Heat stress induced cell death mechanisms in hepatocytes and hepatocellular carcinoma: In vitro and in vivo study. Issue 4 (18th March 2014)

• Record Type: Journal Article
• Authors: Thompson, Scott M.; Callstrom, Matthew R.; Butters, Kim A.; Knudsen, Bruce; Grande, Joseph P.; Roberts, Lewis R.; Woodrum, David A.
• Is Part Of: Lasers in surgery and medicine. Volume 46:Issue 4(2014)
• Page Start: 290
• Page End: 301
• Publication Date: 2014-03-18
• Subjects: Lasers in medicine -- Periodicals; Lasers in surgery -- Periodicals; 617
• DOI: 10.1002/lsm.22231
• Languages: English
• ISSNs: 0196-8092

Abstract

<abstract abstract-type="main" xml:lang="en"> <title>ABSTRACT</title> <sec id="lsm22231-sec-0001" sec-type="section"> <title>Background and Objective</title> <p>The aims of the present study were to investigate the thermal‐dose dependent effect of heat stress on hepatocyte and HCC cell death mechanisms using clinically relevant experimental heat stress conditions <italic>in vitro</italic> and to investigate apoptotic cell death induced by laser thermal ablation <italic>in vivo</italic>.</p> </sec> <sec id="lsm22231-sec-0002" sec-type="section"> <title>Study Design/Materials and Methods</title> <p>Institutional Animal Care and Use Committee approved all studies. Hepatocyte and HCC cell lines were heat stressed from 37 to 60°C for 2 or 10 minutes and assessed for viability, cytotoxicity and caspase‐3/7 activity at 6 and/or 24 hours post‐treatment (<italic>N</italic> = 3). Viability experiments were repeated with the RIPK1 inhibitor Necrostatin‐1 to block necroptosis (<italic>N</italic> = 3). Rats with orthotopic HCC tumors stably expressing luciferase (N1S1<italic>luc2</italic>) were randomized to US‐guided laser ablation (3W‐45s for an intentional partial ablation; <italic>N</italic> = 6) or sham (<italic>N</italic> = 6) and followed by post‐ablation caspase‐3/7 bioluminescence imaging at 6 and 24 hours and cleaved caspase‐3 immunostaining. <italic>P</italic> < 0.05 was considered statistically significant.</p> </sec> <sec id="lsm22231-sec-0003" sec-type="section"> <title>Results</title> <p>Heat‐stress induced apoptosis and necrosis in hepatocytes and HCC cells in a thermal dose and cell‐type dependent manner. Inhibition of RIPIK1‐mediated necroptosis induced a significant, differential increase in HCC cell viability under physiologic and hyperthermic heat stress (<italic>P</italic> < 0.001). Intentional partial laser thermal ablation induced a significant increase in caspase‐3/7 activity in the laser versus sham ablation groups at both 6 hours (10.1‐fold, <italic>P</italic> < 0.01) and 24 hours (16.7‐fold, <italic>P</italic> < 0.02). Immunohistochemistry confirmed increased cleaved caspase‐3 staining at the tumor ablation margin 24 hours post‐ablation.</p> </sec> <sec id="lsm22231-sec-0004" sec-type="section"> <title>Conclusions</title> <p>Both regulated and non‐regulated cell death mechanisms mediate heat stress‐induced HCC cell killing and vary between hepatocytes and HCC subtypes. Apoptosis is a significant mechanism of cell death at the HCC tumor ablation margin. Lasers Surg. Med. 46:290–301, 2014. © 2014 Wiley Periodicals, Inc.</p> </sec> </abstract>