Chromosome band 17q21 in breast cancer: significant association between beclin 1 loss and HER2/NEU amplification.

Treatment success of breast cancer patients with trastuzumab alone or in combination depends not only on HER2/NEU amplification but also on PTEN and PI3K status and efficient cell death programs. In this pilot study, we found a significant association between loss of beclin 1 and HER2/NEU amplification (both on 17q21) in breast cancers. This finding was confirmed in two public copy number microarray datasets. Furthermore, there is a trend associating beclin 1 loss with TP53 mutations, PI3KCA gene gain, and PTEN mutations. Finally, the observation that beclin 1 gene loss predicted a response to trastuzumab alone or in combination with other drugs is worthy of further confirmation in larger cohorts. Our results suggest that, beclin 1 loss may contribute to genome instability and to a defective autophagy that may lead to tumoral cell death in presence of competent apoptosis or senescence pathways.