Abstract 3591: 15-Deoxy-Δ12,14-prostaglandin J2-induced epithelial-to-mesenchymal transition in human breast cancer cells promotes fibroblast activation

Abstract

Abstract In inflammation-associated carcinogenesis, cyclooxygenase-2 (COX-2) is markedly overexpressed, resulting in accumulation of various prostaglandins. 15-Deoxy-Δ12,14-prostaglandin J2 (15d-PGJ2) and prostahlandin E2 (PGE2) are the predominant COX-2-derived prostaglandins (PGs) with oncogenic potential. In the present study, we examined the effects of these to PGs on epithelial-to-mesenchymal transition (EMT), a process by which epithelial cells lose their cell polarity and cell-cell adhesion, and gain migratory and invasive properties. 15d-PGJ2 induced EMT to a greater than PGE2 in human breast cancer (MCF-7) cells. Snail and ZEB1 are known to bind to the E-boxes present in the E-cadherin promoter, thereby repressing E-cadherin transcription. Treatment of MCF-7 cells with 30 μM of 15d-PGJ2 increased the expression of Snail and ZEB1, followed by the down-regulation of E-cadherin. Nuclear extract from 15d-PGJ2-treated MCF-7 cells showed the binding of Snail and ZEB1 to E-box sequences in the E-cadherin promoter. In addition, among various cytokines/chemokines examined, the mRNA level of interleukin-8 (CXCL8) was highly elevated in 15d-PGJ2-stimulated MCF-7 cells. 15d-PGJ2-induced up-regulation of CXCL8 expression was abrogated by the introduction of Snail short interfering RNA. These findings suggest that CXCL8 may function as a positive regulator of EMT in 15d-PGJ2-treated MCF-7 cells. Moreover, the addition of conditioned medium of MCF-7 cells undergoing EMT activates normal fibroblast cells to cancer-associated fibroblasts (CAFs). Co-culture of normal fibroblasts with 15d-PGJ2-treaed-MCF-7 cells also induced the expression of α-SMA and FAPα, representative markers of CAFs. As a corresponding receptor of CXCL8, CXCR2 was overexpressed in activated fibroblasts co-cultured with 15d-PGJ2-treated MCF-7 cells. Unlike 15d-PGJ2, its non-electrophilic analogue 9,10-dihydro-15d-PGJ2 failed to induce EMT, suggesting that the α,β-unsaturated carbonyl group located in the cyclopentenone ring of 15d-PGJ2 is essential for EMT induction. Notably, activation of Rho kinase through direct binding of ArhGEF5, a guanine nucleotide exchange factor, with 15d-PGJ2 seems to contribute to the EMT induction. Taken together, above findings suggest that 15d-PGJ2 induces EMT through up-regulation of Snail expression and subsequent production of CXCL8 which may contribute to increased EMT of human breast cancer cells. Citation Format: Do-Hee Kim, Jeehye Choi, Jin-Young Suh, Hye-Kyung Na, Young-Joon Surh. 15-Deoxy-Δ12,14-prostaglandin J2-induced epithelial-to-mesenchymal transition in human breast cancer cells promotes fibroblast activation. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3591. doi:10.1158/1538-7445.AM2014-3591