Lymphoid Enhancing Factor-1(lef-1) Gene Mutation and Its Differential mRNA Expression in Eyelid Sebaceous Carcinoma

Abstract

Purpose: : A higher incidence of Eyelid Sebaceous carcinoma (ESC) is reported from China and India. The molecular mechanisms underlying pathogenesis of ESC are not known. β -catenin signaling pathway has a role in the normal development of sebaceous glands; Lef-1(Lymphoid enhancing factor-1) gene is a key transcription factor and binding partner of β-catenin molecules within the nucleus. Lef-1 encodes two mRNA isoforms (full length and a dominant negative shorter ΔN transcript lacking β-catenin binding domain).The shorter dominant negative transcript have been described in colon cancer. Mutations of Lef-1 have been described in transgenic mice models which lead to spontaneous skin tumors with sebaceous differentiation. The present study was therefore undertaken to determine the role of Lef-1 in the pathogenesis of ESC.

Methods: : Thirty-six cases of histopathologically confirmed ESC diagnosed between2007-2010 were included in this study. Fresh tissues were obtained after informed consent and Institute Ethical Committee approval. Lef-1 immunoexpression using monoclonal antibodies against Lef-1 clone (EP2030Y), at a dilution of (1:50) was evaluated on formalin fixed paraffin embedded sections. Mutational analysis of Lef-1(exon-1, which encodes the β-catenin binding domain) was undertaken by sequencing PCR and Reverse transcription PCR was also performed to assess the differential mRNA expression of Lef-1. The results were correlated with the clinicopathological features.

Results: : Lef-1 mutations in exon-1 were observed in 19% cases (7/36). All 7 samples showed non-sense mutations at codon(27) resulting in amino acid change AAG(Lysine) TAG (stop). Loss of immunohistochemical expression of Lef-1 was seen in 69% cases (25/36) and All cases harboring the Lef-1 mutations were also negative for Lef-1 expression. 6/7 ESC pateints with Lef-1 mutation had advanced age(>60 years), 4/7 were feamles, upperlid was involved in all and 5/7 had tumor size ≥2cm as well as poor histopathologic differentiation. There was no significant correlation of Lef-1 mutations with any of the clinicopathological features. mRNA analysis revealed the variable expression of both long and the short isoforms of Lef-1.

Conclusions: : This preliminary study suggests the possible role of Lef-1 mutations and it’s abnormal mRNA expression in the molecular pathogenesis of Eyelid Sebaceous Carcinoma.However, further studies are needed to elucidate the exact role ofLef-1/β-catenin signalling pathway in it’s pathogenesis.

Keywords: eyelid • tumors • gene/expression