MAPK pathway mutations in head and neck cancer affect immune microenvironments and ErbB3 signaling.

MAPK pathway mutations affect one-fifth of head and neck squamous cell carcinoma (HNSCC). Unexpectedly, MAPK pathway aberrations are associated with remarkably long patient survival, even among patients with TP53 mutations (median ∼14 yr). We explored underlying outcome-favoring mechanisms with omics followed by preclinical models. Strikingly, multiple hotspot and non-hotspot MAPK mutations (A/BRAF, HRAS, MAPK1, and MAP2K1/2) all abrogated ErbB3 activation, a well-established HNSCC progression signal. Inhibitor studies functionally defined ERK activity negatively regulating phospho-ErbB3 in MAPK-mutants. Furthermore, pan-pathway immunoprofiling investigations identified MAPK-mutant tumors as the only "CD8+ T-cell-inflamed" tumors inherently bearing high-immunoreactive, constitutive cytolytic tumor microenvironments. Immunocompetent MAPK-mutant HNSCC models displayed active cell death and massive CD8+ T-cell recruitment in situ. Consistent with CD8+ T-inflamed phenotypes, MAPK-mutant HNSCC patients, independent of tumor-mutational burden, survived 3.3-4 times longer than WT patients with anti-PD1/PD-L1 immunotherapies. Similar prognosticity was noted in pan-cancers. We uncovered clinical, signaling, and immunological uniqueness of MAPK-mutant HNSCC with potential biomarker utilities predicting favorable patient survival.

The degree of intratumor mutational heterogeneity varies by primary tumor sub-site.

In an era where mutational profiles inform treatment options, it is critical to know the extent to which tumor biopsies represent the molecular profile of the primary and metastatic tumor. Head and neck squamous cell carcinoma (HNSCC) arise primarily in the mucosal lining of oral cavity and oropharynx. Despite aggressive therapy the 5-year survival rate is at 50%. The primary objective of this study is to characterize the degree of intratumor mutational heterogeneity in HNSCC. We used multi-region sequencing of paired primary and metastatic tumor DNA of 24 spatially distinct samples from seven patients with HNSCC of larynx, floor of the mouth (FOM) or oral tongue. Full length, in-depth sequencing of 202 genes implicated in cancer was carried out. Larynx and FOM tumors had more than 69.2% unique SNVs between the paired primary and metastatic lesions. In contrast, the oral tongue HNSCC had only 33.3% unique SNVs across multiple sites. In addition, HNSCC of the oral tongue had fewer mutations than larynx and FOM tumors. These findings were validated on the Affymetrix whole genome 6.0 array platform and were consistent with data from The Cancer Genome Atlas (TCGA). This is the first report demonstrating differences in mutational heterogeneity varying by subsite in HNSCC. The heterogeneity within laryngeal tumor specimens may lead to an underestimation of the genetic abnormalities within tumors and may foster resistance to standard treatment protocols. These findings are relevant to investigators and clinicians developing personalized cancer treatments based on identification of specific mutations in tumor biopsies.

Primary chemotherapy and radiation as a treatment strategy for HPV-positive oropharyngeal cancer.

The incidence of human papillomavirus-positive oropharyngeal cancer (HPV/OPSCC) is rapidly increasing, which will represent a major public health burden for decades to come. Although HPV/OPSCC is generally associated with a better prognosis than HPV-negative OPSCC, the survival rate of individuals with higher-risk clinical and pathologic features remains unchanged. Emerging evidence suggests that HPV/OPSCC is pathologically and molecularly distinct from HPV-negative OPSCC. This review focuses on summarizing treatment strategies for HPV/OPSCC by reviewing the peer-reviewed literature and noting ongoing and planned clinical trials in this disease. We also discuss the potential of designing targeted therapy based on the recent genomic findings of HPV/OPSCC.

New advances in molecular approaches to head and neck squamous cell carcinoma.

Head and neck squamous cell cancer is the sixth most common cancer in the world. Despite advances in combined modality therapy, poor outcomes continue to be observed in the form of locoregional recurrence, metastasis, and development of second primary tumors. As tumors vary in their molecular and genetic etiology and because often there is already deregulation at the molecular level in otherwise histopathologically normal tissue, risk stratification using clinical and pathologic criteria alone has proved to be inadequate. In this article, the reader will gain an appreciation for the current advances in biomarker discovery using advanced technology and data interpretation in microarray analysis and proteomics. In addition, other molecular targets, aside from epidermal growth factor receptor, are discussed in the context of their promising role in predicting recurrence, response to therapy, survival, and overall prognosis.

Cross-talk between estrogen receptor and epidermal growth factor receptor in head and neck squamous cell carcinoma.

PURPOSE: This study aimed to characterize estrogen receptor expression and signaling in head and neck squamous cell carcinoma (HNSCC) cell lines and patient tissues, and to evaluate estrogen receptor and epidermal growth factor (EGF) receptor (EGFR) cross-activation in HNSCC. EXPERIMENTAL DESIGN: Estrogen receptor expression and signaling in HNSCC cell lines were assessed by immunoblotting. In vitro proliferation and invasion were evaluated in HNSCC cell lines in response to estrogen receptor and EGFR ligands or inhibitors. Estrogen receptor and EGFR protein expression in patient tissues was assessed by immunohistochemical staining. RESULTS: Phospho-mitogen-activated protein kinase (P-MAPK) levels were significantly increased following combined estrogen and EGF treatment. Treatment of HNSCC cells with estrogen and EGF significantly increased cell invasion compared with either treatment alone, whereas inhibiting these two pathways resulted in reduced invasion compared with inhibiting either pathway alone. EGFR (P = 0.008) and nuclear estrogen receptor alpha (ER alpha(nuc); P < 0.001) levels were significantly increased in HNSCC tumors (n = 56) compared with adjacent mucosa (n = 30), whereas nuclear estrogen receptor beta (ER beta(nuc)) levels did not differ (P = 0.67). Patients with high ER alpha(nuc) and EGFR tumor levels had significantly reduced progression-free survival compared with patients with low tumor ER alpha(nuc) and EGFR levels (hazards ratio, 4.09; P = 0.01; Cox proportional hazards). In contrast, high ER beta(nuc) tumor levels were not associated with reduced progression-free survival alone or when combined with EGFR. CONCLUSIONS: ER alpha and ER beta were expressed in HNSCC, and stimulation with estrogen receptor ligands resulted in both cytoplasmic signal transduction and transcriptional activation. Estrogen receptor and EGFR cross-talk was observed. Collectively, these studies indicate that estrogen receptor and EGFR together may contribute to HNSCC development and disease progression.

The current state of head and neck cancer gene therapy.

The incidence of head and neck cancer continues to increase worldwide, with tobacco exposure and human papillomavirus type 16 infections being the major etiological factors. Current therapeutic options are ineffective in approximately half of the individuals afflicted with this malignancy. Developments in the identification of molecules that sustain head and neck squamous cell carcinoma (HNSCC) growth and survival have made molecular targeting by gene therapy approaches a feasible therapeutic strategy. Although gene therapy was originally designed to correct single gene defects, it has now evolved to encompass all forms of therapeutic interventions involving engineered cells and nucleic acids that modify the overall pattern of gene expression within target tissues. Several preclinical studies and clinical trials have tested the efficacy of targeting specific molecules in patients with HNSCC, using genetic therapy approaches. This review discusses promising preclinical and clinical approaches and new directions for HNSCC gene therapy.

STAT3 activation contributes directly to Epstein-Barr virus-mediated invasiveness of nasopharyngeal cancer cells in vitro.

Nasopharyngeal cancer (NPC) is an Epstein-Barr virus (EBV)-associated head and neck cancer prevalent in Asia. Although with reasons not fully understood, the intrinsic invasiveness of NPC is believed to be EBV-linked. Recently, EBV was found to induce STAT3 activation. Constitutive STAT3 activation correlated with advanced clinical staging in NPC. We hypothesized that STAT3 activation by EBV directly contributes to the intrinsic invasiveness of NPC cells. Phospho-STAT3-Tyr705 was detected in high percentage of NPC tumors (7/10 cases). Using a paired NPC cell line model, HONE-1 and the EBV-infected counterpart, HONE-1-EBV, we found that HONE-1-EBV expressed a higher level of phospho-STAT3-Tyr705 and was approximately 11-fold more invasive than HONE-1. In HONE-1-EBV, STAT3 siRNA targeting inhibited both spontaneous and serum-induced invasion, as well as cell growth. Conversely, activation of STAT3 (by expressing an activated STAT3 mutant, namely STAT3C) in the parental HONE-1, mimicking EBV-induced STAT3 activation, significantly enhanced its invasiveness and proliferation, which was accompanied by increased expression of markers of mesenchymal status, proliferation and anti-apoptosis. Our results demonstrated that EBV-induced STAT3 activation is responsible for NPC cell proliferation and invasion. This was further confirmed by a small molecule inhibitor of JAK/STAT3, JSI-124. JSI-124 inhibited STAT3 activation in HONE-1-EBV, with subsequent growth inhibition, induction of PARP cleavage, abrogation of anchorage-independent growth and invasion. We found that EBV-independent activation of STAT3 by a growth factor, EGF, also contributed to NPC invasion. In conclusion, EBV-induced STAT3 activation directly contributes to the intrinsic invasiveness of NPC cells and STAT3 targeting may be beneficial in treating aggressive NPC.

Improving Response Rates to EGFR-Targeted Therapies for Head and Neck Squamous Cell Carcinoma: Candidate Predictive Biomarkers and Combination Treatment with Src Inhibitors.

The epidermal growth factor receptor- (EGFR-) directed antibody, cetuximab, was FDA-approved for the treatment of squamous cell carcinoma of the head and neck (SCCHN) in 2006. Additional EGFR-targeting agents in clinical development for SCCHN include other EGFR-directed antibodies, tyrosine kinase inhibitors and antisense DNA. Although the majority of SCCHN overexpress EGFR, SCCHN clinical responses to EGFR-targeting agents have been modest. Molecular predictors for SCCHN response to EGFR-targeted therapies have not been identified. However, molecular correlate studies in lung cancer and colon cancer, which have EGFR-targeted therapeutics FDA-approved for treatment, may provide insights. We describe candidate predictive markers for SCCHN response to EGFR-targeted therapies and their prevalence in SCCHN. Clinical response will likely be improved by targeted therapy combination treatments. Src family kinases mediate EGFR-dependent and -independent tumor progression pathways in many cancers including SCCHN. Several Src-targeting agents are in clinical development for solid malignancies. Molecular correlate studies for Src-targeting therapies are few and biomarkers correlated with patient response are limited. Identifying SCCHN patients who will respond to combined EGFR- and Src-targeting will require further characterization of molecular correlates. We discuss rationale for EGFR and Src co-targeting for SCCHN treatment and describe recent clinical trials implementing combined Src- and EGFR-targeted therapeutics.

Constitutive activation of signal transducer and activator of transcription 5 contributes to tumor growth, epithelial-mesenchymal transition, and resistance to epidermal growth factor receptor targeting.

PURPOSE: Signal transducer and activator of transcription 5 (STAT5) is activated in squamous cell carcinoma of the head and neck (SCCHN), where targeting of STAT5 inhibits tumor growth in vitro and in vivo. The role of STAT5 activation in carcinogenesis, tumor progression, and response to therapy remains incompletely understood. In this study, we investigated the effects of STAT5 activation on squamous epithelial carcinogenesis and response to therapy. EXPERIMENTAL DESIGN: The functional consequences of STAT5 activation in squamous epithelial carcinogenesis were examined using cells derived from normal (Het-1A) and transformed mucosal epithelial cells engineered to express constitutive-active mutants of STAT5. RESULTS: The growth rate of stable clones derived from both normal and transformed squamous epithelial cells expressing the constitutive-active STAT5 was increased. In SCCHN xenografts, tumor volumes were increased in constitutive-active STAT5 mutant cells compared with vector-transfected controls. Constitutive activation of STAT5 significantly increased cell migration and invasion through Matrigel, as well as the transforming efficiency of SCCHN cells in vitro, as assessed by soft agar assays. The constitutive-active STAT5 clones derived from SCCHN cells showed changes consistent with an epithelial-mesenchymal transition including decreased expression of E-cadherin and increased vimentin in comparison with control transfectants. In these cells, STAT5 activation was associated with resistance to cisplatin-mediated apoptosis and growth inhibition induced by the epidermal growth factor receptor tyrosine kinase inhibitor, erlotinib. CONCLUSIONS: These results suggest that constitutive STAT5 signaling enhances tumor growth, invasion, and epithelial-to-mesenchymal transition in squamous epithelial carcinogenesis and may contribute to resistance to epidermal growth factor receptor tyrosine kinase inhibitor and chemotherapy.

Combined targeting of epidermal growth factor receptor, signal transducer and activator of transcription-3, and Bcl-X(L) enhances antitumor effects in squamous cell carcinoma of the head and neck.

Squamous cell carcinoma of the head and neck (SCCHN) is a leading cause of cancer deaths worldwide. Epidermal growth factor receptor (EGFR), an upstream mediator of signal transducer and activator of transcription (STAT)-3 is overexpressed in a variety of cancers, including SCCHN. Therapies such as monoclonal antibodies and tyrosine kinase inhibitors targeting EGFR have demonstrated limited antitumor efficacy, which may be explained, in part, by persistent STAT3 activation despite EGFR inhibition. STAT3 activation induces expression of target genes in SCCHN, including Bcl-X(L), a mediator of antiapoptotic activity. Bcl-X(L) is commonly overexpressed in SCCHN where it correlates with chemoresistance, making it a potential therapeutic target. Targeting the EGFR-STAT3-Bcl-X(L) pathway at several levels, including the upstream receptor, the intracellular transcription factor, and the downstream target gene, has not been investigated previously. Using erlotinib, an EGFR-specific reversible tyrosine kinase inhibitor in combination with a STAT3 transcription factor decoy, we found enhanced antitumor effects in vitro and in vivo. The combination of the STAT3 decoy and gossypol, a small molecule targeting Bcl-X(L), also yielded enhanced inhibition of cell proliferation. The triple combination of erlotinib, STAT3 decoy, and gossypol further enhanced cell growth inhibition and apoptosis in vitro, and it down-regulated signaling molecules further downstream of the EGFR-STAT3 signaling pathway, such as cyclin D1. These results suggest that combined targeting of several components of an oncogenic signaling pathway may be an effective therapeutic strategy for SCCHN.

Antitumor mechanisms of systemically administered epidermal growth factor receptor antisense oligonucleotides in combination with docetaxel in squamous cell carcinoma of the head and neck.

Squamous cell carcinoma of the head and neck (SCCHN) is one of the most common malignancies worldwide, with low 5-year survival rates. Current strategies that block epidermal growth factor receptor (EGFR) have limited effects when administered as single agents. Targeting EGFR via intratumoral administration of phosphorothioate-modified antisense oligonucleotides has antitumor efficacy in xenograft models of SCCHN. Because intratumoral delivery of therapeutic agents has limited clinical application, the present study was undertaken to examine the therapeutic mechanisms of systemically delivered phosphorothioate-modified EGFR antisense oligonucleotides alone, or in combination with docetaxel, in a SCCHN xenograft model. EGFR antisense oligonucleotides were administered at 5 mg/kg i.p. daily in athymic mice bearing 1483 human SCCHN xenografts alone or in combination with docetaxel at 2.5 mg/kg i.p. once a week for 4 weeks. Administration of EGFR antisense oligonucleotides in combination with docetaxel improved antitumor efficacy and resulted in lower expression levels of EGFR, fewer proliferating cells, and more apoptotic cells in the tumors compared with controls. Systemic administration of phosphorothioated EGFR antisense oligonucleotides for 30 days increased the retention of docetaxel in the tumor by approximately 4-fold compared with tumors treated with docetaxel alone or docetaxel and EGFR sense oligonucleotides (P < 0.05). Combination of EGFR antisense oligonucleotides with low doses of docetaxel has antitumor efficacy, and it may be an effective treatment strategy for SCCHN.

Clinical applications of gene therapy in head and neck cancer.

Despite advances in surgery, radiotherapy, and the incorporation of novel systemic agents into treatment, long-term outcomes of patients with head and neck cancer remain unsatisfactory. The growing understanding of head and neck cancer biology suggests that targeting molecular events governing carcinogenesis or tumor progression may provide novel therapeutic approaches for head and neck cancer. Squamous cell carcinoma of the head and neck (SCCHN) is characterized by locoregional spread and is clinically accessible, making it an attractive target for intratumoral gene therapy, a potentially efficacious experimental treatment. Systemic delivery of gene therapy may be also possible, albeit with several limitations. In this review we will discuss the rationale, delivery methods, and accumulated clinical data with cancer gene therapy in SCCHN.

Antitumor mechanisms of combined gastrin-releasing peptide receptor and epidermal growth factor receptor targeting in head and neck cancer.

Head and neck squamous cell carcinoma (HNSCC) is characterized by epidermal growth factor receptor (EGFR) overexpression, where EGFR levels correlate with survival. To date, EGFR targeting has shown limited antitumor effects in head and neck cancer when administrated as monotherapy. We previously identified a gastrin-releasing peptide/gastrin-releasing peptide receptor (GRP/GRPR) aurocrine regulatory pathway in HNSCC, where GRP stimulates Src-dependent cleavage of EGFR proligands with subsequent EGFR phosphorylation and mitogen-activated protein kinase (MAPK) activation. To determine whether GRPR targeting can enhance the antitumor efficacy of EGFR inhibition, we investigated the effects of a GRPR antagonist (PD176252) in conjunction with an EGFR tyrosine kinase inhibitor (erlotinib). Combined blockade of GRPR and EGFR pathways significantly inhibited HNSCC, but not immortalized mucosal epithelial cell, proliferation, invasion, and colony formation. In addition, the percentage of apoptotic cells increased upon combined inhibition. The enhanced antitumor efficacy was accompanied by increased expression of cleaved poly(ADP-ribose) polymerase (PARP) and decreased phospho-EGFR, phospho-MAPK, and proliferating cell nuclear antigen (PCNA). Using reverse-phase protein microarray (RPPA), we further detected decreased expression of phospho-c-Jun, phospho-p70S6K, and phospho-p38 with combined targeting. Cumulatively, these results suggest that GRPR targeting can enhance the antitumor effects of EGFR inhibitors in head and neck cancer.

Antiproliferative mechanisms of a transcription factor decoy targeting signal transducer and activator of transcription (STAT) 3: the role of STAT1.

We previously developed a transcription factor decoy targeting signal transducer and activator of transcription 3 (STAT3) and reported antitumor activity in both in vitro and in vivo models of squamous cell carcinoma of the head and neck (SCCHN). Based on the known existence of STAT1-STAT3 heterodimers, the high sequence homology between STAT1 and STAT3, as well as expression of both STAT1 and STAT3 in SCCHN, we examined whether the STAT3 decoy interferes with STAT1 signaling. SCCHN cell lines with different STAT1 expression levels (but similar STAT3 levels) were used. Both cell lines were sensitive to the growth-inhibitory effects of the STAT3 decoy compared with a mutant control decoy. Intact STAT1 signaling was demonstrated by interferon-gamma (IFN-gamma)-mediated induction of STAT1 phosphorylation (Tyr701) and interferon-regulatory factor-1 (IRF-1) expression. Treatment with the STAT3 decoy (but not a mutant control decoy) resulted in inhibition of IRF-1 protein expression in both cell lines, indicating specific inhibition of STAT1 signaling by the STAT3 decoy. Because STAT1 is a potential tumor suppressor, we also investigated whether STAT1 signaling mitigated the therapeutic efficacy of the STAT3 decoy. In both PCI-15B and UM-22B cells, STAT1 siRNA treatment resulted in decreased STAT1 expression, without altering the antitumor activity of the STAT3 decoy. Likewise, the antitumor effects of the STAT3 decoy were not altered by STAT1 activation upon IFN-gamma treatment. These results suggest that the therapeutic mechanisms of STAT3 blockade using a transcription factor decoy are independent of STAT1 activation.

Cross-talk between G protein-coupled receptor and epidermal growth factor receptor signaling pathways contributes to growth and invasion of head and neck squamous cell carcinoma.

G protein-coupled receptors (GPCR) and the epidermal growth factor receptor (EGFR) are often both overexpressed and contribute to the growth of cancers by activating autocrine pathways. GPCR ligands have been reported to trigger EGFR signaling via receptor cross-talk in cancer cells. Here, we show that GPCR ligands prostaglandin E2 (PGE2) and bradykinin (BK) activate EGFR signaling. Inhibition of EGFR using several strategies, including small-molecule inhibitors and an EGFR-specific antibody, resulted in partial attenuation of signaling downstream of EGFR. PGE2 and BK triggered EGFR signaling by increasing selective autocrine release of transforming growth factor-alpha (TGF-alpha). Inhibition of tumor necrosis factor-alpha-converting enzyme abrogated BK- or PGE2-mediated activation of EGFR signaling. Both PGE2 and BK stimulated head and neck squamous cell carcinoma (HNSCC) invasion via EGFR. Treatment of HNSCC cells with the BK antagonist CU201 resulted in growth inhibition. The combination of CU201 with the EGFR small-molecule inhibitor erlotinib resulted in additive inhibitory effects on HNSCC cell growth in vitro. Inhibition of the PGE2 synthesis pathway with sulindac induced HNSCC cytotoxicity at high doses (EC(50), 620 micromol/L). However, combined inhibition of both EGFR with the tyrosine kinase inhibitor erlotinib and GPCR with sulindac at low doses of 6 and 310 micromol/L, respectively, resulted in synergistic killing of HNSCC tumor cells. Combined blockade of both EGFR and GPCRs may be a rational strategy to treat cancers, including HNSCC that shows cross-talk between GPCR and EGFR signaling pathways.

Phosphorylation of TNF-alpha converting enzyme by gastrin-releasing peptide induces amphiregulin release and EGF receptor activation.

G protein-coupled receptors induce EGF receptor (EGFR) signaling, leading to the proliferation and invasion of cancer cells. Elucidation of the mechanism of EGFR activation by G protein-coupled receptors may identify new signaling paradigms. A gastrin-releasing peptide (GRP)/GRP receptor-mediated autocrine pathway was previously described in squamous cell carcinoma of head and neck. In the present study, we demonstrate that TNF-alpha converting enzyme (TACE), a disintegrin and metalloproteinse-17, undergoes a Src-dependent phosphorylation that regulates release of the EGFR ligand amphiregulin upon GRP treatment. Further investigation reveals the phosphatidylinositol 3-kinase (PI3-K) as the intermediate of c-Src and TACE, contributing to their association and TACE phosphorylation. Phosphoinositide-dependent kinase 1 (PDK1), a downstream target of PI3-K, has been identified as the previously undescribed kinase to directly phosphorylate TACE upon GRP treatment. These findings suggest a signaling cascade of GRP-Src-PI3-K-PDK1-TACE-amphiregulin-EGFR with multiple points of interaction, translocation, and phosphorylation. Furthermore, knockdown of PDK1 augmented the antitumor effects of the EGFR inhibitor erlotinib, indicating PDK1 as a therapeutic target to improve the clinical response to EGFR inhibitors.

STAT3 as a therapeutic target in head and neck cancer.

The signal transducer and activator of transcription (STAT) proteins relay signals from cytokine receptors and receptor tyrosine kinases on the cell surface to the nucleus, where they affect the transcription of genes involved in normal cell functions, including growth, apoptosis and differentiation. STAT3 has been found to be constitutively active in head and neck squamous cell carcinoma (HNSCC) as well as in other epithelial malignancies. In HNSCC, STAT3 alters the cell cycle, prevents apoptosis, and mediates the proliferation and survival of tumour cells. Several therapeutic approaches are being developed to target STAT3, including molecules that block either dimerisation or DNA binding by STAT3, strategies to decrease STAT3 expression and drugs that inhibit STAT3 function. Strategies that block STAT3 may prove efficacious for cancer treatment.

Decreased STAT1 expression by promoter methylation in squamous cell carcinogenesis.

BACKGROUND: Dysregulation of signal transducers and activators of transcription (STATs) is associated with many cancers, but no role of STAT1 in human tumor progression has been demonstrated. METHODS: We compared STAT1 protein expression in squamous cell carcinoma of the head and neck (SCCHN) tumors (n = 28) and normal oropharyngeal mucosa samples (n = 10) from patients without cancer as assessed by immunoblotting. Stable clones were established from SCCHN 1483 cells that were transfected with a STAT1 expression construct; cell growth and cisplatin-induced apoptosis of the clones and vector control-transfected 1483 cells were compared using trypan blue exclusion and Annexin V staining and expression of the cyclin-dependent kinase inhibitor p21 was assayed by immunoblotting. The growth of STAT1-overexpressing SCCHN 1483 xenograft tumors was compared with that of xenograft tumors derived from cells transfected with vector control DNA. DNA from SCCHN tumors (n = 16) and paired peripheral blood lymphocytes were analyzed for STAT1 mutations and promoter methylation using methylation-specific polymerase chain reaction and bisulfite sequencing. SCCHN cell lines (PCI-15b, 1483, and UM-22B) were treated with the demethylating agent azacytidine alone or in combination with the cytotoxic drug cisplatin, and expression of STAT1 and p21 were monitored by immunoblotting. All statistical tests were two-sided. RESULTS: STAT1 levels were statistically significantly lower in the SCCHN tumors than normal mucosa (median = 0.8 relative units versus 2.4, difference = 1.6, 95% confidence interval [CI] = 1.3 to 2.0, P < .001). Overexpression of STAT1 abrogated the growth of SCCHN cells and xenograft tumors and increased p21 expression. STAT1 expression levels of the tumors with STAT1 promoter methylation (n = 12) were lower than those of tumors (n = 4) without promoter methylation of STAT1 (P = .008). Azacytidine treatment increased expression of STAT1 and p21 in SCCHN cell lines and increased apoptosis in cisplatin-treated 1483 cells compared with cisplatin treatment alone (mean = 61.3% versus 25.8%, difference = 35.5%, 95% CI = 24.5% to 43.4%; P = .028). CONCLUSION: STAT1 can function as a tumor suppressor in SCCHN cells. Silencing of the STAT1 gene via promoter methylation may contribute to SCCHN tumor cell growth.

Advances in molecular diagnostics and therapeutics in head and neck cancer.

Extensive treatment-related morbidities and stagnant survival rates over the past few decades for patients with squamous cell cancer of the head and neck (SCCHN) emphasize the need for novel diagnostics and therapeutics based on the molecular characteristics of the tumor. The development of an early detection test remains largely preliminary. Much attention has recently been given to saliva-based early detection assays that use accepted tumor markers such as p53 and DNA methylation. Most of these studies have focused on feasibility as opposed to prospective clinical trials. To date, early detection saliva assays have failed to yield a high enough sensitivity and specificity for broad population-based screening. The use of saliva as a noninvasive, inexpensive, and accessible diagnostic substrate remains desirable. Unlike SCCHN diagnostics, molecular-targeted therapies for SCCHN will soon be a reality, with many more compounds in the pipeline. The most promising of these drugs target the epidermal growth factor receptor (EGFR), which is known to be overexpressed in squamous cell carcinomas. Cetuximab, a monoclonal EGFR antibody, has shown efficacy in combination with radiotherapy in advanced SCCHN in a recent phase III trial and is currently being petitioned for US Food and Drug Administration approval. Likewise, erlotinib, an EGFR tyrosine kinase inhibitor, has shown favorable results in phase II trials as monotherapy and in combination with chemotherapy. Gefitinib, another EGFR tyrosine kinase inhibitor, has shown efficacy as monotherapy, in combination with chemotherapy, and with chemoradiotherapy. At least two phase III trials of gefitinib in patients with advanced SCCHN are ongoing. Such low-toxicity, tumor-specific targeting strategies will soon be available for patients with head and neck cancer. The challenge is to establish assays to determine which patients are most likely to benefit from these agents.