Figure 1

The correlation between high level ERα36 expression in human breast cancer and increased metastasis. (A) Generation of a monoclonal antibody-recognizing ERα36. The specificity of the antibody was verified by IHC staining. (B) Detection of ERα36 by the monoclonal antibody in primary breast cancer tissues with or without ERα66 expression. Brown staining denotes the immunoreactivity of ERα36 or ERα66. Tumor sections were counterstained by Hematoxylin to label nuclei. Scale bar, 50 μm (Supplementary information, Table S1). (C) ERα36 expression (red arrows) in the invasive front (dotted line) of a primary breast cancer and in a metastatic lymph node. Brown staining denotes ERα36 immunoreactivity. Scale bar, 50 μm. (D) Higher percentage of lymph node metastases shown by ERα36⁺ breast cancer as compared to ERα36⁻ cancer. Data were analyzed using Pearson's χ² test. (E, F) Kaplan-Meier estimation of metastasis-free survival (MFS) of patients with ERα36⁺ or ERα36⁻ breast cancer in conjunction with ERα66 positivity. P value was calculated with two-sided log-rank tests. (G) The metastasis hazard ratio of ERα36 expression in breast cancer of independent patient cohorts analyzed with Forest Plot. The size of each square is proportional to the number of patients in each cohort. The area of the squares reflects the study-specific weight. Horizontal lines represent 95% confidence intervals (CI). Diamonds represent the pooled risk ratio and 95% CI of ERα36 expression.