microRNAs are small, non-coding RNAs that influence gene expression on a post-transcriptional level. They participate in diverse biological pathways and may act as either tumor suppressor genes or oncogenes. As they may have an effect on thousands of target mRNAs, single-nucleotide polymorphisms in microRNA genes might have major functional consequences, because the microRNA's properties and/or maturation may change. miR-196a has been reported to be aberrantly expressed in breast cancer tissue. Additionally, the SNP rs11614913 in hsa-mir-196a-2 has been found to be associated with breast cancer risk in some studies although not in others. This study evaluated the association between rs11614913 and breast cancer risk in a Caucasian case-control cohort in Queensland, Australia. Results do not support an association of the tested hsa-mir-196a-2 polymorphism with breast cancer susceptibility in this cohort. As there is a discrepancy between our results and previous findings, it is important to assess the role of rs11614913 in breast cancer by further larger studies investigating different ethnic groups.

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The goal of improving systemic treatment of breast cancers is to evolve from treating every patient with non-specific cytotoxic chemotherapy/hormonal therapy, to a more individually-tailored direct treatment. Although anatomic staging and histological grade are important prognostic factors, they often fail to predict the clinical course of this disease. This study aimed to develop a gene expression profile associated with breast cancers of differing grades. We extracted mRNA from FFPE archival breast IDC tissue samples (Grades I-III), including benign tumours. Affymetrix GeneChip(®) Human Genome U133 Plus 2.0 Arrays were used to determine gene expression profiles and validated by Q-PCR. IHC was used to detect the AXIN2 protein in all tissues. From the array data, an independent group t-test revealed that 178 genes were significantly (P ≤ 0.01) differentially expressed between three grades of malignant breast tumours when compared to benign tissues. From these results, eight genes were significantly differentially expressed in more than one comparison group and are involved in processes implicated in breast cancer development and/or progression. The two most implicated candidates genes were CLD10 and ESPTI1 as their gene expression profile from the microarray analysis was replicated in Q-PCR analyses of the original tumour samples as well as in an extended population. The IHC revealed a significant association between AXIN2 protein expression and ER status. It is readily acknowledged and established that significant differences exist in gene expression between different cancer grades. Expansion of this approach may lead to an improved ability to discriminate between cancer grade and other pathological factors.

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Before the age of 75 years, approximately 10% of women will be diagnosed with breast cancer, one of the most common malignancies and a leading cause of death among women. The objective of this study was to determine if expression of the nuclear receptor coactivators 1 and 3 (NCoA1 and NCoA3) varied in breast cancer grades. RNA was extracted from 25 breast tumours and transcribed into cDNA which underwent semi-quantitative polymerase chain reaction, normalised using 18S. Analysis indicated that an expression change for NCoA1 in cancer grades and estrogen receptor alpha negative tissue (P= 0.028 and 0.001 respectively). NCoA1 expression increased in grade 3 and estrogen receptor alpha negative tumours, compared to controls. NCoA3 showed a similar, but not significant, trend in grade and a non-significant decrease in estrogen receptor alpha negative tissues. Expression of NCoA1 in late stage and estrogen receptor alpha negative breast tumours may have implications to breast cancer treatment, particularly in the area of manipulation of hormone signalling systems in advanced tumours.