Abstract 5390: Exploring signaling pathways of tumor-nerve interactions in prostate and breast cancer
Authors: Hwang Bor-Jang , Edwards Gabrielle J. , Knoblich Cole Davis , Rezvani Khosrow , Odero-Marah Valerie 
Published: March 2024

Abstract
A significant portion of prostate cancer (PCa) and breast cancer (BCa) patients develop bone metastatic disease. In some cases, cancer spreads through the nervous system, a process known as perineural invasion (PNI). Neurite outgrowth is believed to be a precursor to PNI. Snail is an important gene which regulates the epithelial-mesenchymal transition (EMT) process in which tumor cells at the invasive front undergo this transition to promote invasion, migration, and subsequent metastasis. We recently published that Snail promotes neurite outgrowth in PCa cells. We hypothesize that Snail expression will stimulate neurite outgrowth in both PCa and BCa cells through extracellular vesicles from cancer cells interacting with neurons. To test this hypothesis, we first collected conditioned media from PCa and BCa cells expressing Snail and isolated exosomes. Exosomal markers were detected using western blot to confirm the isolated exosomes. Additionally, we used Transmission Electron Microscopy (TEM) to observe the secretion of exosomes. Proteomics was performed to analyze proteins expressed within exosomes of LNCaP Snail overexpressing or C4-2 Snail knockdown PCa cells. Our results showed that Snail-expressing cells secrete exosomes containing Talin1, specifically, the proteolyzed C-terminal rod domain, while full-length Talin1 is found in whole cell lysates from Snail-expressing cells. Talin1 has previously been associated with neurite outgrowth. Neurite outgrowth assays were then performed using conditioned medium collected from C4-2 PCa cells with Snail knockdown and MCF-7 BCa cells with Snail overexpression. Increased neurite outgrowth is observed in PC-12 cells and NPC (Induced Pluripotent Stem Cells differentiated neuronal progenitor cells) when cultured with conditioned medium collected from PCa and BCa cells expressing high levels of Snail. AKT activation was observed in the neuronal cells in response to conditioned media from Snail-expressing cells. Furthermore, we found that mH4, a proprietary small molecule inhibitor of Talin1, reduces Snail-mediated neurite outgrowth and AKT activation (p-AKT Thr308 and Ser473). Overall, we have uncovered a pathway whereby Snail transcription factor promotes secretion of exosomes containing Talin1 which promotes AKT signaling in neuronal cells and neurite outgrowth. Talin1 small molecule inhibitor shows promise for therapeutic targeting of tumor-nerve interactions.
Acknowledgements: The authors acknowledge the use of core facilities supported by the National Institute on Minority Health and Health Disparities through grant number 5U54MD013376 and 1U54GM128729-01-DaCCoTA Scholars Program (PI: Rezvani) National Institute of General Medical Sciences (NIGMS).
Citation Format: Bor-Jang Hwang, Gabrielle J. Edwards, Cole Davis Knoblich, Khosrow Rezvani, Valerie Odero-Marah. Exploring signaling pathways of tumor-nerve interactions in prostate and breast cancer [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 5390.