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Biomedical subjects

Christopher P Crum

Publications and source records attributed to Christopher P Crum.

17 recordsLinked to original sources

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.

Biomarkers, Tumor↗

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.

Animals↗

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.

Adolescent↗

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.

Adult↗

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.

Female↗

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.

Biomarkers, Tumor↗

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.

Cell Transformation, Neoplastic↗

NAD(P)H and collagen as in vivo quantitative fluorescent biomarkers of epithelial precancerous changes.

During the development of neoplasia, epithelial tissues undergo biochemical and structural changes that can manifest in tissue fluorescence. There have been several reports on different in vivo fluorescence characteristics between normal and precancerous (dysplastic) tissues. However, it has been difficult to identify and quantify the origins of these changes, mainly because of distortions introduced in measured tissue fluorescence spectra by tissue scattering and absorption. Such distortions can be removed by combining information in simultaneously measured fluorescence and reflectance spectra. Thus, we can recover the intrinsic (undistorted) tissue fluorescence. In this report, we show that extraction of the intrinsic fluorescence allows us: (a) to determine the fluorescence spectra of NAD(P)H and collagen in an in vivo environment, and (b) to use these NAD(P)H and collagen spectra to describe, quantitatively, diagnostically significant biochemical changes between normal and dysplastic tissues. Specifically, by analyzing intrinsic fluorescence of human epithelial tissue as it becomes deoxygenated in vivo, we can resolve the fluorescence spectra of NAD(P)H and collagen, two of the major tissue fluorophores. This is important because fluorescence depends on the local environment of the chromophore. Then, we extract the intrinsic fluorescence spectra of sites from 35 patients with suspected cervical lesions and 7 patients with Barrett's esophagus and describe them accurately as a linear combination of NAD(P)H and collagen contributions. In both tissue cases, we find that low collagen and high NAD(P)H fluorescence characterizes the high-grade dysplastic lesions when compared with nondysplastic tissues. These data present evidence for the presence of detectable levels of NAD(P)H fluorescence in human epithelial tissues in an in vivo setting and demonstrate that NAD(P)H and collagen may be used as quantitative fluorescence biomarkers for in vivo detection of dysplasia in the cervix and the esophagus.

Barrett Esophagus↗

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.

Anal Canal↗

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.

Animals↗

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.

Adult↗

Trimodal spectroscopy for the detection and characterization of cervical precancers in vivo.

OBJECTIVE: The objective of this study was to assess the potential of 3 spectroscopic techniques (intrinsic fluorescence, diffuse reflectance, and light scattering) individually and in combination (trimodal spectroscopy) for the detection of cervical squamous intraepithelial lesions. STUDY DESIGN: The study was conducted with 44 patients who underwent colposcopy for the evaluation of an abnormal Papanicolaou smear. Fluorescence and reflectance spectra were collected from colposcopically normal and abnormal sites and analyzed to extract quantitative information about tissue biochemistry and morphologic condition. This information was compared with histopathologic classification, and diagnostic algorithms were developed and validated with the use of logistic regression and cross-validation. RESULTS: Diagnostically significant differences exist in the composition of fluorescing biochemicals, the scattering properties, and the epithelial cell nuclear morphology of cervical squamous intraepithelial lesions and non-squamous intraepithelial lesions. Trimodal spectroscopy is a superior tool for the detection of cervical squamous intraepithelial lesions than any 1 of the techniques alone. CONCLUSION: Trimodal spectroscopy has the potential to improve the in vivo detection of precancerous cervical changes.

Diagnosis, Differential↗

Managing atypical squamous cells of undetermined significance (ASCUS): human papillomavirus testing, ASCUS subtyping,or follow-up cytology?

OBJECTIVE: This study related morphologic subtype, human papillomavirus status, and a second cytologic examination to the follow-up biopsy-proven high-grade squamous intraepithelial lesion (HSIL; grade II or III cervical intraepithelial neoplasia) after a cytologic diagnosis of atypical squamous cells of undetermined significance (ASCUS). STUDY DESIGN: Seven hundred four liquid-based cervical cytology specimens were classified as normal, "ASCUS, favor reactive" (AFR), "ASCUS, not otherwise specified," "ASCUS, favor low-grade squamous intraepithelial lesion," "ASCUS, favor HSIL" (AFHS), low-grade squamous intraepithelial lesion, and HSIL. Human papillomavirus typing used polymerase chain reaction-restriction fragment length polymorphism analysis. A longitudinal review of the cytologic and histologic records of ASCUS cases with > or =1 follow-up test or biopsy ascertained the frequency of a follow-up diagnosis of biopsy-proven HSIL (grade II or III cervical intraepithelial neoplasia). RESULTS: Three hundred eighty-six cases (208 ASCUS, 68 normal, 86 with low-grade squamous intraepithelial lesions, and 24 with HSIL) were evaluated. High-risk human papillomavirus (HRHPV positive) was lowest with normal cytology (13%), highest with HSIL (71%), and was present in 29.8% of ASCUS cases, ranging from 22.2% (AFR) to 75% (AFHS). Most ASCUS tests (64%) were followed by a negative cytologic or histologic examination. Overall, 3.8% and 11% of ASCUS and HRHPV-positive ASCUS had histologic outcomes of HSIL. AFHS had the highest (25%) and AFR had the lowest (1.1%) proportion of HSIL outcomes. Sensitivity, specificity, and positive predictive values of human papillomavirus testing for biopsy-proven HSIL were 87.5%, 72.5%, and 11.3%, respectively. CONCLUSION: HSIL and AFHS are distinguished by the highest frequency of HRHPV types and higher rates of HSIL outcome. The remaining categories of ASCUS are heterogeneous with respect to human papillomavirus type and HSIL risk, and the value of subclassification of these entities is dependent on the practice. A human papillomavirus detection system based on polymerase chain reaction-restriction fragment length polymorphism identifies a smaller percentage of high-risk human papillomaviruses than mixed probe-based methods, probably because of the more precise exclusion of cross-reacting low-risk human papillomavirus. Negative HRHPV findings by either system show a markedly reduced risk of an HSIL outcome. However, the relative advantage of human papillomavirus testing over follow-up cytology will be influenced by the frequency of negative follow-up cytologic examination and sensitivity of liquid-based preparations in a given practice.

Adult↗

Human papillomaviruses. Applications, caveats and prevention.

Unlike cervical cytology, human papillomavirus (HPV) testing provides an objective assessment of neoplasia risk. The major advantages of this technology are the potential for "reflex testing" (when used with liquid-based cytology); efficient exclusion of HPV-negative women, who can be triaged to yearly follow-up; and identification of HPV-positive women, who require colposcopic triage. However, practitioners should be aware that highly sensitive HPV tests will also identify many women with little or no immediate risk of significant neoplasia, may impose a psychosocial burden on the patient and may be used or interpreted inappropriately by both practitioners and patients. However, these caveats are similar to those inherent in any screening program involving a sexually transmitted disease, and the disadvantages of HPV testing will be minimized by attention to patient concerns and a keen awareness of the limitations of this technology. Ultimately, control of cervical cancer and its precursors rests with active prevention via vaccination programs targeting HPV. If successful, such programs could radically alter the number of women requiring triage for preinvasive disease and initiate a progressive decline in cervical cancer incidence.

Colposcopy↗