Abstract P2-11-35: A tight junctional scaffold protein MUPP1/MPDZ and its docking proteins, angiomotins in breast cancer

Abstract A tight junctional scaffold protein MUPP1/MPDZ and its docking proteins, angiomotins in breast cancer Han Gao1, Fiona Ruge1, Lin Ye1, Jane Lane1, Eleri Davies2, Wen G. Jiang1, Tracey A. Martin1 1Cardiff University School of Medicine, Heath Park, Cardiff CF14 4XN, UK 2Wales Breast Centre, University Llandough Hospital, Cardiff CF64 2XX, UK Introduction. MUPP1 (Multiple PDZ Domain Crumbs Cell Polarity Complex Component) or MPDZ is a scaffold protein with multiple PDZ domains, critical for multiple protein docking and protein-protein interactions in cells. MUPP1 is particularly interesting as it offers docking sites for a number of tight junction (TJ) proteins and proteins known to regulate cell junction and motility, including angiomotin (AMOT) and angiomotin-like proteins, the latter being important in regulating cell migration of endothelial cells and an important member in TJ protein complexes. The MUPP1 protein complex at cell junctions also includes CAR/CXADR (coxsackie adenovirus receptor) and members of the ERM (Moesin-Ezrin-Radixin) protein family. It was proposed that the junctional-related MUPP1 docking protein complex may collectively have a role in the development and progression of cancer including breast cancer. The present study examined the profile and integrated expression of these MUPP1 docking molecules in relationship with the outcome, clinical and pathological factors of breast cancer. Methods. Using the datasets of an existing breast cancer cohort at Cardiff, we visited the expression profile of the MUPP1/MPDZ docking molecules including MUPP1, four members of the ERM family, including ezrin, moesin, radixin and EHM2 (also known as NF2) and CAR/CXADR (coxsackie adenovirus receptor). The profile and integrated expression of the profile were analysed against clinical, pathological and outcome factors and also the hormone receptor status of breast cancers. Results. MUPP1 is a weakly linked to the disease progression, so as angiomotin, angiomotin-like1 and angiomotin-like2. Alone, only EHM2 showed significance in linking with the survival of the patient’s OS (p=0.38), neither of the remaining MUPP1 complex molecules, including MUPP1, AMOT, AMOTL1, AMOTL2, ezrin, moesin and radixin was able to offer a significant predictive value for the survival of the patients. However, it was found that MUPP1 has a significant correlation with AMOTs, EHM2 and ezrin. When these significantly correlated molecules were integrated in the analysis, the integrated expression pattern showed a highly significant value in evaluating the overall survival (p=0.003) and disease-free survival (p=0.007). Both of these predictive powers are independent in a multivariate analyses including the clinical and hormone receptors for OS (p=0.022, Hazard Ratio (HR)=1.352 95%CI (1.044-1.752)) and RFS (p=0.023, HR=1.241 (95% CI. 1.031-1.498)). It was interesting to note that the link between the expression pattern and OS was more prominent in ER negative (p=0.018) than in ER positive tumours (p=0.177). The same was observed with disease free survival for ER negative (p=0.011) compared with ER positive (p=0.462) tumours. Non-triple negative breast cancer had shown a similar sensitivity compared with triple negative breast cancer. Discussion. MUPP1, a PDZ domain containing docking protein closed linked with TJ structure, forms an interesting expression profile with its docking molecules including angiomotins and EHM2 that allows evaluation of disease progress and clinical outcome of the patients with breast cancer. Citation Format: Han Gao, Fiona Ruge, Lin Ye, Jane Lane, Eleri Davies, Wen G. Jiang, Tracey A. Martin. A tight junctional scaffold protein MUPP1/MPDZ and its docking proteins, angiomotins in breast cancer [abstract]. In: Proceedings of the 2022 San Antonio Breast Cancer Symposium; 2022 Dec 6-10; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2023;83(5 Suppl):Abstract nr P2-11-35.