Abstract 396: Effects of hypoxia on cell proliferation and lipidome profile in treatment-resistant prostate cancer cells
Authors: Siltari Aino , Välitalo Kalle , Laamanen Tomas , Tornberg Kaisa , Saarinen Alvar , Kreuzer Joose , Syvälä Heimo , Tammela Teuvo L. , Ilmonen Pauliina , Kallio Pasi , Murtola Teemu J. 
Published: March 2024

Abstract
Background: Low tissue content of oxygen i.e. hypoxia is typical in prostate cancer (PCa) tumor microenvironment. Hypoxia is also associated with PCa progression and treatment resistance. Modulation of lipid and cholesterol metabolism seems to be one way how tumor cells adapt to hypoxia. However, not much is known about lipidomic profiles in hypoxic condition in advanced PCa and treatment resistance. Aim: The aim of this study was to evaluate the impact of hypoxia on treatment-resistant PCa cells and investigate alterations in the lipidome under hypoxic conditions.
Material and Methods: Testosterone (T)-sensitive, T-independent (castration-resistant), and enzalutamide (enza)-resistant VCaP PCa cells were cultured for three days under hypoxia (1% O2) and compared with cells grown under normoxia (21% O2). Additionally, cells were treated with the drugs SREBP-inhibitor fatostatin and mevalonate-pathway inhibitor simvastatin to examine the effects of modulating lipid and cholesterol production on hypoxia responses. Relative cell growth by crystal violet staining and live/dead cell ratio were evaluated after each treatment. Intracellular lipidome was measured using liquid chromatography coupled with MS/MS method. Random forest classification was used of the selection of the lipids. Based on the classification, concentration differences between the groups were calculated.
Results: Growth of the T-sensitive and castration-resistant cells was decreased under hypoxia compared to normoxia. However, enza-resistant cells tolerated hypoxic conditions. Lipid-modifying drugs exhibited similar inhibitory effects on cell growth in both normoxia and hypoxia. Based on live/dead cell ratio, hypoxia induced cell death. Lipidome profiles varied markedly by oxygen content and cellular treatment resistance profile. Simvastatin treatment also influenced lipidome profiles.
Conclusions: Enza-resistant advanced PCa cells tolerated hypoxic conditions better compared to T-sensitive and T-independent cells. Lipidome was different between cell lines but also in hypoxia compared to normoxia, supporting its importance for PCa cells under varying conditions. Interference with lipid metabolism leads to growth inhibition regardless of hypoxia. These findings could be used in identifying potential markers for predicting or delaying disease progression in advanced PCa. Future studies should explore the efficacy of various lipidome-modulating drugs in delaying disease progression in PCa.
Citation Format: Aino Siltari, Kalle Välitalo, Tomas Laamanen, Kaisa Tornberg, Alvar Saarinen, Joose Kreuzer, Heimo Syvälä, Teuvo L. Tammela, Pauliina Ilmonen, Pasi Kallio, Teemu J. Murtola. Effects of hypoxia on cell proliferation and lipidome profile in treatment-resistant prostate cancer cells [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 396.