Am J Cancer Res 2013;3(4):374-389

Original Article
Effect of epigenetic histone modifications on E-cadherin splicing and
expression in lung cancer

Wei Liao, Gwen Jordaan, Minu K Srivastava, Steven Dubinett, Sherven Sharma, Sanjai Sharma

UCLA West Los Angeles VA Medical Center, Division of Hematology Oncology, Los Angeles, California; Molecular Medicine
Laboratory, Veterans Affairs Greater Los Angeles Healthcare System, Los Angeles, California; 3Division of Pulmonary and
Critical Care Medicine, UCLA, Los Angeles, California

Received July 10, 2013; Accepted July 29, 2013; Epub August 14, 2013; Published August 30, 2013

Abstract: We have identified an alternatively spliced, non-functional aberrant E-cadherin transcript that lacks exon 11 and is over
expressed in malignant cells as compared to the normal non-malignant cells. This increase in the aberrant transcript is a
mechanism of loss of E-cadherin gene expression as it is rapidly degraded by the nonsense mediated decay pathway. To study
the mechanism of this gene missplicing we analyzed the role of histone epigenetic modifications in lung cancer cell lines. The
treatment of low E-cadherin lung cancer cell lines with histone deacetylase inhibitor (HDACi, MS-275) resulted in the preferential
expression of the correctly spliced transcripts in the low E-cadherin expressing cell lines only. Chromatin immunoprecipitation
(ChIP) assays revealed that the histone hypoacetylation levels correlate with aberrant exon 11 splicing as there is more aberrant
splicing in cell lines with E-cadherin promoter hypoacetylation. Inactivation of histone deacetylases (HDAC) 1, 2 and 3 resulted in
an increase in E-cadherin expression and an increase in the ratio of the correctly spliced E-cadherin transcript. As transcription
of the gene is closely linked to splicing, we considered the possibility that change in E-cadherin transcription correlates with
splicing. The Zeb1 epithelial-mesenchymal transformation (EMT) inducer silences E-cadherin expression and could also alter
the splicing of this exon. Inhibition of the E-cadherin promoter transcription with Zeb1 expression increases aberrant splicing
and the reverse is observed when Zeb1 is knocked down. The role of HDAC inhibitors was also studied in vivo in a
immunodeficient mouse xenograft model. Exposure of mice to HDACi resulted in growth inhibition, increase in E-cadherin
expression, alteration of aberrant splicing and the reversal of EMT in mouse tumors. The findings support the modulation of
E-cadherin exon 11 inclusion or exclusion by histone epigenetic modifications as they change the overall chromatin structure.
The results provide an interesting link between epigenetic alterations in cancer cells and gene splicing in addition to their effect
on gene silencing. (ajcr0000213).

Keywords: E-cadherin, splicing, histone modifications, HDAC, HDAC inhibitor, Zeb1, EMT

Address correspondence to: Sanjai Sharma, UCLA West Los Angeles VA Medical Center, 11301 Wilshire Blvd, Bldg 304, Rm
E1-115, Los Angeles, CA 90073, USA. Tel: 310-478-3711 ext: 83622; Fax: 310-268-4508; E-mail: sasharma@mednet.ucla.edu
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American Journal of Cancer Research
ISSN: 2156-6976