The molecular genetics of cervical carcinoma

Identification of novel methylation markers in cervical cancer using restriction landmark genomic scanning

Aberrant methylation of CpG islands in gene promoters often represents an early clonal event in carcinogenesis. Accordingly, defining methylation profiles may be useful for developing marker panels for early detection or predicting the risk of cancer precursors. To identify specific genes frequently methylated in cervical cancer, we conducted methylation profiling of 20 primary human cervical cancers using NotI-based restriction landmark genomic scanning (RLGS). Of 2,172 RLGS fragments analyzed (average, 1,753 CpG islands per patient), 186 RLGS fragments were lost in at least one tumor and 40 were lost in three or more. Methylation was identified in 19 (95%) of 20 tumor samples compared with normal DNA. Bisulfite sequencing was conducted to confirm RLGS results. Of the confirmed markers frequently methylated, we developed Methylight assays for two corresponding genes, nucleolar protein 4 (NOL4), and lipoma HMGIC fusion partner-like protein 4 (LHFPL4), which were methylated in 85% and 55% of cancers, respectively. Using these assays, we further confirmed frequent CpG island methylation in the original cancers and in another independent series of 15 cervical cancers. We also showed methylation at a reduced frequency in a set of carefully reviewed cytology specimens demonstrating cells exfoliated from cancer precursor lesions. In summary, we identified, for the first time, NOL4 and LHFPL4 as novel methylation targets specific for cervical cancer. Inclusion of NOL4 and LHFPL4 in evaluating methylation panels for early detection, risk prediction, and etiologic research on cervical cancer is warranted.

hGPR87 contributes to viability of human tumor cells

Emerging in vitro and in vivo data underline the crucial role of G-protein-coupled receptors (GPCRs) in tumorigenesis. Here, we report the contribution of hGPR87, a predicted member of the P2Y subfamily of GPCRs, to proliferation and survival of human tumor cell lines. hGPR87 mRNA transcript was found to be preferentially overexpressed in squamous cell carcinomas (SCCs) of different locations and in their lymph node metastases. Up-regulation of both, transcript and protein, was detected in samples of SCC of the lung, cervix, skin and head and neck (pharynx, larynx and epiglottis). In addition to the expression of hGPR87 in tumors which originate from stratified epithelia, we identified other hGPR87-positive tumor types including subsets of large cell and adenocarcinomas of the lung and transitional cell carcinomas of the urinary bladder. Loss of function studies using siRNA in human cancer cell lines lead to antiproliferative effects and induction of apoptosis. Like other known P2Y receptors, hGPR87 was found to be mainly located on the cell surface. The overexpression of hGPR87 preferentially in SCCs together with our functional data suggests a common molecular mechanism for SCC tumorigenesis and may provide a novel intervention site for mechanism-based antitumor therapies.

Type-dependent integration frequency of human papillomavirus genomes in cervical lesions

Chromosomal integration of high-risk human papillomavirus (HR-HPV) genomes is believed to represent a significant event in the pathogenesis of cervical cancer associated with progression from preneoplastic lesions to invasive carcinomas. This hypothesis is based on experimental data suggesting that integration-dependent disruption of HR-HPV E2 gene functions is important to achieve neoplastic transformation and on clinical data gathered by analyzing lesions induced by human papillomavirus (HPV) 16 and 18 that revealed integrated viral genome copies in the vast majority of cervical cancer cells. However, a substantial fraction of cervical cancers is associated with other HR-HPV types for which virtually no data concerning their integration status have been reported so far. Here, we compared integration frequencies of the five most common oncogenic HPV types (HPV16, 18, 31, 33, and 45) in a series of 835 cervical samples using a specific mRNA-based PCR assay (Amplification of Papillomavirus Oncogene Transcripts). Most precancerous lesions displayed exclusively episomal viral genomes, whereas 62% of the carcinomas had integrated viral genomes. However, the frequency of integrated HR-HPV genomes showed marked differences for individual HR-HPV types. HPV16, 18, and 45 were found substantially more often in the integrated state compared with HPV types 31 and 33. The analysis of the median age of patients with high-grade precancerous lesions and invasive cancers suggests that precancers induced by HPV types 18, 16, and 45 progress to invasive cervical cancer in substantially less time compared with precancers induced by HPV types 31 and 33. These findings suggest that integration of oncogenic HPV genomes in cervical lesions is a consequence rather than the cause of chromosomal instability induced by deregulated HR-HPV E6-E7 oncogene expression. Distinct HR-HPV types apparently provoke chromosomal instability in their host cells to a different extent than is reflected by their integration frequencies in advanced lesions and the time required for CIN 3 lesions to progress to invasive cancer.

Promoter hypermethylation of tumor suppressor genes in urine from patients with cervical neoplasia

We examined the feasibility of using detection of high-risk human papillomavirus (HPV) DNA in combination with the presence of aberrantly methylated genes (DAPK1, RARB, TWIST1, and CDH13) for urine-based cervical cancer screening. Urine samples from 129 Senegalese women, aged 35 years or older, 110 with (same day) biopsy-proven cervical neoplasia [cervical intraepithelial neoplasia grade 1 (CIN-1): n = 9; CIN-2-3/carcinoma in situ (CIS): n = 29; invasive cervical cancer (ICC): n = 72], and 19 without cervical neoplasia on biopsy were examined. Hypermethylation of at least one of the four genes identified 62% of ICC and 28% of CIN-2-3/CIS and was present in only 4% of CIN-1 or normal urines. High-risk HPV DNA was detected in urine in 70% of those with biopsy-proven ICC, 59% of those with CIN-2-3/CIS on biopsy, 44% of those with CIN-1 on biopsy, and only 11% of women negative for cervical neoplasia on biopsy. Urine-based detection of either high-risk HPV or hypermethylation of any of the four genes identified 84% of ICC, 64% of CIN-2-3/CIS, 44% of CIN-1, but only 19% of women negative for cervical neoplasia. The sensitivity for detection of CIN-2-3/CIS/ICC by high-risk HPV DNA or aberrant DNA methylation of four genes seems to be comparable to that of an exfoliated cervical cytology. This study shows the potential feasibility of using molecular markers detected in urine for cervical cancer screening.

Role of p53 in antioxidant defense of HPV-positive cervical carcinoma cells following H2O2 exposure

In HPV-positive cervical carcinoma cells, p53 protein is functionally antagonized by the E6 oncoprotein. We investigated a possible role of p53 in antioxidant defense of HPV-positive cervical cancer cell lines. We found that SiHa cells containing integrated HPV 16 had higher expression of p53 and exhibited the greatest resistant to H2O2-induced oxidative damage, compared with HeLa, CaSki and ME180 cell lines. Downregulation of p53 resulted in the inhibition of p53-regulated antioxidant enzymes and elevated intracellular ROS in SiHa cells. By contrast, the ROS level was not affected in HeLa, CaSki and ME180 cell lines after inhibition of the p53 protein. Under mild or severe H2O2-induced stress, p53-deficient SiHa cells exhibited much higher ROS levels than control SiHa cells. Furthermore, we analyzed cell viability and apoptosis after H2O2 treatment and found that p53 deficiency sensitized SiHa cells to H2O2 damage. Inhibition of p53 resulted in excessive oxidation of DNA; control SiHa cells exhibited a more rapid removal of 8-oxo-7,8-dihydro-2'-deoxyguanosine from DNA compared with p53-deficient SiHa cells exposed to the same level of H2O2 challenge. These data collectively show that endogenous p53 in SiHa cells has an antioxidant function and involves in the reinforcement of the antioxidant defense.

Deletions in chromosome 4 differentially associated with the development of cervical cancer: evidence of slit2 as a candidate tumor suppressor gene

The aim of this study was to locate the candidate tumor suppressor genes (TSGs) loci in the chromosomal 4p15-16, 4q22-23 and 4q34-35 regions associated with the development of uterine cervical carcinoma (CA-CX). Deletion mapping of the regions by microsatellite markers identified six discrete areas with high frequency of deletions, viz. 4p16.2 (D1: 40%), 4p15.31 (D2: 35-38%), 4p15.2 (D3: 37-40%), 4q22.2 (D4: 34%), 4q34.2-34.3 (D5: 37-59%) and 4q35.1 (D6: 40-50%). Significant correlation was noted among the deleted regions D1, D2 and D3. The deletions in D1, D2, D5 and D6 regions are suggested to be associated with the cervical intraepithelial neoplasia (CIN), and deletions in the D2, D3, D5 and D6 regions seems to be associated with progression of CA-CX. The deletions in the D2 and D6 regions showed significant prognostic implications (P = 0.001; 0.02). The expression of the candidate TSG SLIT2 mapped to D2 region gradually reduced from normal cervix uteri -->CIN --> CA-CX. SLIT2 promoter hypermethylation was seen in 28% CIN samples and significantly increased with tumor progression (P = 0.04). Significant correlation was seen between SLIT2 deletion and its promoter methylation (P = 0.001), indicating that both these phenomena could occur simultaneously to inactivate this gene. Immunohistochemical analysis showed reduced expression of SLIT2 in cervical lesions and CA-CX cell lines. Although no mutation was detected in the SLIT2 promoter region (-432 to + 55 bp), CC and AA haplotypes were seen in -227 and -195 positions, respectively. Thus, it indicates that inactivation of SLIT2-ROBO1 signaling pathway may have an important role in CA-CX development.

Arsenic trioxide (As2O3) reduces the invasive and metastatic properties of cervical cancer cells in vitro and in vivo

OBJECTIVES

Arsenic trioxide (As(2)O(3)) was found to induce apoptosis in certain types of cancer cells including acute promyelocytic leukemia, and recently in solid tumors. We have previously demonstrated that As(2)O(3) has a therapeutic effect on cervical cancer by apoptosis promotion in vitro and in vivo. Here we further our study on the role of arsenic trioxide in regulating invasive activity of cervical cancer cells in vitro and in vivo.

METHODS

The effects of As(2)O(3) on human cervical cancer cell lines (HeLa, SiHa, Caski) adhesion, migration and invasion were observed by means of cell adhesion test, cell migration test and cell invasion test. The effects of As(2)O(3) on p-IkappaB, MMP-2, E-cadherin, caveolin-1 and beta-catenin protein expressions of tumor cells were determined by Western blot. In addition, the effects of As(2)O(3) on NF-kappaB activity of tumor cells were analyzed by immunoblot in whole lysates, cytosol and nucleus, respectively. In animal experiments, cervical cancer cells TC-1 were injected into tail veins of C57BL/6 mice and then the mice were treated by intraperitoneal injection of different doses As(2)O(3). Lung weights and the foci on the surface of lungs were measured.

RESULTS

As(2)O(3) inhibited attachment of tumor cells to Fibronectin and Matrigel, reduced cell motility and inhibited tumor invasion potential. As(2)O(3) treatment also resulted in a positive regulation of caveolin-1, upregulation of E-cadherin and decreased activity of beta-catenin, NF-kappaB and NF-kappaB-regulated gene MMP-2. In animal experiments, lung weights in PBS group (0.31+/-0.07 g) were significantly elevated compared with those in As(2)O(3)-treated groups (0.21+/-0.03 g and 0.17+/-0.03 g) also As(2)O(3) reduced number of metastatic lesions of lungs (15.4+/-3.5 vs. 8.3+/-2.0 and 6.3+/-2.3) in a dose-dependent manner.

CONCLUSIONS

This study is the first to report the effectiveness of As(2)O(3) as an inhibitor of cervical cancer invasion both in vitro and in vivo, suggesting a potential clinical application of As(2)O(3) in cervical cancer therapies combining apoptosis induction and metastasis inhibition.

Identification of differentially expressed genes using annealing control primer-based GeneFishing in human squamous cell cervical carcinoma

AIMS

To compare different gene expression patterns between squamous cell cervical carcinoma (SCC) and normal cervical tissue in Korean women and to identify those genes that are specifically or predominantly expressed in SCC by employing annealing control primer (ACP)-based GeneFishing polymerase chain reaction (PCR).

MATERIALS AND METHODS

Cervical cancer specimens were obtained from patients enrolled at the Department of Obstetrics and Gynecology, Kang Nam St. Mary's Hospital, Catholic University of Korea. We used a common reference that was mixed with an equal amount of RNA extracted from patients without cervical cancer. The profiles of expressed genes were compared between the SCC and normal cervix identified using GeneFishing differentially expressed gene kits, screened by a BLAST search, and confirmed by semi-quantitative reverse transcription-PCR (RT-PCR).

RESULTS

Almost 100 differentially expressed genes were identified in the control and SCC samples. Using 60 arbitrary ACPs, 50 differentially expressed genes were identified, and 30 up-regulated and 20 down-regulated expressed genes were sequenced. Among 50 clones selected by ACP-based GeneFishing PCR, six genes with different expression patterns were determined and confirmed by semi-quantitative RT-PCR. The functional roles of two up-regulated genes, fibrillarin and calgranulin A, and one down-regulated gene, clusterin, were previously identified. However, the functional roles of two up-regulated genes and one down-regulated gene were not identified.

CONCLUSION

We identified distinctive gene expression profiles in Korean women with SCC using ACP-based GeneFishing PCR.

X chromosomal and autosomal loss of heterozygosity and microsatellite instability in human cervical carcinoma

The study analyzes tumor material and normal tissue from 27 patients with pure squamous cell carcinoma of the uterine cervix for loss of heterozygosity (LOH) and microsatellite instability (MSI) on 14 autosomal and 11 X chromosomal loci. Overall, 4-40% of the informative cases showed LOH at autosomal regions with the highest frequency at 3p (21-40%) and a marked frequency at 2q35-q37.1 (12.5%) and 17p13.3 (10%), representing regions with putative tumor suppressor gene (TSG) function. The frequency of X chromosomal LOH ranged from 4% to 20%, with a maximum at Xq28 (20%) and Xq11.2-q12 (17%), again indicating alterations in TSG. A 12% LOH was seen at Xq21.33-q22.3, a region encoding a protein with a regulatory function in the cell cycle via cyclin-dependent kinases. MSI was detected in autosomal regions in up to 7% in regions linked to the X chromosome in up to 11%, probably indicating alterations of mismatch repair mechanisms. Our results and those obtained from the literature suggest that autosomal LOH and MSI in carcinomas of the cervix uteri are predominantly found at regions with putative TSG function. Beside TSG alterations, X chromosomal LOH is probably more strongly connected to disturbances in cell cycle regulation.

Whole genome tiling path array CGH analysis of segmental copy number alterations in cervical cancer cell lines

Cervical cancer is the second most common malignancy in women worldwide, with high risk subtypes of human papillomavirus (HPV) constituting the major etiological agent. However, only a small percentage of women infected by the virus develop disease, suggesting that additional host genetic alterations are necessary for disease progression. In this study we examined the genomes of a panel of commonly used model cervical cancer cell lines using a recently developed whole genome tiling path array for CGH analysis. Detailed analysis of genomic profiles enabled the detection of many novel aberrations, which may have been missed by conventional cytogenetic methods. In total, 27 minimal regions of recurrent copy number alteration were identified that are potentially involved in tumorigenesis. Interestingly, fine mapping of the 3q gain, which is associated with the progression of precursor lesions to invasive cervical cancer, identified a minimal region of alteration harboring genes distinct from previous candidates. Novel regions of gene amplification, including the coamplification of both the Birc and MMP gene clusters on 11q22, were also evident. Lastly, characterization of genomic structure at sites of HPV integration identified the copy number gain of host cellular sequences between the viral-host genomic boundaries in both SiHa and SW756, suggesting a direct role for HPV integration in the development of genetic abnormalities that initiate cervical cancer. This work represents the highest resolution look at a cervical cancer genome to date and offers definitive characterization of the alteration status of these cancer cell lines.

Cidofovir administered with radiation displays an antiangiogenic effect mediated by E6 inhibition and subsequent TP53-dependent VEGF repression in HPV18+ cell lines

Therapeutic administration of the antiviral agent cidofovir with radiation markedly enhanced the antitumor effect of ionizing radiation in cells of two HPV18+ human cervical carcinoma cell lines. Although this potent radiosensitizing effect was associated with repression of the viral oncoproteins E6/ E7 and restoration of TP53 as shown previously, additional mechanisms may be involved. In the present study, we investigated the antiangiogenic effect of the combination of cidofovir and radiation in cells of two HPV18+ cervical cancer cell lines, HeLa and ME180, and assessed the molecular mechanisms associated with the antiangiogenic effect observed. Cells were exposed to cidofovir (10 microg/ml) and irradiated (1-9 Gy). The angiogenic response was studied in vitro by a matrigel invasion assay. Modulations of E6, TP53 and VEGF mRNA and protein levels were studied by real-time RT-PCR, Western blot analysis and ELISA, respectively. Then a double RNA interference approach was used to analyze the connection between E6/TP53 and VEGF. The combination of cidofovir and radiation had a potent antiangiogenic effect. It induced E6 inhibition, restoration of TP53, and reduction of the proangiogenic phenotype of HPV18+ cells associated with VEGF inhibition. A siRNA strategy showed an anti-VEGF action of the combination mediated directly by E6 inhibition and TP53 restoration, since E6 siRNA inhibited VEGF whereas co-transfection with E6 and TP53 siRNA abrogated the anti-VEGF effect. This study showed that the combination of cidofovir with ionizing radiation has an antiangiogenic effect associated with VEGF inhibition subsequent to E6 inhibition and TP53 restoration.

Differential viral loads of human papillomavirus 16 and 58 infections in the spectrum of cervical carcinogenesis

Human papillomavirus (HPV) load was reported to be related to the severity of cervical neoplasia but with controversy. The viral load-disease severity relationship was showed in HPV 16, but no study was made in HPV 58, the second most prevalent HPV in cervical cancer in East Asia. We studied cervical HPV loads in HPV 16- and HPV 58-infected cases of normal, low-grade squamous intraepithelial lesions (LSIL), high-grade squamous intraepithelial lesions (HSIL), and invasive cervical cancer (CC) by using quantitative polymerase chain reaction (Q-PCR) with type-specific primers in defined cell number. With the exception of HPV 16 infection in normal, viral loads varied greatly in each disease regardless of genotypes. The load of HPV 16 differed significantly among disease severities, with a dramatic increase from normal (1.14 +/- 2.25 copies/cell) to LSIL, HSIL, and CC (1599 +/- 2301, 7489 +/- 24,087 and 1878 +/- 2979 copies/cell, respectively) (P < 0.01). No significant difference was noted among different HPV 58 infections, with loads in normal, LSIL, HSIL, and CC of 503 +/- 641, 7951 +/- 27,557, 353 +/- 744, and 1139 +/- 2895 copies/cell, respectively. In comparison with HPV 16, HPV 58 subclinical infection confers a significant higher load (P < 0.01). Different HPV types behave differentially in the spectrum of cervical carcinogenesis. Unlike HPV 16, the infection load of HPV 58 does not correlate to the clinical severity. The wide variation of HPV loads among different HPV types and among squamous intraepithelial lesions and CC makes the viral load test unrealistic in differentiating different severities of cervical neoplasia.

Phenotypic features with p53 alterations related to human papillomavirus and prognostic evaluation in cervical cancer

Cervical cancer is one of the most common tumor affecting women worldwide. Human papillomavirus (HPV) was found to have a causal relationship with cervical cancer and its precursors. The interaction between HPV E6 protein and p53 was identified in in vitro studies. The aim of the study was to evaluate the prevalence of p53 alterations related to HPV infection and the prognostic significance of p53 alterations in cervical cancer. Studies were identified by a MEDLINE search, and all relevant articles were retrieved from 1991 to March 2004. The prevalence of p53 mutations is a rare event in cervical cancer. The correlation between p53 mutations and HPV or prognosis is controversial. Loss of heterozygosity (LOH) of p53 is more commonly found in cervical cancer and is related with the prognosis of this disease. There is no significant correlation between p53 polymorphism and development of cervical cancer. The p53 mutations were not commonly found in cervical cancer. LOH of p53 may contribute to the progression of this malignancy. p53 polymorphism failed to be an independent prognostic factor in predicting the outcome of patients with cervical cancer. Further, epidemiologic surveys should be undertaken in larger populations and in different geographical regions.

Distinct telomere length regulation in premalignant cervical and endometrial lesions: implications for the roles of telomeres in uterine carcinogenesis

Mouse models show that progressive shortening of telomeres with ageing causes chromosomal instability, which can lead to the initiation of cancer. However, it is unclear what roles telomere shortening plays in human carcinogenesis. The present study has investigated the involvement of telomere dynamics in uterine carcinogenesis. Using telomere-FISH (telo-FISH) assays, telomere lengths in premalignant and malignant cervical and endometrial lesions were measured and compared with chromosomal arm loss or gain. Telo-FISH signals were visualized with Cy3-labelled telomere-specific probes and presented as telomere intensity (TI). Early-stage cervical intraepithelial neoplasias (CINs), especially CIN2, had significantly shorter telomeres than corresponding normal squamous epithelia (p = 0.019), together with increased rates of chromosomal arm loss/gain (p < 0.001). Cervical cancers had relatively short telomeres, but they also showed greater heterogeneity than other sampled tissues, including those with long telomeres. In contrast, there was no significant difference between the telomere length of normal endometrium and of endometrial hyperplasia and endometrial cancer. There was no significant difference in the rate of chromosomal arm loss/gain between normal endometrium and endometrial hyperplasia. These findings suggest that progressive shortening of telomeres occurs in CIN, in association with chromosomal instability, which may play critical roles in cervical carcinogenesis. In contrast, endometrial hyperplasias have relatively stable telomeres without widespread chromosome alteration, implying that endometrial carcinogenesis involves mechanisms distinct from those of cervical carcinogenesis, possibly including microsatellite instability.

Aberrant expression of alpha-dystroglycan in cervical and vulvar cancer

OBJECTIVES

Cervical and vulvar cancers develop through well-defined precursor lesions but their exact pathogenesis is still unknown. The dystroglycan complex is a transmembrane glycoprotein that forms a continuous link from the extracellular matrix to the actin cytoskeleton. Deregulated expression of dystroglycan has been reported in human malignancies and related to tumor differentiation and aggressiveness. In this study, expression of dystroglycan was evaluated in the multistep cervical and vulvar tumorigenesis.

METHODS

Expression of the dystroglycan complex was evaluated by immunostaining in lesions representing different stages of vulvar and cervical tumorigenesis using a monoclonal antibody which recognizes carbohydratic epitopes on the alpha-dystroglycan subunit.

RESULTS

alpha-dystroglycan was constantly detected in normal cervical epithelium with a mean percentage of positive cells higher than 80%. A progressive significant reduction in the mean percentage of positive cells was observed in low (67%) and high grade SIL (14%) and in invasive carcinomas (2.6%) of the cervix. In cancers, no differences were observed in terms of percentage of positive cells when cases were stratified according with either tumor grade or stage. A progressive significant reduction in the mean percentage of positive cells was also observed from normal vulvar epithelium (90%) to VIN1 (66%), VIN2 (28%) and invasive vulvar carcinomas (22%). No significant decrease in the alpha-dystroglycan staining was observed in squamous cell hyperplasia lesions (85%) while lichen sclerosus displayed a percentage of positive cells (47%) significantly lower than normal epithelium.

CONCLUSIONS

Detection of alpha-dystroglycan is frequently lost in human cervical and vulvar tumorigenesis and further studies are warranted to verify whether evaluation of this molecule might serve as marker of risk progression of preneoplastic lesions and to better understand its significance in terms of cancer development.

NOL7 is a nucleolar candidate tumor suppressor gene in cervical cancer that modulates the angiogenic phenotype

Cervical cancer is associated with human papilloma virus infection. However, this infection is insufficient to induce transformation and progression. Loss of heterozygosity analyses suggest the presence of a tumor suppressor gene (TSG) on chromosome 6p21.3-p25. Here we report the cloning NOL7, its mapping to chromosome band 6p23, and localization of the protein to the nucleolus. Fluorescence in situ hybridization analysis demonstrated an allelic loss of an NOL7 in cultured tumor cells and human tumor samples. Transfection of NOL7 into cervical carcinoma cells inhibited their growth in mouse xenografts, confirming its in vivo tumor suppressor activity. The induction of tumor dormancy correlated with an angiogenic switch caused by a decreased production of vascular endothelial growth factor and an increase in the production of the angiogenesis inhibitor thrombospondin-1. These data suggest that NOL7 may function as a TSG in part by modulating the expression of the angiogenic phenotype.

P16INK4a expression as a potential prognostic marker in cervical pre-neoplastic and neoplastic lesions

An immunohistochemical analysis with monoclonal antibody p16(INK4a) was performed in formalin-fixed, paraffin-embedded samples of 60 cases. The aim was to investigate in biopsies the expression of p16(INK4a) of normal uterine cervical tissue, pre-cancerous and cancerous lesions, and their relation with human papilloma virus (HPV) and HIV status. Three parameters were evaluated: percentage of p16(INK4a) positive cells, reaction intensity, and cell staining pattern. All of these parameters were statistically different when compared among different histological groups. However, logistic regression model showed that the reaction intensity was the best indicator of the expression of p16(INK4a). This expression increases from normal to invasive squamous carcinoma. Sixty-six percent of the patients with CIN grade 1 (CIN1) expressed p16(INK4a) (all these cases were infected with high risk HPV). Our study supports the hypothesis that p16(INK4a) expression in pre-cancerous lesions and cancers can be used to identify HPV-transformed cells. Of great interest for routine diagnostic use is the fact that immunohistochemical testing for p16(INK4a) seems to be capable of identifying HPV-positive cells and potentially recognizing those lesions with an increased risk of progression to high-grade lesions.

Warthin Tumors Do Not Have Microsatellite Instability and Express Normal DNA Mismatch Repair Proteins

Context.—Warthin tumors are controversial entities with a poorly understood etiology. Although some investigators have suggested a neoplastic origin, others have supported a developmental anomaly. A recent study described the absence of staining for hMLH1 and hMSH2 proteins in the epithelial component of Warthin tumors, suggesting that they arise secondary to defects in the DNA mismatch repair system.

Objective.—To determine if Warthin tumors exhibit evidence of DNA mismatch repair defects.

Design.—Immunostains for hMLH1 and hMSH2 were performed using a standard approach. Microdissection of the epithelial component was followed by DNA extraction from the tissue fragments. Polymerase chain reaction and capillary electrophoresis analyses were performed for the following 5 National Cancer Institute–recommended microsatellites: D2s123, D5s346, D17s250, BAT25, and BAT26.

Patients.—Twelve patients with Warthin tumors were included.

Results.—The immunostains for hMLH1 and hMSH2 showed preserved expression in the nuclei of the epithelial component of all Warthin tumors. No microsatellite instability was detected, and no loss of heterozygosity was seen.

Conclusions.—These results are not concordant with previously reported results showing loss of expression of the hMLH1 and hMSH2 DNA mismatch repair enzymes in the epithelial component of Warthin tumors. Furthermore, no microsatellite instability was detected in the 5 loci tested for each tumor in this series. These data demonstrate that Warthin tumors do not have evidence of DNA mismatch repair defects at the genomic or protein expression level.

Cancer susceptibility in nasopharyngeal carcinoma families--a population-based cohort study

Undifferentiated nasopharyngeal carcinoma is a result of environmental factors, in particular EBV infection, affecting genetically susceptible individuals. The familial risk of nasopharyngeal carcinoma is among the highest of any malignancy. Whether this susceptibility is restricted to nasopharyngeal carcinoma is unknown as information on the risk of other cancers in relatives is limited. We did a population-based study of the cancer incidence in nasopharyngeal carcinoma families in Greenland, a nasopharyngeal carcinoma-endemic area. Using population-based registers, a cohort of all persons born in Greenland was followed from 1973 to 2002. In this cohort, 134 individuals developed nasopharyngeal carcinoma and their relatives were identified through registers and interviews. Subsequently, the occurrence of cancer was determined by linkage to the population-based cancer register and the risk of cancer in nasopharyngeal carcinoma relatives and nonrelatives compared by relative risks. Among 766 first-degree relatives, the relative risk of nasopharyngeal carcinoma following the family index case was 8.0 [95% confidence interval (95% CI), 4.1-14.0]. Sex and age of the relative or the index case had no modifying effect on the familial risk of nasopharyngeal carcinoma. The relative risks of carcinoma of the salivary glands, 8.4 (95% CI, 2.7-19.5), and uterine cervix, 2.2 (95% CI, 1.1-3.9), were also significantly increased. In families with multiple cases of nasopharyngeal carcinoma, the risk of other cancers than nasopharyngeal carcinoma was further increased. These results indicate that the increased risk of cancer in nasopharyngeal carcinoma families is not restricted to nasopharyngeal carcinoma, but extends to the virally associated cancers of the salivary glands and cervical uteri.

Chlamydia trachomatis modulates expression of tumor suppressor gene caveolin-1 and oncogene C-myc in the transformation zone of non-neoplastic cervical tissue

OBJECTIVES

The obligate intracellular bacterium Chlamydia trachomatis is frequently found in association with benign proliferative, pre-neoplastic and malignant changes in cervical epithelium. The present study addresses the possible role of C. trachomatis infection of the uterine cervix in modulating human cancer gene expression.

METHODS

RNA was extracted from both C. trachomatis infected and non-infected human fibroblast cultures treated with ITFgamma. The extracted RNA was used for cDNA microarrays carrying 33,000 human genes to detect abnormal gene expression induced by Chlamydia. Forty specimens of cervix dissected from the transformation zone had previously tested negative for HPV and positive for C. trachomatis by standard DNA PCR (20). These samples were subjected to RT-PCR to detect the expression of the abnormal genes induced by Chlamydia infection.

RESULTS

The ITFgamma-induced, non-replicative Chlamydia-infected fibroblast cultures showed significant modulation of gene expression. The cultures showed a 2-fold decrease in the expression of the gene coding for the tumor suppressor caveolin-1, and increased expression of the oncogene C-myc, a promoter of cervical carcinogenesis. In tissues from the Chlamydia-infected cervical transformation zone, real-time RT-PCR demonstrated a highly significant average 4.7-fold reduction of caveolin-1 mRNA (P < or = 0.0001) and an average 2.1-fold increase in C-myc (P < 0.05).

CONCLUSIONS

Human ITFgamma-treated fibroblasts as well as non-neoplastic cervical tissues responded to C. trachomatis with a strong down-regulation of caveolin-1 mRNA and a light up-regulation of C-myc mRNA. These changes were independent of the HPV high-risk types. This study reveals possible mechanisms by which C. trachomatis infection may contribute to neoplastic changes in the transformation of uterine cervix. These possible mechanisms require further evaluation.

Emerging issues of the expression profiling technologies for the study of gynecologic cancer

Evaluation of the prognostic parameters of gynecologic cancer has shown their failure for classification according to the clinical behavior or the prediction of its outcome. This weakness has important implications on prognosis and treatment. The increasing understanding of the complexity of the human genome, coupled with the development of high throughput analysis techniques and bioinformatics tools, has changed our concepts on cancer biology, by shifting our targets to a global analysis of the transcriptome and the proteome, linking genes and their products into functional pathways. These approaches permit the documentation of expression patterns of thousands of genes within a cell. With the use of DNA microarray technology, it is feasible to identify signature patterns of expression in tumor samples that faithfully correlate with its biology, providing accurate prognosis for each cancer patient and thus a rational customized treatment. At this stage, there is a need for systematic studies for the validation of these novel approaches. In this review, we provide a basic background of the concept of the technology, highlight several emerging issues from their applications on gynecologic cancer, discuss a series of important themes and problems regarding their interpretation and relevance for the clinicians, and comment on future areas of research.

Down-regulation of peroxisome proliferator-activated receptor gamma in human cervical carcinoma

OBJECTIVE

Peroxisome proliferator-activated receptor gamma (PPARgamma) is a member of the nuclear hormone receptor superfamily. Treatment of PPARgamma ligands has been shown to inhibit the growth of various human cancer cells. However, it has not been reported whether human cervical carcinoma cells express PPARgamma. In this study, we investigated the expression of PPARgamma in human normal cervix and cervical carcinoma tissues, and as well as the effect of PPARgamma ligands on cervical cancer cells survival.

METHODS

Fresh cervical tissues from a study group of 10 study patients diagnosed with cervical carcinoma were analyzed for the expression of PPARgamma using real-time RT-PCR and Western blot analysis. Immunohistochemical staining for PPARgamma was also performed on the serial sections of 40 cervical carcinomas. In addition, we evaluated the feasibility of PPARgamma ligands, as a potential therapeutic drug against cervical cancer cells using MTT assay and FACS analysis.

RESULTS

We found that there were lower expression levels of PPARgamma mRNA and protein in cervical carcinoma tissues than in normal cervical tissues. The extent and intensity of immunoreactive PPARgamma in normal cervix tissues were statistically much greater than those of carcinoma tissues. In order to study effects of PPAR ligand on cell proliferation, we chose ciglitizone that showed very potent growth inhibitory effects on the proliferation of two human cervical cancer cell lines (C-33-A and C-4II). C-4II cells express high expression of PPARgamma, while C-33A cells express low level of PPARgamma. Treatment with ciglitizone inhibited the growth of C-4II cells in a dose-dependent manner, while the growth inhibitory effect of ciglitizone was much less in C-33A cells. In order to test whether ciglitizone-induced growth suppressive effects on cervical cancer cell lines is PPAR-dependent, we treated cervical cancer cells with ciglitizone and/or GW9662 (a PPARgamma antagonist). No significant difference in cell survival was found in cells treated with ciglitizone alone vs. co-treated with ciglitizone and GW9662. GW9662 alone did not induce any cell growth arrest in the cells that we used (data not shown). Thus, we concluded that growth suppressive effects by ciglitizone may not be dependent upon status of PPAR expression. To clarify the mechanism by which ciglitizone inhibits the growth of cervical carcinoma cells, flow cytometry and Western blotting assay were performed. As results, we demonstrated that a large portion of C-4II cells (but not in C-33A) after ciglitizone treatment were arrest at G1 phase with the induction of p21(Cip1/Waf1) and p27(kip1) protein.

CONCLUSIONS

These results suggest that PPARgamma is down-regulated in multiple human cervical cancer tissues and cell lines. Ciglitizone may suppress human cervical cancer cells in PPAR-independent manner.

TP53 codon 72 polymorphism and risk for cervical cancer in Portugal

High-risk human papillomavirus are essential for the development of cervical cancer; however, TP53 is the most frequently altered tumor suppressor gene among tumors and is described as a cofactor for cervical carcinogenesis. TP53 has two common polymorphic forms encoding either proline or arginine, at position 72, and the presence of homozygous arginine has been reported as a risk factor for cervical cancer in many populations. We evaluated the effect of this TP53 polymorphism in a northern Portuguese population. We analyzed blood samples of 385 women; 20 with low-grade squamous intraepithelial lesion (SIL), 56 with high-grade SIL, 164 with invasive cervical cancer, and 145 healthy controls, using allele specific-polymerase chain reaction methodology. We observed an increased frequency of the Arg/Arg genotype in the cancer group, but no statistical significance was found between cases and controls (P>0.05). Our results indicate that there is no association between the presence of the Arg allele in codon 72 of TP53 polymorphism and risk of cervical cancer in our population.

Deletion in chromosome 11 and Bcl-1/Cyclin D1 alterations are independently associated with the development of uterine cervical carcinoma

PURPOSE

The aim of this study was to understand whether there is any association between specific deleted regions in chromosome 11 (chr.11) and alteration (amplification/rearrangement) of Bcl-1/Cyclin D1 locus, located at 11q13, in uterine cervical carcinoma (CA-CX).

METHODS

The deletion mapping of chr.11 was studied using 17 highly polymorphic microsatellite markers in 65 primary uterine cervical lesions. The Bcl-1/Cyclin D1 alterations were analyzed by Southern blot and/or polymerase chain reaction (PCR) method in respective cervical lesions.

RESULTS

Chr.11 deletion was found to be significantly associated with progression of CA-CX. High frequency (48-65%) of deletion was found in 11p15.5 (D1), 11q22.3-23.1(D2), and 11q23.3-24.1(D3) regions and significant association was seen among deletions in D2 and D3 regions. Bcl-1/Cyclin D1 locus alteration was observed in overall 27% cervical lesions. Co-amplification of Bcl-1/Cyclin D1 locus was seen in 10% samples. However, no association was found between the deleted regions and Bcl-1/Cyclin D1 locus alterations.

CONCLUSIONS

Our study suggests that there is no co-operativity between the deleted regions (D1- D3) in chr.11 and Bcl-1/Cyclin D1 alterations, but these alterations may provide cumulative effect in progression of the tumor. The D1-D3 regions may harbor candidate tumor suppressor gene(s) (TSGs) associated with the development of CA-CX.

Genomic imbalances in 70 snap-frozen cervical squamous intraepithelial lesions: associations with lesion grade, state of the HPV16 E2 gene and clinical outcome

Host genomic abnormalities may determine the natural history of cervical squamous intraepithelial lesions (SILs). We undertook comparative genomic hybridisation analysis of epithelium carefully microdissected from 70 cervical SILs, the largest series to date. In contrast to previous studies, we used frozen sections for optimal DNA quality and examined whether patterns of DNA copy number imbalance (CNI) are characteristic of SIL grade, human papillomavirus (HPV) status and postoperative recurrence. We identified more CNIs in cervical SIL than previously described, with more CNIs per case in high-grade squamous intraepithelial lesion (HG-SIL) than in low-grade squamous intraepithelial lesion (LG-SIL) (P=0.04). While some CNIs were seen at similar frequencies in HG-SIL and LG-SIL, others, including gain on 1q, 3q and 16q, were found frequently in HG-SIL but not in LG-SIL. There were significantly more CNIs per case in HG-SILs showing loss of the HPV16 E2 gene (a repressor of viral oncogene transcription) (P=0.026) and in HG-SILs that subsequently recurred (P=0.04). Our data are consistent with sequential acquisition of CNIs in cervical SIL progression. Higher frequency of CNI in association with E2 gene loss supports in vitro evidence that high-risk HPV integration is associated with genomic instability. Further investigation of the clinical value of specific host genomic abnormalities in cervical SIL is warranted.

Clinicopathologic significance of loss of heterozygosity on chromosome 1 in cervical cancer

OBJECTIVES

We studied the loss of heterozygosity (LOH) in chromosome 1 in squamous cell carcinoma (SCC) of the uterine cervix and evaluated its clinical and pathological significance.

METHODS

Sixty-three highly polymorphic markers were used to study the LOH in 84 SCC. Microdissection was performed to enrich the tumor cells population before the alleotyping study. The findings were correlated with clinicopathologic findings.

RESULTS

LOH was detected in all but one SCC. The number of loci showing LOH in each case ranged from 0 to 41. Five loci showed LOH in > or =30% SCC and 28 other loci had an LOH frequency between 20% and 30%. Six of the eight markers located at 1p36.21 to 1p36.33 had a frequency of LOH >20%. Shortened total survival was associated with LOH at 14 loci and shortened disease-free survival was associated with LOH at 11 loci while LOH at nine loci were associated with both. A high frequency of LOH was associated with stage as well as shortened total and disease-free survival.

CONCLUSIONS

LOH is a common and early event in the development of cervical SCC. Tumor suppressor genes may be present at 1p36. The incidence of LOH increases as the tumor progresses but a high frequency of LOH is not an independent prognostic factor.

Identification of novel prognostic markers in cervical intraepithelial neoplasia using LDMAS (LOH Data Management and Analysis Software)

Background

Detection of Loss of Heterozygosity (LOH) is one of the most common molecular applications in the study of human diseases, in particular cancer. The technique is commonly used to examine whether a known tumour suppressor gene is inactivated or to map unknown tumour suppressor gene(s). However, with the increasing number of samples analysed using different software, no tool is currently available to integrate and facilitate the extensive and efficient data retrieval and analyses, such as correlation of LOH data with various clinical data sets.

Results

An algorithm to identify prognostic disease markers is devised and implemented as novel software called LDMAS. LDMAS is a software suite designed for data retrieval, management and integrated analysis of the clinico-pathological data and molecular results from independent databases. LDMAS is used in stratification of disease stages according to clinical stage or histological features and correlation of various clinico-pathological features with molecular findings to obtain relevant prognostic markers such as those used in predicting the outcome of cervical intraepithelial neoplasia (CIN). This approach lead to the identification of novel prognostic cervical cancer markers and extraction of useful clinical information such as correlation of Human Papilloma Virus (HPV) status with CIN lesions.

Conclusions

A novel software called LDMAS is implemented and used to extract and identify prognostic disease markers. The software is used to successfully identify 4 novel prognostic markers that can be used to predict the outcome of CIN. LDMAS provides an essential platform for the extraction of useful information from large amount of data generated by LOH studies. LDMAS provides three unique and novel features for LOH analysis : (1) automatic extraction of relevant data from patient records and reports (2) correlation of LOH data with clinico-pathological data and (3) storage of complex data in flexible format. The first feature automates the creation of database of clinically relevant information from huge amount of data, the second feature extracts useful biomedical information such as prognostic markers in CIN and the third feature simplifies the statistical analyses of the data and allows non-statisticians to carry out the analysis. Additionally, LDMAS can be used to extract clinically useful markers from other diseases and interface to high throughput genotyping analysis software such as GDAS used to generate LOH data from Affymetrix^® GeneChip Mapping arrays.

Predictive significance of the alterations of p16INK4A, p14ARF, p53, and proliferating cell nuclear antigen expression in the progression of cervical cancer

PURPOSE

The purpose of this research was to evaluate the clinical significance of p16INK4A, p14ARF, p53, and proliferating cell nuclear antigen (PCNA) expression in tumor progression of cervical cancer.

DESIGN

Seventeen patients (40 samples) with consecutive cervical lesions from normal squamous epithelium, inflammation of the cervix to cervical intraepithelial neoplasm (CIN) and invasive cervical squamous cell cancer (SCC), or from CIN to SCC were collected for this study. Expression of p16INK4A, p14ARF, p53, and PCNA were detected by immunohistochemistry on paraffin-embedded sections. Human papillomavirus DNA was detected simultaneously with PCR and typed according to its DNA sequence.

RESULTS

p16INK4A overexpression was significantly higher in CIN (75%) and in SCC (75%) than in normal or inflammation of the cervix (12.5%; P < 0.01, P < 0.05, respectively). The positive rate of p14ARF expression was higher in SCC (83%) than in normal/inflammation of the cervix (25%; P < 0.05). PCNA expression was negative in normal or inflammation of the cervix, but an increased in expression was seen in 63.2% in CIN and 100% in SCC (P < 0.01, P < 0.05). When the time interval for disease progression from initial biopsy to CIN 3 or invasive cancer was compared with states of p16INK4A expression, cases stained positive for p16INK4A progressed within 64.2 months as compared with 122.3 months among those stained negatively (P < 0.01). Cases with increased p14ARF expression also had a short time interval for disease progression of 78.8 months as compared with 108.3 months in cases that were p14ARF negative. Cases with stable or decreased p53 expression had the shortest time interval for progression of 32.3 months in contrast to cases with no p53 expression (113.9 months). However, cases with increasing p53 expression progressed within 60.8 months.

CONCLUSIONS

Our results suggested that altered states of p16INK4A, p14ARF, p53, and PCNA may be valuable markers to predict the progression of cervical neoplasia.

Analysis of molecular alterations in chromosome 8 associated with the development of uterine cervical carcinoma of Indian patients

OBJECTIVES

We have been done the detailed deletion mapping of chromosome (chr.) 8p21.3-23 to localize the candidate tumor suppressor gene(s) (TSGs) loci as well as studied the mechanism of activation of c-myc gene, located at chr.8q24.1, by analyzing the amplification/rearrangement/HPV integration within approximately 580 kb of c-myc locus in uterine cervical carcinoma (CaCx) of Indian patients. The association between the deletions in chr.8p21.3-23 and alterations in the c-myc locus has also been analyzed.

METHODS

The deletion mapping of chr.8p21.3-23 was done by 15 microsatellite markers and the alterations in the c-myc locus were analyzed by Southern hybridization using the pal-1/c-myc/mlvi-4/HPV 16/18 probes in seven cervical intraepithelial neoplasia (CIN) and 55 primary uterine cervical carcinoma. The alterations in chr.8p/q have been correlated with the different clinicopathological parameters.

RESULTS

Three discrete minimal deleted regions with high frequencies of loss of heterozygosity (LOH) (37-43%) were identified in the chr.8p23.1-23.2 (D1), 8p23.1 (D2), and 8p 21.3-22 (D3) regions within 0.41-4.62 Mb. The deletion in the D1 region was significantly associated with the deletion in the D2 region (P = 0.03), whereas the deletion in D2 was marginally associated with the deletion in the D3 region (P = 0.07). The alterations in the c-myc locus were seen in 43% of the samples. About 35% of the samples showed coalterations in both arms of chr.8. No significant association was observed with the alterations in chr.8p/q as well as with the different clinicopathological parameters.

CONCLUSIONS

The deletions in chr.8p21.3-23 and the alterations in the c-myc locus are independently associated with the development of CaCx. The D1-D3 regions in chr.8p21.3-23 could harbor candidate TSGs associated with the development of this tumor. The c-myc gene was activated by amplification/rearrangement at the pal-1/c-myc/mlvi-4 loci as well as HPV integration in the pal-1 locus in this tumor.

Cervical intraepithelial neoplasia: prognosis by combined LOH analysis of multiple loci

OBJECTIVE

Cervical intraepithelial neoplasias (CIN) show markedly variable clinical behavior. Clinically, it is important to distinguish CIN lesions with different behaviors and identify those likely to persist and progress. The purpose of this study is to explore whether CIN lesions with different clinical behaviors can be stratified by analysis of loss of heterozygosity (LOH) at multiple loci.

METHODS

One hundred sixty-four cases of CIN (54 CIN1, 59 CIN2 and 51 CIN3) were screened for LOH at 12 microsatellite markers including 10 from 3p14, 3p21-22, 6p21 and 11q23. LOH was correlated with clinical follow-up data and high-risk HPV infection.

RESULTS

In a pilot study of 71 cases of CIN, screening of 12 microsatellite markers identified four (D3S1300, D3S1260, D11S35, and D11S528) at which LOH was significantly associated with disease persistence/progression. These four markers were further investigated in a larger cohort, which brought the total number of cases examined to 164. Combined analysis of LOH at the above four loci permitted the identification of 22-47% of CIN lesions depending on the histological grade, which showed disease persistence/progression. LOH at these loci was significantly associated with HPV16 infection. Bioinformatic analysis identified several candidate genes including the fragile histidine triad gene and progesterone receptor gene that may be the target of deletions.

CONCLUSIONS

LOH at D3S1300, D3S1260, D11S35 and D11S528 was significantly associated with cins that showed persistence/progression, and combined LOH analyses at these loci could be used to identify such cases.

Quantification of human papillomavirus DNA in the plasma of patients with cervical cancer

Plasma human papillomavirus (HPV)-DNA level was measured to evaluate the clinical usefulness of circulating DNA for cervical cancer management. DNA extracted from pretreatment plasma of 50 cervical cancer patients and from serial longitudinal plasma of 21 patients was quantified for HPV16/HPV18 by means of quantitative polymerase chain reaction. Another 15 patients with low-grade lesion (LG), 18 patients with high-grade lesion (HG), and 96 normal individuals were studied as controls. Plasma HPV16-DNA was detectable in 50% of cancer patients. The incidence and median level were statistically higher than those in LG patients and normal, but similar to HG patients. Plasma HPV18-DNA was only detected in 6% of cancer patients and 1% of normal. Same type of HPV present in plasma was also detected in its primary tumor; and the level of plasma HPV16-DNA was dependent on the viral load in primary tumor. Plasma HPV-DNA was not detected in 16 of 21 patients after treatment, and those patients had complete response to therapy. HPV-DNA persisted or reappeared in five patients after treatment (one had persistent disease and another had recurrence). Plasma HPV-DNA might be a valuable marker for monitoring therapeutic response and disease progression in cervical cancer.

Intratumor chromosomal heterogeneity in advanced carcinomas of the uterine cervix

Intratumor heterogeneity in chromosomal aberrations is believed to represent a major challenge in the treatment of cancer. The aim of our work was to assess the chromosomal heterogeneity of advanced cervical carcinomas and to distinguish aberrations that had occurred at a late stage of the disease from early events. A total of 55 biopsies, sampled from 2-4 different sites within 20 tumors, were analyzed by use of comparative genomic hybridization. Heterogeneous aberrations were identified as those present in at least 1 of the biopsies and which were not seen, nor seen as a tendency, in the others of the same tumor. The homogeneous aberrations were those seen in all biopsies of the tumor. The most frequent homogeneous aberrations were gain of 3q (65%), 20q (65%) and 5p (50%), indicating that these are early events in the development of the disease. Chromosomal heterogeneity was observed in 11 tumors. The most frequent heterogeneous aberrations were loss of 4p14-q25 (60% of 10 cases with this aberration), and gain of 2p22-pter (50% of 6 cases), 11qcen-q13 (33% of 9 cases) and 8q (27% of 11 cases), suggesting that these events promote progression at a later stage. Many of the heterogeneous regions contained genes known to influence the prognosis of cervical cancer, such as 7p (EGFR), 8q (c-MYC), 11qcen-q13 (CCND1) and 17q (ERBB2). Three evolution sequences for the subpopulations in the heterogeneous tumors were identified: a serial, a parallel and a mixed sequence. In 2 tumors with a serial sequence, it was indicated that the aberrations +8 and -X had occurred after the other heterogeneous aberrations and hence were the aberrations most recently formed. Our results suggest pronounced chromosomal instability in advanced cervical carcinomas. Moreover, aggressive and treatment-resistant subpopulations may emerge at a late stage and possibly contribute to a poor prognosis of the advanced stages.

Analysis of chromosomes 3, 7, X and the EGFR gene in uterine cervical cancer progression

The aim of this study was to investigate the possible role of genetic alterations in the genesis and progression of cervical carcinomas. We analysed the 3, 7, X aneusomy of chromosomes and the status of the epidermal growth factor receptor (EGFR) gene by fluorescence in situ hybridisation (FISH) analysis. Polysomy of chromosomes 3 and X defined the transition from high-grade squamous intraepithelium lesions (HSIL) to cervical carcinoma. Chromosome 7 monosomy and polysomy did not show any statistical significant differences between the groups examined. When we compared the chromosomal aneusomies in all of the specimens using the Kruskal-Wallis test, significant differences (P = 0.0001, P = 0.0001 for chromosomes 3 and X, respectively) were observed. Using a ratio of the EGFR gene signals and chromosome 7 centromeric signals, no samples showed gene amplification. Our results demonstrate the importance of chromosomal 3 and X aneusomies in the development and progression from HSIL to cervical carcinoma, highlighting their usefulness as genetic markers for identifying SILs at high-risk of progression.

Acquisition of high-level chromosomal instability is associated with integration of human papillomavirus type 16 in cervical keratinocytes

Whereas two key steps in cervical carcinogenesis are integration of high-risk human papillomavirus (HR-HPV) and acquisition of an unstable host genome, the temporal association between these events is poorly understood. Chromosomal instability is induced when HR-HPV E7 oncoprotein is overexpressed from heterologous promoters in vitro. However, it is not known whether such events occur at the "physiologically" elevated levels of E7 produced by deregulation of the homologous HR-HPV promoter after integration. Indeed, an alternative possibility is that integration in vivo is favored in an already unstable host genome. We have addressed these issues using the unique human papillomavirus (HPV) 16-containing cervical keratinocyte cell line W12, which was derived from a low-grade squamous intraepithelial lesion and thus acquired HPV16 by "natural" infection. Whereas W12 at low passage contains HPV16 episomes only, long-term culture results in the emergence of cells containing integrated HPV16 only. We show that integration of HPV16 in W12 is associated with 3' deletion of the E2 transcriptional repressor, resulting in deregulation of the homologous promoter of the integrant and an increase in E7 protein levels. We further demonstrate that high-level chromosomal instability develops in W12 only after integration and that the forms of instability observed correlate with the physical state of HPV16 DNA and the level of E7 protein. Whereas intermediate E7 levels are associated with numerical chromosomal abnormalities, maximal levels are associated with both numerical and structural aberrations. HR-HPV integration is likely to be a critical event in cervical carcinogenesis, preceding the development of chromosomal abnormalities that drive malignant progression.

Microsatellite analysis of early stage (Ia-IIb) uterine cervical squamous carcinoma

Cervical cancer is the most common gynecologic malignancy of the developing world. The oncogenic role of human papilloma virus (HPV) is well known. Attention is now focusing on the complicit genetic changes, which allow progression of these tumors. Regarding these changes, deletion of tumor suppressor genes (loss of heterozygosity [LOH]) is the preferred pathway of progression with only a subset manifesting microsatellite instability (MSI). Implicated loci include 3p14.1-22. Several studies suggest that the mutator phenotype in cervical cancer may correlate with higher grade tumors, more advanced disease stage, and poor outcome. Unlike colorectal cancer, in which an inverse relationship has been demonstrated between microsatellite instability and loss of heterozygosity, cervical cancers expressing MSI have been found to coexpress LOH at other loci. In this study we analyzed 8-microsatellite loci including p53, DCC, APC, the MMR gene hMLH1 and 2 regions of interest on chromosome 3 in a high-risk population group in which HPV infection is endemic.

Decreased expression of the CDK inhibitor p27Kip1 and increased oxidative DNA damage in the multistep process of cervical carcinogenesis

OBJECTIVE

The expression of the CDK inhibitor p27Kip1 and the extent of endogenous oxidative DNA damage were evaluated in the multistep cervical carcinogenesis.

METHODS

Archival specimens of low-grade (L) squamous intraepithelial lesions (SILs) (n=32), high-grade (H) SILs (n=24) and invasive carcinomas (n=48) of the cervix were included in the analysis compared with normal cervical squamous epithelium (n=15). Expression level of p27Kip1 was evaluated by immunostaining. Immunohistochemical detection of 8-hydroxydeoxyguanosine (8-OHdG) was considered as marker of oxidative DNA damage in the same tissues.

RESULTS

p27Kip1 was constantly expressed in normal epithelium with a mean percentage of positive cells higher than 50%. A progressive significant reduction in the mean percentage of positive cells was observed in L-SIL (18.1%), H-SIL (7.3%) and in invasive carcinomas (2.5%). A progressive significant increase in the levels of 8-OHdG and in the percentage of mean positive cells was observed from L-SIL (2.2%) to H-SIL (12.5%) to invasive carcinomas (25.2%). p27Kip1 and 8-OHdG expression displayed a significant inverse relationship.

CONCLUSIONS

Expression of p27Kip1 is down-regulated while oxidative DNA damage increases during cervical carcinogenesis. Both parameters are altered at early stages of the process and might help to predict patients at high risk of progression.

Differential deletions of chromosome 3p are associated with the development of uterine cervical carcinoma in Indian patients

BACKGROUND

Deletions in chromosome 3 occur frequently in uterine cervical carcinoma (CA-CX). The common consensus regions deleted during CA-CX development are not well defined, and have not been correlated with tumour progression.

AIMS

To define specific regions of chromosome 3 deleted during development of CA-CX and to correlate these with clinicopathological data.

METHODS

Deletion mapping of chromosome 3 was done in seven cervical intraepithelial neoplasia (CIN) and 43 primary CA-CX samples using 20 highly polymorphic microsatellite markers.

RESULTS

Deletions of chromosome 3 were significantly associated with tumour progression. High frequencies (33-53%) of loss of heterozygosity (LOH) were found in 3p26.1, 3p22.3, 3p21.2, and 3p13, suggesting the location of putative tumour suppressor genes (TSGs) in these regions. Among these four regions, deletions in 3p21.2 were suggested to occur early during CA-CX development. A significant correlation was found between LOH at 3p26.1 and 3p22.3 with tumour progression from stage I/IIB to stage III/IV. No association was found with the highly deleted regions and human papillomavirus positivity, parity, or menopausal status. Microsatellite size alteration was seen in only seven of the samples. However, rare biallelic alterations were seen in and around the highly deleted regions. Loss of normal copy of chromosome 3 and interstitial alterations in chromosome 3p were seen in some samples.

CONCLUSION

These four regions on chromosome 3p may be differentially deleted during specific stages of CA-CX development. The putative TSGs located in these regions may have a cumulative effect on tumour progression.

Chapter 5: Viral and host factors in human papillomavirus persistence and progression

Understanding the interdependent roles that host and viral factors play in cervical cancer pathogenesis is important for distinguishing women at the highest risk of human papillomavirus (HPV) persistence and progression to cervical cancer. Ongoing research on viral factors such as viral variants is providing important clues regarding HPV oncogenesis; the comprehensive characterization of the HPV genome and the function of viral genes by HPV type and variant will further this understanding. Although the biologic importance of viral integration and viral load measurements in cervical neoplasia is still being debated, available data are difficult to interpret because of methodologic limitations; to sufficiently address the importance of these events will require further methods validation and subsequent application in epidemiologic studies. Continued and expanded investigation of host immune responses-humoral, cellular, and innate immunity-should specifically address the outcomes of HPV persistence and progression to cervical cancer. Molecularly based assays paired with functional assays will be integral toward the identification and validation of key immune pathways and genes specifically relevant to cervical cancer pathogenesis. Novel technologies such as gene expression microarrays will further allow comprehensive identification of relevant genes that are important at various stages of cervical pathogenesis. The study of viral and host factors will undoubtedly lead to markers that may hold diagnostic and/or prognostic value; the clinical validity and utility of these molecular events will, therefore, need to be carefully assessed before implementation in a population setting.

HPV e carcinogênese oral: revisão bibliográfica

O Papilomavírus humano (HPV) é um vírus ubíquo de DNA, epiteliotrópico, que tem a pele e as mucosas como principais sítios de infecção. Ultimamente, a sua associação com neoplasias benignas e malignas da cavidade oral, principalmente o carcinoma epidermóide, tem sido mais evidente. O seu achado comum em epitélio de mucosa oral normal, amplamente divulgado na literatura, não permite inferências mais precisas quanto ao seu papel na carcinogênese (se agente etiológico principal, coadjuvante ou simples habitante do epitélio de revestimento da mucosa oral). São mais de 100 tipos já identificados, dos quais 24 já foram localizados na cavidade oral. Desses, 4 são particularmente importantes, os tipos 6 e 11 (que estão envolvidos nas lesões benignas do epitélio oral) e 16 e 18 (comprovadamente carcinogênicos e possivelmente envolvidos na etiologia de determinados carcinomas epidermóides orais). A ação desses dois últimos tipos está principalmente associada às oncoproteínas E6 e E7 produzidas pelos mesmos. A E6 liga-se, seqüestra e degrada a p53, importante proteína supressora de tumor. A segunda liga-se e seqüestra a pRb, também supressora de tumor, facilitando a liberação de E2F. Apesar do aprimoramento das técnicas de detecção do HPV nas lesões de mucosa oral, o seu envolvimento direto com os carcinomas orais não foi ainda devidamente comprovado, todavia a sua ação sinérgica com outros carcinógenos químicos e físicos, tais como o fumo e o álcool, em determinados carcinomas epidermóides nos parece o caminho mais correto para explicar a ação do papilomavírus humano na carcinogênese oral.

Aggressive, multifocal oral verrucous leukoplakia: proliferative verrucous leukoplakia or not?

BACKGROUND

Some oral verrucal lesions may constitute parts of the clinicopathological spectrum of proliferative verrucous leukoplakia (PVL). Because of its idiopathic yet sinister nature, it is possible that PVL may exist in other populations. The aim of this study was to review the clinicopathological features of persistent, multifocal, oral verrucal lesions in Malaysian population.

METHODS

Patients with multifocal oral verrucal lesions were selected from surgical and histopathological records.

RESULTS

Nine patients of diverse ethnicity with 43 biopsies were reviewed. The mean age at the presentation was 62 years. The most frequent sites affected were gum, sulci, cheek and tongue. Indulgence in risk habits was reported in about 70% of patients. Four cases developed multifocal carcinoma from multifocal leukoplakia.

CONCLUSIONS

In retrospect, none of the cases fulfilled the original PVL criteria, although three cases were suggestive of PVL. Nevertheless, these findings do not necessarily preclude the existence of PVL as a clinicopathological entity in Malaysian population.

Alterations of the P16 gene in uterine cervical carcinoma from Indian patients

In our analysis, alterations in the P16 tumor suppressor gene were seen in 33% (15/46) of sampled uterine cervical lesions. Among the alterations, mutations in P16 were detected in 15% (7/46) of the samples. One mutation occurred at intron 1/exon 2 splice junction. All the other mutations were in exon 2 with three of them as silent mutations. The promoter hypermethylation and homozygous deletion of P16 gene were detected in 6.5% (3/46) and 8.7% (4/46) of the samples respectively. Loss of heterozygosity and microsatellite size alterations at the P16 locus were seen in 17% (8/46) of the samples. HPV16/18 infection was detected in 76% (35/46) of the samples. But no association was found between P16 alterations and HPV infection. Thus, it seems that P16 inactivation may be associated with the development of some uterine cervical carcinoma.

Study of viral integration of HPV-16 in young patients with LSIL

AIMS

To investigate the physical status of human papillomavirus 16 (HPV-16) in low grade squamous intraepithelial lesions (LSILs) as a means of determining the percentage of viral integration.

METHODS

Ninety two LSIL/HPV positive Thin Prep(TM) samples were initially tested for the E6 gene by the polymerase chain reaction (PCR) to identify the HPV-16 virus. To avoid false positive results, the specificity of the bands obtained from PCR was confirmed by Southern blot hybridisation with internal oligonucleotide probes. Next, a PCR screen for the E2 gene was performed to identify those samples in which the virus was integrated. Viral integration was detected in just over half of them.

RESULTS

Twenty of the 92 samples were HPV-16 positive, as shown by PCR for the E6 gene. Southern blot analysis confirmed that 13 of these samples were positive for the viral E6 gene. Thus, viral integration was detected in just over a half of the samples positive for HPV-16.

CONCLUSIONS

These data show that HPV-16 integration occurs in a subset of LSILs. The measurement of HPV-16 integration would be a helpful complementary tool for cytological evaluation in primary cervical screening to identify those patients at risk of developing high grade squamous intraepithelial lesions and cervical cancer.

Alu profiling of primary and metastatic nonsmall cell lung cancer

The metastatic potential of nonsmall cell carcinoma of lung (NSCLC), is currently recognized post factum, when lymph nodes or distant organs are already involved. Our ability to determine which tumors have acquired metastatic potential could help direct therapy to be more aggressive or less aggressive based upon this information. Evaluation of microsatellite instability via detection of LOH at specific loci may be useful in identifying specific markers and/or genes associated with this process. We examined Alu insertional elements as a potential marker of genetic changes associated with the metastatic potential of NSCLC. We analyzed archived, paraffin embedded tissue from 20 proven cases of NSCLC. DNA was extracted from 10 micron paraffin sections and amplified using an Alu PCR protocol. This technique does not examine specific loci but rather results in a banding profile of cellular genomic DNA. Informative allelic banding patterns, noted as differences between primary and metastatic lesions from the same patient, were observed in five of six cases (83%) with intrapulmonary metastases and in only nine of 14 (64%) cases with extrapulmonary metastases. Multiple genomic changes were detected in metastatic tumor cells as compared to normal lung tissue or primary lung tumor tissue. It appears that Alu profiling may be useful in the detection of metastatic vs primary lesions, and this technique may offer a method for identifying novel genes responsible for tumor progression and metastases.

Genetic analysis identifies putative tumor suppressor sites at 2q35-q36.1 and 2q36.3-q37.1 involved in cervical cancer progression

We performed comparative genomic hybridization (CGH) and high-resolution deletion mapping of the long arm of chromosome 2 (2q) in invasive cervical carcinoma (CC). The CGH analyses on 52 CCs identified genetic losses at 2q33-q36, gain of 3q26-q29, and frequent chromosomal amplifications. Characterization of 2q deletions by loss of heterozygosity (LOH) in 60 primary tumors identified two sites of minimal deleted regions at 2q35-q36.1 and 2q36.3-q37.1. To delineate the stage at which these genetic alterations occur in CC progression, we analysed 33 cervical intraepithelial neoplasia (CIN) for LOH. We found that 89% of high-grade (CINII and CINIII) and 40% of low-grade (CINI) CINs exhibited LOH at 2q. To identify the target tumor suppressor gene (TSG), we performed an extensive genetic and epigenetic analyses of a number of candidate genes mapped to the deleted regions. We did not find inactivating mutations in CASP10, BARD1, XRCC5, or PPP1R7 genes mapped to the deleted regions. However, we did find evidence of downregulated gene expression in CFLAR, CASP10 and PPP1R7 in CC cell lines. We also found reactivated gene expression in CC cell lines in vitro after exposure to demethylating and histone deacetylase (HDAC) inhibiting agents. Thus, these data identify frequent chromosomal amplifications in CC, and sites of TSGs at 2q35-q36.1 and 2q36.3-q37.1 that are critical in CC development.

Genetic alterations in the coding region of the bak gene in uterine cervical carcinoma

A significant frequency of mutations (six missense and one silent) was found, for the first time, at the coding region of the bak gene (exons 3, 4 and 6) in 42 carcinomas of the uterine cervix, while no mutations were detected in 32 non-neoplastic cervix tissues. Bak mutations were observed more frequently in the advanced stage and mutated cancer tissues were more resistant to radiotherapy, although trends were not statistically significant because of small sample size.

Deletion mapping using quantitative real-time PCR identifies two distinct 3p21.3 regions affected in most cervical carcinomas

We report chromosome 3p deletion mapping of 32 cervical carcinoma (CC) biopsies using 26 microsatellite markers located in frequently deleted 3p regions to detect loss of heterozygosity and homozygous loss. In addition, two STS markers (NLJ-003 and NL3-001) located in the 3p21.3 telomeric (3p21.3T) and 3p21.3 centromeric (3p21.3C) regions, respectively, were used for quantitative real-time PCR as TaqMan probes. We show that quantitative real-time PCR is reliable and sensitive and allows discriminating between 0, 1 and 2 marker copies per human genome. For the first time, frequent (five of 32 cases, i.e. 15.6%) homozygous deletions were demonstrated in CCs in both 3p21.3T and 3p21.3C regions. The smallest region homozygously deleted in 3p21.3C was located between D3S1568 (CACNA2D2 gene) and D3S4604 (SEMA3F gene) and contains 17 genes previously defined as lung cancer candidate Tumor suppressor genes (TSG(s)). The smallest region homozygously deleted in 3p21.3T was flanked by D3S1298 and NL1-024 (D3S4285), excluding DLEC1 and MYD88 as candidate TSGs involved in cervical carcinogenesis. Overall, this region contains five potential candidates, namely GOLGA4, APRG1, ITGA9, HYA22 and VILL, which need to be analysed. The data showed that aberrations of either NLJ-003 or NL3-001 were detected in 29 cases (90.6%) and most likely have a synergistic effect (P<0.01). The study also demonstrated that aberrations in 3p21.3 were complex and in addition to deletions, may involve gene amplification as well. The results strongly suggest that 3p21.3T and 3p21.3C regions harbor genes involved in the origin and/or development of CCs and imply that those genes might be multiple TSG(s).

Frequent promoter methylation of CDH1, DAPK, RARB, and HIC1 genes in carcinoma of cervix uteri: its relationship to clinical outcome

BACKGROUND

Cervical cancer (CC), a leading cause of cancer-related deaths in women worldwide, has been causally linked to genital human papillomavirus (HPV) infection. Although a host of genetic alterations have been identified, molecular basis of CC development is still poorly understood.

RESULTS

We examined the role of promoter hypermethylation, an epigenetic alteration that is associated with the silencing tumor suppressor genes in human cancer, by studying 16 gene promoters in 90 CC cases. We found a high frequency of promoter methylation in CDH1, DAPK, RARB, and HIC1 genes. Correlation of promoter methylation with clinical characteristics and other genetic changes revealed the following: a) overall promoter methylation was higher in more advanced stage of the disease, b) promoter methylation of RARB and BRCA1 predicted worse prognosis, and c) the HIC1 promoter methylation was frequently seen in association with microsatellite instability. Promoter methylation was associated with gene silencing in CC cell lines. Treatment with methylation or histone deacetylation-inhibiting agents resulted in profound reactivation of gene expression.

CONCLUSIONS

These results may have implications in understanding the underlying epigenetic mechanisms in CC development, provide prognostic indicators, and identify important gene targets for treatment.