Fhit expression in human gastric adenomas and intramucosal carcinomas: correlation with Mlh1 expression and gastric phenotype

FHIT Oncosuppressor Gene Expression Profile in Human Anal Cancers

The FHIT gene, a member of the histidine triad gene family, is a tumor suppressor gene exhibiting deletions in the majority of human cancers. Aberrant transcripts of this gene have been found in about 50% of esophageal, stomach and colon carcinomas. Little is known about the molecular mechanisms involved in malignant transformation of the lining cells of the anus. In this study FHIT gene expression was investigated in this particular kind of human cancer. FHIT expression was comparatively analyzed at the mRNA level, by RT-PCR, in squamous anal cancers, normal anal tissue and peripheral blood samples. cDNA analyses showed variability in FHIT transcripts, without apparent effects on the predicted amino acid sequence. These different FHIT mRNAs could represent transcripts from an alternative splicing event. Our data indicate that the FHIT mRNA detected in anal cancers and in normal samples is heterogeneous. Immunohistochemical data suggest that the Fhit protein is expressed only in a fraction of the tumor cells, while it is strongly expressed in the epithelial cells of glands of the normal anal mucosa. The absence or poor expression of the Fhit protein in anal cancers suggests a role for this tumor suppressor gene product, as a risk factor, in the onset of this human cancer, as reported before for other human gastrointestinal tumors.

FHIT down-regulation was inversely linked to aggressive behaviors and adverse prognosis of gastric cancer: a meta- and bioinformatics analysis

FHIT (fragile histine triad) acts as diadenosine P1, P3-bis (5'-adenosyl)-triphosphate adenylohydrolase involved in purine metabolism, and induces apoptosis as a tumor suppressor. We performed a systematic meta- and bioinformatics analysis through multiple online databases up to March 14, 2017. The down-regulated FHIT expression was found in gastric cancer, compared with normal mucosa and dysplasia (p < 0.05). FHIT expression was negatively with depth of invasion, lymph node metastasis, distant metastasis, TNM staging and dedifferentiation of gastric cancer (p < 0.05). A positive association between FHIT expression and favorable overall survival was found in patients with gastric cancer (p < 0.05). According to Kaplan-Meier plotter, we found that a higher FHIT expression was negatively correlated with overall and progression-free survival rates of all cancer patients, even stratified by aggressive parameters (p < 0.05). These findings indicated that FHIT expression might be employed as a potential marker to indicate gastric carcinogenesis and subsequent progression, even prognosis.

Premalignant lesions in gastric cancer

Despite a plateau in incidence, gastric cancer is one of the most common cancers worldwide and causes considerable morbidity and mortality. Premalignant gastric lesions are well known risk factors for the development of intestinal-type gastric adenocarcinomas. In this multistep model of gastric carcinogenesis, Helicobacter pylori causes chronic active inflammation of the gastric mucosa, which slowly progresses through the premalignant stages of atrophic gastritis, intestinal metaplasia, and adenoma/dysplasia to gastric carcinoma. This progression is paralleled by a stepwise accumulation of multiple genetic and epigenetic abnormalities. Detection, treatment, and molecular analyses of premalignant lesions may thus provide a basis for gastric cancer prevention. This review describes an overview of current knowledge on premalignant gastric lesions. It also reviews the issue of surveillance of patients with premalignant lesions in order to improve the survival of patients with gastric cancer.

Immunohistochemical assessment of Fhit protein expression in advanced gastric carcinomas in correlation with Helicobacter pylori infection and survival time

Fhit protein is known to play a role in the process of neoplastic transformation. It has been demonstrated that FHIT gene inactivation is manifested by a lack or very low concentration of Fhit protein in tissues collected from tumours in many organs, including head, neck, breast, lungs, stomach or large intestine. The study included a group of 80 patients with advanced gastric carcinomas. The expression of Fhit protein was assessed by means of the immunohistochemical method (avidin-biotin-streptavidin) in the sections fixed in formalin and embedded in paraffin, using rabbit polyclonal antiFhit antibody (Abcam, UK) at 1: 200. Statistical analysis did not show any correlation of the expression of Fhit protein in the main mass of tumour and in the metastasis to lymph node with gender, depth of wall invasion, histological differentiation, Lauren's classification, Bormann's classification, metastases to local lymph nodes or Helicobacter pylori infection. However, a strong statistical correlation was revealed of Fhit protein expression in the main mass of tumour with patients' age (p=0.04) and tumour location in the stomach (p=0.02). No relationship was found between Fhit expression in the main mass of tumour and survival time (p=0.26).

Common fragile genes and digestive tract cancers

FRA3B and FRA16D are the most sensitive common chromosomal fragile site loci in the human genome. Two tumor suppressor genes, the fragile histidine triad (FHIT) gene and the WW domain-containing oxidoreductase (WWOX), map to the common fragile sites, FRA3B and FRA16D, respectively. Interestingly, FHIT and WWOX have similarities: for example, they are both larger than 1 Mb and encompass fragile sites, they both show frequent allelic loss regions in various human cancers, they both span a region of homozygous deletion in multiple cancers, and they both frequently show aberrant transcripts. The development of human cancers, including digestive tract cancers, is strongly associated with exposure to environmental carcinogens. Common fragile sites are very sensitive to this type of exposure, and the resulting DNA damage leads to the inactivation of genes such as FHIT and WWOX. We present an overview of these two common fragile genes, namely FHIT/FRA3B and WWOX/FRA16D, in digestive tract cancers.

Loss of Fhit expression is associated with poorer survival in gastric cancer but is not an independent prognostic marker

Several studies have reported conflicting results regarding correlations of the loss of Fhit expression with clinicopathological parameters in gastric cancer. We investigated the immunohistochemical expression of Fhit in 362 cases of sporadic advanced gastric adenocarcinoma. The series included 64 cases with microsatellite instability associated with defective mismatch repair genes. Fhit expression resulted absent in 72% of the tumors analyzed. Absence of Fhit expression was more frequent in cases with diffuse and mixed histotype compared to the intestinal histotype (P=0.009). Absence of Fhit expression also correlated with tumor stage (P<0.001), lymph node involvement (P<0.001), presence of distant metastasis (P=0.033), and increasing histological grade (P=0.005). Retained Fhit expression also correlated with microsatellite instability as 61% of instable tumors had lost Fhit expression compared to 74% of microsatellite stable cancers (P=0.050). While loss of Fhit correlates with poorer survival in univariate analysis, it is not an independent prognostic factor in multivariate analysis and is thus not of clinical utility.