105 Akt signaling mediates prostate cancer response to cryoablation

Abstract

Prostate cancer (CaP) has a significant impact on men’s health and quality of life with more than 230,000 new cases diagnosed annually in the United States. The androgen signaling pathway is integral in CaP progression and as such androgen deprivation is a widely utilized therapeutic option to treat CaP. Typically, with the application of the anti androgen treatment, the androgen sensitive (AS) CaP cells cease to proliferate and undergo apoptosis, leading to tumor regression. Although the therapy yields initial success in many cases, it eventually fails in most patients as the disease progresses to a hormone refractory state due to selection for androgen independent (AI) CaP. The mechanisms by which AI occurs are numerous, with many factors stimulating the mitogen-activated protein kinase or the Akt pathways, which may provide mechanisms for survival cross talk signaling. In AI cells, overabundant Akt signaling is one mechanism utilized to bypass reduced androgen responsiveness. As such, in this study, we investigated AKT signaling in two AI and two AS CaP cell lines following freezing in an effort to develop a more efficient therapeutic approach for CaP through the selective targeting of AKT signaling. Western blot analysis revealed total Akt levels for each cell line remained unchanged over the post-freeze analysis period. The AI LNCaP HP and PC-3 cells demonstrated an increased total Akt levels versus the AS LNCaP LP and PC-3 AR, respectively. This suggested that the AI cells had greater potential for Akt pathway signaling. In contrast to total Akt levels, phosphorylated Akt (pAkt) levels for AS cells declined substantially 3 to 6 h post-freeze. This suggests a reduction in cell survival signaling following the freezing event. Conversely, AI cells maintained elevated pAkt levels, indicating a strong cell survival signal following freezing. Modulation of AKT signaling using the Akt inhibitor Wortmannin, illustrated that Akt inhibition during freezing resulted in a reduction of post-freeze cell viability ( p Source of funding: CPSI Biotech. Conflict of interest: None declared. jmbaust@cpsibiotech.com