CHEK2

Gene Summary

Gene:CHEK2; checkpoint kinase 2
Aliases: CDS1, CHK2, LFS2, RAD53, hCds1, HuCds1, PP1425
Location:22q12.1
Summary:In response to DNA damage and replication blocks, cell cycle progression is halted through the control of critical cell cycle regulators. The protein encoded by this gene is a cell cycle checkpoint regulator and putative tumor suppressor. It contains a forkhead-associated protein interaction domain essential for activation in response to DNA damage and is rapidly phosphorylated in response to replication blocks and DNA damage. When activated, the encoded protein is known to inhibit CDC25C phosphatase, preventing entry into mitosis, and has been shown to stabilize the tumor suppressor protein p53, leading to cell cycle arrest in G1. In addition, this protein interacts with and phosphorylates BRCA1, allowing BRCA1 to restore survival after DNA damage. Mutations in this gene have been linked with Li-Fraumeni syndrome, a highly penetrant familial cancer phenotype usually associated with inherited mutations in TP53. Also, mutations in this gene are thought to confer a predisposition to sarcomas, breast cancer, and brain tumors. This nuclear protein is a member of the CDS1 subfamily of serine/threonine protein kinases. Several transcript variants encoding different isoforms have been found for this gene. [provided by RefSeq, Apr 2012]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:serine/threonine-protein kinase Chk2
Source:NCBIAccessed: 13 March, 2017

Ontology:

What does this gene/protein do?
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Pathways:What pathways are this gene/protein implicaed in?
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Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 13 March 2017 using data from PubMed using criteria.

Literature Analysis

Mouse over the terms for more detail; many indicate links which you can click for dedicated pages about the topic.

Tag cloud generated 13 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (6)

Data table showing topics related to specific cancers and associated disorders. Scope includes mutations and abnormal protein expression.

Note: list is not exhaustive. Number of papers are based on searches of PubMed (click on topic title for arbitrary criteria used).

Latest Publications: CHEK2 (cancer-related)

Yao J, Huang A, Zheng X, et al.
53BP1 loss induces chemoresistance of colorectal cancer cells to 5-fluorouracil by inhibiting the ATM-CHK2-P53 pathway.
J Cancer Res Clin Oncol. 2017; 143(3):419-431 [PubMed] Related Publications
PURPOSE: Loss of P53 binding protein 1 (53BP1) is considered a poor prognostic factor for colorectal cancer. However, its effect on chemosensitivity of colorectal cancer to 5-fluorouracil (5-FU) remains elusive. This study aimed to examine the association of 53BP1 expression with chemosensitivity of colorectal cancer cells to 5-FU.
METHODS: Immunohistochemistry was performed on 30 metastatic colorectal cancer samples to assess the associations of 53BP1 levels with clinical therapeutic effects. In vitro, IC50 values for 5-FU and 53BP1 levels were determined by MTT assay and Western blot in 5 colorectal cancer cell lines. Then, 53BP1 was silenced in HCT116 and HT29 cells, and cell proliferation, apoptosis and cell cycle distribution were evaluated. Relative protein levels of ATM-CHK2-P53 pathway effectors and Bcl-2 family members were measured by Western blot. Finally, the effects of 53BP1 knockdown on tumor growth and 5-FU chemoresistance were investigated in vivo.
RESULTS: 53BP1 expression was closely related to time to progression (TTP) after first-line chemotherapy. Namely, 53BP1 downregulation resulted in reduced TTP. In addition, 53BP1 silencing increased proliferation, inhibited apoptosis and induced S phase arrest in HCT116 and HT29 cells after 5-FU treatment. Moreover, 53BP1 knockdown also reduced the protein levels of ATM-CHK2-P53 apoptotic pathway effectors, caspase9 and caspase3, while increasing Bcl-2 expression. In vivo, 53BP1 silencing accelerated tumor proliferation in nude mice and enhanced resistance to 5-FU.
CONCLUSIONS: These findings confirmed that 53BP1 loss might be a negative factor for chemotherapy efficacy, promoting cell proliferation and inhibiting apoptosis by suppressing ATM-CHK2-P53 signaling, and finally inducing 5-FU resistance.

Yokoi M, Hanaoka F
Two mammalian homologs of yeast Rad23, HR23A and HR23B, as multifunctional proteins.
Gene. 2017; 597:1-9 [PubMed] Related Publications
Mammalian cells express two homologs of yeast Rad23, the so-called homolog of Rad23 (HR23) proteins. The HR23 proteins were identified more than two decades ago as factors involved in initiation of global genome nucleotide excision repair (GG-NER) along with their interacting partner, xeroderma pigmentosum group C (XPC) protein. Because the HR23 genes encode proteins harboring ubiquitin-like (UBL) domains at their N-termini and two ubiquitin-associated (UBA) domains in their central- and C-terminal regions, the link between HR23 proteins and proteolytic degradation has been widely explored by several methods, including yeast two-hybrid screening and co-affinity purification. To date, various HR23 protein partners have been identified, and these proteins are involved not only in DNA repair, but also in ubiquitin-dependent protein degradation, transcriptional regulation, and cell cycle control. In addition, establishment of mouse strains lacking the HR23 genes and RNA silencing of these genes in human cells demonstrated their significance in animal development and cell growth. Through these studies, the functional differences between the two HR23 proteins have been gradually revealed. Furthermore, recent comprehensive proteomic analyses will help to elucidate the functional protein-protein networks involving the HR23 proteins.

Baloch AH, Khosa AN, Bangulzai N, et al.
Novel Nonsense Variants c.58C>T (p.Q20X) and c.256G>T (p.E85X) in the CHEK2 Gene Identified in Breast Cancer Patients from Balochistan.
Asian Pac J Cancer Prev. 2016; 17(7):3623-6 [PubMed] Related Publications
Breast cancer is very common and the leading cause of cancer deaths among women globally. Hereditary cases account for 510% of the total burden and CHEK2, which plays crucial role in response to DNA damage to promote cell cycle arrest and repair or induce apoptosis, is considered as a moderate penetrance breast cancer risk gene. Our objective in the current study was to analyze mutations in related to breast cancer. A total of 271 individuals including breast cancer patients and normal subjects were enrolled and all 14 exons of CHEK2 were amplified and sequenced. The majority of the patients (>95%) were affected with invasive ductal carcinoma (IDC), 52.1% were diagnosed with grade III tumors and 56.2% and 27.5% with advanced stages III and IV. Two novel nonsense variants i.e. c.58C>T (P.Q20X) and c.256G>T (p.E85X) at exon 1 and 2 in two breast cancer patients were identified, both novel and not reported elsewhere.

Zhuang X, Li Y, Cao H, et al.
Case report of a Li-Fraumeni syndrome-like phenotype with a de novo mutation in CHEK2.
Medicine (Baltimore). 2016; 95(29):e4251 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Cases of multiple tumors are rarely reported in China. In our study, a 57-year-old female patient had concurrent squamous cell carcinoma, mucoepidermoid carcinoma, brain cancer, bone cancer, and thyroid cancer, which has rarely been reported to date.
METHODS: To determine the relationship among these multiple cancers, available DNA samples from the thyroid, lung, and skin tumors and from normal thyroid tissue were sequenced using whole exome sequencing.
RESULTS: The notable discrepancies of somatic mutations among the 3 tumor tissues indicated that they arose independently, rather than metastasizing from 1 tumor. A novel deleterious germline mutation (chr22:29091846, G->A, p.H371Y) was identified in CHEK2, a Li-Fraumeni syndrome causal gene. Examining the status of this novel mutation in the patient's healthy siblings revealed its de novo origin.
CONCLUSION: Our study reports the first case of Li-Fraumeni syndrome-like in Chinese patients and demonstrates the important contribution of de novo mutations in this type of rare disease.

Pritchard CC, Mateo J, Walsh MF, et al.
Inherited DNA-Repair Gene Mutations in Men with Metastatic Prostate Cancer.
N Engl J Med. 2016; 375(5):443-53 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Inherited mutations in DNA-repair genes such as BRCA2 are associated with increased risks of lethal prostate cancer. Although the prevalence of germline mutations in DNA-repair genes among men with localized prostate cancer who are unselected for family predisposition is insufficient to warrant routine testing, the frequency of such mutations in patients with metastatic prostate cancer has not been established.
METHODS: We recruited 692 men with documented metastatic prostate cancer who were unselected for family history of cancer or age at diagnosis. We isolated germline DNA and used multiplex sequencing assays to assess mutations in 20 DNA-repair genes associated with autosomal dominant cancer-predisposition syndromes.
RESULTS: A total of 84 germline DNA-repair gene mutations that were presumed to be deleterious were identified in 82 men (11.8%); mutations were found in 16 genes, including BRCA2 (37 men [5.3%]), ATM (11 [1.6%]), CHEK2 (10 [1.9% of 534 men with data]), BRCA1 (6 [0.9%]), RAD51D (3 [0.4%]), and PALB2 (3 [0.4%]). Mutation frequencies did not differ according to whether a family history of prostate cancer was present or according to age at diagnosis. Overall, the frequency of germline mutations in DNA-repair genes among men with metastatic prostate cancer significantly exceeded the prevalence of 4.6% among 499 men with localized prostate cancer (P<0.001), including men with high-risk disease, and the prevalence of 2.7% in the Exome Aggregation Consortium, which includes 53,105 persons without a known cancer diagnosis (P<0.001).
CONCLUSIONS: In our multicenter study, the incidence of germline mutations in genes mediating DNA-repair processes among men with metastatic prostate cancer was 11.8%, which was significantly higher than the incidence among men with localized prostate cancer. The frequencies of germline mutations in DNA-repair genes among men with metastatic disease did not differ significantly according to age at diagnosis or family history of prostate cancer. (Funded by Stand Up To Cancer and others.).

Kristeleit RS, Miller RE, Kohn EC
Gynecologic Cancers: Emerging Novel Strategies for Targeting DNA Repair Deficiency.
Am Soc Clin Oncol Educ Book. 2016; 35:e259-68 [PubMed] Related Publications
The presence of a BRCA mutation, somatic or germline, is now established as a standard of care for selecting patients with ovarian cancer for treatment with a PARP inhibitor. During the clinical development of the PARP inhibitor class of agents, a subset of women without BRCA mutations were shown to respond to these drugs (termed "BRCAness"). It was hypothesized that other genetic abnormalities causing a homologous recombinant deficiency (HRD) were sensitizing the BRCA wild-type cancers to PARP inhibition. The molecular basis for these other causes of HRD are being defined. They include individual gene defects (e.g., RAD51 mutation, CHEK2 mutation), homozygous somatic loss, and whole genome properties such as genomic scarring. Testing this knowledge is possible when selecting patients to receive molecular therapy targeting DNA repair, not only for patients with ovarian cancer but also endometrial and cervical cancers. The validity of HRD assays and multiple gene sequencing panels to select a broader population of patients for treatment with PARP inhibitor therapy is under evaluation. Other non-HRD targets for exploiting DNA repair defects in gynecologic cancers include mismatch repair (MMR), checkpoint signaling, and nonhomologous end-joining (NHEJ) DNA repair. This article describes recent evidence supporting strategies in addition to BRCA mutation for selecting patients for treatment with PARP inhibitor therapy. Additionally, the challenges and opportunities of exploiting DNA repair pathways other than homologous recombination for molecular therapy in gynecologic cancers is discussed.

Mucaki EJ, Caminsky NG, Perri AM, et al.
A unified analytic framework for prioritization of non-coding variants of uncertain significance in heritable breast and ovarian cancer.
BMC Med Genomics. 2016; 9:19 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Sequencing of both healthy and disease singletons yields many novel and low frequency variants of uncertain significance (VUS). Complete gene and genome sequencing by next generation sequencing (NGS) significantly increases the number of VUS detected. While prior studies have emphasized protein coding variants, non-coding sequence variants have also been proven to significantly contribute to high penetrance disorders, such as hereditary breast and ovarian cancer (HBOC). We present a strategy for analyzing different functional classes of non-coding variants based on information theory (IT) and prioritizing patients with large intragenic deletions.
METHODS: We captured and enriched for coding and non-coding variants in genes known to harbor mutations that increase HBOC risk. Custom oligonucleotide baits spanning the complete coding, non-coding, and intergenic regions 10 kb up- and downstream of ATM, BRCA1, BRCA2, CDH1, CHEK2, PALB2, and TP53 were synthesized for solution hybridization enrichment. Unique and divergent repetitive sequences were sequenced in 102 high-risk, anonymized patients without identified mutations in BRCA1/2. Aside from protein coding and copy number changes, IT-based sequence analysis was used to identify and prioritize pathogenic non-coding variants that occurred within sequence elements predicted to be recognized by proteins or protein complexes involved in mRNA splicing, transcription, and untranslated region (UTR) binding and structure. This approach was supplemented by in silico and laboratory analysis of UTR structure.
RESULTS: 15,311 unique variants were identified, of which 245 occurred in coding regions. With the unified IT-framework, 132 variants were identified and 87 functionally significant VUS were further prioritized. An intragenic 32.1 kb interval in BRCA2 that was likely hemizygous was detected in one patient. We also identified 4 stop-gain variants and 3 reading-frame altering exonic insertions/deletions (indels).
CONCLUSIONS: We have presented a strategy for complete gene sequence analysis followed by a unified framework for interpreting non-coding variants that may affect gene expression. This approach distills large numbers of variants detected by NGS to a limited set of variants prioritized as potential deleterious changes.

Baloch AH, Khosa AN, Bangulzai N, et al.
Novel Nonsense Variants c.58C>T (p.Q20X) and c.256G>T (p.E85X) in the CHEK2 Gene Identified dentified in Breast Cancer Patients from Balochistan.
Asian Pac J Cancer Prev. 2016; 17(3):1089-92 [PubMed] Related Publications
Breast cancer is the most commonly occurring and leading cause of cancer deaths among women globally. Hereditary cases account 5-10% of all the cases and CHEK2 is considered as a moderate penetrance breast cancer risk gene. CHEK2 plays a crucial role in response to DNA damage to promote cell cycle arrest and repair DNA damage or induce apoptosis. Our objective in the current study was to analyze mutations in the CHEK2 gene related to breast cancer in Balochistan. A total of 271 individuals including breast cancer patients and normal subjects were enrolled. All 14 exons of CHEK2 were amplified and sequenced. The majority of the patients (>95%) had invasive ductal carcinomas (IDCs), 52.1% were diagnosed with tumor grade III and 56.1% and 27.5% were diagnosed with advance stages III and IV. Two novel nonsense variants i.e. c.58C>T (P.Q20X) and c.256G>T (p.E85X) at exon 1 and 2 in two breast cancer patients were identified in the current study. Both the variants identified were novel and have not been reported elsewhere.

Tan X, Liu P, Huang Y, et al.
Phosphoproteome Analysis of Invasion and Metastasis-Related Factors in Pancreatic Cancer Cells.
PLoS One. 2016; 11(3):e0152280 [PubMed] Free Access to Full Article Related Publications
Mechanisms of abnormal protein phosphorylation that regulate cell invasion and metastasis in pancreatic cancer remain obscure. In this study, we used high-throughput phosphorylation array to test two pancreatic cancer cell lines (PC-1 cells with a low, and PC-1.0 cells with a high potential for invasion and metastasis). We noted that a total of 57 proteins revealed a differential expression (fold change ≥ 2.0). Six candidate proteins were further validated by western blot with results found to be accordance with the array. Of 57 proteins, 32 up-regulated proteins (e.g. CaMK1-α and P90RSK) were mainly involved in ErbB and neurotrophin signaling pathways as determined using DAVID software, while 25 down-regulated proteins (e.g. BID and BRCA1) were closely involved in apoptosis and p53 signaling pathways. Moreover, four proteins (AKT1, Chk2, p53 and P70S6K) with different phosphorylation sites were found, not only among up-regulated, but also among down-regulated proteins. Importantly, specific phosphorylation sites can affect cell biological functions. CentiScaPe software calculated topological characteristics of each node in the protein-protein interaction (PPI) network: we found that AKT1 owns the maximum node degrees and betweenness in the up-regulation protein PPI network (26 nodes, average path length: 1.89, node degrees: 6.62±4.18, betweenness: 22.23±35.72), and p53 in the down-regulation protein PPI network (17 nodes, average path length: 2.04, node degrees: 3.65±2.47, betweenness: 16.59±29.58). In conclusion, the identification of abnormal protein phosphorylation related to invasion and metastasis may allow us to identify new biomarkers in an effort to develop novel therapeutic drug targets for pancreatic cancer treatment.

Huszno J, Budryk M, Kołosza Z, et al.
A Comparison between CHEK2*1100delC/I157T Mutation Carrier and Noncarrier Breast Cancer Patients: A Clinicopathological Analysis.
Oncology. 2016; 90(4):193-8 [PubMed] Related Publications
OBJECTIVE: The suppressor gene CHEK2 encodes a cell cycle checkpoint kinase, involved in cell cycle regulation, apoptosis and response to DNA damage. The aim of this study was to analyze the differences between CHEK2 mutation carriers (CHEK2*1100delC/I157T) and noncarriers with respect to clinicopathological factors.
METHODS: We reviewed the medical records of 100 early breast cancer patients (46 mutation carriers and 54 noncarriers) who were treated with chemotherapy, hormonotherapy or trastuzumab.
RESULTS: CHEK2 mutation carriers were older (>65 years) than noncarriers (17 vs. 7%; p = 0.215). Twenty-five (54%) of them had a history of cancer in the family. Gastric cancer in the family history was detected in 11% of mutation carriers and in 2% of noncarriers (p = 0.092). There was a trend for more frequent lymph node metastases in patients without the mutation in comparison to mutation carriers (46 vs. 28%; p = 0.098). Luminal B type breast cancer was detected more often in carriers (39 vs. 20%; p = 0.048). Breast-conserving treatment was also conducted more often in mutation carriers (57 vs. 31%; p = 0.015). Histologic grades G1/G2 were detected more frequently in mutation carriers (82 vs. 70%; p = 0.212).
CONCLUSION: Mutation carriers were characterized by older age, a history of gastric cancer in the family, locally advanced disease, lower histologic grade and luminal B type breast cancer.

Walsh MF, Nathanson KL, Couch FJ, Offit K
Genomic Biomarkers for Breast Cancer Risk.
Adv Exp Med Biol. 2016; 882:1-32 [PubMed] Free Access to Full Article Related Publications
Clinical risk assessment for cancer predisposition includes a three-generation pedigree and physical examination to identify inherited syndromes. Additionally genetic and genomic biomarkers may identify individuals with a constitutional basis for their disease that may not be evident clinically. Genomic biomarker testing may detect molecular variations in single genes, panels of genes, or entire genomes. The strength of evidence for the association of a genomic biomarker with disease risk may be weak or strong. The factors contributing to clinical validity and utility of genomic biomarkers include functional laboratory analyses and genetic epidemiologic evidence. Genomic biomarkers may be further classified as low, moderate or highly penetrant based on the likelihood of disease. Genomic biomarkers for breast cancer are comprised of rare highly penetrant mutations of genes such as BRCA1 or BRCA2, moderately penetrant mutations of genes such as CHEK2, as well as more common genomic variants, including single nucleotide polymorphisms, associated with modest effect sizes. When applied in the context of appropriate counseling and interpretation, identification of genomic biomarkers of inherited risk for breast cancer may decrease morbidity and mortality, allow for definitive prevention through assisted reproduction, and serve as a guide to targeted therapy .

Kwong A, Chen JW, Shin VY
A new paradigm of genetic testing for hereditary breast/ovarian cancers.
Hong Kong Med J. 2016; 22(2):171-7 [PubMed] Related Publications
INTRODUCTION: Genetic risk factors and family history play an important role in breast cancer development. This review aimed to summarise the current genetic testing approach to hereditary breast/ovarian cancer.
METHODS: A systematic literature review was performed by searching the PubMed database. Publications available online until January 2015 that addressed issues related to hereditary breast/ovarian cancer genetic counselling/testing were selected. The search terms used were "familial breast/ovarian cancer", "susceptibility genes", "genetic counselling", and "genetic testing". The data extracted for this review were analysed by the authors, with a focus on genetic testing for hereditary breast/ovarian cancer.
RESULTS: Although a greater proportion of inherited breast/ovarian cancers are due to the BRCA1 and BRCA2 mutations, a number of new genes have emerged as susceptibility candidates, including rare germline mutations in high penetrance genes, such as TP53 and PTEN, and more frequent mutations in moderate/low penetrance genes, such as PALB2, CHEK2 and ATM. Multi-gene testing, if used appropriately, is generally a more cost- and time-effective method than single-gene testing, and may increase the number of patients who can be offered personal surveillance, risk-reduction options, and testing of high-risk family members.
CONCLUSIONS: Recent advances in molecular genetics testing have identified a number of susceptibility genes related to hereditary breast and/or ovarian cancers other than BRCA1 and BRCA2. The introduction of multi-gene testing for hereditary cancer has revolutionised the clinical management of high-risk patients and their families. Individuals with hereditary breast/ovarian cancer will benefit from genetic counselling/testing.

Tung N, Lin NU, Kidd J, et al.
Frequency of Germline Mutations in 25 Cancer Susceptibility Genes in a Sequential Series of Patients With Breast Cancer.
J Clin Oncol. 2016; 34(13):1460-8 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
PURPOSE: Testing for germline mutations in BRCA1/2 is standard for select patients with breast cancer to guide clinical management. Next-generation sequencing (NGS) allows testing for mutations in additional breast cancer predisposition genes. The frequency of germline mutations detected by using NGS has been reported in patients with breast cancer who were referred for BRCA1/2 testing or with triple-negative breast cancer. We assessed the frequency and predictors of mutations in 25 cancer predisposition genes, including BRCA1/2, in a sequential series of patients with breast cancer at an academic institution to examine the utility of genetic testing in this population.
METHODS: Patients with stages I to III breast cancer who were seen at a single cancer center between 2010 and 2012, and who agreed to participate in research DNA banking, were included (N = 488). Personal and family cancer histories were collected and germline DNA was sequenced with NGS to identify mutations.
RESULTS: Deleterious mutations were identified in 10.7% of women, including 6.1% in BRCA1/2 (5.1% in non-Ashkenazi Jewish patients) and 4.6% in other breast/ovarian cancer predisposition genes including CHEK2 (n = 10), ATM (n = 4), BRIP1 (n = 4), and one each in PALB2, PTEN, NBN, RAD51C, RAD51D, MSH6, and PMS2. Whereas young age (P < .01), Ashkenazi Jewish ancestry (P < .01), triple-negative breast cancer (P = .01), and family history of breast/ovarian cancer (P = .01) predicted for BRCA1/2 mutations, no factors predicted for mutations in other breast cancer predisposition genes.
CONCLUSION: Among sequential patients with breast cancer, 10.7% were found to have a germline mutation in a gene that predisposes women to breast or ovarian cancer, using a panel of 25 predisposition genes. Factors that predict for BRCA1/2 mutations do not predict for mutations in other breast/ovarian cancer susceptibility genes when these genes are analyzed as a single group. Additional cohorts will be helpful to define individuals at higher risk of carrying mutations in genes other than BRCA1/2.

Huang SW, Chang SH, Mu SW, et al.
Imiquimod activates p53-dependent apoptosis in a human basal cell carcinoma cell line.
J Dermatol Sci. 2016; 81(3):182-91 [PubMed] Related Publications
BACKGROUND: The tumor suppressor p53 controls DNA repair, cell cycle, apoptosis, autophagy and numerous other cellular processes. Imiquimod (IMQ), a synthetic toll-like receptor (TLR) 7 ligand for the treatment of superficial basal cell carcinoma (BCC), eliminates cancer cells by activating cell-mediated immunity and directly inducing apoptosis and autophagy in cancer cells.
OBJECTIVE: To evaluate the role of p53 in IMQ-induced cell death in skin cancer cells.
METHODS: The expression, phosphorylation and subcellular localization of p53 were detected by real-time PCR, luciferase reporter assay, cycloheximide chase analysis, immunoblotting and immunocytochemistry. Using BCC/KMC1 cell line as a model, the upstream signaling of p53 activation was dissected by over-expression of TLR7/8, the addition of ROS scavenger, ATM/ATR inhibitors and pan-caspase inhibitor. The role of p53 in IMQ-induced apoptosis and autophagy was assessed by genetically silencing p53 and evaluated by a DNA content assay, immunoblotting, LC3 puncta detection and acridine orange staining.
RESULTS: IMQ induced p53 mRNA expression and protein accumulation, increased Ser15 phosphorylation, promoted nuclear translocation and up-regulated its target genes in skin cancer cells in a TLR7/8-independent manner. In BCC/KMC1 cells, the induction of p53 by IMQ was achieved through increased ROS production to stimulate the ATM/ATR-Chk1/Chk2 axis but was not mediated by inducing DNA damage. The pharmacological inhibition of ATM/ATR significantly suppressed IMQ-induced p53 activation and apoptosis. Silencing of p53 significantly decreased the IMQ-induced caspase cascade activation and apoptosis but enhanced autophagy. Mutant p53 skin cancer cell lines were more resistant to IMQ-induced apoptosis than wildtype p53 skin cancer cell lines.
CONCLUSION: IMQ induced ROS production to stimulate ATM/ATR pathways and contributed to p53-dependent apoptosis in a skin basal cell carcinoma cell line BCC/KMC1.

Mehrian-Shai R, Yalon M, Moshe I, et al.
Identification of genomic aberrations in hemangioblastoma by droplet digital PCR and SNP microarray highlights novel candidate genes and pathways for pathogenesis.
BMC Genomics. 2016; 17:56 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
BACKGROUND: The genetic mechanisms underlying hemangioblastoma development are still largely unknown. We used high-resolution single nucleotide polymorphism microarrays and droplet digital PCR analysis to detect copy number variations (CNVs) in total of 45 hemangioblastoma tumors.
RESULTS: We identified 94 CNVs with a median of 18 CNVs per sample. The most frequently gained regions were on chromosomes 1 (p36.32) and 7 (p11.2). These regions contain the EGFR and PRDM16 genes. Recurrent losses were located at chromosome 12 (q24.13), which includes the gene PTPN11.
CONCLUSIONS: Our findings provide the first high-resolution genome-wide view of chromosomal changes in hemangioblastoma and identify 23 candidate genes: EGFR, PRDM16, PTPN11, HOXD11, HOXD13, FLT3, PTCH, FGFR1, FOXP1, GPC3, HOXC13, HOXC11, MKL1, CHEK2, IRF4, GPHN, IKZF1, RB1, HOXA9, and micro RNA, such as hsa-mir-196a-2 for hemangioblastoma pathogenesis. Furthermore, our data implicate that cell proliferation and angiogenesis promoting pathways may be involved in the molecular pathogenesis of hemangioblastoma.

Kralovicova J, Knut M, Cross NC, Vorechovsky I
Exon-centric regulation of ATM expression is population-dependent and amenable to antisense modification by pseudoexon targeting.
Sci Rep. 2016; 6:18741 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
ATM is an important cancer susceptibility gene that encodes a critical apical kinase of the DNA damage response (DDR) pathway. We show that a key nonsense-mediated RNA decay switch exon (NSE) in ATM is repressed by U2AF, PUF60 and hnRNPA1. The NSE activation was haplotype-specific and was most promoted by cytosine at rs609621 in the NSE 3' splice-site (3'ss), which is predominant in high cancer risk populations. NSE levels were deregulated in leukemias and were influenced by the identity of U2AF35 residue 34. We also identify splice-switching oligonucleotides (SSOs) that exploit competition of adjacent pseudoexons to modulate NSE levels. The U2AF-regulated exon usage in the ATM signalling pathway was centred on the MRN/ATM-CHEK2-CDC25-cdc2/cyclin-B axis and preferentially involved transcripts implicated in cancer-associated gene fusions and chromosomal translocations. These results reveal important links between 3'ss control and ATM-dependent responses to double-strand DNA breaks, demonstrate functional plasticity of intronic variants and illustrate versatility of intronic SSOs that target pseudo-3'ss to modify gene expression.

Catts ZA, Baig MK, Milewski B, et al.
Statewide Retrospective Review of Familial Pancreatic Cancer in Delaware, and Frequency of Genetic Mutations in Pancreatic Cancer Kindreds.
Ann Surg Oncol. 2016; 23(5):1729-35 [PubMed] Related Publications
BACKGROUND: Considering the typical rapid progression and high mortality of pancreatic cancer (PC), early detection may lead to an improved outcome. To date, there is no safe, sensitive, and cost-effective screening strategy to detect PC. Currently, screening is focused on individuals at the highest risk of developing PC based on family history. A high-risk individual is defined as having two or more first-degree relatives with PC, or one first- or second-degree relative with PC with a confirmed mutation in a gene associated with PC. The BRCA2 gene is one of the most common genes linked to pancreatic-only cancer families; however, other hereditary cancer syndromes have also been associated with an increased risk for PC.
METHODS: We conducted a retrospective review of pedigrees of families with a pancreatic adenocarcinoma cancer diagnosis held in the statewide Ruth Ann Minner High Risk Family Cancer Registry at the Helen F. Graham Cancer Center and Research Institute, Christiana Care Health System, Newark, DE, USA, from 2002 to 2013. The registry was queried based on how many first-, second-, or third-degree relatives of the proband were affected with PC, genetic testing status, and (if applicable) the results. These data were then categorized into families that meet familial PC (FPC) criteria, defined as two first-degree relatives with PC (FPC families), families that did not meet the FPC definition but had one first-degree relative affected with PC (first-degree families), and probands with PC (probands). Each family was counted only once in the analysis, even if multiple family members were tested.
RESULTS: Our analysis revealed that 175 of 597 families fitting any of the above criteria completed genetic testing. Of this cohort, 52 had pathogenic alterations with nine different genes implicated. Overall, 164 of the 175 families that fitted into any of the three categories previously identified had BRCA1 or BRCA2 testing, either by DNA sequencing or next-generation sequencing via a panel test that included BRCA1/2. BRCA1 pathogenic alterations were noted in 17/164 (10.4 %) and BRCA2 pathogenic alterations were noted in 23/164 (14.0 %). FPC families (n = 46) 42/46 of the FPC families underwent BRCA1/2 testing, and 11/42 (26 % [95 % CI 12.89-39.49]) had pathogenic alterations. Specifically, 4/42 = BRCA1 (9.5 %) and 7/42 = BRCA2 (16.7 %). Additionally, 16/46 of the FPC families underwent exclusively Lynch syndrome (LS) testing, and pathogenic mutations in a mismatch repair protein were identified in 2/16. Specifically, 1/16 = MLH1 (6.3 %) and 1/16 = MSH2 (3.6 %). Overall, a genetic mutation within any gene associated with an increased PC risk was found in 28 % of FPC families. First-degree families (n = 106) 99/106 of the families with one first-degree relative underwent BRCA1/2 testing, and 21/99 (21.2 % [95 % CI 13.16-29.27]) had pathogenic alterations. Specifically, 11/99 = BRCA1 (11.1 %) and 10/99 = BRCA2 (10.1 %). 32/99 first-degree families underwent exclusively LS testing, and pathogenic mutations were identified in 4/32. Specifically, 3/32 = MLH1 (9 %) and 1/32 = MSH6 (3 %). 25/99 of the families pursued panel testing, and pathogenic alterations in any gene were identified in 3/25. Specifically, the mutations were found in 1/25 = ATM (4 %), 1/25 = CHEK2 (4 %), and 1/25 = RAD51D (4 %). Affected probands (n = 23) Lastly, all 23 probands affected with PC pursued genetic testing. Of these, 11/23 were found to have pathogenic alterations. All 23 underwent BRCA1/2 testing, and pathogenic alterations were identified in 8/23 (35 % [95 % CI 15.32-54.25]), specifically 2/23 = BRCA1 (9 %), and 6/23 = BRCA2 (26 %). 10/23 patients underwent panel testing and pathogenic alterations were found in 3/10 (30 %) patients, of whom 1/10 = MSH6 (10 %), 1/10 = ATM (10 %), and 1/10 = TP53 (10 %).
CONCLUSIONS: This study demonstrates that a statewide high-risk family cancer registry is an important instrument in studying the risk of PC in families. Our analysis revealed 14 mutations associated with FPC, among which hereditary breast and ovarian cancer and LS were most prevalent. BRCA1 was found to have the same association with PC as BRCA2, which appears unique to our population. We plan to use our knowledge of these mutations in developing a PC screening program.

Bernards SS, Norquist BM, Harrell MI, et al.
Genetic characterization of early onset ovarian carcinoma.
Gynecol Oncol. 2016; 140(2):221-5 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
OBJECTIVE: Ovarian carcinoma (OC) is rare in young women and the fraction of early onset OC attributable to inherited mutations in known OC genes is uncertain. We sought to characterize the fraction of OC that is heritable in women diagnosed with ovarian, fallopian tube, or peritoneal carcinoma at forty years of age or younger.
METHODS: We sequenced germline DNA from forty-seven women diagnosed with OC at age 40 or younger ascertained through a gynecologic oncology tissue bank or referred from outside providers using BROCA, a targeted capture and massively parallel sequencing platform that can detect all mutation classes. We evaluated 11 genes associated with ovarian carcinoma (BARD1, BRCA1, BRCA2, BRIP1, MLH1, MSH2, MSH6, PALB2, PMS2, RAD51D, and RAD51C) and additional candidate genes in DNA repair (ATM, BAP1, CHEK2, MRE11A, NBN, PTEN, TP53). We counted only clearly damaging mutations.
RESULTS: Damaging mutations in OC genes were identified in 13 of 47 (28%) subjects, of which 10 (77%) occurred in BRCA1 and one each occurred in BRCA2, MSH2, and RAD51D. Women with a strong family history were no more likely to have an OC gene mutation (8/17, 47%) than those without a strong family history (9/30, 30%, P=0.35). Additionally, damaging mutations in non-OC genes were identified, one in NBN and one in CHEK2.
CONCLUSIONS: A high proportion of young women with invasive OC have mutations in BRCA1, and a smaller fraction have mutations in other known OC genes. Family history was not associated with mutation status in these early onset cases.

Wu F, Chen WJ, Yan L, et al.
Mus81 knockdown improves chemosensitivity of hepatocellular carcinoma cells by inducing S-phase arrest and promoting apoptosis through CHK1 pathway.
Cancer Med. 2016; 5(2):370-85 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
As a critical endonuclease in DNA repair, Mus81 is traditionally regarded as a tumor suppressor, but recently correlated with the sensitivity of mitomycin C and 5-fluorouracil in colon cancer and breast cancer cells. However, its role in chemosensitivity of other human malignancies still remains unknown. This study therefore aims to investigate the effects of Mus81 knockdown on the chemosensitivity of hepatocellular carcinoma (HCC), a usually chemorefractory tumor, and explore the underlying mechanisms. Mus81 expression in HepG2 and Bel-7402 HCC cell lines was depleted by lentivirus-mediated short hairpin RNA and the elevated sensitivity of these Mus81-inhibited HCC cells to therapeutic agents, especially to epirubicin (EPI), was evidenced by MTT assay and an HCC chemotherapy mouse model. Flow cytometric analysis also showed that Mus81 knockdown lead to an obvious S-phase arrest and an elevated apoptosis in EPI-treated HepG2 and Bel-7402 cells, which could be rescued by CHK1 inhibition. The activation of CHK1/CDC25A/CDK2 pathway was also demonstrated in Mus81-inhibited HepG2 cells and xenograft mouse tumors under EPI treatment. Meanwhile, the apoptosis of HepG2 cells in response to EPI was remarkably promoted by Mus81 knockdown through activating p53/Bax/Caspase-3 pathway under the controlling of CHK1. In addition, CHK2 inhibition slightly raised CHK1 activity, thereby enhancing the S-phase arrest and apoptosis induced by EPI in Mus81-suppressed HCC cells. In conclusion, Mus81 knockdown improves the chemosensitivity of HCC cells by inducing S-phase arrest and promoting apoptosis through CHK1 pathway, suggesting Mus81 as a novel therapeutic target for HCC.

Macháčková E, Hazova J, Sťahlová Hrabincová E, et al.
[Retrospective NGS Study in High-risk Hereditary Cancer Patients at Masaryk Memorial Cancer Institute].
Klin Onkol. 2016; 29 Suppl 1:S35-45 [PubMed] Related Publications
BACKGROUND: Currently, more than 200 hereditary cancer syndromes have been described, yet, in most countries genetic testing is restricted to a narrow spectrum of genes within a limited group of people tested.
METHODS: For this retrospective study we used the TruSight cancer panel (Illumina)--NGS panel targeting 94 cancer predisposition genes in order to analyze 50 high-risk cancer patients with significant personal and family history of cancer who did not carry mutations in BRCA1, BRCA2, MLH1, MSH2, MSH6, TP53 or APC genes. All pathogenic and potentially pathogenic mutations detected by NGS technology have been confirmed by Sanger sequencing.
RESULTS: There were several deleterious (frame-shift/nonsense) mutations detected in ATM, BAP1, FANCC, FANCI, PMS2, SBDS, ERCC2, RECQL4 genes. Various pathogenic or potentially pathogenic (missense, predicted splice site, in-frame insertion/deletion) mutations were detected in ATM, BRIP1, CDH1, CHEK2, ERCC2, ERCC3, ERCC4, FANCA, MC1R, MEN1, MRE11A, MUTYH, PALB2, RAD51C, RET, SDHB, STK11. These mutations affect highly conserved protein domains and affect their function as proved by the available functional assays. They were confirmed to be pathogenic as an "Parent No2 " in serious recessive diseases such as Ataxia telangiectasia or Fanconi anemia. The clinical significance of the majority of detected missense variants still remains to be identified.
CONCLUSION: Moderate or low penetrance variants are of limited clinical importance. Panel genetic testing in high-risk individuals with cancer provides important information concerning the cause of the investigated cancer, and may assist in the risk assesment and optimal management of the cancer, as well as in further preventive care.

Yablonski-Peretz T, Paluch-Shimon S, Gutman LS, et al.
Screening for germline mutations in breast/ovarian cancer susceptibility genes in high-risk families in Israel.
Breast Cancer Res Treat. 2016; 155(1):133-8 [PubMed] Related Publications
We evaluated the clinical utility of screening for mutations in 34 breast/ovarian cancer susceptibility genes in high-risk families in Israel. Participants were recruited from 12, 2012 to 6, 2015 from 8 medical centers. All participants had high breast/ovarian cancer risk based on personal and family history. Genotyping was performed with the InVitae™ platform. The study was approved by the ethics committees of the participating centers; all participants gave a written informed consent before entering the study. Overall, 282 individuals participated in the study: 149 (53 %) of Ashkenazi descent, 80 (28 %) Jewish non-Ashkenazi descent, 22 (8 %) of mixed Ashkenazi/non-Ashkenazi origin, 21 (7 %) were non-Jewish Caucasians, and the remaining patients (n = 10-3.5 %) were of Christian Arabs/Druze/unknown ethnicity. For breast cancer patients (n = 165), the median (range) age at diagnosis was 46 (22-90) years and for ovarian cancer (n = 15) 54 (38-69) years. Overall, 30 cases (10.6 %) were found to carry a pathogenic actionable mutation in the tested genes: 10 BRCA1 (3 non-founder mutations), 9 BRCA2 (8 non-founder mutations), and one each in the RAD51C and CHEK2 genes. Furthermore, actionable mutations were detected in 9 more cases in 4 additional genes (MSH2, RET, MSH6, and APC). No pathogenic mutations were detected in the other genotyped genes. In this high-risk population, 10.6 % harbored an actionable pathogenic mutation, including non-founder mutations in BRCA1/2 and in additional cancer susceptibility genes, suggesting that high-risk families should be genotyped and be assigned a genotype-based cancer risk.

Kanojia D, Nagata Y, Garg M, et al.
Genomic landscape of liposarcoma.
Oncotarget. 2015; 6(40):42429-44 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Liposarcoma (LPS) is the most common type of soft tissue sarcoma accounting for 20% of all adult sarcomas. Due to absence of clinically effective treatment options in inoperable situations and resistance to chemotherapeutics, a critical need exists to identify novel therapeutic targets. We analyzed LPS genomic landscape using SNP arrays, whole exome sequencing and targeted exome sequencing to uncover the genomic information for development of specific anti-cancer targets. SNP array analysis indicated known amplified genes (MDM2, CDK4, HMGA2) and important novel genes (UAP1, MIR557, LAMA4, CPM, IGF2, ERBB3, IGF1R). Carboxypeptidase M (CPM), recurrently amplified gene in well-differentiated/de-differentiated LPS was noted as a putative oncogene involved in the EGFR pathway. Notable deletions were found at chromosome 1p (RUNX3, ARID1A), chromosome 11q (ATM, CHEK1) and chromosome 13q14.2 (MIR15A, MIR16-1). Significantly and recurrently mutated genes (false discovery rate < 0.05) included PLEC (27%), MXRA5 (21%), FAT3 (24%), NF1 (20%), MDC1 (10%), TP53 (7%) and CHEK2 (6%). Further, in vitro and in vivo functional studies provided evidence for the tumor suppressor role for Neurofibromin 1 (NF1) gene in different subtypes of LPS. Pathway analysis of recurrent mutations demonstrated signaling through MAPK, JAK-STAT, Wnt, ErbB, axon guidance, apoptosis, DNA damage repair and cell cycle pathways were involved in liposarcomagenesis. Interestingly, we also found mutational and copy number heterogeneity within a primary LPS tumor signifying the importance of multi-region sequencing for cancer-genome guided therapy. In summary, these findings provide insight into the genomic complexity of LPS and highlight potential druggable pathways for targeted therapeutic approach.

Churpek JE, Marquez R, Neistadt B, et al.
Inherited mutations in cancer susceptibility genes are common among survivors of breast cancer who develop therapy-related leukemia.
Cancer. 2016; 122(2):304-11 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
BACKGROUND: Risk factors for the development of therapy-related leukemia (TRL), an often lethal late complication of cytotoxic therapy, remain poorly understood and may differ for survivors of different malignancies. Survivors of breast cancer (BC) now account for the majority of TRL cases, making the study of TRL risk factors in this population a priority.
METHODS: Subjects with TRL after cytotoxic therapy for a primary BC were identified from the TRL registry at The University of Chicago. Those with an available germline DNA sample were screened with a comprehensive gene panel covering known inherited BC susceptibility genes. Clinical and TRL characteristics of all subjects and those with identified germline mutations were described.
RESULTS: Nineteen of 88 survivors of BC with TRL (22%) had an additional primary cancer and 40 of the 70 survivors with an available family history (57%) had a close relative with breast, ovarian, or pancreatic cancer. Of the 47 subjects with available DNA, 10 (21%) were found to carry a deleterious inherited mutation in BRCA1 (3 subjects; 6%), BRCA2 (2 subjects; 4%), TP53 (tumor protein p53) (3 subjects; 6%), CHEK2 (checkpoint kinase 2) (1 subject; 2%), and PALB2 (partner and localizer of BRCA2) (1 subject; 2%).
CONCLUSIONS: Survivors of BC with TRL have personal and family histories suggestive of inherited cancer susceptibility and frequently carry germline mutations in BC susceptibility genes. The data from the current study support the role of these genes in TRL risk and suggest that long-term follow-up studies of women with germline mutations who are treated for BC and functional studies of the effects of heterozygous mutations in these genes on bone marrow function after cytotoxic exposures are warranted. Cancer 2016;122:304-311. © 2015 American Cancer Society.

Villacis RA, Miranda PM, Gomy I, et al.
Contribution of rare germline copy number variations and common susceptibility loci in Lynch syndrome patients negative for mutations in the mismatch repair genes.
Int J Cancer. 2016; 138(8):1928-35 [PubMed] Related Publications
In colorectal carcinoma (CRC), 35% of cases are known to have a hereditary component, while a lower proportion (∼ 5%) can be explained by known genetic factors. In this study, copy number variations (CNVs) were evaluated in 45 unrelated patients with clinical hypothesis of Lynch syndrome (Amsterdam or Bethesda criteria); negative for MLH1, MSH2, MSH6, PMS2, CHEK2*1100delC and TP53 pathogenic mutations; aiming to reveal new predisposing genes. Analyses with two different microarray platforms (Agilent 180K and Affymetrix CytoScan HD) revealed 35 rare CNVs covering 67 known genes in 22 patients. Gains (GALNT6 and GALNT11) and losses (SEMA3C) involving the same gene families related to CRC susceptibility were found among the rare CNVs. Segregation analysis performed on four relatives from one family suggested the involvement of GALNT11 and KMT2C in those at risk of developing CRC. Notably, in silico molecular analysis revealed that 61% (41/67) of the genes covered by rare CNVs were associated with cancer, mainly colorectal (17 genes). Ten common SNPs, previously associated with CRC, were genotyped in 39 index patients and 100 sporadic CRC cases. Although no significant, an increased number of risk alleles was detected in the index cases compared with the sporadic CRC patients. None of the SNPs were covered by CNVs, suggesting an independent effect of each alteration in cancer susceptibility. In conclusion, rare germline CNVs and common SNPs may contribute to an increased risk for hereditary CRC in patients with mismatch repair proficiency.

Lu H, Chu Q, Xie G, et al.
Circadian gene expression predicts patient response to neoadjuvant chemoradiation therapy for rectal cancer.
Int J Clin Exp Pathol. 2015; 8(9):10985-94 [PubMed] Article available free on PMC after 01/04/2017 Related Publications
Preoperative neoadjuvant chemoradiation therapy may be useful in patients with operable rectal cancer, but treatment responses are variable. We examined whether expression levels of circadian clock genes could be used as biomarkers to predict treatment response. We retrospectively analyzed clinical data from 250 patients with rectal cancer, treated with neoadjuvant chemoradiation therapy in a single institute between 2011 and 2013. Gene expression analysis (RT-PCR) was performed in tissue samples from 20 patients showing pathological complete regression (pCR) and 20 showing non-pCR. The genes analyzed included six core clock genes (Clock, Per1, Per2, Cry1, Cry2 and Bmal1) and three downstream target genes (Wee1, Chk2 and c-Myc). Patient responses were analyzed through contrast-enhanced pelvic MRI and endorectal ultrasound, and verified by histological assessment. pCR was defined histologically as an absence of tumor cells. Among the 250 included patients, 70.8% showed regression of tumor size, and 18% showed pCR. Clock, Cry2 and Per2 expressions were significantly higher in the pCR group than in the non-pCR group (P<0.05), whereas Per1, Cry1 and Bmal1 expressions did not differ significantly between groups. Among the downstream genes involved in cell cycle regulation, c-Myc showed significantly higher expression in the pCR group (P<0.05), whereas Wee1 and Chk2 expression did not differ significantly between groups. Circadian genes are potential biomarkers for predicting whether a patient with rectal cancer would benefit from neoadjuvant chemoradiation therapy.

Gupta SK, Kizilbash SH, Carlson BL, et al.
Delineation of MGMT Hypermethylation as a Biomarker for Veliparib-Mediated Temozolomide-Sensitizing Therapy of Glioblastoma.
J Natl Cancer Inst. 2016; 108(5) [PubMed] Article available free on PMC after 01/05/2017 Related Publications
BACKGROUND: Sensitizing effects of poly-ADP-ribose polymerase inhibitors have been studied in several preclinical models, but a clear understanding of predictive biomarkers is lacking. In this study, in vivo efficacy of veliparib combined with temozolomide (TMZ) was evaluated in a large panel of glioblastoma multiforme (GBM) patient-derived xenografts (PDX) and potential biomarkers were analyzed.
METHODS: The efficacy of TMZ alone vs TMZ/veliparib was compared in a panel of 28 GBM PDX lines grown as orthotopic xenografts (8-10 mice per group); all tests of statistical significance were two-sided. DNA damage was analyzed by γH2AX immunostaining and promoter methylation of DNA repair gene O6-methylguanine-DNA-methyltransferase (MGMT) by Clinical Laboratory Improvement Amendments-approved methylation-specific polymerase chain reaction.
RESULTS: The combination of TMZ/veliparib statistically significantly extended survival of GBM models (P < .05 by log-rank) compared with TMZ alone in five of 20 MGMT-hypermethylated lines (average extension in median survival = 87 days, range = 20-150 days), while the combination was ineffective in six MGMT-unmethylated lines. In the MGMT promoter-hypermethylated GBM12 line (median survival with TMZ+veliparib = 189 days, 95% confidence interval [CI] = 59 to 289 days, vs TMZ alone = 98 days, 95% CI = 49 to 210 days, P = .04), the profound TMZ-sensitizing effect of veliparib was lost when MGMT was overexpressed (median survival with TMZ+veliparib = 36 days, 95% CI = 28 to 38 days, vs TMZ alone = 35 days, 95% CI = 32 to 37 days, P = .87), and a similar association was observed in two nearly isogenic GBM28 sublines with an intact vs deleted MGMT locus. In comparing DNA damage signaling after dosing with veliparib/TMZ or TMZ alone, increased phosphorylation of damage-responsive proteins (KAP1, Chk1, Chk2, and H2AX) was observed only in MGMT promoter-hypermethylated lines.
CONCLUSION: Veliparib statistically significantly enhances (P < .001) the efficacy of TMZ in tumors with MGMT promoter hypermethylation. Based on these data, MGMT promoter hypermethylation is being used as an eligibility criterion for A071102 (NCT02152982), the phase II/III clinical trial evaluating TMZ/veliparib combination in patients with GBM.

Francies FZ, Wainstein T, De Leeneer K, et al.
BRCA1, BRCA2 and PALB2 mutations and CHEK2 c.1100delC in different South African ethnic groups diagnosed with premenopausal and/or triple negative breast cancer.
BMC Cancer. 2015; 15:912 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
BACKGROUND: Current knowledge of the aetiology of hereditary breast cancer in the four main South African population groups (black, coloured, Indian and white) is limited. Risk assessments in the black, coloured and Indian population groups are challenging because of restricted information regarding the underlying genetic contributions to inherited breast cancer in these populations. We focused this study on premenopausal patients (diagnosed with breast cancer before the age of 50; n = 78) and triple negative breast cancer (TNBC) patients (n = 30) from the four South African ethnic groups. The aim of this study was to determine the frequency and spectrum of germline mutations in BRCA1, BRCA2 and PALB2 and to evaluate the presence of the CHEK2 c.1100delC allele in these patients.
METHODS: In total, 108 South African breast cancer patients underwent mutation screening using a Next-Generation Sequencing (NGS) approach in combination with Multiplex Ligation-dependent Probe Amplification (MLPA) to detect large rearrangements in BRCA1 and BRCA2.
RESULTS: In 13 (12 %) patients a deleterious mutation in BRCA1/2 was detected, three of which were novel mutations in black patients. None of the study participants was found to have an unequivocal pathogenic mutation in PALB2. Two (white) patients tested positive for the CHEK2 c.1100delC mutation, however, one of these also carried a deleterious BRCA2 mutation. Additionally, six variants of unknown clinical significance were identified (4 in BRCA2, 2 in PALB2), all in black patients. Within the group of TNBC patients, a higher mutation frequency was obtained (23.3 %; 7/30) than in the group of patients diagnosed before the age of 50 (7.7 %; 6/78).
CONCLUSION: This study highlights the importance of evaluating germline mutations in major breast cancer genes in all of the South African population groups. This NGS study shows that mutation analysis is warranted in South African patients with triple negative and/or in premenopausal breast cancer.

Ta HQ, Ivey ML, Frierson HF, et al.
Checkpoint Kinase 2 Negatively Regulates Androgen Sensitivity and Prostate Cancer Cell Growth.
Cancer Res. 2015; 75(23):5093-105 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
Prostate cancer is the second leading cause of cancer death in American men, and curing metastatic disease remains a significant challenge. Nearly all patients with disseminated prostate cancer initially respond to androgen deprivation therapy (ADT), but virtually all patients will relapse and develop incurable castration-resistant prostate cancer (CRPC). A high-throughput RNAi screen to identify signaling pathways regulating prostate cancer cell growth led to our discovery that checkpoint kinase 2 (CHK2) knockdown dramatically increased prostate cancer growth and hypersensitized cells to low androgen levels. Mechanistic investigations revealed that the effects of CHK2 were dependent on the downstream signaling proteins CDC25C and CDK1. Moreover, CHK2 depletion increased androgen receptor (AR) transcriptional activity on androgen-regulated genes, substantiating the finding that CHK2 affects prostate cancer proliferation, partly, through the AR. Remarkably, we further show that CHK2 is a novel AR-repressed gene, suggestive of a negative feedback loop between CHK2 and AR. In addition, we provide evidence that CHK2 physically associates with the AR and that cell-cycle inhibition increased this association. Finally, IHC analysis of CHK2 in prostate cancer patient samples demonstrated a decrease in CHK2 expression in high-grade tumors. In conclusion, we propose that CHK2 is a negative regulator of androgen sensitivity and prostate cancer growth, and that CHK2 signaling is lost during prostate cancer progression to castration resistance. Thus, perturbing CHK2 signaling may offer a new therapeutic approach for sensitizing CRPC to ADT and radiation.

Maddaly R, Sahu B, Mohan DK
Genes Associated with Human Cancers: Their Expressions, Features, Functions, and Significance.
Crit Rev Eukaryot Gene Expr. 2015; 25(3):209-38 [PubMed] Related Publications
Various types of cancer continue to be subjects of intense research because of the impact of these diseases and their socioeconomic implications. Also, the complexity involved in the pathogenesis, nature of the triggers, and the progression of cancers is intriguing. An important aspect of cancers is the genetics involved, and studies involving cancer genes contributed immensely in not only understanding cancers better, but also for obtaining useful markers and therapy targets. We review the salient features, functions, and changes in gene expression for 103 carcinoma genes, 20 sarcoma genes, and 36 lymphoma genes. Apart from the three major levels of cancer type, we discuss the implications of altered gene expression at the tissue level as well. The possible uses of these gene functions and expression changes for diagnostic, prognostic, and therapeutic applications are presented. Also, the 159 genes are assessed for their involvement in more than a single cancer and tissue type. Only the p53 gene is commonly implicated in carcinomas, sarcoma and lymphomas. The CHEK2 and ERBB2 (HER2) genes are commonly found to be associated with carcinomas and sarcomas, whereas the MDM2, MSH2, and MSH6 genes are commonly implicated among carcinomas and lymphomas.

Mihailovich M, Bremang M, Spadotto V, et al.
miR-17-92 fine-tunes MYC expression and function to ensure optimal B cell lymphoma growth.
Nat Commun. 2015; 6:8725 [PubMed] Article available free on PMC after 01/05/2017 Related Publications
The synergism between c-MYC and miR-17-19b, a truncated version of the miR-17-92 cluster, is well-documented during tumor initiation. However, little is known about miR-17-19b function in established cancers. Here we investigate the role of miR-17-19b in c-MYC-driven lymphomas by integrating SILAC-based quantitative proteomics, transcriptomics and 3' untranslated region (UTR) analysis upon miR-17-19b overexpression. We identify over one hundred miR-17-19b targets, of which 40% are co-regulated by c-MYC. Downregulation of a new miR-17/20 target, checkpoint kinase 2 (Chek2), increases the recruitment of HuR to c-MYC transcripts, resulting in the inhibition of c-MYC translation and thus interfering with in vivo tumor growth. Hence, in established lymphomas, miR-17-19b fine-tunes c-MYC activity through a tight control of its function and expression, ultimately ensuring cancer cell homeostasis. Our data highlight the plasticity of miRNA function, reflecting changes in the mRNA landscape and 3' UTR shortening at different stages of tumorigenesis.

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