Abstract P3-07-06: TRIM44 is a possible poor prognostic factor for breast cancer patients and positively regulates NF-κB signaling pathway
Authors: Kawabata H , Azuma K , Ikeda K , Sugitani I , Kinowaki K , Fujii T , Osaki A , Saeki T , Horie-Inoue K , Inoue S 
Published: February 2018

[Background]

Many of the tripartite motif (TRIM) proteins, like Efp/TRIM25 which was identified by our group previously (Nature 417, 871-875, 2002), function as E3 ubiquitin ligases, and are thought to be involved in various physiological and pathological processes such as immunity and oncogenesis. In regard to tripartite motif containing 44 (TRIM44), which is an atypical TRIM family protein lacking RING finger domain, some evidences suggest that it is implicated in the progression of several human malignancies. But its pathophysiological significance in breast cancer remains unknown.

[Methods]

In the present study, immunohistochemical analysis using anti-TRIM44 antibody was performed in clinical breast cancer tissues from 129 patients with the approval of institutional ethical committees (approval number: 845). We then explored the pathophysiological role of TRIM44 in breast cancer by modulating TRIM44 expression in MCF-7 and MDA-MB-231 breast cancer cells.

[Results]

TRIM44 strong immunoreactivity was significantly associated with nuclear grade, distant disease-free survival and overall survival of the breast cancer patients. With multivariate analysis it was shown that the TRIM44 status was an independent prognostic factor for distant disease-free survival and overall survival. The proliferation of MCF-7 and MDA-MB-231 cells was significantly decreased by siRNA-mediated TRIM44 knockdown. TRIM44 knockdown also suppressed migration of MDA-MB-231 cells. Microarray analysis and qRT-PCR revealed that TRIM44 knockdown upregulated CDK19 (Cyclin Dependent Kinase 19), which is reported to be a tumor suppressor gene, whereas downregulated MMP1 (Matrix Metallopeptidase 1) in MDA-MB-231 cells. Notably, TRIM44 knockdown impaired nuclear factor-kappa B (NF-κB)-mediated transcriptional activity stimulated by tumor necrosis factor α (TNFα). Moreover, TRIM44 knockdown substantially attenuated the TNFα-dependent phosphorylation of p65 subunit of NF-κB and IκBα in both MCF-7 and MDA-MB-231 cells.

[Discussion]

Our clinical study showed that prognosis of breast cancer patients is correlated with the immunoreactivity detected by anti-TRIM44 antibody. This result suggested that expression of TRIM44 protein could be used as a potential biomarker of breast cancer. We demonstrated that NF-κB signaling pathway is modulated by TRIM44. Since NF-κB augmentation is shown to be related to aggressive character of breast cancer, stimulation of NF-κB signaling with TRIM44 might be underlying mechanism of poor prognosis. Our in vitro study showed TRIM44 knockdown caused attenuated proliferation and migration of breast cancer cells, raising the possibility of TRIM44 as a potential therapeutic target for breast cancer. These findings provide new clues to develop alternative effective strategies for breast cancer management.

Citation Format: Kawabata H, Azuma K, Ikeda K, Sugitani I, Kinowaki K, Fujii T, Osaki A, Saeki T, Horie-Inoue K, Inoue S. TRIM44 is a possible poor prognostic factor for breast cancer patients and positively regulates NF-κB signaling pathway [abstract]. In: Proceedings of the 2017 San Antonio Breast Cancer Symposium; 2017 Dec 5-9; San Antonio, TX. Philadelphia (PA): AACR; Cancer Res 2018;78(4 Suppl):Abstract nr P3-07-06.