22] THE KLF6 (IVS1-27G > A) POLYMORPHISM IS ASSOCIATED WITH NON-PROGRESSIVE NAFLD

Abstract

Background: Kruppel like factor 6 (KLF6) is a zinc finger transcription factor and candidate tumour suppressor first identified as an immediate early gene in injured hepatic stellate cells (HSC). It also upregulated in association with oxidative stress and increased TGFbetal levels in animals with steatohepatitis induced by a methionine-choline deficient (MCD) diet and is a proposed mediator of progressive inflammation and fibrosis. We have recently identified a KLF6 polymorphism (KLF6-IVS I-27G >A) associated with alternative splicing to dominant negative KLF6 isoforms and an increased incidence of familial prostate cancer. The aim of this study was to assess the prevalence of KLF6-1VS1-27G > A in patients with NAFLD. Patients and Methods: We enrolled 3 12 Caucasian patients with NAFLD. Grading and staging of steatosis, inflammation and fibrosis were as defined by Brunt. A 290 base pair amplicon was generated from peripheral blood DNA using primers spanning the SNP in KLF6 intron 1. The enzyme BsaA I cuts at the ‘CGCG’ of the wild type sequence. Results: The frequency of KLF6-IVS1-27G > A (rs3750861 I ) was 15% in a European population studied in the International HapMap project. The G > A allele was similarly present in 451312 (14.4%) of our patients with NAFLD. However, when considering patients with minimal versus advenced fibrosis the incidence was 18% versus 8%. As a group, the KLF6 heterozygotes had significantly less advanced fibrosis (p 0.05), with 76% having stage 0 or 1 disease, versus 57% of wt individuals. The odds ratio for development of advanced fibrosis in KLF6 wt versus heterozygous individuals was 2.4 [CI 0.93-4.31. Discussion: Induction of KLF6 expression in HSC in response to liver injury contributes to their activation. Induction associated with an increased ratio of dominant negative KLF6 splice forms, sequestering KLF6 in the cytoplasm, may well inhibit this and subsequent pro-fibrogenic processes. In view of the recently postulated link between hepatocyte senescence and fibrosis, it is also possible that KLF6-IVS I-27G > A impedes progressive disease by facilitating hepatocyte regeneration in the face of chronic injury. A polymorphism associated with more rapid tumour growth and familial cancers may therefore have beneficial effects in promoting cell survival in a non-cancer, chronic disease situation.