TY - JOUR
T1 - Widespread activation of the DNA damage response in human pancreatic intraepithelial neoplasia
AU - Koorstra, Jan Bart M.
AU - Hong, Seung Mo
AU - Shi, Chanjuan
AU - Meeker, Alan K.
AU - Ryu, Ji Kon
AU - Offerhaus, George Johan A.
AU - Goggins, Michael G.
AU - Hruban, Ralph H.
AU - Maitra, Anirban
N1 - Funding Information:
Supported by the Sol Goldman Pancreatic Cancer Research Center, the Michael Rolfe Foundation for Pancreatic Cancer Research and the NIH SPORE in GI Cancers P50CA062924. J-BMK is supported by the Netherlands Cancer Research Foundation (KWF) and International Exchange Program Grant provided by the University Medical Center Utrecht. The authors are grateful to Professor David A. Tuveson (Cambridge Research Institute, UK) for his insightful discussions on this paper.
PY - 2009/11
Y1 - 2009/11
N2 - Pancreatic intraepithelial neoplasia (PanIN) lesions are the most common non-invasive precursors of pancreatic adenocarcinoma. We postulated that accumulating DNA damage within the PanIN epithelium activates checkpoint mechanisms. Tissue microarrays were constructed from 81 surgically resected primary pancreatic adenocarcinomas and an independent set of 58 PanIN lesions (31 PanIN-1, 14 PanIN-2, and 13 PanIN-3). Immunohistochemical labeling was carried out using anti-γH2AX Ser139, anti-phosphoATM Ser1981, anti-phosphoChk2 Thr68, and anti-p53. A histologic score combining area and intensity of labeling in the nuclear compartment was determined for each lesion. A progressive increase in γH2AX Ser139 labeling, consistent with escalating DNA damage, was observed in the non-invasive precursor lesions (scores of 4.34, 6.21, and 7.50, respectively, for PanIN-1,-2, and-3), compared with the pancreatic ductal epithelium (score 2.36) (ANOVA, P0.0001). In conjunction, activation of the ataxia telangiectasia mutated (ATM)-Chk2 checkpoint pathway was observed in all histological grades of PanIN lesions. Specifically, pATM Ser1981 histologic scores for PanIN-1, PanIN-2, and PanIN-3 were 4.83, 5.14, and 7.17, respectively, versus 2.33 for the ductal epithelium (ANOVA, P0.0001); the corresponding scores for pChk2 Thr68 were 5.43, 7.64, and 5.44 in PanINs-1,-2, and-3, respectively, versus 2.75 in the ductal epithelium (ANOVA, P0.0001). In contrast, absent to minimal nuclear p53 was observed in the ductal epithelium, and in PanINs-1 and-2 (a histologic score of 0-1.86), with a significant upregulation (corresponding to mutational inactivation) seen only at the stage of PanIN-3 and invasive neoplasia (histologic scores of 4.00 and 4.22). Nuclear p53 accumulation in cancers was associated with attenuation of the ATM-Chk2 checkpoint and a restitution to baseline levels. To conclude, activation of the ATM-Chk2 checkpoint pathway is commonly observed in PanINs, likely in response to the accumulating DNA damage from events such as oncogene mutations and telomere dysfunction. Loss of p53 function appears to be a critical determinant for bypassing this checkpoint and the subsequent progression to invasive adenocarcinoma.
AB - Pancreatic intraepithelial neoplasia (PanIN) lesions are the most common non-invasive precursors of pancreatic adenocarcinoma. We postulated that accumulating DNA damage within the PanIN epithelium activates checkpoint mechanisms. Tissue microarrays were constructed from 81 surgically resected primary pancreatic adenocarcinomas and an independent set of 58 PanIN lesions (31 PanIN-1, 14 PanIN-2, and 13 PanIN-3). Immunohistochemical labeling was carried out using anti-γH2AX Ser139, anti-phosphoATM Ser1981, anti-phosphoChk2 Thr68, and anti-p53. A histologic score combining area and intensity of labeling in the nuclear compartment was determined for each lesion. A progressive increase in γH2AX Ser139 labeling, consistent with escalating DNA damage, was observed in the non-invasive precursor lesions (scores of 4.34, 6.21, and 7.50, respectively, for PanIN-1,-2, and-3), compared with the pancreatic ductal epithelium (score 2.36) (ANOVA, P0.0001). In conjunction, activation of the ataxia telangiectasia mutated (ATM)-Chk2 checkpoint pathway was observed in all histological grades of PanIN lesions. Specifically, pATM Ser1981 histologic scores for PanIN-1, PanIN-2, and PanIN-3 were 4.83, 5.14, and 7.17, respectively, versus 2.33 for the ductal epithelium (ANOVA, P0.0001); the corresponding scores for pChk2 Thr68 were 5.43, 7.64, and 5.44 in PanINs-1,-2, and-3, respectively, versus 2.75 in the ductal epithelium (ANOVA, P0.0001). In contrast, absent to minimal nuclear p53 was observed in the ductal epithelium, and in PanINs-1 and-2 (a histologic score of 0-1.86), with a significant upregulation (corresponding to mutational inactivation) seen only at the stage of PanIN-3 and invasive neoplasia (histologic scores of 4.00 and 4.22). Nuclear p53 accumulation in cancers was associated with attenuation of the ATM-Chk2 checkpoint and a restitution to baseline levels. To conclude, activation of the ATM-Chk2 checkpoint pathway is commonly observed in PanINs, likely in response to the accumulating DNA damage from events such as oncogene mutations and telomere dysfunction. Loss of p53 function appears to be a critical determinant for bypassing this checkpoint and the subsequent progression to invasive adenocarcinoma.
KW - ATM
KW - Chk2
KW - DNA damage
KW - Pancreatic cancer
KW - Pancreatic intraepithelial neoplasia
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U2 - 10.1038/modpathol.2009.114
DO - 10.1038/modpathol.2009.114
M3 - Article
C2 - 19668150
AN - SCOPUS:70350694254
VL - 22
SP - 1439
EP - 1445
JO - Modern Pathology
JF - Modern Pathology
SN - 0893-3952
IS - 11
ER -