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. Expression patterns of co-localised cancer-associated genes at 17q12-21 were examined using RT-PCR. The study group consisted of a 96-patient cohort. Relative quantity of mRNA expression was calculated using the comparative cycle threshold method and Qbase software. Results were analysed to detect expression patterns among the genes, 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). GRB7 was 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-negative patients (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 significantly higher 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 clinically as HER2/neu-positive (p=0.004). This study reaffirms the correlation between HER2/neu and the co-localised LASP1 and GRB7; the latter target may hold additional significance in addition to being a surrogate marker for HER2/neu expression. The relationship identified between RARA and ER-positivity may herald an avenue for targeted therapy of these tumours.