TGFB-Induced Factor Homeobox 1 (TGIF) Expression in Breast Cancer

Abstract Background: Breast cancer (BC) is the most frequent female cancer its which preferentially metastasizes to bone. Mechanisms of bone tropism are poorly understood, however, the transcription factor TGFB-induced factor homeobox 1 (TGIF) is involved in bone metabolism and thus of potential interest.Methods: TGIF expression was analyzed by immunohistochemistry in 1197 formalin-fixed, paraffin-embedded tissue from BC patients treated in the GAIN study with two adjuvant dose-dense schedules of chemotherapy with or without bisphosphonate ibandronate. TGIF expression was categorized into negative/low and moderate/strong staining.Results: In 1197 samples, we found associations of higher TGIF protein expression with smaller tumor size (p = 0.015), well differentiated phenotype (p < 0.001) and estrogen receptor (ER)-positive BC (p < 0.001). Patients with higher TGIF expression levels showed a significantly better disease-free (log-rank p 0.019) and overall survival (log-rank p = 0.018), but no association with time to bone metastasis as first site of relapse. Stratified univariate analysis in molecular subgroups emphasized that elevated TGIF expression was prognostic for both DFS and OS in ER-positive BC patients (DFS: log-rank p = 0.009; OS: log-rank p = 0.008) and in the HER2-negative subgroup (DFS: log-rank p = 0.004; OS: log-rank p = 0.002).Conclusions: Our findings suggest that a loss of TGIF expression is associated with BC progression, especially in luminal carcinomas.Trial registration: This clinical trial has been registered with ClinicalTrials.gov; registration number: NCT00196872.