OCA2

Gene Summary

Gene:OCA2; OCA2 melanosomal transmembrane protein
Aliases: P, BEY, PED, BEY1, BEY2, BOCA, EYCL, HCL3, EYCL2, EYCL3, SHEP1, D15S12
Location:15q12-q13.1
Summary:This gene encodes the human homolog of the mouse p (pink-eyed dilution) gene. The encoded protein is believed to be an integral membrane protein involved in small molecule transport, specifically tyrosine, which is a precursor to melanin synthesis. It is involved in mammalian pigmentation, where it may control skin color variation and act as a determinant of brown or blue eye color. Mutations in this gene result in type 2 oculocutaneous albinism. Alternative splicing results in multiple transcript variants. [provided by RefSeq, Jul 2014]
Databases:VEGA, OMIM, HGNC, Ensembl, GeneCard, Gene
Protein:P protein
Source:NCBIAccessed: 11 March, 2017

Ontology:

What does this gene/protein do?
Show (16)

Cancer Overview

Research Indicators

Publications Per Year (1992-2017)
Graph generated 11 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.

  • Haplotypes
  • Single Nucleotide Polymorphism
  • Case-Control Studies
  • European Continental Ancestry Group
  • Skin Cancer
  • Albinism, Oculocutaneous
  • Polymorphism
  • Pedigree
  • T-Lymphocytes
  • Hair Color
  • Eye Color
  • Membrane Transport Proteins
  • Genetic Variation
  • Genetic Markers
  • Spain
  • Melanoma
  • Genetic Predisposition
  • Surveys and Questionnaires
  • Polymerase Chain Reaction
  • Neoplasm Proteins
  • Genotype
  • Tumor Antigens
  • Risk Factors
  • Melanocytes
  • Guanine Nucleotide Exchange Factors
  • Ultraviolet Rays
  • Skin Pigmentation
  • Multivariate Analysis
  • Squamous Cell Carcinoma
  • Vesicular Transport Proteins
  • Interferon Regulatory Factors
  • Receptor, Melanocortin, Type 1
  • Basal Cell Carcinoma (BCC) - Skin
  • Twins, Monozygotic
  • Pigmentation
  • Genome-Wide Association Study
  • Chromosome 15
  • Phenotype
  • Alleles
Tag cloud generated 11 March, 2017 using data from PubMed, MeSH and CancerIndex

Specific Cancers (3)

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: OCA2 (cancer-related)

Petrushev B, Boca S, Simon T, et al.
Gold nanoparticles enhance the effect of tyrosine kinase inhibitors in acute myeloid leukemia therapy.
Int J Nanomedicine. 2016; 11:641-60 [PubMed] Free Access to Full Article Related Publications
BACKGROUND AND AIMS: Every year, in Europe, acute myeloid leukemia (AML) is diagnosed in thousands of adults. For most subtypes of AML, the backbone of treatment was introduced nearly 40 years ago as a combination of cytosine arabinoside with an anthracycline. This therapy is still the worldwide standard of care. Two-thirds of patients achieve complete remission, although most of them ultimately relapse. Since the FLT3 mutation is the most frequent, it serves as a key molecular target for tyrosine kinase inhibitors (TKIs) that inhibit FLT3 kinase. In this study, we report the conjugation of TKIs onto spherical gold nanoparticles.
MATERIALS AND METHODS: The internalization of TKI-nanocarriers was proved by the strongly scattered light from gold nanoparticles and was correlated with the results obtained by transmission electron microscopy and dark-field microscopy. The therapeutic effect of the newly designed drugs was investigated by several methods including cell counting assay as well as the MTT assay.
RESULTS: We report the newly described bioconjugates to be superior when compared with the drug alone, with data confirmed by state-of-the-art analyses of internalization, cell biology, gene analysis for FLT3-IDT gene, and Western blotting to assess degradation of the FLT3 protein.
CONCLUSION: The effective transmembrane delivery and increased efficacy validate its use as a potential therapeutic.

Fesenko DO, Chudinov AV, Surzhikov SA, Zasedatelev AS
Biochip-Based Genotyping Assay for Detection of Polymorphisms in Pigmentation Genes Associated with Cutaneous Melanoma.
Genet Test Mol Biomarkers. 2016; 20(4):208-12 [PubMed] Related Publications
AIMS: The purpose of the study was to develop a new assay for genotyping nine single nucleotide polymorphisms (SNPs) that are known to be associated with melanoma.
METHODS: Two-stage single tube polymerase chain reaction (PCR) followed by hybridization on a biochip was developed and applied in the study.
RESULTS: A total of nine SNPs were selected from five genes: MC1R (rs1805006, rs1805007, rs1805009, rs11547464), HERC2 (rs12913832), OCA2 (rs1800407), SLC45A2 (rs16891982), TYR (rs1393350), and a SNP from the intergenic locus rs12896399 were used for the synthesis of ssDNAs via a single-stage PCR process. The assays were performed on a biochip-based platform that is capable of SNP genotyping via a single reaction-tube PCR, followed by on chip hybridization. We tested 69 DNAs obtained from healthy persons and demonstrated the assays' ability to discriminate all three genotypes for almost all of the SNPs.
CONCLUSIONS: The developed approach proved robust, suggesting that it might be useful for the personalized genotyping of large cohorts of patients.

Chen C, Ren W, Gao L, et al.
Function of obturator prosthesis after maxillectomy and prosthetic obturator rehabilitation.
Braz J Otorhinolaryngol. 2016 Mar-Apr; 82(2):177-83 [PubMed] Related Publications
INTRODUCTION: Maxillary defects are usually rehabilitated by a prosthetic obturator.
OBJECTIVE: This study aimed to evaluate the functioning of obturators prosthesis in patients with unilateral defects after maxillectomy.
METHODS: Of 49 patients, 28 underwent to maxillectomy as a result of tumor ablative surgery, and acquired unilateral maxillary defects. Evaluation of the function was performed by applying the Obturator Functional Scale (OFS).
RESULTS: From a total of 49 patients, 28 were treated as follows: 9 with a conventional retained obturator prosthesis (COP), 11 (39%) with an enhanced retentive obturator prosthesis with stud attachment (POP) and 8 (28%) with an enhanced retentive obturator prosthesis with magnetic attachment (POM). The mean OFS score was 80. Scores on functions of speech, swallowing and chewing reached statistical significances (p<0.05) among these three subgroups. Comparing COP and MOP groups, the scores of OFS in the domains of "Speech-ability to speak in public" and "Swallowing-leakage with liquids" were significantly higher in AOP group. Comparing COP group, the scores of OFS in "Swallowing-leakage with solid" and "Chewing/eating" domains were increased significantly (p<0.05) both in MOP and AOP groups.
CONCLUSION: Obturator prosthesis improves oral function of patients after maxillary defects; the retention of the obturator prosthesis enhanced by the addition of attachments showed more benefits in oral function.

Tap WD, Wainberg ZA, Anthony SP, et al.
Structure-Guided Blockade of CSF1R Kinase in Tenosynovial Giant-Cell Tumor.
N Engl J Med. 2015; 373(5):428-37 [PubMed] Related Publications
BACKGROUND: Expression of the colony-stimulating factor 1 (CSF1) gene is elevated in most tenosynovial giant-cell tumors. This observation has led to the discovery and clinical development of therapy targeting the CSF1 receptor (CSF1R).
METHODS: Using x-ray co-crystallography to guide our drug-discovery research, we generated a potent, selective CSF1R inhibitor, PLX3397, that traps the kinase in the autoinhibited conformation. We then conducted a multicenter, phase 1 trial in two parts to analyze this compound. In the first part, we evaluated escalations in the dose of PLX3397 that was administered orally in patients with solid tumors (dose-escalation study). In the second part, we evaluated PLX3397 at the chosen phase 2 dose in an extension cohort of patients with tenosynovial giant-cell tumors (extension study). Pharmacokinetic and tumor responses in the enrolled patients were assessed, and CSF1 in situ hybridization was performed to confirm the mechanism of action of PLX3397 and that the pattern of CSF1 expression was consistent with the pathological features of tenosynovial giant-cell tumor.
RESULTS: A total of 41 patients were enrolled in the dose-escalation study, and an additional 23 patients were enrolled in the extension study. The chosen phase 2 dose of PLX3397 was 1000 mg per day. In the extension study, 12 patients with tenosynovial giant-cell tumors had a partial response and 7 patients had stable disease. Responses usually occurred within the first 4 months of treatment, and the median duration of response exceeded 8 months. The most common adverse events included fatigue, change in hair color, nausea, dysgeusia, and periorbital edema; adverse events rarely led to discontinuation of treatment.
CONCLUSIONS: Treatment of tenosynovial giant-cell tumors with PLX3397 resulted in a prolonged regression in tumor volume in most patients. (Funded by Plexxikon; ClinicalTrials.gov number, NCT01004861.).

Yeung AW, Terentis AC, King NJ, Thomas SR
Role of indoleamine 2,3-dioxygenase in health and disease.
Clin Sci (Lond). 2015; 129(7):601-72 [PubMed] Related Publications
IDO1 (indoleamine 2,3-dioxygenase 1) is a member of a unique class of mammalian haem dioxygenases that catalyse the oxidative catabolism of the least-abundant essential amino acid, L-Trp (L-tryptophan), along the kynurenine pathway. Significant increases in knowledge have been recently gained with respect to understanding the fundamental biochemistry of IDO1 including its catalytic reaction mechanism, the scope of enzyme reactions it catalyses, the biochemical mechanisms controlling IDO1 expression and enzyme activity, and the discovery of enzyme inhibitors. Major advances in understanding the roles of IDO1 in physiology and disease have also been realised. IDO1 is recognised as a prominent immune regulatory enzyme capable of modulating immune cell activation status and phenotype via several molecular mechanisms including enzyme-dependent deprivation of L-Trp and its conversion into the aryl hydrocarbon receptor ligand kynurenine and other bioactive kynurenine pathway metabolites, or non-enzymatic cell signalling actions involving tyrosine phosphorylation of IDO1. Through these different modes of biochemical signalling, IDO1 regulates certain physiological functions (e.g. pregnancy) and modulates the pathogenesis and severity of diverse conditions including chronic inflammation, infectious disease, allergic and autoimmune disorders, transplantation, neuropathology and cancer. In the present review, we detail the current understanding of IDO1's catalytic actions and the biochemical mechanisms regulating IDO1 expression and activity. We also discuss the biological functions of IDO1 with a focus on the enzyme's immune-modulatory function, its medical implications in diverse pathological settings and its utility as a therapeutic target.

Narayanan R
Druggable cancer secretome: neoplasm-associated traits.
Cancer Genomics Proteomics. 2015 May-Jun; 12(3):119-31 [PubMed] Related Publications
BACKGROUND: The genome association databases provide valuable clues to identify novel targets for cancer diagnosis and therapy. Genes harboring phenotype-associated polymorphisms for neoplasm traits can be identified using diverse bioinformatics tools. The recent availability of various protein expression datasets from normal human tissues, including the body fluids, enables for baseline expression profiling of the cancer secretome. Chemoinformatics approaches can help identify drug-like compounds from the protein 3D structures.
MATERIALS AND METHODS: The National Center for Biotechnology Information (NCBI) Phenome Genome Integrator (PheGenI) tool was enriched for neoplasm-associated traits. The neoplasm genes were characterized using diverse bioinformatics tools for pathways, gene ontology, genome-wide association, protein expression and functional class. Chemogenomics analysis was performed using the canSAR protein annotation tool.
RESULTS: The neoplasm-associated traits segregated into 1,305 genes harboring 2,837 single nucleotide polymorphisms (SNPs). Also identified were 65 open reading frames (ORFs) encompassing 137 SNPs. The neoplasm genes and the associated SNPs were classified into distinct tumor types. Protein expression in the secretome was seen for 913 of the neoplasm-associated genes, including 17 novel uncharacterized ORFs. Druggable proteins, including enzymes, transporters, channel proteins and receptors, were detected. Thirty-four novel druggable lead genes emerged from these studies, including seven cancer lead targets. Chemogenomics analysis using the canSAR protein annotation tool identified 168 active compounds (<1 μM) for the neoplasm genes in the body fluids. Among these, 7 most active lead compounds with drug-like properties (1-600 nM) were identified for the cancer lead targets, encompassing enzymes and receptors.
CONCLUSION: Over seventy percent of the neoplasm trait-associated genes were detected in the body fluids, such as ascites, blood, tear, milk, semen, urine, etc. Ligand-based druggabililty analysis helped establish lead prioritization. The association of these proteins with diverse cancer types and other diseases provides a framework to develop novel diagnosis and therapy targets.

Narayanan R
Phenome-genome association studies of pancreatic cancer: new targets for therapy and diagnosis.
Cancer Genomics Proteomics. 2015 Jan-Feb; 12(1):9-19 [PubMed] Related Publications
BACKGROUND: Pancreatic cancer, has a very high mortality rate and requires novel molecular targets for diagnosis and therapy. Genetic association studies over databases offer an attractive starting point for gene discovery.
MATERIALS AND METHODS: The National Center for Biotechnology Information (NCBI) Phenome Genome Integrator (PheGenI) tool was enriched for pancreatic cancer-associated traits. The genes associated with the trait were characterized using diverse bioinformatics tools for Genome-Wide Association (GWA), transcriptome and proteome profile and protein classes for motif and domain.
RESULTS: Two hundred twenty-six genes were identified that had a genetic association with pancreatic cancer in the human genome. This included 25 uncharacterized open reading frames (ORFs). Bioinformatics analysis of these ORFs identified putative druggable proteins and biomarkers including enzymes, transporters and G-protein-coupled receptor signaling proteins. Secreted proteins including a neuroendocrine factor and a chemokine were identified. Five out of these ORFs encompassed non coding RNAs. The ORF protein expression was detected in numerous body fluids, such as ascites, bile, pancreatic juice, milk, plasma, serum and saliva. Transcriptome and proteome analyses showed a correlation of mRNA and protein expression for nine ORFs. Analysis of the Catalogue of Somatic Mutations in Cancer (COSMIC) database revealed a strong correlation across copy number variations and mRNA over-expression for four ORFs. Mining of the International Cancer Gene Consortium (ICGC) database identified somatic mutations in a significant number of pancreatic patients' tumors for most of these ORFs. The pancreatic cancer-associated ORFs were also found to be genetically associated with other neoplasms, including leukemia, malignant melanoma, neuroblastoma and prostate carcinomas, as well as other unrelated diseases and disorders, such as Alzheimer's disease, Crohn's disease, coronary diseases, attention deficit disorder and addiction.
CONCLUSION: Based on Genome-Wide Association Studies (GWAS), copy number variations, somatic mutational status and correlation of gene expression in pancreatic tumors at the mRNA and protein level, expression specificity in normal tissues and detection in body fluids, six ORFs emerged as putative leads for pancreatic cancer. These six targets provide a basis for accelerated drug discovery and diagnostic marker development for pancreatic cancer.

Barón AE, Asdigian NL, Gonzalez V, et al.
Interactions between ultraviolet light and MC1R and OCA2 variants are determinants of childhood nevus and freckle phenotypes.
Cancer Epidemiol Biomarkers Prev. 2014; 23(12):2829-39 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Melanocytic nevi (moles) and freckles are well known biomarkers of melanoma risk, and they are influenced by similar UV light exposures and genetic susceptibilities to those that increase melanoma risk. Nevertheless, the selective interactions between UV exposures and nevus and freckling genes remain largely undescribed.
METHODS: We conducted a longitudinal study from ages 6 through 10 years in 477 Colorado children who had annual information collected for sun exposure, sun protection behaviors, and full body skin exams. MC1R and HERC2/OCA2 rs12913832 were genotyped and linear mixed models were used to identify main and interaction effects.
RESULTS: All measures of sun exposure (chronic, sunburns, and waterside vacations) contributed to total nevus counts, and cumulative chronic exposure acted as the major driver of nevus development. Waterside vacations strongly increased total nevus counts in children with rs12913832 blue eye color alleles and facial freckling scores in those with MC1R red hair color variants. Sunburns increased the numbers of larger nevi (≥2 mm) in subjects with certain MC1R and rs12913832 genotypes.
CONCLUSIONS: Complex interactions between different UV exposure profiles and genotype combinations determine nevus numbers and size, and the degree of facial freckling.
IMPACT: Our findings emphasize the importance of implementing sun-protective behavior in childhood regardless of genetic make-up, although children with particular genetic variants may benefit from specifically targeted preventive measures to counteract their inherent risk of melanoma. Moreover, we demonstrate, for the first time, that longitudinal studies are a highly powered tool to uncover new gene-environment interactions that increase cancer risk.

Manning CS, Hooper S, Sahai EA
Intravital imaging of SRF and Notch signalling identifies a key role for EZH2 in invasive melanoma cells.
Oncogene. 2015; 34(33):4320-32 [PubMed] Free Access to Full Article Related Publications
The acquisition of cell motility is an early step in melanoma metastasis. Here we use intravital imaging of signalling reporter cell-lines combined with genome-wide transcriptional analysis to define signalling pathways and genes associated with melanoma metastasis. Intravital imaging revealed heterogeneous cell behaviour in vivo: <10% of cells were motile and both singly moving cells and streams of cells were observed. Motile melanoma cells had increased Notch- and SRF-dependent transcription. Subsequent genome-wide analysis identified an overlapping set of genes associated with high Notch and SRF activity. We identified EZH2, a histone methyltransferase in the Polycomb repressive complex 2, as a regulator of these genes. Heterogeneity of EZH2 levels is observed in melanoma models, and co-ordinated upregulation of genes positively regulated by EZH2 is associated with melanoma metastasis. EZH2 was also identified as regulating the amelanotic phenotype of motile cells in vivo by suppressing expression of the P-glycoprotein Oca2. Analysis of patient samples confirmed an inverse relationship between EZH2 levels and pigment. EZH2 targeting with siRNA and chemical inhibition reduced invasion in mouse and human melanoma cell lines. The EZH2-regulated genes KIF2C and KIF22 are required for melanoma cell invasion and important for lung colonization. We propose that heterogeneity in EZH2 levels leads to heterogeneous expression of a cohort of genes associated with motile behaviour including KIF2C and KIF22. EZH2-dependent increased expression of these genes promotes melanoma cell motility and early steps in metastasis.

Binstock M, Hafeez F, Metchnikoff C, Arron ST
Single-nucleotide polymorphisms in pigment genes and nonmelanoma skin cancer predisposition: a systematic review.
Br J Dermatol. 2014; 171(4):713-21 [PubMed] Related Publications
Nonmelanoma skin cancer (NMSC) is the most common cancer in the U.S.A. The two most common NMSCs are basal cell carcinoma and squamous cell carcinoma. The associations of single-nucleotide polymorphisms (SNPs) in pigmentation pathway genes with NMSC are not well characterized. There is a series of epidemiological studies that have tested these relationships, but there is no recent summary of these findings. To explain overarching trends, we undertook a systematic review of published studies. The summarized data support the concept that specific SNPs in the pigmentation pathway are of importance for the pathogenesis of NMSC. The SNPs with the most promising evidence include MC1R rs1805007(T) (Arg151Cys) and rs1805008(T) (Arg160Trp), and ASIP AH haplotype [rs4911414(T) and rs1015362(G)]. There are a few other SNPs found in TYR, OCA2 and SLC45A2 that may show additional correlation after future research. With additional research there is potential for the translation of future findings to the clinic in the form of SNP screenings, where patients at high risk for NMSC can be identified beyond their phenotype by genotypically screening for predisposing SNPs.

Delgado AP, Brandao P, Chapado MJ, et al.
Open reading frames associated with cancer in the dark matter of the human genome.
Cancer Genomics Proteomics. 2014 Jul-Aug; 11(4):201-13 [PubMed] Related Publications
BACKGROUND: The uncharacterized proteins (open reading frames, ORFs) in the human genome offer an opportunity to discover novel targets for cancer. A systematic analysis of the dark matter of the human proteome for druggability and biomarker discovery is crucial to mining the genome. Numerous data mining tools are available to mine these ORFs to develop a comprehensive knowledge base for future target discovery and validation.
MATERIALS AND METHODS: Using the Genetic Association Database, the ORFs of the human dark matter proteome were screened for evidence of association with neoplasms. The Phenome-Genome Integrator tool was used to establish phenotypic association with disease traits including cancer. Batch analysis of the tools for protein expression analysis, gene ontology and motifs and domains was used to characterize the ORFs.
RESULTS: Sixty-two ORFs were identified for neoplasm association. The expression Quantitative Trait Loci (eQTL) analysis identified thirteen ORFs related to cancer traits. Protein expression, motifs and domain analysis and genome-wide association studies verified the relevance of these OncoORFs in diverse tumors. The OncoORFs are also associated with a wide variety of human diseases and disorders.
CONCLUSIONS: Our results link the OncoORFs to diverse diseases and disorders. This suggests a complex landscape of the uncharacterized proteome in human diseases. These results open the dark matter of the proteome to novel cancer target research.

Kosiniak-Kamysz A, Marczakiewicz-Lustig A, Marcińska M, et al.
Increased risk of developing cutaneous malignant melanoma is associated with variation in pigmentation genes and VDR, and may involve epistatic effects.
Melanoma Res. 2014; 24(4):388-96 [PubMed] Related Publications
Cutaneous malignant melanoma (CMM) is a malicious human skin cancer that primarily affects individuals with light pigmentation and heavy sun exposure, but also has a known familial association. Multiple genes and polymorphisms have been reported as low-penetrance susceptibility loci for CMM. Here, we examined 33 candidate polymorphisms located in 11 pigmentation genes and the vitamin D receptor gene (VDR) in a population of 130 cutaneous melanoma patients and 707 healthy controls. The genotypes obtained were evaluated for main association effects and potential gene-gene interactions. MC1R, TYR, VDR and SLC45A2 genes were found to be associated with CMM in our population. The results obtained for major function MC1R mutations were the most significant [with odds ratio (OR)=1.787, confidence interval (CI)=1.320-2.419 and P=1.715(-4)], followed by TYR (rs1393350) (with OR=1.569, CI=1.162-2.118, P=0.003), VDR (GCCC haplotype in rs2238136-rs4516035-rs7139166-rs11568820 block) (with OR=5.653, CI=1.794-17.811, P=0.003) and SLC45A2 (rs16891982) (with OR=0.238, CI=0.057-0.987, P=0.048). The study also detected significant intermolecular epistatic effects between MC1R and TYR, SLC45A2 and VDR, HERC2 and VDR, OCA2 and TPCN2, as well as intramolecular interactions between variants within the genes MC1R and VDR. In the final multivariate logistic regression model for CMM development, only the gene-gene interactions discovered remained significant, showing that epistasis may be an important factor in the risk of melanoma.

Delgado AP, Hamid S, Brandao P, Narayanan R
A novel transmembrane glycoprotein cancer biomarker present in the X chromosome.
Cancer Genomics Proteomics. 2014 Mar-Apr; 11(2):81-92 [PubMed] Related Publications
BACKGROUND: The uncharacterized proteins of the human proteome offer an untapped potential for cancer biomarker discovery. Numerous predicted open reading frames (ORFs) are present in diverse chromosomes. The mRNA and protein expression data, as well as the mutational and variant information for these ORF proteins are available in the cancer-related bioinformatics databases.
MATERIALS AND METHODS: ORF proteins were mined using bioinformatics and proteomic tools to predict motifs and domains, and cancer relevance was established using cancer genome, transcriptome and proteome analysis tools.
RESULTS: A novel testis-restricted ORF protein present in chromosome X called CXorf66 was detected in the serum, plasma and neutrophils. This gene is termed secreted glycoprotein in chromosome X (SGPX). The SGPX gene is up-regulated in cancer of the brain, lung and in leukemia, and down-regulated in liver and prostate cancer. Brain cancer in female patients exhibited elevated copy numbers of the SGPX gene.
CONCLUSION: The SGPX gene is a putative novel cancer biomarker. Our results demonstrate the feasibility of mining the 'dark matter' of the cancer proteome for rapid cancer biomarker discovery.

Yoshizawa J, Abe Y, Oiso N, et al.
Variants in melanogenesis-related genes associate with skin cancer risk among Japanese populations.
J Dermatol. 2014; 41(4):296-302 [PubMed] Related Publications
Human skin color is known to be associated with the risk of cutaneous cancer. Some reports indicated that pigmentation-related gene variants were associated with cutaneous cancer risk in Caucasian populations, but there are no similar reports in East Asian populations. This study aimed to evaluate the association between pigmentation-related genes and the risk of skin cancer in Japanese populations. We studied the associations between 12 variants of four pigmentation-related genes and melanin index variations in 198 Japanese patients with skin cancer and compared these findings to those of 500 Japanese controls by using multiple logistic regression analysis. Furthermore, we analyzed an independent sample of 107 Japanese patients with skin cancer. A non-synonymous variant, H615R in the oculocutaneous albinism 2 gene (OCA2), was associated with the risk of malignant melanoma in the Yamagata group (odds ratio [OR], 0.38; 95% confidence interval [CI], 0.17-0.86; P = 0.020). Another non-synonymous variant, A481T in OCA2, was associated with the risk of squamous cell carcinoma and actinic keratosis in the Osaka group (OR, 3.16; 95% CI, 1.41-7.04; P = 0.005). In malignant melanoma cases, the minor allele in OCA2 H615R might have induced the development of lesions in sun-exposed skin (OR, 26.32; 95% CI, 1.96-333; P = 0.014). Our results suggest that some OCA2 variants are definite risk factors for the onset of cutaneous cancer in Japanese populations.

Jaramillo-Rodríguez Y, Cerda-Flores RM, Ruiz-Ramos R, et al.
YAP expression in normal and neoplastic breast tissue: an immunohistochemical study.
Arch Med Res. 2014; 45(3):223-8 [PubMed] Related Publications
BACKGROUND AND AIMS: Yes-associated protein (YAP) is a transcriptional factor involved in normal cell proliferation, apoptosis and carcinogenesis; however, its contribution to breast cancer (BC) is still controversial. We undertook this study to compare the expression of YAP by immunohistochemistry (IHC) in normal breast tissue of women without breast cancer (BC) (controls), non-neoplastic breast tissue in women with cancer (internal controls) and in four different subtypes of invasive ductal carcinoma.
METHODS: There were 17 controls and 105 tumor cases (53 luminal A, 15 luminal B, 20 overexpression of HER2 and 17 triple negative cases) studied by IHC. Statistical analysis included χ(2) for linear trend (Extended Mantel-Haenszel).
RESULTS: There were 40% of internal controls that showed expression of YAP in myoepithelial cells, whereas in controls expression was 100%. In controls, 3/17 (17.6%) showed cytoplasmic staining in luminal cells. There was a significant difference in nuclear expression between the ductal BC subtypes. Luminal A had 4% of positive cases with <10% of cells affected in each case; in contrast, there were 17-20% of positive cases in the other groups with 50% or more of stained cells. YAP expression in stromal cells was not observed in controls or in triple-negative cases, and luminal B pattern had the highest YAP nuclear expression (20%).
CONCLUSIONS: YAP showed decreased expression in tumor cells compared with normal breast tissue. These findings are consistent with a role of YAP as a suppressor gene in BC and show differences in YAP expression in different patterns of ductal BC.

Parmigiani G, Boca S, Ding J, Trippa L
Statistical tools and R software for cancer driver probabilities.
Methods Mol Biol. 2014; 1101:113-34 [PubMed] Related Publications
This chapter provides a description and illustration of CancerMutationAnalysis and Cancer MutationMCMC, two open source R packages specifically designed for the analysis of somatic mutations in cancer genome studies, at both the gene and gene-set levels.

Boca SM, Sinha R, Cross AJ, et al.
Testing multiple biological mediators simultaneously.
Bioinformatics. 2014; 30(2):214-20 [PubMed] Free Access to Full Article Related Publications
MOTIVATION: Modern biomedical and epidemiological studies often measure hundreds or thousands of biomarkers, such as gene expression or metabolite levels. Although there is an extensive statistical literature on adjusting for 'multiple comparisons' when testing whether these biomarkers are directly associated with a disease, testing whether they are biological mediators between a known risk factor and a disease requires a more complex null hypothesis, thus offering additional methodological challenges.
RESULTS: We propose a permutation approach that tests multiple putative mediators and controls the family wise error rate. We demonstrate that, unlike when testing direct associations, replacing the Bonferroni correction with a permutation approach that focuses on the maximum of the test statistics can significantly improve the power to detect mediators even when all biomarkers are independent. Through simulations, we show the power of our method is 2-5× larger than the power achieved by Bonferroni correction. Finally, we apply our permutation test to a case-control study of dietary risk factors and colorectal adenoma to show that, of 149 test metabolites, docosahexaenoate is a possible mediator between fish consumption and decreased colorectal adenoma risk.
AVAILABILITY AND IMPLEMENTATION: R-package included in online Supplementary Material.

Falkenius J, Lundeberg J, Johansson H, et al.
High expression of glycolytic and pigment proteins is associated with worse clinical outcome in stage III melanoma.
Melanoma Res. 2013; 23(6):452-60 [PubMed] Related Publications
There are insufficient numbers of prognostic factors available for prediction of clinical outcome in patients with stage III malignant cutaneous melanoma, even when known adverse pathological risk factors, such as macrometastasis, number of lymph node metastases, and ulceration are taken into consideration. The aim of this study was therefore to identify additional prognostic factors to better predict patients with a high risk of relapse, thus enabling us to better determine the need for adjuvant treatment in stage III disease. An RNA oligonucleotide microarray study was performed on first regional lymph node metastases in 42 patients with stage III melanoma: 23 patients with short-term survival (≤ 13 months) and 19 with long-term survival (≥ 60 months), to identify genes associated with clinical outcome. Candidate genes were validated by real-time PCR and immunohistochemical analysis. Several gene ontology (GO) categories were highly significantly differentially expressed including glycolysis (GO: 0006096; P<0.001) and the pigment biosynthetic process (GO: 0046148; P<0.001), in which overexpression was associated with short-disease-specific survival. Three overexpressed glycolytic genes, GAPDHS, GAPDH, and PKM2, and two pigment-related genes, TYRP1 and OCA2, were selected for validation. A significant difference in GAPDHS protein expression between short- and long-term survivors (P=0.021) and a trend for PKM2 (P=0.093) was observed in univariate analysis. Positive expression of at least two of four proteins (GAPDHS, GAPDH, PKM2, TYRP1) in immunohistochemical analysis was found to be an independent adverse prognostic factor for disease-specific survival (P=0.011). Our results indicate that this prognostic panel in combination with established risk factors may contribute to an improved prediction of patients with a high risk of relapse.

Zhang M, Song F, Liang L, et al.
Genome-wide association studies identify several new loci associated with pigmentation traits and skin cancer risk in European Americans.
Hum Mol Genet. 2013; 22(14):2948-59 [PubMed] Free Access to Full Article Related Publications
Aiming to identify novel genetic loci for pigmentation and skin cancer, we conducted a series of genome-wide association studies on hair color, eye color, number of sunburns, tanning ability and number of non-melanoma skin cancers (NMSCs) among 10 183 European Americans in the discovery stage and 4504 European Americans in the replication stage (for eye color, 3871 males in the discovery stage and 2496 males in the replication stage). We targeted novel chromosome regions besides the known ones for replication. As a result, we identified a new region downstream of the EDNRB gene on 13q22 associated with hair color and the strongest association was the single-nucleotide polymorphism (SNP) rs975739 (P = 2.4 × 10(-14); P = 5.4 × 10(-9) in the discovery set and P = 1.2 × 10(-6) in the replication set). Using blue, intermediate (including green) and brown eye colors as co-dominant outcomes, we identified the SNP rs3002288 in VASH2 on 1q32.3 associated with brown eye (P = 7.0 × 10(-8); P = 5.3 × 10(-5) in the discovery set and P = 0.02 in the replication set). Additionally, we identified a significant interaction between the SNPs rs7173419 and rs12913832 in the OCA2 gene region on brown eye color (P-value for interaction = 3.8 × 10(-3)). As for the number of NMSCs, we identified two independent SNPs on chr6 and one SNP on chromosome 14: rs12203592 in IRF4 (P = 7.2 × 10(-14); P = 1.8 × 10(-8) in the discovery set and P = 6.7 × 10(-7) in the replication set), rs12202284 between IRF4 and EXOC2 (P = 5.0 × 10(-8); P = 6.6 × 10(-7) in the discovery set and P = 3.0 × 10(-3) in the replication set) and rs8015138 upstream of GNG2 (P = 6.6 × 10(-8); P = 5.3 × 10(-7) in the discovery set and P = 0.01 in the replication set).

Peña-Chilet M, Blanquer-Maceiras M, Ibarrola-Villava M, et al.
Genetic variants in PARP1 (rs3219090) and IRF4 (rs12203592) genes associated with melanoma susceptibility in a Spanish population.
BMC Cancer. 2013; 13:160 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Few high penetrance genes are known in Malignant Melanoma (MM), however, the involvement of low-penetrance genes such as MC1R, OCA2, ASIP, SLC45A2 and TYR has been observed. Lately, genome-wide association studies (GWAS) have been the ideal strategy to identify new common, low-penetrance susceptibility loci. In this case-control study, we try to validate in our population nine melanoma associated markers selected from published GWAS in melanoma predisposition.
METHODS: We genotyped the 9 markers corresponding to 8 genes (PARP1, MX2, ATM, CCND1, NADSYN1, CASP8, IRF4 and CYP2R1) in 566 cases and 347 controls from a Spanish population using KASPar probes. Genotypes were analyzed by logistic regression and adjusted by phenotypic characteristics.
RESULTS: We confirm the protective role in MM of the rs3219090 located on the PARP1 gene (p-value 0.027). Additionally, this SNP was also associated with eye color (p-value 0.002). A second polymorphism, rs12203592, located on the IRF4 gene was associated with protection to develop MM for the dominant model (p-value 0.037). We have also observed an association of this SNP with both lentigines (p-value 0.014) and light eye color (p-value 3.76 × 10(-4)). Furthermore, we detected a novel association with rs1485993, located on the CCND1 gene, and dark eye color (p-value 4.96 × 10(-4)). Finally, rs1801516, located on the ATM gene, showed a trend towards a protective role in MM similar to the one firstly described in a GWAS study.
CONCLUSIONS: To our knowledge, this is the first time that these SNPs have been associated with MM in a Spanish population. We confirmed the proposed role of rs3219090, located on the PARP1 gene, and rs12203592, located on the IRF4 gene, as protective to MM along the same lines as have previous genome-wide associated works. Finally, we have seen associations between IRF4, PARP1, and CCND1 and phenotypic characteristics, confirming previous results for the IRF4 gene and presenting novel data for the last two, suggesting that pigmentation characteristics correlated with eye color are potential mediators between PARP1 and MM protection.

Liu H, Lu M, Guthrie KM
Anterograde trafficking of neurotrophin-3 in the adult olfactory system in vivo.
Exp Neurol. 2013; 241:125-37 [PubMed] Free Access to Full Article Related Publications
The olfactory system continuously incorporates new neurons into functional circuits throughout life. Axons from olfactory sensory neurons (OSNs) in the nasal cavity synapse on mitral, tufted and periglomerular (PG) cells in the main olfactory bulb, and low levels of turnover within the OSN population results in ingrowth of new axons under normal physiological conditions. Subpopulations of bulb interneurons are continually eliminated by apoptosis, and are replaced by new neurons derived from progenitors in the adult forebrain subventricular zone. Integration of new neurons, including PG cells that are contacted by sensory axons, leads to ongoing reorganization of adult olfactory bulb circuits. The mechanisms regulating this adaptive structural plasticity are not all known, but the process is reminiscent of early nervous system development. Neurotrophic factors have well-established roles in controlling neuronal survival and connectivity during development, leading to speculation that trophic interactions between OSNs and their target bulb neurons may mediate some of these same processes in adults. A number of different trophic factors and their cognate receptors are expressed in the adult olfactory pathway. Neurotrophin-3 (NT3) is among these, as reflected by beta-galactosidase expression in transgenic reporter mice expressing lacZ under the NT3 promoter. Using a combination of approaches, including immunocytochemistry, real-time PCR of laser-captured RNA, and adenovirus-mediated gene transfer of NT3 fusion peptides in vivo, we demonstrate that OSNs express and anterogradely transport NT3 to the olfactory bulb. We additionally observe that in mice treated with adenovirus encoding NT3 tagged with hemagglutinin (HA), a subset of bulb neurons expressing the TrkC neurotrophin receptor are immunoreactive for HA, suggesting their acquisition of the fusion peptide from infected sensory neurons. Our results therefore provide evidence that OSNs may serve as an afferent source of trophic signals for the adult mouse olfactory bulb.

Hawkes JE, Cassidy PB, Manga P, et al.
Report of a novel OCA2 gene mutation and an investigation of OCA2 variants on melanoma risk in a familial melanoma pedigree.
J Dermatol Sci. 2013; 69(1):30-7 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Oculocutaneous albinism type 2 (OCA2) is caused by mutations of the OCA2 gene. Individuals affected by OCA2 as well as other types of albinism are at a significantly increased risk for sun-induced skin-cancers, including malignant melanoma (MM).
OBJECTIVE: To identify the molecular etiology of oculocutaneous albinism in a previously uncharacterized melanoma pedigree and to investigate the relationship between two OCA2 variants and melanoma predisposition in this pedigree.
METHODS: DNA and RNA were isolated from the peripheral blood of seven patients in a familial melanoma pedigree. Electron microscopy was performed on the individual with clinical oculocutaneous albinism. OCA2, TYRP1, MC1R, CDKN2A/p16, CDKN2A/p19ARF, and CDK4 genes were sequenced in affected individuals. The relationship between OCA2 variants and melanoma was assessed using a pedigree likelihood-based method.
RESULTS: The proband was determined to be an OCA2 compound heterozygous mutation carrier with a previously reported conservative missense mutation (V443I) and a novel non-conservative missense mutation (L734R). The pedigree contained individuals diagnosed with both cutaneous and iris melanoma. Based on co-segregation analysis, the odds of these OCA2 variants being high penetrance loci for melanoma was: 1.3-to-1 if we include the iris melanoma as affected and 6.5-to-1 if we only consider cutaneous melanoma as affected.
CONCLUSION: The discovery of this novel OCA2 variant adds to the body of evidence on the detrimental effects of OCA2 gene mutations on pigmentation, supports existing GWAS data on the relevance of the OCA2 gene in melanoma predisposition, and may ultimately assist in the development of targeted molecular therapies in the treatment of OCA and melanoma.

Amos CI, Wang LE, Lee JE, et al.
Genome-wide association study identifies novel loci predisposing to cutaneous melanoma.
Hum Mol Genet. 2011; 20(24):5012-23 [PubMed] Free Access to Full Article Related Publications
We performed a multistage genome-wide association study of melanoma. In a discovery cohort of 1804 melanoma cases and 1026 controls, we identified loci at chromosomes 15q13.1 (HERC2/OCA2 region) and 16q24.3 (MC1R) regions that reached genome-wide significance within this study and also found strong evidence for genetic effects on susceptibility to melanoma from markers on chromosome 9p21.3 in the p16/ARF region and on chromosome 1q21.3 (ARNT/LASS2/ANXA9 region). The most significant single-nucleotide polymorphisms (SNPs) in the 15q13.1 locus (rs1129038 and rs12913832) lie within a genomic region that has profound effects on eye and skin color; notably, 50% of variability in eye color is associated with variation in the SNP rs12913832. Because eye and skin colors vary across European populations, we further evaluated the associations of the significant SNPs after carefully adjusting for European substructure. We also evaluated the top 10 most significant SNPs by using data from three other genome-wide scans. Additional in silico data provided replication of the findings from the most significant region on chromosome 1q21.3 rs7412746 (P = 6 × 10(-10)). Together, these data identified several candidate genes for additional studies to identify causal variants predisposing to increased risk for developing melanoma.

Han J, Qureshi AA, Nan H, et al.
A germline variant in the interferon regulatory factor 4 gene as a novel skin cancer risk locus.
Cancer Res. 2011; 71(5):1533-9 [PubMed] Free Access to Full Article Related Publications
Genome-wide association studies on pigmentary phenotypes provide a pool of candidate genetic markers for skin cancer risk. The SNPs identified from a genome-wide association study of natural hair color were assessed for associations with the risk of three types of skin cancer simultaneously in a nested case-control study within the Nurses' Health Study [218 melanoma, 285 squamous cell carcinoma (SCC), and 300 basal cell carcinoma (BCC) cases, and 870 common controls]. Along with two known pigmentation loci, MC1R and OCA2, the IRF4 rs12203592 T allele was associated with an increased risk of each type of skin cancer (P value, 6.6 × 10(-4) for melanoma, 7.0 × 10(-7) for SCC, and 0.04 for BCC). This association was further replicated in additional samples (190 melanoma, 252 SCC, and 634 common controls). The P value in the replication set was 0.03 for melanoma and 4.2 × 10(-3) for SCC. The risk of BCC was replicated in an independent set of 213 cases and 718 controls (P value, 0.02). The combined results showed that the association with SCC reached the genome-wide significance level [odds ratio (OR) for additive model = 1.61, 95%CI, 1.36-1.91, P = 3.2 × 10(-8)]. The OR was 1.49 for melanoma (95%CI, 1.23-1.80; P = 4.5 × 10(-5)), and 1.32 for BCC (95%CI, 1.11-1.57; P = 1.6 × 10(-3)). Given that the T allele was shown previously to be associated with increased expression of IRF4 locus, further studies are warranted to elucidate the role of the IRF4 gene in human pigmentation and skin cancer development.

Parsons DW, Li M, Zhang X, et al.
The genetic landscape of the childhood cancer medulloblastoma.
Science. 2011; 331(6016):435-9 [PubMed] Free Access to Full Article Related Publications
Medulloblastoma (MB) is the most common malignant brain tumor of children. To identify the genetic alterations in this tumor type, we searched for copy number alterations using high-density microarrays and sequenced all known protein-coding genes and microRNA genes using Sanger sequencing in a set of 22 MBs. We found that, on average, each tumor had 11 gene alterations, fewer by a factor of 5 to 10 than in the adult solid tumors that have been sequenced to date. In addition to alterations in the Hedgehog and Wnt pathways, our analysis led to the discovery of genes not previously known to be altered in MBs. Most notably, inactivating mutations of the histone-lysine N-methyltransferase genes MLL2 or MLL3 were identified in 16% of MB patients. These results demonstrate key differences between the genetic landscapes of adult and childhood cancers, highlight dysregulation of developmental pathways as an important mechanism underlying MBs, and identify a role for a specific type of histone methylation in human tumorigenesis.

Giricz O, Lauer JL, Fields GB
Variability in melanoma metalloproteinase expression profiling.
J Biomol Tech. 2010; 21(4):194-204 [PubMed] Free Access to Full Article Related Publications
The proteolytic activities of a disintegrin and metalloproteinase (ADAM); a disintegrin and metalloproteinase with thrombospondin motifs (ADAMTS), and matrix metalloproteinase (MMP) families play important roles in normal and multiple pathological conditions. These metalloproteases have potential roles in the degradation of the ECM and in the processing of bioactive molecules. In the present study, RNA was isolated from multiple normal fibroblast and metastatic melanoma cell lines, as well as the isogenic normal tissue and tumor samples, and the gene expression levels of six ADAMs, eight MMPs, and four ADAMTSs were analyzed by real-time PCR. This approach allowed for detected changes in mRNA expression of the individual metalloproteinase genes to be compared between normal and metastatic states and also between tissue and cultured cells. Increased gene expression of several ADAM and MMP family members (MMP1, MMP8, MMP15, and ADAM15) occurred in melanoma tissue and was replicated in tissue cultures. In general, the level of ADAM and MMP mRNA expression was several-fold higher in cultured cells compared with the isogenic tissue from which they were derived. Passage-dependent expression patterns were observed for MMP8 and MMP9 in in-house-derived metastatic melanoma cell lines. This reiterates earlier suggestions that experiments using cells that have been maintained in culture should be interpreted with great care.

Boca SM, Kinzler KW, Velculescu VE, et al.
Patient-oriented gene set analysis for cancer mutation data.
Genome Biol. 2010; 11(11):R112 [PubMed] Free Access to Full Article Related Publications
Recent research has revealed complex heterogeneous genomic landscapes in human cancers. However, mutations tend to occur within a core group of pathways and biological processes that can be grouped into gene sets. To better understand the significance of these pathways, we have developed an approach that initially scores each gene set at the patient rather than the gene level. In mutation analysis, these patient-oriented methods are more transparent, interpretable, and statistically powerful than traditional gene-oriented methods.

Ibarrola-Villava M, Fernandez LP, Pita G, et al.
Genetic analysis of three important genes in pigmentation and melanoma susceptibility: CDKN2A, MC1R and HERC2/OCA2.
Exp Dermatol. 2010; 19(9):836-44 [PubMed] Related Publications
The CDKN2A gene is regarded as the major familial malignant melanoma (MM) susceptibility gene. Human pigmentation is one of the main modulators of individual risk of developing MM. Therefore, the genes involved in the determination of skin colour and tanning response are potentially implicated in MM predisposition and may be useful predictors of MM risk in the general population. The human melanocortin-1 receptor gene (MC1R) plays a crucial role in pigmentation and also appears to be important in MM. The OCA2 gene has emerged as a new and significant determinant of human iris colour variation. We present a case-control study in Spanish population including 390 consecutive patients with melanoma and 254 control subjects. Sequence analysis of the entire coding region and genotyping of 5 tag-SNPs in the genomic region of MC1R was performed. We identified 27 variants, two reaching statistical significance [R160W (OR: 4.18, 95% CI: 1.24-14.04, P = 0.02) and D294H (OR: 3.10, 95% CI: 1.37-7.01, P = 0.01)] and we detected two novel non-synonymous changes: V92L and T308M. Odds ratio for carrying two functional variants was 4.25 (95% CI: 2.30-7.84, P = 3.63 x 10(-6)). Haplotypes of the entire MC1R region have been established, and we observed an enrichment of a rare European haplotype similar to African values carrying variants V92M and I155T. In addition, three potentially functional SNPs were selected in p16/CDKN2A and in the promoter region of OCA2/HERC2. Our data for CDKN2A gene did not reach statistically significant results for any of the two studied alleles. We found that the variant allele A > G of OCA2/HERC2 (rs12913832) was associated with pigmentation features: eye, hair and skin colour; P-values = 1.8 x 10(-29), 9.2 x 10(-16), 1.1 x 10(-3), respectively, validating previous results.

Scherer D, Kumar R
Genetics of pigmentation in skin cancer--a review.
Mutat Res. 2010; 705(2):141-53 [PubMed] Related Publications
Skin pigmentation is one of the most overt human physical traits with consequences on susceptibility to skin cancer. The variations in skin pigmentation are dependent on geographic location and population ethnicity. Skin colouration is mainly due to the pigmentation substance melanin, produced in specialized organelles (melanosomes) within dendritic melanocytes, and transferred to neighbouring keratinocytes. The two types of melanin synthesized in well defined chemical reactions are the protective dark coloured eumelanin and the sulphur containing light red-yellow pheomelanin. The events leading to the synthesis of melanin are controlled by signalling cascades that involve a host of genes encoding ligands, receptors, transcription factors, channel transporters and many other crucial molecules. Several variants within the genes involved in pigmentation have been associated with high risk phenotypes like fair skin, brown-red hair and green-blue eyes. Many of those variants have also been implicated in the risk of various skin cancers. The variants within the key pigmentation gene, melanocortin-receptor 1 (MC1R), in particular have been ubiquitously linked with high risk traits and skin cancers involving both pigmentary and non-pigmentary functions and likely interaction with variants in other genes. Many of the variants in other genes, functional in pigmentation pathway, have also been associated with phenotypic variation and risk of skin cancers. Those genes include agouti signalling protein (ASIP), tyrosinase (TYR), tyrosinase-related protein 1 (TYRP1), oculocutaneous albinism II (OCA2), various solute carrier genes and transporters. Most of those associations have been confirmed in genome wide association studies that at the same time have also identified new loci involved in phenotypic variation and skin cancer risk. In conclusion, the genetic variants within the genes involved in skin pigmentation besides influencing phenotypic traits are important determinants of risk of several skin cancers. However, ultimate risk of skin cancer is dependent on interplay between genetic and host factors.

Azzato EM, Tyrer J, Fasching PA, et al.
Association between a germline OCA2 polymorphism at chromosome 15q13.1 and estrogen receptor-negative breast cancer survival.
J Natl Cancer Inst. 2010; 102(9):650-62 [PubMed] Free Access to Full Article Related Publications
BACKGROUND: Traditional prognostic factors for survival and treatment response of patients with breast cancer do not fully account for observed survival variation. We used available genotype data from a previously conducted two-stage, breast cancer susceptibility genome-wide association study (ie, Studies of Epidemiology and Risk factors in Cancer Heredity [SEARCH]) to investigate associations between variation in germline DNA and overall survival.
METHODS: We evaluated possible associations between overall survival after a breast cancer diagnosis and 10 621 germline single-nucleotide polymorphisms (SNPs) from up to 3761 patients with invasive breast cancer (including 647 deaths and 26 978 person-years at risk) that were genotyped previously in the SEARCH study with high-density oligonucleotide microarrays (ie, hypothesis-generating set). Associations with all-cause mortality were assessed for each SNP by use of Cox regression analysis, generating a per rare allele hazard ratio (HR). To validate putative associations, we used patient genotype information that had been obtained with 5' nuclease assay or mass spectrometry and overall survival information for up to 14 096 patients with invasive breast cancer (including 2303 deaths and 70 019 person-years at risk) from 15 international case-control studies (ie, validation set). Fixed-effects meta-analysis was used to generate an overall effect estimate in the validation dataset and in combined SEARCH and validation datasets. All statistical tests were two-sided.
RESULTS: In the hypothesis-generating dataset, SNP rs4778137 (C>G) of the OCA2 gene at 15q13.1 was statistically significantly associated with overall survival among patients with estrogen receptor-negative tumors, with the rare G allele being associated with increased overall survival (HR of death per rare allele carried = 0.56, 95% confidence interval [CI] = 0.41 to 0.75, P = 9.2 x 10(-5)). This association was also observed in the validation dataset (HR of death per rare allele carried = 0.88, 95% CI = 0.78 to 0.99, P = .03) and in the combined dataset (HR of death per rare allele carried = 0.82, 95% CI = 0.73 to 0.92, P = 5 x 10(-4)).
CONCLUSION: The rare G allele of the OCA2 polymorphism, rs4778137, may be associated with improved overall survival among patients with estrogen receptor-negative breast cancer.

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