PARP1; poly (ADP-ribose) polymerase 1 (1q41-q42)

Gene Summary

Gene:PARP1; poly (ADP-ribose) polymerase 1
Summary:This gene encodes a chromatin-associated enzyme, poly(ADP-ribosyl)transferase, which modifies various nuclear proteins by poly(ADP-ribosyl)ation. The modification is dependent on DNA and is involved in the regulation of various important cellular processes such as differentiation, proliferation, and tumor transformation and also in the regulation of the molecular events involved in the recovery of cell from DNA damage. In addition, this enzyme may be the site of mutation in Fanconi anemia, and may participate in the pathophysiology of type I diabetes. [provided by RefSeq, Jul 2008]
Databases:OMIM, VEGA, HGNC, Ensembl, GeneCard, Gene
Protein:poly [ADP-ribose] polymerase 1
Updated:14 December, 2014


What does this gene/protein do?
Show (27)


What pathways are this gene/protein implicaed in?
- Apoptotic Signaling in Response to DNA Damage BIOCARTA
- Caspase Cascade in Apoptosis BIOCARTA
- D4-GDI Signaling Pathway BIOCARTA
- FAS signaling pathway ( CD95 ) BIOCARTA
- Opposing roles of AIF in Apoptosis and Cell Survival BIOCARTA
- TNFR1 Signaling Pathway BIOCARTA
Data from KEGG and BioCarta [BIOCARTA terms] via CGAP

Cancer Overview

Research Indicators

Publications Per Year (1989-2014)
Graph generated 14 December 2014 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 14 December, 2014 using data from PubMed, MeSH and CancerIndex

Notable (4)

Scope includes mutations and abnormal protein expression.

Entity Topic PubMed Papers
Breast CancerPARP1 and Breast Cancer View Publications99
Lung CancerPARP1 and Lung Cancer View Publications27
Ovarian CancerPARP1 and Ovarian Cancer View Publications26
MelanomaPARP1 and Melanoma View Publications20

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

Related Links

Latest Publications: PARP1 (cancer-related)

Broustas CG, Lieberman HB
RAD9 enhances radioresistance of human prostate cancer cells through regulation of ITGB1 protein levels.
Prostate. 2014; 74(14):1359-70 [PubMed] Article available free on PMC after 01/10/2015 Related Publications
BACKGROUND: Mouse embryonic stem cells null for Rad9 are sensitive to deleterious effects of ionizing radiation exposure. Likewise, integrin β1 is a known radioprotective factor. Previously, we showed that RAD9 downregulation in human prostate cancer cells reduces integrin β1 protein levels and ectopic expression of Mrad9 restores inherent high levels.
METHODS: We used RNA interference to knockdown Rad9 expression in PC3 and DU145 prostate cancer cells. These cells were then exposed to ionizing radiation, and integrin β1 protein levels were measured by immunoblotting. Survival of irradiated cells was measured by clonogenicity, cell cycle analysis, PARP-1 cleavage, and trypan blue exclusion.
RESULTS: The function of RAD9 in controlling integrin β1 expression is unique and not shared by the other members of the 9-1-1 complex, HUS1 and RAD1. RAD9 or integrin β1 silencing sensitizes DU145 and PC3 cells to ionizing radiation. Irradiation of DU145 cells with low levels of RAD9 induces cleavage of PARP-1 protein. High levels of ionizing radiation have no effect on integrin β1 protein levels. However, when RAD9 downregulation is combined with 10 Gy of ionizing radiation in DU145 or PC3 cells, there is an additional 50% downregulation of integrin β1 compared with levels in unirradiated RAD9 knockdown cells. Finally, PC3 cells growing on fibronectin display increased radioresistance. However, PC3 cells with RAD9 knockdown are no longer protected by fibronectin after treatment with ionizing radiation.
CONCLUSIONS: Downregulation of RAD9 when combined with ionizing radiation results in reduction of ITGB1 protein levels in prostate cancer cells, and increased lethality.

Related: ITGB1 Prostate Cancer

Xiong T, Wei H, Chen X, Xiao H
[Effect of PARP1 inhibitor PJ34 on multi-drug resistance in human multiple myeloma cell line and its relationship with FA/BRCA pathway].
Zhonghua Yi Xue Yi Chuan Xue Za Zhi. 2014; 31(3):312-6 [PubMed] Related Publications
OBJECTIVE: To investigate the effect of PARP1 inhibitor PJ34 on multi-drug resistance in a human multiple myeloma cell line and its connection with FA/BRCA pathway in DNA damage repair.
METHODS: A CCK8 assay was used to measure the inhibition rate. Real-time quantitative PCR was used to detect expression changes of DNA repair genes involved in the FA/BRCA pathway. Western blotting assay was used to detect expression of key protein FANCD2 in the FA/BRCA pathway. Annexin VFITC/PI double staining flow cytometry was used to measure cell apoptosis induced by PJ34. A COMET assay was used to detect the effect of PJ34 on DNA damage repair.
RESULTS: PJ34 could significantly enhance the sensitivity of RPMI8226/R cells to melphalan. The IC50 value of melphalan was dropped from 20.43 mol/L to 7.8 mol/L. PJ34 could inhibit the DNA damage repair, and the effect was related with the inhibition of FA/BRCA pathway. PJ34 and melphalan showed a synergistic effect in promoting the apoptosis of RPMI8226/R cells.
CONCLUSION: PJ34 can reverse the resistance of RPMI8226/R cells to melphalan by inhibiting the FA/BRCA pathway, which in turn can induce suppression of DNA damage repair. Therefore, PJ34 may have clinical value in overcoming the multi-drug resistance of multiple myeloma.

Related: FANCD2 Myeloma Myeloma - Molecular Biology

Martínez-Bosch N, Iglesias M, Munné-Collado J, et al.
Parp-1 genetic ablation in Ela-myc mice unveils novel roles for Parp-1 in pancreatic cancer.
J Pathol. 2014; 234(2):214-27 [PubMed] Related Publications
Pancreatic cancer has a dismal prognosis and is currently the fourth leading cause of cancer-related death in developed countries. The inhibition of poly(ADP-ribose) polymerase-1 (Parp-1), the major protein responsible for poly(ADP-ribosy)lation in response to DNA damage, has emerged as a promising treatment for several tumour types. Here we aimed to elucidate the involvement of Parp-1 in pancreatic tumour progression. We assessed Parp-1 protein expression in normal, preneoplastic and pancreatic tumour samples from humans and from K-Ras- and c-myc-driven mouse models of pancreatic cancer. Parp-1 was highly expressed in acinar cells in normal and cancer tissues. In contrast, ductal cells expressed very low or undetectable levels of this protein, both in a normal and in a tumour context. The Parp-1 expression pattern was similar in human and mouse samples, thereby validating the use of animal models for further studies. To determine the in vivo effects of Parp-1 depletion on pancreatic cancer progression, Ela-myc-driven pancreatic tumour development was analysed in a Parp-1 knock-out background. Loss of Parp-1 resulted in increased tumour necrosis and decreased proliferation, apoptosis and angiogenesis. Interestingly, Ela-myc:Parp-1(-/-) mice displayed fewer ductal tumours than their Ela-myc:Parp-1(+/+) counterparts, suggesting that Parp-1 participates in promoting acinar-to-ductal metaplasia, a key event in pancreatic cancer initiation. Moreover, impaired macrophage recruitment can be responsible for the ADM blockade found in the Ela-myc:Parp-1(-/-) mice. Finally, molecular analysis revealed that Parp-1 modulates ADM downstream of the Stat3-MMP7 axis and is also involved in transcriptional up-regulation of the MDM2, VEGFR1 and MMP28 cancer-related genes. In conclusion, the expression pattern of Parp-1 in normal and cancer tissue and the in vivo functional effects of Parp-1 depletion point to a novel role for this protein in pancreatic carcinogenesis and shed light into the clinical use of Parp-1 inhibitors.

Related: Apoptosis Cancer of the Pancreas Pancreatic Cancer

Pournazari P, Padmore RF, Kosari F, et al.
B-lymphoblastic leukemia/lymphoma: overexpression of nuclear DNA repair protein PARP-1 correlates with antiapoptotic protein Bcl-2 and complex chromosomal abnormalities.
Hum Pathol. 2014; 45(8):1582-7 [PubMed] Related Publications
Poly(ADP-ribose) polymerase-1 (PARP-1) and Bcl-2 are emerging as therapeutic targets in various cancers. The former is a DNA repair protein associated with genomic stability and apoptosis, whereas the latter is an antiapoptotic protein having a DNA repair function through inhibition of PARP-1. Because genomic stability is critical for prognosis in B-lymphoblastic leukemia/lymphoma (B-ALL), we studied the expression of PARP-1 and Bcl-2 proteins in patients with B-ALL of different ages and compared the results with cytogenetic data. The PARP-1 protein was overexpressed in about two-thirds (61%) of patients with B-ALL. It had a nuclear location, whereas Bcl-2 protein was cytosolic. Expression of the 2 proteins showed a highly positive correlation (ρ = 0.367; P < .001). Overexpression of PARP-1 correlated with a complex karyotype (P = .030), and this correlation remained significant for coexpression of PARP-1 and Bcl-2 proteins (χ(2) = 7.498; P = .024) as well as after exclusion of pediatric patients (n = 9, P = .042). Overexpression of PARP-1 was not significantly more common in diploid versus aneuploid karyotypes (50% versus 59%, P = .610). The PARP-1 protein showed no correlation with specific chromosomal abnormalities associated with prognosis in B-ALL, as defined by the World Health Organization. In conclusion, high expression of the PARP-1 protein among patients with B-ALL is related to a complex karyotype and Bcl-2 positivity. Although these findings require validation in a larger population, the observations will be valuable in planning therapeutic trials (such as of PARP inhibitors and BH3 mimetics).

Related: Apoptosis Acute Lymphocytic Leukemia (ALL) Childhood Acute lymphoblastic leukaemia (ALL) ALL - Molecular Biology

Park EJ, Min KJ, Lee TJ, et al.
β-Lapachone induces programmed necrosis through the RIP1-PARP-AIF-dependent pathway in human hepatocellular carcinoma SK-Hep1 cells.
Cell Death Dis. 2014; 5:e1230 [PubMed] Article available free on PMC after 01/10/2015 Related Publications
β-Lapachone activates multiple cell death mechanisms including apoptosis, autophagy and necrotic cell death in cancer cells. In this study, we investigated β-lapachone-induced cell death and the underlying mechanisms in human hepatocellular carcinoma SK-Hep1 cells. β-Lapachone markedly induced cell death without caspase activation. β-Lapachone increased PI uptake and HMGB-1 release to extracellular space, which are markers of necrotic cell death. Necrostatin-1 (a RIP1 kinase inhibitor) markedly inhibited β-lapachone-induced cell death and HMGB-1 release. In addition, β-lapachone activated poly (ADP-ribosyl) polymerase-1(PARP-1) and promoted AIF release, and DPQ (a PARP-1 specific inhibitor) or AIF siRNA blocked β-lapachone-induced cell death. Furthermore, necrostatin-1 blocked PARP-1 activation and cytosolic AIF translocation. We also found that β-lapachone-induced reactive oxygen species (ROS) production has an important role in the activation of the RIP1-PARP1-AIF pathway. Finally, β-lapachone-induced cell death was inhibited by dicoumarol (a NQO-1 inhibitor), and NQO1 expression was correlated with sensitivity to β-lapachone. Taken together, our results demonstrate that β-lapachone induces programmed necrosis through the NQO1-dependent ROS-mediated RIP1-PARP1-AIF pathway.

Related: Liver Cancer Signal Transduction

De Summa S, Pinto R, Pilato B, et al.
Expression of base excision repair key factors and miR17 in familial and sporadic breast cancer.
Cell Death Dis. 2014; 5:e1076 [PubMed] Article available free on PMC after 01/10/2015 Related Publications
Understanding of BRCA1/2 interaction with the base excision repair (BER) pathway could improve therapy based on 'synthetic lethality', whose effectiveness is based on homologous recombination deficiency in cells lacking functional BRCA genes. However, poly (ADP-ribose) polymerase (PARP) inhibitors failed in some patients and for this reason we explored BER key enzyme expression. In this study, the expression of BER enzymes (redox factor 1/apurinic-apyrimidinic endonuclease 1 (REF1/APEX1), NTH endonuclease III-like 1 (NTHL1), 8-oxoguanine DNA glycosylase (OGG1), PARP1) and of the scaffold protein XRCC1 (X-ray repair complementing defective repair in Chinese hamster cells 1) were investigated in familial (BRCA-related and not) and sporadic breast cancer cases. Furthermore, miR17 expression was measured because of its role in the epigenetic regulation of BRCA1. Gene expression was evaluated in BRCA1-mutated cell lines, SUM149PT and SUM1315MO2, and in a BRCA1-proficient triple-negative MDA-MB-231 cell line. A cohort of 27 familial and 16 sporadic breast cancer patients was then examined to confirm results obtained from the cell line model. APEX1/REF1 was found to be upregulated in familial BRCA-wild-type and sporadic cases, indicating this enzyme as a potential therapeutic target. Furthermore, XRCC1 was overexpressed in BRCAX patients; consequently, we suggest to test the effectiveness of inhibitors targeting two different BER components in preclinical studies. XRCC1, which is also involved in the non-homologous end-joining pathway, was found to be downregulated in BRCA2-related patients concurrently with no change in PARP1 expression. Interestingly, no difference in PARP1 and miR17 expression was found in BRCA-related and sporadic breast cancer cases. PARP1 and miR17 could therefore be further investigated as molecular biomarkers of 'BRCAness' phenotype, indicating patients which could really benefit from PARP inhibitor therapies.

Davies JR, Jewell R, Affleck P, et al.
Inherited variation in the PARP1 gene and survival from melanoma.
Int J Cancer. 2014; 135(7):1625-33 [PubMed] Article available free on PMC after 01/10/2015 Related Publications
We report the association of an inherited variant located upstream of the poly(adenosine diphosphate-ribose) polymerase 1 (PARP1) gene (rs2249844), with survival in 11 BioGenoMEL melanoma cohorts. The gene encodes a protein involved in a number of cellular processes including single-strand DNA repair. Survival analysis was conducted for each cohort using proportional hazards regression adjusting for factors known to be associated with survival. Survival was measured as overall survival (OS) and, where available, melanoma-specific survival (MSS). Results were combined using random effects meta-analysis. Evidence for a role of the PARP1 protein in melanoma ulceration and survival was investigated by testing gene expression levels taken from formalin-fixed paraffin-embedded tumors. A significant association was seen for inheritance of the rarer variant of PARP1, rs2249844 with OS (hazard ratio (HR) = 1.16 per allele, 95% confidence interval (CI) 1.04-1.28, p = 0.005, eleven cohorts) and MSS (HR = 1.20 per allele, 95% CI 1.01-1.39, p = 0.03, eight cohorts). We report bioinformatic data supportive of a functional effect for rs2249844. Higher levels of PARP1 gene expression in tumors were shown to be associated with tumor ulceration and poorer OS.

Related: Melanoma

Byrne M, Wray J, Reinert B, et al.
Mechanisms of oncogenic chromosomal translocations.
Ann N Y Acad Sci. 2014; 1310:89-97 [PubMed] Related Publications
Chromosome translocations are caused by inappropriate religation of two DNA double-strand breaks (DSBs) in heterologous chromosomes. These DSBs can be generated by endogenous or exogenous sources. Endogenous sources of DSBs leading to translocations include inappropriate recombination activating gene (RAG) or activation-induced deaminase (AID) activity during immune receptor maturation. Endogenous DSBs can also occur at noncanonical DNA structures or at collapsed replication forks. Exogenous sources of DSBs leading to translocations include ionizing radiation (IR) and cancer chemotherapy. Spatial proximity of the heterologous chromosomes is also important for translocations. While three distinct pathways for DNA DSB repair exist, mounting evidence supports alternative nonhomologous end joining (aNHEJ) as the predominant pathway through which the majority of translocations occur. Initiated by poly (ADP-ribose) polymerase 1 (PARP1), aNHEJ is utilized less frequently in DNA DSB repair than other forms of DSB repair. We recently found that PARP1 is essential for chromosomal translocations to occur and that small molecule PARP1 inhibitors, already in clinical use, can inhibit translocations generated by IR or topoisomerase II inhibition. These data confirm the central role of PARP1 in aNHEJ-mediated chromosomal translocations and raise the possibility of using clinically available PARP1 inhibitors in patients who are at high risk for secondary oncogenic chromosomal translocations.

Mhawech-Fauceglia P, Wang D, Kim G, et al.
Expression of DNA repair proteins in endometrial cancer predicts disease outcome.
Gynecol Oncol. 2014; 132(3):593-8 [PubMed] Related Publications
OBJECTIVE: The consequences of defective homologous recombination and other DNA repair pathways are important in disease outcomes of numerous tumor types. The objective of this study was to explore BRCA1, PARP, FANCD2, PTEN, H2AX, and ATM protein expression in endometrial cancer (EC).
METHODS: PARP1, γH2AX, ATM, FANCD2, PTEN, BRCA1, and p53 proteins were evaluated in EC tissue microarray (TMA) and their expressions were correlated with clinical and pathological parameters in 357 patients.
RESULTS: In type I EC, PARP1(+), ATM(+), and FANCD2(+) were associated with high tumor grade (p 0.031, p 0.0045, p 0.0062 respectively); γH2AX(+) and FANCD2(+) with advanced tumor stage (p 0.0004, p 0.0085 respectively); γH2AX(+), FANCD2(+) and p53(+) with the presence of lympho-vascular invasion (p 0.0004, p 0.0042, p 0.0098 respectively); and γH2AX(+) and ATM(+) with tumor recurrence (p 0.0203, p 0.0465) respectively. In type II EC, only PARP1(+) was associated with tumor stage (p 0.0499). EC patients with p53(+) or FANCD2(+) were more likely to recur with 5year recurrence free survival (RFS) probability of 71.4% in comparison to 85.5% for the other patients and they were more likely to have shorter 5year overall survival (OS) of 66.46% in comparison to 78.5% of those other patients Finally, patients with ATM(+) and p53(+) or FANCD2(+) were more likely to recur with 5year RFS probability of 68% versus 80.3% for the other patients.
CONCLUSION: DNA repair proteins seemed to play an important role in EC, and their expressions can forecast for poor outcomes.

Related: Endometrial (Uterus) Cancer Endometrial Cancer FANCD2 PTEN

Prensner JR, Chen W, Iyer MK, et al.
PCAT-1, a long noncoding RNA, regulates BRCA2 and controls homologous recombination in cancer.
Cancer Res. 2014; 74(6):1651-60 [PubMed] Article available free on PMC after 15/03/2015 Related Publications
Impairment of double-stranded DNA break (DSB) repair is essential to many cancers. However, although mutations in DSB repair proteins are common in hereditary cancers, mechanisms of impaired DSB repair in sporadic cancers remain incompletely understood. Here, we describe the first role for a long noncoding RNA (lncRNA) in DSB repair in prostate cancer. We identify PCAT-1, a prostate cancer outlier lncRNA, which regulates cell response to genotoxic stress. PCAT-1 expression produces a functional deficiency in homologous recombination through its repression of the BRCA2 tumor suppressor, which, in turn, imparts a high sensitivity to small-molecule inhibitors of PARP1. These effects reflected a posttranscriptional repression of the BRCA2 3'UTR by PCAT-1. Our observations thus offer a novel mechanism of "BRCAness" in sporadic cancers.

Related: Prostate Cancer

Cincinelli R, Musso L, Merlini L, et al.
7-Azaindole-1-carboxamides as a new class of PARP-1 inhibitors.
Bioorg Med Chem. 2014; 22(3):1089-103 [PubMed] Related Publications
7-Azaindole-1-carboxamides were designed as a new class of PARP-1 inhibitors. The compounds displayed a variable pattern of target inhibition profile that, in part, paralleled the antiproliferative activity in cell lines characterized by homologous recombination defects. A selected compound (1l; ST7710AA1) showed significant in vitro target inhibition and capability to substantially bypass the multidrug resistance mediated by Pgp. In antitumor activity studies against the MX1 human breast carcinoma growth in nude mice, the compound exhibited an effect similar to that of Olaparib in terms of tumor volume inhibition when used at a lower dose than the reference compound. Treatment was well tolerated, as no deaths or significant weight losses were observed among the treated animals.

Related: Breast Cancer

Alanazi M, Pathan AA, Abduljaleel Z, et al.
Association between PARP-1 V762A polymorphism and breast cancer susceptibility in Saudi population.
PLoS One. 2013; 8(12):e85541 [PubMed] Article available free on PMC after 15/03/2015 Related Publications
Genetic aberrations of DNA repair enzymes are known to be common events and to be associated with different cancer entities. Aim of the following study was to analyze the genetic association of rs1136410 (Val762Ala) in PARP1 gene with the risk of breast cancer using genotypic assays and insilico structural predictions. Genotypic analysis of individual locus showed statistically significant association of Val762Ala with increased susceptibility to breast cancer. Protein structural analysis was performed with Val762Ala variant allele and compared with the predicted native protein structure. Protein prediction analysis showed that this nsSNP may cause changes in the protein structure and it is associated with the disease. In addition to the native and mutant 3D structures of PARP1 were also analyzed using solvent accessibility models for further protein stability confirmation. Taken together, this the first study that confirmed Val762Ala variant has functional effect and structural impact on the PARP1 and may play an important role in breast cancer progression in Saudi population.

Related: Breast Cancer

Xia Q, Cai Y, Peng R, et al.
The CDK1 inhibitor RO3306 improves the response of BRCA-proficient breast cancer cells to PARP inhibition.
Int J Oncol. 2014; 44(3):735-44 [PubMed] Related Publications
Breast cancer is one of the most common malignancies in women. Approximately 15% of the patients belong to the triple-negative breast cancer (TNBC) group, and have the disadvantage of not benefiting from currently available receptor-targeted systemic therapies. Some cancers in the TNBC group harbor defects in DNA double-strand break repair by homologous recombination (HR), such as BRCA1 dysfunction, and are hypersensitive to poly (ADP-ribose) polymerase (PARP) inhibition. However, only a small fraction of the tumors are BRCA-deficient, and this restricts the therapeutic utility of the PARP inhibitor monotherapy. Cyclin-dependent kinase 1 (CDK1) is necessary not only for BRCA1-mediated S phase checkpoint activation, but also for HR, because it phosphorylates BRCA1 for the efficient formation of BRCA1 foci. In this study, we showed that the combined inhibition of CDK1 and PARP in BRCA-proficient MDA-MB-231 breast cancer cells resulted in dramatically reduced cell growth compared to PARP inhibition alone. Mechanistic investigations revealed that this sensitivity appears to be mediated by sustained DNA damage and inefficient DNA repair triggering mitochondrial-mediated apoptosis as well as autophagy. Our results suggest that CDK1 inhibition represents a plausible strategy for expanding the utility of PARP inhibitors to BRCA‑proficient breast cancers.

Yang L, Huang K, Li X, et al.
Identification of poly(ADP-ribose) polymerase-1 as a cell cycle regulator through modulating Sp1 mediated transcription in human hepatoma cells.
PLoS One. 2013; 8(12):e82872 [PubMed] Article available free on PMC after 15/03/2015 Related Publications
The transcription factor Sp1 is implicated in the activation of G0/G1 phase genes. Modulation of Sp1 transcription activities may affect G1-S checkpoint, resulting in changes in cell proliferation. In this study, our results demonstrated that activated poly(ADP-ribose) polymerase 1 (PARP-1) promoted cell proliferation by inhibiting Sp1 signaling pathway. Cell proliferation and cell cycle assays demonstrated that PARP inhibitors or PARP-1 siRNA treatment significantly inhibited proliferation of hepatoma cells and induced G0/G1 cell cycle arrest in hepatoma cells, while overexpression of PARP-1 or PARP-1 activator treatment promoted cell cycle progression. Simultaneously, inhibition of PARP-1 enhanced the expression of Sp1-mediated checkpoint proteins, such as p21 and p27. In this study, we also showed that Sp1 was poly(ADP-ribosyl)ated by PARP-1 in hepatoma cells. Poly(ADP-ribosyl)ation suppressed Sp1 mediated transcription through preventing Sp1 binding to the Sp1 response element present in the promoters of target genes. Taken together, these data indicated that PARP-1 inhibition attenuated the poly(ADP-ribosyl)ation of Sp1 and significantly increased the expression of Sp1 target genes, resulting in G0/G1 cell cycle arrest and the decreased proliferative ability of the hepatoma cells.

Related: CDKN1A Liver Cancer

Bailey ML, O'Neil NJ, van Pel DM, et al.
Glioblastoma cells containing mutations in the cohesin component STAG2 are sensitive to PARP inhibition.
Mol Cancer Ther. 2014; 13(3):724-32 [PubMed] Article available free on PMC after 01/03/2015 Related Publications
Recent data have identified STAG2, a core subunit of the multifunctional cohesin complex, as a highly recurrently mutated gene in several types of cancer. We sought to identify a therapeutic strategy to selectively target cancer cells harboring inactivating mutations of STAG2 using two independent pairs of isogenic glioblastoma cell lines containing either an endogenous mutant STAG2 allele or a wild-type STAG2 allele restored by homologous recombination. We find that mutations in STAG2 are associated with significantly increased sensitivity to inhibitors of the DNA repair enzyme PARP. STAG2-mutated, PARP-inhibited cells accumulated in G2 phase and had a higher percentage of micronuclei, fragmented nuclei, and chromatin bridges compared with wild-type STAG2 cells. We also observed more 53BP1 foci in STAG2-mutated glioblastoma cells, suggesting that these cells have defects in DNA repair. Furthermore, cells with mutations in STAG2 were more sensitive than cells with wild-type STAG2 when PARP inhibitors were used in combination with DNA-damaging agents. These data suggest that PARP is a potential target for tumors harboring inactivating mutations in STAG2, and strongly recommend that STAG2 status be determined and correlated with therapeutic response to PARP inhibitors, both prospectively and retrospectively, in clinical trials.

Cai F, Ge I, Wang M, et al.
Pyrosequencing analysis of BRCA1 methylation level in breast cancer cells.
Tumour Biol. 2014; 35(4):3839-44 [PubMed] Related Publications
BRCA1 and BRCA2 genes are crucial for double-strand break repair by homologous recombination, and mutations in these genes are responsible for most familial breast carcinomas. Cells with inactivating mutations of the BRCA1 or BRCA2 tumor suppressor genes are sensitive to poly (ADP-ribose) polymerase-1 (PARP1) inhibitors. Already in 2010, it has been predicted, that BRCA1 hypermethylation might be sensitive to PARP1 inhibitor. However, till today, a statistically significant proof has been missing, and the effectiveness of PARP1 inhibitors for breast cancer caused by BRCA1 promoter hypermethylation remained elusive. Pyrosequencing has been proposed as an optimal method to investigate the methylation status of the BRCA1 genes. Here, we show for the first time that BRCA1 CpG island hypermethylation is sensitive to PARP1 inhibitors. In clinical settings, this might improve treatment response and provide a more personalized therapy for breast cancer patients. Furthermore, the determination of methylation status of BRCA1 and other genes of the BRCA/homologous recombination (HR) pathway may be an important predictive classifier of response to PARP inhibitor therapy.

Related: Breast Cancer BRCA1

Lisiak N, Paszel-Jaworska A, Bednarczyk-Cwynar B, et al.
Methyl 3-hydroxyimino-11-oxoolean-12-en-28-oate (HIMOXOL), a synthetic oleanolic acid derivative, induces both apoptosis and autophagy in MDA-MB-231 breast cancer cells.
Chem Biol Interact. 2014; 208:47-57 [PubMed] Related Publications
HIMOXOL (methyl 3-hydroxyimino-11-oxoolean-12-en-28-oate) is a synthetic derivative of oleanolic acid (OA). HIMOXOL revealed the highest cytotoxic effect among tested synthetic OA analogs. In this study we focused on elucidating the cytotoxic mechanism of HIMOXOL in MDA-MB-231 breast cancer cells. HIMOXOL reduced MDA-MB-231 cell viability with an IC50 value of 21.08±0.24μM. In contrast to OA, the tested compound induced cell death by activating apoptosis and the autophagy pathways. More specifically, we found that HIMOXOL was able to activate the extrinsic apoptotic pathway, which was proven by observation of caspase-8, caspase-3 and PARP-1 protein activation in Western blot analysis. An increase in the ratio of Bax/Bcl-2 protein levels was also detected. Moreover, HIMOXOL triggered microtubule-associated protein LC3-II expression and upregulated beclin 1. This observed compound activity was modulated by mitogen-activated protein kinases and NFκB/p53 signaling pathways. Together, these data suggest that HIMOXOL, a synthetic oleanolic acid derivative which activates dual cell death machineries, could be a potential and novel chemotherapeutic agent.

Related: Apoptosis Breast Cancer CASP3 Signal Transduction

Bajrami I, Frankum JR, Konde A, et al.
Genome-wide profiling of genetic synthetic lethality identifies CDK12 as a novel determinant of PARP1/2 inhibitor sensitivity.
Cancer Res. 2014; 74(1):287-97 [PubMed] Related Publications
Small-molecule inhibitors of PARP1/2, such as olaparib, have been proposed to serve as a synthetic lethal therapy for cancers that harbor BRCA1 or BRCA2 mutations. Indeed, in clinical trials, PARP1/2 inhibitors elicit sustained antitumor responses in patients with germline BRCA gene mutations. In hypothesizing that additional genetic determinants might direct use of these drugs, we conducted a genome-wide synthetic lethal screen for candidate olaparib sensitivity genes. In support of this hypothesis, the set of identified genes included known determinants of olaparib sensitivity, such as BRCA1, RAD51, and Fanconi's anemia susceptibility genes. In addition, the set included genes implicated in established networks of DNA repair, DNA cohesion, and chromatin remodeling, none of which were known previously to confer sensitivity to PARP1/2 inhibition. Notably, integration of the list of candidate sensitivity genes with data from tumor DNA sequencing studies identified CDK12 deficiency as a clinically relevant biomarker of PARP1/2 inhibitor sensitivity. In models of high-grade serous ovarian cancer (HGS-OVCa), CDK12 attenuation was sufficient to confer sensitivity to PARP1/2 inhibition, suppression of DNA repair via homologous recombination, and reduced expression of BRCA1. As one of only nine genes known to be significantly mutated in HGS-OVCa, CDK12 has properties that should confirm interest in its use as a biomarker, particularly in ongoing clinical trials of PARP1/2 inhibitors and other agents that trigger replication fork arrest.

Related: Ovarian Cancer CDK12 gene

Lee JM, Ledermann JA, Kohn EC
PARP Inhibitors for BRCA1/2 mutation-associated and BRCA-like malignancies.
Ann Oncol. 2014; 25(1):32-40 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
Poly(ADP-ribose)polymerase inhibitors (PARPis) have shown promising activity in patients with BRCA1/2 mutation-associated (BRCA1/2(MUT+)) ovarian and breast cancers. Accumulating evidence suggests that PARPi may have a wider application in the treatment of sporadic high-grade serous ovarian cancer, and cancers defective in DNA repair pathways, such as prostate, endometrial, and pancreatic cancers. Several PARPis are currently in phase 1/2 clinical investigation, with registration trials now being designed. Olaparib, one of the most studied PARPis, has demonstrated activity in BRCA1/2(MUT+) and BRCA-like sporadic ovarian and breast cancers, and looks promising in prostate and pancreatic cancers. Understanding more about the molecular abnormalities involved in BRCA-like tumors, exploring novel therapeutic trial strategies and drug combinations, and defining potential predictive biomarkers, is critical to rapidly advancing the field of PARPi therapy and improve clinical outcomes.

Related: Cancer Prevention and Risk Reduction

Hu Y, Zhou M, Li K, et al.
Two DNA repair gene polymorphisms on the risk of gastrointestinal cancers: a meta-analysis.
Tumour Biol. 2014; 35(3):1715-25 [PubMed] Related Publications
PARP-1 and MGMT play an important role in the DNA repair system and therefore have been implicated in human carcinogenesis. However, the association between the most studied PARP-1 rs1136410: T > C and MGMT rs12917: C > T polymorphism and risk of gastrointestinal (GI) cancers was reported with inconclusive results. Accordingly, a meta-analysis of 23 published case-control studies was conducted to assess the strength of association using crude odds ratios (ORs) with 95% confidence intervals (CIs). Overall, the C allele of PARP-1 rs1136410: T > C polymorphism was significantly associated with increased susceptibility of GI cancers (homozygote comparison: OR = 1.43, 95% CI 1.14-1.81; heterozygote comparison: OR = 1.18, 95% CI 1.07-1.29; dominant model: OR = 1.23, 95% CI 1.12-1.35; recessive model: OR = 1.30, 95% CI 1.04-1.62; allelic comparison: OR = 1.19, 95% CI 1.07-1.32). In the subgroup analysis, still obvious associations were found in the Asian population, gastric cancer, and high-quality studies. For MGMT rs12917: C > T polymorphism, no obvious associations were found for all genetic models overall. However, in the subgroup analysis, we found that the T allele was significantly associated with reduced colorectal cancer risk for heterozygote (OR = 0.83, 95% CI 0.70-0.97) and dominant model (OR = 0.84, 95% CI 0.72-0.98). In conclusion, this meta-analysis suggests that the PARP-1 rs1136410: T > C polymorphism is a susceptibility factor for GI cancers, but the variant allele of MGMT rs12917: C > T polymorphism appears to be a protective factor for colorectal cancer. Large-scale and well-designed case-control studies are necessary to validate the risk identified in the present meta-analysis.

Related: Gastrointestinal System Cancers

Zhang L, Wang M, Wang W, Mo J
Incidence and prognostic value of multiple gene promoter methylations in gliomas.
J Neurooncol. 2014; 116(2):349-56 [PubMed] Related Publications
Aberrant CpG island methylation is a common phenomenon in malignancy. The methylation status of multiple tumor suppressor genes may serve as a biomarker for early diagnostics and the prediction of prognosis. In this study, we quantitatively determined the promoter methylation status of five tumor-related genes in tumor tissue and paired serum from 240 patients with gliomas. The relationship between hyper-methylation and clinic-pathological parameters was evaluated, and the prognostic value of the methylation status was determined. Hypermethylation in serum was shown to be accompanied by hypermethylation in paired tumor tissues. In both tumors and serum, methylation of polymerase-1 (PARP-1), SHP-1, DAPK-1 and TIMP-3 genes was at significantly higher levels in high-grade compared with low-grade gliomas, indicating that the promoter methylation status positively correlates with tumor grade. In malignant gliomas, the serum methylation levels of PARP-1, and SHP-1 together with IDH-1 mutations were found to be independent prognostic factors for overall survival. Moreover, hypermethylation of PARP-1 in serum correlated with a shorter progression-free survival time. These results suggest that hypermethylation in gliomas correlates with increased malignancy and poor prognosis. Analysis of the serum promoter methylation status of multiple genes could therefore be used as a biomarker for the detection and evaluation of the prognosis of glioma patients.

Related: IDH1 gene

Jacot W, Thezenas S, Senal R, et al.
BRCA1 promoter hypermethylation, 53BP1 protein expression and PARP-1 activity as biomarkers of DNA repair deficit in breast cancer.
BMC Cancer. 2013; 13:523 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
BACKGROUND: Poly(adenosine diphosphate-ribose) polymerase 1 (PARP-1) and the balance between BRCA1 and 53BP1 play a key role in the DNA repair and cell stress response. PARP inhibitors show promising clinical activity in metastatic triple negative (TN) or BRCA-mutated breast cancer. However, a comprehensive analysis of PARP-1 activity, BRCA1 promoter methylation and 53BP1 expression in tumours without known BRCA1 mutation has not yet been carried out.
METHODS: We investigated cytosolic PARP-1 activity, 53BP1 protein levels and BRCA1 promoter methylation in 155 surgical breast tumour samples from patients without familial breast cancer history or known BRCA1 mutations who were treated between January 2006 and November 2009 and evaluated their statistical association with classical predictive and prognostic factors.
RESULTS: The mitotic count score was the only parameter clearly associated with PARP-1 activity. BRCA1 promoter hypermethylation (15.4% of all cancers) was significantly associated with uPA and PAI-1 levels, tumour grade, mitotic count score, hormone receptor and HER2 negative status and TN profile (29% of TN tumours showed BRCA1 promoter hypermethylation compared to 5% of grade II-III hormone receptor-positive/HER2-negative and 2% of HER2-positive tumours). No statistical association was found between BRCA1 promoter hypermethylation and PARP-1 activity. High 53BP1 protein levels correlated with lymph node positivity, hormone receptor positivity, molecular grouping, unmethylated BRCA1 promoter and PARP-1 activity. In TN tumours, BRCA1 promoter methylation was only marginally associated with age, PARP-1 activity was not associated with any of the tested clinico-pathological factors and high 53BP1 protein levels were significantly associated with lymph node positivity. Only 3 of the 14 TN tumours with BRCA1 promoter hypermethylation presented high 53BP1 protein levels.
CONCLUSIONS: Breast cancers that harbour simultaneously high 53BP1 protein level and BRCA1 promoter hypermethylation and are the putative target population of drugs targeting DNA repair appear to be restricted to a small subgroup of TN tumours.

Related: Breast Cancer Signal Transduction TP53BP1

Steffen JD, Tholey RM, Langelier MF, et al.
Targeting PARP-1 allosteric regulation offers therapeutic potential against cancer.
Cancer Res. 2014; 74(1):31-7 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
PARP-1 is a nuclear protein that has important roles in maintenance of genomic integrity. During genotoxic stress, PARP-1 recruits to sites of DNA damage where PARP-1 domain architecture initiates catalytic activation and subsequent poly(ADP-ribose)-dependent DNA repair. PARP-1 inhibition is a promising new way to selectively target cancers harboring DNA repair deficiencies. However, current inhibitors target other PARPs, raising important questions about long-term off-target effects. Here, we propose a new strategy that targets PARP-1 allosteric regulation as a selective way of inhibiting PARP-1. We found that disruption of PARP-1 domain-domain contacts through mutagenesis held no cellular consequences on recruitment to DNA damage or a model system of transcriptional regulation, but prevented DNA-damage-dependent catalytic activation. Furthermore, PARP-1 mutant overexpression in a pancreatic cancer cell line (MIA PaCa-2) increased sensitivity to platinum-based anticancer agents. These results not only highlight the potential of a synergistic drug combination of allosteric PARP inhibitors with DNA-damaging agents in genomically unstable cancer cells (regardless of homologous recombination status), but also signify important applications of selective PARP-1 inhibition. Finally, the development of a high-throughput PARP-1 assay is described as a tool to promote discovery of novel PARP-1 selective inhibitors.

Related: Cancer of the Pancreas Pancreatic Cancer

Zeng L, You G, Tanaka H, et al.
Combined effects of polymorphisms of DNA-repair protein genes and metabolic enzyme genes on the risk of cholangiocarcinoma.
Jpn J Clin Oncol. 2013; 43(12):1190-4 [PubMed] Related Publications
OBJECTIVE: Although Opisthorchis viverrini is a risk factor for cholangiocarcinoma, not all the infected individuals develop cholangiocarcinoma. We investigated whether the base excision repair enzyme gene polymorphisms with differentiated repair capacities of inflammation-related deoxyribonucleic acid damage may play a key role and such possible effects from those genes may be increased or diminished in co-existence of polymorphisms of metabolic enzymes, including glutathione-S-transferases mu 1 and glutathione-S-transferases θ1.
METHODS: We genotyped five non-synonymous single-nucleotide polymorphisms of three genes, including the human homolog of the 8-oxoguanine glycosylase 1 Ser326Cys, X-ray repair cross-complementing protein 1 Arg194Trp, Arg280His and Arg399Gln and poly (adenosine diphosphate ribose) polymerase 1 Val762Ala in 87-94 matched case-control pairs, and examined relations between those polymorphisms and the risk of cholangiocarcinoma.
RESULTS: Any single polymorphism did not have a measurable association with the risk of cholangiocarcinoma. However, when considering glutathione-S-transferases mu 1 polymorphism together, the human homolog of the 8-oxoguanine glycosylase 1 codon 326 polymorphism was related to the decreased risk; odds ratios were 1.00 (reference), 0.06 (95% confidence interval 0.01-0.53), 0.06 (0.01-0.54) and 0.14 (0.02-1.08) for persons with human homolog of the 8-oxoguanine glycosylase 1 Ser/Ser and glutathione-S-transferases mu 1 wild, ones with Ser/Ser and glutathione-S-transferases mu 1 null, ones with Ser/Cys or Cys/Cys and glutathione-S-transferases mu 1 wild and ones with Ser/Cys or Cys/Cys and glutathione-S-transferases mu 1 null, respectively (P for interaction <0.01). Further adjustment for the presence of anti-Opisthorchis viverrini antibody, smoking and alcohol drinking did not change the decreased risk. Other combinations of deoxyribonucleic acid-repair gene polymorphism and glutathione-S-transferases were not associated with the risk of cholangiocarcinoma.
CONCLUSIONS: The present findings suggested that decreased capacity of deoxyribonucleic acid-repair gene, human homolog of the 8-oxoguanine glycosylase 1, may be related to decreased risk if much damaged cells die before malignant transformation.

Related: Extra-Hepatic Bile duct cancer (cholangiocarcinoma) GSTT1 GSTM1

Michels J, Vitale I, Saparbaev M, et al.
Predictive biomarkers for cancer therapy with PARP inhibitors.
Oncogene. 2014; 33(30):3894-907 [PubMed] Related Publications
Poly(ADP-ribose) polymerase (PARP) inhibitors have raised high expectations for the treatment of multiple malignancies. PARP inhibitors, which can be used as monotherapies or in combination with DNA-damaging agents, are particularly efficient against tumors with defects in DNA repair mechanisms, in particular the homologous recombination pathway, for instance due to BRCA mutations. Thus, deficient DNA repair provides a framework for the success of PARP inhibitors in medical oncology. Here, we review encouraging results obtained in recent clinical trials investigating the safety and efficacy of PARP inhibitors as anticancer agents. We discuss emerging mechanisms of regulation of homologous recombination and how inhibition of DNA repair might be used in cancer therapy. We surmise that the identification of patients that are likely to benefit from PARP inhibition will improve the clinical use of PARP inhibitors in a defined target population. Thus, we will place special emphasis on biomarker discovery.

Related: Cancer Prevention and Risk Reduction

Booth L, Cruickshanks N, Ridder T, et al.
PARP and CHK inhibitors interact to cause DNA damage and cell death in mammary carcinoma cells.
Cancer Biol Ther. 2013; 14(5):458-65 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
The present studies examined viability and DNA damage levels in mammary carcinoma cells following PARP1 and CHK1 inhibitor drug combination exposure. PARP1 inhibitors [AZD2281 ; ABT888 ; NU1025 ; AG014699] interacted with CHK1 inhibitors [UCN-01 ; AZD7762 ; LY2603618] to kill mammary carcinoma cells. PARP1 and CHK1 inhibitors interacted to increase both single strand and double strand DNA breaks that correlated with increased γH2AX phosphorylation. Treatment of cells with CHK1 inhibitors increased the phosphorylation of CHK1 and ERK1/2. Knock down of ATM suppressed the drug-induced increases in CHK1 and ERK1/2 phosphorylation and enhanced tumor cell killing by PARP1 and CHK1 inhibitors. Expression of dominant negative MEK1 enhanced drug-induced DNA damage whereas expression of activated MEK1 suppressed both the DNA damage response and tumor cell killing. Collectively our data demonstrate that PARP1 and CHK1 inhibitors interact to kill mammary carcinoma cells and that increased DNA damage is a surrogate marker for the response of cells to this drug combination.

Related: Apoptosis Breast Cancer Signal Transduction

Fam HK, Walton C, Mitra SA, et al.
TDP1 and PARP1 deficiency are cytotoxic to rhabdomyosarcoma cells.
Mol Cancer Res. 2013; 11(10):1179-92 [PubMed] Related Publications
UNLABELLED: Rhabdomyosarcoma is the most common soft tissue sarcoma in children. Metastatic rhabdomyosarcoma in children has a 5-year event-free survival rate of <30%, and a recent clinical trial with irinotecan, a topoisomerase I inhibitor, failed to improve outcome. Therefore, it was surmised that failure of irinotecan may be the result of overexpression of the DNA repair enzyme tyrosyl-DNA phosphodiesterase (TDP1), which processes topoisomerase I-DNA complexes resulting from topoisomerase I inhibitor treatment. Using human tissue microarrays and gene expression arrays, a marked overexpression of TDP1 protein and mRNA in RMS tumors was observed. Critically, knockdown of TDP1 or inhibition of poly(ADP-ribose) polymerase-1 (PARP-1), an enzyme in the same complex as TDP1, sensitized rhabdomyosarcoma cell lines to analogues of irinotecan. Interestingly, BRCA1/2 mutations or altered expression was not detectable in rhabdomyosarcoma cells; however, TDP1 knockdown and PARP-1 inhibition alone were cytotoxic to a subset of rhabdomyosarcoma cells, suggesting that they harbor genetic lesions in DNA repair components that have synthetic lethal interactions with loss of TDP1 or PARP1 function. Furthermore, culturing embryonal rhabdomyosarcoma cells in serum/nutrient-restricted medium increased cellular cytotoxicity upon PARP-1 inhibition and was intrinsically cytotoxic to alveolar, though not embryonal rhabdomyosarcoma cells. The results of these studies suggest a compensatory role for TDP1 in rhabdomyosarcoma after topoisomerase-I based therapy and further demonstrate that TDP1 knockdown, PARP-1 inhibition, and dietary restriction have therapeutic validity.
IMPLICATIONS: Selective targeting of TDP1 and/or PARP-1 in rhabdomyosarcoma induces cytotoxicity and sensitizes to DNA damaging agents.

Related: Rhabdomyosarcoma

Bey EA, Reinicke KE, Srougi MC, et al.
Catalase abrogates β-lapachone-induced PARP1 hyperactivation-directed programmed necrosis in NQO1-positive breast cancers.
Mol Cancer Ther. 2013; 12(10):2110-20 [PubMed] Article available free on PMC after 01/01/2015 Related Publications
Improving patient outcome by personalized therapy involves a thorough understanding of an agent's mechanism of action. β-Lapachone (clinical forms, Arq501/Arq761) has been developed to exploit dramatic cancer-specific elevations in the phase II detoxifying enzyme NAD(P)H:quinone oxidoreductase (NQO1). NQO1 is dramatically elevated in solid cancers, including primary and metastatic [e.g., triple-negative (ER-, PR-, Her2/Neu-)] breast cancers. To define cellular factors that influence the efficacy of β-lapachone using knowledge of its mechanism of action, we confirmed that NQO1 was required for lethality and mediated a futile redox cycle where ∼120 moles of superoxide were formed per mole of β-lapachone in 2 minutes. β-Lapachone induced reactive oxygen species (ROS), stimulated DNA single-strand break-dependent poly(ADP-ribose) polymerase-1 (PARP1) hyperactivation, caused dramatic loss of essential nucleotides (NAD(+)/ATP), and elicited programmed necrosis in breast cancer cells. Although PARP1 hyperactivation and NQO1 expression were major determinants of β-lapachone-induced lethality, alterations in catalase expression, including treatment with exogenous enzyme, caused marked cytoprotection. Thus, catalase is an important resistance factor and highlights H2O2 as an obligate ROS for cell death from this agent. Exogenous superoxide dismutase enhanced catalase-induced cytoprotection. β-Lapachone-induced cell death included apoptosis-inducing factor (AIF) translocation from mitochondria to nuclei, TUNEL+ staining, atypical PARP1 cleavage, and glyceraldehyde 3-phosphate dehydrogenase S-nitrosylation, which were abrogated by catalase. We predict that the ratio of NQO1:catalase activities in breast cancer versus associated normal tissue are likely to be the major determinants affecting the therapeutic window of β-lapachone and other NQO1 bioactivatable drugs.

Related: Breast Cancer

Shen Y, Rehman FL, Feng Y, et al.
BMN 673, a novel and highly potent PARP1/2 inhibitor for the treatment of human cancers with DNA repair deficiency.
Clin Cancer Res. 2013; 19(18):5003-15 [PubMed] Related Publications
PURPOSE: PARP1/2 inhibitors are a class of anticancer agents that target tumor-specific defects in DNA repair. Here, we describe BMN 673, a novel, highly potent PARP1/2 inhibitor with favorable metabolic stability, oral bioavailability, and pharmacokinetic properties.
EXPERIMENTAL DESIGN: Potency and selectivity of BMN 673 was determined by biochemical assays. Anticancer activity either as a single-agent or in combination with other antitumor agents was evaluated both in vitro and in xenograft cancer models.
RESULTS: BMN 673 is a potent PARP1/2 inhibitor (PARP1 IC50 = 0.57 nmol/L), but it does not inhibit other enzymes that we have tested. BMN 673 exhibits selective antitumor cytotoxicity and elicits DNA repair biomarkers at much lower concentrations than earlier generation PARP1/2 inhibitors (such as olaparib, rucaparib, and veliparib). In vitro, BMN 673 selectively targeted tumor cells with BRCA1, BRCA2, or PTEN gene defects with 20- to more than 200-fold greater potency than existing PARP1/2 inhibitors. BMN 673 is readily orally bioavailable, with more than 40% absolute oral bioavailability in rats when dosed in carboxylmethyl cellulose. Oral administration of BMN 673 elicited remarkable antitumor activity in vivo; xenografted tumors that carry defects in DNA repair due to BRCA mutations or PTEN deficiency were profoundly sensitive to oral BMN 673 treatment at well-tolerated doses in mice. Synergistic or additive antitumor effects were also found when BMN 673 was combined with temozolomide, SN38, or platinum drugs.
CONCLUSION: BMN 673 is currently in early-phase clinical development and represents a promising PARP1/2 inhibitor with potentially advantageous features in its drug class.

Related: Breast Cancer

Shan L, Li X, Liu L, et al.
GATA3 cooperates with PARP1 to regulate CCND1 transcription through modulating histone H1 incorporation.
Oncogene. 2014; 33(24):3205-16 [PubMed] Related Publications
The transcription factor GATA3 is a key regulator of mammary gland development and a definitive marker of luminal breast cancer. However, the molecular mechanisms underlying the role of GATA3 in breast carcinogenesis is still not fully understood. We report here that GATA3 promotes cell proliferation and tumorigenesis by facilitating the G1/S transition through its transcription regulation of the CCND1 gene in breast cancer cells. We found that GATA3 is physically associated with poly-ADP ribose polymerase-1 (PARP1), an enzyme modifying nuclear proteins by poly(ADP-ribosyl)ation. We showed that PARP1 acts as a transcription coactivator for GATA3 in breast cancer cells and demonstrated that GATA3 cooperates with PARP1 in transactivation of the CCND1 gene. We demonstrated that PARP1 competes with linker histone H1 to maintain a transcriptional competent chromatin environment for CCND1 gene. Our results unveiled a molecular basis for the coordinated regulation between GATA3 and PARP1 in transcription activation, providing a mechanism for GATA3 in breast carcinogenesis.

Related: Apoptosis Breast Cancer GATA3 gene BCL1 Gene (CCND1)


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Cite this page: Cotterill SJ. PARP1, Cancer Genetics Web: http://www.cancerindex.org/geneweb/PARP1.htm Accessed: date

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