EGFR protein overexpression and mutation in areca quid-associated oral cavity squamous cell carcinoma in Taiwan

PDZ-binding kinase inhibitor OTS514 suppresses the proliferation of oral squamous carcinoma cells

OBJECTIVE

PDZ-binding kinase (PBK) has been reported as a poor prognostic factor and is a promising molecular target for anticancer therapeutics. Here, we aimed to investigate the effect of specific PBK inhibitor OTS514 on the survival of OSCC cells.

METHODS

Four OSCC cell lines (HSC-2, HSC-3, SAS, and OSC-19) were used to examine the effect of OTS514 on cell survival and apoptosis. DNA microarray analysis was conducted to investigate the effect of OTS514 on gene expression in OSCC cells. Gene set enrichment analysis was performed to identify molecular signatures related to the antiproliferative effect of OTS514.

RESULTS

OTS514 decreased the cell survival of OSCC cells dose-dependently, and administration of OTS514 readily suppressed the HSC-2-derived tumor growth in immunodeficient mice. Treatment with OTS514 significantly increased the number of apoptotic cells and caspase-3/7 activity. Importantly, OTS514 suppressed the expression of E2F target genes with a marked decrease in protein levels of E2F1, a transcriptional factor. Moreover, TP53 knockdown attenuated OTS514-induced apoptosis.

CONCLUSION

OTS514 suppressed the proliferation of OSCC cells by downregulating the expression of E2F target genes and induced apoptosis by mediating the p53 signaling pathway. These results highlight the clinical application of PBK inhibitors in the development of molecular-targeted therapeutics against OSCC.

Inhibition of VEGFR2 and EGFR signaling cooperatively suppresses the proliferation of oral squamous cell carcinoma

BACKGROUND

Epidermal growth factor receptor (EGFR) is frequently overexpressed in oral squamous cell carcinoma (OSCC), and EGFR-targeting therapeutics have been widely employed to treat patients with a variety of carcinomas including OSCC. Here, we aimed to investigate alternative signaling for OSCC survival under the disruption of EGFR signaling.

METHODS

OSCC cell lines, namely HSC-3 and SAS, were utilized to investigate how EGFR disruption affects cell proliferation. Gene set enrichment analysis was performed to examine how EGFR disruption affects oncogenic signaling in OSCC cells. Disruption of KDR gene was performed using CRISPR/Cas9 techniques. A VEGFR inhibitor, vatalanib was used to research the impact of VEGFR inhibition on OSCC survival.

RESULTS

EGFR disruption significantly decreased the proliferation and oncogenic signaling including Myc and PI3K-Akt, in OSCC cells. Chemical library screening assays revealed that VEGFR inhibitors continued to inhibit the proliferation of EGFR-deficient OSCC cells. In addition, CRISPR-mediated disruption of KDR/VEGFR2 retarded OSCC cell proliferation. Furthermore, combined erlotinib-vatalanib treatment exhibited a more potent anti-proliferative effect on OSCC cells, compared to either monotherapy. The combined therapy effectively suppressed the phosphorylation levels of Akt but not p44/42.

CONCLUSION

VEGFR-mediated signaling would be an alternative signaling pathway for the survival of OSCC cells under the disruption of EGFR signaling. These results highlight the clinical application of VEGFR inhibitors in the development of multi-molecular-targeted therapeutics against OSCC.

CAR-T cells targeting HLA-G as potent therapeutic strategy for EGFR-mutated and overexpressed oral cancer

Oral squamous cell carcinoma (OSCC) is a common malignancy in the world. Recently, scientists have focused on therapeutic strategies to determine the regulation of tumors and design molecules for specific targets. Some studies have demonstrated the clinical significance of human leukocyte antigen G (HLA-G) in malignancy and NLR family pyrin domain-containing 3 (NLRP3) inflammasome in promoting tumorigenesis in OSCC. This is the first study to investigate whether aberrant epidermal growth factor receptor (EGFR) induces HLA-G expression through NLRP3 inflammasome-mediated IL-1β secretion in OSCC. Our results showed that the upregulation of NLRP3 inflammasome leads to abundant HLA-G in the cytoplasm and cell membrane of FaDu cells. In addition, we also generated anti-HLA-G chimeric antigen receptor (CAR)-T cells and provided evidence for their effects in EGFR-mutated and overexpressed oral cancer. Our results may be integrated with OSCC patient data to translate basic research into clinical significance and may lead to novel EGFR-aberrant OSCC treatment.

Silencing DNA Polymerase β Induces Aneuploidy as a Biomarker of Poor Prognosis in Oral Squamous Cell Cancer

Most patients with oral squamous cell cancer (OSCC) have a locally advanced stage at diagnosis. The treatment strategies are diverse, including surgery, radiotherapy and chemotherapy. Despite multimodality treatment, the response rate is unsatisfactory. DNA repair and genetic instability are highly associated with carcinogenesis and treatment outcomes in oral squamous cell cancer, affecting cell growth and proliferation. Therefore, focusing on DNA repair and genetic instability interactions could be a potential target for improving the outcomes of OSCC patients. DNA polymerase-β (POLB) is an important enzyme in base excision repair and contributes to gene instability, leading to tumorigenesis and cancer metastasis. The aim of our study was to confirm POLB regulates the growth of OSCC cells through modulation of cell cycle and chromosomal instability. We analyzed a tissue array from 133 OSCC patients and discovered that low POLB expression was associated with advanced tumor stage and poor overall survival. In multivariate Cox proportional hazards regression analysis, low POLB expression and advanced lymph node status were significantly associated with poor survival. By performing in vitro studies on model cell lines, we demonstrated that POLB silencing regulated cell cycles, exacerbated mitotic abnormalities and enhanced cell proliferation. After POLB depletion, OSCC cells showed chromosomal instability and aneuploidy. Thus, POLB is an important maintainer of karyotypic stability in OSCC cells.

Secreted amphiregulin promotes vincristine resistance in oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is the most common type of oral cancer. Despite advances in surgery, radiotherapy and chemotherapy, the overall 5‑year survival rate of patients with OSCC has not significantly improved. In addition, the prognosis of patients with advanced‑stage OSCC remains poor. Therefore, it is necessary to develop novel therapeutic modalities. Vincristine (VCR), a naturally occurring vinca alkaloid, is a classical microtubule‑destabilizing agent and is widely used in the treatment of a number of cancers. Despite the proven antitumor benefits of VCR treatment, one of the major reasons for the failure of treatment is drug resistance. Changes in the tumor microenvironment are responsible for cross‑talk between cells, which may facilitate drug resistance in cancers; secreted proteins may promote communication between cancer cells to induce the development of resistance. To identify the secreted proteins involved in VCR resistance, conditioned media was obtained, and an antibody array was conducted to screen a comprehensive secretion profile between VCR‑resistant (SAS‑VCR) and parental (SAS) OSCC cell lines. The results showed that amphiregulin (AREG) was highly expressed and secreted in SAS‑VCR cells. Pretreatment with exogenous recombinant AREG markedly increased drug resistance against VCR in OSCC cells, as assessed by an MTT assay. Colony formation, MTT and western blot assays were performed to investigate the effects of AREG knockdown on VCR sensitivity. The results indicated that AREG expression can regulate VCR resistance in OSCC cells; overexpression of AREG increased VCR resistance in parental cells, whereas AREG knockdown decreased the VCR resistance of resistant cells. In addition, it was also demonstrated that the glycogen synthase kinase‑3β pathway may be involved in AREG‑induced VCR resistance. These findings may provide rationale to combine VCR with blockade of AREG‑related pathways for the effective treatment of OSCC.

EGFR copy number alterations in primary tumors, metastatic lymph nodes, and recurrent and multiple primary tumors in oral cavity squamous cell carcinoma

Background

The EGFR and downstream signaling pathways play an important role in tumorigenesis in oral squamous cell carcinoma (OSCC). Gene copy number alteration is one mechanism for overexpressing the EGFR protein and was also demonstrated to be related to lymph node metastasis, tumor invasiveness and perineural invasion. Therefore, we hypothesized that EGFR gene copy number alteration in the primary tumor could predict amplification in recurrent tumors, lymph node metastatic foci or secondary primary tumors.

Methods

We recruited a group of newly diagnosed OSCC patients (n = 170) between Mar 1997 and Jul 2004. Metastatic lymph nodes were identified from neck dissection specimens (n = 57). During follow-up, recurrent lesions (n = 41) and secondary primary tumors (SPTs, n = 17) were identified and biopsied. The EGFR gene amplifications were evaluated by fluorescence in situ hybridization (FISH) assay in primary tumors, metastatic lymph nodes, recurrences and SPTs.

Results

Of the 170 primary OSCCs, FISH showed low EGFR amplification/polysomy in 19 (11.4%) patients and amplification in 33 (19.8%) patients. EGFR gene amplification was related to lymph node metastasis (χ2 trend test: p = 0.018). Of 57 metastatic lymph nodes, nine (15.8%) had EGFR polysomy and 14 (24.6%) had EGFR gene amplification. The concordance rate of EGFR gene copy number in primary tumors and lymph node metastasis was 68.4% (McNemar test: p = 0.389). Of 41 recurrent tumors, five (12.2%) had EGFR polysomy and five (12.2%) had gene amplification. The concordance rate of EGFR gene copy number between primary tumors and recurring tumors was 65.9% (McNemar test: p = 0.510). The concordance rate between primary tumors and SPTs was 70.6%. EGFR amplification in either primary tumors, metastatic lymph nodes or recurrent tumors had no influence on patient survival.

Conclusion

We can predict two-thirds of the EGFR gene copy number alterations in lymph node metastasis or recurrent tumors from the analysis of primary tumors. For OSCC patients who are unable to provide lymph node or recurrent tumor samples for EGFR gene copy number analysis, examining primary tumors could provide EGFR clonal information in metastatic, recurrent or SPT lesions.

Electronic supplementary material

The online version of this article (10.1186/s12885-017-3586-9) contains supplementary material, which is available to authorized users.

Epidermal growth factor receptor intron-1 CA repeat polymorphism on protein expression and clinical outcome in Taiwanese oral squamous cell carcinoma

This study was designed to explore the relationship between epidermal growth factor receptor (EGFR) CA repeats polymorphism and protein expression in oral cavity squamous cell carcinoma (OSCC). A total of 194 OSCCs were examined for EGFR protein overexpression, gene copy number and the length of their CA repeats. The length of the EGFR CA repeats was found not to be associated with EGFR gene copy number or with protein overexpression. To exclude the effect of EGFR gene copy number on protein overexpression, only those OSCC tumors with disomy of the EGFR gene were included in further analysis. In this subgroup, EGFR protein overexpression was significantly associated with poor differentiation of the tumor cells and lymph node metastasis, especially extra-capsular spread. However, EGFR CA repeats were not related to any clinicopathological factor. Interestingly, patients genetically found to have the EGFR CA repeats SS genotype and having tumors with EGFR protein overexpression were found to have a worst prognosis in terms of disease-free survival (DFS) (HR = 2.68; 95% CI, 1.03-6.98) after multivariate adjustment. The present study demonstrates that concurrent overexpression of EGFR protein in the presence genetically of the SS form CA repeats acts as a predictor for poor DFS.

Prevalence of EGFR Tyrosine Kinase Domain Mutations in Head and Neck Squamous Cell Carcinoma: Cohort Study and Systematic Review

BACKGROUND

Mutations in the epidermal growth factor receptor (EGFR) tyrosine kinase domain (TKD) are associated with response and resistance to targeted therapy. The EGFR mutation status in patients with advanced oral and oropharyngeal squamous cell carcinoma (OOSCC) was evaluated. A systematic literature review was undertaken to summarize current evidence and estimate the overall prevalence of EGFR TKD mutations in patients with head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

Genomic DNA was extracted from formalin-fixed, paraffin-embedded tumor samples of 113 patients with OOSCC. Pyrosequencing was performed to investigate mutations in EGFR exons 18 to 21. Medline databases were searched for relevant studies. Studies reporting mutations in the EGFR TKD in HNSCC were eligible for inclusion in the systematic review.

RESULTS

No mutations in the EGFR TKD were observed in 113 samples of OOSCC. A total of 53 eligible studies were included in the systematic review. In total, from the review, 117 patients harboring a total of 159 EGFR TKD mutations were reported among 4122 patients with HNSCC. The overall prevalence of EGFR TKD mutations in HNSCC was 2.8%.

CONCLUSION

Large-scale studies are warranted to provide further evidence regarding the mutation status of EGFR in patients with HNSCC.

Lack of mutations in protein tyrosine kinase domain coding exons 19 and 21 of the EGFR gene in oral squamous cell carcinomas

BACKGROUND

The epidermal growth factor receptor (EGFR) plays a vital role in the activation and inactivation of receptor tyrosine kinases. Mutations in exons 19 and 21 of EGFR are commonly found to be associated with non small cell lung carcinoma and triple negative breast cancer, enhancing sensitivity to EGFR targeting chemotherapeutic agents. Since amplification and prolonged activation of EGFR molecules have been identified in oral squamous cell carcinomas (OSCC), we investigated whether OSCCs carried mutations in exons 19 and 21 of EGFR to their incidence.

MATERIALS AND METHODS

Tumor chromosomal DNA isolated from forty surgically excised oral squamous cell carcinoma tissues was subjected to PCR amplification with intronic primers flanking exons 19 and 21 of the EGFR gene. The PCR amplicons were subsequently subjected to direct sequencing to elucidate the mutation status.

RESULTS

Data analysis of the EGFR exon 19 and 21 coding sequences did not show any mutations in the forty OSCC samples that were analyzed.

CONCLUSIONS

To the best of our knowledge, this is the first study to have investigated the genetic status of exons 19 and 21 of EGFR in Indian OSCCs and identified that mutation in EGFR exon 19 and 21 may not contribute towards their genesis. The absence of mutations also indicates that oral cancerous lesions may not be as sensitive as other cancers to chemotherapeutic agents targeting EGFR.

Lewisy promotes migration of oral cancer cells by glycosylation of epidermal growth factor receptor

Aberrant glycosylation changes normal cellular functions and represents a specific hallmark of cancer. Lewis^y (Le^y) carbohydrate upregulation has been reported in a variety of cancers, including oral squamous cell carcinoma (OSCC). A high level of Le^y expression is related to poor prognosis of patients with oral cancer. However, it is unclear how Le^y mediates oral cancer progression. In this study, the role of Le^y in OSCC was explored. Our data showed that Le^y was upregulated in HSC-3 and OC-2 OSCC cell lines. Particularly, glycosylation of epidermal growth factor receptor (EGFR) with Le^y was found in OC-2 cells, and this modification was absent upon inhibition of Le^y synthesis. The absence of Le^y glycosylation of EGFR weakened phosphorylation of AKT and ERK in response to epidermal growth factor (EGF). Additionally, EGF-triggered cell migration was reduced, but cell proliferation was not affected. Le^y modification stabilized EGFR upon ligand activation. Conversely, absence of Le^y glycosylation accelerated EGFR degradation. In summary, these results indicate that increased expression of Le^y in OSCC cells is able to promote cell migration by modifying EGFR which in turn stabilizes EGFR expression and downstream signaling. Targeting Le^y on EGFR could have a potential therapeutic effect on oral cancer.

Tongue carcinoma infrequently harbor common actionable genetic alterations

BACKGROUND

Oral tongue squamous cell carcinomas (TSCC) are a unique subset of head and neck cancers with a distinct demographic profile, where up to half of the cases are never smokers. A small proportion of patients with OSCC are known to respond to EGFR TKI. We used a high-sensitivity mass spectrometry-based mutation profiling platform to determine the EGFR mutation status, as well as other actionable alterations in a series of Asian TSCC.

METHODS

66 TSCC patients treated between 1998-2009 with complete clinico-pathologic data were included in this study. Somatic mutation profiling was performed using Sequenom LungCarta v1.0, and correlated with clinical parameters.

RESULTS

Mutations were identified in 20/66(30.3%) of samples and involved TP53, STK11, MET, PIK3CA, BRAF and NRF2. No activating EGFR mutations or KRAS mutations were discovered in our series, where just over a third were never smokers. The most common mutations were in p53 (10.6%; n = 7) and MET (10.6%, n = 11) followed by STK11 (9.1%, n = 6) and PIK3CA (4.5%, n = 3). BRAF and NRF2 mutations, which are novel in TSCC, were demonstrated in one sample each. There was no significant correlation between overall mutation status and smoking history (p = 0.967) or age (p = 0.360). Positive MET alteration was associated with poorer loco-regional recurrence free survival (LRFS) of 11 months [vs 90 months in MET-negative group (p = 0.008)]. None of the other mutations were significantly correlated with LRFS or overall survival. Four of these tumors were propagated as immortalized cell lines and demonstrated the same mutations as the original tumor.

CONCLUSIONS

Using the Sequenom multiplexed LungCarta panel, we identified mutations in 6 genes, TP53, STK11, MET, PIK3CA, BRAF and NRF2, with the notable absence of EGFR and HER2 mutations in our series of Asian OSCC. Primary cell line models recapitulated the mutation profiles of the original primary tumours and provide an invaluable resource for experimental cancer therapeutics.

Areca nut components affect COX-2, cyclin B1/cdc25C and keratin expression, PGE2 production in keratinocyte is related to reactive oxygen species, CYP1A1, Src, EGFR and Ras signaling

AIMS

Chewing of betel quid (BQ) increases the risk of oral cancer and oral submucous fibrosis (OSF), possibly by BQ-induced toxicity and induction of inflammatory response in oral mucosa.

METHODS

Primary gingival keratinocytes (GK cells) were exposed to areca nut (AN) components with/without inhibitors. Cytotoxicity was measured by 3-(4,5-dimethyl- thiazol- 2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay. mRNA and protein expression was evaluated by reverse transcriptase-polymerase chain reaction (RT-PCR) and western blotting. PGE2/PGF2α production was measured by enzyme-linked immunosorbent assays.

RESULTS

Areca nut extract (ANE) stimulated PGE2/PGF2α production, and upregulated the expression of cyclooxygenase-2 (COX-2), cytochrome P450 1A1 (CYP1A1) and hemeoxygenase-1 (HO-1), but inhibited expression of keratin 5/14, cyclinB1 and cdc25C in GK cells. ANE also activated epidermal growth factor receptor (EGFR), Src and Ras signaling pathways. ANE-induced COX-2, keratin 5, keratin 14 and cdc25C expression as well as PGE2 production were differentially regulated by α-naphthoflavone (a CYP 1A1/1A2 inhibitor), PD153035 (EGFR inhibitor), pp2 (Src inhibitor), and manumycin A (a Ras inhibitor). ANE-induced PGE2 production was suppressed by piper betle leaf (PBL) extract and hydroxychavicol (two major BQ components), dicoumarol (a

NAD(P)H

Quinone Oxidoreductase--NQO1 inhibitor) and curcumin. ANE-induced cytotoxicity was inhibited by catalase and enhanced by dicoumarol, suggesting that AN components may contribute to the pathogenesis of OSF and oral cancer via induction of aberrant differentiation, cytotoxicity, COX-2 expression, and PGE2/PGF2α production.

CONCLUSIONS

CYP4501A1, reactive oxygen species (ROS), EGFR, Src and Ras signaling pathways could all play a role in ANE-induced pathogenesis of oral cancer. Addition of PBL into BQ and curcumin consumption could inhibit the ANE-induced inflammatory response.

Low PTEN expression is associated with worse overall survival in head and neck squamous cell carcinoma patients treated with chemotherapy and cetuximab

BACKGROUND

Platinum-based chemotherapy associated with cetuximab is the first-line treatment for inoperable recurrence or metastatic head and neck squamous cell carcinoma (HNSCC). There is no established biomarker for cetuximab efficacy in HNSCC. The PI3K pathway is one of the most frequently altered pathways in HNSCC. Loss of phosphatase and tensin homolog (PTEN) expression occurs in up to 30 % of cases.

METHODS

This was a retrospective analysis of data from 61 patients with inoperable recurrence or metastatic HNSCC treated with cetuximab. PTEN, epidermal growth factor receptor and p16 expression were analyzed by immunohistochemistry and tested for association with clinical outcomes.

RESULTS

Median overall survival was 11.4 months and progression-free survival was 6.9 months. Low PTEN expression was present in 26.2 % of patients and identified patients with worse prognosis. p16 was positive in only 8.5 % of tumors.

CONCLUSIONS

Low PTEN expression in patients treated with cetuximab plus chemotherapy emerged as a prognostic biomarker and should be evaluated for its predictive role for cetuximab efficacy.

Genome stability pathways in head and neck cancers

Genomic instability underlies the transformation of host cells toward malignancy, promotes development of invasion and metastasis and shapes the response of established cancer to treatment. In this review, we discuss recent advances in our understanding of genomic stability in squamous cell carcinoma of the head and neck (HNSCC), with an emphasis on DNA repair pathways. HNSCC is characterized by distinct profiles in genome stability between similarly staged cancers that are reflected in risk, treatment response and outcomes. Defective DNA repair generates chromosomal derangement that can cause subsequent alterations in gene expression, and is a hallmark of progression toward carcinoma. Variable functionality of an increasing spectrum of repair gene polymorphisms is associated with increased cancer risk, while aetiological factors such as human papillomavirus, tobacco and alcohol induce significantly different behaviour in induced malignancy, underpinned by differences in genomic stability. Targeted inhibition of signalling receptors has proven to be a clinically-validated therapy, and protein expression of other DNA repair and signalling molecules associated with cancer behaviour could potentially provide a more refined clinical model for prognosis and treatment prediction. Development and expansion of current genomic stability models is furthering our understanding of HNSCC pathophysiology and uncovering new, promising treatment strategies.

Anti-epidermal growth factor receptor therapy in head and neck squamous cell carcinoma: focus on potential molecular mechanisms of drug resistance

Targeted therapy against the epidermal growth factor receptor (EGFR) is one of the most promising molecular therapeutics for head and neck squamous cell carcinoma (HNSCC). EGFR is overexpressed in a wide range of malignancies, including HNSCC, and initiates important signal transduction pathways in HNSCC carcinogenesis. However, primary and acquired resistance are serious problems and are responsible for low single-agent response rate and tumor recurrence. Therefore, an improved understanding of the molecular mechanisms of resistance to EGFR inhibitors may provide valuable indications to identify biomarkers that can be used clinically to predict response to EGFR blockade and to establish new treatment options to overcome resistance. To date, no predictive biomarker for HNSCC is available in the clinic. Therapeutic resistance to anti-EGFR therapy may arise from mechanisms that can compensate for reduced EGFR signaling and/or mechanisms that can modulate EGFR-dependent signaling. In this review, we will summarize some of these molecular mechanisms and describe strategies to overcome that resistance.

Genetic deregulation of the PIK3CA oncogene in oral cancer

The phosphatidylinositol 3-kinase (PI3K)/Akt signaling pathway is one of the most commonly deregulated pathways in human cancers. PI3K comprises a catalytic (p110α) and regulatory subunit (p85), and p110α is encoded by the PIK3CA gene. Here, we summarize the known genetic alterations, including amplifications and mutations, of the PIK3CA oncogene in oral cancer. We discuss in detail PIK3CA mutations and their mutual exclusivity with pathway genes in addition to the incidence of PIK3CA mutations in relation to ethnicity. We describe the constitutive activation of PI3K signaling, oncogenicity, and the genetic deregulation of the PIK3CA gene and its association with oral cancer disease stage. We emphasize the importance of therapeutically targeting the genetically deregulated PIK3CA oncogene and its signaling. We also discuss the implications of targeting Akt and/or mTOR, which are the downstream effectors of PI3K that may possibly pave the way for molecular therapeutic targets for PIK3CA-driven oral carcinogenesis. Furthermore, this critical review provides a complete picture of the PIK3CA oncogene and its deregulation in oral cancer, which may facilitate early diagnosis and improve prognosis through personalized molecular targeted therapy in oral cancer.

Cyclin D1 overexpression and poor clinical outcomes in Taiwanese oral cavity squamous cell carcinoma

BACKGROUND

Cyclin D1 gene regulates cell cycle and plays an important role in the tumorigenesis of human cancers. The association between cyclin D1, clinicopathologic parameters and prognosis in oral cavity squamous cell carcinoma (OSCC) is inconclusive.

METHODS

A total of 264 male OSCCs were examined for cyclin D1 protein expression using immunohistochemistry (IHC). The expression levels of cyclin D1 were defined as overexpression when more than 10% of tumor cells displayed nuclear staining with moderate to strong intensity.

RESULTS

Overexpression of cyclin D1 was found in 97 (36.7%) OSCCs. Cyclin D1 protein overexpression was significantly associated with lymph node metastasis (P = 0.002), tumor cell differentiation (P = 0.031) and tumor stage (P = 0.051), but not associated with age onset, cigarette smoking, alcohol drinking, or areca quid chewing. Overexpression of cyclin D1 was also significantly associated with poor clinical outcomes in terms of disease-free survival (DFS, P = 0.002) and overall survival (OS, P < 0.001). The effects of cyclin D1 protein overexpression on DFS (hazard ratio (HR) = 1.540; 95% confidence interval (CI), 1.068 - 2.222) and OS (HR = 1.702; 95% CI, 1.168 - 2.480) were still existed after adjusting for clinicopathological parameters (such as age, primary tumor status, tumor cell differentiation, and lymph node metastasis) using logistic multivariate analysis.

CONCLUSION

Cyclin D1 protein worked as an independent prognostic factor and can be as a biomarker for the aggressiveness of OSCC.

Ras oncogenes in oral cancer: the past 20 years

Oral squamous cell carcinoma (OSCC) of head and neck is associated with high morbidity and mortality in both Western and Asian countries. Several risk factors for the development of oral cancer are very well established, including tobacco chewing, betel quid, smoking, alcohol drinking and human papilloma virus (HPV) infection. Apart from these risk factors, many genetic factors such as oncogenes, tumor suppressor genes and regulatory genes are identified to involve in oral carcinogenesis with these risk factors dependent and independent manner. Ras is one of the most frequently genetically deregulated oncogene in oral cancer. In this review, we analyze the past 22years of literature on genetic alterations such as mutations and amplifications of the isoforms of the ras oncogene in oral cancer. Further, we addressed the isoform-specific role of the ras in oral carcinogenesis. We also discussed how targeting the Akt and MEK, downstream effectors of the PI3K/Akt and MAPK pathways, respectively, would probably pave the possible molecular therapeutic target for the ras driven tumorigenesis in oral cancer. Analysis of these ras isoforms may critically enlighten specific role of a particular ras isoform in oral carcinogenesis, enhance prognosis and pave the way for isoform-specific molecular targeted therapy in OSCC.

Relationship between epidermal growth factor receptor gene copy number and protein expression in oral cavity squamous cell carcinoma

This study was designed to explore the relationship between epidermal growth factor receptor (EGFR) copy number and EGFR protein expression in oral cavity squamous cell carcinoma (OSCCs) in Taiwan. A total of 160 oral cavity squamous cell carcinomas were examined for EGFR protein overexpression using immunohistochemistry and for copy number using a fluorescence in situ hybridization (FISH) assay. Overexpression and increased gene copy numbers of EGFR were found in 75 (46.88%) and 50 (31.25%) cases, respectively. The concordance rate for EGFR gene amplification and protein overexpression was 100%. EGFR overexpression was associated with a poor prognosis both in terms of disease-free survival (DFS) and overall survival (OS). On the other hand, the association between an increase in EGFR gene copies and DFS or OS was insignificant. This was despite the observed significant associations between gene copy number and tumor stage, depth of tumor invasion, lymph node metastasis, bone invasion and perineural invasion. EGFR protein overexpression is closely related to EGFR copy number. Standard methodological and interpretation criteria need to be established that allows EGFR copy number combined with EGFR protein expression to be determined in a manner that allows individualized EGFR targeted therapy in OSCC patients.

Epidermal growth factor receptor gene copy number aberration at the primary tumour is significantly associated with extracapsular spread in oral cancer

Background:

Extracapsular spread (ECS) of lymph node metastasis in head and neck cancers, including oral squamous cell carcinomas (OSCCs), is known to reflect tumour aggressiveness, and is significantly associated with high rates of loco-regional recurrence, distant metastasis, and poor outcome. The purpose of this study was to confirm ECS as an important prognostic indicator and to determine the significant factors associated with ECS in OSCCs.

Methods:

We investigated the incidence of ECS and impact of ECS on survival in 127 OSCC patients. To determine the factors significantly correlated with ECS, we examined many factors, including the clinicopathological features of primary tumours, lymph node metastasis, and copy number aberrations of the cyclin D1 gene (CCND1) and epidermal growth factor receptor gene (EGFR) at primary tumours, and evaluated the value of predicting the risk of ECS of the metastatic lymph node.

Results:

Kaplan–Meier and multivariate disease-free and overall survival analysis clearly demonstrated that ECS is an independent prognostic factor in OSCCs. Moreover, logistic regression analysis showed that the number of pathologically positive nodes and copy number aberrations of EGFR at the primary tumour are independent predictors of ECS.

Conclusions:

The findings suggest that ECS is an independent prognostic factor in OSCCs. Moreover, the number of pathologically positive lymph nodes and EGFR numerical aberrations of the primary tumour were also shown to be excellent predictors of ECS in OSCCs. Preoperative evaluation of EGFR numerical aberrations might therefore be a useful tool for selecting patients at high risk of ECS, who would benefit from targeted aggressive multimodality therapy.

Epidermal growth factor receptor mutations in patients with oral cavity cancer in a betel nut chewing-prevalent area

BACKGROUND

Epidermal growth factor receptor (EGFR) mutations exist in patients with oral cavity squamous cell carcinoma (OSCC), but few data about mutation patterns with clinical outcomes were reported.

METHODS

Fifty-six formalin-fixed paraffin-embedded tumor samples were obtained surgically from OSCC patients. Direct sequencing of EGFR was carried out using nested polymerase chain reaction. The relationship between EGFR status and clinical courses was analyzed.

RESULTS

Two (3.56%) missense mutations (G857R; L862Q) in exon 20 were identified. Two types of silent mutation, A859A in exon 21 (1.79%) and Q787Q mutations in exon 20 (30.36%), were also found. No mutation was detected in exons 18 and 19. No significant difference in disease-free survival and locoregional control rate was shown between patients with and without Q787Q mutation.

CONCLUSIONS

We identified a high frequency of Q787Q mutation and a less prevalent active EGFR mutation in OSCC patients in Taiwan where betel nut is commonly chewed.

Clinical, pathological and molecular determinants in squamous cell carcinoma of the oral cavity

Squamous cell carcinoma of the oral cavity (OCSCC) is the most frequently observed form of head-and-neck cancer in Southeast Asia and is the sixth most common cancer worldwide. Most cases of this preventable disease are caused by alcohol consumption, smoking and betel nut chewing. The survival rates of patients with advanced OCSCC have not increased significantly in recent years. While treatments for OCSCC are similar worldwide, survival rates differ by geographical area. The various genetic profiles and individual genetic susceptibility for carcinogens may account for this discrepancy. In some respects, molecular alteration or accumulation affects tumor progression and the clinical outcomes among patients with OCSCC. Clarifying the tumor behavior of oral cancer, with regard to pathological features or molecular aspects, could help clinicians to judge, tailor and adopt more effective therapeutic strategies to treat oral cancer.