Global gene expression profile of nasopharyngeal carcinoma by laser capture microdissection and complementary DNA microarrays

Transcriptomic profiling revealed FZD10 as a novel biomarker for nasopharyngeal carcinoma recurrence

BACKGROUND

Nasopharyngeal carcinoma (NPC) is a type of cancers that develops in the nasopharynx, the very upper part of the throat behind the nose. NPC is typically diagnosed in later stages of the disease and has a high rate of recurrence due to the location of the tumor growth site. In this study, we compared the gene expression profiles of NPC tissues from patients with and without recurrence to identify potential molecular biomarkers of NPC recurrence.

METHODS

Microarrays were used to analyze the expression of genes in 15 NPC tissues taken at the time of diagnosis and at the site of recurrence following therapeutic treatment. Pathway enrichment analysis was used to examine the biological interactions between the major differentially expressed genes. The target identified was then validated using immunohistochemistry on 86 NPC tissue samples.

RESULTS

Our data showed that the Wnt signaling pathway was enhanced in NPC tissues with recurrence. FZD10, a component of the Wnt signaling pathway, was significantly expressed in NPC tissues, and was significantly associated with NPC recurrence.

CONCLUSION

Our study provides new insights into the pathogenesis of NPC and identifies FZD10 as a potential molecular biomarker for NPC recurrence. FZD10 may be a promising candidate for NPC recurrence and a potential therapeutic target.

Applicability of spatial transcriptional profiling to cancer research

Spatial transcriptional profiling provides gene expression information within the important anatomical context of tissue architecture. This approach is well suited to characterizing solid tumors, which develop within a complex landscape of malignant cells, immune cells, and stroma. In a single assay, spatial transcriptional profiling can interrogate the role of spatial relationships among these cell populations as well as reveal spatial patterns of relevant oncogenic genetic events. The broad utility of this approach is reflected in the array of strategies that have been developed for its implementation as well as in the recent commercial development of several profiling platforms. The flexibility to apply these technologies to both hypothesis-driven and discovery-driven studies allows widespread applicability in research settings. This review discusses available technologies for spatial transcriptional profiling and several applications for their use in cancer research.

Targeting Non-Oncogene Addiction for Cancer Therapy

While Next-Generation Sequencing (NGS) and technological advances have been useful in identifying genetic profiles of tumorigenesis, novel target proteins and various clinical biomarkers, cancer continues to be a major global health threat. DNA replication, DNA damage response (DDR) and repair, and cell cycle regulation continue to be essential systems in targeted cancer therapies. Although many genes involved in DDR are known to be tumor suppressor genes, cancer cells are often dependent and addicted to these genes, making them excellent therapeutic targets. In this review, genes implicated in DNA replication, DDR, DNA repair, cell cycle regulation are discussed with reference to peptide or small molecule inhibitors which may prove therapeutic in cancer patients. Additionally, the potential of utilizing novel synthetic lethal genes in these pathways is examined, providing possible new targets for future therapeutics. Specifically, we evaluate the potential of TONSL as a novel gene for targeted therapy. Although it is a scaffold protein with no known enzymatic activity, the strategy used for developing PCNA inhibitors can also be utilized to target TONSL. This review summarizes current knowledge on non-oncogene addiction, and the utilization of synthetic lethality for developing novel inhibitors targeting non-oncogenic addiction for cancer therapy.

Clinical Significance of Integrin Subunit Beta 4 in Head and Neck Squamous Cell Carcinoma

Background: The expression level and clinical significance of integrin subunit beta 4 (ITGB4) in head and neck squamous cell carcinoma (HNSCC) remain unclear. Materials and Methods: Expression of ITGB4 in HNSCC tissues were evaluated by calculating standard mean differences (SMDs) based on gene chips, RNA-seq, and immunohistochemistry data (n = 2330) from multiple sources. Receiver operating characteristic (ROC) curves were used to detect the ability of ITGB4 to distinguish HNSCC from non-HNSCC samples. The relationship between the expression level of ITGB4 and clinical parameters was evaluated by calculating SMDs. Results: Identical results of mRNA and protein levels indicated remarkable up-expression of ITGB4 in HNSCC tissues. Further ROC curves showed that ITGB4 could distinguish HNSCC from non-HNSCC samples. Genetic alteration analysis of ITGB4 in HNSCC indicated that overexpression of ITGB4 in HNSCC was likely not owing to genetic alteration of ITGB4. Moreover, ITGB4 overexpression level may be correlated with clinical T stage. Conclusion: ITGB4 likely plays an essential role in HNSCC occurrence based on our study and its potential diagnostic value is worthy of further exploration in the future.

Cotargeting CHK1 and PI3K Synergistically Suppresses Tumor Growth of Oral Cavity Squamous Cell Carcinoma in Patient-Derived Xenografts

Oral cavity squamous cell carcinomas (OSCCs) are aggressive tumors, and their recurrence leads to poor prognosis and reduced survival rates. This study aimed to identify therapeutic targets and to evaluate the efficacy of targeted inhibitors in OSCC patient-derived xenograft (PDX) models. Herein, we reported that OSCC PDXs recapitulated the genomic signatures of their paired primary tumors and the expression of CHEK1, PIK3CA, and PIK3CD was significantly upregulated in OSCC. The antitumor efficacy of CHK1 inhibitors (PF477736, AZD7762, LY2606368) and PI3K inhibitors (BYL719, GDC0941, GSK1059615) was investigated in OSCC cell lines and PDX models. Targeting either CHK1 or PI3K effectively inhibited cell proliferation and colony formation by inducing cell cycle arrest and apoptosis in in vitro cell-based assays. Cisplatin-based chemotherapy combined with CHK1 inhibitor treatment synergistically inhibited cell proliferation by suppressing CHK1 phosphorylation and inducing PARP cleavage. Furthermore, compared with monotherapy, cotreatment with CHK1 and PI3K inhibitors exerted synergistic anticancer effects by suppressing CHK1, AKT, and 4E-BP1 phosphorylation. In summary, our study identified CHK1 and PI3K as promising targets, especially in a dual treatment strategy combining a CHK1 inhibitor with cisplatin or a PI3K inhibitor as a novel therapeutic approach for OSCC patients with aberrant cell cycle regulation and PI3K signaling activation.

Screening of urine identifies PLA2G16 as a field defect methylation biomarker for prostate cancer detection

BACKGROUND

Prostate cancer (PC) is a multifocal disease. DNA methylation alterations are not restricted to the immediate peritumor environment, but spatially widespread in the adjacent and distant histologically normal prostate tissues. In the current study, we utilized high-throughput methylation arrays to identify epigenetic changes in the urine from men with and without cancer.

DESIGN, SETTING, AND PARTICIPANTS

DNA urine samples were enriched for methylated fragments using MBD methyl-binding antibodies and applied to high density CytoScanHD arrays. Significant loci were validated using quantitative pyrosequencing and binary logistic regression modeling applied to urine sample analyses in a training (n = 83) and validation approach (n = 84). Methylation alterations in prostate tissues using pyrosequencing at the PLA2G16 locus were examined in 38 histologically normal specimens from men with (TA, n = 26) and without (NTA, n = 12) cancer and correlated to gene expression.

RESULTS

Methylation microarrays identified 3,986 loci showing significantly altered methylation in the urine samples from patients with PC compared to those without (TA vs NTA; p<0.01). These loci were then compared against subjects with their prostates removed to exclude non-prostate cell markers yielding 196 significant regions. Multiple CpGs adjacent to PLA2G16 CpG island showed increased methylation in TA compared to NTA (p<0.01) in a large validation study of urine samples. The predictive accuracy of PLA2G16 methylation at CG2 showed the highest predictive value at 0.8 (odds ratio, 1.37; 95% confidence interval, 1.16-1.62; p<0.001). Using a probability cutoff of 0.065, the sensitivity and specificity of the multivariate model was 92% and 35%. When histologically normal prostate tissues/biopsies from patients with PC (TA) were compared to subjects without cancer, significant hypermethylation of PLA2G16 was noted (odds ratio, 1.35; 95% confidence interval, 1.07-1.71; p = 0.01).

CONCLUSION

PLA2G16 methylation defines an extensive field defect in histologically normal prostate tissue associated with PC. PLA2G16 methylation in urine and prostate tissues can detect the presence of PC.

Checkpoint Kinase 1 Expression Predicts Poor Prognosis in Nigerian Breast Cancer Patients

BACKGROUND

Checkpoint kinase 1 (CHEK1), a DNA damage sensor and cell death pathway stimulator, is regarded as an oncogene in tumours, where its activities are considered essential for tumourigenesis and the survival of cancer cells treated with chemotherapy and radiotherapy. In breast cancer, CHEK1 expression has been associated with an aggressive tumour phenotype, the triple-negative breast cancer subtype, an aberrant response to tamoxifen, and poor prognosis. However, the relevance of CHEK1 expression has, hitherto, not been investigated in an indigenous African population. We therefore aimed to investigate the clinicopathological, biological, and prognostic significance of CHEK1 expression in a cohort of Nigerian breast cancer cases.

MATERIAL AND METHODS

Tissue microarrays of 207 Nigerian breast cancer cases were tested for CHEK1 expression using immunohistochemistry. The clinicopathological, molecular, and prognostic characteristics of CHEK1-positive tumours were determined using the Chi-squared test and Kaplan-Meier and Cox regression analyses in SPSS Version 16.

RESULTS

Nuclear expression of CHEK1 was present in 61% of breast tumours and was associated with tumour size, triple-negative cancer, basal-like phenotype, the epithelial-mesenchymal transition, p53 over-expression, DNA homologous repair pathway dysfunction, and poor prognosis.

CONCLUSIONS

The rate expression of CHEK1 is high in Nigerian breast cancer cases and is associated with an aggressive phenotype and poor prognosis.

Epstein-Barr virus stably confers an invasive phenotype to epithelial cells through reprogramming of the WNT pathway

Epstein-Barr virus (EBV)-associated carcinomas, such as nasopharyngeal carcinoma (NPC), exhibit an undifferentiated and metastatic phenotype. To determine viral contributions involved in the invasive phenotype of EBV-associated carcinomas, EBV-infected human telomerase-immortalized normal oral keratinocytes (NOK) were investigated. EBV-infected NOK were previously shown to undergo epigenetic reprogramming involving CpG island hypermethylation and delayed responsiveness to differentiation. Here, we show that EBV-infected NOK acquired an invasive phenotype that was epigenetically retained after viral loss. The transcription factor lymphoid enhancer factor 1 (LEF1) and the secreted ligand WNT5A, expressed in NPC, were increased in EBV-infected NOK with sustained expression for more than 20 passages after viral loss. Increased LEF1 levels involved four LEF1 variants, and EBV-infected NOK showed a lack of responsiveness to β-catenin activation. Although forced expression of WNT5A and LEF1 enhanced the invasiveness of parental NOK, LEF1 knockdown reversed the invasive phenotype of EBV-infected NOK in the presence of WNT5A. Viral reprogramming of LEF1 and WNT5A was observed several passages after EBV infection, suggesting that LEF1 and WNT5A may provide a selective advantage to virally-infected cells. Our findings suggest that EBV epigenetically reprogrammed epithelial cells with features of basal, wound healing keratinocytes, with LEF1 contributing to the metastatic phenotype of EBV-associated carcinomas.

Ataxin-3 promotes genome integrity by stabilizing Chk1

The Chk1 protein is essential for genome integrity maintenance and cell survival in eukaryotic cells. After prolonged replication stress, Chk1 can be targeted for proteasomal degradation to terminate checkpoint signaling after DNA repair finishes. To ensure proper activation of DNA damage checkpoint and DNA repair signaling, a steady-state level of Chk1 needs to be retained under physiological conditions. Here, we report a dynamic signaling pathway that tightly regulates Chk1 stability. Under unperturbed conditions and upon DNA damage, ataxin-3 (ATX3) interacts with Chk1 and protects it from DDB1/CUL4A- and FBXO6/CUL1-mediated polyubiquitination and subsequent degradation, thereby promoting DNA repair and checkpoint signaling. Under prolonged replication stress, ATX3 dissociates from Chk1, concomitant with a stronger binding between Chk1 and its E3 ligase, which causes Chk1 proteasomal degradation. ATX3 deficiency results in pronounced reduction of Chk1 abundance, compromised DNA damage response, G2/M checkpoint defect and decreased cell survival after replication stress, which can all be rescued by ectopic expression of ATX3. Taken together, these findings reveal ATX3 to be a novel deubiquitinase of Chk1, providing a new mechanism of Chk1 stabilization in genome integrity maintenance.

Epstein-Barr virus-encoded LMP2A stimulates migration of nasopharyngeal carcinoma cells via the EGFR/Ca2+/calpain/ITGβ4 axis

Epstein-Barr virus (EBV)-encoded latent membrane protein 2A (LMP2A) promotes the motility of nasopharyngeal carcinoma (NPC) cells. Previously, we have shown that the localization of integrin β4 (ITGβ4) is regulated by LMP2A, with ITGβ4 concentrated at the cellular protrusions in LMP2A-expressing NPC cells. In the present study, we aim to further investigate mechanisms involved in this process and its contribution to cell motility. We show that expression of LMP2A was correlated with increased epidermal growth factor receptor (EGFR) activation, elevated levels of intracellular Ca²⁺, calpain activation and accelerated cleavage of ITGβ4. Activation of EGFR and calpain activity was responsible for a redistribution of ITGβ4 from the basal layer of NPC cells to peripheral membrane structures, which correlated with an increased migratory capacity of NPC cells. Furthermore, we demonstrated that the calpain inhibitor calpastatin was downregulated in NPC primary tumors. In conclusion, our results point to LMP2A-mediated targeting of the EGFR/Ca²⁺/calpain/ITGβ4 signaling system as a mechanism underlying the increased motility of NPC cells. We suggest that calpain-facilitated cleavage of ITGβ4 contributes to the malignant phenotype of NPC cells.

Summary: LMP2A expression in nasopharyngeal carcinoma cells increases EGFR activation and cytosolic Ca²⁺, subsequently stimulates calpain-dependent cleavage of ITGβ4 and enhances cell motility.

Application of a patient-derived xenograft model in cytolytic viral activation therapy for nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is an Epstein Barr virus (EBV)-related malignancy in which the tumor microenvironment plays a pivotal role in tumor progression. Here, we developed two patient-derived xenograft (PDX) mouse lines from engrafted NPC metastatic tumors. Positive staining for EBV-encoded small RNAs confirmed that these tumors harbored EBV, and gene expression profile analyses further showed that the PDX was highly similar to the primary parent tumor. In vivo drug screening using the PDX system demonstrated that gemcitabine had the best antitumor effect among the tested drugs. The donor of this PDX also showed excellent responsiveness to gemcitabine treatment. The combination of gemcitabine and valproic acid exerted synergistic antitumor effects. Further addition of ganciclovir to this two-drug combination regimen enhanced cytolytic viral activation, yielding the best antitumor response among tested regimens. Treatment with this three-drug combination regimen decreased plasma EBV-DNA load, tumor viral concentration, and the number of viable tumor cells to a greater extent than the two-drug gemcitabine and valproic acid combination. These results highlight the value of PDX models in the development of EBV-targeted strategies to treat NPC.

Conformational Change of Human Checkpoint Kinase 1 (Chk1) Induced by DNA Damage

Phosphorylation of Chk1 by ataxia telangiectasia-mutated and Rad3-related (ATR) is critical for checkpoint activation upon DNA damage. However, how phosphorylation activates Chk1 remains unclear. Many studies suggest a conformational change model of Chk1 activation in which phosphorylation shifts Chk1 from a closed inactive conformation to an open active conformation during the DNA damage response. However, no structural study has been reported to support this Chk1 activation model. Here we used FRET and bimolecular fluorescence complementary techniques to show that Chk1 indeed maintains a closed conformation in the absence of DNA damage through an intramolecular interaction between a region (residues 31-87) at the N-terminal kinase domain and the distal C terminus. A highly conserved Leu-449 at the C terminus is important for this intramolecular interaction. We further showed that abolishing the intramolecular interaction by a Leu-449 to Arg mutation or inducing ATR-dependent Chk1 phosphorylation by DNA damage disrupts the closed conformation, leading to an open and activated conformation of Chk1. These data provide significant insight into the mechanisms of Chk1 activation during the DNA damage response.

CHK1 and replicative stress in T-cell leukemia: Can an irreverent tumor suppressor end up playing the oncogene?

Replicative stress (RS) is a cell-intrinsic phenomenon enhanced by oncogenic transformation. Checkpoint kinase 1 (CHK1) is a key component of the ATR-dependent DNA damage response pathway that protects cells from RS by preventing replication fork collapse and activating homologous DNA repair. Taking this knowledge into account, one would predict CHK1 behaves strictly as a tumor suppressor. However, the reality seems far more complex. CHEK1 loss-of-function mutations have not been found in human tumors, and transgenic expression of Chek1 in mice promotes oncogene-induced transformation through RS inhibition. Moreover, CHK1 is overexpressed in various human cancers and CHK1 inhibitors have been developed as sensitizers to enhance the cytotoxicity of DNA damage-inducing chemotherapies. Here, we summarize the literature on the involvement of CHK1 in cancer progression, including our recent observation that CHK1 sustains T-cell acute lymphoblastic leukemia (T-ALL) cell viability. We also debate the importance of identifying patients that could benefit the most from treatment with CHK1 inhibitors, taking T-ALL as a model, and propose possible markers of therapeutic response.

Trial Watch: Targeting ATM-CHK2 and ATR-CHK1 pathways for anticancer therapy

The ataxia telangiectasia mutated serine/threonine kinase (ATM)/checkpoint kinase 2 (CHEK2, best known as CHK2) and the ATM and Rad3-related serine/threonine kinase (ATR)/CHEK1 (best known as CHK1) cascades are the 2 major signaling pathways driving the DNA damage response (DDR), a network of processes crucial for the preservation of genomic stability that act as a barrier against tumorigenesis and tumor progression. Mutations and/or deletions of ATM and/or CHK2 are frequently found in tumors and predispose to cancer development. In contrast, the ATR-CHK1 pathway is often upregulated in neoplasms and is believed to promote tumor growth, although some evidence indicates that ATR and CHK1 may also behave as haploinsufficient oncosuppressors, at least in a specific genetic background. Inactivation of the ATM-CHK2 and ATR-CHK1 pathways efficiently sensitizes malignant cells to radiotherapy and chemotherapy. Moreover, ATR and CHK1 inhibitors selectively kill tumor cells that present high levels of replication stress, have a deficiency in p53 (or other DDR players), or upregulate the ATR-CHK1 module. Despite promising preclinical results, the clinical activity of ATM, ATR, CHK1, and CHK2 inhibitors, alone or in combination with other therapeutics, has not yet been fully demonstrated. In this Trial Watch, we give an overview of the roles of the ATM-CHK2 and ATR-CHK1 pathways in cancer initiation and progression, and summarize the results of clinical studies aimed at assessing the safety and therapeutic profile of regimens based on inhibitors of ATR and CHK1, the only 2 classes of compounds that have so far entered clinics.

Omics-based identification of biomarkers for nasopharyngeal carcinoma

Nasopharyngeal carcinoma (NPC) is a head and neck cancer that is highly found in distinct geographic areas, such as Southeast Asia. The management of NPC remains burdensome as the prognosis is poor due to the late presentation of the disease and the complex nature of NPC pathogenesis. Therefore, it is necessary to find effective molecular markers for early detection and therapeutic measure of NPC. In this paper, the discovery of molecular biomarker for NPC through the emerging omics technologies including genomics, miRNA-omics, transcriptomics, proteomics, and metabolomics will be extensively reviewed. These markers have been shown to play roles in various cellular pathways in NPC progression. The knowledge on their function will help us understand in more detail the complexity in tumor biology, leading to the better strategies for early detection, outcome prediction, detection of disease recurrence, and therapeutic approach.

Correlation of CCNA1 promoter methylation with malignant tumors: a meta-analysis introduction

Epigenetic silencing of tumor suppressor genes by promoter methylation plays vital roles in the process of carcinogenesis. The purpose of this meta-analysis was to determine whether the aberrant methylation of cyclin A1 (CCNA1) may be of great significance to human malignant tumors. By searching both English and Chinese language-based electronic databases carefully, we tabulated and analyzed parameters from each study. All human-associated case-control studies were included providing available data for CCNA1 methylation and reporting the adjusted odds ratios (ORs) and 95% confidence intervals (CI) conducted with the use of Version 12.0 STATA software. A total of 10 case-control studies (619 patients with cancers and 292 healthy controls) were included for the following statistical analysis. Pooled OR values from all articles revealed that the frequency of CCNA1 methylation in cancer tissues was significantly higher than those of normal tissues (P < 0.001). Further ethnicity indicated that the frequency of CCNA1 methylation was correlated with the development of malignant tumors among all those included experimental subgroups (all P < 0.05). These data from results indicated a significant connection of CCNA1 methylation with poor progression in human malignant tumors among both Caucasian and Asian populations.

Rules of parotid gland dose variations and shift during intensity modulated radiation therapy for nasopharyngeal carcinoma

Background

To determine the position and dose delivery changes rules of parotid gland (PG) during the course of intensity modulated radiation therapy (IMRT) in nasopharyngeal carcinoma patients (NPC).

Materials and methods

One hundred and forty one competed tomography (CT) images from 47 NPC patients (three images for each patient were acquired before treatment, at the 15th and 25th fraction during the treatment) who underwent radical IMRT were selected for this study. A total of 70-76Gy at 2.12–2.3 Gy/fraction/d was given to the GTVnx in 33 fractions. The distances between the lateral/medial aspects of PG and midline (DLM and DMM) at the level of odontoid process were measured. The dose differences between plan and actual delivery were calculated.

Results

The volume reductions of PGs between fractions 15 and 25 were larger than those in the first 15 fractions (4.68 ± 3.23 cc vs. 2.46 ± 4.55 cc for the right PG and 5.96 ± 2.99 cc vs. 2.06 ± 2.99 cc for the left PG). However, the percentage of gland volume receiving ≥30 Gy (V30) of bilateral PGs decreased more significantly in the first 15 fractions than that between fractions 15 and 25 (5.61 ± 16.04% vs. 1.14 ± 21.54% for the right PG and 6.87 ± 15.58% vs. 0.81 ± 15.94% for the left PG). The gross tumor volume of the nasopharynx (GTVnx) decreased more significantly in the first 15 fractions than that between the 15th and 25th fraction (8.23 ± 13.61 cc vs. 3.30 ± 8.09 cc). The DMM of ipsilateral PGs reduced in the first 15 fractions (0.80 ± 2.96 mm) but increased between fraction 15 and 25 (−2.19 ± 3.96 mm). While ipsilateral PG shifted into target volume but shifted out target volume between fraction 15 and 25. Parotid glands V30 was correlated with GTVnx, GTVnx reduction and DMM reduction (p < 0.01).

Conclusion

Our results indicate that the reduction of GTVnx leads to the positional change of the parotid gland, which results in more significant dose change of the parotid gland in the first 15 fractions than that between fraction 15 and 25.

Lactotransferrin could be a novel independent molecular prognosticator of nasopharyngeal carcinoma

Lactotransferrin (LTF), also known as lactoferrin, is a key component of innate immune defense. We previously reported that LTF was downregulated in nasopharyngeal carcinoma (NPC) and could suppress NPC cell proliferation. However, the relevance of the relationship between LTF expression and NPC clinical outcome has not been reported. This study aims to assess the possible correlations between LTF expression and clinical parameters and its potential prognostic predictive ability in the outcomes of patients with NPC. Complementary DNA (cDNA) microarray, quantitative real-time PCR (qRT-PCR), and immunohistochemistry (IHC) results suggested that LTF expression was significantly downregulated in NPC tissues compared to non-NPC tissues. LTF was negatively correlated with lymph node metastasis (P = 0.042), T stage (P < 0.001), clinical tumor-node-metastasis (TNM) stage (P = 0.022), and EBV-encoded RNA 1 (EBER-1) expression (r = -.167, P = 0.016). A survival analysis of 108 patients with NPC revealed that positive expression of LTF could predict a good prognosis [disease-free survival (DFS): P = 0.043, overall survival (OS): P = 0.040]. Multivariable analysis revealed that LTF could independently predict prognosis (DFS: HR = 0.414, P = 0.003; OS: HR = 0.309, P = 0.005). These observations indicated that LTF is a potential prognostic factor of NPC.

5‑FU resistance abrogates the amplified cytotoxic effects induced by inhibiting checkpoint kinase 1 in p53‑mutated colon cancer cells

The emergence of chemoresistance is a major limitation of current cancer therapies, and checkpoint kinase (Chk1) 1 positively correlates with resistance to chemo‑ or radio‑therapy. Cancer cells lacking p53 pathways are completely dependent on the S and G2/M checkpoints via Chk1; therefore, Chk1 inhibition enhances the cytotoxicity of DNA‑damaging agents only in p53‑deficient cells. However, little is known about the synergistic effect of Chk1 inhibition with 5‑FU, the most frequently used antimetabolite, in chemoresistant colorectal cells. In this study, we found that 5‑FU induced S‑phase arrest only in p53‑deficient colorectal cancer cells. 5‑FU treatment induced DNA damage and activation of ataxia telangiectasia mutated (ATM) and Chk1, leading to S‑phase arrest, and Chk1 inhibition using SB218078 reduced S‑phase arrest and increased apoptosis in the presence of 5‑FU. In contrast, in p53‑deficient, 5‑FU‑resistant (5FUR) colon cancer cells that we developed, 5‑FU enhanced DNA damage but did not induce Chk1/ATM activation or cell cycle arrest. SB218078 in combination with 5‑FU did not induce apoptosis. These results indicate that 5‑FU‑resistance abrogated the anticancer effect amplified by Chk1 inhibition, even in p53‑deficient cancer cells.

Oncogenic effects of WNT5A in Epstein-Barr virus‑associated nasopharyngeal carcinoma

The molecular events that drive the progression of Epstein-Barr virus (EBV)-associated nasopharyngeal carcinoma (NPC) are still to be elucidated. Here, we report for the first time the pathogenic significance of an NPC-associated gene, wingless-type MMTV integration site family, member 5A (WNT5A) and the contribution of EBV to its expression. WNT5A is a representative Wnt protein that activates non-canonical Wnt signalling. With regard to its role in carcinogenesis, there is conflicting evidence as to whether WNT5A has a tumour-promoting or tumour-suppressive role. We show that WNT5A is upregulated in primary NPC tissue samples. We also demonstrate that WNT5A expression was dramatically increased in NPC cell lines expressing the EBV-encoded LMP2A gene, suggesting that this EBV-encoded latent gene is responsible for upregulating WNT5A in NPC. In addition, in vitro WNT5A overexpression promotes the proliferation, migration and invasion of NPC cells. Our results not only reveal pro-tumorigenic effects of WNT5A in NPC but also suggest that WNT5A could be an important therapeutic target in patients with EBV-associated disease.

Roles of Chk1 in cell biology and cancer therapy

The evolutionally conserved DNA damage response (DDR) and cell cycle checkpoints preserve genome integrity. Central to these genome surveillance pathways is a protein kinase, Chk1. DNA damage induces activation of Chk1, which then transduces the checkpoint signal and facilitates cell cycle arrest and DNA damage repair. Significant progress has been made recently toward our understanding of Chk1 regulation and its implications in cancer etiology and therapy. Specifically, a model that involves both spatiotemporal and conformational changes of proteins has been proposed for Chk1 activation. Further, emerging evidence suggests that Chk1 does not appear to be a tumor suppressor; instead, it promotes tumor growth and may contribute to anticancer therapy resistance. Recent data from our laboratory suggest that activating, but not inhibiting, Chk1 in the absence of chemotherapy might represent an innovative approach to suppress tumor growth. These findings suggest unique regulation of Chk1 in cell biology and cancer etiology, pointing to novel strategies for targeting Chk1 in cancer therapy.

Anti-tumor effect of SLPI on mammary but not colon tumor growth

Secretory leukocyte protease inhibitor (SLPI) is a serine protease inhibitor that was related to cancer development and metastasis dissemination on several types of tumors. However, it is not known the effect of SLPI on mammary and colon tumors. The aim of this study was to examine the effect of SLPI on mammary and colon tumor growth. The effect of SLPI was tested on in vitro cell apoptosis and in vivo tumor growth experiments. SLPI over-expressing human and murine mammary and colon tumor cells were generated by gene transfection. The administration of murine mammary tumor cells over-expressing high levels of SLPI did not develop tumors in mice. On the contrary, the administration of murine colon tumor cells over-expressing SLPI, developed faster tumors than control cells. Intratumoral, but not intraperitoneal administration of SLPI, delayed the growth of tumors and increased the survival of mammary but not colon tumor bearing mice. In vitro culture of mammary tumor cell lines treated with SLPI, and SLPI producer clones were more prone to apoptosis than control cells, mainly under serum deprivation culture conditions. Herein we demonstrated that SLPI induces the apoptosis of mammary tumor cells in vitro and decreases the mammary but not colon tumor growth in vivo. Therefore, SLPI may be a new potential therapeutic tool for certain tumors, such as mammary tumors.

A global view of the oncogenic landscape in nasopharyngeal carcinoma: an integrated analysis at the genetic and expression levels

Previous studies have reported that the tumour cells of nasopharyngeal carcinoma (NPC) exhibit recurrent chromosome abnormalities. These genetic changes are broadly assumed to lead to changes in gene expression which are important for the pathogenesis of this tumour. However, this assumption has yet to be formally tested at a global level. Therefore a genome wide analysis of chromosome copy number and gene expression was performed in tumour cells micro-dissected from the same NPC biopsies. Cellular tumour suppressor and tumour-promoting genes (TSG, TPG) and Epstein-Barr Virus (EBV)-encoded oncogenes were examined. The EBV-encoded genome maintenance protein EBNA1, along with the putative oncogenes LMP1, LMP2 and BARF1 were expressed in the majority of NPCs that were analysed. Significant downregulation of expression in an average of 76 cellular TSGs per tumour was found, whilst a per-tumour average of 88 significantly upregulated, TPGs occurred. The expression of around 60% of putative TPGs and TSGs was both up-and down-regulated in different types of cancer, suggesting that the simplistic classification of genes as TSGs or TPGs may not be entirely appropriate and that the concept of context-dependent onco-suppressors may be more extensive than previously recognised. No significant enrichment of TPGs within regions of frequent genomic gain was seen but TSGs were significantly enriched within regions of frequent genomic loss. It is suggested that loss of the FHIT gene may be a driver of NPC tumourigenesis. Notwithstanding the association of TSGs with regions of genomic loss, on a gene by gene basis and excepting homozygous deletions and high-level amplification, there is very little correlation between chromosomal copy number aberrations and expression levels of TSGs and TPGs in NPC.

Calpain 2 regulates Akt-FoxO-p27(Kip1) protein signaling pathway in mammary carcinoma

We investigated the role of the ubiquitously expressed calpain 2 isoform in breast tumor cell growth, migration, signaling, and tumorigenesis. RNAi-mediated knockdown of the capn2 transcript was used to manipulate expression of the catalytic subunit of calpain 2 in the AC2M2 mouse mammary carcinoma cell line. Stable knockdown of capn2 correlated with reduced in vitro proliferation rates, soft agar colony formation efficiency, and migration rates, indicating roles for calpain 2 in mitogenesis, survival, and motogenesis. Biochemical analysis showed increased levels of protein phosphatase 2A and reduced levels of activated Akt in calpain 2-deficient cells, and this correlated with increased levels of the FoxO3a target gene product p27(Kip1), a key regulator of cell proliferation. Calpain 2 deficiency in the AC2M2 cells correlated with enhanced nuclear localization of FoxO3a, consistent with it being in a derepressed state capable of regulating transcriptional targets. Orthotopically engrafted calpain 2 knockdown AC2M2 cells generated tumors with reduced growth rates and enhanced in vivo expression of p27(Kip1). In summary, calpain 2 deficiency correlated with reduced Akt activity, increased protein phosphatase 2A levels, derepression of FoxO3a, and enhanced expression of the p27(Kip1) tumor suppressor. These observations argue that calpain 2 promotes tumor cell growth both in vitro and in vivo through the PI3K-Akt-FoxO-p27(Kip1) signaling cascade. Inhibition of calpain 2 might therefore provide therapeutic benefits in the treatment of cancer.

Nasopharyngeal carcinoma signaling pathway: an update on molecular biomarkers

Nasopharyngeal carcinoma (NPC) is an uncommon cancer, which has a distinctive ethnic and geographic distribution. Etiology of NPC is considered to be related with a complex interaction of environmental and genetic factors as well as Epstein-Barr virus infection. Since NPC is located in the silent painless area, the disease is usually therefore diagnosed at the advanced stages; hence early detection of NPC is difficult. Furthermore, understanding in molecular pathogenesis is still lacking, pondering the identification of effective prognostic and diagnostic biomarkers. Dysregulation of signaling molecules in intracellular signal transduction, which regulate cell proliferation, apoptosis, and adhesion, underlines the basis of NPC pathogenesis. In this paper, the molecular signaling pathways in the NPC are discussed for the holistic view of NPC development and progression. The important insights toward NPC pathogenesis may offer strategies for identification of novel biomarkers for diagnosis and prognosis.

MHC class I molecules act as tumor suppressor genes regulating the cell cycle gene expression, invasion and intrinsic tumorigenicity of melanoma cells

The alteration of MHC class I (MHC-I) expression is a frequent event during cancer progression, allowing tumor cells to evade the immune system. We report that the loss of one major histocompatibility complex haplotype in human melanoma cells not only allowed them to evade immunosurveillance but also increased their intrinsic oncogenic potential. A second successive defect in MHC-I expression, MHC-I total downregulation, gave rise to melanoma cells that were more oncogenic per se in vivo and showed a higher proliferation rate and greater migratory and invasive potential in vitro. All these processes were reversed by restoring MHC-I expression via human leukocite antigen-A2 gene transfection. MHC-I cell surface expression was inversely correlated with intrinsic oncogenic potential. Modifications in the expression of various cell cycle genes were correlated with changes in MHC-I expression; the most important differences among the melanoma cell lines were in the transcriptional level of AP2-alpha, cyclin A1 and p21WAF1/CIP1. According to these results, altered MHC-I expression in malignant cells can directly increase their intrinsic oncogenic and invasive potential and modulate the expression of cell cycle genes. These findings suggest that human leukocite antigen class I molecules may act directly as tumor suppressor genes in melanoma.

Integrated analysis of multiple gene expression profiling datasets revealed novel gene signatures and molecular markers in nasopharyngeal carcinoma

PURPOSE

To identify the novel gene signatures and molecular markers of nasopharyngeal carcinoma (NPC) by integrated bioinformatics analysis of multiple gene expression profiling datasets.

EXPERIMENTAL DESIGN

Seven published gene expression profiling studies and one of our unpublished works were reanalyzed to identify the common significantly dysregulated (CSD) genes in NPC. Overrepresentation analysis of cytogenetic bands, Gene Ontology (GO) categories, pathways were used to explore CSD genes functionally associated with carcinogenesis. The protein expressions of selected CSD genes were examined by immunohistochemistry on tissue microarrays, and the correlations of their expressions with clinical outcomes were evaluated.

RESULTS

Using the criteria (genes reported deregulated in more than one study), a total of 962 genes were identified as the CSD genes in NPC. Four upregulated (BUB1B, CCND2, CENPF, and MAD2L1) and two downregulated (LTF and SLPI) genes were markedly reported in six studies. The enrichments of chromosome aberrations were 2q23, 2q31, 7p15, 12q15, 12q22, 18q11, and 18q12 in upregulated genes and 14q32 and 16q13 in downregulated genes. The activated GO categories and pathways related to proliferation, adhesion, invasion, and downregulated immune response had been functionally associated with NPC. SLPI significantly downregulated in nasopharyngeal adenocarcinoma. Furthermore, the high expression of BUB1B or CENPF was associated with poor overall survival of patients.

CONCLUSION

It was first clearly identified the dysregulated expression of BUB1B and SLPI in NPC tissues.

IMPACT

Further studies of the CSD genes as gene signatures and molecular markers of NPC might improve the understanding of the disease and identify new therapeutic targets.

Over-expression of Ephb4 is associated with carcinogenesis of gastric cancer

BACKGROUND

Gastric cancer is one of the most frequently diagnosed malignancies in the world. The gene expression profile and molecular grouping of gastric cancer has been a challenging task due to its inherent complexity and variation among individuals.

AIMS

To determine the molecular mechanism associated with gastric carcinogenesis.

METHODS

We analyzed the gene expression profiles of 20 cancerous tissues and their tumor-adjacent tissue from patients with gastric cancer by using a 14 K cDNA microarray. The differentially expressed genes and their products were verified by semiquantitative reverse transcription PCR (RT-PCR), western blotting and immunohistochemistry of gastric cancer and normal tissue samples.

RESULTS

A total of 69 genes were found to be differentially regulated in the cancerous tissue. Among them, genes such as CDH17, ETV4, S100A6, S100A11, Ephb4, and KLK10 were confirmed by RT-PCR to be up-regulated, while genes such as NK4 and PPP2R1B were down-regulated. Western blotting and immunohistochemistry indicated that Ephb4 was over-expressed and localized to the cytoplasm of gastric cancer cells. Moreover, Ephb4 protein was observed as being significantly related to tumor size and pN category (p = 0.001 and 0.007, respectively).

CONCLUSIONS

These newly identified genes might provide a valuable resource for understanding the molecular mechanism associated with the carcinogenesis of gastric cancer and for finding potential diagnostic markers of gastric cancer.

Identification of candidate nasopharyngeal carcinoma serum biomarkers by cancer cell secretome and tissue transcriptome analysis: potential usage of cystatin A for predicting nodal stage and poor prognosis

Nasopharyngeal carcinoma (NPC) is usually diagnosed at advanced clinical stages, resulting in poor outcomes. To discover serum biomarkers for improved NPC diagnosis and/or management, we simultaneously analyzed the NPC cell secretome and tissue transcriptome to identify candidate genes/proteins that are highly upregulated in NPC tissues and also secreted/released from NPC cells. Among the 30 candidates identified, 11 proteins were chosen for further validation using the serum samples from NPC patients and healthy controls, including cystatin A, cathepsin B, manganese superoxide dismutase and matrix metalloproteinase 2. The results showed that serum levels of all the four proteins were indeed higher in NPC patients versus healthy controls and that the use of a three-marker panel (cystatin A, manganese superoxide dismutase and matrix metalloproteinase 2) can contribute to a better NPC detection than each marker alone. In addition, a higher pretreated serum level of cystatin A was found to be associated with a higher nodal stage and poorer prognosis of NPC patients and cystatin A could modulate the migration and invasion of NPC cells in vitro. Altogether, our results indicate that analysis of both the cancer cell secretome and tissue transcriptome is a feasible strategy for efficient identification of novel NPC serum marker panel.

Identification of cellular targets in human intrahepatic cholangiocarcinoma using laser microdissection and accurate mass and time tag proteomics

Obtaining accurate protein profiles from homogeneous cell populations in heterogeneous tissues can enhance the capability to discover protein biomarkers. In this context, methodologies to access specific cellular populations and analyze their proteome with exquisite sensitivity have to be selected. We report here the results of an investigation using a combination of laser microdissection and accurate mass and time tag proteomics. The study was aimed at the precise determination of proteome alterations in intrahepatic cholangiocarcinoma ICC, a markedly heterogeneous tumor. This cancer, which is difficult to diagnose and carries a very poor prognosis, has shown an unexplained increase in incidence over the last few years. Among a pool of 574 identified proteins, we were able to report on altered abundance patterns affecting 39 proteins conforming to a variety of potential tumorigenic pathways. The reliability of the proteomics results was confirmed by Western blot and immunohistochemistry on matched samples. Most of the proteins displaying perturbed abundances had not yet been described in the setting of ICC. These include proteins involved in cell mobility and actin cytoskeleton remodeling, which may participate in the epithelial to mesenchymal transition, a process invoked in migration and invasion of cancer cells. The biological relevance of these findings was explored using a tissue microarray. An increased abundance of vimentin was thus detected in 70% of ICC and none of the controls. These results suggest that vimentin could play a role in the aggressiveness of ICC and provide a basis for the serious outcome of this cancer.

Stage-associated dynamic activity profile of transcription factors in nasopharyngeal carcinoma progression based on protein/DNA array analysis

Transcription factors (TFs) are crucial modulators of gene regulation during the development and progression of tumors. We previously reported the activation of TFs in nasopharyngeal carcinoma (NPC) cell lines. In this study, we explored the activity profiles of TFs in Protein/DNA array data of a 12-tissue independent set and a 13-tissue pooled set of NPC that included different clinical stages. TFs associated with tumor progression were revealed using a generalized linear model-based regression analysis. Immunohistochemical analysis of clinical NPC samples was used to validate the results of array analysis. We identified 26 TFs that showed increased activities. Of these 26 TFs, 16 were correlated with clinical stages. Activity changes of AP2 and ATF/CREB were confirmed by electrophoretic mobility shift assay (EMSA), and increased expression of AP2α, β, γ, ATF2, and ATF1 in nuclei of tumor cells was associated with clinical stages. In addition, the expressions of AP2α, ATF2, and ATF1 were correlated with those of their target genes (epithelia growth factor receptor (EGFR) and matrix metalloproteinase 2 (MMP-2), respectively). This study provides data and valuable clues that can be used to further investigate the laws of gene transcription regulation in NPC and to identify suitable targets for the development of TF-targeted antitumor agents.

From NPC therapeutic target identification to potential treatment strategy

Nasopharyngeal carcinoma (NPC) is relatively rare in Western countries but is a common cancer in southern Asia. Many differentially expressed genes have been linked to NPC; however, how to prioritize therapeutic targets and potential drugs from unsorted gene lists remains largely unknown. We first collected 558 upregulated and 993 downregulated NPC genes from published microarray data and the primary literatures. We then postulated that conversion of gene signatures into the protein-protein interaction network and analyzing the network topologically could provide insight into key regulators involved in tumorigenesis of NPC. Of particular interest was the presence of cliques, called fully connected subgraphs, in the inferred NPC networks. These clique-based hubs, connecting with more than three queries and ranked higher than other nodes in the NPC protein-protein interaction network, were further narrowed down by pathway analysis to retrieve 24 upregulated and 6 downregulated bottleneck genes for predicting NPC carcinogenesis. Moreover, additional oncogenes, tumor suppressor genes, genes involved in protein complexes, and genes obtained after functional profiling were merged with the bottleneck genes to form the final gene signature of 38 upregulated and 10 downregulated genes. We used the initial and final NPC gene signatures to query the Connectivity Map, respectively, and found that target reduction through our pipeline could efficiently uncover potential drugs with cytotoxicity to NPC cancer cells. An integrative Web site (http://140.109.23.188:8080/NPC) was established to facilitate future NPC research. This in silico approach, from target prioritization to potential drugs identification, might be an effective method for various cancer researches.

Expression pattern and prognostic significance of claudins 1, 4, and 7 in nasopharyngeal carcinoma

Claudins are major tight junction proteins that regulate the integrity and function of tight junctions. Aberrant expression of claudins has been shown in various carcinomas with diverse prognostic implications. However, their expression pattern and prognostic value have not been investigated in nasopharyngeal carcinoma. This is the first study to characterize the expression pattern of claudins 1, 4, and 7 in a cohort of 176 patients with nasopharyngeal carcinoma and a minimum follow-up of 9.4 years. Immunohistochemistry with semiquantitative assessment of expression of claudins 1, 4, and 7 was performed on 176 biopsy specimens. Results were correlated with sex, age, extent of tumor, lymph node status, the presence or absence of distant metastasis, and patient survival. High expression of claudins 1 and 4 (72.2% and 88.1%) and low expression of claudin 7 (82.4%) were frequently detected. Low claudin 4 expression (P = .020) and high claudin 7 expression (P < .001) were associated with distant metastasis. Elevated claudin 7 expression also correlated with high tumor stage (P = .001). Furthermore, decreased claudin 4 expression (P = .003) and increased claudin 7 expression (P < .001) independently predicted shorter distant metastasis-free survival by Cox regression analysis. Claudin 4 and claudin 7 may be a novel biomarker for the prediction of distant metastasis and unfavorable prognosis in nasopharyngeal carcinoma.

Upregulated claudin-1 expression confers resistance to cell death of nasopharyngeal carcinoma cells

Accumulating evidence reveals that aberrant expression of claudins manifests in various tumors; however, their biological functions are poorly understood. Here, we report on the elevated expression of claudin-1 in nasopharyngeal carcinoma (NPC) cell lines under serum deprivation or fluorouracil (5-FU) treatment. Interestingly, an increase in expression of claudin-1 considerably reduced apoptosis rather than enhancing cell proliferation. However, claudin-1 expression and activity were unaffected by external stimuli or Akt and NF-kappaB activation. Notably, predominant cytoplasmic and nuclear localization of claudin-1 in NPC cells reflected the aforementioned feature. On the other hand, loss of epithelial morphology and E-cadherin expression was associated with serum withdrawal in NPC cells. Interestingly, restoration of E-cadherin inhibited the protein elevation and antiapoptotic activity of claudin-1. In conclusion, our data demonstrate the regulation and novel biological function of claudin-1 and indicate the important role of claudin-1 in NPC tumorigenesis.

Identification of aberrant cell cycle regulation in Epstein-Barr virus-associated nasopharyngeal carcinoma by cDNA microarray and gene set enrichment analysis

Previous studies have revealed that Epstein-Barr virus (EBV) was closely associated with nasopharyngeal carcinoma (NPC). This study aimed to characterize the global pathways affected in the EBV-associated NPC. Combined with microdissection, gene expression profiles in 22 NPCs and 10 non-tumor nasopharyngeal epithelial (NPE) tissue samples were analyzed. All NPC specimens served in the microarray analysis were positive for EBV, as judged by identification of the expression of EBV nuclear antigen 1 (EBNA1). Through gene set enrichment analysis (GSEA), we found that cell cycle pathway was the most disregulated pathway in NPC (P=0.000, false discovery rate q-value=0.007), which included some aberrant expressed components. We first found that overexpression of CDK4, cyclin D1, and Rb proteins, and loss of expression of proteins p16, p27, and p19 were statistically significant in NPC tissues compared with non-cancerous NPE (P<0.05) by real-time RT-PCR and tissue microarray. EBV-encoded small RNA-1 (EBER-1) hybridization signals in the NPC showed significant associations with the overexpression of Rb (P=0.000), cyclin D1 (P=0.000), CDK4 (P=0.000), and the loss of expression of p16 proteins (P=0.039). In the final logistic regression analysis model, EBER-1 and abnormal expression of p16, Rb, cyclin D1, and E2F6 were independent contributions to nasopharyngeal carcinogenesis. Through survival analysis, only cyclin D1 could predict the prognosis of NPC patients. These results suggested that cell cycle pathway was the most disregulated pathway in the EBV-associated NPC, and EBER-1 was closely associated with p16, CDK4, cyclin D1, and Rb.cyclin D1 could be the prognosis biomarker for NPC.

Dysregulated molecular networks in head and neck carcinogenesis

Multiple genetic and epigenetic events, including the aberrant expression and function of molecules regulating cell signaling, growth, survival, motility, angiogenesis, and cell cycle control, underlie the progressive acquisition of a malignant phenotype in squamous carcinomas of the head and neck (HNSCC). In this regard, there has been a recent explosion in our understanding on how extracellular components, cell surface molecules, and a myriad of intracellular proteins and second messenger systems interact with each other, and are organized in pathways and networks to control cellular and tissue functions and cell fate decisions. This emerging ability to understand the basic mechanism controlling inter- and intra-cellular communication has provided an unprecedented opportunity to understand how their dysregulation contributes to the growth and dissemination of human cancers. Here, we will discuss the emerging information on how the use of modern technologies, including gene array and proteomic studies, combined with the molecular dissection of aberrant signaling networks, including the EGFR, ras, NFkappaB, Stat, Wnt/beta-catenin, TGF-beta, and PI3K-AKT-mTOR signaling pathways, can help elucidate the molecular mechanisms underlying HNSCC progression. Ultimately, we can envision that this knowledge may provide tremendous opportunities for the diagnosis of premalignant squamous lesions, and for the development of novel molecular-targeted strategies for the prevention and treatment of HNSCC.

Epigenetic dysregulation of the host cell genome in Epstein-Barr virus-associated neoplasia

Epstein-Barr virus (EBV), a human herpesvirus, is associated with a wide variety of malignant tumors. The expression of the latent viral RNAs is under strict, host-cell dependent transcriptional control. This results in an almost complete transcriptional silencing of the EBV genome in memory B-cells. In tumor cells, germinal center B-cells and lymphoblastoid cells, distinct viral latency promoters are active. Epigenetic mechanisms contribute to this strict control. In EBV-infected cells, epigenetic mechanisms also alter the expression of cellular genes, including tumor suppressor genes. In Nasopharyngeal Carcinoma, the hypermethylation of certain cellular promoters is attributed to the upregulation of DNA methyltransferases by the viral oncoprotein LMP1 (latent membrane protein 1) via JNK/AP1-signaling. The role of other viral latency products in the epigenetic dysregulation of the cellular genome remains to be established. Analysis of epigenetic alterations in EBV-associated neoplasms may result in a better understanding of their pathogenesis and may facilitate the development of new therapies.

Snail up-regulates proinflammatory mediators and inhibits differentiation in oral keratinocytes

The transcriptional repressor Snail2 is overexpressed in head and neck squamous cell carcinomas (HNSCC) relative to nonmalignant head and neck mucosal epithelium, and in locally recurrent relative to nonrecurrent HNSCCs. We investigated the mechanisms by which Snails might contribute to the pathogenesis of HNSCCs using cell biological and molecular analyses. Oral keratinocytes that expressed Snails acquired an enhanced ability to attract monocytes and to invade a dense interstitial collagen matrix. They were also found to up-regulate production of proinflammatory cytokines and cyclooxygenase-2 (COX2), which have previously been shown to correlate with malignancy. Induction of nuclear factor-kappaB transcriptional activity by Snails was weak and not sufficient to account for the elevated levels of COX2, interleukin (IL)-6, IL8, or CXCL1. In addition, expression of Snails in oral keratinocytes impaired desquamation in vitro and strongly repressed expression of both ELF3 and matriptase-1, which play important roles in the terminal differentiation of keratinocytes. Reexpression of matriptase-1 in Snail-expressing cells partially rescued desquamation. This implicates Snails as contributing to malignancy both at the early stages, by impeding terminal differentiation, and at later stages, when invasion and inflammation are important.

Ligand-based vascular targeting of disease

This review illustrates the basic principles of ligand-based vascular targeting and presents some of the most advanced results obtained in this field, not only in terms of biopharmaceuticals, which are currently being investigated in clinical and preclinical studies, but also in terms of enabling technologies that facilitate target and ligand discovery. Whereas most of the vascular targeting research activities have so far concentrated on tumoral angiogenesis, the development of non-oncological applications has recently gained momentum and is likely to become an important area of modern pharmaceutical research.

Nasopharyngeal carcinoma--review of the molecular mechanisms of tumorigenesis

Nasopharyngeal carcinoma (NPC) is a head and neck cancer rare throughout most of the world but common in certain geographic areas, such as southern Asia. While environmental factors and genetic susceptibility play important roles in NPC pathogenesis, the Epstein-Barr virus in particular has been implicated in the molecular abnormalities leading to NPC. There is upregulation of cellular proliferation pathways such as the Akt pathway, mitogen-activated protein kinases, and the Wnt pathway. Cell adhesion is compromised due to abnormal E-cadherin and beta-catenin function. Aberrations in cell cycle are due to dysregulation of factors such as p16, cyclin D1, and cyclin E. Anti-apoptotic mechanisms are also upregulated. There are multiple abnormalities unique to NPC that are potential targets for novel treatments.

Systemic approach to improving treatment outcome in nasopharyngeal carcinoma: current and future directions

Systemic therapy is an integral part of the management of non-keratinizing nasopharyngeal carcinoma (NPC). The purposes of this review are to provide the latest results and future directions of clinical and translational research for this disease, and to illustrate how some of these new therapies have improved the treatment outcome for patients with NPC. Particular attention will be paid to the clinical application of chemotherapy in the adjunctive treatment of locoregionally advanced NPC, novel targeted drugs, Epstein-Barr virus-targeted vaccine therapies, and the use of plasma Epstein-Barr virus DNA as a biomarker for selecting patients for adjunctive therapies.