Aberrant Fragile Histidine Triad Research Articles

Protein expression of Fragile Histidine Triad and cyclooxgenase-2 in serrated neoplasia of the colorectum.

The adenoma-carcinoma sequence (ACS) and the serrated pathway are two distinct developmental routes leading to the formation of colorectal carcinoma (CRC). However, the mechanism triggered by the serrated pathway remains unclear. Therefore, to clarify the molecular and clinicopathological characteristics of the serrated tumorigenic pathway, immunohistochemistry was used to examine the expression of Fragile Histidine Triad (FHIT), cyclooxygenase-2 (COX-2), MutL homolog 1 (MLH1), MutS protein homolog 2 (MSH2) and P53 in endoscopically resected samples of 62 serrated polyps. These samples included 20 hyperplastic polyps (HPs), 16 traditional serrated adenomas (TSAs), 26 sessile serrated adenoma/polyps (SSA/Ps), 20 non-serrated adenomas, 20 carcinoma in adenomas (CIAs) and 18 early pure CRCs without any adenoma component (EPCs). FHIT expression was markedly reduced or absent in 50% of TSA samples, 92.3% of SSA/Ps and 44% of EPCs, but only rarely in HPs, non-serrated adenomas and CIAs. COX-2 expression was more common in non-serrated adenomas compared with in serrated polyps, and was present in 25 and 3.2% of the cases respectively (P<0.01). Furthermore, COX-2 expression was more frequent in CIAs (60%) compared with in EPCs (22.2%; P<0.05). The incidence of negative COX-2 expression was higher in FHIT-negative SSA/Ps compared with in FHIT-positive SSA/Ps (P=0.08). A total of 16.7% of EPC samples and 11.5% of SSA/Ps demonstrated a loss of MLH1/MSH2 expression, but none of the other tumor types did. P53 overexpression was significantly increased in EPC (77.8%) and CIA (60%) samples compared with in HP (0%), TSA (6.6%), SSA/P (0%) and non-serrated adenoma (10%) samples (P<0.01). These findings demonstrated that there are different expression patterns between the serrated pathway and ACS, indicating that aberrant FHIT and inhibited COX-2 expression may be associated with serrated tumorigenesis. In addition, this data indicated that EPC may contain tumors derived from the serrated pathway as well as ACS.

Molecular Cloning of the Canine Fragile Histidine Triad (FHIT) Gene and Fhit Protein Expression in Canine Peripheral Blood Mononuclear Cells

A fragile histidine triad (FHIT) gene has been studied as a tumor-associated gene in humans. The aberrant FHIT gene and its protein expression have been reported in many types of human cancers. The present study explored the canine FHIT gene structure and its protein expression in the peripheral blood mononuclear cells of healthy dogs by RT-PCR, RACE and immunoblot analysis. The obtained canine FHIT gene contained nine small exons and was located on canine chromosome 20. Furthermore, we identified an alternative splicing form of the FHIT transcript. The deduced amino acid sequence was well conserved between species, and anti-human Fhit antibody could be used to detect the canine Fhit protein. These findings will be useful for future research.

Aberrations of the FHIT Gene and Fhit Protein in Canine Lymphoma Cell Lines

The fragile histidine triad (FHIT) gene is a tumor-associated gene, and aberrant FHIT gene and protein expression have been described in many types of human tumors. Furthermore, it has been reported that FHIT gene inactivation is induced by hypermethylation of 5' CpG islands in the gene or by genomic deletion around the open reading frame (ORF). In this study, we explored the aberrations in the canine FHIT gene and Fhit protein expression and assessed the methylation status and genomic deletions by using 5 canine lymphoma cell lines. We found that the decrease in the expression of the Fhit protein in canine lymphoma cell lines was similar to that in human tumors. The expression of the wild-type FHIT transcript was reduced in all 5 cell lines. However, we could not confirm the involvement of aberrant methylation events in the 5' CpG islands of the canine FHIT gene. We were able to identify homozygous or heterozygous deletions in the canine FHIT genes in all 5 cell lines. Moreover, a widespread genomic deletion of the FHIT gene, which included the ORF region, was detected in 1 cell line. In the present study, we detected aberrations in the FHIT gene and Fhit protein expression in all 5 canine lymphoma cell lines, and this phenomenon might be an important factor in promoting canine lymphoma.

Decreased fragile histidine triad expression in colorectal cancer and its association with apoptosis inhibition

To detect the expression of fragile histidine triad (FHIT) in normal colorectal tissue, colorectal adenoma and colorectal cancer (CRC) tissue, and to analyze its relationship with the clinicopathological features of CRC, and apoptosis-associated proteins (Bcl-2, Bax, survivin) and apoptosis in colorectal cancer. FHIT mRNA analysis was performed by nested reverse transcription-polymerase chain reaction (RT-PCR) assay. Tissue microarray (TMA) was established to detect the expression of FHIT, Bcl-2, Bax and survivin genes in 80 CRC tissue specimens, 16 colorectal adenoma tissue specimens and 16 hemorrhoid (PPH) tissue specimens during the same period of time as the control. Citrate-microwave-SP was used as immunohistochemical method. The relationship between clinicopathological factors, such as differentiation grades and 5-year survival rate was observed. TUNEL assay was used to detect the apoptosis index in 80 CRC tissue specimens. Ten out of 26 (38.5%) CRC tissue specimens expressed aberrant FHIT transcripts, none of the aberrant FHIT transcripts was observed in the matched normal tissue and colorectal adenoma tissue by nested RT-PCR assay. The positive rate of FHIT gene expression in normal colorectal tissue, colorectal adenoma and carcinoma tissue was 93.75%, 68.75% and 46.25%, respectively. Clinicopathological analysis of patients showed that the decreased FHIT gene expression was not associated with age, sex, serum CEA levels, tumor site and size, histological classification. However, the expression of FHIT was correlated with differentiation grades, pathological stages, lymph node metastases and 5-year survival rate after operation. The positive rate of apoptosis-associated proteins (Bax, Bcl-2 and survivin) in CRC tissue was 72.50%, 51.25% and 77.50%, respectively. The expression of these apoptosis-associated proteins in CRC tissue was correlated with the expression of FHIT. The mean apoptosis index in FHIT negative tumors was significantly lower than that in FHIT positive tumors (5.41 +/- 0.23 vs 0.56 +/- 0.10, P < 0.01). The FHIT gene plays an important role in the regulation of apoptosis and decreased FHIT expression plays a key role in the initiation and progression of colorectal carcinoma.

Aberrant FHIT protein expression in classical Hodgkin’s lymphoma: a potential marker

The fragile histidine triad (FHIT) gene is frequently inactivated in human cancers; however, the FHIT gene remains unexplored in Hodgkin's lymphoma. The aim of this study was to investigate the role of FHIT expression in classical Hodgkin's lymphoma. Classical Hodgkin's lymphomas were analysed for FHIT gene expression by two-step non-biotin immunohistochemical method and Western blotting. Thirty of the 33 (91%) cases of Hodgkin's lymphoma tested were positive for FHIT protein by immuohistochemistry. The expression of FHIT was mainly located in cytoplasm of Reed-Sternberg (HRS) cells. The protein expression was also documented by Western blotting. The non-Hodgkin's lymphomas were negative for FHIT protein. The results indicate that abnormal FHIT expression is noted frequently in classical Hodgkin's lymphoma and the expression can give insight into the pathogenesis of the disease. The protein may serve as a marker to localise HRS cells in classical Hodgkin's lymphoma.

Molecular genetic alterations of FHIT and p53 genes in benign and malignant thyroid gland lesions

Several oncogenes and tumor-suppressor genes are involved either as early or late event in thyroid gland carcinogenesis. Human FHIT (fragile histidine triad) gene is highly conserved gene whose loss of function may be important in the development and/or progression of various types of cancer. We undertook this study to analyze FHIT and p53 gene status in different benignant and malignant thyroid tumors. Status of these genes as well as intensity of apoptosis was analyzed in tumor tissues by molecular genetic methods, immunohistochemistry, and FACS-scan analysis. The majority of the malignant thyroid cancers displayed aberrant expression of FHIT gene, concominant with p53 gene inactivation. This is followed by low rate of apoptosis, which may be important in the development and/or progression of thyroid cancer. We found higher incidence of p53 mutation and aberrant processing of FHIT mRNA in malignant tumors (papillary, follicular, medullary and anaplastic carcinomas) and in those tumors with distant metastasis. The growth of p53 −/ FHIT − follicular carcinoma of human origin was much faster in nude mice than p53 + / FHIT + follicular carcinoma, and mice had shorter survival rate. Our results show a correlation between aberrant FHIT and p53 expression, low rate of apoptosis, and malignancy. Concomitant aberration of FHIT gene and p53 could be responsible for development of highly malignant types of thyroid cancer and may be considered as a prognostic marker for these tumors.

Alterations of the fragile histidine triad gene in hepatitis C virus‐associated hepatocellular carcinoma

The present study was conducted to address whether homozygous deletion (HZD) or transcriptional alterations of the fragile histidine triad (FHIT) gene play a role in the development and progression of hepatitis C virus-associated hepatocellular carcinoma (HCC). Homozygous deletion of the FHIT gene at exons 3-9 was assessed as well as mRNA FHIT expression using reverse transcription polymerase chain reaction. The study included 23 samples of HCC, 11 on top of cirrhosis and 12 non-cirrhotic, in addition to five cases with chronic active hepatitis (CAH), as well as seven morphologically normal tissues distant to the tumor (NDT) and 10 normal liver samples from liver transplantation donors. Homozygous deletion was found in 18 of 23 HCC cases. The highest incidence of deletion was detected in exon 9 (52.0%) and the lowest in exon 7 (4.3%). Ten of the 18 cases (55.5%) showed deletion in more than one exon, eight in two exons, one in three exons and one in five exons. There was a significant association between HZD of exons 5 and 9 and HCC arising on top of cirrhosis (P = 0.041 and 0.006, respectively) as well as between exons 8 and 9 and the presence of CAH (P = 0.029 and 0.034, respectively). Aberrant FHIT transcripts were detected in 15 HCC cases (65.2%), 13 of them showed complete reduction of the mRNA transcripts and two showed abnormal bands. Sequence analysis of abnormal-sized transcripts revealed that they were generated by the fusion of exons 5 and 7 as well as exons 7 and 9. In contrast, six of the seven NDT samples tested (85.6%) showed HZD in one or more exons. None of the normal liver samples from liver transplantation donors showed any changes. The highest incidence of HZD was detected in exon 9 (five of six cases representing 83.3%) and the lowest was in exon 4 (one of six cases representing 16.7%). Four cases showed the same aberrant FHIT HZD in both NDT and matched HCC. The results of the present study indicate that the FHIT gene is a frequent target in hepatitis C virus-associated HCC and that alterations affecting this gene could be an early event in this type of neoplasm as they were detected in cirrhotic and CAH patients. However, this should be confirmed by a larger, extended study including more cases of cirrhotic and CAH patients as well as matched tumor and normal samples.

Abnormal Fragile Histidine Triad Gene Expression in Gastric Cancer

Purpose: Genomic alterations and abnormal expression of the fragile histidine triad (FHIT) gene in gastric cancer were examined to determine whether the FHIT gene is actually a frequent target for alteration during gastric carcinogenesis. Materials and Methods: To correlate DNA and RNA lesions of the FHIT gene with the effect on FHIT protein expression, in 40 gastric cancers, we investigated the FHIT gene for loss of heterozygisity (LOH), aberrant transcripts, and protein expression. Results: Allelic loss at D3S1300 was detected in 7 of 38 () informative cases. Aberrant transcripts were observed in 20 of 40 () cases. Significant reduction of FHIT protein expression was observed in 22 of 40 () cases. Aberrant FHIT transcription was shown to be associated with loss of FHIT protein expression. However, aberrent FHIT transcripts themselves were not associated with any clinicopathological parameters, such as age, sex, tumor site, or clinical stage. Moreover, there was no association between the presence of LOH at D3S1300 and the expression of aberrant FHIT transcripts. Conclusion: The high frequency of aberrant FHIT transcripts, the significant rate of LOH at D3S1300, and the altered expression of the FHIT protein indicate that alterations of the FHIT gene can play an important role in gastric carcinogenesis.

Multiple molecular alterations of FHIT in betel-associated oral carcinoma.

To determine the alterations of the FHIT (fragile histidine triad) gene in oral squamous cell carcinoma (OSCC), this study examined mutation, promoter methylation, mRNA transcription, and protein expression of FHIT in OSCC associated mostly with the use of betel and/or tobacco. Analyses of the coding exons (exons 5-9) identified a deletion of one base in intron 4 in one tumour and a deletion of exon 7 in two tumours. Using bisulphite genomic sequencing, 28% of the informative subjects exhibited promoter methylation. An aberrant FHIT transcript spanning from exon 3 to exon 10, which was verified by RT-PCR analysis, was identified in 36% of the OSCC subjects, 50% of the oral pre-invasive lesions, and 5% of the non-cancerous match tissue. An abnormal immunohistochemical level of Fhit was detected in 41% of OSCC subjects. A statistically significant association was found between aberrant transcription of the FHIT gene and an abnormal level of Fhit immunoreactivity. The results indicated that alteration of FHIT is a frequent occurrence in OSCC and thus suggests that the aberrance in FHIT transcription could be an early event of oral carcinogenesis.

Characterization of aberrant FHIT transcripts in gastric adenocarcinomas.

Aberrant transcripts of FHIT (fragile histidine triad) have been reported in several types of primary tumors and cell lines, including gastric carcinoma. The role of these aberrant transcripts in tumorigenesis is not clear yet. Forty-eight aberrant-sized FHIT transcripts with various lengths and number in 35 cases of gastric adenocarcinomas were further characterized. Aberrant transcripts, with deletions and/or insertions, were frequently observed in 20 cases of tumors. Sequence analysis demonstrated that different types of aberrant transcripts used normal splice sites but skipped exons, contained the inserts with the part of intron 5 sequences, or used the FHIT cDNA sequence 179-180 as a cryptic splice acceptor site. Most of aberrant transcripts lacked exon 5 and were presumably non-functional as the translation initiation codon is located in exon 5. Additionally, other transcripts, indicative of additional splice processing, either deletions or insertions, were expressed in several tumors. Taken together, our data indicate that the FHIT gene expression is frequently altered in gastric adenocarcinomas by aberrant splicing, and suggest that different types of aberrant transcripts may result during the multi-step splice processing.

FHIT (Fragile Histidine Triad) Gene Analysis in Cervical Intraepithelial Neoplasia

Objective. Recently a candidate tumor suppressor gene, FHIT (fragile histidine triad), was identified at chromosome 3p14.2. Abnormality of this gene has been observed in a variety of human tumors. Although aberrant FHIT transcripts in a substantial percentage of cervical cancer cell lines and primary cervical tumors were also noted, some other studies revealed different results. Therefore, its association with the development of cervical cancer is still debatable. Because allelic loss in chromosome 3p is also a frequent finding in cervical intraepithelial neoplasia (CIN), we compared the transcription pattern and expression of FHIT in the preinvasive cervical lesions and normal cervical epithelia to investigate its possible role in cervical carcinogenesis.Methods. Thirty-five consecutive CIN lesions taken from conization specimens and 33 normal cervical epithelial tissues taken from hysterectomy for benign diseases were included in this study. Total RNA was extracted from the pathology-confirmed tissue samples and first-strand cDNA was synthesized. It was amplified using a nested reverse transcription polymerase chain reaction (RT-PCR) method. The PCR products were then subjected to subcloned sequence analysis. Paraffin blocks from all of the samples were selected and prepared for immunohistochemical study with an anti-FHIT polyclonal antibody.Results. All the cDNAs of CIN and normal cervical epithelial tissues showed the expected size of RT-PCR product. However, 7 of the 35 (20%) CIN lesions and 5 of the 33 (15%) normal cervical epithelia also presented aberrant transcripts in addition to the normal-sized transcript of FHIT. Deletion of the cDNA segment covering exon 4 to exon 8 was the most frequent finding in the cases that showed abnormal FHIT transcripts. FHIT protein was intermediately or strongly expressed in most of the CIN lesions and normal squamous epithelia. However, reduced or absent FHIT expression was observed heterogeneously in the 7 CIN lesions and 5 normal cervices in which aberrant FHIT transcripts were detected.Conclusion. Because the normal-sized FHIT transcript was present robustly in all of the CIN lesions and the abnormal FHIT transcripts occurred with similar frequency and pattern in the CIN lesions and normal cervical tissues, we suggest that abnormal FHIT transcription might not be causal in the early process of cervical carcinogenesis.

Aberration of FHIT Gene is Associated with Increased Tumor Proliferation and Decreased Apoptosis—Clinical Evidence in Lung and Head and Neck Carcinomas

Human FHIT (fragile histidine triad) gene is highly conserved gene homologous to a group of genes identified in prokaryotes and eukaryotes. Loss of FHIT function may be important in the development and/or progression of various types of cancer. We undertook a clinical study to analyze the relation between aberrant function of FHIT gene, tumor cell proliferation, and intensity of apoptosis as well as prognostic output in lung and squamous cell head and neck carcinoma (HNSCC). Status of FHIT gene, expression of p21waf1, intensity of apoptosis, and cell proliferation were analyzed in HNSCC and lung carcinoma tissues by molecular genetic methods, immunohistochemistry, [3H]-thymidine labeling method, and FACScan analysis in frozen and paraffin-embedded tissue sections. The majority of the malignant lung and HNSCC lesions displayed aberrant expression of FHIT gene, followed by low or negative expression of p21waf1, and increased intensity of cell proliferation. Similar results were obtained on synchronous combinations of normal, precancerous, and cancerous head and neck tissues. The observed changes increased with progression of these lesions. We examined tumor and corresponding normal tissue samples for microsatellite markers D3S1300 and D3S4103 to evaluate the loss of heterozygosity (LOH) at the FHIT gene loci. We found high percentage of LOH in both lung tumors and HNSCC (75% for D3S1300 and 79% for D3S4103 in lung cancer, and 87% for D3S1300 and 78% for D3S4103 in HNSCC). The median survival time of the patients suffering from lung cancer without FHIT protein expression was 22.46 months and that of the patients with FHIT expression 36.04 months. FHIT-negative cases tended to correlate with a worse prognosis, but this was not statistically significant. Median survival time of HNSCC patients without FHIT protein expression was 30.86 months and that of the patients with FHIT expression was 64.04 months (p < 0.05). Our results show a correlation between aberrant FHIT expression, a low rate of apoptosis, and high tumor cell proliferation. Aberrant FHIT gene could be a prognostic marker in lung cancer.

Impaired FHIT expression characterizes serous ovarian carcinoma.

The FHIT (fragile histidine triad) gene on chromosome 3p14.2 is a candidate tumour suppressor gene. To define the role of the FHIT gene in the development of ovarian cancer, we have examined 33 ovarian carcinomas, 2 borderline tumours and 10 benign adenomas for the presence of FHIT gene alterations. FHIT transcripts were analysed by RT-PCR and sequencing. Aberrant FHIT transcripts were observed in 5/33 carcinomas (15%) and in 1 of 2 borderline tumours. Loss of normal FHIT transcript was observed in 5/33 carcinomas (15%) but not in 2 borderline tumours or 10 benign adenomas. Allelic losses at D3S1300 and D3S4103, both located within intron 5 of FHIT were detected in 5/24 (21%) and 5/25 (20%) informative ovarian carcinomas, respectively. Expression of Fhit protein was analysed by immunohistochemistry in 44 carcinomas, 19 borderline tumours and 16 benign adenomas. Loss or significantly reduced expression of Fhit protein was observed in 6/44 (14%) ovarian carcinomas but not in any of 19 borderline tumours or 16 benign adenomas. The impaired Fhit protein expression was significantly correlated with the loss of normal FHIT transcription. Most notably, loss of normal FHIT transcript and impaired expression of Fhit protein occurred only in serous adenocarcinomas of grade 2 and 3 (5/15; 33% and 6/19; 32%, respectively). The present data suggest that inactivation of the FHIT gene by loss of expression is one of the important molecular events associated with the genesis of ovarian carcinoma, especially of high-grade serous carcinoma. © 2001 Cancer Research Campaign http://www.bjcancer.com

Altered Expression of the Fragile Histidine Triad Gene in Primary Gastric Adenocarcinomas

Genomic alterations and abnormal expression of the fragile histidine triad (FHIT) gene in gastric carcinomas were examined to determine whether the FHIT gene is actually a frequent target for alteration during gastric carcinogenesis. To correlate DNA and RNA lesions of the FHIT gene with the effect on FHIT protein expression, we have investigated the FHIT gene for loss of heterozygosity (LOH), aberrant transcripts, point mutations, and protein expression in 35 gastric adenocarcinomas. Allelic loss at D3S1300 was detected in 7 of 33 (21%) informative cases. Aberrant transcripts, with deletions and/or insertions, were observed in 20 of 35 (57.1%) cases and resulted from alternative splicing through exon skipping and/or insertion of the FHIT intron 5 sequence or activation of the cryptic splice site. Point mutations were not found in the FHIT coding region but detected in noncoding exon 2, 3, 4, or 5 of eight aberrant transcripts. Significant reduction of FHIT protein expression was observed in 22 of 35 (62.9%) cases. Aberrant FHIT transcription was shown to be associated with loss of FHIT protein expression. However, aberrant FHIT transcripts themselves were not associated with any clinicopathological parameters, such as age, sex, tumor site, or clinical stage. Moreover, there was no association between the presence of LOH at D3S1300 and the expression of aberrant FHIT transcripts. Nevertheless, high frequency of aberrant FHIT transcripts, significant rate of LOH at D3S1300, and altered expression of the FHIT protein indicate that alterations of the FHIT gene can play an important role in gastric carcinogenesis.

Fragile Histidine Triad (FHIT) Gene Abnormalities in Lung Cancer

Lung cancer is the most common cause of cancer death in the world. In recent years, enormous progress has been made in understanding the molecular and cellular biology of lung cancer. The fragile histidine triad (FHIT) gene, a candidate tumor-suppressor gene, was recently identified at chromosome 3p14.2, spanning the FRA3B common fragile site. Frequent allelic losses as well as homozygous deletions have been described at the FHIT locus, making FHIT a strong candidate as a tumor-suppressor gene. However, the occurrence of mutations is very rare. Aberrant FHIT transcripts, including deletions of exons, insertions between exons, and insertions replacing exons, are detected in a high percentage of lung tumors. Reduction or complete loss of FHIT expression by immunohistochemical testing is seen in about 30%-70% of non–small-cell lung cancer and in about 20% of bronchial biopsies from chronic smokers without evidence of lung cancer. This finding supports the theory that FHIT is a molecular target of tobacco smoke carcinogens. However, the location of the gene in one of the most fragile sites of the human genome and the paucity of mutations have led to an alternative hypothesis that abnormalities of the gene are bystander effects resulting from disruption of the FRA3B locus. Thus, the function of FHIT as a candidate tumor-suppressor gene is still controversial, and additional studies are necessary to clarify the role of FHIT in lung cancer pathogenesis.

Fragile histidine triad gene expression in primary prostate cancer and in an in vitro model

BACKGROUND The fragile histidine triad (FHIT) is frequently deleted and altered in many human cancers. Replacement of the FHIT gene into cancer cell lines lacking FHIT expression results in loss of tumorigenicity and tumor growth. METHODS We investigated the status and function of the FHIT gene in the etiology of prostate carcinoma, utilizing human prostate cancer tissues and cell lines and the multistep human prostate epithelial (HPE) cell tumor model. RESULTS In primary cancers, either no FHIT protein expression or greatly reduced expression was observed in the tumor cells, while FHIT was expressed at high levels in the adjacent normal prostate epithelia. No aberrant FHIT transcripts were observed in normal HPE cells. Aberrant transcripts were observed in the immortalized and nontumorigenic HPV-18 C-1 cell line. A tumor cell line (129 Nu 5002-1) derived from chemical transformation of HPV-18 C-1 cells did not express the FHIT gene. Immunoblot analysis of FHIT protein levels confirmed the absence of FHIT expression in the 129 Nu 5002-1 tumor cell line. Among the metastatic prostate cancer cell lines, PC-3, DU-145, and S7 exhibited aberrant transcripts, but the LNCaP cell line (early passage) was normal. Upon cloning of the cDNA and determining the DNA sequence of the PCR fragments, we observed specific alterations such as deletions and insertions in the aberrant transcripts. A majority of prostate cancer cell lines expressed the normal-sized transcript in addition to the aberrant transcripts. CONCLUSIONS Our results indicate that alterations in the FHIT gene represent an early event in prostate carcinogenesis. Prostate 43:101–110, 2000. © 2000 Wiley-Liss, Inc.

Anomalous Transcripts and Allelic Deletions of the FHIT Gene in Human Esophageal Cancer

The fragile histidine triad (FHIT) gene is localized on chromosome 3p14 and spans the common fragile site FRA3B. Even though its role in carcinogenesis is still unclear, this gene is frequently inactivated by carcinogen-induced intragenic deletions in many types of cancers, and FHIT abnormal transcripts are found in many primary tumors and tumor-derived cell lines. We evaluated FHIT gene involvement in 39 esophageal carcinomas (18 adenocarcinomas [AC}, 21 squamous cell carcinomas [SCC]) by both reverse transcriptase–polymerase chain reaction (RT-PCR) amplification and loss of heterozygosity analysis (LOH). Thirty cases (77%) displayed either aberrant FHIT transcripts (12 cases) and/or LOH (24 cases); among these, only 6 samples displayed both aberrant transcripts and LOH, thus suggesting that the two events are probably independent. Moreover, LOH was significantly higher in SCC (80%) than in AC (44%), and because most of our patients are heavy smokers and/or alcohol consumers, these results suggest that the FHIT gene might be a common target for carcinogens also in the esophagus.

Fragile histidine triad gene expression in primary prostate cancer and in an in vitro model.

The fragile histidine triad (FHIT) is frequently deleted and altered in many human cancers. Replacement of the FHIT gene into cancer cell lines lacking FHIT expression results in loss of tumorigenicity and tumor growth. We investigated the status and function of the FHIT gene in the etiology of prostate carcinoma, utilizing human prostate cancer tissues and cell lines and the multistep human prostate epithelial (HPE) cell tumor model. In primary cancers, either no FHIT protein expression or greatly reduced expression was observed in the tumor cells, while FHIT was expressed at high levels in the adjacent normal prostate epithelia. No aberrant FHIT transcripts were observed in normal HPE cells. Aberrant transcripts were observed in the immortalized and nontumorigenic HPV-18 C-1 cell line. A tumor cell line (129 Nu 5002-1) derived from chemical transformation of HPV-18 C-1 cells did not express the FHIT gene. Immunoblot analysis of FHIT protein levels confirmed the absence of FHIT expression in the 129 Nu 5002-1 tumor cell line. Among the metastatic prostate cancer cell lines, PC-3, DU-145, and S7 exhibited aberrant transcripts, but the LNCaP cell line (early passage) was normal. Upon cloning of the cDNA and determining the DNA sequence of the PCR fragments, we observed specific alterations such as deletions and insertions in the aberrant transcripts. A majority of prostate cancer cell lines expressed the normal-sized transcript in addition to the aberrant transcripts. Our results indicate that alterations in the FHIT gene represent an early event in prostate carcinogenesis.

Restored expression of fragile histidine triad protein and tumorigenicity of cervical carcinoma cells.

Allelic losses in the short arm of chromosome 3 are common in cervical carcinomas. The fragile histidine triad (FHIT) gene at chromosome region 3p14.2 is a candidate tumor suppressor gene that may play a role in cervical tumorigenesis. We and others have identified aberrant FHIT transcripts and frequent loss of Fhit protein expression in primary cervical cancers and high-grade noninvasive lesions but not in normal cervical tissues. The altered expression of FHIT may be due to somatic mutations or integration of human papillomavirus DNA at the FHIT locus. The purpose of this study was to determine whether ectopic expression of Fhit can suppress the tumorigenic properties of cervical cancer cells. We employed infection with recombinant retroviruses as well as transfection of plasmid DNA to restore Fhit protein expression in cervical cancer cell lines lacking full-length FHIT transcripts and endogenous Fhit protein. The effects of Fhit expression on tumor cell morphology, anchorage-independent growth, and tumorigenicity in nude mice were examined. Stable overexpression of Fhit had no discernible effect on the tumorigenic properties of two cervical carcinoma cell lines or on a lung carcinoma cell line previously reported by others to be suppressed for tumorigenicity by Fhit. Restoration of Fhit expression does not suppress anchorage-independent growth or tumorigenicity of cervical carcinoma cell lines. However, it remains possible that FHIT inactivation may be important early in cervical tumor progression or that FHIT may suppress tumorigenesis in ways distinct from those measured by the assays employed in this study.

Clinicopathologic Features and FHIT Gene Expression in Sporadic Colorectal Adenocarcinomas

Background: The putative tumour suppressor gene FHIT (fragile histidine triad) spans the common fragile site FRA3B, which is highly susceptible to breaks and deletions induced by genotoxic agents. Tumours associated with exposure to carcinogens, such as colorectal adenocarcinomas, should be particularly susceptible to alterations in the FHIT gene. We studied the frequency of FHIT alterations and their correlations with clinicopathologic features in sporadic colon carcinomas. Methods: FHIT expression was investigated by reverse transcription polymerase chain reaction in 56 primary sporadic colorectal carcinomas. The same tumours and matched normal tissues were also investigated for loss of heterozygosity by using two markers located inside the FHIT gene. Results: Twenty-nine of 56 tumours (51.8%) expressed aberrant FHIT transcripts. Four tumours had absence or nearly undetectable levels of the normal-sized FHIT transcript. Sequencing analysis of the altered transcripts showed FHIT mRNA lacking one or more exons, more frequent deletions of exons 4-5-6 or 4-5-6-7-8. At the genomic level 46.4% (13 of 28) of the cases showed alterations involving FHIT locus. We did not find any correlation between FHIT gene alterations and clinicopathologic characteristics of the tumours. Conclusions: Since the FHIT gene is frequently altered, its role in the molecular pathogenesis of sporadic colon carcinoma deserves further investigation.