Effect of tumour necrosis factor-α and irradiation alone or in combination on the viability of hepatocellular and biliary adenocarcinoma cell lines in vitro

Background: Tumour necrosis factor α (TNF-α) may exhibit antitumoral activity and can influence the reaction of both tumour and normal tissue to radiation. Aims: To test the effect of TNF-α and/or irradiation on hepatocellular (HepG2, Hep3B, Sk-Hep1, HuH7) and cholangiocellular (Sk-chA1, Mz-chA1) tumour cell lines. Methods: Colony formation, apoptosis analysis and trypan blue exclusion were used to assess cell viability. Doses of radiation (2–25 Gy) and TNF-α (100–50 000 U) as well as their respective sequencing were varied (24 and 12 h before and 6 h after). The expression of TNF-α and TNF receptors 1/2 was determined using real-time polymerase chain reaction and IκBα protein expression was detected by Western blot. Results: Sole irradiation induced a reduction in colony formation in all cell lines and sole TNF-α in HepG2 and Sk-chA1 cells only. No difference in apoptosis induction after TNF-α or irradiation was observed. Cellular death induced by the combination of TNF-α and radiation was not superior to the use of any of the two agents alone. All cell lines revealed that radiation induced upregulation of TNF-α whereas the extent of TNF receptor-specific transcription did not change. Furthermore, radiation-induced changes in IκBα expression were not detectable. Conclusions: Our data suggest that both TNF-α and radiation may be treatment options for hepatocellular and cholangiocellular carcinomas. Because TNF-α and radiation do not interact in terms of radiosensitization, anti-TNF-α treatment may have the potential to protect against hepatocellular injury after abdominal irradiation. However, further in vivo studies are needed to confirm that anti-TNF-α treatment does not compromise tumour control and actually attenuates radiation-induced liver injury.