Gene Expression Analysis As a Tool in Early-Stage Oral Cancer Management

Massachusetts General Hospital, Boston, MA.
Journal of Clinical Oncology (Impact Factor: 18.43). 10/2012; 30(33). DOI: 10.1200/JCO.2012.44.8050
Source: PubMed

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    ABSTRACT: Improved understanding of the molecular basis underlying oral squamous cell carcinoma (OSCC) aggressive growth has significant clinical implications. Herein, cross-species genomic comparison of carcinogen-induced murine and human OSCCs with indolent or metastatic growth yielded results with surprising translational relevance. Murine OSCC cell lines were subjected to next-generation sequencing (NGS) to define their mutational landscape, to define novel candidate cancer genes and to assess for parallels with known drivers in human OSCC. Expression arrays identified a mouse metastasis signature and we assessed its representation in 4 independent human datasets comprising 324 patients using weighted voting and Gene Set Enrichment Analysis (GSEA). Kaplan-Meier analysis and multivariate Cox proportional hazards modeling were used to stratify outcomes. A qRT-PCR assay based on the mouse signature coupled to a machine-learning algorithm was developed and used to stratify an independent set of 31 patients with respect to metastatic lymphadenopathy. NGS revealed conservation of human driver pathway mutations in mouse OSCC including in Trp53, MAPK, PI3K, NOTCH, JAK/STAT and FAT1-4. Moreover, comparative analysis between The Cancer Genome Atlas (TCGA) and mouse samples defined AKAP9, MED12L and MYH6 as novel putative cancer genes. Expression analysis identified a transcriptional signature predicting aggressiveness and clinical outcomes, which were validated in 4 independent human OSCC datasets. Finally, we harnessed the translational potential of this signature by creating a clinically feasible assay that stratified OSCC patients with a 93.5% accuracy. These data demonstrate surprising cross-species genomic conservation that has translational relevance for human oral squamous cell cancer.
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    ABSTRACT: High-risk human papillomavirus (HPV) infection is associated with carcinogenesis in oropharyngeal squamous cell carcinoma (OPSCC) and patients with HPV-positive tumors have a significantly favorable prognosis. However, the underlying mechanism of this favorable clinical outcome remains unclear. Epithelial-mesenchymal transition (EMT) causes aggressiveness of cancer cells and we investigated the expression of the EMT markers and analyzed their correlation with HPV status and prognosis in order to examine the treatment response of HPV-positive OPSCCs. A total of 79 patients with OPSCC were examined in the present study. All high-risk HPV infections were determined with the multiplex PCR kit from each formalin-fixed paraffin-embedded (FFPE) sample. We performed immunohistochemical staining for E-cadherin and vimentin. Expression of the markers was graded and we statistically analyzed the correlation between tumor, node, metastasis (TNM) stages and prognosis. High-risk HPV-positive tumors were detected in 23 cases. The five‑year survival rate in HPV-positive and -negative tumors was 82.7 and 48.3%, respectively. High E-cadherin expression rate in HPV-negative samples was 76.7% and 43.4% in HPV-positive samples (p=0.007). Vimentin expression did not show a difference between HPV-positive and -negative tumors. HPV-negative patients presented significantly greater heterogeneity of E-cadherin expression compared to HPV-positive patients (p=0.0349). HPV-positive OPSCCs originally lost their epithelial cell phenotype compared with HPV-negative tumors. Therefore, the paradoxical favorable prognosis of HPV-positive OPSCC may be due to the intratumor homogeneity in EMT.
    Preview · Article · Sep 2014 · Otolaryngology Head and Neck Surgery
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    ABSTRACT: Background: Extracapsular spread (ECS) in cervical lymph nodes is the single-most prognostic clinical variable in oral squamous cell carcinoma (OSCC), but diagnosis is possible only after histopathological examination. A promising biomarker in the primary tumour, alpha smooth muscle actin (SMA) has been shown to be highly prognostic, however, validated biomarkers to predict ECS prior to primary treatment are not yet available. Methods: In 102 OSCC cases, conventional imaging was compared with pTNM staging. SERPINE1, identified from expression microarray of primary tumours as a potential biomarker for ECS, was validated through mRNA expression, and by immunohistochemistry (IHC) on a tissue microarray from the same cohort. Similarly, expression of SMA was also compared with its association with ECS and survival. Expression was analysed separately in the tumour centre and advancing front; and prognostic capability determined using Kaplan-Meier survival analysis. Results: Immunohistochemistry indicated that both SERPINE1 and SMA expression at the tumour-advancing front were significantly associated with ECS (P<0.001). ECS was associated with expression of either or both proteins in all cases. SMA+/SERPINE1+ expression in combination was highly significantly associated with poor survival (P<0.001). MRI showed poor sensitivity for detection of nodal metastasis (56%) and ECS (7%). Both separately, and in combination, SERPINE1 and SMA were superior to MRI for the detection of ECS (sensitivity: SERPINE1: 95%; SMA: 82%; combination: 81%). Conclusion: A combination of SMA and SERPINE1 IHC offer potential as prognostic biomarkers in OSCC. Our findings suggest that biomarkers at the invasive front are likely to be necessary in prediction of ECS or in therapeutic stratification.
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