Molecular Basis for Advances in Cervical Screening

Cervical Cytology Biobanking in Europe

A cervical cytology biobank (CCB) is an extension of current cytopathology laboratory practice consisting in the systematic storage of Pap smears or liquid-based cytology samples from women participating in cervical cancer screening with the explicit purpose to facilitate future scientific research and quality audit of preventive services. A CCB should use an internationally agreed uniform cytology terminology, be integrated in a national or regional screening registry, and be linked to other registries (histology, cancer, vaccination). Legal and ethical principles concerning personal integrity and data safety must be respected strictly. Biobank-based studies require approval of ethical review boards.

A CCB is an almost inexhaustible resource for fundamental and applied biological research. In particular, it can contribute to answering questions on the natural history of HPV infection and HPV-induced lesions and cancers, screening effectiveness, exploration of new biomarkers, and surveillance of the short- and long-term effects of the introduction of HPV vaccination. To understand the limitations of CCB, more studies are needed on the quality of samples in relation to sample type, storage procedures, and duration of storage.

Investigating Diagnostic Problems of CIN1 and CIN2 Associated With High-risk HPV by Combining the Novel Molecular Biomarker PanHPVE4 With P16INK4a

Grading cervical intraepithelial neoplasia (CIN) determines clinical management of women after abnormal cytology with potential for overdiagnosis and overtreatment. We studied a novel biomarker of human papillomavirus (HPV) life-cycle completion (panHPVE4), in combination with the minichromosome maintenance (MCM) protein cell-cycle marker and the p16INK4a transformation marker, to improve CIN diagnosis and categorization. Scoring these biomarkers alongside CIN grading by 3 pathologists was performed on 114 cervical specimens with high-risk (HR) HPV. Interobserver agreement for histopathology was moderate (κ=0.43 for CIN1/negative, 0.54 for CIN2/≤CIN1, and 0.36 for CIN3). Agreement was good or excellent for biomarker scoring (E4: κ=0.896; 95% confidence interval [CI]: 0.763-0.969; p16INK4a : κ=0.798; 95% CI: 0.712-0.884; MCM: κ=0.894; 95% CI: NC (this quantity cannot be calculated). Biomarker expression was studied by immunofluorescence and immunohistochemistry and was correlated with 104 final CIN diagnoses after histologic review. All 25 histologically negative specimens were p16INK4a and panHPVE4 negative, although 9 were MCM-positive. There were variable extents of p16INK4a positivity in 11/11 CIN1 and extensive panHPVE4 staining in 9/11. Ten CIN2 lesions expressed panHPVE4 and p16INK4a, and 13 CIN2 expressed only p16INK4a. CIN3 showed extensive p16INK4a positivity with no/minimal panHPVE4 staining. PanHPVE4, unlike MCM, distinguished CIN1 from negative. PanHPVE4 with p16INK4a separated CIN2/3 showing only expression of p16INK4a, indicating transforming HR-HPV E7 expression, from CIN1/2 showing completion of HR-HPV life cycle by E4 expression and variable p16INK4a expression. PanHPVE4 and p16INK4a staining are complementary markers that could provide simple, reliable support for diagnosing CIN. Their value in distinguishing CIN1/2 that supports HR-HPV life-cycle completion (and which might ultimately regress) from purely transforming CIN2/3 needing treatment warrants further research.

Stratification of HPV-induced cervical pathology using the virally encoded molecular marker E4 in combination with p16 or MCM

High-risk human papillomavirus (HPV) types cause cervical lesions of varying severity, ranging from transient productive infections to high-grade neoplasia. Disease stratification requires the examination of lesional pathology, and possibly also the detection of biomarkers. P16(INK4a) and MCM are established surrogates of high-risk HPV E6/E7 activity, and can be extensively expressed in high-grade lesions. Here we have combined these two cellular biomarkers with detection of the abundant HPV-encoded E4 protein in order to identify both productive and transforming lesions. This approach has allowed us to distinguish true papillomavirus infections from similar pathologies, and has allowed us to divide the heterogeneous CIN2 category into those that are CIN1-like and express E4, and those that more closely resemble nonproductive CIN3. To achieve this, 530 lesional areas were evaluated according to standard pathology criteria and by using a multiple staining approach that allows us to superimpose biomarker patterns either singly or in combination onto an annotated hematoxylin and eosin (H&E) image. Conventional grading of neoplasia was established by review panel, and compared directly with the composite molecular pathology visualized on the same tissue section. The detection of E4 coincided with the onset of vacuolation, becoming abundant in koilocytes as the MCM marker declined and cells lost their defined nuclear margins as visualized by standard H&E staining. Of the dual marker approaches, p16(INK4a) and E4 appeared most promising, with E4 generally identifying areas of low-grade disease even when p16(INK4a) was present. Extensive p16(INK4a) expression usually coincided with an absence of E4 expression or its focal retention in sporadic cells within the lesion. Our results suggest that a straightforward molecular evaluation of HPV life-cycle deregulation in cervical neoplasia may help improve disease stratification, and that this can be achieved using complementary molecular biomarker pairs such as MCM/E4 or, more promisingly, p16(INK4a)/E4 as an adjunct to conventional pathology.

The E4 protein; structure, function and patterns of expression

The papillomavirus E4 open reading frame (ORF) is contained within the E2 ORF, with the primary E4 gene-product (E1^E4) being translated from a spliced mRNA that includes the E1 initiation codon and adjacent sequences. E4 is located centrally within the E2 gene, in a region that encodes the E2 protein's flexible hinge domain. Although a number of minor E4 transcripts have been reported, it is the product of the abundant E1^E4 mRNA that has been most extensively analysed. During the papillomavirus life cycle, the E1^E4 gene products generally become detectable at the onset of vegetative viral genome amplification as the late stages of infection begin. E4 contributes to genome amplification success and virus synthesis, with its high level of expression suggesting additional roles in virus release and/or transmission. In general, E4 is easily visualised in biopsy material by immunostaining, and can be detected in lesions caused by diverse papillomavirus types, including those of dogs, rabbits and cattle as well as humans. The E4 protein can serve as a biomarker of active virus infection, and in the case of high-risk human types also disease severity. In some cutaneous lesions, E4 can be expressed at higher levels than the virion coat proteins, and can account for as much as 30% of total lesional protein content. The E4 proteins of the Beta, Gamma and Mu HPV types assemble into distinctive cytoplasmic, and sometimes nuclear, inclusion granules. In general, the E4 proteins are expressed before L2 and L1, with their structure and function being modified, first by kinases as the infected cell progresses through the S and G2 cell cycle phases, but also by proteases as the cell exits the cell cycle and undergoes true terminal differentiation. The kinases that regulate E4 also affect other viral proteins simultaneously, and include protein kinase A, Cyclin-dependent kinase, members of the MAP Kinase family and protein kinase C. For HPV16 E1^E4, these kinases regulate one of the E1^E4 proteins main functions, the association with the cellular keratin network, and eventually also its cleavage by the protease calpain which allows assembly into amyloid-like fibres and reorganisation of the keratin network. Although the E4 proteins of different HPV types appear divergent at the level of their primary amino acid sequence, they share a recognisable modular organisation and pattern of expression, which may underlie conserved functions and regulation. Assembly into higher-order multimers and suppression of cell proliferation are common to all E4 proteins examined. Although not yet formally demonstrated, a role in virus release and transmission remains a likely function for E4.

Immunohistochemical detection of human papillomavirus capsid proteins L1 and L2 in squamous intraepithelial lesions: potential utility in diagnosis and management

While cervical cancer screening relies on cervical cytology and high-risk human papillomavirus (HPV) detection, the histologic diagnosis, and specifically lesion grade, is the main parameter that drives clinical management of screen-positive women. Morphologically diagnosed squamous intraepithelial lesions (SIL/CIN) regress spontaneously in more than half of the cases, but identifying those likely to persist and progress is not currently possible based upon morphology. Lack of major capsid protein L1 expression has been suggested as a feature in progressive lesions, whereas expression of the minor capsid protein L2 has not been extensively evaluated. The goal of this study is to evaluate immunohistochemical expression of L1 and L2 in SILs in correlation with lesion grade. A total of 150 cervical specimens with SILs were selected based on HPV 16 or HPV 18 detection by Q-PCR. These included 89 low-grade SILs (LSIL/CIN 1) and 123 high-grade SILs (75 HSIL/CIN 2 and 48 HSIL/CIN 3). More than one lesion/grade was identified in 53 specimens. The presence and grade of SIL was determined by a panel of pathologists. Capsid protein expression was assessed by immunohistochemistry using MAB 837 for L1 and RG-1 for L2. Lesions of different grades in the same specimen were scored separately. Expression of capsid proteins was detected in 34/89 (40%) LSIL/CIN 1, 5/75 (6%) HSIL/CIN 2 and none of 48 HSIL/CIN 3. L1 and L2 were co-expressed in the same area of the lesion in 22 cases. In addition, L1 alone was expressed in 6 lesions and L2 alone in 11 lesions. Among the cases with multiple lesion grades in the same specimen, none with HSIL/CIN 3 expressed capsid proteins in any portion/grade of the lesion. HPV capsid proteins are expressed almost exclusively in LSIL/CIN 1 and rarely in HSIL/CIN 2. Additional studies are warranted to examine lack of L1 and L2 expression in LSIL/CIN 1 as a predictor of persistence or progression to HSIL/CIN 3, the precursor of cervical cancer.

Human papillomavirus proteins as prospective therapeutic targets

Human papillomaviruses (HPV) are the causative agents of a subset of cervical cancers that are associated with persistent viral infection. The HPV genome is an ∼8 kb circle of double-stranded DNA that encodes eight viral proteins, among which the products of the E6 and E7 open reading frames are recognized as being the primary HPV oncogenes. E6 and E7 are expressed in pre-malignant lesions as well as in cervical cancers; hence these proteins have been extensively studied as potential targets for HPV therapies and novel vaccines. Here we review the expression and functions of E6 and E7 in the viral vegetative cycle and in oncogenesis. We also explore the expression and functions of other HPV proteins, including those with oncogenic properties, and discuss the potential of these molecules as alternative therapeutic targets.

Colorectal cancer: current care, future innovations and economic considerations

For those involved in colorectal cancer management, the present day is an exciting time. There is a multitude of new techniques to be considered for early detection (screening). National population screening for 60-69-year olds in England is due to start this year. Also, minimally invasive surgical techniques and multimodal pathways of care are aiding faster recovery, and there are increasing options for both adjuvant and palliative therapies. This article summarizes how colorectal cancer is currently managed in the UK and discusses the developments that are in the early stages of clinical use or on the horizon. Current management is discussed in detail in the hope that innovators reading the article may identify areas for improvement and allow comparison of new interventions with what are currently the gold standards. As changes are moving so fast, this review will probably only relate to the next 10 years at most. It does not provide a detailed reference list to support all therapies but indicates the key publications that will enable more detailed reading.

Basics of cytology

This overview is intended to give a general outline about the basics of Cytopathology. This is a field that is gaining tremendous momentum all over the world due to its speed, accuracy and cost effectiveness. This review will include a brief description about the history of cytology from its inception followed by recent developments. Discussion about the different types of specimens, whether exfoliative or aspiration will be presented with explanation of its rule as a screening and diagnostic test. A brief description of the indications, utilization, sensitivity, specificity, cost effectiveness, speed and accuracy will be carried out. The role that cytopathology plays in early detection of cancer will be emphasized. The ability to provide all types of ancillary studies necessary to make specific diagnosis that will dictate treatment protocols will be demonstrated. A brief description of the general rules of cytomorphology differentiating benign from malignant will be presented. Emphasis on communication between clinicians and pathologist will be underscored. The limitations and potential problems in the form of false positive and false negative will be briefly discussed. Few representative examples will be shown. A brief description of the different techniques in performing fine needle aspirations will be presented. General recommendation for the safest methods and hints to enhance the sensitivity of different sample procurement will be given. It is hoped that this review will benefit all practicing clinicians that may face certain diagnostic challenges requiring the use of cytological material.

Human papillomavirus and molecular considerations for cancer risk

Human papillomaviruses (HPVs) are a major cause of cancer globally, including cervical cancer. The HPV 'early' proteins, E6 and E7, are the chief oncoproteins involved in cancer progression. These oncoproteins are more highly expressed in high-grade dysplasias and invasive cancer coincident with reduced viral DNA replication and reduced production of infective progeny virions. The E6 and E7 oncoproteins interact with several cellular proteins-classically TP53 and RB1, respectively-leading to the degradation of several of these proteins, although all interactions do not necessarily result in the degradation of a cellular protein. HPV infection is also associated with viral and host DNA methylation changes, many of which also occur in cancer types not associated with HPV infection. The E6 and E7 interactions with cellular proteins and DNA methylation changes are associated with changes in the integrity of key cellular pathways that regulate genomic integrity, cell adhesion, the immune response, apoptosis, and cell cycle control. The alterations in key cellular pathways may provide useful biomarkers to improve the sensitivity of current cancer screening methods, such as the Papanicolaou test. This review provides a detailed summary of the interactions of E6 and E7 with cellular proteins and alterations in cellular DNA methylation associated with HPV infection. The importance of molecular biomarkers to the clinical setting, underserved populations, and general public health is discussed.

Papanicolaou smear history in women with low-grade cytology before cervical cancer diagnosis

BACKGROUND

The purpose of the current study was to examine the screening histories of women diagnosed with invasive cervical cancer (ICC) in 2000 who had previous Papanicolaou (Pap) smears deemed to be unsatisfactory or with low-grade findings that did not lead to biopsy.

METHODS

A total of 252 Pap smears from 47 women taken between 1992 and 2000 were included in the study; 247 smears were reexamined at the laboratory of origin before the study and all 252 were then reexamined independently by 2 experienced cytotechnicians and 2 cytopathologists.

RESULTS

Of the 47 cases of ICC, 35 were squamous cell carcinoma, 10 were adenocarcinoma, and 2 were other types. On reexamination at the laboratory of origin, 24 cases were upgraded and in the study group 27 cases were upgraded to diagnoses requiring biopsy. On reexamination at the laboratory of origin, it was found that the first high-grade squamous intraepithelial lesion (HSIL) could have been diagnosed on average 4.2 years earlier than it was originally (95% confidence interval [95% CI], 3.3-5.1 years). On reexamination by the study group the first diagnosis of HSIL was made in smears dating from 5.4 years before the diagnosis of ICC (95% CI, 4.5-6.2 years).

CONCLUSIONS

The study confirms that unsatisfactory and low-grade Pap smears imply a risk of developing high-grade lesions at a later date and shows that in a screening program a subgroup of smears may be diagnosed as unsatisfactory or low grade despite the presence of high-grade findings that are detectable on reexamination.