Widespread activation of the DNA damage response in human pancreatic intraepithelial neoplasia

Examining Sporadic Cancer Mutations Uncovers a Set of Genes Involved in Mitochondrial Maintenance

Mitochondria are key organelles for cellular health and metabolism and the activation of programmed cell death processes. Although pathways for regulating and re-establishing mitochondrial homeostasis have been identified over the past twenty years, the consequences of disrupting genes that regulate other cellular processes, such as division and proliferation, on affecting mitochondrial function remain unclear. In this study, we leveraged insights about increased sensitivity to mitochondrial damage in certain cancers, or genes that are frequently mutated in multiple cancer types, to compile a list of candidates for study. RNAi was used to disrupt orthologous genes in the model organism Caenorhabditis elegans, and a series of assays were used to evaluate these genes' importance for mitochondrial health. Iterative screening of ~1000 genes yielded a set of 139 genes predicted to play roles in mitochondrial maintenance or function. Bioinformatic analyses indicated that these genes are statistically interrelated. Functional validation of a sample of genes from this set indicated that disruption of each gene caused at least one phenotype consistent with mitochondrial dysfunction, including increased fragmentation of the mitochondrial network, abnormal steady-state levels of NADH or ROS, or altered oxygen consumption. Interestingly, RNAi-mediated knockdown of these genes often also exacerbated α-synuclein aggregation in a C. elegans model of Parkinson's disease. Additionally, human orthologs of the gene set showed enrichment for roles in human disorders. This gene set provides a foundation for identifying new mechanisms that support mitochondrial and cellular homeostasis.

The biology of pancreatic cancer morphology

Pancreatic ductal adenocarcinoma (PDAC) is one of the most lethal of all human malignancies. PDAC precursor lesions, invasive primary PDAC, and metastatic PDAC each display distinct morphologies that reflect unique biology. This 'biomorphology' is determined by a complex neoplastic history of clonal phylogenetic relationships, geographic locations, external environmental exposures, intrinsic metabolic demands, and tissue migration patterns. Understanding the biomorphological evolution of PDAC progression is not only of academic interest but also of great practical value. Applying this knowledge to surgical pathology practice facilitates the correct diagnosis on routine H&E stains without additional ancillary studies in most cases. Here I provide a concise overview of the entire biomorphological spectrum of PDAC progression beginning with initial neoplastic transformation and ending in terminal distant metastasis. Most biopsy and resection specimens are currently obtained prior to treatment. As such, our understanding of untreated PDAC biomorphology is mature. The biomorphology of treated PDAC is less defined but will assume greater importance as the frequency of neoadjuvant therapy increases. Although this overview is slanted towards pathology, it is written so that pathologists, clinicians, and scientists alike might find it instructive for their respective disciplines.

Early Detection in a Mouse Model of Pancreatic Cancer by Imaging DNA Damage Response Signaling

Despite its widespread use in oncology, the PET radiotracer 18F-FDG is ineffective for improving early detection of pancreatic ductal adenocarcinoma (PDAC). An alternative strategy for early detection of pancreatic cancer involves visualization of high-grade pancreatic intraepithelial neoplasias (PanIN-3s), generally regarded as the noninvasive precursors of PDAC. The DNA damage response is known to be hyperactivated in late-stage PanINs. Therefore, we investigated whether the SPECT imaging agent 111In-anti-γH2AX-TAT allows visualization of the DNA damage repair marker γH2AX in PanIN-3s in an engineered mouse model of PDAC, to facilitate early detection of PDAC. Methods: Genetically engineered KPC (KRasLSL.G12D/+; p53LSL.R172H/+; PdxCre) mice were imaged with 18F-FDG and 111In-anti-γH2AX-TAT. The presence of PanIN/PDAC as visualized by histologic examination was compared with autoradiography and immunofluorescence. Separately, the survival of KPC mice imaged with 111In-anti-γH2AX-TAT was evaluated. Results: In KPC mouse pancreata, γH2AX expression was increased in high-grade PanINs but not in PDAC, corroborating earlier results obtained from human pancreas sections. Uptake of 111In-anti-γH2AX-TAT, but not 111In-IgG-TAT or 18F-FDG, within the pancreas correlated positively with the age of KPC mice, which correlated with the number of high-grade PanINs. 111In-anti-γH2AX-TAT localizes preferentially in high-grade PanIN lesions but not in established PDAC. Younger, non-tumor-bearing KPC mice that show uptake of 111In-anti-γH2AX-TAT in the pancreas survive for a significantly shorter time than mice with physiologic 111In-anti-γH2AX-TAT uptake. Conclusion:111In-anti-γH2AX-TAT imaging allows noninvasive detection of DNA damage repair signaling upregulation in preinvasive PanIN lesions and is a promising new tool to aid in the early detection and staging of pancreatic cancer.

Age-related morphological changes in the pancreas and their association with pancreatic carcinogenesis

Age-related pathological changes in the pancreas have been unclear because they are often minor and nonspecific. However, recent studies have shown that they are closely related to various pathological conditions such as pancreatic cancer and diabetes mellitus. Knowledge of age-related changes is important to determine appropriate prevention, detection, and treatment strategies for various diseases observed in elderly patients. We present a review of the pathological age-related non-neoplastic changes in the exocrine pancreas such as pancreatic fatty replacement, lobulocentric pancreatic atrophy, pancreatic duct ectasia, and metaplasia of exocrine pancreas, as well as changes in islet cells. We have discussed common pancreatic neoplasms in elderly patients, such as pancreatic intraepithelial neoplasia (PanIN), intraductal papillary mucinous neoplasms (IPMNs), and pancreatic ductal adenocarcinoma (PDAC). Age-related pathological changes play a key role in pancreatic carcinogenesis via telomere dysfunction. Further studies are warranted to clarify molecular mechanisms of pancreatic carcinogenesis in elderly patients.

Germline Variants and Risk for Pancreatic Cancer: A Systematic Review and Emerging Concepts

Pancreatic cancer requires many genetic mutations. Combinations of underlying germline variants and environmental factors may increase the risk of cancer and accelerate the oncogenic process. We systematically reviewed, annotated, and classified previously reported pancreatic cancer-associated germline variants in established risk genes. Variants were scored using multiple criteria and binned by evidence for pathogenicity, then annotated with published functional studies and associated biological systems/pathways. Twenty-two previously identified pancreatic cancer risk genes and 337 germline variants were identified from 97 informative studies that met our inclusion criteria. Fifteen of these genes contained 66 variants predicted to be pathogenic (APC, ATM, BRCA1, BRCA2, CDKN2A, CFTR, CHEK2, MLH1, MSH2, NBN, PALB2, PALLD, PRSS1, SPINK1, TP53). Pancreatic cancer risk genes were organized into key biological mechanisms that promote pancreatic oncogenesis within an oncogenic model. Development of precision medicine approaches requires updated variant information within the framework of an oncogenic progression model. Complex risk modeling may improve interpretation of early biomarkers and guide pathway-specific treatment for pancreatic cancer in the future. Precision medicine is within reach.

A genetic roadmap of pancreatic cancer: still evolving

A diagnosis of pancreatic ductal adenocarcinoma (PDA) is often fatal. PDA is widely recognised as one of the 'incurable cancers' because therapies against this tumour type are generally ineffective. The fatal nature of this tumour is due to its aggressive clinical course. Pancreatic cancer commonly presents at the metastatic stage; even in cases where tumours are localised to the pancreas at diagnosis, metastatic seeds have often been invariably been spawned off, frustrating surgical attempts to cure the cancer. The key principles of pancreatic cancer mutational development were outlined nearly two decades ago using the genetics of precursor lesions to position the various stages of tumour progression. Since then, there has been a cavalcade of new data. How these recent studies impact the classical perceptions of pancreatic cancer development is a work in progress. Given that significant improvements in patient outcomes are not in sight for this disease, it is likely that broadening the current perspectives and acquiring deeper biological insights into the morphogenetic route of tumour development will be needed to foster new strategies for more effective cancer control.

ATM-deficiency increases genomic instability and metastatic potential in a mouse model of pancreatic cancer

Germline mutations in ATM (encoding the DNA-damage signaling kinase, ataxia-telangiectasia-mutated) increase Familial Pancreatic Cancer (FPC) susceptibility, and ATM somatic mutations have been identified in resected human pancreatic tumors. Here we investigated how Atm contributes to pancreatic cancer by deleting this gene in a murine model of the disease expressing oncogenic Kras (KrasG12D). We show that partial or total ATM deficiency cooperates with KrasG12D to promote highly metastatic pancreatic cancer. We also reveal that ATM is activated in pancreatic precancerous lesions in the context of DNA damage and cell proliferation, and demonstrate that ATM deficiency leads to persistent DNA damage in both precancerous lesions and primary tumors. Using low passage cultures from primary tumors and liver metastases we show that ATM loss accelerates Kras-induced carcinogenesis without conferring a specific phenotype to pancreatic tumors or changing the status of the tumor suppressors p53, p16Ink4a and p19Arf. However, ATM deficiency markedly increases the proportion of chromosomal alterations in pancreatic primary tumors and liver metastases. More importantly, ATM deficiency also renders murine pancreatic tumors highly sensitive to radiation. These and other findings in our study conclusively establish that ATM activity poses a major barrier to oncogenic transformation in the pancreas via maintaining genomic stability.

Imaging the DNA damage response with PET and SPECT

DNA integrity is constantly challenged by endogenous and exogenous factors that can alter the DNA sequence, leading to mutagenesis, aberrant transcriptional activity, and cytotoxicity. Left unrepaired, damaged DNA can ultimately lead to the development of cancer. To overcome this threat, a series of complex mechanisms collectively known as the DNA damage response (DDR) are able to detect the various types of DNA damage that can occur and stimulate the appropriate repair process. Each DNA damage repair pathway leads to the recruitment, upregulation, or activation of specific proteins within the nucleus, which, in some cases, can represent attractive targets for molecular imaging. Given the well-established involvement of DDR during tumorigenesis and cancer therapy, the ability to monitor these repair processes non-invasively using nuclear imaging techniques may facilitate the earlier detection of cancer and may also assist in monitoring response to DNA damaging treatment. This review article aims to provide an overview of recent efforts to develop PET and SPECT radiotracers for imaging of DNA damage repair proteins.

Perspectives on the combination of radiotherapy and targeted therapy with DNA repair inhibitors in the treatment of pancreatic cancer

Pancreatic cancer is highly lethal. Current research that combines radiation with targeted therapy may dramatically improve prognosis. Cancerous cells are characterized by unstable genomes and activation of DNA repair pathways, which are indicated by increased phosphorylation of numerous factors, including H2AX, ATM, ATR, Chk1, Chk2, DNA-PKcs, Rad51, and Ku70/Ku80 heterodimers. Radiotherapy causes DNA damage. Cancer cells can be made more sensitive to the effects of radiation (radiosensitization) through inhibition of DNA repair pathways. The synergistic effects, of two or more combined non-lethal treatments, led to co-administration of chemotherapy and radiosensitization in BRCA-defective cells and patients, with promising results. ATM/Chk2 and ATR/Chk1 pathways are principal regulators of cell cycle arrest, following DNA double-strand or single-strand breaks. DNA double-stranded breaks activate DNA-dependent protein kinase, catalytic subunit (DNA-PKcs). It forms a holoenzyme with Ku70/Ku80 heterodimers, called DNA-PK, which catalyzes the joining of nonhomologous ends. This is the primary repair pathway utilized in human cells after exposure to ionizing radiation. Radiosensitization, induced by inhibitors of ATM, ATR, Chk1, Chk2, Wee1, PP2A, or DNA-PK, has been demonstrated in preclinical pancreatic cancer studies. Clinical trials are underway. Development of agents that inhibit DNA repair pathways to be clinically used in combination with radiotherapy is warranted for the treatment of pancreatic cancer.

Breast primary epithelial cells that escape p16-dependent stasis enter a telomere-driven crisis state

Breast cancer is the most common malignant disease in women, but some basic questions remain in breast cancer biology. To answer these, several cell models were developed. Recently, the use of improved cell-culture conditions has enabled the development of a new primary cell model with certain luminal characteristics. This model is relevant because, after the introduction of a specific set of genetic elements, the transformed cells yielded tumors resembling human adenocarcinomas in mice. The use of improved cell-culture conditions supporting the growth of these breast primary epithelial cells was expected to delay or eliminate stress-induced senescence and lead to the propagation of normal cells. However, no studies have been carried out to investigate these points. Propagation of breast primary epithelial cells was performed in WIT medium on Primaria plates. Immunofluorescence, western blot and qRT-PCR were used to detect molecular markers, and to determine the integrity of DNA damage-response pathways. Promoter methylation of p16 (INK4a) was assessed by pyrosequencing. In order to obtain a dynamic picture of chromosome instability over time in culture, we applied FISH methodologies. To better link chromosome instability with excessive telomere attrition, we introduced the telomerase reverse transcriptase human gene using a lentiviral vector. We report here that breast primary epithelial cells propagated in vitro with WIT medium on Primaria plates express some luminal characteristics, but not a complete luminal lineage phenotype. They undergo a p16-dependent stress-induced senescence (stasis), and the cells that escape stasis finally enter a crisis state with rampant chromosome instability. Chromosome instability in these cells is driven by excessive telomere attrition, as distributions of chromosomes involved in aberrations correlate with the profiles of telomere signal-free ends. Importantly, ectopic expression of the human TERT gene rescued their chromosomal instability phenotype. Essentially, our data show that contrary to what was previously suggested, improved culture conditions to propagate in vitro mammary epithelial cells with some luminal characteristics do not prevent stress-induced senescence. This barrier is overcome by spontaneous methylation of the p16 (INK4a) promoter, allowing the proliferation of cells with telomere dysfunction and ensuing chromosome instability.

Ataxia-telangiectasia-mutated protein kinase levels stratify patients with pancreatic adenocarcinoma into prognostic subgroups with loss being a strong indicator of poor survival

OBJECTIVES

Recently, aberrations in the gene encoding for ataxia-telangiectasia-mutated (ATM) protein kinase have been reported for pancreatic ductal adenocarcinomas (PDAC). These findings argue that ATM deficiency may play a role during carcinogenesis. Therefore, in this study, we investigated the clinical relevance of ATM expression and ATM activation in PDAC.

METHODS

Both ATM expression and nuclear phosphoSer1981-ATM levels were assessed by immunohistochemistry in a cohort of 133 PDAC and correlated with clinicopathological parameters.

RESULTS

We found stratification in prognostic subgroups. Complete loss of Ser1981-ATM was indicative of the worst prognosis (median survival, 10.8 vs 14.3 months [low expression] vs 31.1 months [high expression], P < 0.001). Similarly, analysis of ATM expression demonstrated absent expression levels of ATM to be associated with dismal prognosis (median survival, 9.6 months), whereas expression of ATM in general was associated with increased survival (17.7 months, P = 0.001).

CONCLUSIONS

Our analysis shows that both ATM expression and activated ATM are prognostic markers in PDAC with respect to standard clinicopathological parameters. These results suggest that ATM should be further explored as prognostic as well as predictive factor with respect to conventional chemotherapies and for putative synthetic lethal approaches.

Gradual telomere shortening and increasing chromosomal instability among PanIN grades and normal ductal epithelia with and without cancer in the pancreas

A large body of evidence supports a key role for telomere dysfunction in carcinogenesis due to the induction of chromosomal instability. To study telomere shortening in precancerous pancreatic lesions, we measured telomere lengths using quantitative fluorescence in situ hybridization in the normal pancreatic duct epithelium, pancreatic intraepithelial neoplasias (PanINs), and cancers. The materials employed included surgically resected pancreatic specimens without cancer (n = 33) and with invasive ductal carcinoma (n = 36), as well as control autopsy cases (n = 150). In comparison with normal ducts, telomere length was decreased in PanIN-1, −2 and −3 and cancer. Furthermore, telomeres were shorter in cancer than in PanIN-1 and −2. Telomere length in cancer was not associated with histological type, lesion location, or cancer stage. PanINs with or without cancer showed similar telomere lengths. The incidences of atypical mitosis and anaphase bridges, which are morphological characteristics of chromosomal instability, were negatively correlated with telomere length. The telomeres in normal duct epithelium became shorter with aging, and those in PanINs or cancers were shorter than in age-matched controls, suggesting that telomere shortening occurs even when histological changes are absent. Our data strongly suggest that telomere shortening occurs in the early stages of pancreatic carcinogenesis and progresses with precancerous development. Telomere shortening and chromosomal instability in the duct epithelium might be associated with carcinogenesis of the pancreas. Determination of telomere length in pancreatic ductal lesions may be valuable for accurate detection and risk assessment of pancreatic cancer.

Imaging DNA damage allows detection of preneoplasia in the BALB-neuT model of breast cancer

A prominent feature of many human cancers is oncogene-driven activation of the DNA damage response (DDR) during early tumorigenesis. It has been shown previously that noninvasive imaging of the phosphorylated histone H2A variant H2AX, γH2AX, a DNA damage signaling protein, is possible using (111)In-labeled anti-γH2AX antibody conjugated to the cell-penetrating peptide transactivator of transcription (TAT). The purpose of this study was to investigate whether (111)In-anti-γH2AX-TAT detects the DDR during mammary oncogenesis in BALB-neuT mice.

METHODS

Mammary fat pads from BALB-neuT and wild-type mice (age, 40-106 d) were immunostained for γH2AX. (111)In-anti-γH2AX-TAT or a control probe was administered intravenously to BALB-neuT mice. SPECT was performed weekly and compared with tumor detection using palpation and dynamic contrast-enhanced MR imaging.

RESULTS

γH2AX expression was elevated in hyperplastic lesions in the mammary fat pads of BALB-neuT mice aged 76-106 d, compared with normal fat pads from younger mice and carcinomas from older mice (13.5 ± 1.2 γH2AX foci/cell vs. 5.2 ± 1.5 [P < 0.05] and 3.4 ± 1.1 [P < 0.001], respectively). Serial SPECT imaging revealed a 2.5-fold increase in (111)In-anti-γH2AX-TAT accumulation in the mammary fat pads of mice aged 76-106 d, compared with control probe (P = 0.01). The median time to detection of neoplastic lesions by (111)In-anti-γH2AX-TAT (defined as >5% injected dose per gram of tissue) was 96 d, compared with 120 and 131 d for dynamic contrast-enhanced MR imaging and palpation, respectively (P < 0.001).

CONCLUSION

DDR imaging using (111)In-anti-γH2AX-TAT identified mammary tumors significantly earlier than MR imaging. Imaging the DDR holds promise for the detection of preneoplasia and as a technique for screening cancer-prone individuals.

Detection of DNA damage in peripheral blood mononuclear cells from pancreatic cancer patients

DNA repair is a key mechanism in maintaining genomic stability: repair deficiencies increase DNA damage and mutations that lead to several diseases, including cancer. We extracted DNA from peripheral blood mononuclear cells (PBMCs) of 48 pancreatic adenocarcinoma cases and 48 healthy controls to determine relative levels of nuclear DNA (nDNA) and mitochondrial DNA (mtDNA) damage by QPCR. All participants were never smokers and between the ages of 60 and 69. Average levels among cases were compared to controls using a rank sum test, and logistic regression adjusted for potential confounding factors (age, sex, and diabetes mellitus). Cases had less DNA damage, with a significant decrease in mtDNA damage (P-value = 0.03) and a borderline significant decrease in nDNA damage (P = 0.08). Across samples, we found mtDNA abundance was higher among non-diabetics compared to diabetics (P = 0.04). Our results suggest that patients with pancreatic adenocarcinoma have less DNA damage in their PBMCs, and that having diabetes, a known pancreatic cancer risk factor, is associated with lower levels of mtDNA abundance.

Functional p38 MAPK identified by biomarker profiling of pancreatic cancer restrains growth through JNK inhibition and correlates with improved survival

PURPOSE

Numerous biomarkers for pancreatic cancer have been reported. We determined the extent to which such biomarkers are expressed throughout metastatic progression, including those that effectively predict biologic behavior.

EXPERIMENTAL DESIGN

Biomarker profiling was performed for 35 oncoproteins in matched primary and metastatic pancreatic cancer tissues from 36 rapid autopsy patients. Proteins of significance were validated by immunolabeling in an independent sample set, and functional studies were performed in vitro and in vivo.

RESULTS

Most biomarkers were similarly expressed or lost in expression in most samples analyzed, and the matched primary and metastases from a specific patient were most similar to each other than to other patients. However, a subset of proteins showed extensive interpatient heterogeneity, one of which was p38 MAPK. Strong positive pp38 MAPK immunolabeling was significantly correlated with improved postresection survival by multivariate analysis (median overall survival 27.9 months, P = 0.041). In pancreatic cancer cells, inhibition of functional p38 by SB202190 increased cell proliferation in vitro in both low-serum and low-oxygen conditions. High functional p38 activity in vitro corresponded to lower levels of pJNK protein expression, and p38 inhibition resulted in increased pJNK and pMKK7 by Western blot analysis. Moreover, JNK inhibition by SP600125 or MKK7 siRNA knockdown antagonized the effects of p38 inhibition by SB202190. In vivo, SP600125 significantly decreased growth rates of xenografts with high p38 activity compared with those without p38 expression.

CONCLUSIONS

Functional p38 MAPK activity contributes to overall survival through JNK signaling, thus providing a rationale for JNK inhibition in pancreatic cancer management.

Contribution of environment and genetics to pancreatic cancer susceptibility

Several risk factors have been identified as potential contributors to pancreatic cancer development, including environmental and lifestyle factors, such as smoking, drinking and diet, and medical conditions such as diabetes and pancreatitis, all of which generate oxidative stress and DNA damage. Oxidative stress status can be modified by environmental factors and also by an individual's unique genetic makeup. Here we examined the contribution of environment and genetics to an individual's level of oxidative stress, DNA damage and susceptibility to pancreatic cancer in a pilot study using three groups of subjects: a newly diagnosed pancreatic cancer group, a healthy genetically-unrelated control group living with the case subject, and a healthy genetically-related control group which does not reside with the subject. Oxidative stress and DNA damage was evaluated by measuring total antioxidant capacity, direct and oxidative DNA damage by Comet assay, and malondialdehyde levels. Direct DNA damage was significantly elevated in pancreatic cancer patients (age and sex adjusted mean ± standard error: 1.00 ± 0.05) versus both healthy unrelated and related controls (0.70 ± 0.06, p<0.001 and 0.82 ± 0.07, p = 0.046, respectively). Analysis of 22 selected SNPs in oxidative stress and DNA damage genes revealed that CYP2A6 L160H was associated with pancreatic cancer. In addition, DNA damage was found to be associated with TNFA -308G>A and ERCC4 R415Q polymorphisms. These results suggest that measurement of DNA damage, as well as select SNPs, may provide an important screening tool to identify individuals at risk for development of pancreatic cancer.

Telomerase inhibitor Imetelstat (GRN163L) limits the lifespan of human pancreatic cancer cells

Telomerase is required for the unlimited lifespan of cancer cells. The vast majority of pancreatic adenocarcinomas overexpress telomerase activity and blocking telomerase could limit their lifespan. GRN163L (Imetelstat) is a lipid-conjugated N3'→P5' thio-phosphoramidate oligonucleotide that blocks the template region of telomerase. The aim of this study was to define the effects of long-term GRN163L exposure on the maintenance of telomeres and lifespan of pancreatic cancer cells. Telomere size, telomerase activity, and telomerase inhibition response to GRN163L were measured in a panel of 10 pancreatic cancer cell lines. The cell lines exhibited large differences in levels of telomerase activity (46-fold variation), but most lines had very short telomeres (2-3 kb in size). GRN163L inhibited telomerase in all 10 pancreatic cancer cell lines, with IC50 ranging from 50 nM to 200 nM. Continuous GRN163L exposure of CAPAN1 (IC50 = 75 nM) and CD18 cells (IC50 = 204 nM) resulted in an initial rapid shortening of the telomeres followed by the maintenance of extremely short but stable telomeres. Continuous exposure to the drug eventually led to crisis and to a complete loss of viability after 47 (CAPAN1) and 69 (CD18) doublings. Crisis In these cells was accompanied by activation of a DNA damage response (γ-H2AX) and evidence of both senescence (SA-β-galactosidase activity) and apoptosis (sub-G1 DNA content, PARP cleavage). Removal of the drug after long-term GRN163L exposure led to a reactivation of telomerase and re-elongation of telomeres in the third week of cultivation without GRN163L. These findings show that the lifespan of pancreatic cancer cells can be limited by continuous telomerase inhibition. These results should facilitate the design of future clinical trials of GRN163L in patients with pancreatic cancer.

Influence of MRE11, RAD50 and NIBRIN protein expression on survival in pancreatic carcinoma after curative resection

The MRE11/RAD50/NIBRIN complex, a protein complex that repairs DNA double-strand breaks, could serve as an early marker for new lesions in pancreatic cancer. We determined the expression of MRE11, RAD50 and NIBRIN, and their possible prognostic value regarding survival. Forty-one patients with ductal adenocarcinoma of the pancreas were included. All underwent curative surgery. Immunohistochemistry was performed for MRE11, RAD50 and NIBRIN. Subsequent analyses were based on a modified immunoreactive score. Statistical analysis was conducted using the statistics program "R". The mean follow-up period was 509 days. The mean age of the patients was 67±8 years, male=56%, female=44%. Eighty-seven percent underwent a Kausch-Whipple procedure, whereas a left side resection was performed in 22% of patients. Positive lymph nodes were found in 80% of cases, and patients were staged UICC IIa (12%), IIb (56%) and IV (29%). Overall significant results were found for MRE11 (p=0.02) and NIBRIN (p=0.01) expression and postoperative survival. We found a significant relation between the expression of MRE11, NIBRIN and the postoperative survival of patients with ductal adenocarcinoma. The link between the expression of the MRN complex, ATM and pancreatic cancer can be used to develop new treatment options for pancreatic carcinoma.

S100A4 expression is a prognostic indicator in small intestine adenocarcinoma

AIMS

Due to the rarity of small intestine adenocarcinoma (SIAC), estimating the prognosis for patients with surgically resected SIAC is difficult. Overexpression of S100A4 has been linked to worse patient survival in several malignant neoplasms, but its significance in SIAC has not been determined.

METHODS

S100A4 protein expression was assessed in 197 surgically resected SIAC cases and compared with clinicopathological factors, including patient survival.

RESULTS

A progressive increase in S100A4 labelling was observed in normal intestinal epithelium, adenoma and adenocarcinoma (p<0.001), and 50 SIAC cases (26.2%) showed strong S100A4 expression. Patients with SIAC with strong S100A4 expression had a higher pT classification (p=0.05), as well as increased lymph node metastasis (p=0.009) and perineural invasion (p=0.002). Patients with SIAC with strong S100A4 expression had significantly worse survival (median survival, 21 months) than those with weak/no S100A4 expression (42.5 months) by univariable (p=0.04) and multivariable (p=0.01) analyses.

CONCLUSIONS

S100A4 overexpression is observed in a subset of SIACs, is associated with advanced disease and can be used as a prognostic indicator of poor prognosis in patients with SIAC.

Increased expression of phosphorylated NBS1, a key molecule of the DNA damage response machinery, is an adverse prognostic factor in patients with de novo myelodysplastic syndromes

The expression of activated forms of key proteins of the DNA damage response machinery (pNBS1, pATM and γH2AX) was assessed by means of immunohistochemistry in bone marrow biopsies of 74 patients with de novo myelodysplastic syndromes (MDS) and compared with 15 cases of de novo acute myeloid leukemia (AML) and 20 with reactive bone marrow histology. Expression levels were significantly increased in both MDS and AML, compared to controls, being higher in high-risk than in low-risk MDS. Increased pNBS1 and γH2AX expression possessed a significant negative prognostic impact for overall survival in MDS patients, whereas pNBS1 was an independent marker of poor prognosis.

Combined loss of E-cadherin and aberrant β-catenin protein expression correlates with a poor prognosis for small intestinal adenocarcinomas

Small intestinal adenocarcinomas (SIACs) are rare, and their molecular pathogenesis is largely unknown. To define the roles of E-cadherin and β-catenin, we performed immunohistochemistry for E-cadherin and β-catenin in 194 surgically resected SIACs with tissue microarrays and compared the data with clinicopathologic factors, including survival rates of patients with SIAC. Loss of E-cadherin expression and aberrant β-catenin expression were observed in 41.8% (81/194 cases) and 40.7% (79/194 cases) of SIACs, respectively. Combined loss of E-cadherin and aberrant β-catenin expression was observed in 24.2% (47/194 cases) of SIACs, and this feature was most frequently observed in mucinous adenocarcinomas and signet ring cell carcinomas (P < .001), poorly differentiated and undifferentiated carcinomas (P < .001), and tumors with advanced pT classification (P = .03). Survival times for patients with SIAC with both loss of E-cadherin and aberrant β-catenin expression (median, 13.9 months) were significantly shorter than those for patients without aberrant expression of both proteins (49.9 months), as determined by univariate (P < .001) and multivariate (P = .01) analyses. In conclusion, loss of E-cadherin and aberrant β-catenin expression correlate with poorly differentiated tumors, advanced T classification, and decreased patient survival time; therefore, it could be a prognostic factor in patients with SIAC.

Cancer cell growth and survival as a system-level property sustained by enhanced glycolysis and mitochondrial metabolic remodeling

Systems Biology holds that complex cellular functions are generated as system-level properties endowed with robustness, each involving large networks of molecular determinants, generally identified by “omics” analyses. In this paper we describe four basic cancer cell properties that can easily be investigated in vitro: enhanced proliferation, evasion from apoptosis, genomic instability, and inability to undergo oncogene-induced senescence. Focusing our analysis on a K-ras dependent transformation system, we show that enhanced proliferation and evasion from apoptosis are closely linked, and present findings that indicate how a large metabolic remodeling sustains the enhanced growth ability. Network analysis of transcriptional profiling gives the first indication on this remodeling, further supported by biochemical investigations and metabolic flux analysis (MFA). Enhanced glycolysis, down-regulation of TCA cycle, decoupling of glucose and glutamine utilization, with increased reductive carboxylation of glutamine, so to yield a sustained production of growth building blocks and glutathione, are the hallmarks of enhanced proliferation. Low glucose availability specifically induces cell death in K-ras transformed cells, while PKA activation reverts this effect, possibly through at least two mitochondrial targets. The central role of mitochondria in determining the two investigated cancer cell properties is finally discussed. Taken together the findings reported herein indicate that a system-level property is sustained by a cascade of interconnected biochemical pathways that behave differently in normal and in transformed cells.

Frequent ATRX, CIC, FUBP1 and IDH1 mutations refine the classification of malignant gliomas

Mutations in the critical chromatin modifier ATRX and mutations in CIC and FUBP1, which are potent regulators of cell growth, have been discovered in specific subtypes of gliomas, the most common type of primary malignant brain tumors. However, the frequency of these mutations in many subtypes of gliomas, and their association with clinical features of the patients, is poorly understood. Here we analyzed these loci in 363 brain tumors. ATRX is frequently mutated in grade II-III astrocytomas (71%), oligoastrocytomas (68%), and secondary glioblastomas (57%), and ATRX mutations are associated with IDH1 mutations and with an alternative lengthening of telomeres phenotype. CIC and FUBP1 mutations occurred frequently in oligodendrogliomas (46% and 24%, respectively) but rarely in astrocytomas or oligoastrocytomas ( more than 10%). This analysis allowed us to define two highly recurrent genetic signatures in gliomas: IDH1/ATRX (I-A) and IDH1/CIC/FUBP1 (I-CF). Patients with I-CF gliomas had a significantly longer median overall survival (96 months) than patients with I-A gliomas (51 months) and patients with gliomas that did not harbor either signature (13 months). The genetic signatures distinguished clinically distinct groups of oligoastrocytoma patients, which usually present a diagnostic challenge, and were associated with differences in clinical outcome even among individual tumor types. In addition to providing new clues about the genetic alterations underlying gliomas, the results have immediate clinical implications, providing a tripartite genetic signature that can serve as a useful adjunct to conventional glioma classification that may aid in prognosis, treatment selection, and therapeutic trial design.

Obesity, autophagy and the pathogenesis of liver and pancreatic cancers

Liver and pancreatic cancers are both highly lethal diseases with limited to no therapeutic options for patients. Recent studies suggest that deregulated autophagy plays a role in the pathogenesis of these diseases by perturbing cellular homeostasis and laying the foundation for disease development. While accumulation of p62 upon impaired autophagy has been implicated in hepatocellular carcinoma, its role in pancreatic ductal adenocarcinoma remains less clear. This review will focus on recent studies illustrating the role of autophagy in liver and pancreatic cancers. The relationships between autophagy, nuclear factor-κB signaling and obesity in hepatocellular carcinoma will be discussed, as well as the dual role of autophagy in pancreatic ductal adenocarcinoma.

Genome-wide CpG island profiling of intraductal papillary mucinous neoplasms of the pancreas

PURPOSE

Intraductal papillary mucinous neoplasms (IPMN) are precursors to infiltrating pancreatic ductal adenocarcinomas. Widespread epigenetic alterations are characteristic of many cancers, yet few studies have systematically analyzed epigenetic alterations of neoplastic precursors. Our goal was to conduct genome-wide CpG island methylation profiling to identify aberrantly methylated loci in IPMNs.

EXPERIMENTAL DESIGN

We compared the CpG island methylation profiles of six IPMNs to normal primary pancreatic duct samples using methylation CpG island amplification (MCA) and Agilent CpG island microarray (MCAM) analysis. When selected 13 genes identified as differentially methylated by MCAM for methylation-specific PCR (MSP) analysis in an independent set of IPMNs and normal pancreas samples and conducted expression analysis of selected genes.

RESULTS

We identified 2,259 loci as differentially methylated in at least one of six IPMNs including 245 genes hypermethylated in IPMNs with high-grade dysplasia compared with normal pancreatic duct samples. Eleven of 13 genes evaluated by MSP were more commonly methylated in 61 IPMNs than in 43 normal pancreas samples. Several genes (BNIP3, PTCHD2, SOX17, NXPH1, EBF3) were significantly more likely to be methylated in IPMNs with high-grade than with low-grade dysplasia. One gene, SOX17, showed loss of protein expression by immunohistochemistry in 22% (19 of 88) of IPMNs. The most specific marker, BNIP3, was not methylated in any IPMNs with low-grade dysplasia or in normal pancreas samples.

CONCLUSIONS

IPMNs undergo extensive aberrant CpG island hypermethylation. The detection of genes selectively methylated in high-grade IPMNs such as BNIP3 may have use in the clinical evaluation of IPMNs.

DNA Damage Response is Prominent in Ovarian High-Grade Serous Carcinomas, Especially Those with Rsf-1 (HBXAP) Overexpression

DNA damage commonly occurs in cancer cells as a result of endogenous and tumor microenvironmental stress. In this study, we applied immunohistochemistry to study the expression of phosphorylated Chk2 (pChk2), a surrogate marker of the DNA damage response, in high grade and low grade of ovarian serous carcinoma. A phospho-specific antibody specific for threonine 68 of Chk2 was used for immunohistochemistry on a total of 292 ovarian carcinoma tissues including 250 high-grade and 42 low-grade serous carcinomas. Immunostaining intensity was correlated with clinicopathological features. We found that there was a significant correlation between pChk2 immunostaining intensity and percentage of pChk2 positive cells in tumors and demonstrated that high-grade serous carcinomas expressed an elevated level of pChk2 as compared to low-grade serous carcinomas. Normal ovarian, fallopian tube, ovarian cyst, and serous borderline tumors did not show detectable pChk2 immunoreactivity. There was no significant difference in pChk2 immunoreactivity between primary and recurrent high-grade serous carcinomas. In high-grade serous carcinomas, a significant correlation (P < 0.0001) in expression level (both in intensity and percentage) was found between pChk2 and Rsf-1 (HBXAP), a gene involved in chromatin remodeling that is amplified in high-grade serous carcinoma. Our results suggest that the DNA damage response is common in high-grade ovarian serous carcinomas, especially those with Rsf-1 overexpression, suggesting that Rsf-1 may be associated with DNA damage response in high-grade serous carcinomas.

RAS oncogenes: weaving a tumorigenic web

RAS proteins are essential components of signalling pathways that emanate from cell surface receptors. Oncogenic activation of these proteins owing to missense mutations is frequently detected in several types of cancer. A wealth of biochemical and genetic studies indicates that RAS proteins control a complex molecular circuitry that consists of a wide array of interconnecting pathways. In this Review, we describe how RAS oncogenes exploit their extensive signalling reach to affect multiple cellular processes that drive tumorigenesis.

Expression of DNA damage response biomarkers during oral carcinogenesis

Emerging evidence suggests that an intact DNA damage response (DDR) serves as a potent barrier to malignant transformation. Using immunohistochemistry and patient-derived biopsy samples, we investigated whether the same may hold true during oral carcinogenesis. DNA damage accumulates early in the development of oral squamous cell carcinoma (OSCC) as evidenced by the detection of surrogate DDR biomarkers γ-H2A.X and phosphorylated CHK2-threonine-68 (phospho-CHK2(Thr68)) in epithelial hyperplasias. However, whereas γ-H2A.X expression peaked in dysplastic epithelium, its levels were significantly reduced in OSCCs (χ(2) = 7.655; P = .02). In contrast, there was a trend toward increased phospho-CHK2(Thr68) expression with increasing severity of the pathology. Nonetheless, combined expression of the biomarkers was significantly greater in the nontransformed tissues relative to OSCCs (χ(2) = 6.42; P = .04). Thus, our findings suggest that early therapeutic exploitation of the DDR may be worthy of investigation as a means by which to limit OSCC development.

Molecular characteristics of pancreatic ductal adenocarcinoma

Pancreatic cancer is an almost universally lethal disease and despite extensive research over the last decades, this has not changed significantly. Nevertheless, much progress has been made in understanding the pathogenesis of pancreatic ductal adenocarcinoma (PDAC) suggesting that different therapeutic strategies based on these new insights are forthcoming. Increasing focus exists on designing the so-called targeted treatment strategies in which the genetic characteristics of a tumor guide therapy. In the past, the focus of research was on identifying the most frequently affected genes in PDAC, but with the complete sequencing of the pancreatic cancer genome the focus has shifted to defining the biological function that the altered genes play. In this paper we aimed to put the genetic alterations present in pancreatic cancer in the context of their role in signaling pathways. In addition, this paper provides an update of the recent advances made in the development of the targeted treatment approach in PDAC.