Beta-catenin expression patterns in matched pre- and post-neoadjuvant chemotherapy-resistant breast cancer.

Background: β-catenin is a critical component of the cadherin cell-to-cell adhesion pathway and a key participant in the Wnt signaling pathway. Activation of β-catenin signaling in the Wnt pathway is a known contributor to tumor cancer progression and metastasis and may result in resistance to chemotherapeutic agents. The aim of this study is to evaluate the patterns of expression of β-catenin in breast carcinoma cells before and after neoadjuvant chemotherapy. Discovery of the molecular mechanisms responsible for resistance to chemotherapy treatment could result in more effective therapy, and improve outcome and survival.

Design: Twenty-nine matched pre-treatment and post-neoadjuvant chemotherapy breast carcinomas were subjected to immunohistochemical study using anti-β-catenin antibody. Normal staining was defined as crisp membrane staining in >90% tumor cells; aberrant expression was nuclear staining in >5% tumor cells.

Results: Of the 29 included cases, five cases of invasive lobular carcinoma lacked β-catenin immunoreactivity pre- and post-treatment. Mildly reduced membranous staining was seen in two post-treatment samples. One case of triple-negative ductal carcinoma had reduced pre- and post-treatment staining. All other cases showed normal pre- and post-treatment β-catenin expression. No aberrant staining was identified.

Conclusion: In our study, there was no difference in the expression of β-catenin in pre- and post-neoadjuvant chemotherapy specimens. These results do not suggest that β-catenin plays a role in conferring neoadjuvant chemotherapy resistance.