Tempol Treatment Inhibits Inflammatory Process and Improves Morphological Aspects in Early and Late‐stage of Prostate Cancer Progression in the Ventral Lobe of TRAMP Model.

Abstract

Tempol (4‐hydroxy‐TEMPO) is a SOD mimetic and member of the nitroxide compounds family. It is used as a co‐adjuvant or protective factor in cancer treatment due to its anti‐oxidant properties. However, in prostate cancer (PCa) Tempol effects are still poorly understood. Its known that PCa progression requires a sustained inflammation, which generates a broad spectrum of reactive nitrogen and oxygen species, leading to uncontrolled cellular proliferation. We aimed to evaluate the Tempol effects in different stages of PCa progression (a) in vivo using a transgenic adenocarcinoma of the mouse prostate model (TRAMP); (b) and in vitro using human PCa cell lines with different genetic background. For the early‐stage analysis, 8‐weeks‐old mice (TPL1 group) were treated orally with 50 mg/kg of Tempol during 4 weeks. For the late‐stage analysis, 16‐weeks‐old mice were treated with 50mg/Kg (TPL2 group) or 100mg/Kg (TPL3 group) of Tempol during the same period. All control groups received water as vehicle. The ventral lobe of the prostate was collected and submitted to the histopathological, immunohistochemical and Western blotting analysis. PC‐3 and LnCaP cells were exposed to different doses of Tempol (0.5, 1.0 and 2.0 mM) and cell viability assay was performed. In vivo, Tempol treatment promoted a great improvement in the prostatic epithelium in all the analyzed cancer stages, reducing significantly premalignant (high‐grade prostatic intraepithelial neoplasia) and malignant lesions (well differentiated prostatic adenocarcinoma). The PCNA immunostaining confirmed the cellular proliferation decrease between the control and treated groups. Tempol also reduced COX‐2 and NFkB, especially in the early‐stage, whereas iNOS increased in this period. In the late‐stage, both doses of Tempol reduced NFkB levels concomitant with IkB‐α increase, suggesting an inhibitory effect of Tempol on NFkB pathway in association with its anti‐oxidant role. In vitro, Tempol decreased cell viability of both cell lines, being the 1.0 mM dose the most efficient and nontoxic concentration. In conclusion, Tempol had a remarkable action in the prostate, delaying cancer progression in the ventral lobe of TRAMP model and inhibiting PC‐3 and LnCaP growth. This SOD mimetic presented great capability of inhibiting the inflammation process, and consequently the cell proliferation. Its action was effective in different stages of PCa progression, particularly in the early stage, indicating that Tempol treatment can be explored as a preventive approach. Finally, for the late PCa stage, Tempol may be considered as an interesting adjuvant therapy.Support or Funding InformationSão Paulo Research Foundation, FAPESP, process 2018/21647‐6 and FAEPEX/UNICAMP, process 2202/19