Abstract PO5-04-10: Clinical and prognostic value of MLN51 (Metastatic lymph node gene 51)/CASC3 (Cancer susceptibility candidate gene 3) in clinical breast cancer, connection with nodal and hormonal receptor status

Abstract Introduction: Metastatic Lymph Node Gene 51 Protein (MLN51) also known as Cancer Susceptibility Candidate Gene 3 Protein (CASC3) or Barentsz (BTZ) is a molecule that was first identified in malignant breast tumours. The CASC3 gene encodes the protein that binds to mRNA and is a key component of the exon junction complex (EJC), playing an important role in the metabolism of mRNA and in cellular recovery after stress responses. It is not clear, however, if MLN51 has a clinical value in assessing the disease progression of breast cancer. Methods: We analysed the transcription expression levels of MLN51 in a cohort of human breast cancer tissues and correlated the expression pattern with clinical outcome, pathological type and hormonal receptor status. Results: High levels of MLN51 was found to be a favourable prognostic indicator for overall survival (p=0.008, Hazard Ratio HR=0.262), the prognostic value being independent of other clinical and pathological factors. Likewise, high levels of MLN51 were also a significant and independent predictive factor for disease free survival (DFS) (p=0.003, HR=0.262). It was found that the favourable prediction in both OS and DFS was associated with node positive tumours, with significance with OS (p=0.004), compared in node negative tumours (p=0.143) and to DFS (p=0.001 in node positive compared with p=0.079 in node negative tumours). Levels of MLN51 had a significant correlation with EGFR in both normal and tumour mammary tissues but correlated with Her-2 and Her-3 in tumour tissues only. The prognostic power of MLN51 for DFS was significant in both Her-2 positive and Her-2 negative (p=0.003 and p=0.012) tumours and in ER negative tumours (p=0.003). The prediction for OS by MLN51 was particularly strong for Her-2 positive and ER positive (p=0.007 for both) tumours. Conclusions: MLN51 (CASC3) is a favourable prognostic factor in patients with breast cancer. This is clearly linked to the nodal status and hormone receptor status, particularly ER and HER-2. Citation Format: Binbin Cong, Tracey Martin, Xiaoshan Cao, Robert E Mansel, Eleri Davies, Wen Jiang. Clinical and prognostic value of MLN51 (Metastatic lymph node gene 51)/CASC3 (Cancer susceptibility candidate gene 3) in clinical breast cancer, connection with nodal and hormonal receptor status abstract. In: Proceedings of the 2023 San Antonio Breast Cancer Symposium; 2023 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2024;84(9 Suppl):Abstract nr PO5-04-10.