NF-kappaB kinetics predetermine TNF-alpha sensitivity of colorectal cancer cells.
BACKGROUND
Tumour necrosis factor (TNF)-alpha has considerable anti-tumour activity and may have potential as a treatment for metastatic colorectal cancer. However, TNF-alpha responses in patients and cell lines are variable and TNF-alpha treatment is associated with dose limiting clinical toxicity. Activation of NF-kappaB is protective against TNF-alpha induced cell death, and this may explain tumour resistance.


METHODS
In order to provide further understanding of determinants of TNF-alpha responses, we studied TNF-alpha induced NF-kappaB activation and variable tumour responses. We analysed the kinetics of TNF-alpha induced NF-kappaB activation in colorectal cancer cells and determined whether it is possible to sensitize colorectal tumour cells to TNF-alpha by modulation of NF-kappaB signalling.


RESULTS
We demonstrated that sustained NF-kappaB activation exceeding 16 h was observed in HRT18 and SW480 cells and was associated with TNF-alpha resistance. In contrast, transient NF-kappaB activation in HCT116 cells was associated with sensitivity to cytotoxic TNF-alpha effects, suggesting that NF-kappaB kinetics may have utility as clinical marker of TNF-alpha tumour resistance. Despite variable TNF-alpha responses and NF-kappaB kinetics, all three colorectal cancer cell lines were highly sensitive to treatment with the TNF-related apoptosis-inducing ligand (TRAIL) which induced only transient NF-kappaB activation. This further supports the notion of a pre-determined NF-kappaB response influencing receptor-mediated cell death. We also show that stable transfection and adenoviral-mediated expression of IkappaB(A32/36) can be used to confer TNF-alpha sensitivity to colorectal tumour cells previously resistant.


CONCLUSIONS
These findings indicate that a combined approach using gene therapy and recombinant TNF-alpha merits further appraisal. Furthermore, the kinetics of the TNF-alpha response could be determined using a 'test-dose' to indicate whether individual patients might benefit from this gene therapy approach.
Zwacka
R M
RM
Department of Oncology, University of Edinburgh, UK. Ralf.Zwacka@hgu.mrc.ac.uk
Stark
L
L
Dunlop
M G
MG
D000256:Adenoviridae / Q000235:genetics; D017209:Apoptosis / Q000187:drug effects; D051017:Apoptosis Regulatory Proteins; D015179:Colorectal Neoplasms / Q000188:drug therapy* / Q000378:metabolism* / Q000628:therapy; D004268:DNA-Binding Proteins / Q000235:genetics; D004351:Drug Resistance; D015870:Gene Expression; D015316:Genetic Therapy; D006801:Humans; D020672:I-kappa B Proteins; D007700:Kinetics; D008562:Membrane Glycoproteins / Q000378:metabolism; D000072000:NF-KappaB Inhibitor alpha; D016328:NF-kappa B / Q000378:metabolism*; D053221:TNF-Related Apoptosis-Inducing Ligand; D014162:Transfection; D014407:Tumor Cells, Cultured; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism / Q000494:pharmacology*
D051017:Apoptosis Regulatory Proteins; D004268:DNA-Binding Proteins; D020672:I-kappa B Proteins; D008562:Membrane Glycoproteins; D016328:NF-kappa B; C000606204:NFKBIA protein, human; D053221:TNF-Related Apoptosis-Inducing Ligand; C505653:TNFSF10 protein, human; D014409:Tumor Necrosis Factor-alpha; D000072000:NF-KappaB Inhibitor alpha