Hypermethylation of the RECK gene predicts poor prognosis in oral squamous cell carcinomas
ABSTRACT The RECK gene is a novel tumor suppressor gene that regulates matrix metalloproteinases (MMPs) to inhibit tumor angiogenesis, invasion and metastasis. We investigated the methylation status of the RECK gene in 40 primary oral squamous cell carcinomas (OSCC) and 20 paired adjacent normal mucosa by methylation-specific PCR. Furthermore, we determined the prognostic importance of RECK hypermethylation in OSCC patients. Our findings showed that the RECK gene was methylated in 52.5% (21 of 40) of the primary OSCC. Among the 20 cases with corresponding normal tissues, RECK hypermethylation was detected in both primary tumor (55%, 11 of 20) and adjacent normal mucosa (30%, 6 of 20). Methylation of the RECK gene was not detected in all normal oral mucosa samples of the 12 healthy controls. In univariate analysis, RECK hypermethylation was inversely correlated with recurrence-free survival (p=0.027) and overall survival (p=0.023) of the OSCC patients. Multivariate analysis showed that the methylation status of the RECK gene was the only independent prognostic factor affecting overall survival (p=0.037). The result indicates that hypermethylation of RECK promoter is a common event in human OSCC, occurs concurrently in tumor-adjacent normal mucosa and is correlated with poor prognosis in OSCC patients. Although additional work is needed, hypermethylation of the RECK gene is a promising biomarker in early detection and prognosis for oral cancer patients.
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ABSTRACT: In our model, we aimed to explore the cytotoxicity of 5-Aza-2'-deoxycytidine (5-Aza-CdR) against the colorectal cell line, Lovo, and further characterize the possible mechanisms. After Lovo cells were treated with 5-Aza-CdR at different concentrations for different periods of time, the cell viability was examined using an MTT assay and apoptosis was examined using both flow cytometry and DNA laddering. To examine the mechanisms by which Lovo cells respond to 5-Aza-CdR, we measured both caspase 3 activity as well as DNA damage. Western blotting and RT-PCR assays were used to assess the changes in the expression levels of P53, P21(Waf1/Cip1), runt-related transcription factor 3 (RUNX 3), DNA methyltransferases (DNMTs) and matrix metalloproteinases (MMPs). Additionally, we performed gelatin zymography to examine the effects of 5-Aza-CdR on metastasis. We observed that the growth and survival advantages of Lovo cells were overcome with 5-Aza-CdR treatment at limited concentrations. Mechanistic exploration demonstrated that 5-Aza-CdR was incorporated into the DNA to induce DNA damage in Lovo cells, which was evidenced by activation of P53, P21(Waf1/Cip1) and a caspase-independent cell apoptosis pathway. Also, further experiments preliminarily suggested that 5-Aza-CdR results in the deletion of DNMT 3a and DNMT 3b, but not DNMT 1, which reactivates the expression of RUNX 3. Finally, our data revealed that 5-Aza-CdR potentially reduces the activity and expression of MMP 2. These data greatly enhance our understanding of how human cancer cells respond to 5-Aza-CdR and also reveal a new role for 5-Aza-CdR in improving patient outcome in human colorectal cancer.Life Sciences 02/2009; 84(9-10):311-20. DOI:10.1016/j.lfs.2008.12.015 · 2.30 Impact Factor
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ABSTRACT: This paper provides a synopsis of the main papers on diagnosis, imaging, treatment, prognostication and treatment outcomes in patients with oral and oropharyngeal squamous cell carcinoma (OSCC) and head and neck SCC (HNSCC) published in 2008 in Oral Oncology - an international interdisciplinary journal which publishes high quality original research, clinical trials and review articles, and all other scientific articles relating to the aetiopathogenesis, epidemiology, prevention, clinical features, diagnosis, treatment and management of patients with neoplasms in the head and neck, and orofacial disease in patients with malignant disease.Oral Oncology 03/2009; 45(6):e25-30. DOI:10.1016/j.oraloncology.2008.12.011 · 3.03 Impact Factor
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ABSTRACT: The hamster buccal pouch (HBP) carcinogenesis model is one of the most well characterized animal systems for analyzing the development of oral squamous cell carcinoma (OSCC), a common malignancy worldwide. HBP carcinomas that closely mimic human OSCC are useful in understanding the molecular mechanisms of neoplastic transformation. The present study is a comparative evaluation of markers of carcinogen activation, oxidative stress, cell proliferation, apoptosis, invasion, and angiogenesis in human and hamster OSCCs. Enhanced expression of CYP1A1 and CYP1B1 isoforms in both human and hamster oral tumours was associated with significantly increased expression of 8-hydroxy 2-deoxyguanosine (8-OHdG) indicating oxidative DNA damage. Analysis of markers of cell survival and proliferation revealed increased expression of PCNA, GST-P, and NF-kappaB with downregulation of p21, p53 and IkappaB in both human and hamster OSCCs. In addition, both human and hamster oral carcinomas displayed invasive, and angiogenic properties as revealed by dysregulated cytokeratin expression, downregulation of RECK, and increased expression of uPA, MMP-2 and-9, HIF-1alpha, and VEGF. The results reveal aberrant expression of multiple molecules in key signaling pathways in both human OSCCs and HBP carcinomas rendering the HBP model as an important tool for monitoring oral oncogenesis.Oral Oncology 03/2009; 45(6):e31-7. DOI:10.1016/j.oraloncology.2009.01.006 · 3.03 Impact Factor