Shu-Chun Lin

Genome-wide profiling of oral squamous cell carcinoma

Oral squamous cell carcinoma (OSCC) is a common malignancy, the incidence of which is particularly high in some Asian countries due to the geographically linked areca quid (AQ) chewing habit. In this study, array‐based comparative genomic hybridization was used to screen microdissected OSCCs for genome‐wide alterations. The highest frequencies of gene gain were detected for TP63, Serpine1, FGF4/FGF3, c‐Myc and DMD. The highest frequencies of deletion were detected for Caspase8 and MTAP. Gained genes, classified by hierarchical clustering, were mainly on 17q21–tel; 20q; 11q13; 3q27–29 and the X chromosome. Among these, gains of EGFR at 7p, FGF4/FGF3, CCND1 and EMS1 at 11q13, and AIB1 at 20q were significantly associated with lymph node metastasis. The genomic profiles of FHIT and EXT1 in AQ‐associated and non‐AQ‐associated OSCCs exhibited the most prominent differences. RT‐PCR confirmed the significant increase of TP63 and Serpine1 mRNA expression in OSCC relative to non‐malignant matched tissue. A significant increase in Serpine1 immunoreactivity was observed from non‐malignant matched tissue to OSCC. However, there was no correlation between the frequent genomic loss of Caspase 8 and a significant decrease in Caspase8 expression. These data demonstrate that genomic profiling can be useful in analysing pathogenetic events involved in the genesis or progression of OSCC. Copyright

Exploiting salivary miR-31 as a clinical biomarker of oral squamous cell carcinoma

Oral carcinoma is an important malignancy throughout the world. MicroRNAs (miRNAs) are endogenously expressed, non‐coding RNAs that regulate post‐transcriptional levels of targeted mRNAs. MiRNA‐31(miR‐31) is significantly upregulated in oral carcinoma tissues and plays oncogenic roles in oral carcinogenesis.

miR-24 up-regulation in oral carcinoma: Positive association from clinical and in vitro analysis

MicroRNAs (miRNAs) play important roles in neoplastic process. miR-24 is localized on chromosome 9q22 and 19p13, regions frequently altered in oral squamous cell carcinoma (OSCC). This study showed that miR-24 was up-regulated in OSCC tissues relative to control samples. In addition, the plasma levels of miR-24 in OSCC patients were significantly higher than in control individuals. miR-24 expression was also higher in OSCC cell lines relative to normal oral keratinocytes. Experiments blocking miR-24 and using exogenous miR-24 expression indicated that miR-24 contributes to the growth of OSCC cells and that miR-24 may target p57. This study suggests that miR-24 is involved in the regulation of OSCC growth and that the miR-24s level in plasma may be validatable as a tumor marker for OSCC patients.

Polymorphism in heme oxygenase-1 (HO-1) promoter is related to the risk of oral squamous cell carcinoma occurring on male areca chewers.

Areca (betel) chewing is associated with the high incidence of oral squamous cell carcinoma (OSCC) and oral submucous fibrosis (OSF) in Asians. Heme oxygenase-1 (HO-1), encoding an oxidative response protein, plays protective roles in cells. A (GT)n microsatellite repeat in HO-1 promoter shows polymorphisms and modulates the level of gene transcription. We examined allelotypic frequencies of (GT)n repeats in 83 controls, 147 OSCC and 71 OSF. All subjects were male areca chewers. Logistic regression was used to adjust the age confounding for odds ratio (OR). (GT)n repeat polymorphism was classified into short (S), medium (M) and long (L) alleles. The adjusted OR in OSCC subjects carrying L allelotype relative to S allelotype was 1.75. Buccal squamous cell carcinoma (BSCC) is the most common OSCC subset in areca chewers. L allelotype implied the risk of BSCC with adjusted OR of 2.05, whereas M allelotype appeared protective for non-BSCC with adjusted OR of 0.49. Our findings indicated that longer (GT)n repeat allele in HO-1 promoter is associated with the risks of areca-related OSCC, while the shorter (GT)n repeat allele may have protective effects for OSCC.

miR-181 as a putative biomarker for lymph-node metastasis of oral squamous cell carcinoma.

BACKGROUND Oral squamous cell carcinoma (OSCC) is an important malignant disease around the world. Aberrant expression of MicroRNAs (miRNAs) has been implicated in carcinogenesis of various cancers. In previous studies, up-regulation of miR-181 was observed when OSCC progressed from leukoplakia, dysplasia to invasive carcinoma. However, the function of miR-181 in oral tumorigenesis remains unclear. MATERIALS AND METHODS The expression levels of miR-181 in the tissue and plasma of OSCC patients were measured by quantitative RT-PCR. The correlation between miR-181 level and multiple clinical variables were then checked by Mann-Whitney test and Wilcoxon matched pairs test. To study the functional meaning of up-regulated miR-181, migration assay and invasion assay by transwells and colony forming assay were applied to analyze the tumorigenic phenotypes of OSCC cells with ectopical expression of miR-181. RESULTS Among different clinical variables, over-expression of miR-181 was correlated with lymph-node metastasis, vascular invasion, and a poor survival. Functional assays revealed ectopically over-expressed miR-181 would enhance cell migration and invasion, but not the ability of anchorage-independent growth of OSCC cells. In addition, the up-regulation of miR-181 could be detected both in tumor tissues and plasma. CONCLUSION miR-181 may enhance lymph-node metastasis through regulating migration, which could potentially be exploited as a putative biomarker for patients with OSCC.

Areca (betel) nut extract activates mitogen‐activated protein kinasesand NF‐κB in oral keratinocytes

Areca (betel) was recently proved a carcinogenic substance by the International Agency for Research on Cancer. However, the signaling impact of areca in oral keratinocyte is still obscure. Mitogen‐activated protein kinase superfamilies, including extracellular signal‐regulated kinase (ERK), c‐Jun N‐terminal kinases (JNK) and p38, together with transcription factor NF‐κB, are important signaling elements. We examined the activation of these signaling pathways in OECM‐1 and SAS oral keratinocytes, treated with ripe areca nut extract (ANE). In both cells, a rapid increase in JNK1 activity at 0.5 hr was noted following treatment of ANE. ERK was profoundly activated during 0.5–2 hr in OECM‐1 cells. Contrasting p38 activity was noted in these 2 cells. In both cells, ANE also activated NF‐κB pathway in a biphasic manner, particularly for SAS cells. NF‐κB was activated by ∼ 2‐ to 4‐fold at 0.5–1 hr and a plateau or slight decrease of activity existed between 1 and 6 hr. Later, another higher episode of NF‐κB activity was raised. This was accompanied with the rapid degradation in cytosolic IκBα as well as an increase of nuclear NF‐κB in both cells. ANE treatment did not activate epidermal growth factor receptor signaling system, but blockage of NF‐κB activation rendered the suppression of ANE‐modulated COX‐2 upregulation in OECM‐1. This study identified that ANE affected interactive signaling systems in oral keratonocytes that could be the pathogenetic basis for areca.

Array-comparative genomic hybridization to detect genomewide changes in microdissected primary and metastatic oral squamous cell carcinomas

Oral squamous cell carcinoma (OSCC) is a common worldwide malignancy. However, it is unclear what, if any, genomic alterations occur as the disease progresses to invasive and metastatic OSCC. This study used genomewide array‐CGH in microdissected specimens to map genetic alterations found in primary OSCC and neck lymph node metastases. We used array‐based comparative genomic hybridization (array‐CGH) to screen genomewide alterations in eight pairs of microdissected tissue samples from primary and metastatic OSCC. In addition, 25 primary and metastatic OSCC tissue pairs were examined with immunohistochemistry for protein expression of the most frequently altered genes. The highest frequencies of gains were detected in LMYC, REL, TERC, PIK3CA, MYB, MDR1, HRAS, GARP, CCND2, FES, HER2, SIS, and SRY. The highest frequencies of losses were detected in p44S10, TIF1, LPL, MTAP, BMI1, EGR2, and MAP2K5. Genomic alterations in TGFβ2, cellular retinoid‐binding protein 1 gene (CRBP1), PIK3CA, HTR1B, HRAS, ERBB3, and STK6 differed significantly between primary OSCC and their metastatic counterparts. Genomic alterations in PRKCZ, ABL1, and FGF4 were significantly different in patients who died compared with those who survived. Immunohistochemistry confirmed high PIK3CA immunoreactivity in primary and metastatic OSCC. Higher FGF4 immunoreactivity in primary OSCC is associated with a worse prognosis. Loss of CRBP1 immunoreactivity is evident in primary and metastatic OSCC. Our study suggests that precise genomic profiling can be useful in determining gene number changes in OSCC. As our understanding of these changes grow, this profiling may become a practical tool for clinical evaluation.

miR-134 induces oncogenicity and metastasis in head and neck carcinoma through targeting WWOX gene.

Head and neck squamous cell carcinoma (HNSCC) is a prevalent disease worldwide, and the survival of HNSCC has not improved significantly over the last few decades. MicroRNAs (miRNAs) have an important regulatory role during carcinogenesis. Our study investigated the pathogenic implications of miR‐134 in head and neck carcinogenesis. The clinicopathologic implications of miR‐134 in HNSCC were investigated using expression assays and the functional role of miR‐134 in HNSCC pathogenesis was determined using ectopic expression, knockdown and reporter assay experiments. Xenographic tumorigenesis and orthotopic nodal metastasis were assayed in mouse models. In situ hybridization and immunohistochemistry were used to detect the expression of miR‐134 and the WWOX gene in human HNSCC. The results indicated that miR‐134 was upregulated in HNSCC tissues relative to control mucosa. High expression of miR‐134 was associated with nodal metastasis and mortality of patients. Decreased plasma miR‐134 levels after tumor ablation indicated a better prognosis for patients. Multivariate analysis showed that high miR‐134 expression in HNSCC was an independent predictor of poor survival. Ectopic miR‐134 expression significantly enhanced in vitro oncogenic phenotypes and the orthotopic growth and metastasis of HNSCC cells. miR‐134 targeted WW domain‐containing oxidoreductase (WWOX) gene and cell invasion enhanced by miR‐134 expression was abrogated by ectopic WWOX expression in HNSCC cells. miR‐134 expression was reversely associated with the WWOX expression in HNSCC tissues. Evidences from our study substantiated that miR‐134 expression contributes to head and neck carcinogenesis by targeting the WWOX.

Microrna aberrances in head and neck cancer: pathogenetic and clinical significance

Purpose of reviewMicroRNAs (miRNAs) play crucial roles in modulating the neoplastic process of cancers including head and neck squamous cell carcinoma (HNSCC). miRNAs modulate pathogenesis by inhibiting target genes. Understanding how aberrant miRNAs are involved in HNSCC pathogenesis should help to validate potential clinical applications that target these entities. Recent findingsmiR-21, miR-31, miR-504 and miR-10b are important oncogenic miRNAs that are involved in HNSCC and target tumour suppressor genes. The tumour suppressor roles of the let-7 family, the miR-99 family, miR-107, miR-133a, miR-137, miR-138 and miR-375 with respect to their targeting of oncogenes are unequivocal and have been confirmed by many studies. In addition, miR-21, let-7, miR-107, miR-138 and miR-200c seem to play complicated roles in regulating stemness or the epithelial-mesenchymal transition of tumour cells. The clinical implications of these tumour-associated miRNAs are generally in agreement with their functional roles. SummaryA number of pathways that become disregulated by aberrant miRNAs have been identified specifically for HNSCC. Analysis of these networks and their therapeutic interception might facilitate the prediction of disease status and help with the design of therapeutic trials.

Association of Expression Aberrances and Genetic Polymorphisms of Lysyl Oxidase with Areca-Associated Oral Tumorigenesis

Purpose: Areca nut use is the major cause of oral squamous cell carcinoma (OSCC) in Southern Asians. Areca nut contains a high level of free copper ions. Lysyl oxidase (LOX) is a copper-activated enzyme critical for extracellular matrix organization. Contradictory evidence has been put forward to suggest that LOX may be either an oncogenic or a suppressive element. This study investigated the oncogenic significance of LOX in areca-associated OSCC. Experimental Design: The expression assays and polymorphism analysis were done to know the clinicopathologic implications of LOX status in OSCC. Knockdown and overexpression experiments were conducted to know the phenotypic effects of LOX on OSCC cells. Results: Up-regulation of LOX mRNA and LOX protein expression in OSCCs relative to adjacent oral mucosa was found. Precancerous lesions had the highest LOX mRNA expression. Areca nut extract up-regulated LOX expression in oral epithelial cells. Knockdown of LOX induced cellular migration and invasion, but it reduced the anchorage-independent growth and xenographic tumorigenesis of OSCC cells. The reduction of migration and invasion by LOX overexpression was partially rescued by blockage of LOX activity. The Arg158Gln polymorphism was associated with earlier clinical stage of OSCC. Wild-type LOX overexpression induced anchorage-independent growth in OSCC cells, but this was not for LOXArg158Gln overexpression. Conclusion: LOX exerts oncogenic roles in areca-associated OSCC. This potential could be affected by the existence of LOX propeptide domain or genetic polymorphism.