FHIT: from gene discovery to cancer treatment and prevention

Significance and implications of FHIT gene expression and promoter hypermethylation in acute lymphoblastic leukemia (ALL)

BACKGROUND

Fragile histidine triad (FHIT) has been documented to play a vital role in various cancers including acute lymphoblastic leukemia (ALL). Keeping in view the plausible role of FHIT gene, we aimed to examine DNA promoter hypermethylation and mRNA expression in ALL cases in Kashmir (North India).

METHODS

A total of 66 cases of ALL were analyzed for FHIT mRNA expression and promoter methylation by qRT-PCR and Methylation Specific-PCR (MS-PCR) respectively.

RESULTS

FHIT mRNA expression showed significantly decreased expression in ALL cases with mean fold change of 9.24 ± 5.44 as compared to healthy controls (p = 0.01). The pattern of FHIT deregulation in ALL cases differed significantly between decreased and increased expression (p < 0.0001). A threefold decreased expression was observed in 75% of ALL cases than healthy controls (- 3.58 ± 2.32). ALL patients with FHIT gene promoter hypermethylation presented significantly higher in 80% (53/66) of cases (p = 0.0005). The association of FHIT gene hypermethylation and its subsequent expression showed FHIT mRNA expression as significantly lower in ALL cases with hypermethylation (p = 0.0008). B-ALL cases exhibited a highly significant association between the methylation pattern and its mRNA expression (p = 0.000). In low range WBC group, a significant association was found between increased expression (26%) of the cases and methylated (4%)/unmethylated group 86% (p = 0.0006).

CONCLUSION

The present study conclude that FHIT gene hypermethylation and its altered expression may be linked in the pathogenesis of ALL and provide an evidence for the role of FHIT in the development of ALL.

Exploring the correlation between progression of human papillomavirus infection towards carcinogenesis and nutrition

Human papillomavirus (HPV) is a common sexually transmitted virus that can lead to the development of various types of cancer. While there are vaccines available to prevent HPV infection, there is also growing interest in the role of nutrition in reducing the risk of HPV-related cancers in HPV positive patients. Diet and nutrition play a critical role in maintaining overall health and preventing various diseases. A healthy diet can strengthen the immune system, which is essential for fighting off infections, including HPV infections, and preventing the growth and spread of cancer cells. Therefore, following a healthy diet and maintaining a healthy weight are important components of HPV and cancer prevention. This article explores the current scientific evidence on the relationship between nutrition and HPV, including the impact of specific nutrients, dietary patterns, and supplements on HPV infection toward cancer progression.

The Rosetta Stone Hypothesis-Based Interaction of the Tumor Suppressor Proteins Nit1 and Fhit

In previous studies, we have identified the tumor suppressor proteins Fhit (fragile histidine triad) and Nit1 (Nitrilase1) as interaction partners of β-catenin both acting as repressors of the canonical Wnt pathway. Interestingly, in D. melanogaster and C. elegans these proteins are expressed as NitFhit fusion proteins. According to the Rosetta Stone hypothesis, if proteins are expressed as fusion proteins in one organism and as single proteins in others, the latter should interact physically and show common signaling function. Here, we tested this hypothesis and provide the first biochemical evidence for a direct association between Nit1 and Fhit. In addition, size exclusion chromatography of purified recombinant human Nit1 showed a tetrameric structure as also previously observed for the NitFhit Rosetta Stone fusion protein Nft-1 in C. elegans. Finally, in line with the Rosetta Stone hypothesis we identified Hsp60 and Ubc9 as other common interaction partners of Nit1 and Fhit. The interaction of Nit1 and Fhit may affect their enzymatic activities as well as interaction with other binding partners.

Transcriptomic FHITlow/pHER2high signature as a predictive factor of outcome and immunotherapy response in non-small cell lung cancer

Introduction

In recent decades, the development of immunotherapy and targeted therapies has considerably improved the outcome of non-small cell lung cancer (NSCLC) patients. Despite these impressive clinical benefits, new biomarkers are needed for an accurate stratification of NSCLC patients and a more personalized management. We recently showed that the tumor suppressor fragile histidine triad (FHIT), frequently lost in NSCLC, controls HER2 receptor activity in lung tumor cells and that tumor cells from NSCLC patients harboring a FHIT^low/pHER2^high phenotype are sensitive to anti-HER2 drugs. Here, we sought to identify the transcriptomic signature of this phenotype and evaluate its clinical significance.

Materials and methods

We performed RNA sequencing analysis on tumor cells isolated from NSCLC (n=12) according to FHIT/pHER2 status and a functional analysis of differentially regulated genes. We also investigated the FHIT^low/pHER2^high signature in The Cancer Genome Atlas (TCGA) lung adenocarcinoma (LUAD) (n=489) and lung squamous cell carcinoma (LUSC) (n=493) cohorts and used the tumor immune dysfunction and exclusion (TIDE) model to test the ability of this signature to predict response to immune checkpoint inhibitors (ICI).

Results

We showed that up-regulated genes in FHIT^low/pHER2^high tumors were associated with cell proliferation, metabolism and metastasis, whereas down-regulated genes were related to immune response. The FHIT^low/pHER2^high signature was associated with the higher size of tumors, lymph node involvement, and late TNM stages in LUAD and LUSC cohorts. It was identified as an independent predictor of overall survival (OS) in LUAD cohort. FHIT^low/pHER2^high tumors were also predictive of poor response to ICI in both LUAD and LUSC cohorts.

Conclusion

These data suggest that ICI might not be a relevant option for NSCLC patients with FHIT^low/pHER2^high tumors and that anti-HER2 targeted therapy could be a good therapeutic alternative for this molecular subclass with poorer prognosis.

Squamous Cell Carcinoma of the Esophagus

Esophageal squamous cell carcinoma (ESCC) is common in the developing world with decreasing incidence in developed countries and carries significant morbidity and mortality. Major risk factors for ESCC development include significant use of alcohol and tobacco. Screening for ESCC can be recommended in high-risk populations living in highly endemic regions. The treatment of ESCC ranges from endoscopic resection therapy or surgery in localized disease to chemoradiotherapy in metastatic disease, and prognosis is directly related to the stage at diagnosis. New immunotherapies and molecular targeted therapies may improve the dismal survival outcomes in patients with metastatic ESCC.

Synthesis of Fluorescent Probes Targeting Tumor-Suppressor Protein FHIT and Identification of Apoptosis-Inducing FHIT Inhibitors

For the early diagnosis of cancer, leading to a better chance of full recovery, marker genes whose expression is already altered in precancerous lesions are desirable, and the tumor-suppressor gene FHIT is one candidate. The gene product, FHIT protein, has a unique dinucleoside triphosphate hydrolase (AP₃Aase) activity, and in this study, we designed and synthesized a series of FHIT fluorescent probes utilizing this activity. We optimized the probe structure for high and specific reactivity with FHIT and applied the optimized probe in a screening assay for FHIT inhibitors. Screening of a compound library with this assay identified several hits. Structural development of a hit compound afforded potent FHIT inhibitors. These inhibitors induce apoptosis in FHIT-expressing cancers via caspase activation. Our results support the idea that FHIT binders, no matter whether inhibitors or agonists of AP₃Aase activity, might be promising anticancer agents.

FHITlow /pHER2high signature in non-small cell lung cancer is predictive of anti-HER2 molecule efficacy

Despite its efficacy in solid tumours, in particular HER2⁺ breast cancer, HER2-targeted therapy has given rise to disappointing results in non-small cell lung cancer (NSCLC). With the aim of refining the target population for anti-HER2 therapies in NSCLC, we investigated the relationships between HER2 and the tumour suppressor fragile histidine triad (FHIT) in lung tumour cells. First, we observed a negative correlation between FHIT expression and the activated form of HER2 (pHER2) in NSCLC samples and in lung tumour cell lines. Moreover, the silencing or overexpression of FHIT in lung cell lines led to an increase or decrease of HER2 activity, respectively. We also demonstrated that two anti-HER2 drugs, irbinitinib and trastuzumab, restore a more epithelial phenotype and counteract cell invasiveness and growth of FHIT-silenced tumour cell lines. Finally, we showed that the FHIT^low /pHER2^high phenotype predicts sensitivity to an anti-HER2 therapy in primary tumour cells from NSCLC patients. Our results show that FHIT regulates the activity of HER2 in lung tumour cells and that FHIT-inactivated tumour cells are sensitive to HER2 inhibitors. A new subclass of patients with NSCLC may be eligible for an anti-HER2 therapy. © 2020 Pathological Society of Great Britain and Ireland. Published by John Wiley & Sons, Ltd.

Translatable gene therapy for lung cancer using Crispr CAS9-an exploratory review

Gene therapy using CRISPR Cas9 technique is rapidly gaining popularity among the scientific community primarily because of its versatility, cost-effectiveness, and high efficacy. While the laboratory-based experiments and findings making use of CRISPR as a gene editing tool are available in ample amounts, the question arises that how much of these findings are actually translatable into measures helping in combating particular disease conditions. In this review, we highlight the important studies and findings done till now in the perspective of lung cancer with an in-depth analysis of various clinical trials associated with the use of CRISPR Cas9 technology in the field of cancer research.

[Phenotypical plasticity and targeted therapies in non-small cell lung carcinomas]

Lung cancer is the most diagnosed and deathly type of cancer worldwide. It has a poor prognosis because of a late diagnosis, high metastatic potential and resistance to conventional therapies. Since the 2000s, the emergence of targeted therapies has improved patients' outcomes. However, these therapies concern only a small proportion of patients, selected by the presence of molecular biomarkers that indicate the targeting relevance. Here, we discuss the possibility that new phenotypical biomarkers could be predictive factors for targeted therapies in lung cancer.

FHIT, a Novel Modifier Gene in Pulmonary Arterial Hypertension

RATIONALE

Pulmonary arterial hypertension (PAH) is characterized by progressive narrowing of pulmonary arteries, resulting in right heart failure and death. BMPR2 (bone morphogenetic protein receptor type 2) mutations account for most familial PAH forms whereas reduced BMPR2 is present in many idiopathic PAH forms, suggesting dysfunctional BMPR2 signaling to be a key feature of PAH. Modulating BMPR2 signaling is therapeutically promising, yet how BMPR2 is downregulated in PAH is unclear.

OBJECTIVES

We intended to identify and pharmaceutically target BMPR2 modifier genes to improve PAH.

METHODS

We combined siRNA high-throughput screening of >20,000 genes with a multicohort analysis of publicly available PAH RNA expression data to identify clinically relevant BMPR2 modifiers. After confirming gene dysregulation in tissue from patients with PAH, we determined the functional roles of BMPR2 modifiers in vitro and tested the repurposed drug enzastaurin for its propensity to improve experimental pulmonary hypertension (PH).

MEASUREMENTS AND MAIN RESULTS

We discovered FHIT (fragile histidine triad) as a novel BMPR2 modifier. BMPR2 and FHIT expression were reduced in patients with PAH. FHIT reductions were associated with endothelial and smooth muscle cell dysfunction, rescued by enzastaurin through a dual mechanism: upregulation of FHIT as well as miR17-5 repression. Fhit-/- mice had exaggerated hypoxic PH and failed to recover in normoxia. Enzastaurin reversed PH in the Sugen5416/hypoxia/normoxia rat model, by improving right ventricular systolic pressure, right ventricular hypertrophy, cardiac fibrosis, and vascular remodeling.

CONCLUSIONS

This study highlights the importance of the novel BMPR2 modifier FHIT in PH and the clinical value of the repurposed drug enzastaurin as a potential novel therapeutic strategy to improve PAH.

Fhit, a tumor suppressor protein, induces autophagy via 14-3-3τ in non-small cell lung cancer cells

Inactivation of the fragile histidine triad (Fhit) gene has been reported in the majority of human cancers, particularly in lung cancer. The role of Fhit as a tumor suppressor gene has been well documented, and restoration of Fhit expression suppresses tumorigenicity in tumor cell lines and in mouse models by inducing apoptosis and inhibiting proliferation of tumor cells. Autophagy is a catabolic pathway, whereby cytoplasmic proteins and organelles are sequestered in vacuoles and delivered to lysosomes for degradation and recycling. Although autophagy is necessary for cell survival under stress conditions, recent studies have shown that autophagy can also promote cell death. Due to the fact that both autophagy induction and Fhit expression are commonly associated with nutrient starvation, we hypothesized that Fhit expression may be related to autophagy induction. In the present study, we assessed whether Fhit overexpression by gene transfer induces autophagy in Fhit-deficient non-small cell lung cancer (NSCLC) cells. The results of our study indicate that Fhit protein induces autophagy in NSCLC cells, and that this autophagy prevents apoptotic cell death in vivo and in vitro in a 14-3-3τ protein-dependent manner. To the best of our knowledge, this is the first report to describe Fhit-induced autophagy. Suppressing autophagy might be a promising therapeutic option to enhance the efficacy of Fhit gene therapy in NSCLC.

Mutation Analysis of the FHIT Gene in Bronchoscopic Specimens from Patients with Suspected Lung Cancer

Aims and Background

Lung cancer is a leading cause of cancer death worldwide. However, despite recent advances in molecular biology that have revealed various genetic changes in lung cancer, the prognostic outcome of lung cancer patients has improved only minimally. This situation has changed fundamentally with the identification of molecular abnormalities that are characteristic of premalignant changes, such as changes in tumor suppressor genes, loss of heterozygosity at crucial sites, and activation of oncogenes. Inactivation of the tumor suppressor gene Fragile Histidine Triad (FHIT) is a frequent genetic change in lung cancer. The aim of this study was to identify FHIT gene alterations in bronchoscopy specimens of patients with suspected lung cancer and to determine the molecular relevance, if any, of FHIT alterations in the development of cancer.

Patients and Methods

Sixty-two patients with suspected lung tumors were screened for variations within exons 5-9 of the FHIT gene using intronic primer pairs and single-strand conformation polymorphism and sequencing analysis.

Results

FHIT gene alterations were detected in 27 out of 62 bronchoscopic specimens (43.54%). All of these alterations were identified as T to A alteration at position IVS8-17. This intronic variant also was identified in approximately half of control cases (45%).

Conclusions

Our findings showed that the FHIT IVS8-17 T to A alteration identified in bronchoscopy specimens from patients with clinically suspected lung cancer is a polymorphism found in the Turkish population. We think that this polymorphism does not affect gene function because it is located in the intron portion of the gene and is present in many cancer patients as well as healthy subjects. We suggest that the FHIT gene may be turned off in lung carcinogenesis via other genetic or epigenetic mechanisms rather than mutations.

HPV, KRAS mutations, alcohol consumption and tobacco smoking effects on esophageal squamous-cell carcinoma carcinogenesis

Esophageal squamous-cell carcinoma (ESCC) is an invasive neoplastic disease generally associated with poor survival rates. The incidence of ESCC is characterized by marked geographic variation, with highest rates noted in developing Southeastern African, Central and Eastern Asian countries. In the developed Western European and North American regions where there is a low disease incidence, heavy alcohol and cigarette consumption constitute major risk factors. The toxic effects of both these risk factors cause chronic irritation and inflammation of the esophageal mucosa, while at the cellular level they further confer mutagenic effects by the activation of oncogenes (e.g., RAS mutations), inhibition of tumor-suppressor genes, and profound DNA damage. Viral infections, particularly with human papillomavirus, may activate specific antiapoptotic, proliferative and malignant cellular responses that may be intensified in combination with the effects of alcohol and tobacco. In countries with a high ESCC incidence, low socioeconomic status and an inadequate diet of poorly preserved food are combined with basic nutritional deficiencies and inadequate medical treatment. These conditions are favorable to the above-mentioned risk factors implicated in ESCC development, which may be present and/or habitually used in certain populations. New perspectives in epidemiological studies of ESCC development and its risk factors allow genome-wide research involving specific environments and habits. Such research should consist of adequately large and representative samples, should use newly designed informative genetic markers, and apply genomic variation analysis of the functional transcripts involved in malignant cell cycle regulation and neoplastic transformation in the multi-step process of ESCC carcinogenesis.

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.

Association of activated Gαq to the tumor suppressor Fhit is enhanced by phospholipase Cβ

BACKGROUND

G proteins are known to modulate various growth signals and are implicated in the regulation of tumorigenesis. The tumor suppressor Fhit is a newly identified interaction partner of Gq proteins that typically stimulate the phospholipase C pathway. Activated Gαq subunits have been shown to interact directly with Fhit, up-regulate Fhit expression and enhance its suppressive effect on cell growth and migration. Other signaling molecules may be involved in modulating Gαq/Fhit interaction.

METHODS

To test the relationship of PLCβ with the interaction between Gαq and Fhit, co-immunoprecipication assay was performed on HEK293 cells co-transfected with different combinations of Flag-Fhit, Gα16, Gα16QL, pcDNA3 vector, and PLCβ isoforms. Possible associations of Fhit with other effectors of Gαq were also demonstrated by co-immunoprecipitation. The regions of Gαq for Fhit interaction and PLCβ stimulation were further evaluated by inositol phosphates accumulation assay using a series of Gα16/z chimeras with discrete regions of Gα16 replaced by those of Gαz.

RESULTS

PLCβ1, 2 and 3 interacted with Fhit regardless of the expression of Gαq. Expression of PLCβ increased the affinities of Fhit for both wild-type and activated Gαq. Swapping of the Fhit-interacting α2-β4 region of Gαq with Gαi eliminated the association of Gαq with Fhit without affecting the ability of the mutant to stimulate PLCβ. Other effectors of Gαq including RGS2 and p63RhoGEF were unable to interact with Fhit.

CONCLUSIONS

PLCβ may participate in the regulation of Fhit by Gq in a unique way. PLCβ interacts with Fhit and increases the interaction between Gαq and Fhit. The Gαq/PLCβ/Fhit complex formation points to a novel signaling pathway that may negatively regulate tumor cell growth.

CRISPR/Cas9: molecular tool for gene therapy to target genome and epigenome in the treatment of lung cancer

Although varied drugs and therapies have been developed for lung cancer treatment, in the past 5 years overall survival rates have not improved much. It has also been reported that lung cancer is diagnosed in most of the patients when it is already in the advanced stages with heterogeneous tumors where single therapy is mostly ineffective. A combination of therapies are being administered and specific genes in specific tissues are targeted while protecting normal cell, but most of the therapies face drawbacks for the development of resistance against them and tumor progression. Therefore, therapeutic implications for various therapies need to be complemented by divergent strategies. This review frames utilization of CRISPR/Cas9 for molecular targeted gene therapy leading to long-term repression and activation or inhibition of molecular targets linked to lung cancer, avoiding the cycles of therapy.

Expression characteristics of FHIT, p53, BRCA2 and MLH1 in families with a history of oesophageal cancer in a region with a high incidence of oesophageal cancer

The aim of the present study was to determine the changes to the expression levels of fragile histidine triad (FHIT), breast cancer type 2 susceptibility protein (BRCA2), MutL homolog 1 (MLH1) and tumour protein 53 (p53) exhibited by families with a history of oesophageal cancer in a region that has a high incidence of oesophageal cancer, and to determine the association of these changes with the cancer history of the families. Immunohistochemistry was used to detect the protein expression of FHIT, p53, BRCA2, and MLH1 in the excised specimens of cancer tissues from 74 oesophageal cancer patients (positive family history of oesophageal cancer [OCFH +], n=33; negative family history of oesophageal cancer [OCFH -], n=41) from a region with a high incidence of oesophageal cancer. The positive expression rates of FHIT (61%; 45/74), BRCA2 (50%; 37/74) and MLH1 (27%; 9/33) in the oesophageal cancer tissues were significantly lower than those in the healthy tissues adjacent to the cancer (97% [29/30], 87% [26/30] and 73% [25/41], respectively). A significant difference was identified between the positive expression rates (P<0.01). However, FHIT, p53, BRCA2 and MLH1 expression demonstrated no significant affect on clinicopathological changes, such as oesophageal cancerous tissue differentiation, the degree of infiltration and cancer cell metastasis. The FHIT, BRCA2 and MLH1 expression levels were identified to be significantly lower in the cancer tissues from OCFH + patients. This result indicates that the expression levels of FHIT, BRCA2, and MLH1 are important molecular indices of genetic susceptibility to oesophageal cancer.

Human papillomavirus and non-small cell lung cancer

Lung cancer is the most common cause of cancer-related deaths in the world, causing more than one million deaths worldwide each year. Human papillomavirus (HPV) are small non-enveloped DNA viruses that infect squamous epithelial cells. Relevant studies have reported lung cancer-related HPV infection rates that fluctuate between 10% and 80%, depending on the various research methods and geographical factors. Various scholars gathered statistics from global research reports and found that 22.4% of the patients with lung cancer presented with an HPV infection, which suggested that HPV infection may relate to the tumorigenesis of non-small cell lung cancer. This article will review the history and discovery of HPV, the correlation between HPV and lung cancer development, and carcinogenesis caused by HPV regulatory genes, such as p53, p21, p16INK4a, and genes related to hypermethylation and genome instability in lung cancer patients with HPV infection. In addition, because studies have highlighted the difference in clinical prognosis for HPV-positive and HPV-negative patients, articles demonstrating the correlation between HPV infection and prognosis for lung cancer patients will be reviewed.

Activation of Gαq subunits up-regulates the expression of the tumor suppressor Fhit

The tumor suppressor Fhit protein is defective or absent in many tumor cells due to methylation, mutation or deletion of the FHIT gene. Despite numerous attempts to unravel the functions of Fhit, the mechanisms by which the function and expression of Fhit are regulated remain poorly understood. We have recently shown that activated Gαq subunits interact directly with Fhit and enhance its inhibitory effect on cell growth. Here we investigated the regulation of Fhit expression by Gq. Our results showed that Fhit was up-regulated specifically by activating Gα subunits of the Gq subfamily but not by those of the other G protein subfamilies. This up-regulation effect was mediated by a PKC/MEK pathway independent of Src-mediated Fhit Tyr(114) phosphorylation. We further demonstrated that elevated Fhit expression was due to the specific regulation of Fhit protein synthesis in the ribosome by activated Gαq, where the regulations of cap-dependent protein synthesis were apparently not required. Moreover, we showed that activated Gαq could increase cell-cell adhesion through Fhit. These findings provide a possible handle to modulate the level of the Fhit tumor suppressor by manipulating the activity of Gq-coupled receptors.

Activation state-dependent interaction between Gαq subunits and the Fhit tumor suppressor

Background

The FHIT tumor suppressor gene is arguably the most commonly altered gene in cancer since it is inactivated in about 60% of human tumors. The Fhit protein is a member of the ubiquitous histidine triad proteins which hydrolyze dinucleoside polyphosphates such as Ap₃A. Despite the fact that Fhit functions as a tumor suppressor, the pathway through which Fhit inhibits growth of cancer cells remains largely unknown. Phosphorylation by Src tyrosine kinases provides a linkage between Fhit and growth factor signaling. Since many G proteins can regulate cell proliferation through multiple signaling components including Src, we explored the relationship between Gα subunits and Fhit.

Results

Several members of the Gα_q subfamily (Gα₁₆, Gα₁₄, and Gα_q) were found to co-immunoprecipitate with Fhit in their GTP-bound active state in HEK293 cells. The binding of activated Gα_q members to Fhit appeared to be direct and was detectable in native DLD-1 colon carcinoma cells. The use of Gα_16/z chimeras further enabled the mapping of the Fhit-interacting domain to the α2-β4 region of Gα₁₆. However, Gα_q/Fhit did not affect either Ap₃A binding and hydrolysis by Fhit, or the ability of Gα_q/16 to regulate downstream effectors including phospholipase Cβ, Ras, ERK, STAT3, and IKK. Functional mutants of Fhit including the H96D, Y114F, L25W and L25W/I10W showed comparable abilities to associate with Gα_q. Despite the lack of functional regulation of G_q signaling by Fhit, stimulation of G_q-coupled receptors in HEK293 and H1299 cells stably overexpressing Fhit led to reduced cell proliferation, as opposed to an enhanced cell proliferation typically seen with parental cells.

Conclusions

Activated Gα_q members interact with Fhit through their α2-β4 region which may result in enhancement of the growth inhibitory effect of Fhit, thus providing a possible avenue for G protein-coupled receptors to modulate tumor suppression.

Serine, glycine and one-carbon units: cancer metabolism in full circle

One-carbon metabolism involving the folate and methionine cycles integrates nutritional status from amino acids, glucose and vitamins, and generates diverse outputs, such as the biosynthesis of lipids, nucleotides and proteins, the maintenance of redox status and the substrates for methylation reactions. Long considered a 'housekeeping' process, this pathway has recently been shown to have additional complexity. Genetic and functional evidence suggests that hyperactivation of this pathway is a driver of oncogenesis and establishes a link to cellular epigenetic status. Given the wealth of clinically available agents that target one-carbon metabolism, these new findings could present opportunities for translation into precision cancer medicine.

Genetic expression profiles of adult and pediatric ependymomas: molecular pathways, prognostic indicators, and therapeutic targets

Ependymomas are tumors that can present within either the intracranial or spinal regions. While 90% of all pediatric ependymomas are intracranial, spinal cord ependymomas are more commonly found in patients 20-40 years old. Treatment for spinal lesions has achieved local control rates up to 100% following gross total resection, while pediatric intracranial tumors have 40-60% mortality. Given the inability to effectively treat ependymomas with current standard practices, researchers have focused their efforts on evaluating chromosomal alterations, genetic expression profiles, epigenetic events, and molecular pathways. While these studies have provided critical insight into the potential mechanisms underlying ependymoma pathogenesis, understanding of the intricate interplay between the various pathways involved in tumor initiation, development, and progression will require deeper investigation. However, several potential prognostic markers and therapeutic targets have been identified, providing key areas of focus for future research. The utilization of unique genetic expression profiles based upon patient age, tumor location, tumor grade, and subtype has revealed a multitude of findings warranting further study. Inspection of various molecular pathways associated with ependymomas may establish the foundation for developing novel therapies capable of achieving significant clinical improvements with individualized regimens specifically designed for personalized treatment strategies.

Genomic copy number alterations in clear cell renal carcinoma: associations with case characteristics and mechanisms of VHL gene inactivation

Array comparative genomic hybridization was used to identify copy number alterations in clear cell renal cell carcinoma (ccRCC) patient tumors to identify associations with patient/clinical characteristics. Of 763 ccRCC patients, 412 (54%) provided frozen biopsies. Clones were analyzed for significant copy number differences, adjusting for multiple comparisons and covariates in multivariate analyses. Frequent alterations included losses on: 3p (92.2%), 14q (46.8%), 8p (38.1%), 4q (35.4%), 9p (32.3%), 9q (31.8%), 6q (30.8%), 3q (29.4%), 10q (25.7%), 13q (24.5%), 1p (23.5%) and gains on 5q (60.2%), 7q (39.6%), 7p (30.6%), 5p (26.5%), 20q (25.5%), 12q (24.8%), 12p (22.8%). Stage and grade were associated with 1p, 9p, 9q, 13q and 14q loss and 12q gain. Males had more alterations compared with females, independent of stage and grade. Significant differences in the number/types of alterations were observed by family cancer history, age at diagnosis and smoking status. Von Hippel–Lindau (VHL) gene inactivation was associated with 3p loss (P<E-05), and these cases had fewer alterations than wild-type cases. The fragile site flanking the FHIT locus (3p14.2) represented a unique breakpoint among VHL hypermethylated cases, compared with wild-type cases and those with sequence changes. This is the first study of its size to investigate copy number alterations among cases with extensive patient, clinical/risk factor information. Patients characterized by VHL wild-type gene status (vs sequence alterations) and male (vs female) cases had more copy number alterations regardless of diagnostic stage and grade, which could relate to poor prognosis.

Identification of putative cancer genes through data integration and comparative genomics between plants and humans

Coordination of cell division with growth and development is essential for the survival of organisms. Mistakes made during replication of genetic material can result in cell death, growth defects, or cancer. Because of the essential role of the molecular machinery that controls DNA replication and mitosis during development, its high degree of conservation among organisms is not surprising. Mammalian cell cycle genes have orthologues in plants, and vice versa. However, besides the many known and characterized proliferation genes, still undiscovered regulatory genes are expected to exist with conserved functions in plants and humans. Starting from genome-wide Arabidopsis thaliana microarray data, an integrative strategy based on coexpression, functional enrichment analysis, and cis-regulatory element annotation was combined with a comparative genomics approach between plants and humans to detect conserved cell cycle genes involved in DNA replication and/or DNA repair. With this systemic strategy, a set of 339 genes was identified as potentially conserved proliferation genes. Experimental analysis confirmed that 20 out of 40 selected genes had an impact on plant cell proliferation; likewise, an evolutionarily conserved role in cell division was corroborated for two human orthologues. Moreover, association analysis integrating Homo sapiens gene expression data with clinical information revealed that, for 45 genes, altered transcript levels and relapse risk clearly correlated. Our results illustrate how a systematic exploration of the A. thaliana genome can contribute to the experimental identification of new cell cycle regulators that might represent novel oncogenes or/and tumor suppressors.

Promoter methylation of tumor suppressor genes in esophageal squamous cell carcinoma

Esophageal squamous cell carcinoma (ESCC) is a prevalent and fatal cancer in China and other Asian countries. Epigenetic silencing of key tumor suppressor genes (TSGs) is critical to ESCC initiation and progression. Recently, many novel TSGs silenced by promoter methylation have been identified in ESCC, and these genes further serve as potential tumor markers for high-risk group stratification, early detection, and prognosis prediction. This review summarizes recent discoveries on aberrant promoter methylation of TSGs in ESCC, providing better understanding of the role of disrupted epigenetic regulation in tumorigenesis and insight into diagnostic and prognostic biomarkers for this malignancy.

Comparative analysis of algorithms for integration of copy number and expression data

Chromosomal instability is a hallmark of cancer, and genes that display abnormal expression in aberrant chromosomal regions are likely to be key players in tumor progression. Identifying such driver genes reliably requires computational methods that can integrate genome-scale data from several sources. We compared the performance of ten algorithms that integrate copy-number and transcriptomics data from 15 head and neck squamous cell carcinoma cell lines, 129 lung squamous cell carcinoma primary tumors and simulated data. Our results revealed clear differences between the methods in terms of sensitivity and specificity as well as in their performance in small and large sample sizes. Results of the comparison are available at http://csbi.ltdk.helsinki.fi/cn2gealgo/.

Evaluation of influence of Ap4A analogues on Fhit-positive HEK293T cells; cytotoxicity and ability to induce apoptosis

Fragile histidine triad (Fhit) protein encoded by tumour suppressor FHIT gene is a proapoptotic protein with diadenosine polyphosphate (Ap(n)A, n=2-6) hydrolase activity. It has been hypothesised that formation of Fhit-substrate complex results in an apoptosis initiation signal while subsequent hydrolysis of Ap(n)A terminates this action. A series of Ap(n)A analogues have been identified in vitro as strong Fhit ligands [Varnum, J. M.; Baraniak, J.; Kaczmarek, R.; Stec, W. J.; Brenner, C. BMC Chem. Biol.2001, 1, 3]. We assumed that in Fhit-positive cells these compounds might preferentially bind to Fhit and inhibit its hydrolytic activity what would prolong the lifetime of apoptosis initiation signalling complex. Therefore, several Fhit inhibitors were tested for their cytotoxicity and ability to induce apoptosis in Fhit-positive HEK293T cells. These experiments have shown that Ap(4)A analogue, containing a glycerol residue instead of the central pyrophosphate and two terminal phosphorothioates [A(PS)-CH(2)CH(OH)CH(2)-(PS)A (1)], is the most cytotoxic among test compounds (IC(50)=17.5±4.2 μM) and triggers caspase-dependent cell apoptosis. The Fhit-negative HEK293T cells (in which Fhit was silenced by RNAi) were not sensitive to compound 1. These results indicate that the Ap(4)A analogue 1 induces Fhit-dependent apoptosis and therefore, it can be considered as a drug candidate for anticancer therapy in Fhit-positive cancer cells and in Fhit-negative cancer cells, in which re-expression of Fhit was accomplished by gene therapy.

High resolution analysis of follicular lymphoma genomes reveals somatic recurrent sites of copy-neutral loss of heterozygosity and copy number alterations that target single genes

A multiplatform approach, including conventional cytogenetic techniques, BAC array comparative genomic hybridization, and Affymetrix 500K SNP arrays, was applied to the study of the tumor genomes of 25 follicular lymphoma biopsy samples with paired normal DNA samples to characterize balanced translocations, copy number imbalances, and copy-neutral loss of heterozygosity (cnLOH). In addition to the t(14;18), eight unique balanced translocations were found. Commonly reported FL-associated copy number regions were revealed including losses of 1p32-36, 6q, and 10q, and gains of 1q, 6p, 7, 12, 18, and X. The most frequent regions affected by copy-neutral loss of heterozygosity were 1p36.33 (28%), 6p21.3 (20%), 12q21.2-q24.33 (16%), and 16p13.3 (24%). We also identified by SNP analysis, 45 aberrant regions that each affected one gene, including CDKN2A, CDKN2B, FHIT, KIT, PEX14, and PTPRD, which were associated with canonical pathways involved in tumor development. This study illustrates the power of using complementary high-resolution platforms on paired tumor/normal specimens and computational analysis to provide potential insights into the significance of single-gene somatic aberrations in FL tumorigenesis.

Immunohistochemical FHIT expression still exists in early lesions of basal cell carcinoma

In this study, we evaluated the expression of Fragile Histidine Triad (FHIT) in basal cell carcinoma (BCC). The FHIT locus was found to be altered in numerous types of cancer [6,7,18,20,22,25,26]. However, we found only one study dealing with FHIT expression in BCC [11]. In our study, we used immunohistochemical methods for the evaluation of FHIT expression in tissue samples of 42 BCC cases. The control group was formed by intradermal melanocytic nevi (IMN). Ki-67 labeling index was used to compare cellular proliferation of BCC with internal and external controls. The study group was further separated into two subgroups, according to the intensity of FHIT staining. The Ki-67 indexes of these subgroups were also compared with each other. As a primary result, there was no significant decrease in FHIT expression in early lesions of BCC. As a second finding, there was no correlation between the intensity of FHIT staining and Ki-67 labeling index. As a third finding, there was no difference in Ki-67 labeling index between early lesions of BCC and non-neoplastic epidermis. The results were unexpected, since FHIT expression has been reported to be lost in an above mentioned study [11]. We concluded that FHIT expression remains to be positive, at least in early lesions of BCC.

Overexpression of p73 as a tissue marker for high-risk gastritis

PURPOSE

Histologic assessment of high-risk gastritis for the development of gastric cancer is not well defined. The identification of tissue markers together with the integration of histologic features will be required for this assessment.

EXPERIMENTAL DESIGN

Matched tumor/nontumor adjacent mucosa (NTAM) of 91 early gastric cancer and 148 chronic gastritis cases were evaluated for histologic characteristics (atrophy, intestinal metaplasia, chronic inflammation, polymorphonuclear infiltration, and Helicobacter pylori) by the Sydney System. Atrophy risk assessment was also evaluated by the Operative Link on Gastritis Assessment (OLGA) staging system. Eight tissue markers (BRCA1, HSP90, STAT1, FHIT, EGFR, p73, p53, p16INK4a) and EBV were also evaluated by tissue microarray/immunohistochemistry/in situ hybridization platform. Data were analyzed by contingency tables (2 x 2) using Fisher's exact two-tailed test (P < 0.001) and integrated by Significance Analysis of Microarrays (SAM) and clustering analysis.

RESULTS

Histologically, NTAM have severe intestinal metaplasia/chronic inflammation and severe atrophy assessed by Sydney and OLGA staging systems. H. pylori infection was similar in both groups, and EBV was found only in 5.5% of the tumor samples. Overexpression of p73 was higher in NTAM (50.5%) than in chronic gastritis (10.8%; P < 0.0001). Integration of histologic features and tissue markers showed that overexpression of p73, severe atrophy, and OLGA stage 4 were the most relevant features in NTAM. Clustering analysis correctly assigned NTAM and control cases (P < 0.0001).

CONCLUSIONS

Overexpression of p73 should be considered for the assessment of high-risk chronic gastritis. SAM allows the integration of histology and tissue markers for this assessment.

Alcohol drinking, cigarette smoking, and the development of squamous cell carcinoma of the esophagus: molecular mechanisms of carcinogenesis

Esophageal cancer is the eighth most common incident cancer in the world and ranks sixth among all cancers in mortality. Esophageal cancers are classified into two histological types; esophageal squamous cell carcinoma (ESCC), and adenocarcinoma, and the incidences of these types show a striking variety of geographic distribution, possibly reflecting differences in exposure to specific environmental factors. Both alcohol consumption and cigarette smoking are major risk factors for the development of ESCC. Acetaldehyde is the most toxic ethanol metabolite in alcohol-associated carcinogenesis, while ethanol itself stimulates carcinogenesis by inhibiting DNA methylation and by interacting with retinoid metabolism. Cigarette smoke contains more than 60 carcinogens and there are strong links between some of these carcinogens and various smoking-induced cancers; these mechanisms are well established. Synergistic effects of cigarette smoking and alcohol consumption are also observed in carcinogenesis of the upper aerodigestive tract. Of note, intensive molecular biological studies have revealed the molecular mechanisms involved in the development of ESCC, including genetic and epigenetic alterations. However, a wide range of molecular changes is associated with ESCC, possibly because the esophagus is exposed to many kinds of carcinogens including alcohol and cigarette smoke, and it remains unclear which alterations are the most critical for esophageal carcinogenesis. This brief review summarizes the general mechanisms of alcohol- and smoking-induced carcinogenesis and then discusses the mechanisms of the development of ESCC, with special attention to alcohol consumption and cigarette smoking.

Chromosomal imbalances are uncommon in chagasic megaesophagus

BACKGROUND

Chagas' disease is a human tropical parasitic illness and a subset of the chronic patients develop megaesophagus or megacolon. The esophagus dilation is known as chagasic megaesophagus (CM) and one of the severe late consequences of CM is the increased risk for esophageal carcinoma (ESCC). Based on the association between CM and ESCC, we investigated whether genes frequently showing unbalanced copy numbers in ESCC were altered in CM by fluorescence in situ (FISH) technology.

METHODS

A total of 50 formalin-fixed, paraffin-embedded esophageal mucosa specimens (40 from Chagas megaesophagus-CM, and 10 normal esophageal mucosa-NM) were analyzed. DNA FISH probes were tested for FHIT, TP63, PIK3CA, EGFR, FGFR1, MYC, CDKN2A, YES1 and NCOA3 genes, and centromeric sequences from chromosomes 3, 7 and 9.

RESULTS

No differences between superficial and basal layers of the epithelial mucosa were found, except for loss of copy number of EGFR in the esophageal basal layer of CM group. Mean copy number of CDKN2A and CEP9 and frequency of nuclei with loss of PIK3CA were significantly different in the CM group compared with normal mucosa and marginal levels of deletions in TP63, FHIT, PIK3CA, EGFR, CDKN2A, YES and gains at PIK3CA, TP63, FGFR1, MYC, CDNK2A and NCOA3 were detected in few CM cases, mainly with dilation grades III and IV. All changes occurred at very low levels.

CONCLUSIONS

Genomic imbalances common in esophageal carcinomas are not present in chagasic megaesophagus suggesting that these features will not be effective markers for risk assessment of ESCC in patients with chagasic megaesophagus.

Fhit regulates invasion of lung tumor cells

In many types of cancers, the fragile histidine triad (Fhit) gene is frequently targeted by genomic alterations leading to a decrease or loss of gene and protein expression. Fhit has been described as a tumor suppressor gene because of its ability to induce apoptosis and to inhibit proliferation of tumor cells. Moreover, several studies have shown a correlation between the lack of Fhit expression and tumor aggressiveness, thus suggesting that Fhit could be involved in tumor progression. In this study, we explored the potential role of Fhit during tumor cell invasion. We first showed that a low Fhit expression is associated with in vivo and in vitro invasiveness of tumor cells. Then, we showed that Fhit overexpression in Fhit-negative highly invasive NCI-H1299 cells by transfection of Fhit cDNA and Fhit inhibition in Fhit-positive poorly invasive HBE4-E6/E7 cells by transfection of Fhit small interfering RNA induce, respectively, a decrease and an increase in migratory/invasive capacities. These changes in cell behavior were associated with a reorganization of tight and adherens junction molecules and a regulation of matrix metalloproteinase and vimentin expression. These results show that Fhit controls the invasive phenotype of lung tumor cells by regulating the expression of genes associated with epithelial-mesenchymal transition.

Helicobacter pylori infection and family history of gastric cancer decrease expression of FHIT tumor suppressor gene in gastric mucosa of dyspeptic patients

BACKGROUND

The expression of a fragile histidine triad (FHIT) protein is lost in stomach tumors. The study aimed at determining whether FHIT expression is affected by Helicobacter pylori infection, strain virulence (vacA and cagA genes) and histopathological changes in the gastric mucosa of patients with functional dyspepsia having first-degree relatives with gastric cancer.

MATERIALS AND METHODS

Eighty-eight never-smoking patients with functional dyspepsia were selected for the study, and 48 of them had first-degree relatives with gastric cancer. Bacterial DNA amplification was used to identify H. pylori colonization. The level of FHIT gene expression was determined by qRT-PCR (mRNA) and Western blot (FHIT protein) analyses.

RESULTS

For patients having first-degree relatives with gastric cancer FHIT expression was lower (mRNA by ca. 40-45% and protein by 30%) compared with the control patients (p < .05). H. pylori infection decreased the FHIT mRNA level by 10-35% and the protein level by 10-20%. Bacterial strain vacA(+)cagA(+) lowered FHIT mRNA by ca. 30-35% in the antrum samples of both groups and in corpus samples of patients with first-degree relatives with gastric cancer (p < .05). The FHIT mRNA level was twice as high in control H. pylori-negative patients with intestinal metaplasia, compared with those with non-atrophic gastritis.

CONCLUSIONS

The decreased FHIT gene expression associated with hereditary factors and with H. pylori infection, especially with vacA(+)cagA(+)-positive strains, may be related to gastric carcinoma development.

Enlightened protein: Fhit tumor suppressor protein structure and function and its role in the toxicity of protoporphyrin IX-mediated photodynamic reaction

The Fhit tumor suppressor protein possesses Ap(3)A (diadenosine triphosphate - ApppA) hydrolytic activity in vitro and its gene is found inactive in many pre-malignant states due to gene inactivation. For several years Fhit has been a widely investigated protein as its cellular function still remains largely unsolved. Fhit was shown to act as a molecular 'switch' of cell death via cascade operating on the influence of ATR-Chk1 pathway but also through the mitochondrial apoptotic pathway. Notably, Fhit was reported by our group to enhance the overall eradication effect of porphyrin-mediated photodynamic treatment (PDT). In this review the up-to-date findings on Fhit protein as a tumor suppressor and its role in PDT are presented.

Potential of DNMT and its Epigenetic Regulation for Lung Cancer Therapy

Lung cancer, the leading cause of mortality in both men and women in the United States, is largely diagnosed at its advanced stages that there are no effective therapeutic alternatives. Although tobacco smoking is the well established cause of lung cancer, the underlying mechanism for lung tumorigenesis remains poorly understood. An important event in tumor development appears to be the epigenetic alterations, especially the change of DNA methylation patterns, which induce the most tumor suppressor gene silence. In one scenario, DNA methyltransferase (DNMT) that is responsible for DNA methylation accounts for the major epigenetic maintenance and alternation. In another scenario, DNMT itself is regulated by the environment carcinogens (smoke), epigenetic and genetic information. DNMT not only plays a pivotal role in lung tumorigenesis, but also is a promising molecular bio-marker for early lung cancer diagnosis and therapy. Therefore the elucidation of the DNMT and its related epigenetic regulation in lung cancer is of great importance, which may expedite the overcome of lung cancer.

Identification of the HIT-45 protein from Trypanosoma brucei as an FHIT protein/dinucleoside triphosphatase: substrate specificity studies on the recombinant and endogenous proteins

A new member of the FHIT protein family, designated HIT-45, has been identified in the African trypanosome Trypanosoma brucei. Recombinant HIT-45 proteins were purified from trypanosomal and bacterial protein expression systems and analyzed for substrate specificity using various dinucleoside polyphosphates, including those that contain the 5'-mRNA cap, i.e., m(7)GMP. This enzyme exhibited typical dinucleoside triphosphatase activity (EC 3.6.1.29), having its highest specificity for diadenosine triphosphate (ApppA). However, the trypanosome enzyme contains a unique amino-terminal extension, and hydrolysis of cap dinucleotides with monomethylated guanosine or dimethylated guanosine always yielded m(7)GMP (or m(2,7)GMP) as one of the reaction products. Interestingly, m(7)Gpppm(3)(N6, N6, 2'O)A was preferred among the methylated substrates. This hypermethylated dinucleotide is unique to trypanosomes and may be an intermediate in the decay of cap 4, i.e., m(7)Gpppm(3)(N6, N6, 2'O)Apm(2'O)Apm(2'O)Cpm(2)(N3, 2'O)U, that occurs in these organisms.

Inverse correlation of aberrant expression of fragile histidine triad (FHIT) protein with cyclin D1 protein and prognosis in Chinese patients with cholangiocarcinoma

BACKGROUND

This is the first study to explore the relationship between the expression of fragile histidine triad, FHIT and cyclin D1 proteins, and the clinicopathological significance of the two proteins in Chinese patients with cholangiocarcinoma.

MATERIAL AND METHODS

Immunohistochemistry was used to study 53 cases of cholangiocarcinoma, 30 para-neoplastic and 20 normal bile ducts for their expression status of FHIT and cyclin D1 and then the results were analyzed with the patient's age, sex, tumour site, histological grade and clinical stage as well as overall median survival time.

RESULTS

Compared with the para-neoplastic and normal cholangiocytes, the expression of FHIT was obviously decreased (p=0.0001), whereas that of cyclin D1 was significantly increased (p=0.0001) in carcinoma cells. The expression of FHIT was found to be correlated with the histological grade (p=0.007) and the clinical stage (p=0.004), but not with age (p=0.776), sex (p=0.246) or tumour site (p=0.347). The expression of cyclin D1 was also showed statistically associated with the histological grade (p=0.043) and clinical stage (p=0.047), but not with age (p=0.965), sex (p=0.751) or tumour site (p=0.948). Further, the expression of FHIT was found to be inversely correlated with the expression of cyclin D1 (p=0.0001). The loss of expression of FHIT and the expression of cyclin D1 were significantly related to the cancers with shorter median survival time (p=0.0001, p=0.0081). The expression of FHIT was an independent prognostic factor (p=0.005).

DISCUSSION

The expression of FHIT may be inversely correlated with the expression of cyclin D1. It is suggested that the loss of FHIT protein and overexpression of cyclin D1 protein may play an important role in carcinogenesis and prognosis of cholangiocarcinoma.

Fhit tumor suppressor: guardian of the preneoplastic genome

Environmental agents induce intragenic alterations in the FRA3B/FHIT chromosome fragile site, resulting in fragile FHIT allele loss early in cancer development. Fhit knockout mice are predisposed to tumor development and Fhit gene therapy reduces tumor burden. Repair-deficient cancers are likely to be Fhit-deficient and Fhit-deficient cells show enhanced resistance to ultraviolet C, mitomycin C, camptothecin and oxidative stress-induced cell killing. Loss of Fhit leads to alterations in the DNA damage response checkpoint and contributes to DNA instability. Hsp60/Hsp10 are Fhit interactors, suggesting a direct role for Fhit in stress responses. Fhit also interacts with and stabilizes ferrodoxin reductase (Fdxr), a mitochondrial flavoprotein that transfers electrons from NADPH to cytochrome P450, suggesting a role for Fhit in the modulation of reactive oxygen species production and of genomic damage.

Detection of HPV-DNA, p53 alterations, and methylation in penile squamous cell carcinoma in Japanese men

Penile carcinoma is a rare disease, accordingly there are few studies on molecular changes, and these results also vary greatly. A total of 26 penile squamous cell carcinomas in Japanese men were studied with respect to HPV, p53 alterations, and methylation of gene promoter region. HPV-DNA was detected in three of 26 patients (11.5%). Overexpression of p53 was observed in 13 of 26 patients (50%), and p53 gene mutations were detected in four of 26 patients (15.4%). The frequency of methylation was as follows: DAPK, 26.9% (7/26); FHIT, 88.4% (23/26); MGMT, 19.2% (5/26); p14, 3.8% (1/26); p16, 23.1% (6/26); RAR-beta, 23.1% (6/26); RASSF1A, 11.5% (3/26); and RUNX3, 42.3% (11/26). As for correlation between HPV and p53 alterations, and methylation status, mutations of the p53 gene were detected only in HPV-negative patients, and methylation was more frequently found in HPV-negative than in HPV-positive patients. The present results suggest that the majority of penile squamous cell carcinomas in Japanese men are unrelated to HPV, and gene alterations accumulate more frequently in HPV-unrelated penile carcinomas.

Hypermethylation of the 5'CpG island of the FHIT gene in clear cell renal carcinomas

FHIT is a tumour suppressor gene which is frequently inactivated in different types of cancer. Both genetic (mutations, deletions, chromosomal rearrangements) and epigenetic (aberrant methylation of the 5'CpG island) alterations of the FHIT gene have been reported in various malignancies. Yet little is known about the mechanism of FHIT inactivation in clear cell renal carcinomas. Since genetic alterations were not frequently observed in DNA corresponding to the FHIT gene in renal tumours, to elucidate the mechanism of FHIT gene silencing we examined 22 paired samples of clear cell renal carcinoma and non-malignant renal tissue for the methylation of the FHIT 5'CpG island by methylation-specific PCR. Hypermethylation of the FHIT 5'CpG island was detected in 54.5% (12/22) of clear cell renal carcinomas. Bisulfite sequencing of the FHIT 5'CpG island confirmed the results obtained by methylation-specific PCR for selected samples. We showed here that expression of the FHIT gene is inversely correlated with hypermethylation of the FHIT 5'CpG island in the selected samples. Our results suggest that hypermethylation of the FHIT 5'CpG island may be responsible for inactivation of the FHIT gene in clear cell renal carcinomas.

Role of fragile histidine triad protein expression in pathogenesis of malignant pleural mesothelioma

AIM

To investigate the relationship of fragile histidine triad (FHIT) and Ki-67 expression with clinicopathological variables of patients with malignant pleural mesothelioma (MPM).

METHODS

Formalin-fixed, paraffin-embedded tissue sections of 30 asbestos induced MPM (epithelial and biphasic) patients were examined for FHIT and Ki-67 expression using immunohistochemical techniques and results were compared with clinicopathological variables.

RESULTS

Immunohistochemical study results were as follows: 12 (40%) cases showed low FHIT expression and 18 (60%) showed high expression. There was no significant relationship between FHIT and age, gender or histological subtypes (p > 0.05). Ki-67 expression was 'low' in 13 (43.3%) cases and 'high' in 17 (56.7%) cases. No correlation could be demonstrated between Ki-67 expression and age, gender or histological subtypes (p > 0.05). No significant association was observed between FHIT and Ki-67 expression in MPM.

CONCLUSION

The results support the role of FHIT as a tumour suppressor gene in asbestos induced MPM. There is no significant correlation between FHIT and cell proliferation marker expressions in malignant pleural mesothelioma. Therefore, it can be concluded that loss of FHIT does not interfere with tumour proliferation. This can be accepted as evidence for an early role of FHIT loss in carcinogenesis; however, it needs to be strengthened by further studies.