Cryoablative response of prostate cancer cells is influenced by androgen receptor expression

Abstract

OBJECTIVE To investigate in prostate cancer cells the consequences of androgen‐insensitivity (AI) development on the cellular and molecular responses to freezing, as a challenge in prostate cancer treatment occurs when the androgen‐sensitive (AS) phenotype switches to an AI phenotype, the latter of which is often refractory to many therapies. MATERIALS AND METHODS PC‐3 (AI) and LNCaP (AS) were each genetically altered to express the opposite phenotype and subjected to an in vitro freezing model. Viability, caspase inhibitor and Western blot studies were used to determine the basis of the differential responses of AI and AS cells. RESULTS LNCaP high‐passage cells, formed by repeated passage of LNCaP (AS) cells, were AI and showed a phenotypic shift to freeze resistance matching the freeze response of PC‐3 cells (AI). While stably transfected androgen receptor (AR)‐transfected cells (PC‐3 AR) had a freezing sensitivity similar to that of the LNCaP (AS) cell line. Importantly, AI cell lines survived and recovered from freezing exposure to temperatures as low as −40 °C whereas AS cell lines did not. Caspase inhibition studies and related fluorescent probes showed an elevated level of apoptotic involvement in both AS cell lines after freezing compared with their AI counterparts. Western blot analysis showed that AR expression was modified after exposure to freezing. CONCLUSION This study suggests that AS cancers may be far more sensitive to a freezing insult and this might be linked to elevated apoptosis and caspase activity. As such, cryoablation may prove most effective in cancer cells that have not yet progressed to a more resistant AI phenotype, but both generic variants can be fully ablated at sufficiently low temperatures.

Characterization of Pancreatic Cancer Cell Thermal Response to Heat Ablation or Cryoablation

“…37 Despite the approximately 50% cell death expressed following exposure to À15 C, these reports have shown that complete destruction of prostate cancer cells is not achieved until temperatures reach À40 C or below in vitro. [26][27][28]35,37 In regard to PaCa cells, in this study, we observed a moderate impact on the viability at À15 C or warmer, whereas temperatures below À20 C resulted in a more severe decrease in cell viability. Gage et al suggest that while temperatures within the range of À20…”

“…Fluorescence microscopy indicated that the different cells subjected to the same exposures experienced varying levels of cell death at different points within the initial 24 hours postexposure ( Figure 3). These results indicate that, as with other cancers, [25][26]35 PaCa molecular variants exhibit differential responses to mild thermal treatment. However, these data suggest that when a critical temperature threshold is surpassed (<À25 C or >50 C), complete cell death results regardless of the molecular disposition.…”

“…While À40 C or 60 C isotherms serve as a reference point, the critical lethal temperature for PaCa has yet to be reported. In addition, given reports of varying sensitivity of different molecular variants of similar cancers by Klossner et al 35 and others, we also investigated 2 distinct molecular phenotypes of PaCa, PANC-1 and BxPC-3 cells.…”

Minimizing cryopreservation-induced loss of disc cell activity for storage of whole intervertebral discs

“…Slow permeation of CPA in cornea and cartilage has been reported, possibly due to the presence of highly charged GAG (Klossner et al, 2008) and collagenous network (Maroudas, 1976;Walcerz et al, 1995). The IVD being a GAG-and collagen-rich tissue (Roberts and Caterson, 2004), might behave similarly with slow CPA permeation.…”

Biophysiologic considerations in cryoablation: a practical mechanistic molecular review

“…Baust et al examined survival rates of in vitro prostate and colorectal cancer cell lines after a single cycle of cryoablation and found an increased cell survival rate when the cells were exposed to caspase inhibitors (12). Another study by Klossner et al demonstrated that androgen insensitive prostate cancer cell lines showed significantly increased survival rates versus androgen sensitive cell lines after treatment (13). There are, however, also encouraging indications that adjuvant therapies may increase tumor sensitivity to cryotherapy.…”