3h 4.5h ** 6h * 18h APOPTOSIS No of apoptotic cells (%) h SH 8.3 Gy WB.1 Gy 4.5h *** 6h *** 18h Short-term cellular responses were not specific of radiosensitive Ptch1 +/- mice

12 No of cells with γ-h2ax foci (%) 4 3 Cx SH 8.3 Gy SH 8.3 Gy + TPA SH 8.3 Gy + Nms TPA ** Model of GJICs No of apoptotic cells (%) Nms *** COX-2 GJICs are crucial in mediating bystander responses in mouse CNS in vivo

13 Conclusions These results represent the first proof-of of-principle that bystander effects are factual in vivo events with carcinogenic potential Genetic damage, mediated by GJICs, is a critical component of in vivo oncogenic bystander responses Bystander effects are not specific of Ptch1-mutant mice and represent a cross-strain strain phenomenon

14 Work in progress 1. < 1 Gy Whole-body irradiation Medulloblatoma incidence (%) cGy 25cGy 1cGy Gy mm 3 Gy 22 mm Φint = 1 4

Acknowledgments Centro Ricerche Casaccia

Leonardi Mirella Tanori Simonetta Rebessi

Pia Toni Maria Pimpinella Vincenzo Covelli

Sezione di Tossicologia e Scienze Biomediche

15 Acknowledgments Centro Ricerche Casaccia Mariateresa Mancuso Emanuela Pasquali Simona Leonardi Mirella Tanori Simonetta Rebessi Vincenzo Di Majo Simonetta Pazzaglia Maria Pia Toni Maria Pimpinella Vincenzo Covelli Orsio Allegrucci Maurizio Quini Anna Saran Sezione di Tossicologia e Scienze Biomediche Istituto Nazionale di Metrologia delle Radiazioni Ionizzanti

16 cGy SH 25cGy 1cGy Gy Medulloblatoma incidence (%)

17 ** WB 3 Gy WB 3 Gy + TPA WB 3 Gy + Nms No of apoptotic cells (%)

18 Cx43 Model of GJICs TPA (2 ng/g b.w., 2-h intervals) Cx43 37 KDa SH 8.3 Gy SH 8.3 Gy + TPA cx43 β-actin

19 No of cells with γ-h2ax foci (%) SH 8.3 Gy SH 8.3 Gy + TPA SH 8.3 Gy + Nms (1.5 mg/kg b.w.) ** Nms No of apoptotic cells (%) COX *** GJICs are crucial in mediating bystander responses in mouse CNS in vivo

Modulation of Patched-Associated Susceptibility to Radiation Induced Tumorigenesis by Genetic Background

[CANCER RESEARCH 64, 3798 3806, June 1, 2004] Modulation of Patched-Associated Susceptibility to Radiation Induced Tumorigenesis by Genetic Background Simonetta Pazzaglia, 1 Mariateresa Mancuso, 1 Mirella