01 dn abreak

DNA Strand Breaks

and

Chromosomal

Aberrations

What is the practical

application? 2006/08/19 Sam

2006/08/19 Sam

Recurrent rectal cancer

Tx 63Gy/35 fractionsPain relief 9 months

Retreatment less effective?

Different patient response?

Inducible radioresistance?

Direct and indirect action of radiation

2006/08/19 SamPouget JP, Mather SJ. General aspects of the cellular response to low- and high-LET radiation. Eur J Nucl Med. 2001 Apr;28(4):541-61.

Representation of single-strand DNA molecule and sites of hydrolytic and oxidative attack.

2006/08/19 Sam

Pouget JP, Mather SJ. General aspects of the cellular response to low- and high-LET radiation. Eur J Nucl Med. 2001 Apr;28(4):541-61.

Different levels of chromatin organization are shown with a charged particle (arrow) entering from the left creating DNA damage (black dots) along its path.

2006/08/19 Sam

Desai N, Davis E, O'Neill P, Durante M, Cucinotta FA, Wu H. Immunofluorescence detection of clustered gamma-H2AX foci induced by HZE-particle radiation. Radiat Res. 2005 Oct;164(4 Pt 2):518-22.Rydberg B. Radiation-induced DNA damage and chromatin structure. Acta Oncol. 2001;40(6):682-5.

Structure of the nucleosome. (a) One DNA strand is shown in green and the other in brown. H2A is yellow; H2B, red; H3, blue; H4, green. (b) Space-filling model shown from the side. DNA is shown in white; histones are colored as in (a).

2006/08/19 Sam

Lodish, Harvey; Berk, Arnold; Zipursky, S. Lawrence; Matsudaira, Paul; Baltimore, David; Darnell, James E. Molecular Cell Biology. 4th ed. New York: W. H. Freeman & Co.; c2000.

• 8 histone proteins, 2 from each of 4 histone protein families, H4, H3, H2B, and H2A

• 3 H2A subfamiles - H2A1-H2A2, H2AZ, and H2AX

• in mammals the H2AZ represents about 10% of the H2A complement, the H2AX represents 2–25% (15%)

2006/08/19 Sam

2006/08/19 SamThe Cell - A Molecular Approach. 2nd ed. Cooper, Geoffrey M. Sunderland (MA): Sinauer Associates, Inc; c2000.

The 30 nm chromatin fiber as the target for DNA damage.

Multiple damaged sites

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Rydberg B. Radiation-induced DNA damage and chromatin structure. Acta Oncol. 2001;40(6):682-5.

Multiple damaged sites (MDS) are created that typically span less

than 20 bp of DNA -> DSB.

Schematic representations of the track structure of high and low-LET radiation.

2006/08/19 Sam

Desai N, Davis E, O'Neill P, Durante M, Cucinotta FA, Wu H. Immunofluorescence detection of clustered gamma-H2AX foci induced by HZE-particle radiation. Radiat Res. 2005 Oct;164(4 Pt 2):518-22. Fry DE, Schecter WP, Hartshorne MF. The surgeon and acts of civilian terrorism: radiation exposure and injury. J Am Coll Surg. 2006 Jan;202(1):146-54. Pouget JP, Mather SJ. General aspects of the cellular response to low- and high-LET radiation. Eur J Nucl Med. 2001 Apr;28(4):541-61.

Examples of

Radiation-induced

Aberrations

2006/08/19 Sam

(a) A situation with 2 DSBs on 2 chromosomes. End-joining reactions can occur among the 4 DSB free ends u, u', v and v'.

(b) A cell containing a translocation usually clonogenically viable, however which can result in transformation.

(c) A dicentric is usually clonogenically lethal.

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Sachs RK, Hlatky LR, Trask BJ. Radiation-produced chromosome aberrations: colourful clues. Trends Genet. 2000 Apr;16(4):143-6.

(d) 2 DSBs, but now on 1 chromosome instead of 2. (e) 1 possible outcome is a ring.

2006/08/19 Sam

Sachs RK, Hlatky LR, Trask BJ. Radiation-produced chromosome aberrations: colourful clues. Trends Genet. 2000 Apr;16(4):143-6.

(f) 3 DSBs, on 3 chromosomes; and (g) shows 1 possible outcome (out of 15).

(h) 3 DSBs, but now on only 2 chromosomes. 2 of the 15 possible outcomes are shown in (j) and (k).

2006/08/19 Sam

Sachs RK, Hlatky LR, Trask BJ. Radiation-produced chromosome aberrations: colourful clues. Trends Genet. 2000 Apr;16(4):143-6.

Lymphocyte metaphase

showing typical

chromatid damage

induced by X-irradiation in

G2.

b, break; g,

gap; sg, small gap.

2006/08/19 Sam

Baria K, Warren C, Eden OB, Roberts SA, West CM, Scott D. Chromosomal radiosensitivity in young cancer patients: possible evidence of genetic predisposition. Int J Radiat Biol. 2002 May;78(5):341-6.

Chromosome and chromatid aberrations produced by ionising radiation.

2006/08/19 SamPouget JP, Mather SJ. General aspects of the cellular response to low- and high-LET radiation. Eur J Nucl Med. 2001 Apr;28(4):541-61.

A normal human fibroblast cell at metaphase, after exposure to a 4 Gy dose of during the preceding interphase. A multiplex - FISH technique was used to ‘paint’ each of the homologous chromosome pairs a unique color. Arrow (a) shows where a segment of chromosome 7 is inserted into chromosome 12; (b) shows a ring derived from chromosome 1. A third pattern, involving 3 chromosomes and 3 breaks, includes (d), (e) and 1 other component. An additional pattern, involving 4 chromosomes and 7 breaks, includes (a)–(c) and some other components.

2006/08/19 Sam

Sachs RK, Hlatky LR, Trask BJ. Radiation-produced chromosome aberrations: colourful clues. Trends Genet. 2000 Apr;16(4):143-6.

2006/08/19 Sam

Chromosome analyses were carried out in peripheral lymphocytes of a 13-year-old boy exposed to protracted low dose-rate whole-body and short-time partial-body irradiation from a radiation accident in Estonia in 1994. Up to November 1998, the frequencies of translocations and dicentrics were periodically measured using FISH chromosome painting of the target chromosomes 1, 4 and 12, with a simultaneous pancentromeric probe.

Bauchinger M, Schmid E, Braselmann H. Time-course of translocation and dicentric frequencies in a radiation accident case. Int J Radiat Biol. 2001 May;77(5):553-7.

2006/08/19 Sam

RESULTS: For the yields of

dicentrics, an expected rapid temporal

decline was found with a half-time of

14.2+/-1.9 months. The yields of

reciprocal translocations also revealed

a gradual but significant reduction with

a half-time of 51.7+/-12.7 months.

Bauchinger M, Schmid E, Braselmann H. Time-course of translocation and dicentric frequencies in a radiation accident case. Int J Radiat Biol. 2001 May;77(5):553-7.

The 5 main DNA-repair pathways are:

• nucleotide excision repair (NER) (which involves global genome repair (GGR) and transcription-coupled repair (TCR)),•base excision repair (BER),•mismatch repair (MMR),•homologous recombination (HR) •non-homologous end joining (NHEJ) repair.

NER, BER and MMR lead to the excision of the damaged or mispaired bases, HR and NHEJ allow the repair of DSBs.

2006/08/19 Sam

Huang TT, D'Andrea AD. Regulation of DNA repair by ubiquitylation. Nat Rev Mol Cell Biol. 2006 May;7(5):323-34.

2006/08/19 SamHoeijmakers JH. Genome maintenance mechanisms for preventing cancer. Nature. 2001 May 17;411(6835):366-74.

2006/08/19 Sam

O'Driscoll M, Jeggo PA. The role of double-strand break repair - insights from human genetics. Nat Rev Genet. 2006 Jan;7(1):45-54.

2006/08/19 SamThe Cell - A Molecular Approach. 2nd ed. Cooper, Geoffrey M. Sunderland (MA): Sinauer Associates, Inc; c2000.

H2AX is activated

when DNA

molecules inside

the cell are broken

- such as radiation.

2006/08/19 Sam

2006/08/19 Sam

Downs JA, Jackson SP. Cancer: protective packaging for DNA. Nature. 2003 Aug 14;424(6950):732-4.

2006/08/19 Sam

Takahashi A, Ohnishi T. Does gammaH2AX foci formation depend on the presence of DNA double strand breaks? Cancer Lett. 2005 Nov 18;229(2):171-9.

2006/08/19 SamO'Driscoll M, Jeggo PA. The role of double-strand break repair - insights from human genetics. Nat Rev Genet. 2006 Jan;7(1):45-54.

2006/08/19 SamO'Driscoll M, Jeggo PA. The role of double-strand break repair - insights from human genetics. Nat Rev Genet. 2006 Jan;7(1):45-54.

2006/08/19 SamLobrich M, Kiefer J. Assessing the likelihood of severe side effects in radiotherapy. Int J Cancer. 2006 Jun 1;118(11):2652-6.

2006/08/19 Sam

These days people seek

knowledge, not wisdom.

Knowledge is of the past, wisdom is of the future.

VERNON COOPER

2006/08/19 Sam

“Predictive assays” :laboratory tests designedto predict the response of tumors and/or normal tissues to radiotherapy on the basis of their radiobiological characteristics.

Predictive assays

1.Reliable

2.Reproducible

3.Practical

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2006/08/19 Sam

There is significant

variability in outcome

with respect to both

tumor control

probability and normal

tissue damage.

2006/08/19 Sam

在基因表現方面，不同的實驗室有時會產生不同的結果。 RNA的實驗往往需要大件的檢體纔能得到高品質的 RNA，而 RNA的實驗也比 DNA實驗昂貴與費時。相對的 DNA比較穩定也比較容易做出來。使用 single nucleotide polymorphism (SNP)來做可以利用較容易取得的檢體如血液、口腔黏膜等組織。

2006/08/19 Sam

Ho AY, Atencio DP, Peters S, Stock RG, Formenti SC, Cesaretti JA, Green S, Haffty B, Drumea K, Leitzin L, Kuten A, Azria D, Ozsahin M, Overgaard J, Andreassen CN, Trop CS, Park J, Rosenstein BS. Genetic predictors of adverse radiotherapy effects: the Gene-PARE project. Int J Radiat Oncol Biol Phys. 2006 Jul 1;65(3):646-55.

ATM, TGFB1, XRCC1, XRCC3, SOD2, hHR21, 5557 G->A variant in ATM,Thr/Thr genotype in XRCC3 codon 241

2006/08/19 Sam

Chinnaiyan P, Allen GW, Harari PM. Radiation and new molecular agents, part II: targeting HDAC, HSP90, IGF-1R, PI3K, and Ras. Semin Radiat Oncol. 2006 Jan;16(1):59-64.

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Choudhury A, Cuddihy A, Bristow RG. Radiation and new molecular agents part I: targeting ATM-ATR checkpoints, DNA repair, and the proteasome. Semin Radiat Oncol. 2006 Jan;16(1):51-8.

2006/08/19 Sam

Choudhury A, Cuddihy A, Bristow RG. Radiation and new molecular agents part I: targeting ATM-ATR checkpoints, DNA repair, and the proteasome. Semin Radiat Oncol. 2006 Jan;16(1):51-8.

2006/08/19 Sam

Choudhury A, Cuddihy A, Bristow RG. Radiation and new molecular agents part I: targeting ATM-ATR checkpoints, DNA repair, and the proteasome. Semin Radiat Oncol. 2006 Jan;16(1):51-8.