Cancer biology, Cancer metastasis, Epigenetic regulation, Signal transduction, Cancer drug pharmacology, non-coding RNA
Dr. Shiah’s research interests focuses on these fields:
- Identify the dysregulated miRNAs in oral cancer: genetic and epigenetic links in risk factors or micro-environmental regulation.
- Investigate the role of inflammation-related miRNAs in oral cancer.
- Study the role and function of exosome miRNAs in oral squamous cell carcinoma (OSCC).
- Discover the diagnostic and prognostic potential miRNAs in OSCC.
- Identify saliva miRNAs for OSCC screening, early detection and diagnosis.
RESEARCH ACTIVITIES & ACCOMPLISHMENT
Oral cancer, predominantly oral squamous cell carcinoma (OSCC), is the most common head and neck cancer worldwide, with more than 300,000 new cases being diagnosed annually. Despite advances in therapy, the 5-year survival rate for OSCC has not improved markedly over the past years, due to late diagnosis and frequent loco-regional recurrences at the primary site and the metastatic neck lymph node after treatment. Therefore, molecular signatures that predict disease prognosis and a deeper understanding of the molecular mechanisms of OSCC tumorigenesis are urgently needed to improve therapeutic efficacy, as well as to design more effective treatment strategies for OSCC.
Over the last decade, accumulating evidence highlights the miRNAs may actually play a much larger role in the initiation and progression of oral cancer. An accumulating body of data suggests that the two major risk factors, smoking and alcohol consumption have a direct impact on the dynamic regulation of gene expression in OSCC. However, the molecular mechanisms involved in the pathogenesis of betel quid chewing-associated oral cancer remain largely unknown.
Based our previously studying, we have documented some important finding:
1. Identify the dysregulated miRNAs in oral cancer: genetic and epigenetic links in risk factors or micro-environmental regulation:
(1) Identification of oral carcinoma miRNA involved in Wnt/β-catenin signaling.
Aberrant miRNA expression patterns have been widely reported in various cancer types. In this study, we identified a large group of OSCC-associated miRNA clusters located on the chromosome 14q32.2 region and within a parentally imprinted domain designated Dlk1-Dio3. Bioinformatic analysis predicted two miRNAs, miR-329 and miR-410, from the cluster region could potentially target the Wnt-7b, an activator of the Wnt/β-catenin pathway, consequently, attenuation of Wnt/β-catenin signaling pathway. Our findings define the relationship between the miR-329/-410 and the Wnt/β-catenin pathway, which implies functional mechanisms for miR-329 and miR-410 in oral carcinogenesis. Importantly, the dysregulation of the Meg-3/miR-329&410/Wnt-7b/β-catenin signaling axis may result from exposure to betel quid chewing. Our results thus provide a novel molecular insight into how betel quid may contribute to oral carcinogenesis through the epigenetic silencing of tumor suppressor miRNAs targeting the Wnt/β-catenin signaling pathway.
(2) IL-8 induces miR-424-5p expression and modulates SOCS2/STAT5 signaling pathway in oral squamous cell carcinoma.
Suppressor of cytokine signaling (SOCS) proteins are negative feedback regulators of the Janus kinase/signal transducer and activator of transcription (JAK/STAT) pathway. Dysregulation of SOCS protein expression in cancers can be one of the mechanisms that maintain STAT activation, but this mechanism is still poorly understood in oral squamous cell carcinoma (OSCC). Here, we report that SOCS2 protein is significantly downregulated in OSCC patients and its levels are inversely correlated with miR-424-5p expression. We identified the SOCS2 protein, which modulates STAT5 activity, as a direct target of miR-424-5p. The miR-424-5p-induced STAT5 phosphorylation, matrix metalloproteinases (MMPs) expression, and cell migration and invasion were blocked by SOCS2 restoration, suggesting that miR-424-5p exhibits its oncogenic activity through negatively regulating SOCS2 levels. Furthermore, miR-424-5p expression could be induced by the cytokine IL-8 primarily through enhancing STAT5 transcriptional activity rather than NF-κB signaling. Antagomir-mediated inactivation of miR-424-5p prevented the IL-8-induced cell migration and invasion, indicating that miR-424-5p is required for IL-8-induced cellular invasiveness. Taken together, these data indicate that STAT5-dependent expression of miR-424-5p plays an important role in mediating IL-8/STAT5/SOCS2 feedback loop, and scavenging miR-424-5p function using antagomir may have therapeutic potential for the treatment of OSCC.
(3) miR-376c Inhibits Head and Neck Squamous Cell Carcinoma Lymphatic Metastasis by Controlling the RUNX2-INHBA Axis.
Aberrant microRNA (miRNA) expression is a common phenotype in cancer cell progression. miRNAs are negative regulators that fine-tune the expression of hundreds to thousands of genes. Here, we report that the chr14q32.2 miRNA cluster is significantly down-regulated in clinical head and neck squamous cell carcinoma (HNSCC) samples. Twenty miRNAs exhibited coordinated silencing in HNSCC tumors, with miR-376c being the most dominant. Ectopic miR-376c expression in HNSCC cells inhibited not only the migration and invasion of head and neck cancer cells in vitro but also lymphatic metastasis in Nod-SCID mice in vivo. In HNSCC, miR-376c binds directly to the 3’-UTR of the key oncogenic transcription factor RUNX2. RUNX2 is the master regulatory up-stream transcription factor among HNSCC patients, and miR-376c acts as a negative regulator of RUNX2. Thus, restoring RUNX2 expression may abolish the tumor suppressor activity of miR-376c. Furthermore, we confirmed the reverse correlation between miR-376c and RUNX2 mRNA levels in HNSCC patients. In HNSCC, we showed that RUNX2 controls HNSCC metastasis through the induction of INHBA expression. The combined expression of miR-376c and INHBA could serve as a marker of poor prognosis in HNSCC patients. Taken together, our findings demonstrate the tumor suppressor role of miR-376c, which regulates the RUNX2-INHBA axis in HNSCC progression.
2. miRNA biomarkers discovery:
(1) Identification of miRNAs as diagnostic biomarkers in OSCC.
Our goal was to obtain several panels of microRNA probes that can accurately differentiate oral tumor tissues from their adjacent normal ones. To do this, we performed Illumina’s microRNA array or qPCR quantification techniques to obtain microRNA expression profiles of 130 oral cancer patients. By building univariate logistic regression model based on training set data and use it to predict test set samples, a panel of 16 probes with very good potential of prediction (AUC > 0.9) can be obtained. We therefore select several top ranked probe sets (n=6; top 4-9) to build multivariate logistic regression models based on the previous mentioned 90 samples, to predict another set of 40 new samples from the independent cohort. Five miRNA sets obtained in this study capable of discriminating oral cancerous tissues from normal tissues All of them had AUC >0.9. These results consistently indicate that those panels of microRNA probe sets are potential to be used as markers to differentiate cancerous from normal tissues of oral cavity.
(2) Identification of miRNAs as saliva biomarkers in early detection of OSCC.
In this project, we want to development of saliva miRNA as biomarker for quick diagnosis of malignant transformation of oral potentially malignant disorders (OPMD). So far, we have collected 200 saliva samples (63 for normal, 61 for OPMD and 76 for OSCC) for this purpose. After small RNA sequencing, we have got 45 differential expression miRNA for early detection candidates. Next step, we will validate these miRNA candidates from experimental verified procedure. We hope to establish reliable biomarkers of malignant precancerous lesions for early detection.