Dr Kelly Kiejda

© The Author 2015. Published by Oxford University Press. All rights reserved. Breast cancer is the most common female cancer, but it has relatively low rates of p53 mutations, suggesting other mechanisms are responsible for p53 inactivation. We have shown that the p53 isoform, ¿40p53, is highly expressed in breast cancer, where it may contribute to p53 inactivation. ¿40p53 can be produced by alternative splicing of p53 in intron 2 and this is regulated by the formation of G-quadruplex structures in p53 intron 3, from which the nucleotides forming these structures overlap with a common polymorphism, rs17878362. rs17878362 alters p53 splicing to decrease fully spliced p53 messenger RNA (mRNA) in vitro following ionizing radiation and this in turn alters ¿40p53:p53. Hence, the presence of rs17878362 may be important in regulating ¿40p53:p53 in breast cancer. This study aimed to determine if rs17878362 was associated with altered ¿40p53 and p53 expression and outcome in breast cancer. We sequenced p53 in breast tumours from 139 patients and compared this with ¿40p53 and p53 mRNA expression. We found that the ratio of ¿40p53:p53 was significantly lower in tumours homozygous for the polymorphic A2 allele compared with those who were wild-type (A1/A1). Furthermore, there was a lower proportion of breast cancers carrying the A2 allele from patients who subsequently developed metastasis compared with those that did not. Finally, we show that patients whose tumours carried the polymorphic A2 allele had significantly better disease-free survival. These results show that rs17878362 is associated with a low ¿40p53:p53 ratio in breast cancer and that this is associated with better outcome.

© 2016 The Author(s). Background: The estrogen-induced gene 121 (EIG121) has been associated with breast and endometrial cancers, but its mechanism of action remains unknown. In a genome-wide search for tandem repeats, we found that EIG121 contains a short tandem repeat (STR) in its upstream regulatory region which has the potential to alter gene expression. The presence of this STR has not previously been analysed in relation to breast or endometrial cancer risk. Results: In this study, the lengths of this STR were determined by PCR, fragment analysis and sequencing using DNA from 223 breast cancer patients, 204 endometrial cancer patients and 220 healthy controls to determine if they were associated with the risk of developing breast or endometrial cancer. We found this repeat to be highly variable with the number of copies of the AG motif ranging from 27 to 72 and having a bimodal distribution. No statistically significant association was identified between the length of this STR and the risk of developing breast or endometrial cancer or age at diagnosis. Conclusions: The STR in the upstream regulatory region of EIG121 is highly polymorphic, but is not associated with the risk of developing breast or endometrial cancer in the cohorts analysed here. While this polymorphic STR in the regulatory region of EIG121 appears to have no impact on the risk of developing breast or endometrial cancer, its association with disease recurrence or overall survival remains to be determined.

© 2015 by The American Society for Biochemistry and Molecular Biology, Inc. Brain metastases are a devastating consequence of cancer and currently there are no specific biomarkers or therapeutic targets for risk prediction, diagnosis, and treatment. Here the proteome of the brain metastatic breast cancer cell line 231-BR has been compared with that of the parental cell line MDA-MB-231, which is also metastatic but has no organ selectivity. Using SILAC and nanoLC-MS/MS, 1957 proteins were identified in reciprocal labeling experiments and 1584 were quantified in the two cell lines. A total of 152 proteins were confidently determined to be up- or down-regulated by more than twofold in 231-BR. Of note, 112/152 proteins were decreased as compared with only 40/152 that were increased, suggesting that down-regulation of specific proteins is an important part of the mechanism underlying the ability of breast cancer cells to metastasize to the brain. When matched against transcriptomic data, 43% of individual protein changes were associated with corresponding changes in mRNA, indicating that the transcript level is a limited predictor of protein level. In addition, differential miRNA analyses showed that most miRNA changes in 231-BR were up- (36/45) as compared with down-regulations (9/45). Pathway analysis revealed that proteome changes were mostly related to cell signaling and cell cycle, metabolism and extracellular matrix remodeling. The major protein changes in 231-BR were confirmed by parallel reaction monitoring mass spectrometry and consisted in increases (by more than fivefold) in the matrix metalloproteinase-1, ephrin-B1, stomatin, myc target-1, and decreases (by more than 10-fold) in transglutaminase-2, the S100 calcium-binding protein A4, and L-plastin. The clinicopathological significance of these major proteomic changes to predict the occurrence of brain metastases, and their potential value as therapeutic targets, warrants further investigation.

© 2015 by the authors; licensee MDPI, Basel, Switzerland. Triple negative breast cancer (TNBC) is characterised by the lack of receptors for estrogen (ER), progesterone (PR), and human epidermal growth factor 2 (HER2). Since it cannot be treated by current endocrine therapies which target these receptors and due to its aggressive nature, it has one of the worst prognoses of all breast cancer subtypes. The only treatments remain chemo- and/or radio-therapy and surgery and because of this, novel biomarkers or treatment targets are urgently required to improve disease outcomes. MicroRNAs represent an attractive candidate for targeted therapies against TNBC, due to their natural ability to act as antisense interactors and regulators of entire gene sets involved in malignancy and their superiority over mRNA profiling to accurately classify disease. Here we review the current knowledge regarding miRNAs as biomarkers in TNBC and their potential use as therapeutic targets in this disease. Further, we review other epigenetic changes and interactions of these changes with microRNAs in this breast c ancer subtype, which may lead to the discovery of new treatment targets for TNBC.

Triple negative breast cancer (TNBC) is the most aggressive breast cancer subtype with the worst prognosis and no targeted treatments. TNBC patients are more likely to develop metastases and relapse than patients with other breast cancer subtypes. We aimed to identify TNBC-specific genes and genes associated with lymph node metastasis, one of the first signs of metastatic spread. A total of 33 TNBCs were used; 17 of which had matched normal adjacent tissues available, and 15 with matched lymph node metastases. Gene expression microarray analysis was used to reveal genes that were differentially expressed between these groups. We identified and validated 66 genes that are significantly altered when comparing tumours to normal adjacent samples. Further, we identified 83 genes that are associated with lymph node metastasis and correlated these with miRNA-expression. Pathway analysis revealed their involvement in DNA repair, recombination and cell death, chromosomal instability and other known cancer-related pathways. Finally, four genes were identified that were specific for TNBC, of which one was associated with overall survival. This study has identified novel genes involved in LN metastases in TNBC and genes that are TNBC specific that may be used as treatment targets or prognostic indicators in the future.

Triple-negative breast cancer (TNBC) is a tumour classification that is defined by oestrogen receptor, progesterone receptor and human epidermal growth factor receptor 2 receptor negativity. TNBCs share a similar gene expression profile to BRCA-mutated tumours, have been shown to carry a high proportion of BRCA mutations and have a more adverse prognosis compared to other types of breast tumours. PALB2 has been shown to be a moderate-penetrance breast cancer susceptibility gene and is involved in the same DNA damage repair pathway as BRCA1 and BRCA2; this raises the possibility that germline PALB2 mutations may be involved in the pathogenesis of TNBCs. In our study, we sequenced the coding regions of PALB2 (including intron/exon boundaries) in genomic DNA from 347 patients diagnosed with TNBC to determine the prevalence of deleterious mutations in this population. Two novel truncating mutations (c.758dup and c.2390del) and one previously detected truncating mutation (c.3113+5G > C) were found. In addition, five variants predicted to be protein-affecting were also identified. Our study shows that the prevalence of PALB2 germline mutations in individuals with TNBC is ~1%, similar to the prevalence of PALB2 germline mutation of 1% in familial non-BRCA1/2 breast cancer cohorts. © 2013 UICC.

Background: Breast cancer is the most common malignancy that develops in women, responsible for the highest cancer-associated death rates. Triple negative breast cancers represent an important subtype that have an aggressive clinical phenotype, are associated with a higher likelihood of metastasis and are not responsive to current targeted therapies. miRNAs have emerged as an attractive candidate for molecular biomarkers and treatment targets in breast cancer, but their role in the progression of triple negative breast cancer remains largely unexplored.Methods: This study has investigated miRNA expression profiles in 31 primary triple negative breast cancer cases and in 13 matched lymph node metastases compared with 23 matched normal breast tissues to determine miRNAs associated with the initiation of this disease subtype and those associated with its metastasis.Results: 71 miRNAs were differentially expressed in triple negative breast cancer, the majority of which have previously been associated with breast cancer, including members of the miR-200 family and the miR-17-92 oncogenic cluster, suggesting that the majority of miRNAs involved in the initiation of triple negative breast cancer are not subtype specific. However, the repertoire of miRNAs expressed in lymph node negative and lymph node positive triple negative breast cancers were largely distinct from one another. In particular, miRNA profiles associated with lymph node negative disease tended to be up-regulated, while those associated with lymph node positive disease were down-regulated and largely overlapped with the profiles of their matched lymph node metastases. From this, 27 miRNAs were identified that are associated with metastatic capability in the triple negative breast cancer subtype.Conclusions: These results provide novel insight into the repertoire of miRNAs that contribute to the initiation of and progression to lymph node metastasis in triple negative breast cancer and have important implications for the treatment of this breast cancer subtype. © 2014 Avery-Kiejda et al.; licensee BioMed Central Ltd.