Purpose: Nuclear factor-nB (NF-nB)/REL transcription factors promote cancer cell survival and progression. The canonical (NF-nB1/RELA or cREL) and alternate (NF-nB2/RELB) pathways require the proteasome for cytoplasmic-nuclear translocation, prompting the investigation of bortezomib for cancer therapy. However, limited clinical activity of bortezomib has been observed in many epithelial malignancies, suggesting this could result from incomplete inhibition of NF-nB/ RELs or other prosurvival signal pathways. Experimental Design:To examine these possibilities, matched biopsies from 24 h posttreatment were obtained from accessible tumors of patients who received low-dose bortezomib (0.6 mg/m 2 ) before reirradiation in a phase I trial for recurrent head and neck squamous cell carcinoma (HNSCC). Effects of bortezomib on apoptosis and proliferation by TUNEL and Ki67 staining were compared with nuclear staining for all five NF-nB subunits, phosphorylated extracellular signal-regulated kinase 1/2 (ERK1/2), and phosphorylated signal transducers and activators of transcription 3 (STAT3) in tumor biopsies, and by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTP) and DNA binding assay for the five NF-nB subunits in HNSCC cell lines. Results: HNSCC showed increased nuclear staining for all five NF-nB subunits, phosphorylated ERK1/2, and phosphorylated STAT3. Bortezomib treatment significantly enhanced apoptosis with inhibition of nuclear RELA in three of four tumors, but other NF-nB subunits, ERK1/2, and STAT3 were variably or not affected, and tumor progression was observed within 3 months. In HNSCC cell lines, 10 -8 mol/L bortezomib inhibited cell density while inhibiting tumor necrosis factor-aî nduced and partially inhibiting basal activation of NF-nB1/RELA, but not NF-nB2/RELB. Conclusions: Although low-dose bortezomib inhibits activation of subunits of the canonical pathway, it does not block nuclear activation of the noncanonical NF-nB or other prosurvival signal pathways, which may contribute to the heterogeneous responses observed in HNSCC.Nuclear factor-nB (NF-nB) is an injury, pathogen, growth factor, cytokine, and matrix signal-inducible transcription factor that normally functions to regulate cell survival and proliferation and innate and adaptive immune responses (1). NF-nB transcription factors are heterodimers or homodimers composed from two families of REL proteins. Each member of the REL family contains an NH 2 terminal REL homology domain that mediates dimerization and domains mediating nuclear localization and binding to specific nB DNA sequence motifs in target genes (1). The first class, RELA (p65), RELB, and cREL, is synthesized in their mature forms, whereas the second class, consisting of NF-nB1(p105) and NF-nB2(p100), requires proteasome-dependent proteolysis of COOH terminal ankyrin repeats to yield p50 and p52, respectively (2). In the absence of activating stimuli, NF-nB dimers are also bound by a family of ankyrin repeat-containing inhibitor-nB (InB) proteins, sequeste...

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 signalregulated kinase 1/2, signal transducer and activator of transcription 3 (STAT3), and nuclear factor nB. 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-AKTand p-STAT3 could serve as potentially useful biomarkers and drug targets for further development of novel therapeutic agents for HNSCC.

Presenting stage, receptor status, pathologic response to neoadjuvant therapy, and omission the supraclavicular field were identified as risk factors for LRR after neoadjuvant therapy and PMRT.

Background: Aberrant activation of the nuclear factor kappaB (NF-κB) pathway has been previously implicated as a crucial signal promoting tumorigenesis. However, how NF-κB acts as a key regulatory node to modulate global gene expression, and contributes to the malignant heterogeneity of head and neck cancer, is not well understood.