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

Role of chromosomal cohesion and separation in aneuploidy and tumorigenesis

Cell division is a crucial process, and one of its essential steps involves copying the genetic material, which is organized into structures called chromosomes. Before a cell can divide into two, it needs to ensure that each newly copied chromosome is paired tightly with its identical twin. This pairing is maintained by a protein complex known as cohesin, which is conserved in various organisms, from single-celled ones to humans. Cohesin essentially encircles the DNA, creating a ring-like structure to handcuff, to keep the newly synthesized sister chromosomes together in pairs. Therefore, chromosomal cohesion and separation are fundamental processes governing the attachment and segregation of sister chromatids during cell division. Metaphase-to-anaphase transition requires dissolution of cohesins by the enzyme Separase. The tight regulation of these processes is vital for safeguarding genomic stability. Dysregulation in chromosomal cohesion and separation resulting in aneuploidy, a condition characterized by an abnormal chromosome count in a cell, is strongly associated with cancer. Aneuploidy is a recurring hallmark in many cancer types, and abnormalities in chromosomal cohesion and separation have been identified as significant contributors to various cancers, such as acute myeloid leukemia, myelodysplastic syndrome, colorectal, bladder, and other solid cancers. Mutations within the cohesin complex have been associated with these cancers, as they interfere with chromosomal segregation, genome organization, and gene expression, promoting aneuploidy and contributing to the initiation of malignancy. In summary, chromosomal cohesion and separation processes play a pivotal role in preserving genomic stability, and aberrations in these mechanisms can lead to aneuploidy and cancer. Gaining a deeper understanding of the molecular intricacies of chromosomal cohesion and separation offers promising prospects for the development of innovative therapeutic approaches in the battle against cancer.

Aneuploidy as a promoter and suppressor of malignant growth

Aneuploidy has been recognized as a hallmark of tumorigenesis for more than 100 years, but the connection between chromosomal errors and malignant growth has remained obscure. New evidence emerging from both basic and clinical research has illuminated a complicated relationship: despite its frequency in human tumours, aneuploidy is not a universal driver of cancer development and instead can exert substantial tumour-suppressive effects. The specific consequences of aneuploidy are highly context dependent and are influenced by a cell's genetic and environmental milieu. In this Review, we discuss the diverse facets of cancer biology that are shaped by aneuploidy, including metastasis, drug resistance and immune recognition, and we highlight aneuploidy's distinct roles as both a tumour promoter and an anticancer vulnerability.

An Optimization-Driven Analysis Pipeline to Uncover Biomarkers and Signaling Paths: Cervix Cancer

Establishing how a series of potentially important genes might relate to each other is relevant to understand the origin and evolution of illnesses, such as cancer. High-throughput biological experiments have played a critical role in providing information in this regard. A special challenge, however, is that of trying to conciliate information from separate microarray experiments to build a potential genetic signaling path. This work proposes a two-step analysis pipeline, based on optimization, to approach meta-analysis aiming to build a proxy for a genetic signaling path.

Intelligent screening systems for cervical cancer

Advent of medical image digitalization leads to image processing and computer-aided diagnosis systems in numerous clinical applications. These technologies could be used to automatically diagnose patient or serve as second opinion to pathologists. This paper briefly reviews cervical screening techniques, advantages, and disadvantages. The digital data of the screening techniques are used as data for the computer screening system as replaced in the expert analysis. Four stages of the computer system are enhancement, features extraction, feature selection, and classification reviewed in detail. The computer system based on cytology data and electromagnetic spectra data achieved better accuracy than other data.

Automated analysis of fluorescent in situ hybridization (FISH) labeled genetic biomarkers in assisting cervical cancer diagnosis

The numerical and/or structural deviation of some chromosomes (i.e., monosomy and _polysomy of chromosomes 3 and X) are routinely used as positive genetic biomarkers to diagnose cervical cancer and predict the disease progression. Among the available diagnostic methods to analyze the aneusomy of chromosomes 3 and X, fluorescence in situ hybridization (FISH) technology has demonstrated significant advantages in assisting clinicians to more accurately detect and diagnose cervical carcinoma at an early stage, in particular for the women at a high risk for progression of low-grade and high-grade squamous intra-epithelium lesions (LSIL and HSIL). In order to increase the diagnostic accuracy, consistency, and efficiency from that of manual FISH analysis, this study aims to develop and test an automated FISH analysis method that includes a two-stage scheme. In the first stage, an interactive multiple-threshold algorithm is utilized to segment potential interphase nuclei candidates distributed in different intensity levels and a rule-based classifier is implemented to identify analyzable interphase cells. In the second stage, FISH labeled biomarker spots of chromosomes 3 and X are segmented by a top-hat transform. The independent FISH spots are then detected by a knowledge-based classifier, which enables recognition of the splitting and stringy FISH signals. Finally, the ratio of abnormal interphase cells with numerical changes of chromosomes 3 and X is calculated to detect positive cases. The experimental results of four test cases showed high agreement of FISH analysis results between the automated scheme and the cytogeneticist's analysis including 92.7% to 98.7% agreement in cell segmentation and 4.4% to 11.0% difference in cell classification. This preliminary study demonstrates the feasibility of potentially applying the automatic FISH analysis method to expedite the screening and detecting cervical cancer at an early stage.

Amplification of the human telomerase gene in liquid-based preparations is associated with cervical dysplasia and carcinoma

The aim of this study was to analyze the amplification of the human telomerase gene (TERC) in cervical specimens by fluorescence in situ hybridization (FISH), and FISH findings were compared with cytologic and histologic diagnoses. Slides prepared from 123 liquid-based preparations from cervical specimens with cytologic diagnoses of negative for squamous intraepithelial lesion or malignancy (n=20), atypical squamous cells of undetermined significance (n=22), low-grade squamous intraepithelial lesion (n=55), high-grade squamous intraepithelial lesion (n=21), or invasive cervical carcinomas (n=5) were analyzed for the amplification of TERC using a 2-color FISH probe. The results of the cytologic analysis and those of concurrent or subsequent biopsies were compared with the FISH findings. Results showed that amplification of TERC was significantly associated with both cytologic and histologic diagnoses (P<0.05). Patients with high-grade squamous intraepithelial lesion or squamous cell carcinoma cytology diagnoses had significantly higher percentages of cells with the amplification of TERC than did patients with low-grade squamous intraepithelial lesion, ASC-US, and negative for squamous intraepithelial lesion or malignancy (P<0.005). FISH can be performed on cervical liquid-based preparations to detect the amplification of TERC. This test may be an adjunct to cytology screening, early detection of cervix neoplasm, and may determine the progressive potential of individual lesions, especially in high-risk patients.

Dysplastic cells in cytological cervical samples show a high incidence of chromosomal abnormalities

Chromosomal abnormalities are frequent in most cervical cancers. Amplifications of both the 3q26 (TERC) and 8q24 (MYC) loci have been shown to be prevalent in both high-grade lesions and invasive cervical carcinoma. Most of these studies have looked at either the histological sample or at the entire cytological population of cells. We have developed a Papanicolaou (Pap) destaining method that allows for the accurate analysis of individual cells that were previously identified by cytopathology as dysplastic. The application of fluorescence in situ hybridization (FISH) was then implemented to determine the chromosomal status of the dysplastic cells in the samples and correlate the two events. Chromosomal abnormality is over a thousand times more frequent in dysplastic cells compared with their morphologically normal counterparts.

Cervical intraepithelial neoplasia and aneusomy of TERC: assessment of liquid-based cytological preparations

The implementation of effective screening programs has decreased the incidence and mortality of cervical carcinoma. However, single screening tests are subjective and carry a significant false-negative rate. Therefore, supplementary tests to support the Papanicolaou (PAP) smear are being developed. Human papillomavirus (HPV) testing has increased the specificity of the PAP smear, but has high sensitivity rate. This has proven unhelpful in low-grade lesions and in young women. Cervical carcinogenesis is a multifactorial disorder. In addition to exposure to oncogenic HPV, which is regarded as the initiator, there must be a promoter to eventuate in invasive disease. The promoter factor appears to be the acquisition of extra copies of chromosome 3q and has been shown to be a constant recurrence in cervical carcinoma (squamous and adenocarcinomas). The 3q region contains the RNA sequence of the human telomerase gene TERC. Recent studies have shown a strong correlation between high-grade cervical lesions and abnormalities of TERC. This study supports the previous studies and examines the status of the TERC gene in low and high-grade cervical intraepithelial lesions, diagnosed on cytology. ASC-H smears are also examined in an attempt to categorize lesions that are more likely to progress. Potentially this may help identify women in need of close clinical follow-up and early treatment.

Automated detection and analysis of fluorescent in situ hybridization spots depicted in digital microscopic images of Pap-smear specimens

Fluorescence in situ hybridization (FISH) technology has been widely recognized as a promising molecular and biomedical optical imaging tool to screen and diagnose cervical cancer. However, manual FISH analysis is time-consuming and may introduce large inter-reader variability. In this study, a computerized scheme is developed and tested. It automatically detects and analyzes FISH spots depicted on microscopic fluorescence images. The scheme includes two stages: (1) a feature-based classification rule to detect useful interphase cells, and (2) a knowledge-based expert classifier to identify splitting FISH spots and improve the accuracy of counting independent FISH spots. The scheme then classifies detected analyzable cells as normal or abnormal. In this study, 150 FISH images were acquired from Pap-smear specimens and examined by both an experienced cytogeneticist and the scheme. The results showed that (1) the agreement between the cytogeneticist and the scheme was 96.9% in classifying between analyzable and unanalyzable cells (Kappa=0.917), and (2) agreements in detecting normal and abnormal cells based on FISH spots were 90.5% and 95.8% with Kappa=0.867. This study demonstrated the feasibility of automated FISH analysis, which may potentially improve detection efficiency and produce more accurate and consistent results than manual FISH analysis.

Gain of the 3q26 region in cervicovaginal liquid-based pap preparations is associated with squamous intraepithelial lesions and squamous cell carcinoma

BACKGROUND

Chromosomal aberrations have been documented in cervical carcinomas, especially chromosome 3q. The human telomerase RNA gene (hTERC) is located in the chromosome 3q26 region, and its product, telomerase, is involved in the maintenance of chromosome length and stability. Upregulation of telomerase is in general associated with tumorigenesis. In this study, cervicovaginal specimens were analyzed by fluorescence in situ hybridization (FISH) for gain of chromosome 3q26 containing hTERC, and FISH findings were compared with the cytologic and histologic diagnoses.

METHODS

Slides prepared from 66 liquid-based preparations from cervical specimens with cytologic diagnoses of negative for squamous intraepithelial lesion or malignancy (NILM, n=4), atypical squamous cells of undetermined significance (ASC-US, n=15), low-grade squamous intraepithelial lesion (LSIL, n=20), high-grade squamous intraepithelial lesion (HSIL, n=24), or cervical squamous cell carcinoma (SCCA, n=3) were analyzed for aberrations of 3q26 using a commercially available two-color FISH probe. The results of the cytologic analysis and those of concurrent or subsequent biopsies, when available, were compared with the FISH-detected 3q26 abnormalities. The Wilcoxon rank-sum test was used to assess associations between 3q26 gains and diagnoses.

RESULTS

Gain of 3q26 was significantly associated with the cytologic diagnosis (p<0.0001). Patients with HSIL or SCCA cytology diagnoses had significantly higher percentages of cells with 3q26 gain than did patients with NILM or ASC-US cytologic diagnoses.

CONCLUSIONS

FISH can be performed on cervicovaginal liquid-based preparations to detect gain of 3q26. Gain of 3q26 is associated with HSIL and SCCA. This test may be an adjunct to cytology screening, especially high-risk patients.

Association between the stages of cervical cancer and chromosome 1 aneusomy

The high-risk human papillomavirus is known to play a pivotal role in cervical carcinogenesis. Numerical and structural aberrations are known to be related to different behaviors of malignant cervical lesions. The aims of this study were (1) to assess the number of cervical cells with chromosome 1 aneusomy (monosomy, trisomy, and tetrasomy) in 20 women with cervical intraepithelial neoplasia (CIN 1, CIN 2, CIN 3, and invasive cancer) and three women without CIN by fluorescence in situ hybridization (FISH), (2) to determine the heterogeneity of aneusomy among women within each of the five groups studied, (3) to determine the association between the four progressive stages of cervical cancer and the number of cells with and without aneusomy, (4) to determine the association between number of cells with and without aneusomy and human papilloma virus (HPV) infection, and (5) to determine its usefulness as a biomarker of cancer risk. A hospital-based unmatched case-control study in a sample of 23 women grouped by disease stage and selected by histology from the Obstetrics and Gynecology Hospital of the Instituto Mexicano del Seguro Social (IMSS) in Mexico was conducted in 2002. Numerical aberrations of chromosome 1 in cervical smears were detected with FISH. HPV was detected with polymerase chain reaction (PCR) and typing was performed with restriction fragment length polymorphism (RFLPs). Analysis of chromosome 1 aneusomy revealed (1) homogeneity among women within each one of the five groups, (2) a positive linear trend between the aneusomy frequency and grade of lesion, and (3) an association between aneusomy and high-risk HPV infection. These findings suggest the usefulness of the number of cervical cells with chromosome 1 aneusomy as a biomarker. In order to validate this biomarker we suggest a larger prospective study of cytological samples of patients with a longer follow-up.

Sensitive detection of tumour cells in effusions by combining cytology and fluorescence in situ hybridisation (FISH)

Diagnosis of malignant cells in effusions is important for staging procedures and resulting therapeutic decisions. Cytodiagnostics in effusions is sometimes difficult since reactive mesothelial cells can mimic malignant cells. We used fluorescence in situ hybridisation (FISH) in single-colour or if appropriate in dual-colour evaluation to detect chromosomal aberrations in effusion cells as markers of malignancy, to raise the diagnostic yield. Cytologic and FISH evaluations – by using probes representing several chromosomes always including chromosomes 11 and 17 – were performed in 358 effusion fluids. Cytology was positive for malignancy in 44.4% of all effusions, whereas FISH was positive in 53.9% (P=0.0001). The combination of cytology and FISH was diagnostic for malignancy in 60.9% of effusions. Diagnostic superiority of FISH was demonstrated in effusions from breast cancer, lung cancer, pancreatic cancer, and in effusions from the entire group of gynaecological and gastrointestinal carcinomas. In transudates (effusion protein <2.5 g dl⁻¹), malignant cells were detectable by cytology, FISH, and combined use of both methods in 18.6, 30, and 37.1% of effusions, respectively, suggesting that cytologic and molecular analysis should be performed also with transudates. In conclusion, FISH in combination with conventional cytology is a highly sensitive and specific diagnostic tool for detecting malignant cells in effusions.

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

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

E6 and E7 oncoproteins induce distinct patterns of chromosomal aneuploidy in skin tumors from transgenic mice

Inactivation of the tumor suppressor genes p53 and Rb are two of the most common genetic alterations in cancer cells. We use a mouse model to dissect the consequences of compromising the function of either of these genes on the maintenance of genomic stability. Thirteen cell lines established from skin tumors of mice expressing either the E6 or E7 oncoprotein of the human papillomavirus (HPV) type 16 under control of the keratin 14 promoter were analyzed by comparative genomic hybridization, spectral karyotyping and fluorescence in situ hybridization, reverse transcription-PCR, and mutation analysis. Deducing from the wealth of molecular cytogenetic data available from human cancers, we hypothesized that the more benign tumors in mice expressing E7 would be distinct from the more aggressive lesions in E6 transgenic mice. Tumorigenesis in E6-expressing mice required specifically the selection and maintenance of cells with extra copies of chromosome 6. Aneuploidy of chromosome 6 was independent of activating mutations in H-ras on chromosome 7. Expression of either E6 or E7 resulted in centrosome aberrations, indicating that each viral oncoprotein interferes independently with the centrosome cycle. Although centrosome aberrations are consistent with development of aneuploidy, no direct correlation was evident between the degree of aneuploidy and the percentage of cells with aberrant centrosomes. Our results show that although aneuploidy and centrosome aberrations are present in tumor cells from mice expressing either E6 or E7, tumorigenesis via E6 requires copy number increases of mouse chromosome 6, which is partially orthologous to human chromosome 3q, a region gained in HPV-associated carcinomas.

Detection of genomic amplification of the human telomerase gene (TERC) in cytologic specimens as a genetic test for the diagnosis of cervical dysplasia

Invasive cervical carcinomas frequently reveal additional copies of the long arm of chromosome 3. The detection of this genetic aberration in diagnostic samples could therefore complement the morphological interpretation. We have developed a triple-color DNA probe set for the visualization of chromosomal copy number changes directly in thin-layer cervical cytology slides by fluorescence in situ hybridization. The probe set consists of a BAC contig that contains sequences for the RNA component of the human telomerase gene (TERC) on chromosome band 3q26, and repeat sequences specific for the centromeres of chromosomes 3 and 7 as controls. In a blinded study, we analyzed 57 thin-layer slides that had been rigorously screened and classified as normal (n = 13), atypical squamous cells (ASC, n = 5), low-grade squamous intraepithelial lesions (LSIL, n = 14), and high-grade squamous intraepithelial lesions (HSIL) grade 2 (CIN2, n = 8), and grade 3 (CIN3, n = 17). The percentage of tetraploid cells (P(Trend) < 0.0005) and cells with multiple 3q signals increased with the severity of the cytologic interpretation (P(Trend) < 0.0005). While only few normal samples, ASC and LSIL lesions, revealed copy number increases of 3q, 63% of the HSIL (CIN2) lesions and 76% of the HSIL (CIN3) lesions showed extra copies of 3q. We conclude that the visualization of chromosome 3q copy numbers in routinely prepared cytological material using BAC clones specific for TERC serves as an independent screening test for HSIL and may help to determine the progressive potential of individual lesions.

Identification of numerical chromosomal changes detected by interphase fluorescence in situ hybridization in high-grade prostate intraepithelial neoplasia as a predictor of carcinoma

CONTEXT

High-grade prostate intraepithelial neoplasia (HPIN) is the most likely precursor of prostate cancer. The condition of many patients with a diagnosis of HPIN in prostate needle core biopsy could, if left untreated, progress to invasive cancer. Currently there is no available clinical, immunohistochemical, or morphologic criteria that are predictive of this progression.

OBJECTIVE

To determine whether chromosomal instability in these precursor lesions could increase their predictive value for cancer detection.

DESIGN

Dual-color interphase fluorescence in situ hybridization analysis was performed on archived prostate needle core biopsies from 54 patients with initial diagnosis of isolated HPIN and follow-up of 3 years or more. We used commercially available centromere probes for chromosomes 4, 7, 8, and 10. We had interpretable results in 44 patients as follows: (1) group A: 24 HPIN patients with persistent HPIN and/or benign lesions in the follow-up biopsies, and (2) group B: 20 HPIN patients with progression to prostate carcinoma.

RESULTS

Twenty-five percent of the patients in group B displayed numeric chromosomal aberrations. Only 8.3% of the patients from group A had chromosomal abnormalities (P =.1). The observed overall chromosomal changes in HPIN were higher than those in normal or hyperplastic epithelium, with a statistically significant difference (P <.05). All aberrations were detected in the form of chromosomal gain. Overall, the commonest aberration was gain of chromosome 8, followed by gains of chromosomes 7 and 10.

CONCLUSION

These results indicated that although no single numeric chromosomal abnormality could be assigned as a predictor of HPIN progression to carcinoma, the overall level of numeric chromosomal abnormalities shows a trend of elevation in HPIN patients whose condition subsequently progressed to carcinoma.

p53 Alteration and chromosomal instability in prostatic high-grade intraepithelial neoplasia and concurrent carcinoma: analysis by immunohistochemistry, interphase in situ hybridization, and sequencing of laser-captured microdissected specimens

p53 mutation has been shown to be associated with chromosomal instability (CI) in many human dysplastic and neoplastic lesions. However, the precise role of p53 in the pathogenesis of prostate carcinoma (Pca) is unknown. Topographic analysis of p53 alteration using immunohistochemistry (IHC) was performed on 35 archived prostatectomy specimens containing Pca foci; high-grade prostate intraepithelial neoplasia (HPIN) foci intermingled with cancer (HPINI) and situated away (HPINA). Specimens from 2 patients were topographically genotyped using laser capture microdissection, PCR amplification, and direct sequencing of p53 exons 5-9. CI was evaluated in the same tissue foci by interphase in situ hybridization (IFISH) using centromere probes for chromosomes 7, 8, and Y. p53 immunoreactivity was found in 20%, 17%, 0, and 0 in Pca, HPINI, HPINA, and benign epithelium, respectively. p53 molecular analysis in the specimens examined confirmed the IHC findings. IFISH revealed numerical chromosomal alterations in keeping with CI in 71% and 25% of p53+ and p53- Pca, respectively (P =.1), 67% and 0 of p53+ and p53- HPIN, respectively (P <.02), and in 27% and 0 of HPINI and HPINA, respectively. We concluded that p53 mutation is an early change in at least a subset of Pca. HPINI foci tend to have higher overall p53 immunoreactivity and CI than HPINA. The presence of p53 mutation in HPIN was associated with the presence of CI as determined by IFISH. Our study also provided additional evidence in support of the concept that HPIN might be the earliest precursor of cancer. Furthermore, our studies identify genomic similarities in HPINI and Pca, implying that carcinoma may arise from progression of certain HPIN foci that most likely harbor p53 mutation and/or more CI.

A newly characterized human endometrial adenocarcinoma cell line (CAC-1) differentiates in response to retinoic acid treatment

A new cell line of poorly differentiated human endometrial adenocarcinoma cells termed "CAC-1" cells has been established. These cells are epithelial, as indicated by positive cytokeratin and negative vimentin staining. They are rounded and possess a high nuclear-to-cytoplasmic ratio, desmosomes, surface microvilli, intercelular lumens, and pleomorphic nuclei containing multiple nucleoli. These cells have been in long-term culture for 2 years. Our previous studies demonstrated that moderately differentiated (RL95-2) cells differentiated in response to retinoic acid treatment, illustrated by their reorganization of actin filaments and cell enlargement (Carter et al., 1996; Anticancer Res. 16, 17-24). CAC-1 cells exhibited a similar response because they also organized actin filaments and enlarged in response to retinoic acid treatment. Concurrently, retinoic acid treatment caused a 40% decrease in cell detachment in an in vitro detachment assay compared to controls. A slight lag in cell growth was observed when CAC-1 cells were treated with 1 microM 13-cis or all-trans retinoic acid during a 12-day growth curve. In addition, we examined the effects of retinoic acid on protein kinase C-alpha (PKC-alpha) and myristoylated alanine-rich C-kinase substrate (MARCKS). Treatment with retinoic acid caused cytoplasmic PKC-alpha to increase concomitant with a decrease in PKC-alpha in the membrane. In contrast, MARCKS increased in the membrane in response to retinoic acid treatment. These data indicate that retinoid treatment causes inactivation of PKC-alpha, allowing MARCKS to relocalize to the membrane, where it can cross-link actin filaments. CAC-1 cells represent an ideal model for investigating the effects of retinoids on differentiation induction concomitant with actin reorganization.