Molecular analysis of the fragile histidine triad <i>(FHIT)</i> tumor suppressor gene in vesical tumors of cattle with chronic enzootic hematuria (CEH)

Abstract

The FHIT (fragile histidine triad) gene is a tumor suppressor gene known to be inactivated in many tumors including bladder tumors and is spanning FRA3B, a very active common fragile site in the human genome. We have recently isolated the bovine gene, and the aim of this study was to test whether FHIT presents altered expression patterns in vesical tumors of cattle with CEH (chronic enzootic hematuria). CEH is a common syndrome affecting Mediterranean cattle: clastogenic, mutagenic and cancerogenic substances released by the bracken fern (Pteridium spp) grazed by animals induce the formation of neoplastic lesions, among which bladder tumors have a high incidence. We analysed FHIT in 23 bladder tumors of CEH cattle looking at: 1) the methylation status of the CpG island comprising the promoter and part of exon 1; 2) the presence of altered FHIT transcripts; 3) the mRNA expression levels measured with a quantitative real time PCR (QRT-PCR) approach. Our results suggest that unlike in human tumors, FHIT in vesical tumors of CEH cattle is largely unmethylated. Furthermore, the same mRNA isoforms of FHIT were detected in tumors and in healthy tissues, including a novel isoform that was found in this study. Finally, QRT-PCR data did not reveal significantly altered expression profiles of FHIT transcripts. Further studies and larger sets of cases will be useful to confirm this finding, but the data seem to suggest that epigenetic modifications of FHIT and altered expression profiles are not a hallmark of bovine vesical tumors like they are in human tumors.

Molecular and epigenetic analysis of the fragile histidine triad tumour suppressor gene in equine sarcoids

“…Figure 4A shows the 5' FHIT transcript organisation in the horse genome. The equine FHIT 5'UTR region organization is comparable with the data deriving from other species such as Bos [17]. The DNA sequences of both transcripts have been deposited in GenBank [JN403048, JN403049].…”

“…In a variable percentage of cases, depending on the tumour type, FHIT loss of function is determined by the hypermethylation status of the associated CpG island with the consequent repression of gene transcription [11]. While alterations in the FHIT gene have been reported in several human cancers, the putative role of this tumour suppressor gene and its epigenetic alteration in animal tumours are not well known [17,18]. In order to obtain new insights into BPV-mediated carcinogenesis, we investigated the status of FHIT protein expression in equine sarcoid cell lines and sarcoid tumours.…”

Bovine papillomavirus: opening new trends for comparative pathology

“…Interestingly, the number of viral DNA copies has been shown to be significantly higher in more aggressive sarcoids, compared with their slowgrowing counterparts [33]. Over the years, the expression of several cancer markers has been studied in equine sarcoids, such as the tumour suppressor gene fragile histidine triad (FHIT), which was found to be down-regulated [34] as in human cervical cancer [35] although, curiously, not in BPV-associated bovine urinary tumours [36]. Such differences make spontaneous, BPV-induced, animal cancer models particularly useful to study the influence of specific host's genes in the carcinogenic process.…”

Fragile histidine triad protein: structure, function, and its association with tumorogenesis

“…On the other hand, it was suggested that the promoter gene methylation of FHIT is one of the reasons for inactivation mechanisms of suppressor activity (Stam et al 2006;Guidi et al 2008).…”