Genetic alterations during the progression of squamous cell carcinomas of the uterine cervix

Prevalence of HER2 overexpression and amplification in cervical cancer: A systematic review and meta-analysis

The reported rates of HER2 positivity in cervical cancer (CC) range from 0% to 87%. The importance of HER2 as an actionable target in CC would depend on HER2 positivity prevalence. Our aim was to provide precise estimates of HER2 overexpression and amplification in CC, globally and by relevant subgroups. We conducted a PRISMA compliant meta-analytic systematic review. We searched Medline, EMBASE, Cochrane database, and grey literature for articles reporting the proportion of HER2 positivity in CC. Studies assessing HER2 status by immunohistochemistry or in situ hybridization in invasive disease were eligible. We performed descriptive analyses of all 65 included studies. Out of these, we selected 26 studies that used standardized American Society of Clinical Oncology / College of American Pathologists (ASCO/CAP) Guidelines compliant methodology. We conducted several meta-analyses of proportions to estimate the pooled prevalence of HER2 positivity and subgroup analyses using geographic region, histology, tumor stage, primary antibody brand, study size, and publication year as moderators. The estimated pooled prevalence of HER2 overexpression was 5.7% (CI 95%: 1.5% to 11.7%) I2 = 87% in ASCO/CAP compliant studies and 27.0%, (CI 95%: 19.9% to 34.8%) I2 = 96% in ASCO/CAP non-compliant ones, p < 0.001. The estimated pooled prevalence of HER2 amplification was 1.2% (CI 95%: 0.0% to 5.8%) I2 = 0% and 24.9% (CI 95%: 12.6% to 39.6%) I2 = 86%, respectively, p = 0.004. No other factor was significantly associated with HER2 positivity rates. Our results suggest that a small, but still meaningful proportion of CC is expected to be HER2-positive. High heterogeneity was the main limitation of the study. Variations in previously reported HER2 positivity rates are mainly related to methodological issues.

HPV-16/18 E6-induced APOBEC3B expression associates with proliferation of cervical cancer cells and hypomethylation of Cyclin D1

Oncogenic high-risk human papillomavirus (HR-HPV) infection causes a majority of cases of cervical cancer and pre-cancerous cervical lesions. However, the mechanisms underlying the direct evolution from HPV-16/18-infected epithelium to cervical intraepithelial neoplasia (CIN) III, which can progress to cervical cancer, remain poorly identified. Here, we performed RNA-seq after laser capture microdissection, and found that APOBEC3B was highly expressed in cervical cancer specimens compared with CIN III with HPV-16/18 infection. Furthermore, immunohistochemical analysis confirmed that high levels of APOBEC3B were correlated with lymph node metastasis in cervical cancer. Subsequent experiments revealed that HPV-16 E6 could upregulate APOBEC3B through direct binding to the promoter of APOBEC3B in cervical cancer cells. Silencing of APOBEC3B by stable short hairpin RNA-mediated knockdown reduced the proliferative capacity of Caski and HeLa cells in vitro and in vivo, but had only a small effect on the migration and invasion of two cervical cancer cell lines. Finally, we identified the changes in gene expression following APOBEC3B silencing in Caski cells by microarray, demonstrating a biological link between APOBEC3B and CCND1 in cervical cancer cells. Importantly, through methyl-capture sequencing and pyrosequencing, APOBEC3B was found to affect the levels of the downstream protein Cyclin D1 (which is encoded by the CCND1 gene) through hypomethylation of the CCND1 promoter. In conclusion, our study supports HPV-16 E6-induced APOBEC3B expression associates with proliferation of cervical cancer cells and hypomethylation of Cyclin D1. Thus, APOBEC3B may be a potential therapeutic target in human cervical cancer.

HPV16 E6 promotes cervical cancer cell migration and invasion by downregulation of NHERF1

HPV16 is the predominant type of HPV causing invasive cervical cancer. However, the underlying molecular mechanism of the unparalleled carcinogenic power of HPV16 compared to other types of high-risk (HR)-HPV including HPV18 remains elusive. The PDZ binding motif (PBM) of high-risk HPV E6 plays an important role in neoplasia and progression of cervical cancer. HPV16 E6 rather than HPV18 E6, interacted with NHERF1 by its PBM region, and induced degradation of NHERF1. NHERF1 retarded the assembly of cytoskeleton by downregulation of ACTN4, thereby inhibited the migration and invasion of cervical cancer cells in both cell and mouse model. HPV16 E6 was confirmed to enhance actin polymerization with increased ACTN4 level by downregulation of NHERF1, and result in enhanced migration and invasion of cervical cancer cells. GSEA analysis of cervical cancer specimens also showed that HPV16 E6 rather than HPV18 E6, was significantly associated with actin cytoskeleton assembly. That downregulation of NHERF1 by HPV16 E6 promoted cytoskeleton assembly and cell invasion, was an important cause in cervical cancer carcinogenesis. These findings provided the differential mechanism between HPV16 E6 and HPV18 E6 in the development and progression of cervical cancer, which may partially explain the differences of carcinogenic power between these two types of HR-HPVs.

Gene expression analysis combined with functional genomics approach identifies ITIH5 as tumor suppressor gene in cervical carcinogenesis

Progression from human papillomavirus-induced premalignant cervical intraepithelial neoplasia (CIN) to cervical cancer (CC) is driven by genetic and epigenetic events. Our microarray-based expression study has previously shown that inter-α-trypsin-inhibitor heavy chain 5 (ITIH5) mRNA levels in CCs were significantly lower than in high-grade precursor lesions (CIN3s). Therefore, we aimed to analyze in depth ITIH5 expression during cervical carcinogenesis in biopsy material and cell culture. Moreover, functional analyses were performed by ectopic expression of ITIH5 in different cell lines. We were able to confirm the validity of our microarray differential expression data by qPCR, demonstrating a clear ITIH5 downregulation in CC as compared with CIN2/3 or normal cervix. ITIH5 protein loss, evaluated by immunohistochemistry, was evident in 81% of CCs, whereas ITIH5 showed weak to moderate cytoplasmic staining in 91% of CIN2/3 cases. In addition, ITIH5 was strongly reduced or absent in seven CC cell lines and in three immortalized keratinocyte cell lines. Moreover, ITIH5 mRNA loss was associated with ITIH5 promoter methylation. ITIH5 expression could be restored in CC cell lines by pharmacological induction of DNA demethylation and histone acetylation. Functionally, ITIH5 overexpression significantly suppressed proliferation of SW756 cells and further resulted in a significant reduction of colony formation and cell migration in both CaSki and SW756 tumor models, but had no effect on invasion. Remarkably, ITIH5 overexpression did not influence the phenotype of HeLa cells. Taken together, ITIH5 gene silencing is a frequent event during disease progression, thereby providing evidence for a tumor suppressive role in cervical carcinogenesis.

Assessment of the frequency of genetic alterations (LOH/MSI) in patients with intraepithelial cervical lesions with HPV infection: a pilot study

In the present study, we analyzed (1) the type of HPV infection and (2) the frequency of loss of heterozygosity and microsatellite imbalance (LOH/MSI) in normal cytology and cervical intraepithelial neoplasia (CIN1-3). The cytological material included: low-grade squamous intraepithelial lesions (CIN1, n = 11), high-grade lesions (CIN2 and CIN3, n = 13), and cytologically normal cells from non-neoplastic cervical samples (n = 8). HPV genotyping was done using RealLine HPV 16/18 kit. We used 20 microsatellite markers from: 1p31.2, 3p14.3, 3p21.3, 3p22.2, 3p24.2, 3p25.3, 7q32.2, 9p21.3, 11p15.5, 12q23.2, and 16q22.1. LOH/MSI was correlated with clinicopathological parameters. The presence of HPV DNA was revealed in 78.13 % samples, including normal cytology. LOH/MSI was the most frequent for: 3p25.3 (39 %), 3p22.2 (20.83 %), 3p24.2 (20 %), and 3p14.3 (16.67 %). It was demonstrated that D3S1234 (FHIT; 3p14.3), D3S1611 (MLH1; 3p22.2), D3S1583 (RARB; 3p24.2), D3S1317 and D3S3611 (VHL; 3p25.3) could differentiate patients with CIN2/CIN3 versus CIN1, showing significantly higher frequency in CIN2/CIN3. LOH/MSI frequency for other than 3p markers was lower, 10-22.2 %. The simultaneous occurrence of LOH/MSI for several markers (OFAL) was higher in CIN2/CIN3. Significant differences in OFAL were found between samples with versus without HPV infection. In HPV-positive patients, significant differences in OFAL were found between normal cytology, CIN1 and CIN2/CIN3. HPV infection influences the increase in LOH/MSI frequency, especially in tumor suppressor gene loci. Several studied microsatellite markers seem to be useful for CIN grading. Hopefully, the obtained results, if confirmed on larger patient cohort, would allow creating a panel of markers supporting clinical diagnosis in patients with HPV infection.

Microchimeric Cells, Sex Chromosome Aneuploidies and Cancer

The phenomenon of feta-maternal microchimerisms inspires numerous questions. Many questions remain to be answered regarding this new avenue of genetics. The X and Y chromosomes have been associated with malignancy in different types of human tumors. We aimed to investigate the numerical aberrations of chromosomes X and Y in lung cancer (LC) and bladder cancer (BC) and review recent evidence for possible roles of microchimeric cells (McCs) in these cancers. We carried out cytogenetic analysis of the tumor and blood sampling in 52 cases of people with BC and LC, and also with 30 healthy people. A total of 48 (92.3 %) of the patients revealed sex chromosome aneuploidies (SCAs). A total SCAs was found in 9.8 % of 2282 cells that were analyzed as one or more cells in each case. The 68 and 95 SCAs were found in the 1952 (8.4 %) cells in peripheral blood, and 41 and 19 SCAs in the 330 (18.2 %) cells in the tumoral tissues respectively. There was a significant difference in the frequencies of SCAs between the patients and the control groups determined by the Fischer's Exact Test (p < 0.0001). The frequencies of SCAs were higher in the tumoral tissues than in the blood (p < 0.0001). There was a significant difference in the frequencies of SCAs between the tumor and blood tissues, and this was higher in the tumor tissue (p < 0.0001). In general, 78.9 % (41) of the 52 patients with LC and BC had X and Y chromosome monosomies. Largely a Y chromosome loss was present in 77.8 % of the men, and the 47, XXY karyotype was found in 33.3 % of them. The second most common SCA was monosomy X, and was found in 71.4 % of the women. McCs were observed in 26.9 % of the 52 patients, and the frequencies of McCs were higher in the blood than in the tissues (p < 0.0001). XY cells were identified in the lung and bladder tissues of the women who had been pregnant with boys, but not in those who had not. There was a significant difference in the frequencies of McCs between the LC and BC patients (p < 0.0005). We speculate that the microchimerism could have a general beneficial role in cancer, in which some sites may not be evident because of an allogeneic maternal immune reaction that hastens cancer development. A further understanding of McCs may help in anticipating its implications in cancer. Our results may suggest that SCAs may be contributing factors in the development of LC and BC, and aneuploidies of X and Y chromosomes play a role in the pathogenesis of cancers.

Detection of hTERC and c-MYC genes in cervical epithelial exfoliated cells for cervical cancer screening

Cervical cancer is the principal cause of mortality due to cancer in women worldwide. New predictive markers may increase survival rates by improving the treatment of patients at a high risk for cancer. This study was carried out to investigate the amplification of human telomerase RNA component (hTERC) or/and c-MYC in cervical epithelial exfoliated cells for cervical carcinoma screening. We collected 171 specimens. including speciments from normal cervix, benign lesions, cervical intraepithelial neoplasia (CIN)1, CIN2 and CIN3, or carcinoma in situ, as well as invasive cervical squamous cell carcinoma. Fluorescence in situ hybridization (FISH) was performed to detect alterations in hTERC and c-MYC expression. We analyzed the area under the receiver operating characteristic (ROC) curve (AUC), as well as the sensitivity and specificity of single screening and conjoined screening. There was a trend toward an increasing amplification of 2 genes with the increasing severity of cervical lesions. ROC curve analysis demonstrated that the AUC values of the hTERC gene for the screening of different cervical lesions were >0.8. Compared with the hTERC gene, the AUC of the c-MYC gene for the screening of ≥CIN3 was >0.8 and the AUC for the screening of other cervical lesions was >0.7. For the screening of cervical lesions above the grade of benign lesions, cytological diagnosis was superior to the gene detection with significant differences. For the screening of cervical lesions >CIN1, there were no statistically significant differences (P>0.05) between the hTERC gene and cytological diagnosis, whereas the screening results of c-MYC detection and cytological diagnosis differed significantly (P<0.05). For the screening of cervical lesions >CIN2 or >CIN3, the detection of hTERC and c-MYC genes and cytological diagnosis had similar screening results with no statistically significant differences (P>0.05). In conclusion, using FISH to detect the amplification of hTERC or/and c-MYC on cervical epithelial exfoliated cells may be a useful and specific screening method for precancerous lesions.

ATL

Objective

To investigate the clinical significance of abnormal human telomerase RNA gene component (hTERC) gene amplification tested by fluorescence in situ hybridization in cervical lesions.

Methods

In 373 patients with cytologic abnormalities, high-risk human papilomavirus (HR-HPV) was detected by the hybrid capture II method, and abnormal amplification of the hTERC gene in exfoliated cells was detected by fluorescence in situ hybridization.

Results

Cell smear findings suggested atypical squamous cells in 148 patients, low-grade squamous intraepithelial lesion in 62 patients, and high-grade squamous intraepithelial lesion in 107 patients, squamous cell carcinoma in 56 patients, and cervical biopsy-revealed inflammation in 89 patients, cervical intraepithelial neoplasia (CIN) I in 36 patients, CIN II in 43 patients, CIN III in 129 patients, and infiltrating carcinoma in 76 patients. In the inflammation, CIN I, CIN II, CIN III, and infiltrating carcinoma groups, the infection rates of HR-HPV were 29.21%, 52.78%, 74.42%, 92.25%, and 93.42% (P < 0.01), respectively; the positive rates of hTERC gene amplification were 0.00%, 13.89%, 41.86%, 78.29%, and 89.47% (P < 0.01), respectively. With respect to advanced cervical lesions (≥CIN II), cytology (≥ low-grade squamous intraepithelial lesion), HR-HPV testing, and hTERC testing differed insignificantly in the negative predictive value (P > 0.05), but they differed significantly in the sensitivity, specificity, and positive predictive value (P < 0.01). Among the 3 methods, hTERC testing showed the highest specificity and positive predictive value, and HR-HPV testing showed the highest sensitivity. In 41 patients with untreated CIN I and CIN II, the sensitivity of detection of hTERC gene amplification to predict lesion progression was 88.89%, and the specificity was 93.75%.

Conclusion

Detection of abnormal amplification of the hTERC gene can assist in screening cervical lesions and identifying CIN I/II patients with a high progression risk.

Epigenetic variability in cells of normal cytology is associated with the risk of future morphological transformation

Background

Recently, it has been proposed that epigenetic variation may contribute to the risk of complex genetic diseases like cancer. We aimed to demonstrate that epigenetic changes in normal cells, collected years in advance of the first signs of morphological transformation, can predict the risk of such transformation.

Methods

We analyzed DNA methylation (DNAm) profiles of over 27,000 CpGs in cytologically normal cells of the uterine cervix from 152 women in a prospective nested case-control study. We used statistics based on differential variability to identify CpGs associated with the risk of transformation and a novel statistical algorithm called EVORA (Epigenetic Variable Outliers for Risk prediction Analysis) to make predictions.

Results

We observed many CpGs that were differentially variable between women who developed a non-invasive cervical neoplasia within 3 years of sample collection and those that remained disease-free. These CpGs exhibited heterogeneous outlier methylation profiles and overlapped strongly with CpGs undergoing age-associated DNA methylation changes in normal tissue. Using EVORA, we demonstrate that the risk of cervical neoplasia can be predicted in blind test sets (AUC = 0.66 (0.58 to 0.75)), and that assessment of DNAm variability allows more reliable identification of risk-associated CpGs than statistics based on differences in mean methylation levels. In independent data, EVORA showed high sensitivity and specificity to detect pre-invasive neoplasia and cervical cancer (AUC = 0.93 (0.86 to 1) and AUC = 1, respectively).

Conclusions

We demonstrate that the risk of neoplastic transformation can be predicted from DNA methylation profiles in the morphologically normal cell of origin of an epithelial cancer. Having profiled only 0.1% of CpGs in the human genome, studies of wider coverage are likely to yield improved predictive and diagnostic models with the accuracy needed for clinical application.

Trial registration

The ARTISTIC trial is registered with the International Standard Randomised Controlled Trial Number ISRCTN25417821.

HPV type-related chromosomal profiles in high-grade cervical intraepithelial neoplasia

Background

The development of cervical cancer and its high-grade precursor lesions (Cervical Intraepithelial Neoplasia grade 2/3 [CIN2/3]) result from a persistent infection with high-risk human papillomavirus (hrHPV) types and the accumulation of (epi)genetic host cell aberrations. Epidemiological studies have demonstrated variable CIN2/3 and cancer risks between different hrHPV types. Recent genomic profiling studies revealed substantial heterogeneity in the chromosomal aberrations detected in morphologically indistinguishable CIN2/3 suggestive of varying cancer risk. The current study aimed to investigate whether CIN2/3 with different hrHPV types vary with respect to their chromosomal profiles, both in terms of the number of aberrations and chromosomal loci affected.

Methods

Chromosomal profiles were determined of 43 p16^INK4a-immunopositive CIN2/3 of women with long-term hrHPV infection (≥ 5 years). Sixteen lesions harboured HPV16, 3 HPV18, 14 HPV31, 1 HPV33, 4 HPV45, 1 HPV51, 2 HPV52 and 2 HPV58.

Results

Unsupervised hierarchical clustering analysis of the chromosomal profiles revealed two major clusters, characterised by either few or multiple chromosomal aberrations, respectively. A majority of 87.5% of lesions with HPV16 were in the cluster with relatively few aberrations, whereas no such unbalanced distribution was seen for lesions harbouring other hrHPV types. Analysis of the two most prevalent types (HPV16 and HPV31) in this data set revealed a three-fold increase in the number of losses in lesions with HPV31 compared to HPV16-positive lesions. In particular, losses at chromosomes 2q, 4p, 4q, 6p, 6q, 8q & 17p and gain at 1p & 1q were significantly more frequent in HPV31-positive lesions (FDR < 0.2).

Conclusions

Chromosomal aberrations in CIN2/3 are at least in part related to the hrHPV type present. The relatively low number of chromosomal aberrations observed in HPV16-positive CIN2/3 suggests that the development of these lesions is less dependent on genetic insult than those caused by other types like HPV31.

Allelic loss of 6q25-27, the PARKIN tumor suppressor gene locus, in cervical carcinoma

Studies on loss of heterozygosity have been made for Parkin gene-specific microsatellite markers in malignancies like breast, ovary and lungs, and the results have shown a significant association. However, till date, there is no study with respect to Parkin gene-associated microsatellite markers in cervical cancer. The present study deals with the Parkin gene-associated microsatellite markers and the occurrence of its loss of heterozygosity in patients with human cervical cancer. DNA was isolated from the 105 cervical carcinoma samples and matched control specimens. Polymerase chain reaction was performed using primer specific for two intragenic markers D6S1599 and D6S305 present in Parkin introns 2 and 7, respectively, and one marker (D6S1008) at telomeric end and further electrophoresed on 8% denaturing polyacrylamide gel. Overall, 59 of 105 (56%) samples showed loss of heterozygosity in at least one locus in the region examined. The percentage of loss of heterozygosity for these markers ranged from 25% (D6S1008) to 48% (D6S305). Chi-square test was performed, and loss of heterozygosity was found significantly higher in both the intragenic markers (D6S1599 and D6S305) when compared with the locus at telomeric end (D6S1008) with P<0.05. These data argue that Parkin is a tumor suppressor gene whose inactivation may play an important role in the carcinoma of uterine cervix.

Gene dosage, expression, and ontology analysis identifies driver genes in the carcinogenesis and chemoradioresistance of cervical cancer

Integrative analysis of gene dosage, expression, and ontology (GO) data was performed to discover driver genes in the carcinogenesis and chemoradioresistance of cervical cancers. Gene dosage and expression profiles of 102 locally advanced cervical cancers were generated by microarray techniques. Fifty-two of these patients were also analyzed with the Illumina expression method to confirm the gene expression results. An independent cohort of 41 patients was used for validation of gene expressions associated with clinical outcome. Statistical analysis identified 29 recurrent gains and losses and 3 losses (on 3p, 13q, 21q) associated with poor outcome after chemoradiotherapy. The intratumor heterogeneity, assessed from the gene dosage profiles, was low for these alterations, showing that they had emerged prior to many other alterations and probably were early events in carcinogenesis. Integration of the alterations with gene expression and GO data identified genes that were regulated by the alterations and revealed five biological processes that were significantly overrepresented among the affected genes: apoptosis, metabolism, macromolecule localization, translation, and transcription. Four genes on 3p (RYBP, GBE1) and 13q (FAM48A, MED4) correlated with outcome at both the gene dosage and expression level and were satisfactorily validated in the independent cohort. These integrated analyses yielded 57 candidate drivers of 24 genetic events, including novel loci responsible for chemoradioresistance. Further mapping of the connections among genetic events, drivers, and biological processes suggested that each individual event stimulates specific processes in carcinogenesis through the coordinated control of multiple genes. The present results may provide novel therapeutic opportunities of both early and advanced stage cervical cancers.

Guidelines of the Italian Society for Virology on HPV testing and vaccination for cervical cancer prevention

OBJECTIVE

To provide guidelines for health-care providers on strategies for cervical cancer prevention based on HPV testing and anti-HPV vaccination.

OUTCOMES

Overall efficacy of different preventive strategies, assessing reduction in the incidence of invasive cervical cancer and precancerous lesions.

EVIDENCE

Medline and the Cochrane Database were searched for articles in English on subjects related to HPVs, HPV diagnosis, HPV anogenital lesions, cervical cancer, HPV testing, and HPV vaccines, in order to elaborate an up-dated document. Relevant Italian Government publications and position papers from appropriate health and family planning organizations were also reviewed.

VALUES

The quality of the evidence and ranking of recommendations for practice were rated using criteria defined by SIV, which were adapted from the Canadian Task Force on Preventive Health Care.

OPCML gene promoter methylation and gene expression in tumor and stroma cells of invasive cervical carcinoma

To investigate the CpG island methylation and the mRNA expression of OPCML gene in patients with cervical carcinoma, we collected tumor and stroma cells from 36 invasive cervical carcinoma samples and 16 normal cervical tissues as well as Hela cells. Methylation specific PCR was used to detect promoter CpG island methylation status, and fluorescence quantitative RT-PCR was used to detection of OPCML gene expression. Our data showed that OPCML gene promoter methylation may play an important role in the carcinogenesis of cervical carcinoma and OPCML gene may be a cervical carcinoma-associated candidate TSG (tumor suppressor gene).

Chromosomal gain of 3q and loss of 11q often associated with nodal metastasis in early stage cervical squamous cell carcinoma

BACKGROUND/PURPOSE

Cervical cancer remains a health problem among women worldwide. Delineation of genetic changes is critical to understanding the molecular basis of tumor progression, as well as for identifying genetic markers for early identification of patients at high risk for a poor outcome.

METHODS

To provide comparative genomic hybridization data for cervical squamous cell carcinoma in Taiwan, and to gain further insight into genetic markers associated with lymph node metastasis of this disease, we performed comparative genomic hybridization analysis of 30 consecutive cases of cervical squamous cell carcinoma (24 stage IB and 6 stage IIB).

RESULTS

The results disclosed that higher staged tumors or those with lymph node metastasis had more chromosomal imbalances. The commonly recurrent chromosomal imbalances were gains of 3q (46.7%), 1q (36.7%) and 8q (20.0%) and losses of 11q (36.7%), 3p (33.3%), 6q (23.3%), and 2q (20.0%). The frequencies of these chromosomal imbalances in stage IB and IIB tumors did not differ significantly. However, when compared with tumors without lymph node metastasis, the loss of 11q14-q22 (5/9 vs. 3/21, p = 0.019) and gains of 3q11-q22 and 3q26-qter (6/9 vs. 5/21, p = 0.026) were significantly more prevalent in tumors with lymph node metastasis.

CONCLUSION

The results suggest that certain tumor-associated genes residing on 3q and 11q warrant further investigation to elucidate their role in the progression of this disease.

Sex chromosome alterations associate with tumor progression in sporadic colorectal carcinomas

PURPOSE

The X and Y chromosomes have been associated with malignancy in different types of human tumors. This study attempts to determine the involvement of X chromosome and pseudoautosomal regions (PAR) in sporadic colorectal carcinogenesis.

EXPERIMENTAL DESIGN

An allelotyping of X chromosome in 20 premalignant and 22 malignant sporadic colorectal tumors (CRC) from female patients and an analysis of losses [loss of heterozygosity (LOH)] on PARs from 44 CRCs and 12 adenomas of male patients were carried out. In male tumors, a fluorescence in situ hybridization analysis was done to identify which sex chromosome was possibly lost.

RESULTS

The LOH frequency in female CRCs was 46% with higher incidence in patients with tumor recurrence than in those who were disease-free (P < 0.01) and with a significant difference from adenomas (11%; P < 0.0001). The LOH rate of PARs in male CRCs was 37% with a frequency significantly higher in patients with recurrence (P < 0.03). These results were maintained also when data from PARs of all 66 male and female patients were cumulated (P < 0.05). LOH in PARs was significantly correlated with LOH at 5q (P < 0.01) and 18q (P < 0.01), early and late events, respectively, in colorectal carcinogenesis. Fluorescence in situ hybridization analysis in male patients with extensive PAR LOH revealed a preferential loss of the Y chromosome.

CONCLUSIONS

Our data suggest a role for sex chromosome deletions in the malignant progression of sporadic CRCs and support the presence in the PARs of putative tumor suppressor genes involved in the progression of human sporadic CRCs.

Screening of microsatellite markers in penile cancer reveals differences between metastatic and nonmetastatic carcinomas

Penile cancer, observed only rarely in the western world, represents a carcinoma that may be cured by resection of primary lesion and in case of lymph node metastasis by early lymph node dissection. This early inguinal lymphadenectomy bares a significant better survival even in cases of nonpalpable lymph nodes, but carries also a high risk of overtreatment, especially in lower tumor stages. Due to the low incidence, only few data are available on the molecular genetic background of this tumor, especially concerning tumor progression and metastasis. Therefore, we studied 62 microsatellite markers in 28 penile carcinomas searching for markers predicting progression or outcome. LOH in more than 25% of primary tumors was found on six different chromosomes, including 2q, 6p, 8q, 9p, 12q and 17p13. Statistically significant correlations could be established in D6S260 to clinical outcome and in markers from chromosomes 6, 9 and 12 to tumor stage and metastasis. These regions are worthy for further analysis concerning tumor suppressor genes and metastasis suppressor genes.

Gene dosage alterations revealed by cDNA microarray analysis in cervical cancer: identification of candidate amplified and overexpressed genes

Cervical cancer (CC) cells exhibit complex karyotypic alterations, which is consistent with deregulation of numerous critical genes in its formation and progression. To characterize this karyotypic complexity at the molecular level, we used cDNA array comparative genomic hybridization (aCGH) to analyze 29 CC cases and identified a number of over represented and deleted genes. The aCGH analysis revealed at least 17 recurrent amplicons and six common regions of deletions. These regions contain several known tumor-associated genes, such as those involved in transcription, apoptosis, cytoskeletal remodeling, ion-transport, drug metabolism, and immune response. Using the fluorescence in situ hybridization (FISH) approach we demonstrated the presence of high-level amplifications at the 8q24.3, 11q22.2, and 20q13 regions in CC cell lines. To identify amplification-associated genes that correspond to focal amplicons, we examined one or more genes in each of the 17 amplicons by Affymetrix U133A expression arrays and semiquantitative reverse-transcription PCR (RT-PCR) in 31 CC tumors. This analysis exhibited frequent and robust upregulated expression in CC relative to normal cervix for genes EPHB2 (1p36), CDCA8 (1p34.3), AIM2 (1q22-23), RFC4, MUC4, and HRASLS (3q27-29), SKP2 (5p12-13), CENTD3 (5q31.3), PTK2, RECQL4 (8q24), MMP1 and MMP13 (11q22.2), AKT1 (14q32.3), ABCC3 (17q21-22), SMARCA4 (19p13.3) LIG1 (19q13.3), UBE2C (20q13.1), SMC1L1 (Xp11), KIF4A (Xq12), TMSNB (Xq22), and CSAG2 (Xq28). Thus, the gene dosage and expression profiles generated here have enabled the identification of focal amplicons characteristic for the CC genome and facilitated the validation of relevant genes in these amplicons. These data, thus, form an important step toward the identification of biologically relevant genes in CC pathogenesis. This article contains Supplementary Material available at http://www.interscience.wiley.com/jpages/1045-2257/suppmat.

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.

Combined array-comparative genomic hybridization and single-nucleotide polymorphism-loss of heterozygosity analysis reveals complex genetic alterations in cervical cancer

Background

Cervical carcinoma develops as a result of multiple genetic alterations. Different studies investigated genomic alterations in cervical cancer mainly by means of metaphase comparative genomic hybridization (mCGH) and microsatellite marker analysis for the detection of loss of heterozygosity (LOH). Currently, high throughput methods such as array comparative genomic hybridization (array CGH), single nucleotide polymorphism array (SNP array) and gene expression arrays are available to study genome-wide alterations. Integration of these 3 platforms allows detection of genomic alterations at high resolution and investigation of an association between copy number changes and expression.

Results

Genome-wide copy number and genotype analysis of 10 cervical cancer cell lines by array CGH and SNP array showed highly complex large-scale alterations. A comparison between array CGH and SNP array revealed that the overall concordance in detection of the same areas with copy number alterations (CNA) was above 90%. The use of SNP arrays demonstrated that about 75% of LOH events would not have been found by methods which screen for copy number changes, such as array CGH, since these were LOH events without CNA. Regions frequently targeted by CNA, as determined by array CGH, such as amplification of 5p and 20q, and loss of 8p were confirmed by fluorescent in situ hybridization (FISH). Genome-wide, we did not find a correlation between copy-number and gene expression. At chromosome arm 5p however, 22% of the genes were significantly upregulated in cell lines with amplifications as compared to cell lines without amplifications, as measured by gene expression arrays. For 3 genes, SKP2, ANKH and TRIO, expression differences were confirmed by quantitative real-time PCR (qRT-PCR).

Conclusion

This study showed that copy number data retrieved from either array CGH or SNP array are comparable and that the integration of genome-wide LOH, copy number and gene expression is useful for the identification of gene specific targets that could be relevant for the development and progression in cervical cancer.

The prognostic significance of leukocytosis in cervical cancer

Cervical cancer is a frequent tumor with established prognostic factors such as FIGO stage and hemoglobin levels among others. Despite the fact that paraneoplastic leukocytosis is relatively common in many solid tumors, only isolated cases of cervical cancer patients presenting this abnormality have been published; hence, the clinical significance of leukocytosis is unknown in this tumor type. Retrospective review on the medical records of 294 consecutive newly diagnosed and untreated locally advanced cervical cancer patients who received radiotherapy and concurrent cisplatin was conducted. Leukocytosis was defined as a persistent white blood cell count exceeding 10,800/microL, determined at least twice before commencing chemoradiation providing that patients were free of any active acute or chronic infection or any other condition known to elevate the leukocyte count. The frequency of leukocytosis and their correlation with clinicopathologic features were investigated, as well as their impact on tumor response and survival. Leukocytosis with a median value of 13,300/microL (11,100-28,800) was observed in 35 (11.9%) patients at diagnosis. Leukocytosis was statistically associated only with advanced stages. Clinical complete response was observed in 57% versus 86% of the patients with and without leukocytosis, respectively. In the univariate analysis, leukocytosis, stage, and hemoglobin levels were significant predictors of survival; however, only leukocytosis and the hemoglobin level remained significant predictors of survival in the multivariate analysis. Leukocytosis is common in cervical cancer patients and has a negative prognostic significance.

Dissimilarity in gene expression profiles of lung adenocarcinoma in Japanese men and women

BACKGROUND

Although clinical differences in lung cancer between men and women have been noted, few studies have examined the sex dissimilarity using gene expression analysis.

OBJECTIVE

The purpose of this study was to determine the different molecular carcinogenic mechanisms involved in lung cancers in Japanese men and women.

METHODS

Patients who received surgery for stage I lung adenocarcinoma were included. RNA was extracted from cancerous and normal tissue, and gene expression was then examined with oligonucleotide microarray analysis. A quantitative polymerase chain reaction assay was performed.

RESULTS

In a microarray analysis of tissue from 13 men and 6 women, 12 genes were under-expressed and 24 genes were overexpressed in lung adenocarcinoma in women compared with men. Genes related to cell cycle were present in underexpressed genes, and genes related to apoptosis, ubiquitination, and metabolism were observed in overexpressed genes. Of interest among the selected genes were WAP four-disulfide core domain 2 (WFDC2) and major histocompatibility complex, class II, DM alpha (HLA-DMA); these genes were classified into 2 groups by hierarchical clustering analysis. Expression of WFDC2 in nonsmokers was significantly higher than that in smokers (P=0.023). However, there was no significant difference in HLA-DMA expression between smokers and nonsmokers.

CONCLUSION

Thirty-six genes that characterize lung adenocarcinoma by sex were selected. This information may contribute to the development of novel diagnostic techniques and treatment modalities that consider sex differences in lung adenocarcinoma.

Identification of chromosomal alterations important in the development of cervical intraepithelial neoplasia and invasive carcinoma using alignment of DNA microarray data

OBJECTIVE

To use microarray data to reveal regions of potential chromosomal loss or gain important in cervical intraepithelial neoplasia (CIN) and invasive cervical cancer by identifying mRNA expression biases in contiguous chromosomal regions.

METHODS

Data from three RNA expression microarray experiments were used: one primary experiment using cDNA arrays profiling gene expression in cervical epithelium from viral cytopathic effect to invasive cancer, one experiment using Affymetrix arrays profiling gene expression in invasive cancerous cervical epithelium, and one experiment using Affymetrix arrays profiling gene expression in CIN cervical biopsy specimens. Gene expression was aligned along chromosomes to reveal regions of significant chromosomal imbalance. Regions showing significant gain or loss and verified in more than one experiment are presented here. RT-PCR was performed to validate expression of one gene in a region.

RESULTS

Gain of 3q was detected from the CIN II (P=0.018), CIN III (P=0.005), and invasive cancer (P=0.0002) cDNA arrays, and gain of 12q was detected from the CIN (P=0.05) and invasive cancer (P=0.05) Affymetrix arrays. Loss of 6p was detected from the CIN III (P=0.004) cDNA arrays and invasive cancer (P=0.05) Affymetrix arrays. Loss of 4q was detected from the invasive cancer (P=0.04) cDNA arrays and invasive cancer (P=0.05) Affymetrix arrays. RAN, located in the region of gain on 12q24.3, was overexpressed in CIN and invasive cancer.

CONCLUSIONS

Alignment of microarray expression data by chromosomes can be used to estimate regions of potential chromosomal aberration and identify differentially expressed genes important in the development of CIN and invasive cancer.

Gene expressions and copy numbers associated with metastatic phenotypes of uterine cervical cancer

Background

A better understanding of the development of metastatic disease and the identification of molecular markers for cancer spread would be useful for the design of improved treatment strategies. This study was conducted to identify gene expressions associated with metastatic phenotypes of locally advanced cervical carcinomas and investigate whether gains or losses of these genes could play a role in regulation of the transcripts. Gene expressions and copy number changes were determined in primary tumors from 29 patients with and 19 without diagnosed lymph node metastases by use of cDNA and genomic microarray techniques, respectively.

Results

Thirty-one genes that differed in expression between the node positive and negative tumors were identified. Expressions of eight of these genes (MRPL11, CKS2, PDK2, MRPS23, MSN, TBX3, KLF3, LSM3) correlated with progression free survival in univariate analysis and were therefore more strongly associated with metastatic phenotypes than the others. Immunohistochemistry data of CKS2 and MSN showed similar relationships to survival. The prognostic genes clustered into two groups, suggesting two major metastatic phenotypes. One group was associated with rapid proliferation, oxidative phosphorylation, invasiveness, and tumor size (MRPS23, MRPL11, CKS2, LSM3, TBX3, MSN) and another with hypoxia tolerance, anaerobic metabolism, and high lactate content (PDK2, KLF3). Multivariate analysis identified tumor volume and PDK2 expression as independent prognostic variables. Gene copy number changes of the differentially expressed genes were not frequent, but correlated with the expression level for seven genes, including MRPS23, MSN, and LSM3.

Conclusion

Gene expressions associated with known metastatic phenotypes of cervical cancers were identified. Our findings may indicate molecular mechanisms underlying development of these phenotypes and be useful as markers of cancer spread. Gains or losses of the genes may be involved in development of the metastatic phenotypes in some cases, but other mechanisms for transcriptional regulation are probably important in the majority of tumors.

Expression of platelet derived growth factor family members and the potential role of imatinib mesylate for cervical cancer

Background

Despite significant achievements in the treatment of cervical cancer, it is still a deadly disease; hence newer therapeutical modalities are needed. Preliminary investigations suggest that platelet-derived growth factor (PDGF) might have a role in the development of cervical cancer, therefore it is important to determine whether this growth factor pathway is functional and its targeting with imatinib mesylate leads to growth inhibition of cervical cancer cells.

Results

PDGF receptors (PDGFR) and their ligands are frequently expressed in cervical cancer and the majority exhibited a combination of family members co-expression. A number of intronic and exonic variations but no known mutations in the coding sequence of the PDGFRα gene were found in cancer cell lines and primary tumors. Growth assays demonstrated that PDGFBB induces growth stimulation that can be blocked by imatinib and that this tyrosine kinase inhibitor on its own inhibits cell growth. These effects were associated with the phosphorylation status of the receptor.

Conclusion

The PDGFR system may have a role in the pathogenesis of cervical cancer as their members are frequently expressed in this tumor and cervical cancer lines are growth inhibited by the PDGFR antagonist imatinib.

Molecular biology of squamous cell carcinoma of the anus

BACKGROUND

Squamous cell carcinoma of the anal canal provides a model for studying the contribution of human papillomavirus (HPV) and human immunodeficiency virus (HIV) infection to the development of neoplasia. This paper reviews the existing literature relating to the molecular biology of anal squamous cell carcinoma and proposes a theory of pathogenesis.

METHODS

A Medline literature search was performed to identify English articles on the pathogenesis of squamous cell carcinoma of the anus; further articles were obtained from the references quoted in the literature initially reviewed.

RESULTS

HPV infection and subsequent HPV DNA integration are necessary, but not sufficient, to cause cancer progression. Loss of heterozygosity at 11q23 is the most consistent genomic change observed. Loss of heterozygosity at 17p, 18q and 5q is frequently observed in tumours of HIV-negative patients, but not in those of HIV-positive patients. Current data suggest that mutations in p53, DCC and APC tumour suppressor genes contribute to the stepwise progression of anal squamous cell carcinoma in immunocompetent individuals.

CONCLUSION

In comparison with immunocompetent individuals, HIV-positive patients have persistent HPV infection in the anal canal. In this population, microsatellite instability, rather than chromosomal instability, appears to be a preferred pathway for rapid progression towards invasive carcinoma.

HPV-mediated cervical carcinogenesis: concepts and clinical implications

Persistent infection with a high-risk human papillomavirus (hrHPV) is generally accepted as a necessary cause of cervical cancer. However, cervical cancer is a rare complication of an hrHPV infection since most such infections are transient, not even giving rise to cervical lesions. On average, it takes 12-15 years before a persistent hrHPV infection may ultimately, via consecutive premalignant stages (ie CIN lesions), lead to an overt cervical carcinoma. This argues that HPV-induced cervical carcinogenesis is multi-step in nature. In this review, the data from hrHPV-mediated in vitro transformation studies and those obtained from analysis of clinical specimens have been merged into a cervical cancer progression model. According to this model, a crucial decision maker in the early stages following infection involves individual susceptibility for certain HPV types depending on the genetic make-up of immune surveillance determinants. Once a CIN lesion has developed, altered transcriptional regulation of the viral E6/E7 oncogenes, resulting in genomic instability and distinguishing the process of cell transformation from a productive viral infection, probably provides the subsequent important step towards malignancy. The additional (epi)genetic alterations that subsequently accumulate in high-grade CIN lesions may result in overt malignancy via immortality and growth conditions that gradually become less sensitive to growth-modulating influences mediated by cytokines and cell-cell and cell-matrix adhesions. The potential implications of hrHPV testing and some other biomarkers deduced from this model for cervical screening and the clinical management of CIN disease are also discussed.

Genomic integration of oncogenic HPV and gain of the human telomerase geneTERC at 3q26 are strongly associated events in the progression of uterine cervical dysplasia to invasive cancer

Recently proposed events associated with the progression of cervical intraepithelial neoplasia (CIN) 2/3 to cervical carcinoma include integration of human papillomavirus (HPV) into the host genome, genomic instability, and an increase in chromosome 3q copy number. In particular, the gene coding for the RNA component of telomerase (TERC) at 3q26 has been implicated as a possible candidate gene. Since it is not known to date how these events are temporally related during cervical carcinogenesis, the aim of the present study was to assess the correlation between TERC gene copy number and the physical status of HPV during progression in cervical neoplasia. Solitary precursor lesions of the uterine cervix (CIN 2/3, n = 17), lesions associated with a micro-invasive carcinoma (CIN 3&mCA, n = 13), and advanced invasive carcinomas (invCA, n = 7) were analysed by fluorescence in situ hybridization (FISH) to determine the physical status of the virus and TERC gene copy number. The TERC gene was increasingly gained with progression of CIN 2/3 (3 of 17) through CIN 3&mCA (7 of 13) to invCA (5 of 7). In the lesions exhibiting gain of TERC, the virus was predominantly integrated. This was seen in eight of ten diploid lesions, indicating that these events can occur prior to aneuploidization and are strongly associated with the progression of CIN 3 to mCA and invCA (p < 0.001). With progression to carcinoma, a number of these lesions show polyploidization, resulting in aneuploidy and high TERC gene copy numbers. In conclusion, genomic integration of oncogenic HPV and gain of the human telomerase gene TERC appear to be important associated genetic events in the progression of uterine cervical dysplasia to invasive cancer.

Xq25 and Xq26 identify the common minimal deletion region in malignant gastroenteropancreatic endocrine carcinomas

Loss of heterozygosity (LOH) for markers on X chromosome are associated with malignancy in endocrine tumors of the stomach and pancreas. The aim of this work is to investigate low-grade, well-differentiated endocrine carcinomas (WDEC) vs high-grade, poorly differentiated endocrine carcinomas (PDEC) of the gastroenteropancreatic (GEP) tract for common deletion regions on X chromosome. We performed a comparative allelotyping analysis with 24 highly polymorphic markers for the X chromosome in 12 WDECs and 5 PDECs. Overall, the LOH frequency in all informative loci investigated was 59% in primary and 61% in metastasis, with a significantly higher rate in PDECs than in WDECs (p<0.015 for primary and p<0.00005 for metastasis). In both WDECs and PDECs, the small Xq25 region as defined by DXS8059, DXS8098, and DXS8009 markers showed higher LOH rate as compared to the rest of the chromosome markers (p<0.04). In addition, LOH was very frequently elevated also in DXS294 and in DXS102 loci mapping the chromosomal region Xq26. In no instances differences were found between primary tumors and metastases. Methylation analysis revealed that Xq25 loss preferentially occurred on the inactive X chromosome, a feature in agreement with findings from other human cancers suggesting escape of tumor suppressor genes to X chromosome inactivation at this region. Overall, our data indicate that the two chromosomal regions, Xq25 and Xq26, may participate to the malignant progression of GEP endocrine carcinomas.

HPV-mediated transformation of the anogenital tract

Infection with high-risk human papillomavirus (HR-HPV) has been associated with intraepithelial neoplasia and carcinomas at various sites of the anogenital tract, including the cervix, vulva, vagina, penis and anus. Although HR-HPV is a necessary cause for cervical cancer, the majority of anal cancers and a subset of cancers at other genital sites, additional (epi)genetic events are required for malignant transformation. HPV-mediated transformation of human epithelial cells has been recognized as a multi-step process resulting from deregulated transcription of the viral oncogenes E6 and E7 in the proliferating cells. Interference of E6 and E7 with cell cycle regulators induces genetic instability, which drives the continuous selection of oncogenic alterations providing cells with a malignant phenotype. Early genetic events during cervical carcinogenesis associated with immortalization, include deletions at chromosomes 3p, 6 and 10p, whereas amongst others gain of chromosome 3q, loss of chromosome 11 and epigenetic alterations such as inactivation of the TSLC1 tumor suppressor gene represent later events associated with tumor invasion.

Tetraploidy and chromosomal instability are early events during cervical carcinogenesis

Chromosomal instability as manifested by increases in aneuploidy and structural chromosome aberrations is believed to play a critical role in the intermediate to late stages in the development of cervical malignancies. The current study was designed to determine the role of tetraploidy in the formation of aneuploidy and ascertain the occurrence of these alterations during the earlier stages of cervical carcinogenesis. Cervical cell samples, with diagnoses ranging from Normal to high-grade lesions, (HSIL) were obtained from 143 women and were evaluated for chromosomal alterations using dual-probe fluorescence in situ hybridization. Cervical cells from a subset of the group were also evaluated for chromosomal instability in the form of micronuclei. The frequencies of cells exhibiting either tetrasomy or aneusomy for Chromosomes 3 and 17 increased significantly with disease progression and displayed distinctive patterns where aneusomy was rarely present in the absence of tetrasomy. The frequencies of micronuclei that formed through either chromosomal loss or breakage increased significantly in both the low-grade and high-grade diagnostic categories and were highly correlated with both the number of tetrasomic and aneusomic cervical cells. In addition, a unique chromosomal alteration involving a significant non-random loss of Chromosome 17 specific to near-tetraploid aneusomic cells (trisomy 17 and tetrasomy 3) was observed. We conclude that tetraploidy and chromosomal instability are related events occurring during the early stages of cervical carcinogenesis that predispose cervical cells to the formation of aneuploidy frequently involving the loss of Chromosome 17.

Expression of epidermal growth factor receptor in cervical tissue and serum in patients with cervical neoplasia

OBJECTIVE

We hypothesized that there may be a relationship between epidermal growth factor receptor (EGFR) expression in cervical tissue and serum in patients with cervical neoplasia.

MATERIALS AND METHODS

The expression of EGFR was measured in cervical tissues from 23 cervical intraepithelial neoplasia patients and 16 cervical carcinoma patients using immunohistochemical staining and the level of serum EGFR extracellular domain was measured in serum from 17 cervical intraepithelial neoplasia patients and 14 cervical carcinoma patients using enzyme-linked immunosorbent assay.

RESULTS

The expression of EGFR was significantly increased as normal cervical tissue progressed to cervical intra-epithelial neoplasia then to cervical carcinoma (p = .009). The mean level of serum EGFR according to the intensity of immunohistochemical staining in negative, weakly positive, positive, and strongly positive staining was 19.36 +/- 3.12 fmol/mL, 20.99 +/- 3.59 fmol/mL, 29.08 +/- 16.86 fmol/mL, and 24.34 +/- 10.35 fmol/mL, respectively (p = .450).

CONCLUSIONS

We believe that the level of serum EGFR may have a similar role as tumor markers such as the EGFR expression in cervical neoplastic tissue.

Genomic stability and tumorigenesis

Cancer research needs to explain the observed incidence of cancer. Many factors determine this process, including: the number of susceptible cells in the tissue of origin; the number of normal cell divisions through which susceptible cells pass in normal development and turnover; the number of cell divisions during tumorigenesis; the selective advantage which tumour cells have acquired; the ease of detection of a cancer; the number of mutations which are required for malignancy; the possible stepwise nature of tumorigenesis; the value of the normal mutation rate; the presence of extrinsic factors such as mutagens or growth promoters; the presence and strength of genomic instability, a phenomenon which has received a great deal of attention. We know very little about most of the factors and their influence in humans. We cannot, therefore, readily answer the question as to whether or not the observed incidence of cancer is what we would expect. Specifically, it is not yet possible to assess whether or not genomic instability is a prerequisite for carcinogenesis. Mathematical models, which assess the importance of genomic instability in tumorigenesis can be helpful, but require interpretation in the context of our overall ignorance. Experimental data have shown genomic instability in some cancers, but we do not yet know whether or not hypermutation initiates and drives tumorigenesis.

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.

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.

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.

Loss of heterozygosity on chromosome 6 in HPV-16 positive cervical carcinomas carrying the DRB1*1501-DQB1*0602 haplotype

High-risk human papillomaviruses (HPVs), specifically HPV-16 and -18, have been associated with the development of carcinoma in situ (CIS) and of invasive cervical cancer (CC). However, only a small fraction of HPV-infected women will show signs of disease progression, suggesting that other factors in the carcinogenic pathway are needed. We previously demonstrated that human leukocyte antigen (HLA) DRB1*1501-DQB1*0602 (high risk) was associated with the development of CIS and CC tumors in HPV-16-positive patients. To characterize the molecular changes that could be relevant to tumor progression, we compared the extent of loss of heterozygosity (LOH) on chromosome 6 in HPV-16-positive CIS patients who were carriers of high-risk and neutral HLA haplotypes. CIS and CC cases demonstrated similar LOH patterns. A wide range of LOH frequencies was found at 6p (10-53%) and 6q (5-28%) in CIS cases, suggesting that LOH is an early event in the carcinogenic process. A comparative analysis of LOH frequencies in the high-risk versus the neutral HLA haplotypes showed a statistically significant difference in the extent of LOH at 6p24-p25 (58.6% versus 25.8%; P = 0.018) and at 6p21.3 (79.3% versus 35.5%; P = 0.001), a region that contains the HLA complex. LOH at this region could affect genes encoding HLA class I-II molecules, as well as factors responsible for the assembly, transport, and stable expression of HLA molecules. These losses may be a reflection of both an abnormal immune response and a general genome-wide instability resulting from virus persistence.

Telomerase activity in high-grade cervical lesions is associated with allelic imbalance at 6Q14-22

Our study attempts to establish the relationship between telomerase activity and allelic imbalance (AI) on chromosomes 3p and 6 in high-risk HPV-containing cervical lesions. These chromosomes were implicated previously in telomerase regulation in HPV containing immortalized cells and cervical cancer cells. Allelotyping and telomerase analysis were carried out on 28 high-grade cervical lesions (CIN III: n = 20; cervical carcinomas: n = 8), using 23 microsatellite markers on 3p, 6p and 6q. Clear telomerase activity was found in 17 of 28 lesions (61%). Allelic imbalance frequency at 6q14-22 was significantly higher in lesions with detectable telomerase activity, compared to lesions without telomerase activity (p = 0.02). No association was found between telomerase activity and AI at any of the remaining regions studied on 3p and chromosome 6. In addition, in telomerase positive passages of the HPV 16 immortalized cell line FK16A, shown recently to be responsive to chromosome 6 mediated telomerase repression, AI was found in the overlapping region of 6q14-27. These data suggest that 6q14-22 may contain 1 or more genes involved in telomerase deregulation and immortalization during cervical carcinogenesis.

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.

Polymorphism at the -308-promoter position of the tumor necrosis factor-alpha (TNF-alpha) gene and cervical cancer

The purpose of the study was to investigate the hypothesis that the genetically programmed ability to produce low, medium, or high levels of tumor necrosis factor-alpha (TNF-alpha), as determined by TNF-alpha promoter polymorphism at position 308, influenced the development of cancer of the uterine cervix. The population was recruited from patients attending gynecological clinics at two teaching hospitals in Harare, Zimbabwe. Laboratory tests were performed in the Departments of Immunology and Medical Microbiology, Medical School, University of Zimbabwe. One hundred and three patients with invasive cancer of the uterine cervix and 101 healthy women were included in the study. All patients and healthy controls were from the Shona ethnic groups that inhabit northern Zimbabwe. DNA was purified from cervical cytobrush samples obtained from women with cervical cancer. In random cases a second DNA sample was extracted from patient blood. Control DNA was extracted from urine or peripheral blood samples from the healthy women. Detection of allele A and /or G at the 308 position in the promoter region of the TNF-alpha gene was carried out using the amplification refractory mutation system-polymerase chain reaction (ARMS-PCR) technique. Polymorphism in the amplified products was detected by gel electrophoresis. There was no statistically significant difference in the distribution of the low (G) or high (A) producer alleles at position 308 of the TNF-alpha gene between patients with cervical cancer and healthy women. The high producer haplotype AA was identified in only one patient with cervical cancer and two healthy women. These data suggest that the genetically acquired ability to produce higher levels of TNF-alpha is present in a minority of women with or without cervical cancer in the Zimbabwean population. Homozygosity for allele 308A is very rare. High-producer allele 308A as well as high-producer haplotypes AA is significantly less common in a Zimbabwean population than in a European population.

Genetic alterations in cervical carcinomas: frequent low-level amplifications of oncogenes are associated with human papillomavirus infection

The development of cervical carcinoma is closely associated with HPV infection. However, other genetic alterations also play an important role. In this study, we analyzed copy number alterations of several oncogene loci in a panel of 84 cervical tumors. Sixty-five (77%) tumors were HPV DNA-positive, and most were infected with type 16 or type 18 or both. The oncogenes studied include PIK3CA at 3q26.3, TERT at 5p15.33, C-MYC at 8q24, CCND1 at 11q13.3, ERBB2 at 17q21.2 and locus region 20q13.2. Amplification of 1 or more genes was detected in 55 (65%) cases using interphase FISH. PIK3CA was amplified in 43% of tumors, followed by TERT (33%), 20q13.2 (30%), ERBB2 (29%), C-MYC (25%) and CCND1 (12%). Most tumors showed low-level amplification with 3-7 copies of these genes, and complex changes involving 3 or more genes occur more frequently in tumors at advanced stages. Increased protein expression of c-erbB2 and c-myc was observed in tumors with the corresponding gene amplification. Oncogene alterations were found more often in HPV-infected cases, particularly for C-MYC and TERT. These findings indicate that HPV-associated cervical carcinomas bear frequent alterations of these genes, which may have critical biologic impact on the development and progression of carcinoma of the uterine cervix.

Polymorphism in codons 10 and 25 of the transforming growth factor-beta 1 (TGF-beta1) gene in patients with invasive squamous cell carcinoma of the uterine cervix

Transforming growth factor-beta 1 (TGF-beta1) has a multifactorial role in the development of cervical cancer. It potently inhibits the growth of epithelial cells that harbour oncogenic human papilloma viruses (HPVs). TGF-beta1 also inhibits the expression of the early viral transforming regions E6 and E7, which appear to be the key oncoproteins. It has been suggested that squamous cell carcinomas are devoid of TGF-beta1, raising the possibility that elevated levels of this growth factor could protect against cervical cancer. It is also recognized that the production and levels of TGF-beta1 are genetically predetermined and individually variable. Two genetic polymorphisms in the DNA encoding the leader sequence of the TGF-beta1 gene have been described and shown to be associated with the production of high or low TGF-beta1 levels in vivo and in vitro. We hypothesized that the inheritance of these polymorphisms could influence the development of invasive cervical cancer. This hypothesis was investigated by studying polymorphism in codons 10 and 25 of the TGF-beta1 gene. We studied 97 patients with invasive cervical cancer and 73 healthy controls and found that the distributions of alleles T (Leu) and/or C (Pro) and alleles G (Arg) and/or C (Pro) in codons 10 and 25, respectively, were similar. There was no significant association between the alleles and the histological degree of cancer differentiation. It appears that the role of this growth factor in cervical oncogenesis is not related to the point mutations that we examined in codons 10 and 25 of the TGF-beta1 gene. We speculate that other factors, including additional polymorphisms of the TGF-beta1 gene, the status of TGF-beta1 receptors, the complex cytokine network, differential responsiveness of cells to the stimuli, and the status of the precancer/cancer genome, may play a role in development of invasive cervical cancer.

Hemizygous deletions in the HLA region account for loss of heterozygosity in the majority of diffuse large B-cell lymphomas of the testis and the central nervous system

Loss of heterozygosity (LOH) is a major mechanism for inactivation of tumor-suppressor genes and has been observed in various solid tumors and lymphomas. The human leukocyte antigen (HLA) region is located at chromosome band 6p21.3, and loss or alteration of this region may provide tumor cells with a mechanism to escape from the immune system. We previously identified small homozygous deletions within the HLA class II region in many of the diffuse large B-cell lymphomas (DLCLs) of the central nervous system (CNS) and the testis. In the present study, we focused on the mechanism leading to LOH in the HLA region. Twenty microsatellite markers, of which 12 were specific for HLA, were applied on 11 extranodal DLCLs of the CNS and 28 of the testis. Additionally, fluorescence in situ hybridization with seven HLA-specific probes and a centromere 6-specific probe was performed on 20 cases to study the mechanism of LOH. In contrast to previously published data on spontaneously mutated lymphoblastoid cell lines, intrachromosomal hemizygous deletion, not mitotic recombination, was the major cause of LOH of the HLA region in these lymphomas. However, opposed to data in colorectal cancer, these deletions were rarely (one of nine cases) associated with an interchromosomal rearrangement such as a translocation.

Genome-wide screening of laser capture microdissected gastric signet-ring cell carcinomas

Gastric signet-ring cell carcinoma comprises a distinct category of gastric cancers and has been reported to have poor prognosis. In an attempt to define genetic changes involved in the pathogenesis of this lesion in an in vivo state, we isolated signet-ring cell carcinoma cells from freshly fixed smears of tumor tissues of 7 primary gastric signet-ring cell carcinomas by laser capture microdissection and applied comparative genomic hybridization (CGH) to screen for DNA sequence copy number changes. Frequent chromosomal gains were detected on 2q, 5p, 7q, 14q and 20q, each in 6/7 cases, on 9q, 12q, 17q, and 19q, each in 5/7 cases, and on 18p in 4/7 cases. Frequent losses were observed on 6p and 17p, each in 5/7 cases, on 6q, and 21p, each in 4/7 cases, and on 3p, 8p and 8q, each in 3/7 cases. Losses on 6p have rarely been observed in conventional types of gastric carcinomas reported in the literature. These data provide the first evidence for the occurrence of specific genomic aberrations in gastric signet-ring cell carcinomas. Our observation of frequent losses on 6p chromosomal arm may provide novel abnormalities of potential significance in gastric signet-ring cell carcinomas, suggesting the involvement of genes residing in this region in the genesis of the disease.

Malignancy-associated allelic losses on the X-chromosome in foregut but not in midgut endocrine tumours

Information on genetic changes involved in the progression of gastroenteropancreatic (GEP) endocrine tumours is scanty. On the other hand, the identification of molecular markers of malignancy could be crucial for the prognostic evaluation of these neoplasms, which is hardly predictable on the basis of conventional histological criteria. An association of X-chromosome deletions with malignancy has already been found in gastric endocrine tumours. To investigate this further, a comparative loss of heterozygosity (LOH) analysis was performed on 17 pancreatic endocrine tumours (PETs) and 17 intestinal (ten ileal, six appendiceal, and one rectal) carcinoids from female patients. The relationship of X-chromosome LOH with the ploidy status of the neoplasms was also investigated. LOH was found in six of eight malignant PETs (60% of the informative markers), but was infrequent in the nine benign ones (4.5%). In contrast, although retention of heterozygosity was consistently observed in benign midgut tumours, LOH was infrequent in malignant carcinoids (15%). No correlation was found between LOH and the ploidy status. These results indicate an association between X-chromosome LOH and malignancy in foregut endocrine tumours. The lack of such an association in midgut carcinoids suggests that different molecular mechanisms are involved in the progression of these two categories of endocrine neoplasms, which are otherwise considered to be closely related. These findings emphasize the need for further molecular studies on GEP endocrine tumours, carefully subdivided according to their anatomical site of origin.

Comparative genomic hybridization detects genetic alterations during early stages of cervical cancer progression

Invasive cervical carcinoma is thought to arise from cervical intraepithelial neoplasm (CIN). Genetic changes that occur during progression of CIN to cervical carcinoma are poorly understood, although they appear to be directly involved in this process. We used comparative genomic hybridization (CGH) with precise microdissection and degenerate oligonucleotide primed-polymerase chain reaction (DOP-PCR) to detect genetic alterations in normal epithelial, CIN, and invasive carcinoma tissues colocalized in tumors from 18 patients with squamous cell carcinoma of the uterine cervix. Gains on chromosome 1 and on 3q and losses on 2q, 3p, 4, 6p, 11q, and 17p were frequent alterations found in CIN and invasive carcinoma lesions. Interestingly, several of these genetic changes were observed in preinvasive carcinoma lesions. The frequency and average number of genetic alterations corresponded directly to the extent to which the cervical carcinoma had progressed. Frequent alterations were found in more than 90% of CIN III lesions. Gains on 3q and losses on 11q were the most prevalent genetic alterations found in association with uterine cervix carcinogenesis. The common regions of alteration were 3q26.1-q28 and 11q23-qter. The majority of tumor samples showed variability in genetic alterations across lesion types within a single specimen.

Loss of sequences on the short arm of chromosome 17 is a late event in squamous carcinoma of the cervix

AIMS

To determine by fluorescence in situ hybridisation (FISH) whether deletion of D17S34, a subtelomeric probe for 17p, occurs in invasive squamous carcinoma of the cervix, and to determine the extent of such loss by analysis of the p53 and HER2/NEU genes.

METHODS

Fourteen invasive squamous cell carcinomas of the cervix were investigated by FISH for D17S34, p53, and HER2/NEU. Dual hybridisation of each probe with the chromosome 17 alpha satellite (D17Z1) probe was performed on paraffin wax embedded sections, and the fluorescence ratios of the paired signals were determined. Broad spectrum human papillomavirus (HPV) typing by ISH and GP5+/6+ polymerase chain reaction was also performed.

RESULTS

Twelve tumours were HPV positive, nine with HPV-16, and one each with types 18, 31, and 39. Loss of D17S34 was identified in four tumours, one of which was HPV negative. In one tumour, D17S34 loss was accompanied by loss of p53 only, suggesting that deletion was limited to the p arm. A second tumour showed simultaneous losses of all probes, indicative of whole chromosome 17 loss during tumour growth. The two remaining specimens showed loss of D17S34 only, diffuse in one, and localised within the tumour in the other. Aberrations of p53 or HER2/NEU were not seen independently of D17S34 loss, and loss did not correlate with HPV presence or type.

CONCLUSIONS

These data show that D17S34 loss is prevalent, marking 28% of the invasive squamous carcinomas in this study. The observed intratumoral heterogeneity indicates that, at least in some cases, this loss occurs after invasion and is therefore a late event in the path of cervical carcinogenesis.

Telomerase suppression by chromosome 6 in a human papillomavirus type 16-immortalized keratinocyte cell line and in a cervical cancer cell line

BACKGROUND

High-risk human papillomavirus (HPV) types play a major role in the development of cervical cancer in vivo and can induce immortalization of primary human keratinocytes in vitro. Activation of the telomere-lengthening enzyme telomerase constitutes a key event in both processes. Because losses of alleles from chromosome 6 and increased telomerase activity have been observed in high-grade premalignant cervical lesions, we analyzed whether human chromosome 6 harbors a putative telomerase repressor locus that may be involved in HPV-mediated immortalization.

METHODS

Microcell-mediated chromosome transfer was used to introduce chromosomes 6 and 11 to the in vitro generated HPV type 16 (HPV16)-immortalized keratinocyte cell line FK16A and to the in vivo derived HPV16-containing cervical cancer cell line SIHA: Hybrid clones were analyzed for growth characteristics, telomerase activity, human telomerase reverse transcriptase (hTERT) and HPV16 E6 expression, and telomere length. FK16A hybrid clones were also transduced with an hTERT-containing retrovirus to examine the effect of ectopic hTERT expression on growth. Statistical tests were two-sided.

RESULTS

Introduction of human chromosome 6 but not of chromosome 11 to both cell lines yielded hybrid cells that demonstrated crisis-like features (i.e., enlarged and flattened morphology, vacuolation, and multinucleation) and underwent growth arrest after a marked lag period. In the chromosome 6 hybrid clones analyzed, telomerase activity and hTERT messenger RNA (mRNA) expression were statistically significantly reduced compared with those in the chromosome 11 hybrid clones (for telomerase activity, P =.004 for the FK16A hybrids and P =.039 for the SiHa hybrids; for hTERT mRNA expression, P =.003 for the FK16A hybrids). The observed growth arrest was associated with telomeric shortening. Ectopic expression of hTERT in FK16A cells could prevent the telomeric shortening-based growth arrest induced by chromosome 6.

CONCLUSIONS

Chromosome 6 may harbor a repressor of hTERT transcription, the loss of which may be involved in HPV-mediated immortalization.

Allelic deletion mapping on chromosome 6q and X chromosome inactivation clonality patterns in cervical intraepithelial neoplasia and invasive carcinoma

OBJECTIVE

Loss of heterozygosity (LOH) profiles and X chromosome inactivation patterns are analyzed in 42 patients with cervical intraepithelial neoplasias (CIN), including low-grade (CIN1) and high-grade (CIN2, CIN3) lesions, and 22 patients with invasive cervical carcinomas.

METHOD

Laser capture microdissection was utilized to procure pure matched normal and lesional cells from each case. Sixteen microsatellite markers on four chromosomal arms, 6q21-q25.1, 8p21, 13q12.3--q13, and 17q12--q21, were amplified for LOH, as well as the HUMARA locus for X chromosome inactivation analysis. Eight additional markers spanning the long arm of chromosome 6 were utilized in all cases showing LOH on this arm and in which further tissue material was available for microdissection.

RESULTS

Fifty-five percent of carcinomas showed deletions on chromosome bands 6q21--q25.1, 43% on 13q12.3--q13, and 40% on 17q12--q21. Deletions on 6q were identified in CIN3 (40%), CIN2 (37%), and CIN1 (10%), on 13q in CIN3 (33%) and CIN2 (33%), and rarely on chromosomal arm 17q. Finer 6q mapping revealed that marker D6S310 (q22) represented the centromeric and marker D6S255 (q25--q16) the telomeric boundary of deletion. A second, telomeric area of deletion at marker D6S281 (q27) was also identified. Monoclonal X chromosome inactivation patterns were identified in 12/13 cancers, 13/14 CIN3, 5/10 CIN2, and 0/6 CIN1.

CONCLUSIONS

Two areas of deletion on chromosome 6q were identified in cervical tumors, suggesting the presence of tumor suppressor gene(s) inactivated in this neoplasia. LOH on this arm were identified early during cervical tumor progression. LOH on 13q and 17q also occur in cervical cancers. X chromosome inactivation patterns suggest that CIN develops into a monoclonal lesion during progression from CIN1 to CIN3.