Expression levels of HER2/neu and those of collocated genes at 17q12-21, in breast cancer

HER2/neu is associated with poorer clinical outcome in breast cancer. Expressionpatterns of co-localised cancer-associated genes at 17q12-21 were examined usingRT-PCR. The study group consisted of a 96-patient cohort. Relative quantity ofmRNA expression was calculated using the comparative cycle threshold method andQbase software. Results were analysed to detect expression patterns among thegenes, and to identify associations between expression levels and clinical data.Levels of HER2/neu correlated with those of GRB7 (r=0.551, p<0.001), RARA (r=0.391,p<0.001), RPL19 (r=0.549, p<0.001) and LASP1 (r=0.399, p<0.001). GRB7was significantly inversely associated with improved DFS at 60 months (p=0.036).RARA levels were greater in HER2/neu-positive as opposed to HER2/neu-negativepatients (p=0.021); levels were significantly higher in ER-positive patients,relative to those who were ER-negative (p=0.003). Levels of RPL19 were significantlyhigher in the HER2/neu-overexpressing (p=0.010) and luminal B subtypes (p=0.007).LASP1 levels were higher in those patients who had been classified clinicallyas HER2/neu-positive (p=0.004). This study reaffirms the correlation between HER2/neuand the co-localised LASP1 and GRB7; the latter target may hold additional significancein addition to being a surrogate marker for HER2/neu expression. The relationshipidentified between RARA and ER-positivity may herald an avenue for targeted therapyof these tumours.