ABSTRACT
PURPOSE: Gefitinib targeting of the epidermal growth factor receptor (EGFR) has shown limited activity in clinical trials of head and neck squamous cell carcinoma (HNSCC). To investigate the underlying molecular mechanism, the proteomic signatures and responses of EGFR and downstream signals have been studied in a panel of HNSCC cell lines and tumor specimens pre- and post-gefitinib treatment. EXPERIMENTAL DESIGN: The IC(50) of gefitinib for HNSCC cell lines were determined using 3-(4,5-dmethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide proliferation assay. The effects of gefitinib on activation of EGFR and downstream signaling molecules were determined by Western blot, ELISA, and reverse-phase protein microarray (RPMA). The biomarkers involved in the signaling pathways were examined in HNSCC tumor specimens from patients in a phase I gefitinib trial. RESULTS: In vitro, gefitinib inhibited cell proliferation with differing IC(50), and suppressed activation of EGFR and downstream signaling molecules protein kinase B (AKT), extracellular signal-regulated kinase 1/2, signal transducer and activator of transcription 3 (STAT3), and nuclear factor kappaB. The drug sensitivity was statistically correlated with activation of phosphorylated AKT (p-AKT) and phosphorylated STAT3 (p-STAT3) detected by ELISA, and consistent with results measured by RPMA. In patient samples, a broad suppression of activation of EGFR and downstream signaling molecules was observed in a molecular responder patient, in contrast to a lack of inhibition or increased activation of biomarkers in different pathways in nonresponder patients. CONCLUSIONS: Gefitinib sensitivity is correlated with p-AKT and p-STAT3 activation in HNSCC cell lines and tumor specimens. p-AKT and p-STAT3 could serve as potentially useful biomarkers and drug targets for further development of novel therapeutic agents for HNSCC.
Subject(s)
Antineoplastic Agents/pharmacology , Carcinoma, Squamous Cell/metabolism , ErbB Receptors/antagonists & inhibitors , Head and Neck Neoplasms/metabolism , Protein Kinase Inhibitors/pharmacology , Quinazolines/pharmacology , Signal Transduction/drug effects , Antineoplastic Agents/therapeutic use , Biomarkers, Tumor/analysis , Blotting, Western , Carcinoma, Squamous Cell/drug therapy , Carcinoma, Squamous Cell/enzymology , Cell Line, Tumor , Cell Survival/drug effects , Clinical Trials, Phase I as Topic , Enzyme-Linked Immunosorbent Assay , Epidermal Growth Factor/antagonists & inhibitors , ErbB Receptors/metabolism , Gefitinib , Head and Neck Neoplasms/drug therapy , Head and Neck Neoplasms/enzymology , Humans , Inhibitory Concentration 50 , NF-kappa B/antagonists & inhibitors , Phosphorylation , Protein Array Analysis , Protein Kinase Inhibitors/therapeutic use , Proteomics , Quinazolines/therapeutic useABSTRACT
Follicular lymphoma (FL) is characterized by constitutive expression of Bcl-2 as a consequence of t(14;18). Evidence suggests factors in the lymph node microenvironment, related to intratumoral T cells, macrophages, and dendritic cells, play a role in the disease process. We generated proteomic cytokine profiles of FL (N = 50) and follicular hyperplasia (FH; N = 23). A total of 10 cytokines were assayed using ultrasensitive multiplex enzyme-linked immunosorbent assays: IL-1beta, IL-2, IL-4, IL-5, IL-8, IL-10, IL-13, IL-12p70, tumor necrosis factor-alpha, and interferon-gamma. Each cytokine showed overall lower protein concentrations in FL, with the exception of IL-4, which was nearly 5 times higher in FL than FH (P = .005). Using reverse-phase protein microarrays (RPMAs), we evaluated the activation state of several intracellular signaling proteins downstream of cytokine receptors. Basal Erk phosphorylation was approximately 4 times greater in FL than FH (P < .001), with similar findings for Mek; Stat-6 showed weak basal phosphorylation that was approximately twice as high in FL than in FH (P = .012). In conclusion, the FL microenvironment contains increased levels of IL-4, with prominent tumor basal phosphorylation of Erk. These findings suggest IL-4, Erk, and possibly Stat-6 may play a role in the biology of FL and may serve as targets for future therapies.
Subject(s)
Interleukin-4/metabolism , Lymphoma, Follicular/metabolism , Mitogen-Activated Protein Kinases/metabolism , Adult , Aged , Cytokines/metabolism , Enzyme Activation , Female , Humans , Male , Middle Aged , Protein Array Analysis , Pseudolymphoma/metabolism , STAT6 Transcription Factor/metabolismABSTRACT
Application of novel technology to clinical samples requires optimization of procedures. Reverse phase protein lysate arrays use femtomolar quantities of tissue lysate from clinical samples with which to profile biochemical events happening in the tumor. We analyzed the effects of different tissue solubilization buffers on frozen ovarian tumor samples in order to identify the system with the best signal intensity dynamic range, reproducibility, tissue solubility, and signal consistency. A modified RIPA-like buffer supplemented with DTT and SDS was deemed optimal.
