BAT1 Alters Migration, Invasion and Pro‐Inflammatory Cytokines in Prostate Cancer

Abstract

Prostate cancer (PCa) is the most frequently diagnosed non‐cutaneous cancer and the second cause of cancer related deaths in men. Though PCa is often treated with radical prostatectomy and radiation therapy, 15%–30% of patients may undergo biochemical recurrence. The current biomarkers are inadequate to identify recurrence, thus there is a demand for the development of biomarkers that can identify recurrence. In preliminary data, HLA‐B associated transcript 1 (BAT1) was down‐regulated in patients with PCa recurrence when compared with non‐recurrent PCa patients. BAT1 has been identified as an anti‐inflammatory gene in other types of diseases. The role of BAT1 in PCa has not been identified. We hypothesize that BAT1 expression will affect cell migration, invasion, and inflammatory cytokine expression in vitro and in vivo. Our objective was to identify the role of BAT1 expression in PCa. We down‐regulated and upregulated BAT1 in androgen independent PC3 and androgen dependent 22RV1 prostate cancer cell lines using BAT1 small‐interfering RNA (siRNA) and complementary DNA (cDNA) lentiviral particle infections, respectively. In vitro assays were performed to measure BAT1 protein expression, migration, invasion and gene expression in prostate cancer cells. Western blot analysis showed that BAT1 protein expression was significantly down‐regulated in PC3 and 22RV1 siRNA transfected cells and overexpressed in PC3 and 22RV1 cDNA infected cells when compared to control. BAT1 down‐regulation significantly increased cell migration and invasion when compared to control. In contrast, BAT1 overexpression significantly decreased cell migration and invasion when compared to control. Real time PCR (RT‐PCR) showed changes in expression of pro‐inflammatory cytokines (TNF‐α and IL‐6) and genes that regulate cell adhesion and migration (MMP10, MMP13 and TIMPs) in BAT1 overexpressed cells when compared to BAT1 siRNA cells. In vivo studies were performed using severe combined immunodeficient (SCID) orthotopic mice injected with 22RV1 cells previously transfected with BAT1 short hairpin ribonucleic acid (shRNA) or BAT1 cDNA. The cells were injected directly into the prostate and allowed to form tumors for analysis. Immunohistochemistry analysis showed increases in the expression of TNF‐α, IL‐6 and MMP10 in tumors developed from BAT1 shRNA treated mice when compared to tumors developed from BAT1 cDNA treated mice. These results suggest that BAT1 expression alters inflammation through the modulation of TNF‐α and IL‐6 expression and can eventually promote migration and invasion through the expression of MMPs and TIMPs.Support or Funding InformationThis work is supported by the NIGMS‐RISE Program #R25GM061838