CHEN Leilei Polly

CHEN_Leilei_Polly_colorThe main focus of Dr Chen Leilei’s group is to study the transcriptome instability of human cancers, particularly hepatocellular carcinoma (HCC), the major malignancy of the liver and the third leading cause of cancer-related deaths globally. While the epidemiological risk factors for HCC are well known, the molecular mechanisms underlying development of liver cancer are not well characterized. It is especially important to understand the potentially reversible epigenetic mechanisms, since these changes are novel candidates for therapeutic targeting. One type of epigenetic change is RNA editing, defined as an alteration of RNA sequences. Using integrative genomic approaches, her group recently highlighted a link between transcriptome instabilities in the form of excessive or defective RNA editing activity and cancer development. She currently places focus on the regulators of A-to-I RNA editing and the crosstalk between RNA editing and alternative splicing-the two main processes contributing to transcriptome diversity. This work will provide important insights into the regulation of tumorigenesis by transcriptome instability, in turn translating these findings into diagnoses or even treatment.

RNA editing is an integral step in generating the diversity and plasticity of cellular RNA signatures.  In humans, the most frequent type of editing is the conversion of adenosine (A) to inosine (I), which is catalyzed by the double-stranded RNA (dsRNA)-specific ADAR (Adenosine DeAminase that act on RNA) family of protein.  This process of recoding of translated exons, widespread editing of repetitive sequence elements and sequence modification of microRNA (miRNA) can lead to specific amino acid substitutions, alternative splicing and changes in gene expression levels.  With the advent of high-throughput transcriptome sequencing, many editing sites potentially associated with cancer development have been identified.   Our laboratory for the first time demonstrated that unlike other types of cancers, which are associated with a general decrease or increase in RNA editing activity, hepatocellular carcinoma (HCC) displays a more complicated RNA editome, with a disrupted A-to-I editing balance.  We also reported that A-to-I editing of antizyme inhibitor 1 (AZIN1) gene, which is specially catalyzed by a RNA editing enzyme ADAR1, displays a high modification rate in HCC specimens.  As a consequence of RNA editing in AZIN1 transcript, AZIN1 protein undergoing the serine-to-glycine substitution at residue 367, induces a cytoplasmic-to-nuclear translocation, and confers tumor initiating potential and more aggressive behavior (see attached figure).  In addition, we are pursuing work on the biological importance of editing sites within 3’-untranslational region (3’-UTR) during cancer development, such as the effects of editing on transcript stability, microRNA targeting and the subsequent protein expression. Because ADAR enzyme expression imbalances, with consequent editing dysregulation, characterizes many human cancers and, adar1-/- mice are embryonic lethal (at E11.5-12.5) mainly due to defective hematopoiesis and liver disintegration, another focus is to study the role of RNA editing enzyme ADARs and their specific targets in hemoatopoiesis and acute myeloid leukemia (AML). Figure-Polly1

Selected Publications:

  1. Hong HQ, Lin JS, Chen L. Regulatory factors governing Adenosine-to-Inosine (A-to-I) RNA editing. Biosci Rep. 2015 Feb 9. (Epub ahead of print)
  2. Qin YR, Qiao JJ, Chan TH, Zhu YH, Li FF, Liu HB, Fei J, Li Y, Guan XY, Chen L. Adenosine-to-inosine RNA editing mediated by ADARs in Esophageal squamous cell carcinoma (ESCC). Cancer Res. 2014 74(3):840-851.
  3. Chan TH, Lin CH, Qi L, Fei J, Li Y, Yong KJ, Liu M, Song Y, Chow RK, Ng VH, Yuan YF, Tenen DG, Guan XY, Chen L. A disrupted RNA editing balance mediated by ADARs (Adenosine DeAminases that act on RNA) in human hepatocellular carcinoma. Gut. 2014, 63(5):832-43.
  4. Qi LH, Chan HM, Tenen DG, Chen L. RNA editome imbalance in hepatocellular carcinoma. Cancer Res, 2014,74(5):1301-1306.
  5. Qiao JJ, Chan TH, Qin YR, Chen L. ADAR1: a promising new biomarker for Esophageal Squamous Cell Carcinoma. Expert Rev Anticancer Ther, 2014, 14(8):865-868.
  6. Chen L, Li Y, Lin C, Chan TH, Chow RK, Song Y, Liu M, Yuan YF, Fu L, Kong KL, Qi L, Li Y, Zhang N, Tong AH, Kwong DL, Man K, Lo CM, Lok S, Tenen DG, Guan XY. Recoding RNA editing of AZIN1 predisposes to hepatocellular carcinoma. Nature Med, 2013, 19(2):209-16.
  7. Chen L, Fan H, Zhang F, Quan Y, Su X, Qiu X, Zhao Z, Kong KL, Dong S, Song Y, Chan TH, Guan XY. MTSS1, a novel target of DNA methyltransferase 3B, functions as a tumor suppressor in hepatocellular carcinoma. Oncogene. 2012, 31(18):2298-308.
  8. Chen L, Yuan YF, Li Y, Chan TH, Zheng BJ, Huang J, Guan XY. Clinical significance of CHD1L in hepatocellular carcinoma and therapeutic potentials of virus-mediated CHD1L depletion. Gut. 2011, 60(4):534-43.
  9. Chen L, Chan TH, Yuan YF, Guan XY et al. CHD1L promotes hepatocellular carcinoma progression and metastasis in mice and is associated with these processes in human patients. J Clin Invest. 2010, 120(4):1178-91.
  10. Chen L, Hu L, Chan TH, Guan XY et al. Chromodomain helicase/adenosine triphosphatase DNA binding protein 1-like (CHD1l) gene suppresses the nucleus-to-mitochondria translocation of nur77 to sustain hepatocellular carcinoma cell survival. Hepatology. 2009, 50(1):122-9.
Name CHEN Leilei Polly
Affiliations Principal Investigator, Cancer Science Institute of Singapore
NUS President Assistant Professor, Department of Anatomy, NUS
Email csicl[at]nus.edu.sg

Education

Institute Degree (if applicable) Year(s)
Medical College of Jiangsu University, China M.D. (First-Class Honor) 2002
The University of Hong Kong Ph.D. 2010

Professional Experience

Editorial Board member, Journal of Human Transcriptome 2013 – present
Research Fellow in Clinical Oncology, the University of Hong Kong (Laboratory of Prof. Xin-Yuan Guan) 2010 – 2012
Associate Member, American Association for Cancer Research (AACR) 2009 – present
Clinician, Department of Obstetrics and Gynaecology of Nanjing Drum Tower Hospital, China 2005 – 2006

Omer AN

Research Fellow

Transcriptome analysis of cancer RNA-sequencing datasets.

Jaymie LIN Siqi

Research Fellow

Transcriptome instability in the developing liver.

Fernando Bellido MOLIAS

Research Fellow

Assessing the impact of ADAR1 expression on the genomic DNA.

SONG Yangyang

Research Fellow

Investigate RNA editing in Hepatocellular Carcinoma and Liver Differentiation

TANG Sze Jing

Research Fellow

Study Alternative Splicing in Hepatocellular Carcinoma.

Daryl Jin Tai TAY

Research Assistant

Targeting RNA Editing by Triplex-Forming Oligonucleotides (TFOs) or Peptide Nucleic Acid (PNA).

Vanessa Hui En NG

Senior Laboratory Executive

The role of COG3 editing event in human HCC.

Huiqi HONG

PhD student

Elucidating the functional roles of ADAR co-factors in A-to-I RNA editing.

President Assistant Professorship, National University of Singapore 2015
Science and Technology Award of Higher Education of China (Second Class), Ministry of Education, China 2014
NUS Young Scientist Award, National University of Singapore 2014
Finalist in 2014 National Research Fellowship (NRF), Prime Minister’s Office, Singapore 2014
Li Ka Shing Prize 2009/2010, Hong Kong 2010