Gefitinib ('Iressa'), an epidermal growth factor receptor tyrosine kinase inhibitor, mediates the inhibition of lymph node metastasis in oral cancer cells

Role of Molecular Targeted Therapeutic Drugs in Treatment of Oral Squamous Cell Carcinoma: Development and Current Strategies—A Review Article

Because of active advancement in the field of biomedicine, people have in-depth knowledge of biological nature of malignant tumors and are able to recognized the overexpression of different molecules such as vascular endothelial growth factor receptor, cyclin-dependent kinase, and programmed cell death receptor. Presently, various targeted therapeutic drugs are used in different clinical trials in those patients suffering from oral squamous cell carcinoma. In this review, we converse about the various targeted therapeutic drugs and their advancement in the treatment of oral squamous cell carcinoma. This review scrutinizes the existing documentation in the literature related to the targeted therapies for oral squamous cell carcinoma. English language articles were searched in various databases such as PubMed, Scopus, Science Direct, and Google Scholar. The keywords used for searching are “oral squamous cell carcinoma,” “targeted therapy,” and “therapeutic drugs.”

RAN and YBX1 are required for cell proliferation and IL-4 expression and linked to poor prognosis in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is one of the most common malignancies in the world, with a high mortality rate. RAN is a member of the Ras GTPase family and is overexpressed in a range of cancers, however, the relationship between RAN and OSCC is rarely reported. In this study, we found that RAN is overexpressed in OSCC tissues. RAN inhibition retarded OSCC cell proliferation and led to apoptosis and cell cycle arrest. Knockdown of RAN inhibited tumor growth in vivo. Strikingly, we found that RAN and oncogene Y-box binding protein-1 (YBX1) are positively associated with the immune infiltrates of CD4⁺ Th2 cells in multiple types of cancer, and can promote IL-4 expression. IL-4 treatment can partially rescue RAN knockdown-induced cell apoptosis in OSCC cells. Moreover, overexpression of RAN could rescue cell growth inhibition caused by knockdown of YBX1. Furthermore, patients with low expression of both RAN and YBX1 had better overall survival than others. Collectively, these findings indicate that RAN is a target of YBX1. RAN and YBX1 are required for cell proliferation and IL-4 expression. RAN and YBX1 are co-expressed and can serve as potential co-biomarkers for poor prognosis in OSCC.

Inhibitory effect of cathepsin K inhibitor (ODN-MK-0822) on invasion, migration and adhesion of human breast cancer cells in vitro

Approximately 90% of patients with advanced breast cancer develop bone metastases; an event that results in severe decrease of quality of life and a drastic deterioration in prognosis. Therefore, to increase the survival of breast cancer patients, the development of new therapeutic strategies to impair metastatic process and skeletal complications is critical. Previous studies on the role of cathepsin K (CTSK) in metastatic spreading led to several strategies for inhibition of this molecule such as MIV-711 (Medivir), balicatib and odanacatib (ODN) which were on trial in the past. The present study intended to assess the anti-metastatic efficacy of ODN in breast cancer cells. Human breast cancer cell lines MDA-MB-231 were treated with different concentrations of ODN and performed invasion, adhesion and migration assays and, RT-PCR and western blot to evaluate the effect of ODN on the metastatic potential of breast cancer cells. ODN markedly decreased wound healing cell migration, invasion and adhesion at a dose dependent manner. ODN inhibits cell invasion by decreasing the matrix metalloproteinase (MMP-9) with the upregulation of TIMP-1 expression. ODN effectively inhibited the phosphorylation of extracellular signal-regulated kinase (ERK), p38, and c-Jun N-terminal Kinase (JNK), and blocked the expression of β-integrins and FAK proteins. ODN also significantly inhibited PI3K downstream targets Rac1, Cdc42, paxillin and Src which are critical for cell adhesion, migration and cytoskeletal reorganization. ODN exerts anti-metastatic action through inhibition of signaling pathway for MMP-9, PI3K and MAPK. This indicates potential therapeutic effects of ODN in the treatment of metastatic breast cancer.

EGFR enhances the stemness and progression of oral cancer through inhibiting autophagic degradation of SOX2

Epidermal growth factor receptor (EGFR) is highly expressed in head and neck squamous cell carcinoma (HNSCC) and correlates with poor prognosis. EGFR has been demonstrated to be associated with cancer stem cell traits in HNSCC. However, the underlying molecular mechanism is far from elucidated. Here, SOX2, one of the most important stem cell markers, was identified as a binding partner and substrate of EGFR. EGFR signaling inhibition decreases SOX2 expression by promoting its autophagic degradation. Mechanistically, EGFR activation induces SOX2 phosphorylation at the Y277 site and reduces its ubiquitination, which inhibits its association with p62 and subsequent autophagic degradation. Gefitinib, an EGFR tyrosine kinase inhibitor, shows in vitro and in vivo protective effects against oral cancer cells that can be reversed through autophagy inhibition. Our study suggests that EGFR plays an important role in the development of cancer stem cells by stabilizing SOX2. Targeting EGFR in combination with conventional chemotherapy might be a promising strategy for the treatment of HNSCC through elimination of cancer stem cells.

Progress in targeted therapeutic drugs for oral squamous cell carcinoma

With the rapid development of biomedicine, people have a deeper understanding with the biological characteristics of malignant tumors, and begin to notice that in most tumors, there are over-expression of several molecules such as epidermal growth factor receptor(EGFR), vascular endothelial growth factor (VEGF) and its receptors,mammalian target of rapamycin(mTOR),programmed cell death receptor-1(PD-1),cyclin-dependent kinases(CDKs) and so on, whose levels are closely related to the prognosis of tumors. It has been found that the drugs targeting the above molecules can significantly improve the survival rate of cancer patients, and have the advantages of high selectivity, low toxicity and high therapeutic index. Targeted drugs, as new ones in the field of cancer, have achieved good efficacy in most tumor treatments. Oral cancer is an aggressive malignant tumour that is prone to relapse and metastasis. More than 90% of them are squamous cell carcinoma, and the 5-year survival rate remains at about 50%-60%.The proposing of targeted therapy opens up a new way for the treatment of oral cancer and brings dawn to patients with advanced diseases. Currently,a variety of targeted therapeutic drugs are being tested in various clinical trials in patients with oral squamous cell carcinoma(OSCC)·In this paper, we discuss the research progress of targeted therapeutic drugs in the treatment of OSCC in recent years.

Inhibition of epidermal growth factor receptor improves antitumor efficacy of vemurafenib in BRAF-mutant human melanoma in preclinical model

Oncogenic activation of the epidermal growth factor receptor (EGFR) signaling pathway occurs in a variety of tumor types, albeit in human melanoma, the contribution of EGFR is still unclear. The potential role of EGFR was analyzed in four BRAF-mutant, one NRAS-mutant and one wild-type NRAS-BRAF-carrying human melanoma cell lines. We have tested clinically available reversible tyrosine kinase inhibitors (TKIs) gefitinib and erlotinib, irreversible EGFR-TKI pelitinib and a reversible experimental compound PD153035 on in-vitro proliferation, apoptosis, migration as well as in-vivo metastatic colonization in a spleen-liver model. The presence of the intracellular domain of EGFR protein and its constitutive activity were demonstrated in all cell lines. Efficacies of EGFR-TKIs showed significant differences, and irreversible inhibition had the strongest antitumor potential. Compared with BRAF-mutant cells, wild-type BRAF was associated with relative resistance against gefitinib. In combination with gefitinib, selective mutant BRAF-inhibitor vemurafenib showed additive effect in all BRAF-mutant cell lines. Treatment of BRAF-mutant cells with gefitinib or pelitinib attenuated in-vitro cell migration and in-vivo colonization. Our preclinical data suggest that EGFR is a potential target in the therapy of BRAF-mutant malignant melanoma; however, more benefits could be expected from irreversible EGFR-TKIs and combined treatment settings.

Enhancing chemosensitivity in oral squamous cell carcinoma by lentivirus vector-mediated RNA interference targeting EGFR and MRP2

Oral cancer is the eighth most common type of cancer among men worldwide, with an age-standardized rate of 6.3 per 100,000, and is the fourth leading cause of cancer-associated mortality among men in Taiwan. Cisplatin and 5-fluorouracil (5-FU) are two of the most frequently utilized chemotherapy drugs for the treatment of oral cancer. Although oral cancer patients initially benefit from chemotherapy with these drugs, they may develop resistance to them, which worsens their prognosis and reduces survival rates. It has been reported that increased levels of epidermal growth factor receptor (EGFR) and multidrug resistance-associated protein 2 (MRP2) induce drug resistance in numerous types of human cancer. Therefore, the present study employed lentivirus vector-mediated RNA interference (RNAi) in order to target the genes encoding EGFR and MRP2 in the oral squamous cell carcinoma cell line OC2. It was observed that RNAi-mediated downregulation of EGFR or MRP2 increased the sensitivity to 5-FU and cisplatin in OC2 cells. Downregulation of EGFR resulted in significant suppression of OC2 tumor growth following 5-FU administration. However, simultaneous downregulation of the two genes did not further suppress the tumor growth, indicating that MRP2 does not have a significant role in the chemosensitivity of EGFR-downregulated cells to 5-FU. In contrast, downregulation of MRP2 was demonstrated to significantly enhance the therapeutic effects of cisplatin in EGFR-downregulated OC2 tumors. The observation that the expression of MRP2 was positively correlated with the level of cisplatin resistance in cells suggests that RNAi-mediated downregulation of MRP2 may be applicable as a therapeutic approach toward reversing MRP2-dependent cisplatin resistance in oral cancer.

CD147 and Ki-67 overexpression confers poor prognosis in squamous cell carcinoma of oral tongue: a tissue microarray study

OBJECTIVE

Squamous cell carcinoma of the oral tongue (SCCOT) exhibits high risk for recurrence and regional metastasis even after surgical resection. We assessed the clinicopathologic and prognostic significance of a group of functionally related biomarkers.

STUDY DESIGN

We used a tissue microarray consisting of SCCOT from 32 patients for this study. These patients were treated at the University of Texas MD Anderson Cancer Center from 1995 to 2008. Biomarker expression levels were examined by immunohistochemistry and graded semiquantitatively to determine their prognostic significance.

RESULTS

CD147 and Tp63 expressions were significantly associated with a higher T stage and Ki-67 labeling index, as well as a shorter overall survival (OS) rate. Expression of Tp63 associated positively with poorly differentiated histology. There was significant association of Tp63 with the expression levels of CD147 and Glut-1. Glut-1 overexpression was marginally associated with a higher T stage. There was no prognostic significance of CD44 v6 expression in SCCOT.

CONCLUSION

SCCOT with CD147 overexpression in combination with high Ki-67 labeling index had poor OS. CD147 and Ki-67 overexpression is associated with aggressive disease with poor prognosis in SCCOT.

Molecular and cellular processes underlying the hallmarks of head and neck cancer

The hallmarks of cancer were updated by Hanahan and Weinberg in 2011. Here we discuss the updated hallmarks in relation to what is known of the molecular and cellular processes underlying the development of head and neck squamous cell carcinoma (HNSCC). Several mechanisms are described, and recent surveys of HNSCC suggest a limited number of mutations, from which more mechanisms may emerge. There are also epigenetic changes to the control of normal processes. More than one mechanism underlies each hallmark. Processes essential to the development of HNSCC need not be essential to the proliferation of the fully developed tumour. Attention is paid to the emerging hallmarks, deregulation of cellular energy metabolism and evasion of immune destruction, and enabling characteristics, genome instability and mutation and tumour-promoting inflammation. HNSCC may adapt to hypoxia, suppress HLA expression, and express Toll-like receptors to facilitate inflammation, which support the proliferation of the tumour.

Micellar delivery of cyclopamine and gefitinib for treating pancreatic cancer

Hedgehog (Hh) and epidermal growth factor receptor (EGFR) signaling are involved in pancreatic cancer progression. Targeting these pathways simultaneously with cyclopamine (Hh inhibitor) and gefitinib (EGFR inhibitor) is a promising approach for treating pancreatic cancer. However, the major limitation for effective clinical translation of these molecules is their low aqueous solubility. We have previously demonstrated that methoxy polyethyleneglycol-b-poly(carbonate-co-lactic acid) {mPEG-b-P(CB-co-LA)} copolymer solubilizes hydrophobic anticancer drugs and has the potential to deliver to tumors by an enhanced permeability and retention (EPR) effect. In this study, using the nanoprecipitation method, cyclopamine and gefitinib were efficiently loaded into mPEG-b-P(CB-co-LA) micelles with encapsulation efficiencies of 94.4 and 88.6%, respectively. These micelles had a narrow particle size distribution with a mean particle size of 54.3 nm and a PDI of 0.14. Combination therapy showed a synergistic effect against L3.6pl cells but an additive effect against MIA PaCa-2 cells. Caspase 3/7 activity was also increased when this combination therapy was used, indicating apoptotic cell death. Gene and protein expression analysis indicated cross-talk between Hh and EGFR signaling. Furthermore, the combination decreased tumor growth rate in L3.6pl-derived xenograft mouse tumors. These data suggest the applicability of our micellar system to effectively load and deliver cyclopamine and gefitinib for combination chemotherapy.

Molecular changes in the multistage pathogenesis of head and neck cancer

Head and neck squamous cell carcinomas (SCCHN) arise in the mucosa of the upper aerodigestive tract at multiple anatomic sites. While tobacco and alcohol exposure remain the primary risk factors for this malignancy, infection with the human papilloma virus is emerging as a major contributing factor to cancers that arise primarily in the oropharynx. Despite therapeutic advances, survival has remained relatively unchanged over the past few decades. Increased understand of the cellular and molecular biology of these cancers will improve our understanding of this malignancy and facilitate the development of more effective therapeutic strategies. Alterations that have been studied to date include genetic and epigenetic changes. While the epidermal growth factor receptor (EGFR) is the only established molecular therapeutic target, other proteins and pathways are under active investigation to determine their contribution to SCCHN carcinogenesis and progression.

Coexpression of SGLT1 and EGFR is associated with tumor differentiation in oral squamous cell carcinoma

Overexpression of epidermal growth factor receptor (EGFR) is associated with resistance to chemotherapy and radiotherapy, advanced tumor stage, invasion, metastasis and poor prognosis in malignant tumors. EGFR, therefore, has been an attractive molecular target for chemotherapy. However, the results of clinical studies using inhibitors of its kinase activity have not been promising because the response rates were at most 20%. Sodium-glucose co-transporter 1 (SGLT1) is a membrane protein that mediates the transport of glucose across cellular membranes. EGFR physically associates with and stabilizes SGLT1 to promote glucose uptake into cancer cells through a kinase-independent process. The purpose of this study was to investigate the coexpression of SGLT1 and EGFR and its relationships with clinicopathological features in oral squamous cell carcinoma (OSCC). SGLT1 and EGFR were detected in all OSCC cell lines, and the expression levels of SGLT1 were significantly correlated with those of EGFR. Pearson product-moment correlation coefficient of SGLT1 and EGFR was 0.89 (P = 0.016). The immunohistochemical study using the surgical specimens in 52 patients with tongue SCC also showed a significant correlation between SGLT1 and EGFR. Moreover, SGLT1/EGFR expression was inversely related to tumor differentiation among the 5 clinicopathological factors (P = 0.004). SGLT1/EGFR coexpression might be required in the de-differentiation of OSCC, but further study is needed to clarify the implication of these proteins in the manifestation of malignancy and clinical significance.

Genetic alterations in oral squamous cell carcinoma progression detected by combining array-based comparative genomic hybridization and multiplex ligation-dependent probe amplification

BACKGROUND

Oral squamous cell carcinoma (OSCC), the most common malignancy of the oral cavity, has been shown to occur via a multistep process driven by the accumulation of carcinogen-induced genetic changes.

STUDY DESIGN

Array-based comparative genomic hybridization (aCGH) and multiplex ligation-dependent probe amplification (MLPA) were conducted to screen human genomewide alterations on fresh tissues of the cancer area, the dysplastic transitional area, and the resection margin (normal) free of tumor; these samples were obtained from 7 OSCC patients.

RESULTS

The highest amplification frequencies (100%, 7/7) were detected in FAM5B, TIPARP, PIK3CA, NLGN1, FGF10, HDAC9, GRM3, DDEF1, EDNRB, CHRDL1, and HTR2C, and the highest deletion frequencies in THRAP3, CTTNBP2NL, GATAD2B, REL, CKAP2L, RHOA, EIF4E3, PDLIM5, FBXO3, NEUROD4, and ABCA5 in the OSCC. In the dysplasia, amplification (100%, 7/7) was detected in RNF36 and deletion in CKAP2L and TCF8. We could detect large differences with MLPA in the number of alterations between the cancer or dysplasia versus the normal area with P values of <.001.

CONCLUSION

These findings indicate that these DNA copy number changes on each chromosome in the 3 categories may be associated with OSCC tumorigenesis and/or progression.

Gefitinib in combination with oral topotecan and cyclophosphamide in relapsed neuroblastoma: pharmacological rationale and clinical response

AIM

Activity and toxiciy of gefitinib in combination with topotecan and cyclophosphamide (CPA) were evaluated in a case-series of relapsed neuroblastoma (NB) patients. The in vitro activity of the combination was also assessed.

PROCEDURE

Gefitinib (250 mg/day), topotecan (0.8 mg/m(2)/day), and CPA (50 mg/m(2)/day) (GTC) were administered orally for 14 consecutive days out of 28 days. Antitumor activity of gefitinib as single agent and in combination with either topotecan or CPA was assessed in a panel of NB cell lines.

RESULTS

Ninety-two courses were given in 10 patients. Grade 4 neutropenia was observed in 7/92 courses (8%) and grade 4 thrombocytopenia in 8/92 (9%). Two patients had a grade 2 liver toxicity, four a grade 1/2 skin toxicity, and two a grade 1/2 diarrhea. Dose reduction of topotecan and/or CPA was required in eight patients. After four courses, three patients were in partial response (PR) and four with a stable disease (SD), while three experienced a progressive disease (PD). Time to progression (TTP) was 9 months (range, 1-27). After a median follow-up of 16 months (range 5-54), seven patients are died of disease (DOD) and three alive with disease (AWD). All but one patient discontinued oral chemotherapy because of a PD, whilst one patient stopped chemotherapy after 27 months with a SD. In vitro, gefitinib was synergistic with topotecan and additive with CPA.

CONCLUSION

The GTC combination was well tolerated and the TTP was encouraging. These promising results, also supported by in vitro evidence, should be further confirmed in a phase II study.

Serum proteomic approach for the identification of serum biomarkers contributed by oral squamous cell carcinoma and host tissue microenvironment

The lack of serum biomarkers for head and neck carcinoma limits early diagnosis, monitoring of advanced disease, and prediction of relapses in patients. We conducted a comprehensive proteomics study on serum from mice bearing orthotopic human oral squamous cell carcinomas (OSCC) with distinct invasive phenotypes. Matched established cell lines were transplanted orthotopically into tongues of RAG-2/gamma(c) mice and mouse serum was analyzed by 2-dimensional-differential gel electrophoresis(2D-DIGE)/liquid chromatography (LC)-MS/MS and by online 2D-LC-MS/MS of iTRAQ labeled samples. We identified several serum proteins as being differentially expressed between control and cancer-bearing mice and between noninvasive and invasive cancer (p<0.05). Differentially expressed proteins of human origin included the epidermal growth factor receptor (EGFR), cytokeratins, G-protein coupled receptor 87, Rab11 GTPase, PDZ-domain containing proteins, and PEST-containing nuclear proteins. Identified proteins of mouse origin included clusterin, titin, vitronectin, vitamin D-binding protein, hemopexin, and kininogen I. The levels of serum and cell secreted EGFR were further validated to match proteomic data regarding the inverse correlation with the invasive phenotype. In summary, we report a comprehensive patient-based proteomics approach for the identification of potential serum biomarkers for OSCC using an orthotopic xenograft mouse model.

Src family kinases mediate betel quid-induced oral cancer cell motility and could be a biomarker for early invasion in oral squamous cell carcinoma

Betel quid (BQ)-chewing oral cancer is a prevalent disease in many countries of Southeast Asia. Yet, the precise disease mechanism remains largely unknown. Here, we show that BQ extract-induced cell motility in three oral cancer cells (Ca9-22, SAS, and SCC9) presumably involves the Src family kinases (SFKs). Besides, BQ extract can markedly induce cell migration of wild type mouse embryonic fibroblasts (MEFs) but not MEFs lacking three SFK members, namely, Src, Yes, and Fyn, indicating the requirement of SFKs for BQ-induced cell motility. Betel quid extract can also elevate cellular SFK activities because phosphorylation of tyrosine 416 at the catalytic domain is increased, which in turn promotes phosphorylation of an in vitro substrate, enolase. Furthermore, we identified that areca nut, a major component of BQ, is the key factor accounting for BQ-induced cell migration and invasion through SFKs-mediated signaling pathways. Immunohistochemistry revealed that, particularly in BQ-chewing cases, the activity of SFKs was significantly higher in tumor-adjacent mucosa than that in solid tumor areas (P < .01). These results suggest a possible role of SFKs in tumor-host interface and thus in early tumor invasion in vivo. Consistent with this is the observation that activation of SFKs is colocalized with invasive tumor fronts in oral squamous cell carcinoma. Together, we conclude that SFKs may represent a potential biomarker of invasion and therapeutic target in BQ-induced oral cancer.

Basic evidence of molecular targeted therapy for oral cancer and salivary gland cancer

BACKGROUND

Recently, attention has been focused on molecular targeted cancer therapy in various tumors. Although there is no single consistent molecular target specific for oral squamous cell carcinoma (OSCC) and salivary gland cancer (SGC), there are a number of promising candidate proteins. The aim of this review is to introduce the basic evidences to support the molecular targeting for OSCC and SGC.

METHODS

We focused on the 4 molecules, epidermal growth factor receptor (EGFR), cyclooxygenase-2 (COX-2), peroxisome proliferator-activated receptor gamma (PPARgamma), and progesterone receptor, that are, respectively, associated with the proliferation and the differentiation of OSCC and SGC.

RESULTS

Gefitinib ("Iressa," ZD1839), a small molecule EGFR tyrosine kinase inhibitor, can inhibit the proliferation of OSCC cell lines in a dose- and time-dependent manner and lead to cell cycle arrest with accumulation of cells in the G1 phase, and a decrease of cells in S phase. The agent suppressed tumor metastasis in the animal model. Furthermore, a cooperative antiproliferative effect was obtained when cancer cells were treated with radiation followed by gefitinib. While radiation alone did not significantly affect p38 mitogen-activated protein kinase and MAP kinase kinase (MEK)1/2 autophosphorylation, the combination of gefitinib and radiation completely inhibited the downstream signaling of EGFR. Gefitinib enhanced tumor radioresponsiveness by multiple mechanisms, including the growth inhibition and effects on DNA repair after exposure to radiation. Next, the level of COX-2 expression correlated inversely with increased tumor radiation sensitivity. Treatment with celecoxib, a COX-2 selective inhibitor, enhanced the radioresponsiveness of HSC-2 cells, which constitutively expressed COX-2. Another promising molecular target is the PPARgamma, which is a member of the nuclear receptor superfamily of ligand-activated transcription factors. Recent studies have demonstrated that PPARgamma ligands induce cellular differentiation and inhibit cell growth in carcinomas of various types. These data suggest that synthetic PPARgamma ligands may be useful for molecular targeting of oral cancer. Finally, the possibility of using molecular targeted therapy directed at hormone receptors in the treatment of advanced SGCs was described.

CONCLUSION

The basic data strongly suggested the possibility of tumor suppression by targeting these molecules. Studies of different targeted agents alone or with more conventional treatment modalities are needed to fully determine what role the targeted therapy will play in the management of patients with OSCC and SGC.

Bypassing cellular EGF receptor dependence through epithelial-to-mesenchymal-like transitions

Over 90% of all cancers are carcinomas, malignancies derived from cells of epithelial origin. As carcinomas progress, these tumors may lose epithelial morphology and acquire mesenchymal characteristics which contribute to metastatic potential. An epithelial-to-mesenchymal transition (EMT) similar to the process critical for embryonic development is thought to be an important mechanism for promoting cancer invasion and metastasis. Epithelial-to-mesenchymal transitions have been induced in vitro by transient or unregulated activation of receptor tyrosine kinase signaling pathways, oncogene signaling and disruption of homotypic cell adhesion. These cellular models attempt to mimic the complexity of human carcinomas which respond to autocrine and paracrine signals from both the tumor and its microenvironment. Activation of the epidermal growth factor receptor (EGFR) has been implicated in the neoplastic transformation of solid tumors and overexpression of EGFR has been shown to correlate with poor survival. Notably, epithelial tumor cells have been shown to be significantly more sensitive to EGFR inhibitors than tumor cells which have undergone an EMT-like transition and acquired mesenchymal characteristics, including non-small cell lung (NSCLC), head and neck (HN), bladder, colorectal, pancreas and breast carcinomas. EGFR blockade has also been shown to inhibit cellular migration, suggesting a role for EGFR inhibitors in the control of metastasis. The interaction between EGFR and the multiple signaling nodes which regulate EMT suggest that the combination of an EGFR inhibitor and other molecular targeted agents may offer a novel approach to controlling metastasis.

Prolonged response to oral gefitinib, cyclophosphamide, and topotecan in heavily pretreated relapsed stage 4 neuroblastoma: a case report

A girl with metastatic neuroblastoma diagnosed at 4 years of age experienced an early disseminated relapse after high-dose chemotherapy. After reinduction, compassionate treatment with gefitinib (250 mg/d fixed dose) with oral topotecan (0.8 mg/m(2)/d) and cyclophosphamide (50 mg/m(2)/d) for 14 consecutive days, each course repeated every 28 days, was administered. Complete marrow clearance and metaiodobenzylguanidine response were achieved after 4 courses. After the first course, topotecan and cyclophosphamide were reduced by 25% for grade 4 hematologic toxicity. Subsequent courses were well tolerated. The girl remained progression free for 27 months. This combination may represent a viable therapeutic option and deserves further evaluation in resistant neuroblastoma.

Epidermal growth factor receptor cooperates with signal transducer and activator of transcription 3 to induce epithelial-mesenchymal transition in cancer cells via up-regulation of TWIST gene expression

Aberrant epidermal growth factor receptor (EGFR) signaling is a major cause of tumor progression and metastasis; the underlying mechanisms, however, are not well understood. In particular, it remains elusive whether deregulated EGFR pathway is involved in epithelial-mesenchymal transition (EMT), an early event that occurs during metastasis of cancers of an epithelial origin. Here, we show that EGF induces EGFR-expressing cancer cells to undergo a transition from the epithelial to the spindle-like mesenchymal morphology. EGF reduced E-cadherin expression and increased that of mesenchymal proteins. In search of a downstream mediator that may account for EGF-induced EMT, we focused on transcription repressors of E-cadherin, TWIST, SLUG, and Snail and found that cancer cells express high levels of TWIST and that EGF enhances its expression. EGF significantly increases TWIST transcripts and protein in EGFR-expressing lines. Forced expression of EGFR reactivates TWIST expression in EGFR-null cells. TWIST expression is suppressed by EGFR and Janus-activated kinase (JAK)/signal transducer and activator of transcription 3 (STAT3) inhibitors, but not significantly by those targeting phosphoinositide-3 kinase and MEK/ERK. Furthermore, constitutively active STAT3 significantly activates the TWIST promoter, whereas the JAK/STAT3 inhibitor and dominant-negative STAT3 suppressed TWIST promoter. Deletion/mutation studies further show that a 26-bp promoter region contains putative STAT3 elements required for the EGF-responsiveness of the TWIST promoter. Chromatin immunoprecipitation assays further show that EGF induces binding of nuclear STAT3 to the TWIST promoter. Immunohistochemical analysis of 130 primary breast carcinomas indicates positive correlations between non-nuclear EGFR and TWIST and between phosphorylated STAT3 and TWIST. Together, we report here that EGF/EGFR signaling pathways induce cancer cell EMT via STAT3-mediated TWIST gene expression.

Focal adhesion kinase: a promising target for anticancer therapy

Focal adhesion kinase (FAK) is a protein tyrosine kinase acting as an early modulator of the integrin signalling cascade, thus regulating various basic cellular functions. In transformed cells, upregulation of FAK protein expression and uncontroled signalling were held responsible for the promotion of malignant phenotypic characteristics, as well as resistance to chemotherapy and radiotherapy. Direct FAK targeting resulted in the inhibition of the malignant phenotype of cancer cells, whereas increased apoptotic rates of cancer cells, either used alone or in combination with conventional chemotherapeutic agents, radiotherapy or hormonal therapy. Furthermore, drugs used in cancer chemotherapy, besides their basic mode of action, were also shown to act through altering FAK signalling. Finally, positive results were noted by the transfection of cancer cells with fak mutants or genes that suppress FAK expression or activity, such as phosphatase and tensin homolog deleted on chromosome Ten (PTEN), ribonucleotide reductase M1 polypeptide (RRM1) and melanoma differentiation-associated gene-7 (mda-7). The purpose of this article is a comprehensive review of the existing data on the possible use of FAK targeting in anticancer therapy.

Cell adhesion molecules, the extracellular matrix and oral squamous carcinoma

Carcinomas are characterized by invasion of malignant cells into the underlying connective tissue and migration of malignant cells to form metastases at distant sites. These processes require alterations in cell-cell and cell-extracellular matrix interactions. As cell adhesion molecules play a role in cell-cell and cell-extracellular matrix adhesion and interactions they are involved in the process of tumour invasion and metastases. In epithelial tissues, receptors of the integrin family mediate adhesion to the adjacent matrix whereas cadherins largely mediate intercellular adhesion. These and other cell adhesion molecules such as intercellular adhesion molecule-1, CD44, dystroglycans and selectins, are involved and undergo changes in carcinomas, which provide possible targets for anti-cancer drug treatments. In the extracellular matrix that is associated with tumours, laminin 5, oncofetal fibronectin and tenascin C appear. The degree of expression of some of these moieties indicates prognosis in oral cancer and offer targets for antibody-directed radiotherapy. Metalloproteases which degrade the extracellular matrix are increased in carcinomas, and their activity is necessary for tumour angiogenesis and consequent invasion and metastases. Metalloprotease inhibitors have begun to produce decreases in mortality in clinical trials. This report provides a brief overview of our current understanding of cell adhesion molecules, the extracellular matrix, tumour invasion and metastasis.

Sensing radiosensitivity of human epidermal stem cells

PURPOSE

Radiosensitivity of stem cells is a matter of debate. For mouse somatic stem cells, both radiosensitive and radioresistant stem cells have been described. By contrast, the response of human stem cells to radiation has been poorly studied. As epidermis is a radiosensitive tissue, we evaluated in the present work the radiosensitivity of cell populations enriched for epithelial stem cells of human epidermis.

METHODS AND MATERIALS

The total keratinocyte population was enzymatically isolated from normal human skin. We used flow cytometry and antibodies against cell surface markers to isolate basal cell populations from human foreskin. Cell survival was measured after a dose of 2Gy with the XTT assay at 72h after exposure and with a clonogenic assay at 2 weeks. Transcriptome analysis using oligonucleotide microarrays was performed to assess the genomic cell responses to radiation.

RESULTS

Cell sorting based on two membrane proteins, alpha6 integrin and the transferrin receptor CD71, allowed isolation of keratinocyte populations enriched for the two types of cells found in the basal layer of epidermis: stem cells and progenitors. Both the XTT assay and the clonogenic assay showed that the stem cells were radioresistant whereas the progenitors were radiosensitive. We made the hypothesis that upstream DNA damage signalling might be different in the stem cells and used microarray technology to test this hypothesis. The stem cells exhibited a much more reduced gene response to a dose of 2Gy than the progenitors, as we found that 6% of the spotted genes were regulated in the stem cells and 20% in the progenitors. Using Ingenuity Pathway Analysis software, we found that radiation exposure induced very specific pathways in the stem cells. The most striking responses were the repression of a network of genes involved in apoptosis and the induction of a network of cytokines and growth factors.

CONCLUSION

These results show for the first time that keratinocyte populations enriched for stem cells from human epidermis are radioresistant. Based on both repressed and induced genes, we found that the major response of the irradiated stem cell population was the regulation of genes functionally related to cell death, cell survival and apoptosis.

Advances in the biology of oral cancer

The incidence of oral cancer remains high and is associated with many deaths in both Western and Asian countries. Several risk factors for the development of oral cancer are now well known, including smoking, drinking and consumption of smokeless tobacco products. Genetic predisposition to oral cancer has been found in certain cases but its components are not yet entirely clear. In accordance with the multi-step theory of carcinogenesis, the natural history of oral cancer seems to gradually evolve through transitional precursor lesions from normal epithelium to a full-blown metastatic phenotype. A number of genomic lesions accompany this transformation and a wealth of related results has appeared in recent literature and is being summarized here. Furthermore, several key genes have been implicated, especially well-known tumor suppressors like the cyclin-dependent kinase inhibitors, TP53 and RB1 and oncogenes like the cyclin family, EGFR and ras. Viral infections, particularly with oncogenic HPV subtypes and EBV, can have a tumorigenic effect on oral epithelia and their role is discussed, along with potential therapeutic interventions. A brief explanatory theoretical model of oral carcinogenesis is provided and potential avenues for further research are highlighted.

Emodin inhibits tumor cell adhesion through disruption of the membrane lipid Raft-associated integrin signaling pathway

Cell adhesion and spreading is a crucial step in the metastatic cascade of cancer cells, and interruption of this step is considered to be a logical strategy for prevention and treatment of tumor metastasis. Emodin is the major active component of the rhizome of Rheum palmatum L., with known anticancer activities. Here, we first found that emodin significantly inhibited cell adhesion of various human cancer cells. This inhibition was achieved through suppressing the recruitment of focal adhesion kinase (FAK) to integrin beta(1) as well as the phosphorylation of FAK followed by the decreased formation of focal adhesion complex (FAC). In understanding the underlying mechanisms, we found that emodin inhibited the lipid raft clustering and subsequent colocalization of integrin beta(1) and FAC proteins within lipid rafts. Lipid profile analysis revealed significant decrease of cholesterol and sphingolipids in raft fraction after emodin treatment. Cholesterol replenishment abolished the adverse effect of emodin on the translocation of integrin beta(1) and FAC proteins into the lipid raft fraction and cell adhesion. Therefore, data from this study provide novel evidence that emodin inhibits cell adhesion and spreading through disruption of the membrane lipid raft-associated integrin signaling pathway.

Molecular biology of epidermal growth factor receptor inhibition for cancer therapy

Understanding the role of the epidermal growth factor receptor (EGFR) in cellular signalling processes underlying malignancy has enabled the development of rationally designed EGFR-targeted therapeutics. Strategies have been devised to interfere with the EGFR signalling at three different levels: at the extracellular level, competing with ligand binding; at the intracellular level, inhibiting the activation of the tyrosine kinase; or at the mRNA level, modulating the expression of the EGFR protein. Each of these strategies has proven to have an antitumour effect mediated by events such as inhibition of cell proliferation, induction of apoptosis, decrease of cellular invasion and migration; and/or inhibition of angiogenesis. Furthermore, the combination of these strategies with traditional chemotherapy or radiotherapy has generally resulted in enhanced antitumour effects. Likewise, the benefit of interfering simultaneously with different signalling pathways has been documented to improve tumour growth inhibition. These preclinical results have encouraged clinical studies that led to the FDA approval of three drugs. However, finding the perfect strategy for each individual patient appears to be a limiting factor, demanding further research to be able to generate relevant molecular expression profiles on a case-to-case basis. Taken together, a successful EGFR inhibition will require a better understanding of signalling pathways in combination with the development of rationally designed effective molecules.

Molecular mediators of metastasis in head and neck squamous cell carcinoma

BACKGROUND

The presence of regional metastasis in patients with head and neck squamous cell carcinoma (HNSCC) is a common and adverse event associated with poor prognosis and high mortality. Although significant improvements in standard therapies have increased the efficacy of local tumor management, the high incidence of tumor recurrence has resulted in limited improvements in overall survival rates. Understanding the molecular mechanisms that mediate HNSCC invasion and metastasis may enable identification of novel therapeutic targets for the prevention and management of tumor dissemination.

METHODS

A literature review was performed.

RESULTS

Several biologic mediators and mechanisms that have been implicated in HNSCC metastasis, such as cell adhesion molecules, proteolytic enzymes, growth factor signaling, metastasis suppressor genes, and chemokine receptors were reviewed.

CONCLUSIONS

Prevention of HNSCC metastasis is an important clinical objective that requires an increased understanding of the molecular mechanisms of tumor invasion and dissemination.

Gefitinib (ZD1839, Iressa) as palliative treatment in recurrent or metastatic head and neck cancer

To assess the level of activity and toxicity of gefitinib (ZD1839, Iressa™) in a population of patients with locally recurrent and/or metastatic head and neck cancer. Patients were recruited into an expanded access programme through the multidisciplinary head and neck clinics at the Royal Marsden and St George's Hospitals. Patients were required to have received at least one course of standard systemic chemotherapy or radiation therapy, or be medically unfit for chemotherapy. Patients were commenced on single-agent gefitinib at a dose of 500 mg day⁻¹. Clinical, symptomatic and radiological response, time to progression (TTP), survival and toxicity were recorded. A total of 47 patients were enrolled (35 male and 12 female) with a median age of 62 years (range 18–93 years). The observed clinical response rate was 8% with a disease control rate (complete response, partial response, stable disease) of 36%. In all, 34% of patients experienced an improvement in their symptoms. The median TTP and survival were 2.6 and 4.3 months, respectively. Acneiform folliculitis was the most frequent toxicity observed (76%) but the majority of cases were grade 1 or 2. Only four patients experienced grade 3 toxicity of any type (all cases of folliculitis). Gefitinib was well tolerated and yielded symptomatic improvement in one-third of patients. However, this agent appeared to possess limited antitumour activity in this group of patients with head and neck cancer in whom the objective response rate, median TTP and survival were all lower than has been reported in a previous study.

Future Directions in the Treatment of Oral Cancer

Future developments in the realms of nanotechnology and directed therapeutics will alter the diagnosis and treatment of oral cancer relative to contemporary treatment modalities. Continued experience and investigation will determine the clinical usefulness of the various technologies that have been described in this article.

Interaction between epidermal growth factor receptor– and cyclooxygenase 2–mediated pathways and its implications for the chemoprevention of head and neck cancer

Head and neck squamous cell carcinoma is a well-known model for chemoprevention studies because of its field cancerization effect, its multistep carcinogenesis process, and the easy accessibility of biopsies to target lesions. With new understandings of head and neck carcinogenesis and the development of molecular targeted therapy, chemoprevention trials for head and neck squamous cell carcinoma have been rapidly updated. Cyclooxygenase-2 (COX-2) and epidermal growth factor receptor (EGFR) tyrosine kinase inhibitors are gaining significant attention as potential chemopreventive agents. Both COX-2 and EGFR are involved in head and neck carcinogenesis. Targeting COX-2 and EGFR separately has shown promising antitumor activity. Recently, combinations of COX-2 and EGFR tyrosine kinase inhibitors have been reported to show synergistic/additive effects in preclinical studies. Because COX-2 and EGFR tyrosine kinase inhibitors are toxic as single agents in clinical trials, the combination of COX-2 and EGFR tyrosine kinase inhibitors used at lower doses seems more promising than monotherapy with either as a novel strategy in head and neck cancer chemoprevention.

Biological significance of c-erbB family oncogenes in head and neck cancer

Squamous cell carcinoma of the head and neck (SCCHN) tends to run an aggressive course and the prognosis has remained virtually unchanged in recent decades. The development of novel therapeutic strategies to improve patient outcome centres on the biology of the disease, namely the pivotal c-erbB family of growth factor receptors. c-erbB1 (or epidermal growth factor receptor, EGFR), is key to the pathogenesis of SCCHN and plays a central role in a complex network of downstream integrated signalling pathways. EGFR overexpression, detected in up to 90% of SCCHN, correlates with an increased risk of locoregional tumour relapse following primary therapy and relative resistance to treatment. The biological sequelae of erbB receptor activation are not simply cell proliferation, but also inhibition of apoptosis, enhanced migration, invasion, angiogenesis and metastasis: the 'hallmarks of cancer' [1]. As EGFR overexpression is associated with a poor clinical outcome in SCCHN, this receptor is attractive as a therapeutic target and the successful development of targeted therapies represents a paradigm shift in the medical approach to head and neck cancer. However, the extensive cross talk between signalling pathways, the multiple molecular aberrations and genetic plasticity in SCCHN all contribute to inherent and acquired resistance to both conventional and novel therapies. Understanding the cancer cell biology, in particular the significance of co-expression of c-erbB (and other) receptors, and the cell survival stimuli from (for example) activation of the phosphoinositide 3-kinase (PI3-kinase) cascade is fundamental to overcome current limitations in biologically targeted therapies.

Why do patients with head and neck squamous cell carcinoma experience distant metastases: can they be prevented?

PURPOSE OF REVIEW

This article will examine recent publications that enhance our understanding of this process, and current areas of investigation for therapeutic intervention in preventing and treating metastatic disease.

RECENT FINDINGS

Recent investigations have led to insights into the mechanisms of cellular adhesion, invasion, and angiogenesis. E-cadherin, integrins, and selectins are all pivotal in cell-cell adhesion and communication. Recent advances in the area of tumor angiogenesis have led to our discovery of endostatin, an anti-angiogenic peptide that has potential in treating metastatic head and neck cancer. Current trials looking at sentinel node mapping may allow us to evaluate the nodal status of early head and neck cancer and identify a subset of patients at risk for distant metastasis.

SUMMARY

As our understanding of metastatic disease increases, so will our ability to intervene in the various pathways involved in metastatic evolution. Metastatic cells are likely to respond differently to chemotherapeutic agents. Agents inhibiting specific aspects of invasion, adhesion, and angiogenesis will need to be combined to intervene at these key steps. Continued investigation into the biology of the epidermal growth factor receptor has led to an increased understanding of the mechanisms of abrogation of apoptosis, increased cellular motility, and metastasis. Inhibition of the epidermal growth factor receptor pathway with the monoclonal antibody C-255 has been shown to inhibit these processes and will likely be effective in reducing the development of distant metastasis.

Evaluation of the therapeutic potential of the epidermal growth factor receptor tyrosine kinase inhibitor gefitinib in preclinical models of bladder cancer

The epidermal growth factor receptor (EGFR) is associated with aggressive phenotypes and is an independent predictor of stage progression and mortality in bladder cancer. Gefitinib ('Iressa,' ZD1839) is an orally active EGFR-tyrosine kinase inhibitor. The objective of this study was to evaluate the in vitro and in vivo effects of gefitinib in the EGFR-expressing human bladder cancer cell lines 253J B-V, RT-112, and T24. EGFR expression was 3- and 2-fold higher in 253J B-V and RT-112, respectively, compared with T24 cells. Ten microm gefitinib inhibited EGFR, p42/44 extracellular signal-regulated kinase (ERK), and Akt/protein kinase B phosphorylation in all three of the cell lines. Inhibition of ERK by gefitinib was significantly greater in 253J B-V compared with RT-112 and T24 cells (9:2:1 in 253J B-V:RT-112:T24), whereas inhibition of Akt phosphorylation was less in 253J B-V compared with RT-112 and T24 cells (1:9:30 in 253J B-V:RT-112:T24). When cultured in serum-free medium supplemented with epidermal growth factor, 10 microm gefitinib inhibited DNA synthesis in T24 and RT-112 cells, whereas 1 microm gefitinib was sufficient to inhibit DNA synthesis in 253J B-V cells. Similarly, in the presence of serum, 10 microm gefitinib induced a significant reduction in S-phase and viable cell number in T24 and RT-112 cells, whereas 1-10 microm gefitinib caused a dose-dependent effect on these phenotypes in 253J B-V cells. Gefitinib significantly enhanced the ability of ionizing radiation to reduce colony forming ability in 253J B-V and RT-112 cells. In nude mice, a daily oral dose of 150 mg/kg gefitinib induced regression of tumors produced by 253J B-V cells growing at s.c. sites and suppression of tumors produced by these cells at orthotopic sites but had no effect on tumors produced by RT-112 cells growing at s.c. sites. The data indicates that gefitinib has potential therapeutic value, alone or in combination with ionizing radiation, in a subset of EGFR-expressing bladder cancers. However, there is a differential response to gefitinib in these EGFR-expressing bladder cancer cell lines. Although gefitinib can inhibit phosphorylation of EGFR, ERK, and Akt, and inhibit growth of bladder cancer cells in vitro, it does not necessarily inhibit growth of bladder cancer cells in vivo. It is likely that optimized therapy approaches will require an accurate "molecular" diagnosis allowing effective, selective, tailored therapeutic strategies to be designed.