Tempol differential effect on prostate cancer inflammation: In vitro and in vivo evaluation

Tempol is a redox-cycling nitroxide that acts directly on inflammation. However, few studies have reported the use of tempol in prostate cancer (PCa). The present study investigated the effects of tempol on inflammation related to NF-κB signaling, using hormone-dependent or hormone-independent cell lines and the transgenic adenocarcinoma of the mouse prostate PCa animal model in the early and late stages of cancer progression.

PC-3 and LnCaP cells were exposed to different tempol doses in vitro, and cell viability assays were performed. The optimal treatment dose was chosen for subsequent analysis using western blotting. Five experimental groups were evaluated in vivo to test for tempol effects in the early (CT12 and TPL12 groups) and late stages (CT20, TPL20-I, and TLP20-II) of PCa development. The TPL groups were treated with 50 or 100 mg/kg tempol. All control groups received water as the vehicle. The ventral lobe of the prostate was collected and subjected to immunohistochemical and western blot analysis.

Tempol treatment reduced cellular proliferation in vitro and improved prostatic morphology in vivo, thereby decreasing tumor progression. Tempol reduced inflammation in preclinical models, and downregulated the initial inflammatory signaling through toll-like receptors, not always mediated by the MyD88 pathway. In addition, it upregulated iκB-α and iκB -β levels, leading to a decrease in NF-κB, TNF-α, and other inflammatory markers. Tempol also influenced cell survival markers.

Tempol can be considered a beneficial therapy for PCa treatment owing to its anti-inflammatory and antiproliferative effects. Nevertheless, the action of tempol was different depending on the degree of the prostatic lesion in vivo and hormone reliance in vitro. This indicates that tempol plays a multifaceted role in the prostatic tissue environment.