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1.
Int J Cancer ; 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33423300

RESUMO

A 30-kb deletion that eliminates the coding region of APOBEC3B (A3B) is >5 times more common in women of Asian compared to European descent. This polymorphism creates a chimera with the APOBEC3A (A3A) coding region and A3B 3'UTR, and is associated with an increased risk for breast cancer in Asian women. Here, we explored the relationship between the A3B deletion polymorphism with tumour characteristics in Asian women. Using whole exome and whole transcriptome sequencing data of 527 breast tumours, we report that germline A3B deletion polymorphism leads to expression of the A3A-B hybrid isoform and increased APOBEC-associated somatic hypermutation. Hypermutated tumours, regardless of A3B germline status, were associated with the Her2 molecular subtype and PIK3CA mutations. Compared to non-hypermutated tumours, hypermutated tumours also had higher neoantigen burden, tumour heterogeneity and immune activation. Taken together, our results suggest that the germline A3B deletion polymorphism, via the A3A-B hybrid isoform, contributes to APOBEC-mutagenesis in a significant proportion of Asian breast cancers. In addition, APOBEC somatic hypermutation, regardless of A3B background, may be an important clinical biomarker for Asian breast cancers. This article is protected by copyright. All rights reserved.

2.
Nat Commun ; 11(1): 6433, 2020 12 22.
Artigo em Inglês | MEDLINE | ID: mdl-33353943

RESUMO

Molecular profiling of breast cancer has enabled the development of more robust molecular prognostic signatures and therapeutic options for breast cancer patients. However, non-Caucasian populations remain understudied. Here, we present the mutational, transcriptional, and copy number profiles of 560 Malaysian breast tumours and a comparative analysis of breast cancers arising in Asian and Caucasian women. Compared to breast tumours in Caucasian women, we show an increased prevalence of HER2-enriched molecular subtypes and higher prevalence of TP53 somatic mutations in ER+ Asian breast tumours. We also observe elevated immune scores in Asian breast tumours, suggesting potential clinical response to immune checkpoint inhibitors. Whilst HER2-subtype and enriched immune score are associated with improved survival, presence of TP53 somatic mutations is associated with poorer survival in ER+ tumours. Taken together, these population differences unveil opportunities to improve the understanding of this disease and lay the foundation for precision medicine in different populations.


Assuntos
Grupo com Ancestrais do Continente Asiático/genética , Neoplasias da Mama/genética , Genética Populacional , Neoplasias da Mama/imunologia , Neoplasias da Mama/patologia , Grupo com Ancestrais do Continente Europeu/genética , Feminino , Genoma Humano , Humanos , Mutação/genética , Receptor ErbB-2/genética , Receptor ErbB-2/metabolismo , Receptores Estrogênicos/metabolismo , Análise de Sobrevida , Microambiente Tumoral/imunologia , Proteína Supressora de Tumor p53/genética
3.
Nat Commun ; 11(1): 3833, 2020 07 31.
Artigo em Inglês | MEDLINE | ID: mdl-32737321

RESUMO

Polygenic risk scores (PRS) have been shown to predict breast cancer risk in European women, but their utility in Asian women is unclear. Here we evaluate the best performing PRSs for European-ancestry women using data from 17,262 breast cancer cases and 17,695 controls of Asian ancestry from 13 case-control studies, and 10,255 Chinese women from a prospective cohort (413 incident breast cancers). Compared to women in the middle quintile of the risk distribution, women in the highest 1% of PRS distribution have a ~2.7-fold risk and women in the lowest 1% of PRS distribution has ~0.4-fold risk of developing breast cancer. There is no evidence of heterogeneity in PRS performance in Chinese, Malay and Indian women. A PRS developed for European-ancestry women is also predictive of breast cancer risk in Asian women and can help in developing risk-stratified screening programmes in Asia.


Assuntos
Neoplasias da Mama/diagnóstico , Neoplasias da Mama/genética , Herança Multifatorial , Polimorfismo de Nucleotídeo Único , Adulto , Idoso , Ásia/epidemiologia , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/etnologia , Estudos de Casos e Controles , Europa (Continente)/epidemiologia , Feminino , Predisposição Genética para Doença , Estudo de Associação Genômica Ampla , Humanos , Pessoa de Meia-Idade , Razão de Chances , Prognóstico , Risco
4.
PLoS One ; 13(9): e0203469, 2018.
Artigo em Inglês | MEDLINE | ID: mdl-30216346

RESUMO

BACKGROUND: Breast cancer risk factors have been examined extensively in Western setting and more developed Asian cities/countries. However, there are limited data on developing Asian countries. The purpose of this study was to examine breast cancer risk factors and the change of selected risk factors across birth cohorts in Malaysian women. METHODS: An unmatched hospital based case-control study was conducted from October 2002 to December 2016 in Selangor, Malaysia. A total of 3,683 cases and 3,980 controls were included in this study. Unconditional logistic regressions, adjusted for potential confounding factors, were conducted. The breast cancer risk factors were compared across four birth cohorts by ethnicity. RESULTS: Ever breastfed, longer breastfeeding duration, a higher soymilk and soy product intake, and a higher level of physical activity were associated with lower risk of breast cancer. Chinese had the lowest breastfeeding rate, shortest breastfeeding duration, lowest parity and highest age of first full term pregnancy. CONCLUSIONS: Our study shows that breastfeeding, soy intake and physical activity are modifiable risk factors for breast cancer. With the increasing incidence of breast cancer there is an urgent need to educate the women about lifestyle intervention they can take to reduce their breast cancer risk.


Assuntos
Neoplasias da Mama/epidemiologia , Adulto , Idoso , Aleitamento Materno , Estudos de Casos e Controles , Feminino , Humanos , Malásia/epidemiologia , Pessoa de Meia-Idade , Fatores de Risco , Proteínas de Soja/efeitos adversos
5.
J Med Genet ; 55(2): 97-103, 2018 02.
Artigo em Inglês | MEDLINE | ID: mdl-28993434

RESUMO

BACKGROUND: Genetic testing for BRCA1 and BRCA2 is offered typically to selected women based on age of onset and family history of cancer. However, current internationally accepted genetic testing referral guidelines are built mostly on data from cancer genetics clinics in women of European descent. To evaluate the appropriateness of such guidelines in Asians, we have determined the prevalence of germ line variants in an unselected cohort of Asian patients with breast cancer and healthy controls. METHODS: Germ line DNA from a hospital-based study of 2575 unselected patients with breast cancer and 2809 healthy controls were subjected to amplicon-based targeted sequencing of exonic and proximal splice site junction regions of BRCA1 and BRCA2 using the Fluidigm Access Array system, with sequencing conducted on a Illumina HiSeq2500 platform. Variant calling was performed with GATK UnifiedGenotyper and were validated by Sanger sequencing. RESULTS: Fifty-five (2.1%) BRCA1 and 66 (2.6%) BRCA2 deleterious mutations were identified among patients with breast cancer and five (0.18%) BRCA1 and six (0.21%) BRCA2 mutations among controls. One thousand one hundred and eighty-six (46%) patients and 97 (80%) carriers fulfilled the National Comprehensive Cancer Network guidelines for genetic testing. CONCLUSION: Five per cent of unselected Asian patients with breast cancer carry deleterious variants in BRCA1 or BRCA2. While current referral guidelines identified the majority of carriers, one in two patients would be referred for genetic services. Given that such services are largely unavailable in majority of low-resource settings in Asia, our study highlights the need for more efficient guidelines to identify at-risk individuals in Asia.


Assuntos
Proteína BRCA1/genética , Proteína BRCA2/genética , Neoplasias da Mama/genética , Mutação , Adulto , Neoplasias da Mama/etnologia , Neoplasias da Mama/etiologia , Estudos de Casos e Controles , Feminino , Mutação em Linhagem Germinativa , Humanos , Malásia , Pessoa de Meia-Idade , Guias de Prática Clínica como Assunto
6.
Breast Cancer Res ; 18(1): 56, 2016 05 27.
Artigo em Inglês | MEDLINE | ID: mdl-27233495

RESUMO

BACKGROUND: APOBEC3B is a cytosine deaminase implicated in immune response to viral infection, cancer predisposition and carcinogenesis. Germline APOBEC3B deletion is more common in East Asian women and confers a modest risk to breast cancer in both East Asian and Caucasian women. Analysis of tumour samples from women of European descent has shown that germline APOBEC3B deletion is associated with an increased propensity to develop somatic mutations and with an enrichment for immune response-related gene sets. However, this has not been examined in Asian tumour samples, where population differences in genetic and dietary factors may have an impact on the immune system. METHODS: In this study, we determined the prevalence of germline APOBEC3B deletion and its association with breast cancer risk in a cross-sectional hospital-based Asian multi-ethnic cohort of 1451 cases and 1442 controls from Malaysia. We compared gene expression profiles of breast cancers arising from APOBEC3B deletion carriers and non-carriers using microarray analyses. Finally, we characterised the overall abundance of tumour-infiltrating immune cells in breast cancers from TCGA and METABRIC using ESTIMATE and relative frequency of 22 immune cell subsets in breast cancers from METABRIC using CIBERSORT. RESULTS: The minor allelic frequency of APOBEC3B deletion was estimated to be 0.35, 0.42 and 0.16 in female populations of Chinese, Malay and Indian descent, respectively, and that germline APOBEC3B deletion was associated with breast cancer risk with odds ratios of 1.23 (95 % CI: [1.05, 1.44]) for one-copy deletion and 1.38 (95 % CI: [1.10, 1.74]) for two-copy deletion compared to women with no deletion. Germline APOBEC3B deletion was not associated with any clinicopathologic features or the expression of any APOBEC family members but was associated with immune response-related gene sets (FDR q values < 0.05). Analysis of breast cancers from METABRIC revealed breast cancers from APOBEC3B deletion carriers to have significantly higher abundance of tumour-infiltrating immune cells (P < 0.001). CONCLUSIONS: Taken together, our data suggests that tumour-infiltrating immune cells may be an important feature of breast cancers arising in women with APOBEC3B germline deletion, and that this may be of particular interest in Asian women where the germline deletion is more common.


Assuntos
Apresentação do Antígeno , Neoplasias da Mama/genética , Neoplasias da Mama/imunologia , Citidina Desaminase/genética , Predisposição Genética para Doença , Mutação em Linhagem Germinativa , Antígenos de Histocompatibilidade Menor/genética , Deleção de Sequência , Adulto , Neoplasias da Mama/epidemiologia , Neoplasias da Mama/patologia , Estudos de Casos e Controles , Estudos Transversais , Variações do Número de Cópias de DNA , Grupos Étnicos/genética , Feminino , Expressão Gênica , Perfilação da Expressão Gênica , Heterozigoto , Humanos , Imunidade/genética , Linfócitos do Interstício Tumoral/imunologia , Linfócitos do Interstício Tumoral/metabolismo , Malásia/epidemiologia , Malásia/etnologia , Pessoa de Meia-Idade , Isoformas de Proteínas , Risco
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