Z Gastroenterol 2016; 54(12): 1343-1404
DOI: 10.1055/s-0036-1597455
4. Tumors/Liver Surgery
Georg Thieme Verlag KG Stuttgart · New York

Incomplete RFA causes cell cycle Arrest and enhanced tumor growth – in vitro and in vivo

PD Fazio
1   Philipps University Marburg, Department of Visceral and Thoracic Surgery, Marburg, Germany
,
S Gehring
2   Philipps University Marburg, Gastroenterology, Marburg, Germany
,
T Gress
2   Philipps University Marburg, Gastroenterology, Marburg, Germany
,
TT Wissniowski
2   Philipps University Marburg, Gastroenterology, Marburg, Germany
› Author Affiliations
Further Information

Publication History

Publication Date:
19 December 2016 (online)

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Background: Radiofrequency ablation (RFA) is a widely used palliative treatment option of small solid liver tumors. After RFA 3 areas can be histologically distinguished: total thermal necrosis, a hemorrhagic margin and a rim of sublethal damaged cells going into apoptosis.

If RFA is incomplete patients seem to suffer from enhanced tumor growth and spread.

The aim was to identify the clinical observable mechanism in vitro and in vivo.

HepG2 HCC cells were treated with RFA for 10 s, 20 s and 30 s in vitro. Cells were cultured for further experiments at standard conditions.

Cells were tested for apoptosis by DIOc6 and PI/Anexin staining. Chamber slides were stained for TUNEL reaction. Cell damage was assessd by luciferase assay for release of adenylate kinase into the supernatant.

Activity of caspases 3/7 and 8 were assessed by luciferase assay.

Nfkb activation was visualized by EMSA.

Bcl-2, BAX, and ER-stress markers BiP and CHOP were measured by RT-PCR and western blotting

Cell cycle was assessed by PI staining and flow cytometry.

20 NMRI mice were injected with 5 Mio. HepG2 cells s.c. and were randomized into 2 groups. Group 1 was left without further ttreatment while group 2 was treated with RFA with a power intake of 5 Ws into the tumor center.

30 days after treatment mice were autopsied and examined for tumor size, TUNEL and proliferation by PCNA

Results: In vitro 30 s RFA led to immediate necrosis. 20 s caused apoptosis and aponecrosis 4h after treatment.

10 s RFA caused in 9.7% cells apoptosis. Sublethal damaged cells showed S phase arrest.

Bcl-2 was significantly upregulated while pro apoptotic bax was significantly suppressed in vitro and in vivo as well.

Nfkb activation was only seen in cases treated with RFA.

Animals treated with 5 Ws RFA showed even an enhanced tumor progression compared to animals left without treament.

The Chaperon BiP was significantly upregulated after RFA in vitro while proapoptotic ER-stress related CHOP was not elevated after sublethal RFA in vitro and in vivo. Ther was no significant difference of BiP in vivo in both groups.

Discussion: Incomplete RFA causes S phase arrest and enhanced tumor growth by antiapoptotic bcl-2.

Bcl-2 and ER-stress could be therapeutic target for future multimodal aadjuvant therapies for local tumor ablation.