PCR-RFLP studies on chromosome 3p in formaldehyde-fixed, paraffin-embedded cervical cancer tissues

Human Papilloma Virus Frequency and Genotypes; Evaluation of the 4879 Screenings Made with Polymerase Chain Reaction and Chip Array Between 2001 and 2019 in Istanbul

Objectives:

The aim of this study is the documentation of human papilloma virus (HPV) frequency and types seen in the city of Istanbul, Turkey, as well as evaluation of the relationship between these subtypes and cytological and pathological diagnoses.

Methods:

4879 cases were studied in our molecular pathology department between 2001 and 2019 in Istanbul. Between 2001 and 2010, 1692 cases were screened for HPV 6, 11, 16, 18, 31, and 33 by conventional hybridization and polymerase chain reaction (PCR). Since 2011, up to 49 HPV typing has been performed for 3187 cases with chip array. The cases were referred to the pathology center and the hospital pathology department by clinicians for screening before HPV vaccination and on the observation of precancerous changes and koilocyts in cytological-histopathological evaluations.

Results:

In this study, the frequency of HPV was found to be 10.8% (527 HPV-positive cases). Among these, 348 cases were high-risk groups, whether or not they were previously associated with a low-risk group. When we look at the distribution of the cases according to the high-risk HPV types, HPV 16 is the most common type. The frequencies of occurrence of other HPV types are as following: HPV–16: 41.7%, HPV–31: 11.7%, HPV–52: 7.9%, HPV–51: 7.1%, HPV–33: 6.9%, HPV–45: 6.5%, HPV–18: 6.3%, HPV–39: 6.1%, and HPV–58: 5.8%. It was further found that multiple infections were 28% of high grade squamous intraepithelial lesion cases. HPV frequency was 38% and 72%, respectively, in cases with cytologically or histopathological precancerous, low-grade squamous intraepithelial lesion, and HSIL changes. As a final note, HPV was detected in 9 of 10 cases with cervical cancer (90%). Only 1 adenocarcinoma case detected in the series was a double infection with HPV types 18 and 45.

Conclusion:

HPV 16 was the most common type found in this study. It is followed by types 31, 52, 51, 33, 45, 18, 39, and 58, respectively. The most common association observed in double infections was between HPV 16 and 58. It was also observed that the incidence of HPV in the city of Istanbul, Turkey, was similar to other developed countries. As a final note, in addition to screening tests, PCR and chip array studies should be conducted and the community should be informed about preventive medicine and the importance of condom use.

Loss of Fhit expression as a potential marker of malignant progression in preinvasive squamous cervical cancer

OBJECTIVE

In a previous study using the same cases of squamous cervical neoplasia and microinvasive carcinoma (MICA) we found an association between FHIT gene deletion and infection with high-risk HPV (HR HPV). The purpose of this study was to evaluate Fhit protein expression by immunohistochemistry in order to determine whether FHIT gene deletion or infection with HR HPV correlated with aberrant protein expression and grade of lesion.

METHODS

A total of 74 archival LLETZ biopsy cases consisting of 23 cervical intraepithelial neoplasia grade 1 (CIN1), 28 CIN3, and 23 MICA cases were selected for Fhit immunostaining. The results of this study on Fhit immunostaining were analyzed in relation to our previous findings using Epi-Info and SPSS-PC statistical analysis software.

RESULTS

Fifty percent (14/28) of CIN3 lesions and 78% (18/23) of MICA lesions had a marked reduction or absence of Fhit protein expression (P = <0.001, strength of association, Cramers' V, 0.632). CIN1 lesions were found to have moderate to strong cytoplasmic expression of Fhit. Seventy percent of cases in this study with reduced/absent Fhit protein expression were also positive for FHIT gene loss of heterozygosity (LOH) (P = 0.04, strength of association, phi, 0.254). A significant statistical relationship was found between Fhit protein expression and HPV 16 infection in combined CIN1, CIN3, and MICA cases (P = <0.001). Eighty-seven percent of cases with reduced/absent Fhit protein expression were positive for HPV 16 (strength of association, phi, 0.552). Ninety percent of HPV 16 and 31 positive cases had reduced/absent Fhit expression.

CONCLUSION

Our findings suggest an association between HPV infection and FHIT gene abnormalities raising the possibility of a mechanistic role for the FHIT gene as a cofactor with HPV in triggering the development of cervical cancer.

Deletion of the FHIT gene in neoplastic and invasive cervical lesions is related to high-risk HPV infection but is independent of histopathological features

The fragile histidine triad (FHIT) gene encompasses the common chromosomal fragile site FRA3B. Human papilloma virus (HPV), which is the main aetiological agent in cervical cancers, has been found to be able to integrate its genes into the chromosome 3 fragile site of cultured cells, deleting a piece of DNA which includes the FHIT gene. Eighty-six microdissected archival cervical LLETZ biopsies comprising cases of cervical intraepithelial neoplasia (CIN) 1 (n=27), CIN3 (n=30) and microinvasive carcinoma (n=29) were evaluated for HPV infection and FHIT gene loss of heterozygosity (LOH). FHIT gene LOH was detected by polymerase chain reaction (PCR) using fluorescently labelled intragenic microsatellite markers D3S1300 and D3S4103. PCR products were analysed on a semi-automated DNA sequencer using Fragment Manager(trade mark) software to determine allele loss. The HPV status of the lesions was determined by PCR using generic and type-specific primers in conjunction with restriction endonuclease digestion. The results were analysed using Epi-Info and SPSS-PC statistical analysis software. Haematoxylin and eosin-stained sections from the 86 cases were profiled for six histopathological features, some of which have been previously shown to be associated with microinvasive cancer. FHIT gene LOH was found in 36% of CIN1 cases, 52% of CIN3 cases and 73% of microinvasive cases (p=0.029). HPV 16 DNA was found in 68% of CIN3 cases and 93% of microinvasive cases (p<0.001). The second most prevalent HPV type found was HPV 31, which was present in only four lesions, three of which had FHIT gene LOH. When FHIT gene LOH was evaluated versus HPV 16 and 31 infection using the chi-square test, a statistically significant relationship was found (p=0.014). FHIT gene LOH was found to be independent of the histopathological features evaluated. The finding of a statistically significant relationship between FHIT gene LOH and oncogenic HPV infection suggests a link between the integration of viral DNA and subsequent gene deletion in the progression of cervical cancer. FHIT gene anomalies may prove to be excellent markers of progression in early uterine cervical cancers.

Analysis of intratumoral heterogeneity of chromosome 3p deletions and genetic evidence of polyclonal origin of cervical squamous carcinoma

Investigation on intratumoral genetic heterogeneity provides an important insight into the roles of genetic alterations in human carcinogenesis and clues to clonal origin of tumors. Intratumoral heterogeneity of genetic changes of cervical cancer has not been described so far. In this study, we analyzed the intratumoral heterogeneity of chromosome 3p deletions and X-chromosome inactivation patterns in multiple microdissected samples from each individual cervical cancer, attempting to understand the roles of 3p deletions in development of cervical cancer and its clonal origin. Totally, 120 normal and lesional samples from 14 cases of fresh cervicalcancers were analyzed. Frequency and patterns of allelic losses of 3p were assessed by polymerase chain reaction (PCR) amplification of 12 microsatellite markers flanking the frequently deleted regions of 3p, followed by Genescan analysis in an ABI 377 DNA sequencer. Loss of heterozygosity was recorded as heterogeneous pattern (LOH present in parts of samples or LOH involving different alleles among different samples) and homogeneous pattern (LOH involving identical alleles in all samples from the tumor). Allelic loss affecting at least one marker was detected in 8 of 14 cases (57%). Allelic losses, both homogeneous and heterogeneous, were frequently detected at FHIT gene region (D3S1300, 40% and 60%; D3S4103, 27.3% and 54.6%), 3p21.3-21.2 (D3S1478, 27.3% and 45.5%), and 3p24.2-22 (D3S1283, 30% and 50%). Seven of eight LOH-positive tumors exhibited homogeneous allelic loss involving at least one of these three 3p loci. Allelic losses were present in the CIN lesions synchronous with invasive lesions positive for LOH. Our findings suggest essential roles of genes on these 3p loci, particularly the FHIT gene in participating in clonal selection and early development of cervical cancer. Most interestingly, with the combination of LOH analysis and X-chromosome inactivation analysis, we provided the first clear genetic evidence of polyclonal origin of cervical invasive cancer in two of eight cases. This finding strongly suggests the importance of field defect (possible human papilloma virus) in cervical carcinogenesis.

Deletion of the FHIT gene in neoplastic and invasive cervical lesions is related to high-risk HPV infection but is independent of histopathological features

The fragile histidine triad (FHIT) gene encompasses the common chromosomal fragile site FRA3B. Human papilloma virus (HPV), which is the main aetiological agent in cervical cancers, has been found to be able to integrate its genes into the chromosome 3 fragile site of cultured cells, deleting a piece of DNA which includes the FHIT gene. Eighty-six microdissected archival cervical LLETZ biopsies comprising cases of cervical intraepithelial neoplasia (CIN) 1 (n=27), CIN3 (n=30) and microinvasive carcinoma (n=29) were evaluated for HPV infection and FHIT gene loss of heterozygosity (LOH). FHIT gene LOH was detected by polymerase chain reaction (PCR) using fluorescently labelled intragenic microsatellite markers D3S1300 and D3S4103. PCR products were analysed on a semi-automated DNA sequencer using Fragment Manager(trade mark) software to determine allele loss. The HPV status of the lesions was determined by PCR using generic and type-specific primers in conjunction with restriction endonuclease digestion. The results were analysed using Epi-Info and SPSS-PC statistical analysis software. Haematoxylin and eosin-stained sections from the 86 cases were profiled for six histopathological features, some of which have been previously shown to be associated with microinvasive cancer. FHIT gene LOH was found in 36% of CIN1 cases, 52% of CIN3 cases and 73% of microinvasive cases (p=0.029). HPV 16 DNA was found in 68% of CIN3 cases and 93% of microinvasive cases (p<0.001). The second most prevalent HPV type found was HPV 31, which was present in only four lesions, three of which had FHIT gene LOH. When FHIT gene LOH was evaluated versus HPV 16 and 31 infection using the chi-square test, a statistically significant relationship was found (p=0.014). FHIT gene LOH was found to be independent of the histopathological features evaluated. The finding of a statistically significant relationship between FHIT gene LOH and oncogenic HPV infection suggests a link between the integration of viral DNA and subsequent gene deletion in the progression of cervical cancer. FHIT gene anomalies may prove to be excellent markers of progression in early uterine cervical cancers.

Loss of heterozygosity among tumor suppressor genes in invasive and in situ carcinoma of the uterine cervix

The aim of the present study was to further clarify the histogenesis of cervical carcinoma by investigating loss of heterozygosity (LOH) among a number of tumor suppressor genes in invasive and in situ carcinoma of the cervix. Materials consisted of 16 in situ and 29 invasive carcinomas (16 squamous cell carcinomas, nine adenocarcinomas, and four adenosquamous carcinomas). DNA samples were collected by microdissection from ordinary formalin-fixed, paraffin-embedded tissues, both from the lesions and from normal tissues. LOH was analyzed using eight DNA polymorphic tumor suppressor markers. Of the 16 cases of carcinoma in situ, three cases exhibited LOH at one locus. Of the 29 cases of invasive carcinomas, six cases exhibited LOH at two loci and nine cases exhibited LOH at one locus. Overall, LOH was found more frequently in invasive carcinomas than in in situ carcinomas. LOH was most frequently detected at the PTCH (Drosophila patched gene) locus. There was no significant correlation between LOH at a specific site and either histologic subtype or clinical stage. These results suggest that LOH might already occur in a fraction of preinvasive squamous lesions and that accumulation of LOH may in part play a role in carcinogenesis of the cervix.

Primary cervical carcinomas show 2 common regions of deletion at 3P, 1 within the FHIT gene: evaluation of allelic imbalance at FHIT, RB1 and TP53 in relation to survival

Chromosome arm 3p is re-arranged in many tumor types, including cervical carcinomas. Putative tumor-suppressor genes on 3p have been proposed, including the FHIT gene, which maps to chromosome band 3p14.2. We have analyzed 79 primary cervical carcinomas for allelic imbalance (AI) at 17 chromosome 3 loci, including 3 within the FHIT gene. Expression of the FHIT gene was evaluated after immunohistochemistry with an antibody against the pFHIT protein. Previously determined human papillomavirus status, defined after in situ hybridization, showed type 16 or 18 in 56/77 tumors. Tumors were also analyzed for AI at loci within the RB1 (chromosome band 13q14.2) and the TP53 (17p13) genes for AI. AI was found at 1 or more 3p loci in 50/79 tumors, at frequencies ranging from 30% to 52% at the individual loci. Two smallest regions of overlapping deletion (SROs) were found, 1 including parts of the FHIT gene (SRO flanked by D3S1481 and D3S1313) and another more distal SRO between D3S32 and D3S1286. FHIT protein expression was reduced in 57/69 (83%) tumors but not associated with AI at FHIT loci (p = 0.56). AI was found in TP53 and RB1 in 18% and 29% of the samples, respectively. Relapse-free survival was associated with AI in the TP53 gene in both a univariate (p = 0.0003) and a multivariate (p = 0.004) analysis. This study confirms a high frequency of AI at chromosome arm 3p in primary cervical carcinomas. The AI results and the reduced FHIT protein staining indicate that FHIT alterations are important in cervical carcinogenesis.

Comparison of chromosome 3p deletions between cervical precancers synchronous with and without invasive cancer

Cervical cancers are considered to originate from a series of pre-malignant lesions (cervical intra-epithelial neoplasia, CIN). The mechanisms behind these events are unknown. In addition to HPV infection, deletions of chromosome 3p have been found to be a frequent event in cervical cancer and likely play an important role in the transition of CIN to invasive cancer. To classify the potential role of 3p deletions in early-stage cervical carcinogenesis, we analyzed LOH of 3p in cervical precancers. Thirty cases with single or multiple CIN lesions were selected for the study, including 20 cases without and 10 cases with synchronous invasive cancers. Allelic losses on 1 or more 3p loci were recorded in 33% (3/9) of CIN II and 36% (5/14) of CIN III lesions from 20 cases without co-existing invasive cancer, whereas an increasing percentage of LOH was observed in the 10 precancerous lesions synchronous with invasive cancer, with 71% (5/7) CIN II and 76% (13/17) CIN III lesions. This result implies that 3p deletions have selective roles in early transition of pre-malignancy to invasive cancer. Comparing the LOH patterns between the 2 groups, genetic deletions in cases with invasive cancers involved extensive regions of 3p but were more localized in precancer cases without concomitant invasive cancer. Two interstitial regions, 3p22-21.3 around marker D3S1260 and 3p21.1 around markers D3S1289 and D3S1076, were most frequently deleted in both groups, suggesting that these 2 regions are novel tumor-suppressor loci which may play a role in early transition of cervical precancer to invasive cancer. Identical LOH patterns between multiple CIN lesions and synchronous invasive cancer in the same case suggests that different cervical precancers and invasive cancer are genetically linked and most likely originate from a single precursor cell.

Fluorescence in situ hybridization in cervical smears: detection of numerical aberrations of chromosomes 7, 3, and X and relationship to HPV infection

BACKGROUND

Human papillomavirus (HPV) is known to play a pivotal role in cervical carcinogenesis. Chromosomal aberrations are known to be related to different biological behaviors of malignant lesions. We analyzed whether numerical chromosomal aberrations, related to more aggressive tumor types, are found not only in high-grade squamous intraepithelial lesions (HSIL) but also in low-grade SIL (LSIL) of the cervix and evaluated their relationship to HPV infection.

METHODS

Eighty women (19 to 74 years of age) were included in this study and grouped according to the Bethesda System: within normal limits (WNL), LSIL, and HSIL. By FISH, chromosomes 7 and X, and in part chromosome 3, were analyzed for numerical aberrations. Using the hybrid capture system HPV detection was performed.

RESULTS

All 20 patients with cervical smear WNL had regular diploid chromosomal pattern and were negative for HPV. Thirteen of the 29 (41.2%) patients with LSIL showed trisomy 7, in association with trisomy X in 4 cases (12.9%). Single trisomy X was detected in 4 cases (12.9%). In 3 of 15 (20%) cases analyzed for chromosome 3 trisomy was observed. Trisomy 3 was associated with trisomy 7 and X or with trisomy 7 alone. The hybrid capture test was performed in 16 patients of this group. Two patients were positive for HPV probe A, 9 for probe B, and 2 for A and B, and 3 patients were negative. Twenty-three of the 29 patients (79.3%) with HSIL showed trisomy 7. Twelve of the 29 patients (41.3%) had an additional trisomy X. Single trisomy X was seen in only 2 cases (6. 9%). Twenty-two patients with HSIL were tested also for chromosome 3. Nine of the 22 patients (40.9%) showed trisomy 3, associated with trisomy 7 or with trisomy 7 and X. In 25 of the 29 patients HPV detection by the hybrid capture system was performed. HPV probe B was positive in 15 cases (60%). One patient was positive for both probes, A and B. Nine (36%) of the patients with HSIL were negative for both HPV probes. No positivity was observed for HPV probe A alone.

CONCLUSION

Our data confirm the pivotal role of HPV in cervical carcinogenesis as it seems to cause changes in the chromosomal pattern of premalignant lesions. Additionally, trisomy 7 may be considered an early event in cervical carcinogenesis, persisting and increasing with progression of the lesion. The roles of trisomy 3 and X need further evaluation.

Comparison of molecular changes in cervical intraepithelial neoplasia in HIV-positive and HIV-indeterminate subjects

OBJECTIVE

HIV infection is associated with an increased incidence of cervical malignancy and its precursor lesions (CIN, cervical intraepithelial neoplasia) compared with the general population. We studied the molecular abnormalities in the development of HIV-associated CIN and compared them with those present in CINs arising in HIV-indeterminate subjects ("sporadic CIN").

METHODS

We investigated the presence of human papilloma virus (HPV) sequences, loss of heterozygosity (LOH), and microsatellite alterations (MAs) at five 3p chromosomal regions using 17 polymorphic markers in precisely microdissected archival tissues from 16 HIV-positive CINs and compared them with those present in 39 sporadic CINs.

RESULTS

HPV sequences were detected in 36 of 55 (66%) CIN lesions, and high-risk oncogenic strains (HPV 16 and 18) accounted for 15 of them. No differences in the HPV frequencies were found between HIV-associated and sporadic CINs. Allelic losses at one or more chromosome 3p regions were frequently detected in CIN lesions (49%). The overall frequency of 3p LOH and the frequencies at all individual regions were similar in HIV-associated and sporadic CINs. The frequency of MA present in the HIV-associated CIN cases (0.093) was sixfold greater than in sporadic CINs (0.014; P = 0.0001). At least 1 MA was present in 11 (69%) of 16 HIV-associated vs. 5 of 39 (13%) sporadic CIN (P = 0.0006). Molecular changes were independent of the presence of HPV sequences.

CONCLUSION

Chromosome 3p deletions are frequently detected in the precursor lesions of cervical carcinoma (CIN) and there are no differences in the 3p LOH frequencies between HIV-associated and sporadic CIN lesions. Microsatellite alterations, which reflect widespread genomic instability, occur at greatly increased frequency in HIV-associated CIN. Although the mechanism underlying the development of increased MAs is unknown, it may play a crucial role in the development of many HIV-associated neoplasias.

The molecular genetics of cervical carcinoma

In the pathogenesis of cervical carcinoma there are three major components, two of them related to the role of human papillomaviruses (HPV). First, the effect of viral E6 and E7 proteins. Second, the integration of viral DNA in chromosomal regions associated with well known tumour phenotypes. Some of these viral integrations occur recurrently at specific chromosomal locations, such as 8q24 and 12q15, both harbouring HPV18 and HPV16. And third, there are other recurrent genetic alterations not linked to HPV. Recurrent losses of heterozygosity (LOH) have been detected in chromosome regions 3p14-22, 4p16, 5p15, 6p21-22, 11q23, 17p13.3 without effect on p53, 18q12-22 and 19q13, all of them suggesting the alteration of putative tumour suppressor genes not yet identified. Recurrent amplification has been mapped to 3q+ arm, with the common region in 3q24-28 in 90% of invasive carcinomas. The mutator phenotype, microsatellite instability, plays a minor role and is detected in only 7% of cervical carcinomas. The development of cervical carcinoma requires the sequential occurrence and selection of several genetic alterations. The identification of the specific genes involved, and their correlation with specific tumour properties and stages could improve the understanding and perhaps the management of cervical carcinoma.

Analysis of FHIT transcripts in cervical and endometrial cancers

Carcinoma of the uterine cervix is a common malignancy, and many affected women, have been found to exhibit loss of heterozygosity (LOH) in the chromosome 3p region. Recent studies have localized the FHIT (fragile histidine triad) gene in this region and also demonstrated a high frequency of abnormalities of this gene in various cancers. To determine the role of the FHIT gene in cervical and uterine carcinomas, 16 cases of cervical carcinoma and 7 cases of endometrial carcinoma, as well as nearby non-cancerous tissues in these patients, were analyzed by reverse transcription of the FHIT mRNA followed by polymerase chain reaction amplification and sequencing of the products. In this study, 13 of 16 cervical cancers and 4 of 7 endometrial cancers displayed abnormal FHIT transcripts, including a lack of 2 or more exons of the FHIT gene, the insertion of several bases in the deletion junctions, and a 282 bp deletion from cDNA 171 to 452, resulting in a frameshift. Moreover, 5 of 16 matched non-cancerous tissues from the cervical cancer patients and 4 of 7 non-cancerous tissues from endometrial cancer patients also showed the presence of abnormal transcripts lacking 3 or more exons of the FHIT gene. Only 1 of 23 paired samples exhibited LOH. Our results suggest that the abnormal transcript of the FHIT gene is common in both normal and tumor tissues of the uterus and cervix. We also checked for HPV infection in these samples and found no definite relationship between the abnormal transcript and human papillomavirus infection.

Loss of heterozygosity in clinical stage IB cervical carcinoma: relationship with clinical and histopathologic features

Loss of heterozygosity (LOH) has been shown to be an important prognostic factor in a variety of malignant neoplasms. The relationship between LOH and established histopathological prognostic factors in cervical carcinoma has not been examined. We studied LOH in 58 FIGO stage IB cervical cancers treated by radical hysterectomy. In a randomly selected subset of 37 of these cases, LOH was examined using markers for all 41 chromosomal arms. Seventy-six percent of the 58 cases and 95% of the extensively studied cases showed LOH at one or more loci. The three most common sites of LOH were 3p21, 6p24-p23, and 11q23.3. In the extensively studied group, LOH on 11q was associated with extensive lymphvascular space invasion (P = .009) and less deeply invasive tumor (P = .042). There was a trend for tumors with LOH on 11q to recur, but this was not statistically significant. No correlation between the presence of LOH on 3p or 6p and lymphvascular space invasion or tumor depth was present. There was no correlation between the number of sites of LOH or between the presence of LOH on 3p, 6p, and 11q and the presence of metastatic tumor in regional lymph nodes, histologic type (squamous v nonsquamous), tumor differentiation, maximum tumor size, degree of inflammation, pattern of invasion, mitotic rate, or clinical recurrence. In summary, tumors with 11q LOH may behave in a more aggressive fashion. Future studies of LOH in cervical carcinoma should include histopathological prognostic information so that the relationship between LOH and these factors can be determined on larger numbers of patients.

Molecular events in uterine cervical cancer

OBJECTIVE

To review the literature regarding the molecular events which occur in the development of uterine cervical cancer, with particular reference to human papillomavirus (HPV) infection.

METHODOLOGY

Bibliographic searches of Medline and the ISI citation databases using appropriate keywords, including the following: papillomavirus, cervix, pathology, cyclin, chromosome, heterozygosity, telomerase, smoking, hormones, HLA, immune response, HIV, HSV, EBV.

CONCLUSIONS

It has become clear that most cervical neoplasia, whether intraepithelial or invasive, is attributable in part to HPV infection. However, HPV infection alone is not sufficient, and, in a small proportion of cases, may not be necessary for malignant transformation. There is increasing evidence that HPV gene products interfere with cell cycle control leading to secondary accumulation of small and large scale genetic abnormalities. This may explain the association of viral persistence with lesion progression but, in many patients, secondary factors, such as smoking and immune response, are clearly important. However, the mechanisms involved in the interaction between HPV and host factors are poorly understood.

Abnormalities of fragile histidine triad genomic and complementary DNAs in cervical cancer: association with human papillomavirus type

BACKGROUND

Chromosome 3p14.2 contains FRA3B, the most active chromosome breakage site in the human genome. The fragile histidine triad (FHIT) gene, a putative tumor suppressor gene, overlaps FRA3B. Human papillomavirus (HPV), a known cofactor in cervical carcinogenesis, can integrate into FRA3B. We examined abnormalities in FHIT and its RNA transcripts in cervical cancer cell lines and tumors. We also investigated the relationship between loss of heterozygosity (LOH) in FHIT/FRA3B and the presence of oncogenic HPV types.

METHODS

Eleven cell lines, 40 tumors (20 fresh and 20 archival), and 10 normal cervical epithelia were examined. Two intragenic polymorphic markers (D3S1300 and D3S4103) and the polymerase chain reaction (PCR) were used to examine FHIT LOH. Reverse transcription-PCR (RT-PCR) analysis and single-strand conformation polymorphism analysis of RT-PCR products were used to characterize FHIT transcripts. Oncogenic HPV types were identified by PCR, using general and type-specific primers.

RESULTS

All normal epithelia, 19 of 20 fresh tumors and nine of 11 cell lines expressed wild-type and, occasionally, exon 8-deleted FHIT transcripts. Additional aberrant FHIT transcripts were seen in nine of 20 fresh tumors and in seven of 11 cell lines. DNA sequencing of the aberrant transcripts revealed a variety of insertions and deletions but no point mutations. Three cell lines also had homozygous FHIT deletions. Oncogenic HPV types (i.e., 16, 18, 31, and 33) were detected in 18 of 20 archival tumors, and, in these tumors, LOH within FHIT was identified in nine of 16 informative cases. HPV 16 was found to be associated with LOH in the FHIT/FRA3B region (P = .041).

CONCLUSION

FHIT/FRA3B is frequently altered in cervical cancer, demonstrating LOH, occasional homozygous deletions, and frequent aberrant transcripts not found in normal epithelia. However, the presence of wild-type transcripts and the lack of protein-altering point mutations raise questions about FHIT's function as a classic tumor suppressor gene in cervical tissue.

Loss of heterozygosity for defined regions on chromosomes 3, 11 and 17 in carcinomas of the uterine cervix

Loss of heterozygosity (LOH) frequently occurs in squamous cell carcinomas of the uterine cervix and indicates the probable sites of tumour-suppressor genes that play a role in the development of this tumour. To define the localization of these tumour-suppressor genes, we studied loss of heterozygosity in 64 invasive cervical carcinomas (stage IB and IIA) using the polymerase chain reaction with 24 primers for polymorphic repeats of known chromosomal localization. Chromosomes 3, 11, 13, 16 and 17, in particular, were studied. LOH was frequently found on chromosome 11, in particular at 11q22 (46%) and 11q23.3 (43%). LOH on chromosome 11p was not frequent. On chromosome 17p13.3, a marker (D17S513) distal to p53 showed 38% LOH, whereas p53 itself showed only 20% LOH. On the short arm of chromosome 3, LOH was frequently found (41%) at 3p21.1. The beta-catenin gene is located in this chromosomal region. Therefore, expression of beta-catenin protein was studied in 39 cases using immunohistochemistry. Staining of beta-catenin at the plasma membrane of tumour cells was present in 38 cases and completely absent in only one case. The tumour-suppressor gene on chromosome 3p21.1 may be beta-catenin in this one case, but (an)other tumour-suppressor gene(s) must also be present in this region. For the other chromosomes studied, 13q (BRCA-2) and 16q (E-cadherin), only sporadic losses (< 15% of cases) were found. Expression of E-cadherin was found in all of 37 cases but in six cases the staining was very weak. No correlation was found between clinical and histological parameters and losses on chromosome 3p, 11q and 17p. In addition to LOH, microsatellite instability was found in one tumour for almost all loci and in eight tumours for one to three loci. In conclusion, we have identified three loci with frequent LOH, which may harbour new tumour-suppressor genes, and found microsatellite instability in 14% of cervical carcinomas.

Genomic deletion and p53 inactivation in cervical carcinoma

The tumor-suppressor gene p53 acts as "the guardian of the genome", sensing DNA damage and initiating protective responses. To examine the hypothesis that p53 abnormality leads to increased genomic alterations in primary tumor cells, our study utilized 51 primary tumors of cervical carcinoma and 10 microsatellite markers. These markers were mapped to the short arms of chromosomes 3 and 5, covering the regions 3p13-25 and 5p15.1-15.3. Genomic deletion on 3p and 5p was correlated with genetic or epigenetic p53 inactivation pathways, including p53 mutation, genetic deletion of p53 and cervical infection with human papillomavirus. The proportion of abnormal p53 was found to be significantly higher in the cases exhibiting loss of heterozygosity (LOH) on 5p (p < 0.001), supporting the hypothesis of the presence of a p53-dependent pathway to cervical tumorigenesis. In contrast, however, LOH on 3p was found to be independent of p53 inactivation. A common deletion region, 3p22-24, was identified in 44% of informative cases, and genomic loss at this specific region was correlated with early tumorigenic onset and poor grade of tumor differentiation. Diversity within the patterns of genomic alteration in the same form of cancer suggests different sets of risk/tumorigenic profiles, molecular pathogenesis, as well as prognosis and outcome.

Specific chromosomal imbalances in human papillomavirus-transfected cells during progression toward immortality

High risk human papillomaviruses (HPVs) known to be closely associated with cervical cancer, such as HPV16 and HPV18, have the potential to immortalize human epithelial cells in culture. Four lines of HPV-transfected keratinocytes were analyzed by comparative genomic hybridization at different time points after transfection. A number of chromosomal imbalances was found to be highly characteristic for the cultures progressing toward immortality. Whereas several of these were new and previously not found as recurrent aberrations in cervical tumors, some were identical to chromosomal changes observed during cervical carcinogenesis. The data put new emphasis on the studied cell system as a relevant model for HPV-induced pathogenesis.

Chromosomal abnormalities in cutaneous T-cell lymphoma and in its premalignant conditions as detected by G-banding and interphase cytogenetic methods

The etiology of cutaneous T-cell lymphomas (CTCL) is unknown. We studied the pattern of chromosomal abnormalities with G-banding and interphase in situ hybridization methods in blood mononuclear cells in 17 patients representing the different phases of CTCL or the premalignant condition, parapsoriasis en plaque, and in 10 control persons. We used biotinylated centromere-specific probes with fluorescent detection (FISH) for chromosomes 1, 11, 8, and 17 and similar, enzymatically detectable, digoxigenin-labeled probes for chromosomes 1, 6, 12, 17, and 18. In G-banding, all patients showed numerical and structural chromosome aberrations. Numerical aberrations of chromosomes 6, 13, 15, and 17, marker chromosomes, and structural aberrations of chromosomes 3, 9, and 13 were increased in mycosis fungoides (MF) compared with healthy controls. In four of five patients the detection of a chromosomal clone preceded relapse or progression of the disease. In FISH of interphase cells, the cells abnormal for chromosomes 8 or 11, and for all four chromosomes collectively, were increased in MF and in Sezary Syndrome (SS). FISH and G-banding methods agreed statistically significantly for the detection of monosomy. Also, digoxigenin-labeled probes hybridized to interphases or mitoses detected aberrations corresponding to those observed with G-banding. Thus, chromosomally abnormal cells can be found in the peripheral blood of both parapsoriasis en plaque and CTCL patients. They can be detected with interphase cytogenetical methods, which obviates the need for dividing cells, often difficult to accomplish in CTCL.

Deletions of the short arm of chromosome 3 in solid tumors and the search for suppressor genes

The concept that cells can become malignant upon the elimination of parts of chromosomes inhibiting cell division dates back to Boveri in 1914. Deletions occurring in tumor cells are therefore considered a first indication of possible locations of tumor suppressor gene. Approaches used to localize and identify the paradigm of tumor suppressors, RB1, have also been applied to localize tumor suppressor genes on 3p, the short arm of chromosome 3. This review discusses the methodological advantages and limitations of the various approaches. From a review of the literature on losses of 3p in different types of solid tumors it appears that some tumor types show involvement of the same region, while between others the regions involved clearly differ. Also discussed are results of functional assays of tumor suppression by transfer of part of chromosome 3 into tumor cell lines. The likelihood that a common region of deletions would contain a tumor suppressor is strongly enhanced by coincidence of that region with a chromosome fragment suppressing tumorigenicity upon introduction in tumor cells. Such a situation exists for a region in 3p21.3 as well as for one or more in 3p12-p14. The former region is considered the location of a lung cancer suppressor. The same gene or a different one in the same region may also play a role in the development of other cancers including renal cell cancer. In the latter cancer, there may be additional roles of the VHL region and/or a 3p12-p14 region. The breakpoint region of a t(3;8) originally found to be constitutively present in a family with hereditary renal cell cancer now seems to be excluded from such a role. Specific genes on 3p have been suggested to act as suppressor genes based on either their location in a common deletion region, a markedly reduced expression or presence of aberrant transcripts, their capacity to suppress tumorigenicity upon transfection in to tumor cells, the presumed function of the gene product, or a combination of several of these criteria. A number of genes are evaluated for their possible role as a tumor suppressor according to these criteria. General agreement on such a role seems to exist only for VHL. Though hMLH1 plays an obvious role in the development of specific mismatch repair-deficient cancers, it cannot revert the tumor phenotype and therefore cannot be considered a proper tumor suppressor. The involvement of VHL and MLH1 also in some specific hereditary cancers allowed to successfully apply linkage analysis for their localization. TGFBR2 might well have a tumor suppressor function. It does reduce tumorigenicity upon transfection. Other 3p genes coding for receptor proteins THRB and RARB, are unlikely candidates for tumor suppression. Present observations on a possible association of FHIT with tumor development leave a number of questions unanswered, so that provisionally it cannot be considered a tumor suppressor. Regions that have been identified as crucial in solid tumor development appear to be at the edge of synteny blocks that have been rearranged through the chromosome evolution which led to the formation of human chromosome 3. Although this may merely represent a chance occurrence, it might also reflect areas of genomic instability.

Presence of human papillomavirus in squamous cell laryngeal carcinomas. A study of thirty-nine cases using polymerase chain reaction and in situ hybridization

Human papillomavirus (HPV) has a well-established association with benign and malignant cervical tumours as well as with laryngeal papillomas, while its association with laryngeal carcinomas is still controversial. We have examined 39 squamous cell carcinomas of the larynx for HPV using PCR with three consensus primers (Cp, My 09/11 and Gp 5+/6+). Specimens positive for consensus primers were examined with specific PCR primers for HPV 6, 11, 16, 18, 31, 33 and 35 and with in situ hybridization (ISH). Three samples (8%) were found HPV positive for two or three consensus primers. One case was confirmed to be HPV 16 with both PCR and ISH. The findings of both a punctate and diffuse signal with the use of ISH indicated HPV to be in both integrated and episomal form. For the other two HPV positive specimens, the examination indicated a type related to HPV 6/11, but it could not be determined with certainty. This study strongly indicates that HPV 16 is associated with some squamous cell laryngeal carcinomas. The possibility of association with other HPV types or mutants of these needs further investigation.

Molecular cytogenetic analysis of five newly established cervical cancer cell lines using G banding and fluorescence in situ hybridization

Cervical tumors nearly all have complex karyotypes and more precise cytogenetic information is required to establish whether specific rearrangements occur, and if they are related to the type of HPV infection found. The karyotypes of five recently established cervical cancer cell lines, three from squamous cell carcinomas (two HPV 16 +ve and one HPV 18 +ve), one from an adenocarcinoma (HPV -ve), and one from an adenosquamous carcinoma (HPV 16 +ve), have been analysed using fluorescence in situ hybridization (FISH), with 23 chromosome specific paints, YACs and cosmids as probes, in addition to conventional G banding, in order to identify markers and clarify the breakpoints. Chromosomes 1 and 3 were rearranged in all cell lines. Breakpoints in the squamous lines were all in 3q. but in different regions. Small metacentrics involving chromosome 5 were a del(5q) in one line, and a t(X;5) in another, rather than i(5p). The region 6q21 was involved in three cases and chromosome 9 was rearranged in four. An i(8q) was found in three squamous carcinoma cell lines. Structural changes of 11q were found only in two cases, but a marker 11 representing amplification in the 11q14-22 region was duplicated in the adenosquamous line.

Human papilloma virus has no prognostic significance in cervical carcinoma

The prognostic significance of the detection of HPV (human papilloma virus) DNA in cervical carcinoma was evaluated in 223 cases treated from January 1988 to November 1989. HPV DNA was detected by PCR (polymerase chain reaction) on fresh tumour specimens obtained before therapy was started. HPV DNA of any type was detected in 93.3% of all tumours, HPV16 was the predominant type and was detected in 69% of cases. HPV18 was more frequent in adeno- and adenosquamous carcinoma than in squamous cell carcinoma and occurred more often in poorly differentiated tumours than in more highly differentiated tumours. Patients with HPV negative tumours were on average older than patients with tumours containing HPV. Neither presence of HPV DNA nor HPV type had prognostic significance. In 63 women with early stage tumours submitted to surgery, no difference was found in the frequency of lymph node metastasis, vessel invasion or prognosis related to HPV type. We conclude that neither the presence nor the type of HPV DNA had any prognostic significance in cervical carcinoma.

Simultaneous assessment of loss of heterozygosity at multiple microsatellite loci using semi-automated fluorescence-based detection: subregional mapping of chromosome 4 in cervical carcinoma

Detection of loss of heterozygosity (LOH) by comparison of normal and tumor genotypes using PCR-based microsatellite loci provides considerable advantages over traditional Southern blotting-based approaches. However, current methodologies are limited by several factors, including the numbers of loci that can be evaluated for LOH in a single experiment, the discrimination of true alleles versus "stutter bands," and the use of radionucleotides in detecting PCR products. Here we describe methods for high throughput simultaneous assessment of LOH at multiple loci in human tumors; these methods rely on the detection of amplified microsatellite loci by fluorescence-based DNA sequencing technology. Data generated by this approach are processed by several computer software programs that enable the automated linear quantitation and calculation of allelic ratios, allowing rapid ascertainment of LOH. As a test of this approach, genotypes at a series of loci on chromosome 4 were determined for 58 carcinomas of the uterine cervix. The results underscore the efficacy, sensitivity, and remarkable reproducibility of this approach to LOH detection and provide subchromosomal localization of two regions of chromosome 4 commonly altered in cervical tumors.

High incidence of human papillomavirus in 146 cervical carcinomas. A study using three different pairs of consensus primers, and detecting viral genomes with putative deletions

Polymerase chain reaction (PCR) primer sets and probe-cocktails were used for human papillomavirus (HPV) detection and typing of 146 fresh frozen biopsies of cervical carcinoma. We obtained a high detection rate (96%) by using three sets of consensus primer pairs directed at the L1 and E1 regions of HPV and by probing with a cocktail of random-labelled consensus and type-specific PCR products derived from HPV plasmids. In addition, we performed type-specific PCR amplification with E6-E7 primers. The procedure was designed to detect all HPV-positive cases in a rapid, sensitive and specific way. In addition, by using different regions for amplification, we detected cases with putative genomic deletions in HPV. All the negative PCR and DNA isolation controls were negative. The six negative samples were negative with all probe-cocktails and type-specific primers and three of these negative samples were clear cell carcinomas. The detection rate was similar in squamous carcinomas and in adenocarcinomas and type 16 was most common (65%) in both types of carcinoma. There were no double infections of human papillomavirus 16 and 18.