Dynamics of Human Papillomavirus Infection between Biopsy and Excision of Cervical Intraepithelial Neoplasia: Results from the ZYC101a Protocol

BACKGROUND

Little is known about the dynamics of human papillomavirus (HPV) during the follow-up of cervical intraepithelial neoplasia (CIN) 2/3 after biopsy.

METHODS

A total of 127 women with biopsy-confirmed CIN2/3 were enrolled in a phase 2 double-blinded, randomized, placebo-controlled clinical trial of ZYC101a. Colposcopic, cytologic, and HPV testing were performed over the course of 6 months, before a loop electrical surgical excision procedure was performed at study exit.

RESULTS

Of the women tested, 99% were found to be HPV positive at study entry, 50% were found to be HPV type 16 positive at study entry, 22% were found to be positive for multiple HPV types at study entry, and 37% were found to be positive for additional HPV types during follow-up. Of those with a histologic outcome of CIN1 at study exit, 78% were found to be positive for additional HPV types; in 39%, the original type was replaced with a new HPV type. Virus load at study entry did not predict outcome, but pre-study-exit virus load correlated with a histologic outcome of any CIN, and changes in virus load correlated with risk for an outcome of CIN2/3 at study exit.

CONCLUSIONS

The type and number of HPVs at study entry, detection of additional viral types, and virus load changes during follow-up influence histologic outcome at study exit. An outcome of CIN1 at study exit is most likely due to additional HPV infections, rather than morphologic reversion of CIN2/3 to CIN1. Knowledge of the dynamics of HPV infection during the biopsy-to-excision period is critical to understanding the natural history of HPV infection, its contribution to disease outcome, and interpretations of drug efficacy.

Evidence Supporting the Current Management Guidelines for High-Grade Squamous Intraepithelial Lesion Cytology

OBJECTIVE

The study was undertaken to provide consensus guidelines for the management of women with a cytologic interpretation of high-grade squamous intraepithelial lesion (HSIL) on cytologic examination. This review article presents relevant literature supporting the proposed guidelines.

PARTICIPANTS

An independent panel of 121 experts in various aspects of the diagnosis and management of cervical cancer precursors, including representatives from 29 participating professional organizations, federal agencies, national and international health organizations, and others were invited by the American Society for Colposcopy and Cervical Pathology.

CONSENSUS PROCESS

Guidelines for the management of women with HSIL cytologic results were developed through a multistep process. Draft management guidelines were developed by the HSIL working group after formal literature reviews and obtained input from the professional community at large by way of an interactive internet-based bulletin board. At the American Society for Colposcopy and Cervical Pathology Consensus Conference, September 6 through 8, 2001, in Bethesda, Maryland, the guidelines were discussed, revised, and adopted by formal vote.

CONCLUSIONS

Evidence-based guidelines have been developed for the management of women with HSIL cytologic results.

Vaccines for cervical cancer

Human papillomaviruses (HPVs) are responsible for the nearly 450,000 cervical cancers that occur each year throughout the world. In the United States, the cancer rate is low (13,500 cases per year); nevertheless, HPVs affect millions of men and women annually in the form of genital warts and preinvasive diseases of the cervix and anogenital region. The expense of cancer prevention via precancer and cancer management is high, yet most HPV infections resolve spontaneously as a result of a successful host immune response. Recently, the discovery of methods to reproduce HPV virions (viral-like particles) in vitro has resulted in a successful clinical trial of preventing HPV infection and its associated precursor lesions. Although prevention is type-specific and duration of immunity is unknown, these results validate a vaccine strategy targeting prepubertal children that could prevent a significant proportion of genital warts and cervical precancers and cancers from occurring during reproductive life. Reversing advanced preinvasive and invasive cervical neoplasia with immunotherapeutics is a more difficult challenge, inasmuch as little or no evidence for natural immune-mediated regression of these diseases exists. Nonetheless, recent controlled trials have shown some success in inducing precursor regression with vaccines targeting viral oncoproteins. Anecdotal reports of therapies that augmentcellular immunity raise hopesthattherapeutics targeting multiple pathways of anti-viral or anti-tumor immunity will be beneficial to women with established cervical cancer. However, success will require identifying and circumventing the mechanisms by which tumor cells evade the immune system.

ZYC101a for treatment of high-grade cervical intraepithelial neoplasia: a randomized controlled trial

OBJECTIVE

The objective of this study was to assess the safety and efficacy of a novel therapeutic, ZYC101a, for the treatment of women with histologically confirmed cervical intraepithelial neoplasia (CIN) 2/3. ZYC101a contains plasmid-DNA-encoding fragments derived from the E6 and E7 proteins of human papillomavirus (HPV) 16 and 18, and is formulated within small biodegradable microparticles.

METHODS

A multicenter, double-blind, randomized, placebo-controlled trial was conducted in a group of women with biopsy-confirmed CIN 2/3. Subjects were randomized to 3 intramuscular doses of either placebo or ZYC101a (100 or 200 microg). Six months after the first injection, subjects underwent cervical conization. The primary endpoint for this study was histologically confirmed resolution of CIN 2/3. A total of 161 subjects were randomized, dosed, and evaluated for safety. After central pathology review, 127 subjects were evaluable for efficacy.

RESULTS

The most common adverse events were related to the injection site, were mild to moderate, and did not worsen at later treatments. The proportion of subjects who resolved was higher in the ZYC101a groups compared to placebo (43% versus 27%), but the difference was not statistically significant (P =.12). In a prospectively defined population of women younger than 25 years (n = 43), resolution was significantly higher in the combined ZYC101a groups compared to placebo (70% versus 23%; P =.007). ZYC101a activity was not restricted to HPV-16-or HPV-18-positive lesions.

CONCLUSIONS

ZYC101a was shown to be well tolerated in all patients and to promote the resolution of CIN 2/3 in women younger than 25 years.

LEVEL OF EVIDENCE

I

Prognostic significance of lymph node variables and human papillomavirus DNA in invasive vulvar carcinoma

OBJECTIVE

The present study investigates the influence of lymph node pathological features and HPV DNA status on the prognosis of vulvar invasive tumors.

METHODS

This study includes 184 consecutive cases of primary invasive squamous cell carcinoma of the vulva treated by radical surgery from 1975 to 1992, in São Paulo, Brazil. Clinical follow-up data was collected from patient files and hematoxilin-eosin sections were reviewed. HPV detection and typing was done by polymerase chain reaction (PCR), using specific and generic primers, followed by dot blot hybridization (DBH) with type-specific oligonucleotide probes for 19 HPV types. Age-adjusted Kaplan-Meier survival curves and Cox proportional hazards models were used to analyze the cancer risk associations for all DNA and pathology-related variables.

RESULTS

Among 161 cases tested by PCR, 38 (23.6%) were positive for high-risk HPV types. Regional lymph nodes of 43 cases, including all those of HPV-positive tumors and a sample of the ones removed from patients with HPV negative tumors, were evaluated by the same method. HPV DNA was found in the lymph nodes of 10 cases. In every case, at least one lymph node was metastatic and the HPV detected in the lymph nodes were of the same type as those found in the primary tumor in all cases. Multivariate analysis including age, race, pattern of invasion, tumor thickness, inflammatory reaction, surgical margins, number of node metastases, presence of extracapsular growth, depth of invasion, and presence of high-risk HPV DNA was performed. Following automated selections of this model, node variables important for prognosis that remained were number of node metastases and presence of extracapsular growth.

CONCLUSIONS

Patients with four or more node metastases associated with extracapsular spread were 5.6 (95%CI: 2.3-13.1) times more likely to die from cancer and 10.0 (95%CI: 4.0-24.9) times more likely to have a recurrence than patients without metastases. The HPV status in the tumor was not important as a prognostic factor.

Atypical glandular cells of undetermined significance. Outcome predictions based on human papillomavirus testing

Cases of atypical glandular cells (AGC) diagnosed on liquid-based preparations were culled from a 3-year period. When available, residual cellular material was analyzed for human papillomavirus (HPV) by polymerase chain reaction and correlated with cytologic and histologic (biopsy) outcome. Of 178,994 cytologic cases, 187 (0.1045%) contained AGC compared with 8,740 (4.8828%) atypical squamous cells (ASC) for an AGC/ASC ratio of 0.021. HPV results and follow-up were available for 108 specimens from 106 patients. Depending on the end-point (histologic/cyto-logic), the sensitivity range of HPV testing for significant cervical disease (high-grade squamous intraepithelial lesion [SIL], adenocarcinoma in situ [ACIS], invasive carcinoma) was 83% with a specificity range of 78% to 82%, a positive predictive value of 57% to 61%, and a negative predictive value of 91% to 95%. Fifteen false-positive results included concurrent ASC or low-grade SIL, ASC on follow-up cytology, and previous ACIS with a negative follow-up cone biopsy result. Noncervical glandular neoplasia (including atypical endometrial hyperplasia) was confirmed in 13 cases (1 recurrent), only 2 of which scored positive for HPV. HPV-positive AGC has a substantially higher positive predictive value for significant disease than ASC (61% vs historic 20%) and merits consideration in the triage of patients with atypical endocervical cells not otherwise specified. However, noncervical or other HPV-negative glandular neoplasia must be considered in all patients with AGC, particularly older patients.

Hertig and beyond: a systematic and practical approach to the endometrial biopsy

Evaluation of the endometrial biopsy is a challenge to practicing pathologists, largely due to the wide range of morphologic patterns resulting from both normal and abnormal cyclic changes, exogenous hormones, infections, and intrauterine tumors. Successfully addressing these challenges requires that the practitioner (i) understand the clinical questions being asked, (ii) have a realistic expectation for answering these questions, and (iii) have a systematic approach to resolving these questions in the context of these expectations. The approach outlined begins with the subdividing of women with endometrial alterations into three general categories: (i) women in their fourth decade undergoing evaluation for infertility, (ii) women in their fifth decade who experience abnormal uterine bleeding, and (iii) women in their sixth decade and beyond who experience postmenopausal bleeding. The clinical expectations for each group are unique, as are the morphologic patterns most commonly encountered. Algorithms for the laboratory management of cyclic changes, dysfunctional bleeding, and mixed-pattern endometria are provided, as are pitfalls in interpretation and exclusion of neoplasia.

Innovations in understanding the biology of cervical cancer

Revelation of the connection between the human papillomavirus (HPV) and cervical neoplasia and invasive cervical cancer is prompting new investigations to expand that understanding and promote vaccines, gene therapy, and other interventions. At the Second International Conference on Cervical Cancer (Houston, TX, April 11-14, 2002), laboratory and clinical researchers reported advances in new studies meant to increase understanding of the natural history of HPV and cervical intraepithelial neoplasia, to evaluate new cervical cancer screening techniques, and to promote new therapies. Using K14-HPV type 16 transgenic mice, researchers are investigating the effects of estrogen on cervical cancer carcinogenesis, and results are lending support to epidemiological theories showing a difference in HPV infection rates and the development of cervical lesions in women using oral contraceptives. Other work involves investigating genes that are up-regulated by HPV infection and the role of the p53 homologue, p63, in cervical neoplasia evolution. Telomerase also is under investigation as a biomarker in high-risk populations. Gene therapy that replaced p53 in cervical cancer cell lines in vitro and a nude mouse model inhibited cell and tumor growth, confirming previous findings in squamous epithelial carcinomas of the head and neck. Furthermore, research in intracellular targeting of antigens to subcellular locations shows promise for treating cervical cancer preclinically. Identification of molecular changes in cervical cancer and knowledge about the importance of HPV infection in cervical cancer can lead to new therapies to treat existing cervical cancer and, in the long term, prevent the disease.

The significance of the Papanicolaou smear diagnosis of low-grade squamous intraepithelial lesion cannot exclude high-grade squamous intraepithelial lesion

BACKGROUND

Cervical cytologic specimens that show a low-grade squamous intraepithelial lesion (LSIL) occasionally contain a few cells that are suspicious for, but not diagnostic of, a high-grade squamous intraepithelial lesion (HSIL). In such cases, a diagnosis of LSIL cannot exclude HSIL is rendered. The objective of the current study was to assess the positive predictive value (PPV) for HSIL in follow-up cervical biopsies for these cases.

METHODS

One hundred forty-four women with a Papanicolaou (Pap) diagnosis of LSIL cannot exclude HSIL and their follow-up cervical biopsies were reviewed. Results were compared with a control group of 155 women with a Pap diagnosis of LSIL. A subset of biopsies was tested and typed for human papillomavirus (HPV) DNA by polymerase chain reaction amplification using consensus primers followed by restriction fragment length polymorphism analysis. HPVs were scored as low-risk or high-risk types.

RESULTS

Women with LSIL cannot exclude HSIL had a higher incidence of HSIL (PPV = 29%) on follow-up cervical biopsy than the control group (PPV = 15%, P < 0.01). In addition, SIL, indeterminate grade was diagnosed in 10% of cervical biopsies in the study group as compared with 4% in controls. Review of Pap smears from the study group showed that there were 3 types of cells suspicious for a high-grade lesion: atypical squamous metaplastic cells (62%), atypical keratinized cells (20%), and dysplastic cells of borderline nuclear-to-cytoplasm ratio (18%). HPV analysis confirmed the presence of high-risk HPV types in the study cases with high-grade cervical biopsies.

CONCLUSIONS

Women with a Pap diagnosis of LSIL cannot exclude HSIL appear to be more likely to harbor a high-grade lesion than those diagnosed with LSIL alone. Its use appears warranted. Women with this diagnosis merit appropriate clinical follow-up to exclude HSIL.

Co-expression of p16(INK4A) and laminin 5 gamma2 by microinvasive and superficial squamous cell carcinomas in vivo and by migrating wound and senescent keratinocytes in culture

The high frequency of mutation, deletion, and promoter silencing of the gene encoding p16(INK4A) (p16) in premalignant dysplasias and squamous cell carcinomas (SCC) of epidermis and oral epithelium classifies p16 as a tumor suppressor. However, the point during neoplastic progression at which this protein is expressed and presumably impedes formation of an SCC is unknown. Induction of p16 has been found to be responsible for the senescence arrest of normal human keratinocytes in culture, suggesting the possibility that excessive or spatially abnormal cell growth in vivo triggers p16 expression. We examined 73 skin and oral mucosal biopsy specimens immunohistochemically to test this hypothesis. p16 was not detectable in benign hyperplastic lesions, but instead was expressed heterogeneously in some dysplastic and carcinoma in situ lesions and consistently at areas of microinvasion and at superficial margins of advanced SCCs. p16-positive cells in these regions coexpressed the gamma2 chain of laminin 5, identified previously as a marker of invasion in some carcinomas. Normal keratinocytes undergoing senescence arrest in culture proved to coordinately express p16 and gamma2 and this was frequently associated with increased directional motility. Keratinocytes at the edges of wounds made in confluent early passage cultures also coexpressed p16 and gamma2, accompanying migration to fill the wound. These results have identified the point during neoplastic progression in stratified squamous epithelial at which the tumor suppressor p16 is expressed and suggest that normal epithelia may use the same mechanism to generate non-dividing, motile cells for wound repair.

Immunophenotypic and viral (human papillomavirus) correlates of vulvar seborrheic keratosis

Human papillomavirus (HPV) infections of the genital mucosa classically present as warts (condylomata) and are traditionally defined by the presence of viral cytopathic effect (koilocytosis). In recent years, HPV has been detected in vulvar epithelial changes lacking koilocytosis, including squamous papillomas and lesions closely resembling seborrheic keratosis (SK). The purpose of this study was to determine the frequency and type of HPV associated with vulvar SK (VSK) and to compare expression of biomarkers (p16, Mib-1, and cyclin E) in these lesions. Sixty-seven biopsy specimens, including 25 VSKs, 10 nondiagnostic vulvar acanthoses, 12 fibroepithelial polyps (FEPs), and 20 nongenital cutaneous SKs (CSKs), were studied. Biopsy specimens were typed for HPV by polymerase chain reaction and immunostained with Mib-1, cyclin E, and p16(INK4) antibodies. Eighteen of 25 VSKs (72%), 0 of 10 nondiagnostic vulvar acanthuses (0%; P = 0.0001), 2 of 12 FEPs (16.7%; P = 0.004), and 3 of 20 CSKs (15%; P = 0.0002) scored HPV positive. Increased Mib-1 staining was significantly more common in VSKs than in other vulvar lesions, but not in CSKs; increased p16 and cyclin E staining was not more common. VSKs are morphologically and immunophenotypically similar to CSKs but distinct by their association with HPV. Unlike the cervix, p16 and cyclin E will not consistently distinguish VSKs from HPV-negative lesions due to underexpression in low-risk HPV infections (p16) and less-restricted expression in vulvar lesions (cyclin E). Whether CSKs are associated with other forms of HPV infection remains to be determined.

Cervical cancer screening: from the Papanicolaou smear to the vaccine era

In the next 20 years, cervical cancer screening will have evolved through four phases. The first was traditional screening, which has been associated with a two-thirds reduction in cancer incidence and death rates in the last 50 years and currently is ending. We are entering a second phase, human papillomavirus (HPV) testing, for managing cytologic abnormalities and possibly for primary screening. A third phase, new in development, proposes the use of host biomarkers (or combinations thereof) as either surrogates of HPV infection or, potentially, indicators to assess cancer risk and concentrate available resources on a subset of women. The fourth and, likely, final phase will be screening in an era of vaccines. If HPV vaccines are successful, the pool of at-risk individuals and the prevalence of papillomaviruses that place them at risk will gradually shrink. In this climate, screening strategies that target HPVs alone (as opposed to cytologic testing) may become more economical. If so, previous strategies may become obsolete as the balance of cervical cancer prevention shifts from traditional screening to primary prevention coupled with HPV testing.

Immunotherapy of human cervical high-grade cervical intraepithelial neoplasia with microparticle-delivered human papillomavirus 16 E7 plasmid DNA

OBJECTIVE

The purpose of this study was to evaluate the safety of the administration of a bacterial expression plasmid encoding a 13 amino acid sequence that is highly homologous with human papillomavirus E7 within poly (lactide-co-glycolide) microparticles (ZYC101) in women with HLA A2+ antigen and persistent cervical intraepithelial neoplasia grade 2/3 and human papillomavirus 16.

STUDY DESIGN

Fifteen women entered an institutional review board-approved dose-escalating phase I study with the use of three levels of blood monitoring and urine studies, Papanicolaou tests, and colposcopy. Escalation required no serious adverse events. Immunologic responses were evaluated in peripheral blood with the use of human papillomavirus peptide-stimulated interferon gamma enzyme-linked immunosorbent assay for T-cell reactivity. In cervical secretions, immunoglobulin A anti-human papillomavirus 16 E2 concentrations were measured. Three doses every 3 weeks were followed 4 weeks later by surgical excision.

RESULTS

No serious adverse events occurred. Five women had complete histologic responses; 11 women had human papillomavirus-specific T-cell responses. Four of five complete histologic responses developed immunoglobulin A anti-E2-specific antibody.

CONCLUSION

ZYC101 warrants further investigation because of a 33% complete histologic responses, a 73% immunologic response, and no serious adverse events.

Biomarkers in diagnostic obstetric and gynecologic pathology: a review

Until recently, the histologic diagnosis of obstetrical and gynecologic neoplasia was based principally on morphologic criteria. However, interobserver reproducibility for entities such as squamous intraepithelial, endometrial, and trophoblastic disease varies widely between observers. This inherent variability in interpretation between individuals has led to wide ranges in diagnostic precision between practices, and in many cases, between recognized experts. The advent of immunohistochemistry, and the more recent accelerated discovery of new genes and their functions has resulted in the discovery of cellular proteins or nucleic acids that are differentially expressed in tumors. When applied in conjunction with existing histologic criteria, these "biomarkers" have the potential to enhance diagnostic consistency and reproducibility. The gains expected are to practicing diagnostic pathologists (who will enjoy greater diagnostic consistency) and to academics (for whom biomarkers may uncover new pathways unappreciated by histologic diagnosis alone). However, fundamental to the success in both arenas will be critical analysis of the potential pitfalls in immunohistochemistry, strict validation of new markers as they arrive in the field, and a realistic view of their value in the laboratory management of obstetrical and gynecologic diseases.

Symposium part 1: Should the Bethesda System terminology be used in diagnostic surgical pathology?: Point

During the past 50 years, the histologic classification of cervical intraepithelial neoplasia (CIN) has evolved to incorporate the entire spectrum of genital papillomavirus infections, segregating those lesions with the higher risk of containing prototypic high-risk human papillomavirus types, and recently has meshed with treatment algorithms that include loop electrical excision procedures and follow-up alone. This review describes a classification system that divides CIN into categories of low-grade (CIN 1) and high-grade (CIN 2 and CIN 3). To successfully apply this system, the practitioner must efficiently exclude nonneoplastic entities and base the distinction of CIN 1 from CIN 2/3 on criteria that recognize the effects of viral oncogenes on replicating cells. This is achieved by basing the diagnosis of CIN 1 on uniform polarized epithelial growth, low mitotic index, low mitotic counts, and minimal parabasal cell anisokaryosis and coarse chromatin and CIN 2 on the presence of these features or abnormal mitoses. Simply put, the definition of CIN 2 (or higher) is the presence of atypical immature cells in the biopsy that if seen in a cytologic smear would merit a diagnosis of high-grade squamous intraepithelial lesion. In essence, a successful two-grade system requires careful application of cytologic criteria in a histologic milieu. This model is illustrated in a set of 25 images that underscore the importance of excluding benign changes (with the appropriate use of biomarkers), segregating unusual variants of low-grade squamous intraepithelial lesions, and identifying the morphologic transition to high-grade squamous intraepithelial lesions (CIN 2 or CIN 3) with an acceptable level of reproducibility.

Loss of p63 expression is associated with tumor progression in bladder cancer

p63, a member of the p53 gene family, encodes multiple proteins that may either transactivate p53 responsive genes (TAp63) or act as a dominant-negative factor toward p53 and p73 (Delta Np63). p63 is expressed in many epithelial compartments and p63(-/-) mice fail to develop skin, prostate, and mammary glands among other defects. It has been previously shown that p63 is expressed in normal urothelium. This study reports that p63 is regulated in bladder carcinogenesis and that p63 expression is lost in most invasive cancers whereas papillary superficial tumors maintain p63 expression. Examination of bladder carcinoma cell lines reveals that certain lines derived from invasive carcinomas maintain expression of Delta Np63, as demonstrated by both immunoblotting and confirmed by isoform-specific quantitative reverse transcriptase-polymerase chain reaction. Another novel finding reported in this study is the fact that p63(-/-) mice develop a bladder mucosa epithelial layer yet fail to complete uroepithelial differentiation, producing a nontransitional default cuboidal epithelium. These data indicate that in contrast to the skin and prostate, p63 is not required for formation of a bladder epithelium but is indispensable for the specific differentiation of a transitional urothelium.

p63 Coordinates anogenital modeling and epithelial cell differentiation in the developing female urogenital tract

p63 is a p53 homologue required for cutaneous development that is expressed in immature squamous epithelium and reserve cells of the cervix. Humans with p63 mutations exhibit defects in limb, accessory organ (skin appendage, breast, prostate), and genitourinary development. Because p63 expression patterns imply a strong role of the gene in the female genital tract development, newborn female p63-/-, +/-, and +/+ mice were examined in situ, dissected, and compared. Nuclear p63 protein was localized to the skin, vagina, bladder, urethra, and basal columnar cells of the caudal uterus in p63+/+ and +/- animals. p63-/- mice exhibited abnormal genital morphogenesis with hypoplastic genitalia, a single cloacal opening, and persistence of columnar epithelium at lower genital tract sites that normally undergo squamous and urothelial differentiation. The defects observed support p63-dependent pathways of genital tract development that permit externally, ectodermal basal cell replenishment integral to reciprocal epithelial stromal signaling, urorectal septation, and modeling of the external genitalia; and internally, the emergence of basal epithelial cell populations capable of divergent epithelial cell differentiation in the vagina, cervix, and urinary tract. Defects in the first pathway explain imperforate anus, vaginal septum, genital hypoplasia, and micropenis reported in humans with p63 mutations. The second is necessary for the generation of multipotential reserve cells in the cervix and may be operative in other epithelial stromal interactions integral to the emergence of uterine basal cells later in life.

Human papillomaviruses, expression of p16, and early endocervical glandular neoplasia

Adenocarcinoma in situ (ACIS) is the precursor of cervical adenocarcinoma (ACs), and its distinction from benign but morphologically atypical glandular epithelium may be difficult. The cyclin-dependent kinase inhibitor p16(ink4) is expressed in cervical squamous cell carcinomas, their precursors, and cervical ACs, and there is a strong relationship between p16 expression and the presence of human papillomavirus (HPV)-encoded E6/E7 transcription. This study analyzed 95 cases of benign and premalignant cervical glandular ACIS lesions for p16 antigen and the proliferative marker Ki-67; HPV E6/E7 transcripts were detected by RNA/RNA in situ hybridization. HPV 16 or 18 E6/E7 transcription and strong, diffuse p16 positivity were detected only in ACIS lesions. A high and moderate Ki-67 index was observed in 76% and 22% of ACIS, respectively. Thirty-three of 36 microglandular change, tubal, atypical tubal, and endometrial-type epithelia scored negative or weakly positive for p16. Distribution of staining in 3 strongly positive cases was heterogeneous. The diffuse distribution of p16 immunostaining in HPV16/18-positive glandular neoplasms supports a strong association with HPV infection and indicates that this biomarker may discriminate ACIS from its benign mimics. However, this distinction requires attention to staining distribution because p16 is focally expressed in tubal-endometrial epithelia and diffusely expressed in endometrium, indicating that in some cases the use of other biomarkers, such as Ki-67, may be necessary. Because endometrial glandular epithelia may also express p16, the diagnostic application of p16 immunohistochemistry to cytological samples is uncertain.

Specific down-modulation of Notch1 signaling in cervical cancer cells is required for sustained HPV-E6/E7 expression and late steps of malignant transformation

The Notch family of cell surface receptors plays a key role in cell-fate determination and differentiation, functioning in a cell- and context-specific manner. In mammalian cells, Notch activation is generally thought to maintain stem cell potential and inhibit differentiation, thereby promoting carcinogenesis. However, in other contexts such as primary epithelial cells (keratinocytes), increased Notch activity causes exit from the cell cycle and/or commitment to differentiation. We now report that expression of the endogenous Notch1 gene is markedly reduced in a panel of cervical carcinoma cells whereas expression of Notch2 remains elevated, and Notch1 expression is similarly reduced or absent in invasive cervical cancers. Conversely, expression of activated Notch1 causes strong growth inhibition of HPV-positive, but not HPV-negative, cervical carcinoma cells, but exerts no such effects on other epithelial tumor cells. Increased Notch1 signaling, but not Notch2, causes a dramatic down-modulation of HPV-driven transcription of the E6/E7 viral genes, through suppression of AP-1 activity by up-regulation of the Fra-1 family member and decreased c-Fos expression. Thus, Notch1 exerts specific protective effects against HPV-induced transformation through suppression of E6/E7 expression, and down-modulation of Notch1 expression is likely to play an important role in late stages of HPV-induced carcinogenesis.