Activation of HIF-1αbyδ-Opioid Receptors Induces COX-2 Expression in Breast Cancer Cells and Leads to Paracrine Activation of Vascular Endothelial Cells

Abstract

Opioids promote tumor angiogenesis in mammary malignancies, but the underlying signaling mechanism is largely unknown. The current study investigated the hypothesis that stimulation of d-opioid receptors (DOR) in breast cancer (BCa) cells activates the hypoxia-inducible factor 1a (HIF-1a), which triggers synthesis and release of diverse angiogenic factors. Immunoblotting revealed that incubation of human MCF-7 and T47D breast cancer cells with the DOR agonist D-Ala 2 ,D-Leu 5-enkephalin (DADLE) resulted in a transient accumulation and thus activation of HIF-1a. DADLE-induced HIF-1a activation preceded PI3K/Akt stimulation and was blocked by the DOR antagonist naltrindole and naloxone, pertussis toxin, different phosphoinositide 3-kinase (PI3K) inhibitors, and the Akt inhibitor Akti-1/2. Whereas DADLE exposure had no effect on the expression and secretion of vascular endothelial growth factor (VEGF) in BCa cells, an increased abundance of cyclooxygenase-2 (COX-2) and release of prostaglandin E2 (PGE 2) was detected. DADLE-induced COX-2 expression was also observed in three-dimensional cultured MCF-7 cells and impaired by PI3K/Akt inhibitors and the HIF-1a inhibitor echinomycin. Supernatant from DADLEtreated MCF-7 cells triggered sprouting of endothelial (END) cells, which was blocked when MCF-7 cells were pretreated with echinomycin or the COX-2 inhibitor celecoxib. Also no sprouting was observed when END cells were exposed to the PGE 2 receptor antagonist PF-04418948. The findings together indicate that DOR stimulation in BCa cells leads to PI3K/Aktdependent HIF-1a activation and COX-2 expression, which trigger END cell sprouting by paracrine activation of PGE 2 receptors. These findings provide a potential mechanism of opioid-driven tumor angiogenesis and thus therapeutic targets to combat the tumor-angiogenic opioid effect. SIGNIFICANCE STATEMENT Opioids are indispensable analgesics for treating cancer-related pain. However, opioids were found to promote tumor growth and metastasis, which questions the use of these potent painrelieving drugs in cancer patients. Enhanced tumor vascularization after opioid treatment implies that tumor progression results from angiogenic opioid effects. Thus, understanding the signaling mechanism of opioid-driven tumor angiogenesis helps to identify therapeutic targets to combat these undesired tumor effects. The present study reveals that stimulation of d-opioid receptors in breast cancer cells leads to an activation of HIF-1a and expression of COX-2 via PI3K/Akt stimulation, which results in a paracrine activation of vascular endothelial cells by prostaglandin E 2 receptors.

Combined exposure to high-cholesterol diet and PM 2.5 : Brain injury and regulatory mechanism of HIF-1α in female mice

“…COX-2 is a mediator of the in ammatory reaction in the CNS (Yagami et al, 2016). HIF-1α regulates COX-2; in turn, COX-2 mediates VEGF and MMP-9 (Schoos et al, 2019;Yang et al, 2020). VEGF, a downstream target gene of HIF-1α, was a predictor of an unfavorable outcome in stroke (Zhang et al, 2020).…”

Pancreatic Cancer and Microenvironments: Implications of Anesthesia

“…However, in the neuroglioma cell line, sevoflurane decreased HIF-1α expression via miR-210 , while desflurane downregulated HIF1-α and MMP-9 expressions via miR-138 and miR-335 , respectively [ 94 ]. Opioids were shown to promote tumor angiogenesis in a breast cancer cell by stimulation of δ-opioid receptors in breast cancer cells, leading to activation of HIF-1α and expression of COX-2 via PI3K/Akt stimulation [ 95 ]. However, Koodie et al reported that morphine suppressed tumor angiogenesis by inhibiting HIF-1α expression in mouse Lewis lung carcinoma cells [ 96 ].…”

Adoptive cell therapy of triple negative breast cancer with redirected cytokine-induced killer cells

“…In the presence of both a primary tumor in the fat pad and metastases in the lungs or lymph nodes, the lower portion of each animal was covered before reimaging, to ensure that the bioluminescence signals from the metastatic regions could be observed. Where indicated, the primary tumor was surgically excised from the fat pad 10 days after the injection, 14 and metastasis dissemination and growth in lymph nodes and lungs were monitored by bioluminescence.…”