To investigate the effect and molecular mechanisms of action of Vitamin D3 (VD3) as a neo-adjunctive agent before cryosurgery in an effort to increase treatment efficacy for prostate cancer (CaP).
To eliminate the potential for disease recurrence that exists at the periphery of the freeze lesion, where temperatures may be insufficient to destroy both androgen-sensitive (AS) and androgen-insensitive (AI) CaP.
Human CaP cells, LNCaP, were each genetically altered to express the AS and AI phenotypes and subjected to VD3 treatment and freezing in an in vitro and tissue-engineered model.
Cell viability, caspase inhibitor and western blot studies were used to determine the basis of the different responses of AI and AS cells to VD3 cryosensitization.
VD3 was found to be a highly effective cryosensitizer, resulting in a >50% overall increase in cell death after -15°C freezing.
Fluorescence microscopy, western blot analysis and caspase protease assays confirmed that the increased activation of apoptosis was modulated through a mitochondrial-mediated pathway.
Caspase inhibition studies showed that apoptosis played an integral role in cell death, with VD3 cryosensitivation-induced apoptotic events responsible for > 30% of the overall cell death after -15°C freezing.
The present study suggests that the use of VD3 as a cryosensitizer increases cryoablation efficacy through the increased activity of apoptosis as well as through necrosis.
The data show that through VD3 treatment the overall level of AI CaP cell tolerance to freezing is reduced to a level similar to that of AS CaP.
VD3 pre-treatment in conjunction with cryoablation may increase treatment efficacy and reduce disease recurrence for CaP patients.