Molecular therapy in head and neck oncology

Altered metabolism in head and neck squamous cell carcinoma: an opportunity for identification of novel biomarkers and drug targets

Tumor cells were first shown to exhibit a distinct metabolic phenotype over 80 years ago. Since then, it has become clear that multiple oncogenic events contribute to the development of a metabolic phenotype that supports rapid proliferation. Because this phenotype represents an essential component of tumorigenesis and disease progression, it also represents a potential source of biomarkers associated with aggressive disease. In addition, the addiction of tumor cells to specific nutrients and the up-regulation of key metabolic enzymes provide unique opportunities for pharmacologic manipulation. Despite the use of multimodality treatment, survival rates for patients with advanced head and neck squamous cell carcinoma (HNSCC) remain low, partially attributed to the development of drug resistance. In this review, we evaluate the role of altered HNSCC metabolism as both a source of novel biomarkers and a means to bypass resistance mechanisms to conventional forms of therapy.

A critical role of c-Cbl-interacting protein of 85 kDa in the development and progression of head and neck squamous cell carcinomas through the ras-ERK pathway

Activation of the transforming growth factor (TGF) α/epidermal growth factor receptor (EGFR)-mediated signaling pathway is a common mechanism for dysregulated growth of head and neck squamous cell carcinoma (HNSCC). c-Cbl-interacting protein of 85 kDa (CIN85) is an adaptor protein that facilitates EGFR internalization. Little is known, however, about a role of CIN85 in EGFR signaling as well as its relevance to tumor development and progression of HNSCC. Here, we demonstrate that CIN85 is highly expressed in HNSCC tumor samples compared with adjacent normal tissues, and this overexpression is significantly correlated with advanced clinical stage. The experiments using CIN85-overexpressing and knockdown HNSCC cell lines showed that CIN85 promotes HNSCC growth and facilitates EGFR internalization without apparently affecting phosphorylation of EGFR. Moreover, CIN85 promoted TGF-α-induced activation of Ras and phosphorylation of downstream molecules such as c-Raf, MEK, and extracellular signal-regulated kinase, leading to expression of c-Myc that is critical for sustained proliferation of HNSCC. Taken together, these findings suggest that CIN85 not only controls EGFR internalization but also promotes the EGFR-mediated tumor development and progression, and thus, CIN85 may serve as a potential therapeutic target in a subset of HNSCC.

Chemopreventive potential of natural compounds in head and neck cancer

Head and neck squamous cell carcinoma (HNSCC) is one of the most fatal cancers worldwide. Despite advances in the management of HNSCC, the overall survival for patients has not improved significantly due to advanced stages at diagnosis, high recurrence rate after surgical removal, and second primary tumor development, which underscore the importance of novel strategies for cancer prevention. Cancer chemoprevention, the use of natural or synthetic compounds to prevent, arrest, or reverse the process of carcinogenesis at its earliest stages, aims to reverse premalignancies and prevent second primary tumors. Genomics and proteomics information including initial mutation, cancer promotion, progression, and susceptibility has brought molecularly targeted therapies for drug development. The development of preventive approaches using specific natural or synthetic compounds, or both, requires a depth of understanding of the cross-talk between cancer signaling pathways and networks to retain or enhance chemopreventive activity while reducing known toxic effects. Many natural dietary compounds have been identified with multiple molecular targets, effective in the prevention and treatment of cancer. This review describes recent advances in the understanding of the complex signaling networks driving cancer progression and of molecularly targeted natural compounds under preclinical and clinical investigation.

Transient alteration of cellular redox buffering before irradiation triggers apoptosis in head and neck carcinoma stem and non-stem cells

Background

Head and neck squamous cell carcinoma (HNSCC) is an aggressive and recurrent malignancy owing to intrinsic radioresistance and lack of induction of apoptosis. The major focus of this work was to design a transient glutathione depleting strategy during the course of irradiation of HNSCC in order to overcome their radioresistance associated with redox adaptation.

Methodology/Principal Findings

Treatment of SQ20B cells with dimethylfumarate (DMF), a GSH-depleting agent, and L-Buthionine sulfoximine (BSO), an inhibitor of GSH biosynthesis 4 h before a 10 Gy irradiation led to the lowering of the endogenous GSH content to less than 10% of that in control cells and to the triggering of radiation-induced apoptotic cell death. The sequence of biochemical events after GSH depletion and irradiation included ASK-1 followed by JNK activation which resulted in the triggering of the intrinsic apoptotic pathway through Bax translocation to mitochondria.

Conclusions

This transient GSH depletion also triggered radiation-induced cell death in SQ20B stem cells, a key event to overcome locoregional recurrence of HNSCC. Finally, our in vivo data highlight the relevance for further clinical trials of endogenous redox modulation to enhance the cytotoxic effects of radiotherapy.

Chemoprevention of Head and Neck Cancer by Green Tea Extract: EGCG-The Role of EGFR Signaling and "Lipid Raft"

Over the past decade dose-intensified chemo-radiotherapy or molecular targeted therapy has been introduced into the treatments of head and neck squamous cell carcinoma (HNSCC) to improve the outcomes of this dismal disease. However, these strategies have revealed only limited efficacy so far. Moreover, the frequent occurrences of second primary tumor further worsen the prognosis of patients. In this context, early detection and chemoprevention appear to be a realistic and effective method to improve the prognosis as well as quality of life in patients with HNSCC. In this short paper, we discuss the potential of green tea extract, (-)-epigallocatechin-3-galate (EGCG) in HNSCC chemoprevention, focusing on two aspects that are provided recently: (1) evidence of clinical efficacy and (2) unique biological effects on "lipid raft" that emerged as an important platform of numerous biophysical functions, for example, receptor tyrosin kinases (RTKs) signalings including epidermal growth factor receptor (EGFR), which play critical roles in HNSCC carcinogenesis.

14-3-3 zeta is a molecular target in guggulsterone induced apoptosis in head and neck cancer cells

Background

The five-year survival rates for head and neck squamous cell carcinoma (HNSCC) patients are less than 50%, and the prognosis has not improved, despite advancements in standard multi-modality therapies. Hence major emphasis is being laid on identification of novel molecular targets and development of multi-targeted therapies. 14-3-3 zeta, a multifunctional phospho-serine/phospho-threonine binding protein, is emerging as an effector of pro-survival signaling by binding to several proteins involved in apoptosis (Bad, FKHRL1 and ASK1) and may serve as an appropriate target for head and neck cancer therapy. Herein, we determined effect of guggulsterone (GS), a farnesoid X receptor antagonist, on 14-3-3 zeta associated molecular pathways for abrogation of apoptosis in head and neck cancer cells.

Methods

Head and neck cancer cells were treated with guggulsterone (GS). Effect of GS-treatment was evaluated using cell viability (MTT) assay and apoptosis was verified by annexin V, DNA fragmentation and M30 CytoDeath antibody assay. Mechanism of GS-induced apoptosis was determined by western blotting and co-IP assays using specific antibodies.

Results

Using in vitro models of head and neck cancer, we showed 14-3-3 zeta as a key player regulating apoptosis in GS treated SCC4 cells. Treatment with GS releases BAD from the inhibitory action of 14-3-3 zeta in proliferating HNSCC cells by activating protein phosphatase 2A (PP2A). These events initiate the intrinsic mitochondrial pathway of apoptosis, as revealed by increased levels of cytochrome c in cytoplasmic extracts of GS-treated SCC4 cells. In addition, GS treatment significantly reduced the expression of anti-apoptotic proteins, Bcl-2, xIAP, Mcl1, survivin, cyclin D1 and c-myc, thus committing cells to apoptosis. These events were followed by activation of caspase 9, caspase 8 and caspase 3 leading to cleavage of its downstream target, poly-ADP-ribose phosphate (PARP).

Conclusion

GS targets 14-3-3 zeta associated cellular pathways for reducing proliferation and inducing apoptosis in head and neck cancer cells, warranting its investigation for use in treatment of head and neck cancer.

Zinc deficiency activates S100A8 inflammation in the absence of COX-2 and promotes murine oral-esophageal tumor progression

Zinc (Zn)-deficiency (ZD) is implicated in the pathogenesis of human oral-esophageal cancers. Previously, we showed that in ZD mice genetic deletion of cyclooxygenase-2 (Cox-2) enhances N-nitrosomethylbenzylamine-induced forestomach carcinogenesis. By contrast, Cox-2 deletion offers protection in Zn-sufficient (ZS) mice. We hypothesize that ZD activates pathways insensitive to COX-2 inhibition, thereby promoting carcinogenesis. This hypothesis is tested in a Cox-2^−/− mouse tongue cancer model that mimics pharmacologic blockade of COX-2 by firstly examining transcriptome profiles of forestomach mucosa from Cox-2^−/− and wild-type mice on a ZD vs. ZS diet, and secondly investigating the roles of identified markers in mouse forestomach/tongue preneoplasia and carcinomas. In Cox-2^−/− mice exposed to the tongue carcinogen 4-nitroquinoline 1-oxide, dietary ZD elicited tongue/esophagus/forestomach carcinomas that were prevented by ZS. The precancerous ZD:Cox-2^−/−vs. ZS:Cox-2^−/− forestomach had an inflammatory signature with upregulation of the proinflammation genes S100a8 and S100a9. Bioinformatics analysis revealed overrepresentation of inflammation processes comprising S100a8/a9 and an nuclear factor (NF)-κB network with connectivity to S100A8. Immunohistochemistry revealed co-overexpression of S100A8, its heterodimeric partner S100A9, the receptor for advanced glycation end-products (RAGE), NF-κB p65, and cyclin D1, in ZD:Cox-2^−/− forestomach/tongue preneoplasia and carcinomas, evidence for the activation of a RAGE-S100A8/A9 inflammatory pathway. Accumulation of p53 in these carcinomas indicated activation of additional inflammatory pathways. Zn-replenishment in ZD:Cox-2^−/−mice reversed the inflammation and inhibited carcinogenesis. Thus, ZD activates alternative inflammation-associated cancer pathways that fuel tumor progression and bypass the antitumor effect of Cox-2 ablation. These findings have important clinical implications, as combination cancer therapy that includes Zn may improve efficacy.

Cognitive functioning after radiotherapy or chemoradiotherapy for head-and-neck cancer

PURPOSE

To perform a comprehensive cognitive function (CF) assessment in patients who were relapse free after curative intent radiotherapy (RT) or chemoradiotherapy for squamous cell carcinoma of the head and neck.

METHODS AND MATERIALS

Patients underwent neuropsychological tests to assess their objective CF; completed questionnaires to assess subjective CF, quality of life, and affect; and underwent blood tests to assess hematologic, biochemical, endocrine, and cytokine status. Retrospectively, the dosimetry of incidental radiation to the brain was determined for all patients, and the dose intensity of cisplatin was determined in those who had undergone chemoradiotherapy.

RESULTS

A total of 10 patients were enrolled (5 treated with radiotherapy only and 5 with radiotherapy and cisplatin). The mean time from the end of treatment was 20 months (range, 9-41). All patients were able to complete the assessment protocol. Of the 10 patients, 9 had impaired objective CF, with memory the most severely affected. The severity of memory impairment correlated significantly with the radiation dose to the temporal lobes, and impaired dexterity correlated significantly with the radiation dose to the cerebellum, suggesting that these deficits might be treatment related. Patients receiving cisplatin appeared to have poorer objective CF than patients receiving only RT, although this difference did not achieve statistical significance, likely owing to the small sample size. Consistent with the published data, objective CF did not correlate with subjective CF or quality of life. No association was found between objective CF and patients' affect, hematologic, biochemical, endocrine, and cytokine status.

CONCLUSION

Neuropsychological testing is feasible in squamous cell carcinoma of the head-and-neck survivors. The findings were suggestive of treatment-related cognitive dysfunction. These results warrant additional investigation.

Imaging: Mass spectrometry in HNSCC--a peek at response prediction?

EGFR inhibitors provide benefit in patients with advanced and metastatic head and neck squamous cell carcinoma (HNSCC). Mass spectrometry profiling has been used to predict outcome in patients with HNSCC after EGFR inhibitor treatment, and may enable prior identification of patients most likely to benefit from these therapies. however, further validation in prospective studies is needed.

Molecular radiobiology meets clinical radiation oncology

BACKGROUND

The 2nd Langendorff Congress in Freiburg in Breisgau (Germany) gathered basic and translational scientists as well as clinicians interested in recent developments in molecular and clinical radiobiology. The topics ranged from the most recent insight into the organisation of the DNA damage response and radiotherapeutically relevant cell death mechanisms to biological imaging for treatment planning and advances in the understanding of the molecular biological effects of particle beams. Clinical aspects of stem cell and tumour stem cell biology as well as of angiogenesis and hypoxia, the search for novel molecular radiosensitisers and potential strategies for exploitation of the immune system to further improve tumour radiotherapy were also discussed.

RESULTS AND CONCLUSION

This report surveys the presentations at the meeting, considering their significance in light of the literature, and documents the increasing importance of molecular radiobiology for clinical radiooncology.

The molecular pathogenesis of head and neck cancer

Head and neck cancer arises from a series of molecular alterations progressive from dysplasia to carcinoma in situ, and finally invasive carcinoma. Risk factors associated with head and neck cancer include tobacco, alcohol and viral infection. There are genetic alterations in pre-cancerous cells that contribute to transformation. The accumulation of these alterations facilitates tumor development. Additionally, the tumor microenvironment enables tumor progression. The cooperative effect of molecular alterations in the tumor cells and compensatory microenvironment changes enable tumors to invade and metastasize. This review focuses on the genes and molecules altered during the progression of head and neck cancer with an emphasis on the genetic, molecular and phenotypic changes during the pathogenesis of head and neck cancer. Therapeutic strategies that target key changes in the tumor cells and/or stromal cells in the tumor microenvironment are discussed.

Charged particles in radiation oncology

Radiotherapy is one of the most common and effective therapies for cancer. Generally, patients are treated with X-rays produced by electron accelerators. Many years ago, researchers proposed that high-energy charged particles could be used for this purpose, owing to their physical and radiobiological advantages compared with X-rays. Particle therapy is an emerging technique in radiotherapy. Protons and carbon ions have been used for treating many different solid cancers, and several new centers with large accelerators are under construction. Debate continues on the cost:benefit ratio of this technique, that is, on whether the high costs of accelerators and beam delivery in particle therapy are justified by a clear clinical advantage. This Review considers the present clinical results in the field, and identifies and discusses the research questions that have resulted with this technique.