Journal
MOLECULAR CANCER
Volume 6, Issue -, Pages -Publisher
BMC
DOI: 10.1186/1476-4598-6-63
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Funding
- NCI NIH HHS [P30 CA016672, P30 CA16672] Funding Source: Medline
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Background: Searching for novel molecular markers that dependably predict or indicate responses of human cancer cells to epidermal growth factor receptor (EGFR)-targeted therapy is strongly warranted. The purpose of the current study was to evaluate hypoxia-inducible factor-1 alpha (HIF-1 alpha) as a novel response marker compared with previously explored markers following treatment with an EGFR-blocking monoclonal antibody (cetuximab) and a small-molecule EGFR tyrosine kinase inhibitor (gefitinib) in a group of cancer cell lines containing wild-type or tyrosine kinase domain-mutated EGFR. Results: We found that, compared with previously studied response markers, including EGFR per se and three EGFR downstream signal molecules (ERK, Akt, and STAT3), which showed variable post- treatment changes in levels of phosphorylation and no consistent link of the changes to therapeutic responses, HIF-1 alpha showed a selective decrease in protein levels only in responsive cell lines. To demonstrate a critical role of HIF-1 alpha downregulation by EGFR-targeted treatment, we introduced a constitutively expressed HIF-1 alpha mutant (HIF-1 alpha/Delta ODD) that is resistant to cetuximab-induced downregulation in a cetuximab-responsive cell line (A431); we found that the HIF-1 alpha/Delta ODD-transfected cells remained sensitive to cetuximab-induced inhibition of Akt and ERK phosphorylation but were remarkably less responsive to cetuximab-induced growth inhibition compared with corresponding control cells. Conclusion: Our data indicates that downregulation of HIF-1 alpha is associated with positive therapeutic responses of cancer cells to EGFR-targeted therapy and suggest further investigation using HIF-1 alpha as an indicator of tumor response to EGFR-targeted therapy in preclinical studies and in the clinical setting.
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