Direct Regulation of Estrogen Receptor Transcription Activity by NF1

ABSTRACT

This project centers on the NF1/neurofibromin tumor suppressor, which was best known as a GTPase Activating Protein (GAP)that repress Ras activity. The parent DoD award has successfully defined a new and GAP-independent activity that NF1 is also a transcriptional co-repressor for estrogen receptor (ER) in ER+ breast cancer. While the parent DoD award focused on endocrine therapy resistance caused by NF1 loss, in this Expansion Award, the focus instead is on metastasis, for which currently has no cure. An important feature of ER+ breast cancer metastasis is that greater than 70% of the metastasis is in the bone. We hypothesized that the transcriptional co-repressor role of NF1 is also responsible for driving bone metastasis in ER+ breast cancer. Therefore, the objective of this Expansion Award is to assess NF1s role in metastasis in order to establish a strategy to stop it. We have made progress in accomplish Task1/Aim 1 to fully define NF1-controlled genes that can impact bone metastasis. This was a key part of the data that was just published in the high impact journal Cancer Cell. This award has also supported the launching a Phase-II clinical trial to treat ER+ NF1-depleted breast cancer, and the awards of a SPORE and another DoD Level-2 project. However, in Aim 2 (Tasks 2 and 30) we are dependent on the use of animals to study how NF1-depleted cancer cells interact with the bone, but this line of study has been severely and negatively impacted by COVID-19. We discuss how we plan to overcome this problem in the future.