Relative levels of let  -7a, XXXX , @entity13825 , @entity6557 , miR  -125b and @entity21275 as potential molecular markers to evaluate grade, receptor status and molecular type in @entity0 .

@entity13825 @entity1 @entity21275 @entity0 @entity12425 @entity5 @entity6557 @entity2931 @entity1420 @entity60709 @entity56256 @entity4149 @entity1722
UNASSIGNED: MicroRNAs (miRNAs/miRs) are a class of short, single  -stranded nucleic acids, which have been investigated as potential molecular markers for various types of @entity5 . The gold  -standard and most sensitive method for comparing miRNA levels in @entity5 tissues is reverse transcription  -quantitative polymerase chain reaction (RT  -qPCR). This technique uses stably expressed genes for normalisation. The aim of the present study was to improve this model of analysis in the context of RT  -qPCR results. A total of six known miRNAs (let  -7a, @entity12425 , @entity13825 , @entity6557 , miR  -125b and @entity21275 ), @entity60709 RNA and five mRNAs [erb  -b2 receptor @entity4149 kinase  2 ( @entity1722 ), @entity56256 synthase and polymerase (RNA)  II (DNA directed) polypeptide A] were analysed pair  -wise, in order to determine which biomarker pairs best correlated with the histological groups of 27  @entity0 samples. The lowest P  -values and the highest area under the curve values in the receiver operating characteristic analysis were used to select the optimum ratios for discrimination among groups. Among the 21 pairs, @entity12425 / @entity13825 and @entity6557 / @entity60709 best discriminated three groups of samples with different @entity5 grades (G  classification). miR  -125b/ @entity21275 best discriminated two groups of samples with different @entity5 sizes (pT), let  -7a/ @entity60709 best discriminated two groups of samples with different lymph node status (pN), and let  -7a/miR  -125b best discriminated groups of samples with negative and positive @entity2931 and @entity1420 receptor status. No pair of miRNAs was found to discriminate well between groups with either a negative or positive @entity1 @entity1722 ( @entity1722 ) status. However, one miRNA/mRNA pair, @entity6557 / @entity1722 , discriminated @entity1722  -negative from @entity1722  -positive groups. The @entity0 samples investigated in the present study were grouped by immunohistological methods into three molecular classes: Luminal, @entity1722 positive and basal (L, H and B, respectively). In order to discern L from H and L from B, two miRNA pairs were selected: @entity6557 /miR  -125b and @entity6557 / @entity21275 . In conclusion, the pair  -wise method of RT  -qPCR data analysis may be a reasonable alternative to the standard method of using stably expressed reference genes, such as @entity60709 RNA, for normalisation. This method may increase the classification power of miRNA biomarkers in @entity0 diagnostics.
