Abstract 1487: Dysregulation of Interleukin-1 receptor-associated kinase 1 promotes prostate cancer-associated chronic inflammation and aggressiveness

For decades, chronic inflammation has been linked with cancer development. However, the molecular mechanisms of this association with respect to prostate cancer (PCa) aggressiveness are poorly understood. While previous studies exploiting the contributions of upstream and downstream inflammation signaling proteins to this oncogenic alliance have been clinically unsuccessful, the goal of our study is to elucidate the role of the often-neglected midstream inflammation regulatory proteins, such as the Interleukin-1 receptor-associated kinase 1 (IRAK1). We propose that the dysregulation of IRAK1 protein will promote PCa-associated chronic inflammation and aggressiveness. To explore the importance of IRAK1 in PCa-associated chronic inflammation and aggressiveness, both bioinformatics and experimental approaches were employed. Cutting-edge computational meta-analysis was used to characterize and assess the molecular patterns of gene expression and alteration of IRAK1 in clinical datasets of PCa patients acquired from open resource databases. Inflammation-associated PCa models were established by pre-exposure of aggressive PC3-CRPC cells to low doses (10ng-10µg/ml) of TLR-2, -3, -4 and -7/8 agonists, such as zymosan, poly (I:C), LPS, and resiquimod, respectively, which led to the upregulation of IRAK1 prior to mechanistic studies. Chronic inflammation was confirmed by measuring changes in the levels of IL-6/IL-12 via ELISA. IRAK1 mRNA and protein upregulation were analyzed by RT-PCR and western blot or immunofluorescent staining. Next, we investigated the effects of IRAK1 dysregulation on the aggressiveness of PCa cells by downregulating IRAK1 expression in PC3 cells by either pharmacologic inhibition with thymoquinone (an IRAK1 inhibitor) or via RNAi. MTT and colony forming assays were performed to assess the effects on cell viability and survival. IRAK1 mRNA and protein levels in PC3 cells following treatment with thymoquinone or IRAK1 inhibitor were measured using RT-PCR, western blot or immunocytochemistry. Cell migration was assessed by wound healing assay. Acridine orange/propidium iodide fluorescent staining and flow cytometry were used to analyze the effect on cell cycle and apoptosis. Our computational analysis shows that IRAK1 is commonly upregulated at the mRNA and protein levels and genetically altered/mutated in clinical PCa samples. Downregulation of IRAK1 by thymoquinone or RNAi in PC3 cells result in a decrease in cell viability, cell migration, and proinflammatory cytokines as well as an increase in apoptotic cell death in a dose and time-dependent manner. Upregulation of IRAK1 prior to treatment with PI3K/AKT/mTOR pathway inhibitors abrogates the anticancer effects of these drugs. Our study establishes IRAK1 as a promising therapeutic target to treat PCa-associated chronic inflammation and aggressiveness. Citation Format: Saheed Oluwasina Oseni, Cynthia Nguyen, Mirjana Pavlovic, James Kumi-Diaka. Dysregulation of Interleukin-1 receptor-associated kinase 1 promotes prostate cancer-associated chronic inflammation and aggressiveness [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2019; 2019 Mar 29-Apr 3; Atlanta, GA. Philadelphia (PA): AACR; Cancer Res 2019;79(13 Suppl):Abstract nr 1487.