Opioids drive breast cancer metastasis through the δ-opioid receptor and oncogenic STAT3

• Main Authors: Sabrina Tripolt, Heidi A. Neubauer, Vanessa M. Knab, Dominik P. Elmer, Fritz Aberger, Richard Moriggl, Daniela A. Fux
• Format: Article
• Language: English
• Published: Elsevier 2021-02-01
• Series: Neoplasia: An International Journal for Oncology Research
• Subjects: Breast cancer; STAT3; Opioid; Metastasis; EMT
• Online Access: http://www.sciencedirect.com/science/article/pii/S1476558621000014

The opioid crisis of pain medication bears risks from addiction to cancer progression, but little experimental evidence exists. Expression of δ-opioid receptors (DORs) correlates with poor prognosis for breast cancer patients, but mechanistic insights into oncogenic signaling mechanisms of opioid-triggered cancer progression are lacking. We show that orthotopic transplant models using human or murine breast cancer cells displayed enhanced metastasis upon opioid-induced DOR stimulation. Interestingly, opioid-exposed breast cancer cells showed enhanced migration and strong STAT3 activation, which was efficiently blocked by a DOR-antagonist. Furthermore, opioid treatment resulted in down-regulation of E-Cadherin and increased expression of epithelial-mesenchymal transition markers. Notably, STAT3 knockdown or upstream inhibition through the JAK1/2 kinase inhibitor ruxolitinib prevented opioid-induced breast cancer cell metastasis and migration in vitro and in vivo. We conclude on a novel mechanism whereby opioid-triggered breast cancer metastasis occurs via oncogenic JAK1/2-STAT3 signaling to promote epithelial-mesenchymal transition. These findings emphasize the importance of selective and restricted opioid use, as well as the need for safer pain medication that does not activate these oncogenic pathways.