Fhit Expression Research Articles

Fhit loss in familial breast cancer: is loss of DNA repair function linked to alterations at chromosome fragile sites?

The FHIT gene at 3p14.2 encompasses the common fragile site, FRA3B, and is involved in frequent chromosome rearrangements in human cancers. Fhit protein expression is reduced or lost in the majority of esophageal, lung, gastric, cervical, pancreatic, kidney and bladder cancers, and a large fraction of other cancers. Fhit expression in sporadic breast cancers has been studied by several groups, and reported to show alteration in expression of Fhit in 30-50%. Because familial breast cancers were reported to show a higher frequency of LOH at 3p14.2 than sporadic breast cancers, we were interested in whether common fragile regions might be targets for repair by the Brca1 and Brca2 proteins, and might thus be a downstream target in BRCA1- and BRCA2-induced familial breast tumors. We studied a panel of Brca2-deficient breast tumors and showed that only 18% expressed Fhit strongly, compared with 48% of sporadic tumors (P = 0.002). Very recently we completed a similar study of BRCA1 familial tumors, and observed that only 9% of these tumors showed strong expression versus more than 40% of sporadic breast tumors (P <0.001, odds ratio 0.09). We conclude that loss of BRCA1 and BRCA2 functions affect stability of the FHIT/FRA3B locus and possibly other fragile loci.

Restored expression of Fhit protein in Fhit-minus breast cancer cells

The gene FHIT, encompassing the FRA3B fragile site, is located in a region of chromosome 3p14.2 that is often deleted in several types of epithelial cancers and, therefore, it has been investigated as a candidate tumor suppressor. In breast cancer inactivation of FHIT occurred in 70% of the patients, and it is caused by both alterations in the regulation of Fhit expression and by deletions of the gene. Moreover, analysis of 500 cases of breast carcinomas with 20 years of follow up demonstrated that loss of Fhit protein is associated with high proliferative, large and undifferentiated tumors, even though Fhit is not a prognostic factor. In order to elucidate the possible role of FHIT as a tumor suppressor in breast cancer and to identify its mechanisms, Fhit protein-negative breast cancer cell lines lacking endogenous protein expression were stable transfected with FHIT cDNA. Stable transfectant clones showed no alteration in cell morphology and in in vitro anchorage-dependent and independent proliferation. A significant delay in the tumor growth in nude mice was observed for some Fhit-positive clones; in an additional case the outgrowing of the tumor was due to loss of Fhit expression in vivo. Interestingly, some Fhit-positive clones are able to develop tumors in vivo despite high stable Fhit expression, prompting us to investigate the different mechanisms between the two types of Fhit-expressing clones. Supported by AIRC.

A fhit-ing end to tumor development

Most gene therapy approaches to cancer to date have concentrated on the elimination of pre-existing tumor cells. However, as more genes are identified that when mutated predispose individuals to the development of cancer, alternative strategies are now being considered. Some of these strategies are based on the premise that a normal version of, for example, a tumor suppressor gene expressed in susceptible tissues, could prevent the development or proliferation of tumor cells. The feasibility of this approach has recently been shown by Dumon et al.1 Dumon K.R. et al. FHIT gene therapy prevents tumor development in Fhit-deficient mice. Proc. Natl. Acad. Sci. USA. 2001; 98: 3340-3351 Crossref PubMed Scopus (150) Google Scholar using a knockout transgenic mouse model that shows an increased susceptibility to the formation of tumors as a result of inactivation of the tumor suppressor gene fhit. In humans FHIT maps to a common fragile site on chromosome 3. Chromosomal rearrangements effecting this region and thus the FHIT gene are present in many cancers including esophageal and gastric cancer. Fong and co-workers 2 Fong L.Y.Y. et al. Muir–Torre-like syndrome in Fhit-deficient mice. Proc. Natl. Acad. Sci. USA. 2000; 97: 4742-4747 Crossref PubMed Scopus (186) Google Scholar have previously shown that heterozygous mice defective for fhit show an increased predeposition to carcinogen-induced tumor development in the esophagus and forestomach compared with wild-type mice. To test whether FHIT expression could prevent the formation of tumors in Fhit-defective mice, adenovirus (Ad) and adeno-associated virus (AAV) vectors were used to deliver the human FHIT gene to the esophagus and forestomach of treated-Fhit heterozygous mice treated with the carcinogen N-nitrosomethylbenzylamine. Both the carcinogen and the viral vectors were administered via oral gavage. FHIT immunohistochemistry confirmed transduction of intestinal cells in the esophagus and forestomach by both the Ad–FHIT and AVV–FHIT vectors. Gross and histological examination of mice ten weeks after viral administration showed a reduction in the number of tumors and focal hyperplastic lesions in FHIT-treated animals compared with control animals. This reduction was particularly emphatic in the forestomach and the squamocolumnar junction region – a region corresponding to the human esophago-gastric junction. A reduction in cellular proliferation was also noted in the FHIT-treated animals. These data suggest that FHIT expression in susceptible cells of the esophago-gastric tract could be used to prevent the development of tumor cells. It will be interesting to see if this approach could also be applied to the prevention or treatment of other cancers associated with the loss of FHIT gene activity including lung cancer.

Induction of the common fragile site FRA3B does not affect FHIT expression.

A long-standing issue concerns the extent to which fragile sites predispose to cancer-associated chromosomal rearrangements. The FHIT gene at chromosome 3p14.2 spans the most common fragile site, FRA3B, in the human genome. Although the FHIT gene is altered in many human cancers, its status as a tumor suppressor gene has remained controversial, particularly since functional studies provided contradictory results. It had been suggested the FHIT alterations result from FRA3B induction promoted by the interference of carcinogens with DNA replication. Here we investigated the effect of FRA3B induction on FHIT expression. Common fragile sites were induced by treatment with aphidicolin and scored cytogenetically. FHIT transcription was analysed by RT--PCR and RNase protection analysis. Unexpectedly, FHIT transcription proceeded unchanged after fragile site induction. Aberrant FHIT transcripts lacking one or more exons were not observed. Moreover, Western blots revealed that the levels of FHIT prior to and following fragile site induction was unchanged, whereas p53 was found at elevated levels after induction. FRA3B induction thus has no direct effect on FHIT transcription and translation.

Analysis of the fragile histidine triad ( FHIT) gene in lobular breast cancer

The fragile histidine triad ( FHIT) gene is a candidate tumour suppressor gene in breast and other cancers. We investigated deletions within the FHIT gene in lobular breast cancer and found that 16% of cases showed loss of heterozygosity (LOH) within the gene. We compared LOH within FHIT in lobular and ductal breast tumours and found a significant association between LOH at FHIT and the ductal histological type ( P<0.001). To determine whether genomic alteration of the FHIT gene in lobular breast cancer leads to Fhit inactivation we have assessed the level of Fhit expression by immunohistochemical detection and determined that 27% (15 of 55) consecutive sporadic lobular tumours showed negative or reduced Fhit expression. A significant association was found between LOH at the FHIT gene and reduced Fhit expression in lobular and ductal tumours ( P=0.025 and P=0.001, respectively). Thus, genetic alterations within the FHIT gene, leading to loss of Fhit protein, may play an important role in the carcinogenesis of a significant number of sporadic lobular breast cancers, even though the apparent frequency of genomic alterations within the gene is lower than in ductal breast cancer.

Fhitness and cancer in the mouse

The human FHIT gene is located at 3p14.2, a position on the short arm of chromosome 3 that includes the most fragile site in the human genome and spans a t(3;8) translocation that predisposes to early onset, clear cell renal carcinoma. FHIT deletions are extremely common in human cancers, especially those that arise from lung and stomach epithelia exposed to environmental carcinogens. Nonetheless, because FHIT spans a fragile site and tumors usually lose FHIT by deletion rather than point mutation, some researchers have argued that FHIT deletions are not a cause of cancer but rather a consequence of genome instability. Although the early kinetics of FHIT inactivation in lung carcinogenesis, and the fact that re-expression of Fhit protein induces apoptosis in parallel with suppressing tumor formation, support assignment of FHIT as a tumor suppressor, many cancer geneticists consider the knockout mouse to be the ultimate test.If FHIT inactivation in humans is merely a consequence of genome instability, then inactivation of Fhit in the mouse would not be expected to effect carcinogenesis. On the other hand, if FHIT loss in humans does contribute to cell transformation, then murine Fhit− animals might be expected to develop tumors, potentially in the same organs in which human FHIT− tumors appear. This was precisely the result obtained by Fong et al.1xMuir–Torre-like syndrome in Fhit-deficient mice. Fong, L.Y.Y. et al. Proc. Natl. Acad. Sci. U. S. A. 2000; 97: 4742–4747Crossref | PubMed | Scopus (162)See all References1, all the more striking because this was after genetically inactivating only one Fhit allele in the mouse. Because the murine Fhit locus, like its syntenic human counterpart, is fragile, mice that were heterozygous for inactivation of Fhit developed stomach and sebaceous tumors when given N-nitrosomethylbenzylamine intragastrically. Ten weeks after treatment, 10 of 12 heterozygous mice had tumors of the forestomach, and 7 of 12 had sebaceous tumors; these tumors lacked Fhit protein. Among eight identically treated wild-type mice, one developed a tumor in the forestomach and none developed a sebaceous tumor. The combination of visceral and sebaceous tumors in Fhit heterozygous mice struck these researchers as similar to human Muir–Torre syndrome (MTS), a variant of hereditary nonpolyposis colorectal cancer, and they showed that some human MTS tumors are Fhit.Whereas MTS usually arises from inherited defects in mismatch repair genes, the full complement of genetic changes in MTS tumors is not known. The phenotype of Fhit heterozygous mice not only demonstrates that loss of Fhit predisposes to carcinogenesis, but also suggests that an intact mismatch repair system might either protect the FHIT locus or maintain Fhit expression in humans.

The expression of Fhit protein is related inversely to disease progression in patients with breast carcinoma

The FHIT gene, located at human chromosome 3p14.2, frequently is deleted in a number of human tumors, including breast carcinoma. Its protein product (Fhit) is presumed to have tumor suppressor function. Loss of expression of a tumor suppressor gene is an important step in tumor progression from premalignant, to in situ, to invasive carcinoma. In the current study, Fhit expression was examined in invasive carcinomas and in epithelial lesions representing stages of carcinoma progression in 50 mastectomy specimens using immunohistochemical methods. Normal ductal and lobular epithelium consistently and strongly expressed Fhit. A complete loss of or a significant reduction in Fhit expression was observed in 72% of breast carcinomas. A statistically significant, negative correlation in Fhit expression among the stages of disease progression in Fhit negative breast carcinomas was observed (normal epithelium > hyperplasia > atypical hyperplasia and carcinoma in situ > invasive carcinoma), whereas no loss of Fhit expression in precursor lesions was observed in Fhit positive tumors. These observations are consistent with the observed role of FHIT as a tumor suppressor gene in the pathogenesis of specific subsets of carcinomas.

The expression of Fhit protein is related inversely to disease progression in patients with breast carcinoma

BACKGROUND The FHIT gene, located at human chromosome 3p14.2, frequently is deleted in a number of human tumors, including breast carcinoma. Its protein product (Fhit) is presumed to have tumor suppressor function. Loss of expression of a tumor suppressor gene is an important step in tumor progression from premalignant, to in situ, to invasive carcinoma. METHODS In the current study, Fhit expression was examined in invasive carcinomas and in epithelial lesions representing stages of carcinoma progression in 50 mastectomy specimens using immunohistochemical methods. RESULTS Normal ductal and lobular epithelium consistently and strongly expressed Fhit. A complete loss of or a significant reduction in Fhit expression was observed in 72% of breast carcinomas. A statistically significant, negative correlation in Fhit expression among the stages of disease progression in Fhit negative breast carcinomas was observed (normal epithelium > hyperplasia > atypical hyperplasia and carcinoma in situ > invasive carcinoma), whereas no loss of Fhit expression in precursor lesions was observed in Fhit positive tumors. CONCLUSIONS These observations are consistent with the observed role of FHIT as a tumor suppressor gene in the pathogenesis of specific subsets of carcinomas. Cancer 2000;88:1378–83. © 2000 American Cancer Society.

Analysis of Fhit expression in stages of breast cancer progression

Analysis of Fhit expression in stages of breast cancer progression

Loss of Fhit expression in non-small-cell lung cancer: correlation with molecular genetic abnormalities and clinicopathological features.

The FHIT gene is located at a chromosomal site (3p14.2) which is commonly affected by translocations and deletions in human neoplasia. Although FHIT alterations at the DNA and RNA level are frequent in many types of tumours, the biological and clinical significance of these changes is not clear. In this study we aimed at correlating loss of Fhit protein expression with a large number of molecular genetic and clinical parameters in a well-characterized cohort of non-small-cell lung cancers (NSCLCs). Paraffin sections of 99 non-small-cell carcinomas were reacted with an anti-Fhit polyclonal antibody in a standard immunohistochemical reaction. Abnormal cases were characterized by complete loss of cytoplasmic Fhit staining. The Fhit staining results were then correlated with previously obtained clinical and molecular data. Fifty-two of 99 tumours lacked cytoplasmic Fhit staining, with preserved reactivity in adjacent normal cells. Lack of Fhit staining correlated with: loss of heterozygosity (LOH) at the FHIT 3p14.2 locus, but not at other loci on 3p; squamous histology; LOH at 17p13 and 5q but not with LOH at multiple other suspected tumour suppressor gene loci; and was inversely correlated with codon 12 mutations in K- ras. Fhit expression was not correlated overall with a variety of clinical parameters including survival and was not associated with abnormalities of immunohistochemical expression of p53, RB, and p16. All of these findings are consistent with loss of Fhit protein expression being as frequent an abnormality in lung cancer pathogenesis as are p53 and p16 protein abnormalities and that such loss occurs independently of the commitment to the metastatic state and of most other molecular abnormalities. © 2000 Cancer Research Campaign

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.

Loss of FHIT Expression in Transitional Cell Carcinoma of the Urinary Bladder

Cytogenetic and loss of heterozygosity (LOH) studies demonstrated chromosome 3p deletions in transitional cell carcinoma (TCC). We recently cloned the tumor suppressor gene FHIT (fragile histidine triad) at 3p14.2, one of the most frequently deleted chromosomal regions in TCC of the bladder, and showed that it is the target of environmental carcinogens. Abnormalities at the FHIT locus have been found in tumors of the lung, breast, cervix, head and neck, stomach, pancreas, and clear cell carcinoma of the kidney. We examined six TCC derived cell lines (SW780, T24, Hs228T, CRL7930, CRL7833, and HTB9) and 30 primary TCC of the bladder for the integrity of the FHIT transcript, using reverse transcriptase-polymerase chain reaction (RT-PCR) to investigate a potential role of the FHIT gene in TCC of the bladder. In addition, we tested expression of the Fhit protein in the six TCC-derived cell lines by Western blot analysis and in 85 specimens of primary TCCs by immunohistochemistry. Three of the six cell lines (50%) did not show the wild-type FHIT transcript, and Fhit protein was not detected in four of the six cell lines (67%) tested. Fhit expression also was correlated with pathological and clinical status. A significant correlation was observed between reduced Fhit expression and advanced stage of the tumors. Overall, 26 of 30 (87%) primary TCCs showed abnormal transcripts. Fhit protein was absent or greatly reduced in 61% of the TCCs analyzed by immunohistochemistry. These results suggested that loss of Fhit expression may be as important in the development of bladder cancer as it is for other neoplasms caused by environmental carcinogens.

Fhit expression in gastric adenocarcinoma

The FHIT gene is inactivated by deletion in a large fraction of human tumors, including gastric carcinomas, and the Fhit protein has been proposed to act as a tumor suppressor in multiple tumor types. A large fraction of gastric adenocarcinomas have lost expression of the candidate tumor suppressor protein, Fhit, whereas normal gastric epithelial cells are strongly positive and Fhit loss has been found to correlate with alterations of the FHIT locus. Because the majority of gastric tumors in the current study were found to be entirely negative for Fhit protein, it is possible that alteration of the carcinogen-susceptible fragile region within the FHIT gene is an early event in gastric carcinoma, as it is in lung carcinoma. To determine whether the absence of Fhit protein correlates with expression of tumor markers or with clinical parameters, such as grade, stage, and survival time, the authors assessed Fhit expression using immunohistochemistry in a well characterized set of 55 gastric adenocarcinomas resected over several years, with longitudinal follow-up of patients for outcome. In this set of 55 gastric cancers, the absence of Fhit protein correlated with higher tumor stage (P = 0.003) and higher histologic grade (P = 0.007). In addition, patients whose tumors had lost expression of Fhit died of disease significantly earlier than those with Fhit positive tumors (P = 0.017). The absence of Fhit expression did not correlate with the expression of any tumor markers. Larger studies will be required to elucidate further the relation between tumor stage, grade, and Fhit loss and to determine whether inclusion of Fhit antiserum in immunophenotyping of gastric adenocarcinomas will be a useful indicator of post-diagnosis prognosis.

FHIT alterations in cancerous and non-cancerous cervical epithelium.

We have reported a significant frequency of an alteration of the fragile histidine triad (fhit) gene in squamous-cell carcinoma of the uterine cervix (series 1). To further define the role of fhit alteration in the development of cervical carcinoma, we surveyed 36 normal cervical epithelium, 22 cervical intra-epithelial neoplasias (CINs) and 20 additional cases of invasive cervical carcinomas (series 2). fhit transcripts were analyzed using reverse-transcription-polymerase-chain-reaction amplification and sequencing. Loss of expression of fhit was observed in 14 of 48 (29%) invasive carcinomas (8/28, series 1; 6/20, series 2) but not in any normal squamous epithelia or CINs analyzed. Abnormal fhit transcripts, including deletions and/or insertions, were observed in 12 of 48 (25%) invasive carcinomas (9/28, series 1; 3/20, series 2), 6 of 22 (27%) CINs, and 10 of 40 (25%) normal squamous epithelia (0/4, series 1; 10/36, series 2). Point mutation was detected in 9 of 48 (19%) cervical carcinomas (8/28, series 1; 1/20, series 2). Inactivation in both alleles was observed in 18 of 48 cervical carcinomas (38%), but not in any of 22 CINs or 40 normal squamous epithelia. Loss or impaired expression of the fhit-gene product was detected in 13 of 30 (43%) cervical carcinomas by immunohistochemistry, whereas all 6 normal cervical epithelia, or 22 CINs, expressed fhit protein. There was a strong association of impaired fhit protein expression with the disruption of normal fhit transcript in cervical carcinoma. No apparent correlation was observed between fhit inactivation and HPV infection. Our results suggest that fhit-gene inactivation occurs, not as an initiating event, but rather as a later event in cervical carcinogenesis, when the cervical tumor has acquired an invasive character.

Loss or reduction of Fhit expression in renal neoplasias: Correlation with histogenic class

Involvement of the 3p14.2 region of chromosome 3 in kidney cancers was suggested 20 years ago, when a reciprocal constitutional translocation, t(3;8)(p14.2;q24), was shown to segregate with bilateral clear cell renal carcinoma in 3 generations of 1 family. The FHIT gene that is interrupted at 3p14.2 by the t(3;8) translocation has been isolated, characterized, and shown to be frequently altered, mainly by internal deletion, in carcinomas or cancer-derived cell lines of the lung, stomach, pancreas, esophagus, cervix, and colon. Although up to 90% of sporadic clear cell renal carcinomas, representing ∼70% of adult renal carcinomas, exhibit loss of FHIT alleles, FHIT gene alterations have been documented for only a few renal cell carcinoma-derived cell lines. Nevertheless, more than 50% of clear cell carcinomas were recently shown to express little or no Fhit protein, unlike the normal kidney tubule epithelium, which is uniformly strongly positive for Fhit expression. We have extended our immunohistochemical study of expression of Fhit protein to the spectrum of histopathologic subtypes of adult renal tumors. There is an apparent continuum of Fhit expression from the 100% strongly positive oncocytomas through mostly positive papillary and chromophobe to the mostly negative clear cell and sarcomatoid to the negative or predominantly negative collecting duct renal carcinomas. This pattern of diminishing Fhit expression correlates with reported frequency of 3p allele loss in renal carcinomas and may parallel the potential for aggressive behavior of tumors, as suggested by the abundant Fhit expression in the benign oncocytomas and the near absence of Fhit expression in sarcomatoid and collecting duct RCCs.

Pattern of FHIT gene expression in normal and leukaemic cells.

Chromosomal aberrations and inactivation of tumour suppressor genes are frequent in acute leukaemia. To determine whether the FHIT gene is involved in the development of leukaemia, we examined the FHIT transcript in 65 leukaemia cell lines, 5 fresh acute leukaemia patients at diagnosis and in complete remission, normal peripheral blood lymphocytes obtained from 14 healthy volunteers and Epstein-Barr (EB) virus transformed 5 B-cell lines (EB-lines), using nested reverse transcription-polymerase chain reaction and direct sequencing. The transcripts were classified into 4 patterns: pattern I revealed the normal transcripts only, pattern II the altered transcripts in addition to the normal transcripts, pattern III the altered transcripts without the normal transcripts and pattern IV an absence of normal and altered FHIT transcripts. Nineteen cell lines were classified as pattern I, 32 as pattern II, 2 as pattern III and 12 as pattern IV. The frequency of loss of FHIT expression (pattern III or IV) varied in each type of leukaemia cell line; the order ranked from the highest incidence was acute myeloid leukaemia (AML), T-cell acute lymphoblastic leukaemia (T-ALL), B-precursor ALL, B-ALL, and chronic myeloid leukaemia (CML). No genomic rearrangement was found in any samples examined. All of 5 patients showed same pattern II FHIT transcripts at 2 different stages of the disease. All normal peripheral blood lymphocytes and EB-lines were classified as pattern I or II. Our results suggested that patterns III and IV of FHIT transcripts might be associated with the development of a subset of leukaemia, while pattern II which has so far been reported as an aberrant transcript in varieties of malignant tumours might not be associated with leukaemogenesis.

Role of FHIT in human cancer.

Through investigation of hemizygous and homozygous deletions in common human cancers, including lung cancer, we have cloned and characterized a gene at chromosome region 3p14.2, FHIT, that is inactivated in epithelial tumors, particularly in tumors resulting from exposure to environmental carcinogens. In some tumors, particularly those associated with environmental carcinogens, alterations in the FHIT gene occur quite early in the development of cancer. In other cancers, Fhit inactivation seems to be a later event, possibly associated with progression to more aggressive neoplasias. Thus, detection of Fhit expression by immunohistochemistry in premalignant and malignant tissues may provide important diagnostic and prognostic information.

Different gene expression of MDM2, GAGE-1, -2 and FHIT in hepatocellular carcinoma and focal nodular hyperplasia.

Overexpression and/or mutations of oncogenes, tumour suppressor genes and tumour rejection genes have been observed in several human malignancies. Their analyses might be of diagnostic importance. Therefore, malignant hepatocytes derived from hepatocellular carcinoma (HCC) tissue as well as non-malignant hepatocytes derived from focal nodular hyperplasia (FNH) were studied. Samples containing normal human hepatocytes (HC) served as controls. Cellular material was obtained by fine-needle aspiration biopsy guided by ultrasound. Cells were analysed for expression and mutation of the oncogene MDM2, the genes GAGE-1, -2 coding for tumour-associated antigens and the candidate tumour suppressor gene FHIT. Different patterns of non-mutant FHIT transcripts including precise deletion of exons were found in 7/10 HCC, 2/10 FNH and 2/10 HC. However, expression of non-mutant GAGE-1, -2 RNA was demonstrated exclusively in 6/10 HCC samples. Further genetic features specific of HCC were point mutations in a zinc-finger motif of MDM2 (3/10 HCC samples). Neither GAGE-1, -2 expression nor MDM2 mutations were observed in the FNH samples, or in normal hepatocytes. Our findings suggest that occurrence of variable FHIT transcripts is not restricted to hepatic malignant tumours. In contrast, MDM2 mutations and GAGE-1, -2 expression were associated with HCC specimens. Therefore, the RT-PCR assays for GAGE-1, -2 and MDM2 might be useful adjuncts in cytodiagnosis of liver neoplasms. © 1999 Cancer Research Campaign

Expression of FHIT in primary cultures of human epithelial ovarian tumors and malignant ovarian ascites.

Abnormal FHIT gene expression has been reported in a variety of epithelial tumors shown to harbor deletions of chromosome 3p14, the chromosomal assignment of this gene. Recently, we described loss of heterozygosity of 3p in a subset of epithelial ovarian cancers. To investigate a potential role of the FHIT gene in ovarian cancer, we examined primary cell cultures derived from normal ovarian surface epithelium, ovarian tumors, and the cellular fraction of malignant ascites to determine the expression of FHIT by using reverse transcription-polymerase chain reaction. Included in this analysis were four spontaneously immortalized cell lines: three derived from malignant epithelial ovarian tumors (TOV21G, TOV112D, and TOV81D) and one from malignant ovarian ascites (OV90). OV90 was previously shown to harbor a deletion of the whole p arm of chromosome 3. The FHIT transcript was not detectable in two of 11 primary cultures derived from normal ovarian surface epithelium or in a primary culture derived from malignant ovarian ascites, whereas the remaining samples (34 malignant, eight borderline, and three benign specimens), exhibited identical expression patterns. In each case, this pattern was consistent with the co-expression of a normal FHIT transcript and a smaller transcript. DNA sequencing revealed that the abnormal-sized message lacked exons 4-7 (inclusive), which were deleted at their exact intron-exon splice sites. The aberrant-sized transcript was detectable by Northern blot analysis. There was no concordance between FHIT expression and loss of heterozygosity at the FHIT locus. Northern blot analysis also revealed that FHIT was differentially expressed, and the spontaneously immortalized cell lines TOV21G and TOV112D showed the highest level of expression. Because the same reverse transcription-polymerase chain reaction expression pattern was observed in both normal and tumor-derived primary cell cultures, these results argue against a significant role for FHIT in epithelial ovarian tumorigenesis.

Molecular alterations to human chromosome 3p loci in neuroendocrine lung tumors.

The origins of and interrelations between low grade and high grade neuroendocrine lung tumors, typical and atypical carcinoids, and small cell lung carcinoma (SCLC) have not been elucidated. Karyotypic and molecular genetic studies have demonstrated deletions in 3p in 100% of SCLCs and the candidate lung tumor suppressor gene, FHIT, at 3p14.2 is not expressed in the majority of SCLCs. Similar studies of typical and atypical carcinoids could clarify the interrelations among these tumors. For molecular genetic analyses, archival carcinoids and paired normal cells were microdissected from paraffin sections, deparaffinized, and DNA prepared. Oligonucleotide primer pairs for 12 microsatellite markers mapping between 3p14.2 and 3p21.3 were used to amplify allelic DNA fragments from 13 typical and 6 atypical carcinoids. In addition, an independent series of archival sections of carcinoids and SCLCs was tested by immunohistochemistry for expression of Fhit protein. Of the six atypical carcinoids examined, three had lost an allele at all informative markers, whereas one had lost alleles in two distinct regions and two showed allele loss in a subregion of the chromosome region tested. Of the 13 typical carcinoids, 3 showed allele loss at only 1 or 2 loci each. Typical carcinoids, similar to normal lung epithelia, were strongly positive for the cytoplasmic Fhit protein, SCLCs were uniformly negative, and atypical carcinoids appeared to express an intermediate level of Fhit protein. Loss of heterozygosity at 3p14.2-p21.3 is significantly more extensive in all atypical carcinoids. Atypical carcinoids, which exhibit clinicopathologic features intermediate between typical carcinoids and small cell carcinomas and have been considered well differentiated neuroendocrine carcinomas, also are intermediate between typical carcinoids and SCLC on the basis of extent of loss of 3p alleles and reduced expression of Fhit protein.