Research Papers:
TWIST1 and TWIST2 promoter methylation and protein expression in tumor stroma influence the epithelialmesenchymal transitionlike tumor budding phenotype in colorectal cancer
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José A. Galván1,*, Melina Helbling1,*, Viktor H. Koelzer1,2, Mario P. Tschan3, Martin D. Berger4, Marion Hädrich5, Beat Schnüriger5, Eva Karamitopoulou1,2, Heather Dawson1,2, Daniel Inderbitzin5,6, Alessandro Lugli1,2, Inti Zlobec1
1Translational Research Unit (TRU), Institute of Pathology, University of Bern, Bern 3010, Switzerland
2Clinical Pathology Division, Institute of Pathology, University of Bern, Switzerland
3Experimental Pathology Division, Institute of Pathology, University of Bern, Switzerland
4Department of Medical Oncology, Bern University Hospital, Bern, Switzerland
5Departments of Visceral Surgery and Medicine, Bern University Hospital, Bern, Switzerland
6Department of Surgery, Tiefenau Hospital, Bern, Switzerland
*These authors have contributed equally to this work
Correspondence to:
Inti Zlobec, e-mail: [email protected]
Keywords: tumor microenvironment, methylation, budding, pyrosequencing, Twist
Received: September 24, 2014 Accepted: November 08, 2014 Published: November 26, 2014
ABSTRACT
Tumor budding in colorectal cancer is likened to an epithelial-mesenchymal transition (EMT) characterized predominantly by loss of E-cadherin and up-regulation of E-cadherin repressors like TWIST1 and TWIST2. Here we investigate a possible epigenetic link between TWIST proteins and the tumor budding phenotype. TWIST1 and TWIST2 promoter methylation and protein expression were investigated in six cell lines and further correlated with tumor budding in patient cohort 1 (n = 185). Patient cohort 2 (n = 112) was used to assess prognostic effects. Laser capture microdissection (LCM) of tumor epithelium and stroma from low- and high-grade budding cancers was performed. In colorectal cancers, TWIST1 and TWIST2 expression was essentially restricted to stromal cells. LCM results of a high-grade budding case show positive TWIST1 and TWIST2 stroma and no methylation, while the low-grade budding case was characterized by negative stroma and strong hypermethylation. TWIST1 stromal cell staining was associated with adverse features like more advanced pT (p = 0.0044), lymph node metastasis (p = 0.0301), lymphatic vessel invasion (p = 0.0373), perineural invasion (p = 0.0109) and worse overall survival time (p = 0.0226). Stromal cells may influence tumor budding in colorectal cancers through expression of TWIST1. Hypermethylation of the tumor stroma may represent an alternative mechanism for regulation of TWIST1.