AsianScientist (Jan. 16, 2014) – Esophageal squamous cell carcinoma (ESCC), the major histological form of esophageal cancer, is the leading cause of cancer death worldwide.
Scientists from the National University of Singapore (NUS) have discovered that a biomarker called adenosine deaminase acting on RNA-1 (ADAR1) is significantly over-expressed in ESCC tumors.
The study, published in Cancer Research and led by Dr. Polly Chen from the Cancer Science Institute of Singapore, is also the first to demonstrate that the editing of protein-making sequences promotes the development of ESCC.
Currently, there is poor prognosis for ESCC patients and the five-year survival rate ranges from 20 to 30 percent. There is an urgent need for biomarkers which can diagnose this disease as early as possible and estimate the efficacy of chemotherapy or radiotherapy treatments in patients.
Editing is a process in which RNA is changed after it is made from DNA, resulting in an altered gene product. RNA editing is likely to play a role in the formation of tumors by either inactivating a tumor suppressor or activating genes that promote tumor progression.
In their study, the researchers discovered that the RNA editing enzyme ADAR1 changes the product of the AZIN1 protein to a form that promotes the development of the disease. Clinically, over-expression of ADAR1 in tumors was correlated with the shorter survival time of ESCC patients.
The findings suggest that ADAR1 can serve as a useful biomarker to detect disorders leading to ESCC and as a potential therapeutic target, by silencing ADAR1 and reinstating a specific hyper-edited or hypo-edited transcript.
“Investigating the connection between ADAR1-mediated RNA editing and cancer progression is only the initial step in this research. The tumoral over-expression of ADAR1 can be used as an early warning sign of ESCC and halting or reversing the process may block the cells’ conversion from normal to malignant,” said Dr. Chen.
The article can be found at: Qin Y et al. (2013) Adenosine-to-Inosine RNA Editing Mediated by ADARs in Esophageal Squamous Cell Carcinoma.
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Source: National University of Singapore; Photo: euthman/Flickr/CC.
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