Fragile Histidine Triad Promoter Research Articles

Relationship between Methylation of FHIT and CDH13 Gene Promoter Region and Liver Cancer.

In order to demonstrate the relationship between methylation of fragile histidine triad (FHIT) and T-cadherin/H-cadherin (CDH13) genes and liver cancer, the methylation status of FHIT and CDH13 was detected in healthy individuals and in Mongolian and Han patients with liver cancer. The phenol-chloroform method was used to extract genomic DNA. The methylation specific polymerase chain reaction method was applied to detect the methylation status of FHIT and CDH13. The relationship between smoking and alcohol consumption and gene (FHIT and CDH13) methylation was analyzed. There was significant difference in methylation rate of FHIT (72.67%, 34.67%) and CDH13 (72.0%, 28.0%) between liver cancer patients and healthy individuals of Mongolian descent (P<0.05), as well as that of FHIT (68%, 30.67%) and CDH13 (64%, 26%) between liver cancer patients and healthy individuals of Han individuals (P<0.05). There was also a relationship between smoking and drinking and the methylation of FHIT and CDH13 (P<0.05). Thus, the methylation of FHIT and CDH13 had a relationship with liver cancer incidence. Smoking and alcohol ingestion may promote the methylation of FHIT and CDH13.

FHIT promoter DNA methylation and expression analysis in childhood acute lymphoblastic leukemia.

Fragile histidine triad (FHIT) is a tumor suppressor gene, which is involved in several malignancies. Epigenetic alterations in FHIT have been hypothesized to contribute to tumorigenesis. The present study aimed to examine DNA promoter methylation and gene expression levels of FHIT in childhood acute lymphoblastic leukemia (ALL), in a sample of Iranian patients. The promoter methylation status of FHIT was analyzed in 100 patients diagnosed with ALL and 120 healthy control patients. mRNA expression levels were assessed in 30 new cases of ALL compared with 32 healthy controls. Hypermethylation of the FHIT promoter was significantly more frequent in patients with ALL than in healthy controls (OR=3.83, 95% CI=1.51-9.75, P=0.007). Furthermore, FHIT mRNA expression levels were significantly reduced in childhood ALL patients compared with healthy controls (P=0.032). The results of the present study revealed that dysregulation of the FHIT gene may contribute to the pathogenesis of childhood ALL. Future studies investigating a larger sample population with greater ethnic diversity would be beneficial, to confirm the results from the present study.

Establishment of two data mining models of lung cancer screening based on three gene promoter methylations combined with telomere damage.

To identify the significance of a support vector machine (SVM) model and a decision tree (DT) model for the diagnosis of lung cancer combined with the detection of fragile histidine triad (FHIT), RAS association domain family 1 (RASSF1A) and cyclin-dependent kinase inhibitor 2A (p16) promoter methylation levels and relative telomere length (RTL) of white blood cells from peripheral blood DNA. The levels of p16, RASSF1A and FHIT promoter methylation and the RTL of white blood cells in peripheral blood DNA of 200 healthy individuals and 200 lung cancer patients were analyzed by SYBR Green-based quantitative methylation-specific PCR and quantitative PCR. Based on the 4 biomarkers, SVM and DT models were developed. The levels of FHIT, RASSF1A and p16 promoter methylation were 3.33 (1.86-6.40) and 2.85 (1.39-5.44) (p = 0.002); 27.62 (9.09-52.86) and 17.17 (3.86-50.87) (p = 0.038); and 0.59 (0.16-4.50) and 0.36 (0.06-4.00) (p = 0.008) in cases and controls, respectively. RTL was 0.93 ± 0.32 and 1.16 ± 0.57 (p<0.001). The areas under the receiver operating characteristic (ROC) curves of the Fisher discriminant analysis, SVM and DT models were 0.670 (0.569-0.761), 0.810 (0.719-0.882) and 0.810 (0.719-0.882), respectively. The SVM and DT models for diagnosing lung cancer were successfully developed through the combined detection of p16, RASSF1A and FHIT promoter methylation and RTL, which provided useful tools for screening lung cancer.

The potential of clofarabine in MLL-rearranged infant acute lymphoblastic leukaemia

MLL-rearranged acute lymphoblastic leukaemia (ALL) in infants is the most difficult-to-treat type of childhood ALL, displaying a chemotherapy-resistant phenotype, and unique histone modifications, gene expression signatures and DNA methylation patterns. MLL-rearranged infant ALL responds remarkably well to nucleoside analogue drugs in vitro, such as cytarabine and cladribine, and to the demethylating agents decitabine and zebularine as measured by cytotoxicity assays. These observations led to the inclusion of cytarabine into the treatment regimens currently used for infants with ALL. However, survival chances for infants with MLL-rearranged ALL do still not exceed 30–40%.Here we explored the in vitro potential of the novel nucleoside analogue clofarabine for MLL-rearranged infant ALL. Therefore we used both cell line models as well as primary patient cells. Compared with other nucleoside analogues, clofarabine effectively targeted primary MLL-rearranged infant ALL cells at the lowest concentrations, with median LC50 values of ∼25nM. Interestingly, clofarabine displayed synergistic cytotoxic effects in combination with cytarabine. Furthermore, at concentrations of 5–10nM clofarabine induced demethylation of the promoter region of the tumour suppressor gene FHIT (Fragile Histidine Triad), a gene typically hypermethylated in MLL-rearranged ALL. Demethylation of the FHIT promoter region was accompanied by subtle re-expression of this gene both at the mRNA and protein level. We conclude that clofarabine is an interesting candidate for further studies in MLL-rearranged ALL in infants.

Gene expression of WWOX, FHIT and p73 in acute lymphoblastic leukemia

The aim of the present study was to analyze the expression of WW-domain oxidoreductase (WWOX), fragile histidine triad (FHIT) and p73 in acute lymphoblastic leukemia (ALL). Samples from 122 ALL patients and 35 non-ALL control patients were collected in this study. RT-PCR was performed to detect the mRNA expression of WWOX, FHIT and p73. The methylation status of the WWOX promoter region, FHIT promoter region and the first exon region of p73 were also analyzed using the methylation-specific PCR method. The mRNA expression of WWOX, FHIT and p73 was significantly lower in the ALL samples compared with the controls (48.2, 42.9 and 55.4%, respectively). By contrast, the methylation frequency of WWOX, FHIT and p73 was significantly higher in the ALL samples compared with the controls (44.6, 46.4 and 37.5%, respectively). The mRNA expression of these three genes was inversely correlated with the methylation frequency in the ALL samples (correlation coefficients, −0.661, −0.685 and −0.536 for WWOX, FHIT and p73, respectively). Moreover, the mRNA expression of WWOX was positively correlated with that of FHIT and p73 (correlation coefficients, 0.569 and 0.556, respectively). However, the methylation status of WWOX had no correlation with that of FHIT or p73. It was concluded that the high methylation status of WWOX, FHIT and p73 may lead to the inactivation of expression and the silencing of these genes, promoting the occurrence and development of ALL. The determination of the mRNA expression and methylation status of WWOX, FHIT and p73 may aid in the development of treatment approaches for ALL.

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

BackgroundSarcoids are peculiar equine benign tumours. Their onset is associated with Bovine Papillomavirus type -1 or -2 (BPV-1/2) infection. Little is known about the molecular interplay between viral infection and neoplastic transformation. The data regarding papillomavirus infections in human species show the inactivation of a number of tumour suppressor genes as basic mechanism of transformation. In this study the putative role of the tumour suppressor gene Fragile Histidine Triad (FHIT) in sarcoid tumour was investigated in different experimental models. The expression of the oncosuppressor protein was assessed in normal and sarcoid cells and tissue.ResultsNine paraffin embedded sarcoids and sarcoid derived cell lines were analysed for the expression of FHIT protein by immunohistochemistry, immunofluorescence techniques and western blotting. These analyses revealed the absence of signal in seven out of nine sarcoids. The two sarcoid derived cell lines too showed a reduced signal of the protein. To investigate the causes of the altered protein expression, the samples were analysed for the DNA methylation profile of the CpG island associated with the FHIT promoter. The analysis of the 32 CpGs encompassing the region of interest showed no significative differential methylation profile between pathological tissues and cell lines and their normal counterparts.ConclusionThis study represent a further evidence of the role of a tumour suppressor gene in equine sarcoids and approaches the epigenetic regulation in this well known equine neoplasm. The data obtained in sarcoid tissues and sarcoid derived cell lines suggest that also in horse, as in humans, there is a possible involvement of the tumour suppressor FHIT gene in BPV induced tumours. DNA methylation seems not to be involved in the gene expression alteration. Further studies are needed to understand the basic molecular mechanisms involved in reduced FHIT expression.

Mutational and promoter hypermethylation status of FHIT gene in breast cancer patients of Kashmir

Objective Fragile histidine triad ( FHIT) gene located at chromosome 3p14.2 is a putative tumor suppressor gene involved in the pathogenesis of breast cancer. Both genetic and epigenetic alterations in FHIT have been implicated in breast carcinoma. In the present study, our main aim was to study the impact of these two kinds of alterations of FHIT gene in breast cancer patients of Kashmir. Methods We screened a total of 130 breast cancer patients of Kashmir by PCR-SSCP followed by direct sequencing and methylation specific PCR. Results Mutational screening of FHIT gene revealed significant amount of mutations [40.7% (53/130)] in five hot spot exons (exon 5–9), FHIT promoter was found to be hypermethylated in 59 of 130 [45.3%] breast cancer patients in our population. Conclusion In the present study we have shown a significant association between the mutational and hypermethylation profile of FHIT gene. Hence, we provide the first evidence to our knowledge that the significant association of FHIT mutation and hypermethylation leads to the complete inactivation of FHIT gene in patients with breast cancer. Silencing of the FHIT gene by promoter hypermethylation occurs in breast carcinomas, especially those with the significant amount of mutations.

Effects of Methylation of FHIT Gene on it's Protein and mRNA Expression in Non-small Cell Lung Cancer.

Fragile histidine triad (FHIT) is a new tumor suppressor gene, whose promoter methylation plays an important role in carcinogenesis. The aim of this study is to explore the effects of CpG island methylation on protein and mRNA expression of FHIT in non-small cell lung cancer, and the roles of FHIT gene in pathogenesis of NSCLC. Methylation and protein expression and transcriptional level of FHIT gene were detected by methylationspecific PCR, Western Blot and RT-PCR in 52 tumor tissues and normal tissues of NSCLC. Methylation in the tumor samples was detected at 38.46%, whereas it occurred at lower frequencies (7.69%) in the corresponding normal lung tissues. Protein expression frequencies was 28.8% in the tumor samples, whereas it was 88.5% in the corresponding normal lung tissues. MRNA expression frequencies was 51.9% in the tumor samples and 100% in the corresponding normal lung tissues. In NSCLC, FHIT gene promoter methylation frequency was significantly increased with decreased expression, suggesting that FHIT promoter methylation plays a role in lung cancer carcinogenesis.

Fragile Histidine Triad Gene Inactivation in Lung Cancer

Fragile histidine triad (FHIT) is a tumor suppressor gene involved in the pathogenesis of lung cancer. The purpose of this study was to investigate the different molecular alterations leading to the inactivation of FHIT gene function and to validate their use as biomarkers of risk for progression of the disease in patients belonging to the multicentric European study for the Early detection of Lung Cancer (EUELC) who were resected for early-stage lung tumors. FHIT immunostaining was performed on 305 tumor samples. The methylation status of FHIT promoter was assessed by nested methylation-specific polymerase chain reaction (MSP-PCR) in 232 tumor and 225 normal lung samples of which a subset of 187 patients had available normal/tumor DNA pairs. Loss of heterozygosity (LOH) at the FHIT locus was analyzed in 202 informative cases by D3S1300 and D3S1234 microsatellite markers. Lost or reduced FHIT expression was found in 36.7 and 75.7% of the tumor samples, respectively. Methylation of the FHIT promoter was found in 36.7% of tumor and 32.7% of normal lung samples, whereas LOH was detected in 61.9% of the tumors. A strong association with complete loss of FHIT expression was present when methylation and LOH were analyzed together (P = 0.0064). Loss of FHIT protein expression was significantly more frequent in squamous cell carcinoma histotype (P < 0.0001) and in smokers (P = 0.008). FHIT methylation in normal lung was associated with an increased risk of progressive disease (OR, 2.27; P = 0.0415). Our results indicate that different molecular mechanisms interplay to inactivate FHIT expression and support the proposition that FHIT methylation in normal lung tissue could represent a prognostic marker for progressive disease.

Role of 5'-CpG island hypermethylation of the FHIT gene in cervical carcinoma

The abnormal expression of fragile histidine triad (FHIT) gene has been frequently reported in a variety of epithelial malignancies including cervical carcinoma. Furthermore, in a recent study it was proposed that transcriptional inactivation of FHIT, as a consequence of aberrant 5'-CpG island methylation, plays an important role in the carcinogenesis of human cervical carcinoma. The authors sought to determine whether abnormal FHIT transcription occurs in human cervical carcinoma, and if so, whether this abnormal expression is associated with aberrant 5'-CpG island methylation. In addition, the clinical significance of FHIT inactivation was investigated in Korean women with cervical cancer. To examine for abnormal transcripts of the FHIT gene, quantitative RT-PCR, genomic DNA-PCR and nonisotopic RT-PCR-SSCP analysis were performed using the standard method. The methylation status was determined by methylation specific PCR and bisulfite DNA sequencing. The FHIT gene was down-regulated in 15 of 58 (25.9%) cervical carcinomas. FHIT promoter hypermethylation was detected in 15 of 15 (100%) abnormally expression in cervical carcinomas. Bisulfite DNA sequencing confirmed these findings and a significant correlation was found between CpG site hypermethylation and low FHIT expression. However, no significant correlation was found between reduced FHIT expression and clinicopathological characteristics. In this study, FHIT inactivation in cervical cancer was found to be strongly correlated with 5'-CpG island hypermethylation rather than a genetic alteration. Furthermore, no significant relation was found between a lack of FHIT expression and the prognostic factors of cervical cancer in our Korean cohort.

Epigenetic silencing contributes to frequent loss of the fragile histidine triad tumour suppressor in basal cell carcinomas

Extensive exposure to ultraviolet radiation is associated with genetic alterations in basal cell carcinomas (BCCs), which represent some 75% of skin cancers. As recent data suggested the fragile histidine triad (FHIT) gene product to participate in DNA damage responses we wished to address whether functional deletion of this tumour suppressor participates in the development of BCC. Our study focused on epigenetic inactivation of the FHIT gene. Paraffin-embedded specimens from 17 patients with BCC were available for methylation-specific polymerase chain reaction (MSP), combined bisulphite-dependent restriction analysis (COBRA) of the FHIT gene and immunohistochemistry of its product. We report for the first time that 100% of BCCs are negative for FHIT by immunostaining. Aberrant methylation of the FHIT promoter occurred in a significant portion of BCCs. MSP detected hypermethylation of the FHIT/FRA3B locus in nine of nine (100%) periocular BCCs and in six of eight (75%) BCCs from other body regions. COBRA yielded similar results, confirming that some 88% of the 17 BCCs analysed harbour epigenetic silencing of the FHIT gene. Loss of FHIT protein was demonstrated immunohistochemically, confirming that promoter hypermethylation correlated with loss of gene expression. We have identified epigenetic silencing of the FHIT tumour suppressor gene as a frequent inactivation mechanism which is likely to contribute to functional deficiencies in DNA damage response of BCCs.

Aberrant methylation of Fragile Histidine Triad gene is associated with poor prognosis in early stage esophageal squamous cell carcinoma

The aim of this study was to understand the clinicopathological and prognostic significance of promoter methylation of Fragile Histidine Triad ( FHIT) gene in esophageal cancer. FHIT methylation in 257 primary esophageal squamous cell carcinomas was retrospectively analyzed by methylation-specific polymerase chain reaction. Aberrant methylation of FHIT was found in 85 (33%) of 257 esophageal cancer patients. The FHIT methylation was found to be significantly associated with exposure to tobacco smoke ( P = 0.007) and with a poor prognosis in cases of stage 1–2 cancer irrespective of recurrence. The hazard of failure after esophagectomy for stage 1–2 cancers with FHIT methylation was about 5.81 (95% CI = 1.15–14.07; P = 0.009) times higher than in those without. Recurrence occurred in 116 (45%) of the 257 patients studied. The survival after recurrence in stage 1–2 cancers was also poorer for patients with FHIT methylation than in those without (HR = 2.31; 95% CI = 1.18–7.92; P = 0.03). In conclusion, aberrant methylation of the FHIT promoter was found to be significantly associated with exposure to tobacco smoke and with a poor prognosis for stage 1–2 cases, but not with recurrence rate. Our study suggests that FHIT promoter methylation may be an independent prognostic biomarker in early stage esophageal squamous cell carcinoma.

Loss of Fragile Histidine Triad Gene Expression in Advanced Lung Cancer Is Consequent to Allelic Loss at 3p14 Locus and Promoter Methylation

The fragile histidine triad (FHIT) gene located at the 3p14.2 locus plays an important role in the pathogenesis of lung cancer. The objective of this study was to analyze loss of heterozygosity and FHIT gene methylation status and correlate them to fhit expression. Bronchoscopically obtained lung biopsies from 30 cases of histologically proven carcinoma of the lung in stage III were assessed for the alterations in the FHIT gene. Fhit protein expression was determined by immunohistochemistry, and transcript levels were determined by reverse transcription-PCR. Microsattelite alterations and methylation status of the Fhit gene promoter was determined by PCR. Loss of heterozygosity at the 3p14 locus was observed in all the 30 cases at least by one of the three microsatellite polymorphic markers. The FHIT gene promoter showed complete methylation in 37% cases and partial methylation in 47% cases, and 16% cases showed no promoter methylation. FHIT full-length coding region (exons 5-9) transcripts were present in eight cases (26.6%), and aberrant transcripts were additionally seen in four cases. Loss of FHIT mRNA expression correlated to FHIT promoter methylation but not to loss of heterozygosity at the 3p14 locus. There was a strong correlation between the expression of FHIT at the transcript and protein level. The apoptotic index estimated by the terminal deoxynucleotidyl transferase-mediated nick end labeling assay was significantly correlated to the fhit protein expression. The results of this study indicate that in locally advanced carcinoma of the lung, there is frequent loss of FHIT expression, and methylation of the FHIT gene promoter is an important mechanism of its inactivation.

Promoter methylation and loss of coding exons of the fragile histidine triad (FHIT) gene in intrahepatic cholangiocarcinomas

About 10-30% of primary liver cancers represent intrahepatic cholangiocarcinomas (IHCC). Since chromosomal losses of 3p are detectable in about 40% of cholangiocarcinomas our study aimed at the identification of mechanisms leading to functional deletion of tumor suppressor genes in this region. Our efforts focussed on genomic losses and epigenetic inactivation of two tumor suppressor genes, the fragile histidine triad (FHIT) and the ras association domain family 1 (RASSF1A) genes, both located on the short arm of chromosome 3. Methylation-specific PCR (MSP) and combined bisulfite-dependent restriction analysis (COBRA) were applied to detect epigenetic silencing of gene promoters. Genomic duplex PCR was used to identify exon losses of the FHIT gene. Nineteen paraffin-embedded samples of intrahepatic cholangiocarcinomas were studied. Here we report for the first time that in addition to frequent losses of the exons 5 and 6, hypermethylation of the FHIT promoter occured in a significant portion of IHCC. Methylation specific PCR (MSP) detected epigenetic inactivation of the FHIT/FRA3B locus in 8 of 19 (42%) cases. Combined bisulfite restriction analysis (COBRA) revealed that high levels of methylated FHIT promoter sequences were present in 6 of the 8 methylation positive samples. In agreement with previous reports MSP identified hypermethylation of the RASSF1A gene in 13 of 19 (68%) IHCC specimens examined. Epigenetic silencing of the FHIT tumor suppressor gene is a novel inactivation mechanism to be considered in the development of intrahepatic cholangiocarcinomas. However, a statistically significant inverse correlation between K-Ras activation and RASSF1A inactivation was not found.

Hypermethylation of fragile histidine triad gene and 3p14 allelic deletion in ovarian carcinomas

The FHIT (fragile histidine triad) is a candidate tumor suppressor gene (TSG) located on chromosome 3p14.2. Hypermethylation and loss of heterozygosity (LOH) are major mechanisms in the inactivation of tumor suppressor genes. In this study, the methylation status of FHIT and LOH of 3p14 in 61 cases of human sporadic ovary carcinomas were investigated. Sixty-one primary ovary carcinomas and 10 borderline ovarian tumors were analyzed with methylation specific PCR (MSP) to detect the CpG island methylation status in the FHIT promoter region. In addition, 45 cases of ovary carcinomas and their corresponding non-tumor ovary tissues were investigated with D3S1287 microsatellite polymorphic marker for LOH. Hypermethylation of FHIT gene was observed in 39.3% (24/61) of ovarian carcinomas. The frequencies of hypermethylation in serous ovarian carcinoma, mucinous ovarian carcinoma, endometrioid ovarian carcinoma and ovary borderline tumor were 45.2% (19/42), 14.3% (1/7), 33.3% (4/12) and 60.0% (6/10), respectively. Ten of twenty-three (43.5%) informative tumors showed LOH and 6 of 18 (33.3%) informative cases showed homozygous deletions. The status of FHIT methylation was not associated with clinical stage and differentiation grade, there was no significant difference between the malignant and borderline tumors. Hypermethylation and allelic deletion of FHIT are frequent events in ovarian carcinomas and are important mechanisms for the loss of expression of this gene.

Fragile genes as biomarkers: epigenetic control of WWOX and FHIT in lung, breast and bladder cancer

This study aimed to (a) determine if DNA methylation is a mechanism of WWOX (WW domain containing oxidoreductase) and FHIT (fragile histidine triad) inactivation in lung, breast and bladder cancers; (b) examine distinct methylation patterns in neoplastic and adjacent tissues and (c) seek correlation of methylation patterns with disease status. Protein expression was detected by immunohistochemistry, and methylation status by methylation-specific PCR (MSP) and sequencing, in lung squamous cell carcinomas and adjacent tissues, invasive breast carcinomas, adjacent tissues and normal mammary tissues and bladder transitional cell carcinomas. Wwox and Fhit expression was reduced in cancers in association with hypermethylation. Differential patterns of WWOX and FHIT methylation were observed in neoplastic vs adjacent non-neoplastic tissues, suggesting that targeted MSP amplification could be useful in following treatment or prevention protocols. WWOX promoter MSP differentiates DNA of lung cancer from DNA of adjacent lung tissue. WWOX and FHIT promoter methylation is detected in tissue adjacent to breast cancer and WWOX exon 1 MSP distinguishes breast cancer DNA from DNA of adjacent and normal tissue. Differential methylation in cancerous vs adjacent tissues suggests that WWOX and FHIT hypermethylation analyses could enrich a panel of DNA methylation markers.

MLL Rearranged Infant Acute Lymphoblastic Leukemia Is Characterized by Silencing of the Putative Tumor Suppressor Gene FHIT.

MLL gene rearranged acute lymphoblastic leukemia (MLL) is an aggressive type of acute lymphoblastic leukemia (ALL) with a relatively poor response to treatment, predominantly occurring in infants (<1 years of age). Since conventional chemotherapy is failing in >50% of these patients, identification of novel therapeutic targets to direct therapy against is demanded. For this, understanding this disease and finding biological and molecular features characterizing MLL may be crucial. Here we report that infant MLL is characterized by silencing of the putative tumor suppressor fragile histidine triad (FHIT) gene.Gene expression profiling showed that FHIT expression is significantly reduced in MLL patients (n=20) as compared to patients diagnosed with conventional ALL (n=24) bearing germ line MLL genes. Using quantitative real-time PCR we confirmed FHIT mRNA expression to be low in MLL gene rearranged infant ALL (infant MLL) as compared to both infants and older children (non-infants) not carrying chromosomal abnormalities involving the MLL gene. Infant MLL patients (n=35) significantly (p<0.001) expressed ~15-fold less FHIT mRNA compared to infant ALL patients (n=8) and 11-fold less than non-infant ALL patients (n=22).Methylation specific PCR (MSP) analysis demonstrated that the FHIT promoter region is hypermethylated in all of the 36 infant MLL cases tested, resulting in strongly reduced FHIT mRNA as well as FHIT protein expression. In contrast, the incidence of FHIT promoter methylation in both infant and non-infant ALL patients carrying germ line MLL genes was markedly lower, with a frequency of 63% (5/8) and 56% (24/43) respectively. Suppression of FHIT expression could be reversed by exposing leukemia cells bearing MLL gene rearrangements to the demethylating drug 5′-aza-2′-deoxycytidine.These findings imply that MLL rearranged ALL is characterized by FHIT promoter hypermethylation. Currently experiments are being conducted to determine the biological significance of FHIT silencing in this type of cancer.

FHIT expression and hypermethylation in esophageal squamous cell carcinoma

The expression of the fragile histidine triad (FHIT) gene has been proposed to play an important role in early events of carcinogenesis and to be correlated with the progression or clinical outcomes of various cancers. Attention has focused recently on the regulation of FHIT expression, and loss of heterozygosity or hypermethylation of the CpG island in the promoter region has been suggested as clues to a possible mechanism. Methylation status and FHIT expression were investigated in the present study to clarify the clinicopathologic impact of FHIT in vivo. One hundred and five patients with esophageal cancer were admitted to the study. Cancer tissues were immunohistochemically stained for FHIT, and FHIT methylation status was examined in 36 patients by the methylation-specific polymerase chain reaction. FHIT methylation and expression were analyzed with respect to both clinicopathologic parameters and their interactions. Tissue specimens from 35 of the 105 patients (33.3%) stained positively for FHIT. In contrast, the CpG island in the FHIT promoter region was hypermethylated in 25 of the 36 (69.4%) analyzed cases of esophageal cancer. Hypermethylation was significantly correlated with the deletion of FHIT protein expression (P<0.001). FHIT hypermethylation was not associated with any clinicopathologic parameters. In contrast, deletion of FHIT expression significantly promoted tumor invasion (P<0.05) and lymphatic vessel invasion (P<0.01). Lymph node metastasis also appeared higher in the absence of FHIT protein expression, but the result was not significant (P=0.069). Patients with a preserved FHIT gene expression possibly exhibited an improved prognosis compared with those with deleted FHIT expression (P=0.093). Hypermethylation of the FHIT promoter region may be a mechanism for regulating FHIT expression. FHIT gene expression was closely correlated with cancer progression, as indicated by tumor invasion and lymphatic spread, and it may provide insight into the mechanism of progression of esophageal cancer.