title: Chk1 phosphorylated at serine345 is a predictor of early local recurrence and radio-resistance in breast cancer.
abstract: Radiation-induced DNA damage activates the DNA damage response (DDR). DDR up-regulation may predict radio-resistance and increase the risk of early local recurrence despite radiotherapy in early stage breast cancers. In 1755 early stage breast cancers, DDR signalling [ATM, ATR, total Ckh1, Chk1 phosphorylated at serine(345) (pChk1), Chk2, p53], base excision repair [PARP1, POLβ, XRCC1, FEN1, SMUG1], non-homologous end joining (Ku70/Ku80, DNA-PKcs) and homologous recombination [RAD51, BRCA1, γH2AX, BLM, WRN, RECQL5, PTEN] protein expression was correlated to time to early local recurrence. Pre-clinically, radio-sensitization by inhibition of Chk1 activation by ATR inhibitor (VE-821) and inhibition of Chk1 (V158411) were investigated in MDA-MB-231 (p53 mutant) and MCF-7 (p53 wild-type) breast cancer cells. In the whole cohort, 208/1755 patients (11.9%) developed local recurrence of which 126 (61%) developed local recurrence within 5 years of initiation of primary therapy. Of the 20 markers tested, only pChk1 and p53 significantly associated with early local recurrence (p value = 0.015 and 0.010, respectively). When analysed together, high cytoplasmic pChk1-nuclear pChk1 (p = 0.039), high cytoplasmic pChk1-p53 (p = 0.004) and high nuclear pChk1-p53 (p = 0.029) co-expression remain significantly linked to early local recurrence. In multivariate analysis, cytoplasmic pChk1 level independently predicted early local recurrence (p = 0.025). In patients who received adjuvant local radiotherapy (n = 949), p53 (p = 0.014) and high cytoplasmic pChk1-p53 (p = 0.017) remain associated with early local recurrence. Pre-clinically, radio-sensitisation by VE-821 or V158411 was observed in both MCF-7 and MDA-MB-231 cells and was more pronounced in MCF-7 cells. We conclude that pChk1 is a predictive biomarker of radiotherapy resistance and early local recurrence.
authors.affiliation: Academic Unit of Oncology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham NG51PB, UK.
authors.forename: Nouf
authors.initials: N
authors.lastname: Alsubhi
authors.affiliation: Northern Institute for Cancer Research, School of Clinical & Laboratory Sciences, Newcastle University, Medical School, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: Fiona
authors.initials: F
authors.lastname: Middleton
authors.affiliation: Department of Oncology, Nottingham University Hospitals, Nottingham NG51PB, UK.
authors.forename: Tarek M A
authors.initials: TM
authors.lastname: Abdel-Fatah
authors.affiliation: Northern Institute for Cancer Research, School of Clinical & Laboratory Sciences, Newcastle University, Medical School, Newcastle upon Tyne NE2 4HH, UK.
authors.forename: Peter
authors.initials: P
authors.lastname: Stephens
authors.affiliation: Academic Unit of Oncology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham NG51PB, UK.
authors.forename: Rachel
authors.initials: R
authors.lastname: Doherty
authors.affiliation: Academic Unit of Oncology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham NG51PB, UK.
authors.forename: Arvind
authors.initials: A
authors.lastname: Arora
authors.affiliation: Department of Oncology, Nottingham University Hospitals, Nottingham NG51PB, UK.
authors.forename: Paul M
authors.initials: PM
authors.lastname: Moseley
authors.affiliation: Department of Oncology, Nottingham University Hospitals, Nottingham NG51PB, UK.
authors.forename: Stephen Y T
authors.initials: SY
authors.lastname: Chan
authors.affiliation: Department of Pathology, School of Medicine, University of Nottingham, Nottingham NG51PB, UK.
authors.forename: Mohammed A
authors.initials: MA
authors.lastname: Aleskandarany
authors.affiliation: Department of Pathology, School of Medicine, University of Nottingham, Nottingham NG51PB, UK.
authors.forename: Andrew R
authors.initials: AR
authors.lastname: Green
authors.affiliation: Department of Pathology, School of Medicine, University of Nottingham, Nottingham NG51PB, UK.
authors.forename: Emad A
authors.initials: EA
authors.lastname: Rakha
authors.affiliation: Department of Pathology, School of Medicine, University of Nottingham, Nottingham NG51PB, UK.
authors.forename: Ian O
authors.initials: IO
authors.lastname: Ellis
authors.affiliation: Academic Unit of Oncology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham NG51PB, UK.
authors.forename: Stewart G
authors.initials: SG
authors.lastname: Martin
authors.affiliation: Northern Institute for Cancer Research, School of Clinical & Laboratory Sciences, Newcastle University, Medical School, Newcastle upon Tyne NE2 4HH, UK. Electronic address: nicola.curtin@ncl.ac.uk.
authors.forename: Nicola J
authors.initials: NJ
authors.lastname: Curtin
authors.affiliation: Academic Unit of Oncology, Division of Cancer and Stem Cells, School of Medicine, University of Nottingham, Nottingham NG51PB, UK; Department of Oncology, Nottingham University Hospitals, Nottingham NG51PB, UK. Electronic address: srinivasan.madhusudan@nottingham.ac.uk.
authors.forename: Srinivasan
authors.initials: S
authors.lastname: Madhusudan
mesh_terms: D064007:Ataxia Telangiectasia Mutated Proteins / Q000037:antagonists & inhibitors / Q000378:metabolism; D001943:Breast Neoplasms / Q000378:metabolism* / Q000532:radiotherapy / Q000628:therapy; D000071877:Checkpoint Kinase 1; D015331:Cohort Studies; D004260:DNA Repair; D004268:DNA-Binding Proteins / Q000378:metabolism*; D005260:Female; D055785:Gene Knockdown Techniques; D006801:Humans; D007211:Indoles / Q000494:pharmacology; D061986:MCF-7 Cells; D009364:Neoplasm Recurrence, Local / Q000378:metabolism* / Q000532:radiotherapy / Q000628:therapy; D009367:Neoplasm Staging; D010766:Phosphorylation; D011494:Protein Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D011719:Pyrazines / Q000494:pharmacology; D011728:Pyridones / Q000494:pharmacology; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D011836:Radiation Tolerance; D012694:Serine / Q000737:chemistry; D013450:Sulfones / Q000494:pharmacology; D015854:Up-Regulation
chemical_list: C560580:3-amino-6-(4-(methylsulfonyl)phenyl)-N-phenylpyrazine-2-carboxamide; D004268:DNA-Binding Proteins; D007211:Indoles; D011719:Pyrazines; D011728:Pyridones; D034741:RNA, Small Interfering; D013450:Sulfones; C000596547:V158411; D012694:Serine; D011494:Protein Kinases; C576597:ATR protein, human; D064007:Ataxia Telangiectasia Mutated Proteins; C000605867:CHEK1 protein, human; D000071877:Checkpoint Kinase 1
keywords: ATR inhibitor; Breast cancer; Chk1; Chk1 inhibitor; Local recurrence; Radiotherapy; Resistance; p53