Abstract 4607: TRPS1 inhibits angiogenesis in triple negative breast cancer down regulating JAG1 and TYMP genes involved in angiogenesis pathways

Abstract

Abstract Background. Triple-negative breast cancer (TNBC), the most difficult subtype to treat, is defined as estrogen receptor, HER2, and progesterone receptor negative. TNBC constitutes 10-20% of all breast cancer and has a higher rate of distal recurrence and a poorer prognosis than other breast cancer subtypes. Less than 30% of women with metastatic TNBC survive 5 years and almost all die from their disease despite adjuvant chemotherapy. Angiogenesis is a critical factor in the development of tumors and metastases in numerous cancers. Clinical trials with anti-angiogenic drugs showed to be inadequate, with moderate response rates and insignificant survival gains for patients. To understand the genetic forces involved in TNBC, we performed a transposon mutagenesis screen in Pten mutant mice that identified several candidate trunk drivers and progression genes. A major finding of our screen was the discovery and functional validation of, Trichorhinophalangeal syndrome type 1 (TRPS1), a GATA-like transcription factor, which functions as a transcriptional repressor or activator, depending on cell type, stage of development, or pathological conditions. Based on this data, we explored the role of TRPS1 in angiogenesis. Methods and Results. Tube formation and sprouting assays were performed using overexpression and inactivation of TRPS1 in MDA-MD-231 and HCC70 cells, respectively. Interestingly, inactivation of TRPS1 expression accelerates tube formation structures compared to the vector control as well as cell branching in the sprouting assay. Overexpression of TRPS1 prevents tubing and branching formation in vitro assays. Moreover, immunohistochemistry staining of CD31 detected a reduced number of blood vessels in MDA-MB-231 tumor xenografts overexpressing TRPS1, and an increase of angiogenic vasculature in HCC70 TRPS1-shRNA tumor xenografts. In vitro and in vivo assays demonstrate the role of TRPS1 in tumor angiogenesis. Furthermore, human ChIP qPCR angiogenesis array identified 10 top candidate genes potentially regulated by TRPS1 transcription factor. Of these candidates, JAG1 and TYMP showed to have a higher fold enrichment compared to other angiogenic related genes. Finally, we validated its direct functional binding by using luciferase reporter assay, such demonstrated that TRPS1 is a direct transcriptional regulator of JAG1 and TYMP. Conclusion. TRPS1 is a tumor suppressor involved in the mechanisms regulating tumor angiogenesis by repressing the expression of JAG1 and TYMP genes in TNBC. Citation Format: Liliana Guzman. TRPS1 inhibits angiogenesis in triple negative breast cancer down regulating JAG1 and TYMP genes involved in angiogenesis pathways. [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2023; Part 1 (Regular and Invited Abstracts); 2023 Apr 14-19; Orlando, FL. Philadelphia (PA): AACR; Cancer Res 2023;83(7_Suppl):Abstract nr 4607.