Intermediate-effect biomarkers in prevention of skin cancer.

Skin cancers, both non-melanoma and melanoma, usually progress through sequential steps towards malignant transformation, leading to mutant clones and precancerous lesions. Prevention of skin cancers relies on reduction of exposure to solar radiation and may be evaluated by measuring induction of intermediate-effect biomarkers such as sunburn cells or p53 mutations in the epidermis, actinic (solar) keratoses, UV-induced immunosuppression or naevi. Sunburn cells (apoptotic keratinocytes) and p53 mutations are indicators of UV-induced DNA lesions as early steps of malignant transformation of epidermal keratinocytes. Actinic keratoses are premalignant sun-induced skin lesions, characterized as keratinized patches with aberrant cell differentiation and proliferation; they represent risk factors for basal-cell carcinoma and melanoma and are precursors of squamous-cell carcinoma. Studies in humans have investigated UV-induced immunosuppression and its modulation by topical sunscreen application, focusing on contact hypersensitivity as measured by immunization or response to haptens, or on modulation of stimulation of allogeneic lymphocytes by epidermal cells, or local release of immunomodulatory molecules such as cis-urocanic acid or interleukin-10. Naevi are focal collections of melanocytes, usually found at the junction of the epidermis and dermis or at various depths in the dermis. Common acquired naevi arise after birth both spontaneously and in response to sun exposure. Most acquired naevi are clonal, while most melanocytes in non-naeval areas are not. Although it is not yet certain whether naevi represent premalignant lesions or risk factors, many melanomas arise in acquired naevi, and the number of naevi constitutes the best predictor of individual risk of melanoma. The presence of large (i.e., >5 mm) or atypical naevi (i.e., large naevi with non-uniform colour and irregular borders) is associated with elevated melanoma risk, independently of the number of smaller naevi. Children seem particularly vulnerable to sun-induced biological events involved in the genesis of melanoma, and the greatest increase in naevus numbers per unit of skin surface occurs before adolescence. Therefore, the distribution of naevi and their development in children are relevant to understanding melanoma occurrence in adults.

The up-regulation of vascular endothelial growth factor in mutated Ha-ras HaCaT cell lines is reduced by a farnesyl transferase inhibitor.

The induction of tumor angiogenesis is mediated in particular by an increased production of VEGF. As ras oncogene is implicated in tumorigenesis, the inhibition of farnesyl transferase activity has recently been developed. The purpose of this study was to evaluate whether expression of mutated Ha-ras oncogene is associated with an altered expression of VEGF in an in vitro model of human skin carcinogenesis and to appreciate the effect of a new farnesyl transferase inhibitor on this VEGF expression. The amounts of VEGF secreted by an HaCaT cell line and two cell clones (metastatic or not) obtained after mutated c-Ha-ras transfection were compared. Our findings showed that the release of VEGF is greater for HaCaT-ras than for HaCaT cells and could be down-regulated using a protein farnesyl transferase inhibitor, in a reversible and dose-dependent manner. These results confirm that the Ha-ras oncogene can contribute to tumor development and progression of epidermal tumors through neoangiogenesis and that farnesyl transferase inhibitors as anticancer drugs may be efficient for the reduction of skin tumor growth.

Ras-transfection up-regulated HaCaT cell migration: inhibition by Marimastat.

Cell migration is an essential process in physiological and pathological conditions such as wound healing and tumor invasion. This phenomenon involves cell adhesion on the extracellular matrix mediated by integrins, and cell detachment promoted in part by metalloproteinases (MMPs). In the present study, the migration of two HaCaT-ras clones (metastatic or not), was compared with HaCaT cells, and normal human primary cultured keratinocytes. Using colloidal gold migration assay, the migration index on type I and type IV collagen was similar for primary cultured keratinocytes and HaCaT, whereas it was markedly higher for the HaCaT-ras clones. High motility of ras-transfected cells was confirmed from an in vitro wound healing assay. It was not correlated with changes in integrin expression or related to a different adhesion on extracellular matrix. The Marismastat (BB-2516), a MMP inhibitor, inhibited in a dose-dependent effect the migration in both assays, demonstrating the important role of MMPs in the migration process. Under our experimental conditions, MMP-1 activity was not detected in HaCaT and MMP-9 activity was secreted by these cells only after their stimulation by EGF. Here, MMP-2 was the major gelatinolytic activity secreted by all the cells and its secretion was markedly higher for HaCaT-nis clones compared with HaCaT. In addition, Western blotting results confirmed a higher expression of MMP-2 associated with a lower expression of TIMP-2 in HaCaT-ras compared with HaCaT. These results suggest that Ha-ras oncogene could be a stimulating factor of migration and might modified the balance between MMP-2 and TIMP-2 in keratinocyte cell lines.

Cell migration and MMP-9 secretion are increased by epidermal growth factor in HaCaT-ras transfected cells.

Mutated RAS oncoproteins and epidermal growth factor (EGF) are thought to contribute to the proliferative, invasive and metastatic properties of transformed cells. In the present study, we investigated the role of EGF in two H-ras transfected clones and compared it to that in the parental cell line, HaCaT and primary cultured keratinocytes. Our findings show that the motility on type I collagen, measured by the migration index, was similar for both the HaCaT cell line and normal human keratinocytes, whereas it was higher for the HaCaT-ras clones. These results suggest an involvement of the ras oncogene in the stimulation of cell migration. EGF in cell pretreatment or during the migration assay also caused an increase in migration of all the cells, but preserved the difference between HaCaT and HaCaT-ras. However, no significant difference in EGF-R expression was detected between normal cultured keratinocytes, HaCaT and HaCaT-ras cell lines with or without EGF pretreatment. Moreover, when the cells were stimulated with EGF, the MMP-9 activity was greatly increased in a dose-dependent manner in all the cells, and EGF stimulation particularly highlights the increased amount of MMP-9 in HaCaT-ras cells compared to HaCaT cells. In conclusion, EGF is able to enhance motility and to up-regulate MMP-9 activity in all cells, but with a higher impact in HaCaT-ras cells without an overexpression of EGF-R. As EGF acts in synergy with the H-ras mutation, they could be implicated in the local invasion by the HaCaT-ras clones.

Detection of low copy numbers of HPV DNA by fluorescent in situ hybridization combined with confocal microscopy as an alternative to in situ polymerase chain reaction.

In genital lesions infected by human papillomavirus (HPV), histological criteria and HPV DNA typing are of prognostic value. Therefore, non-radioactive methods such as in situ hybridization are used extensively since they preserve the histological organization of the tissue, and allow the detection and characterization of HPV DNA. However, the sensitivity of these methods is often limited to detection of low copy numbers of HPV DNA in isolated cells or in tissue sections, and therefore alternative techniques have been explored. In the present study, 1-2 copies of HPV DNA were visualized in SiHa cells either by in situ amplification of nucleic acid sequences with the polymerase chain reaction (PCR) or by fluorescent in situ hybridization (FISH) associated with observation by laser scanning confocal microscopy (LSCM). The latter procedure was evaluated for use on histological tissue sections to identify low copy numbers of HPV DNA. Genital lesions which were negative by enzymatic in situ hybridization and FISH but histologically suspected of HPV infection were investigated, and intense signals were obtained both with in situ PCR and with the combined use of FISH and LSCM. Therefore, the combination of FISH with LSCM examination may be as valuable as in situ PCR to detect viral genes present in small amounts in isolated cells and in tissue sections.

Detection of human papillomavirus DNA in genital lesions by enzymatic in situ hybridization with Fast Red and laser scanning confocal microscopy.

Human papillomavirus (HPV) infection with potentially oncogenic types 16 or 18 is common in genital lesions especially in uterine carcinomas. In such lesions, in situ hybridization with non-radioactive probes is a powerful tool for the histopathologist to detect and type HPV DNA either on cell deposits or on tissue sections. The use of an immunohistochemical method involving alkaline phosphatase and Fast Red TR salt/naphthol AS-MX phosphate is proposed for use with conventional bright-field or fluorescence microscopy as well as by laser scanning confocal microscopy. The alkaline phosphatase-Fast Red reaction has the advantage of producing a red precipitate that permits the detection of in situ hybridization signals by bright-field microscopy, and of obtaining a strong red fluorescence characterized by a lack of bleaching when excited by a green light. Therefore, the alkaline phosphatase-Fast Red reaction is well adapted for observations by fluorescence and confocal microscopy, the latter method allowing the detection, in tissue sections of cervical intraepithelial lesions, of small punctate and large diffuse hybridization signals, considered as integrated and episomal states of HPV DNA respectively. The combination of in situ hybridization with the alkaline phosphatase-Fast Red reaction and confocal microscopy is particularly convincing when hybridization signals are of small size and/or of low fluorescence intensity, especially if they are present in various focal planes; in such conditions, infected cells are easily detected by three-dimensional reconstruction. Therefore, this combination is a suitable method for identifying and characterizing HPV DNA in cells and tissue sections.

Differences of reactivity to interferon gamma in HeLa and CaSki cells: a combined immunocytochemical and flow-cytometric study.

We characterized the changes induced by treatment for 48 h with 100 U/ ml interferon gamma (IFN-gamma) on HeLa and CaSki cells, derived from human uterine carcinomas and containing human papillomavirus (HPV) type 16 and HPV type 18 respectively, by studying cell growth, cell morphology, the cell cycle and expression of epidermal growth factor (EGF) receptor, filaggrin-profilaggrin and MHC class II antigen, HLA-DR. The response of the two cell lines to IFN gamma differed in some cases. In both cell lines, the cells remained viable; cell growth was similarly inhibited as shown by cell counts. Signs of morphological changes were essentially observed in HeLa cells. The cell cycle phases, analyzed by flow cytometry were more disturbed in CaSki than in HeLa cells; the proportion of CaSki cells in S phase increased and those in G2 + M decreased. Expression of EGF receptors related to proliferation increased only in CaSki cells while expression of filaggrin-profilaggrin, a marker of differentiation, and HLA-DR, a marker of epithelial cell immune response, was enhanced in both cell lines. The presence of filaggrin-profilaggrin being unexpected in these cells, the specificity of the reaction with the monoclonal antibody AKH1 was confirmed by immunoblotting. In conclusion, our results show that the two cell lines reacted differently to IFN gamma although they are of similar origin and the different antigens studied may be useful to predict the progression of lesions infected with HPV towards malignancy or the reactivity to IFN gamma of such lesions. However, enhanced synthesis of EGF receptors is probably independent of the antiproliferative effect of IFN gamma but an increase in HLA-DR antigen expression by epithelial cells, which corresponds to an immune response favored by IFN gamma, could act synergistically with cell growth inhibition and differentiation to exclude tumoral and/or HPV-infected cells.

Differences in reactivity to cyclosporin A and interferon-gamma of normal and HPV-transformed keratinocytes.

In humans, cyclosporin A (CsA) avoids organ allograft rejection but induces skin carcinomas after long term immunosuppressive treatment; some of these lesions contain human papillomavirus (HPV) DNA. Interferon-gamma (IFN-gamma) is sometimes used in local treatment of persistent or recurrent lesions in normal population. In vivo, both drugs have an effect on keratinocytes which remains unclear. Therefore, their effect was studied on in vitro models of normal or HPV-transformed epithelial cell cultures. After exposure of proliferating cells for 1-3 days to 0.5-16 micrograms/ml CsA and 5-160 U/ml IFN-gamma, no cytotoxicity was observed; cell growth was inhibited; cell morphology was altered with CsA and cytoplasmic vacuoles were seen in some cells. Changes in the cell cycle were mainly obtained after treatment with 8 micrograms/ml CsA or 160 U/ml IFN-gamma, with an accumulation in S-phase especially in HPV-transformed cells. Thus, CsA and IFN-gamma affected, normal and HPV-transformed epithelial cells, differently.

Analytical methods for evaluation on whole cells of human papillomavirus infection.

Analytical methods for evaluation on whole cells of human papillomavirus infection. Human papillomavirus (HPV) infection is currently identified by the presence of viral DNA using molecular biology. As in situ hybridization is valuable for HPV-DNA detection mainly with non-isotopic probes, we evaluated the sensitivity of various techniques, using as models three cell lines containing different copy numbers of HPV DNA/cell (CaSki with 600 copies of HPV 16, SiHa with 1-2 copies of HPV 16, HeLa with 10-50 copies of HPV 18). Epifluorescence microscopy and flow cytometry allowed detection of 600 copies in CaSki cells; in addition, cell fixation was found to influence the fluorescent intensity. Several procedures were assayed to increase the sensitivity of in situ hybridization. The use of biotinylated HPV-16 oligonucleotides as probes was not effective, because only CaSki cells were positive. After amplification of HPV-16 or -18 DNA sequences with polymerase chain reaction (PCR) on whole cells in suspension and hybridization with plasmid probes, fluorescent hybridization spots were found in CaSki and HeLa cells by both epifluorescence microscopy and flow cytometry. The various procedures applied for revelation of DNA-DNA hybrids (use of phycoerythrin or cyanine instead of fluorescein, Pinkel's 3-step amplified system of fluorescein) did not enhance the sensitivity of in situ hybridization. HPV DNA was very effectively detected by cell examination under a laser-scanning confocal microscope, since 1-2 copies of HPV 16 were observed in SiHa cells without previous PCR amplification. Thus, the efficacy of in situ hybridization for HPV detection may be conditioned by different factors. Laser-scanning microscopy represents an alternative to the use of PCR amplification. These techniques are potentially useful to study single genes.

Active cell membrane mechanisms involved in the exclusion of Rh 123 allow distinction between normal and tumoral cells.

Human cell lines derived from three epithelial carcinomas (CaSki, HeLa, SiHa), one B lymphoma (BL60), one promyelocytic (HL60), one monocytic (U937) leukemia, one chronic myelogenous leukemia (sensitive K562S; multichemoresistant K562R) and normal human skin fibroblasts were compared for their capacity of staining with rhodamine 123 (Rh 123) and their kinetics of dye exclusion. Cells were exposed for 30 min to 10 micrograms/ml of Rh 123 in culture medium; fluorescence intensity was measured by flow cytometry immediately or 1, 2, 3 and 4 h after staining. The highest fluorescence intensity was observed in carcinoma cell lines; there was no incorporation in multichemoresistant K562R cells. Exclusion of Rh 123 was evaluated from 0 to 4 h, both by flow cytometry and by fluorimetry. Fluorescence intensity measured by flow cytometry decreased slightly in carcinoma and leukemia cells and rapidly in fibroblasts. In all cell lines Rh 123 exclusion was inhibited by 40 mumol/L verapamil and 5 mmol/L probenecid. Thus, incorporation and exclusion of Rh 123 allows distinction between normal and tumoral cells; moreover, inhibition of exclusion by verapamil and probenecid favors the involvement of active cell membrane mechanisms in the exclusion process.

[Detection of human papillomavirus DNA by in situ hybridization and gene amplification]. / Détection d'ADN de papillomavirus humains par hybridation et amplification génique in situ.

In situ hybridization with non radioactive probes is attractive for human papillomaviruses (HPV) detection. Its sensitivity has been greatly improved by using different hybridization conditions, techniques for revealing the DNA-DNA hybrids and method of observation and various cell lines derived from human uterine carcinomas (CaSki, SiHa and HeLa cells) which contain 500-600 copies of HPV DNA, 1-2 copies of HPV 16 and 20-50 copies of HPV DNA 18, respectively. In situ gene amplification increased the detection of HPV DNA since hybridization spots were visible in SiHa cells on slides; a specific signal was observed in HeLa cells in suspensions examined by flow cytometry. Confocal microscopy is an alternative method to in situ gene amplification since viral DNA is detectable in SiHa cells with or without gene amplification. Thus, the techniques used in this study are potentially useful for research of single cellular genes.

Improvements in visualisation and localisation of human papillomavirus DNA in CaSki cells by fluorescence in situ hybridization, laser scanning confocal microscopy and three-dimensional image reconstruction.

The visual interpretation and localisation of specific DNA sequences in three dimensions in cell nuclei was investigated by fluorescence in situ hybridization (FISH) and laser scanning confocal microscopy (LSCM) using CaSki cells containing 600 copies per cell of human papillomavirus (HPV) DNA type 16 integrated in cellular DNA. Biotinylated DNA probes were used and DNA-DNA hybrids were revealed by a three-step reaction involving a rabbit anti-biotin antibody, a biotinylated goat anti-rabbit antibody and a streptavidin-fluorescein isothiocyanate complex. The DNA from cell nuclei was counterstained with propidium iodide. With standard fluorescence microscopy, some dense fluorescent spots were seen in the cell nuclei. Similarly, with LSCM, some hybridization spots were observed in the cell nuclei but they were at different levels of the nuclei as shown by successive nuclear sections taken along the z axis. The visualisation of multiple hybridization spots confirmed the presence of multiple integration sites of HPV 16 DNA in CaSki cells. Association of LSCM with three-dimensional reconstructions lead to spatial images of hybridization spots obtained by stacking (x,y) images from consecutive confocal planes. Rotation of the reconstructed cell nuclei around the y axis makes it possible to distinguish closely adjacent spots. The combination of these techniques improves the detection of hybridization spots and may be of interest to further determine whether the HPV DNA is episomal or integrated in infected cells.

Laser scanning confocal microscopy and quantitative microscopy with a charge coupled device camera improve detection of human papillomavirus DNA revealed by fluorescence in situ hybridization.

Epithelial cervical CaSki, SiHa and HeLa cells containing respectively 600 copies of human papillomavirus (HPV) DNA type 16, 1-2 copies of HPV DNA type 16 and 10-50 copies of HPV DNA type 18 were used as model to detect different quantities of integrated HPV genome. The HPV DNA was identified on cell deposits with specific biotinylated DNA probes either by enzymatic in situ hybridization (EISH) or fluorescence in situ hybridization (FISH) involving successively a rabbit anti-biotin antibody, a biotinylated goat anti-rabbit antibody and streptavidin-alkaline phosphatase complex or streptavidin-fluorescein isothiocyanate complex. With brightfield microscopy and EISH, hybridization spots were observed in CaSki and HeLa cells but hardly any in SiHa cells. With fluorescence microscopy and FISH, hybridization spots were clearly seen only on CaSki cell nuclei. In an attempt to improve the detection of low quantities of HPV DNA signals revealed by FISH, laser scanning confocal microscopy (LSCM) and quantitative microscopy with an intensified charge coupled device (CCD) camera were used. With both LSCM and quantitative microscopy, as few as 1-2 copies of HPV DNA were detected and found to be confined to cell nuclei counterstained with propidium iodide. Under Nomarski phase contrast, a good preservation of the cell structure was observed. With quantitative microscopy, differences in the number, size, total area and integrated fluorescence intensity of hybridization spots per nucleus were revealed between CaSki, SiHa and HeLa cells.(ABSTRACT TRUNCATED AT 250 WORDS)

Heterogeneous immunoreactivity of frozen human benign and malignant breast lesions to C-MYC and C-Ha-ras cellular oncogenes.

C-myc and c-Ha-ras oncoprotein expression was studied by immunohistochemistry and gene detection by in situ hybridization on serial frozen sections of 32 breast lesions (19 benign biopsies and 13 infiltrating carcinomas). C-myc protein was expressed in 15/19 benign and 12/13 malignant lesions; c-myc gene was detected in 17/19 benign and 13/13 malignant lesions. Although a higher proportion of benign biopsies (8/9) showed more than 50% of protein-positive cells than malignant specimens, this cannot predict the outcome of a lesion. Conversely, p21 ras protein was expressed only in 2/19 benign lesions and in most cases of grade I to III carcinomas. The c-Ha-ras gene was always detected in a small percentage of cells, in both benign and malignant lesions. The results obtained with atypical hyperplasia, a doubtful proliferating lesion, suggests that p21 c-Ha-ras protein expression is not restricted to breast carcinomas. Although Southern blot is commonly considered as a very sensitive technique for oncogene analysis, no amplification of c-myc and c-Ha-ras gene has been demonstrated either in benign or malignant lesions. The detection, on serial frozen sections, of proteins and DNA of c-myc and c-Ha-ras, showed a possible amplification of the c-myc and c-Ha-ras genes in various benign and malignant lesions.

Association of skin malignancies with various and multiple carcinogenic and noncarcinogenic human papillomaviruses in renal transplant recipients.

BACKGROUND: Organ transplant recipients receiving immunosuppressive treatment are prone to skin carcinomas on sun-exposed areas, and the frequency of such carcinomas in the long term reaches 40%. These carcinomas primarily are squamous cell carcinomas (SCC), which often are preceded by viral warts and premalignant keratoses. Human papillomaviruses (HPV) with other cocarcinogenic factors have been reported to play a role in the development of carcinomas in these patients. METHODS: Five hundred renal-graft recipients referred to our department were examined for the presence of warts, precancerous keratoses, Bowen disease, keratoacanthomas, and basal and squamous cell carcinomas. Adequate material for histologic and virologic examination was obtained from 24 patients. An in situ molecular hybridization technique was performed using biotinylated DNA probes for HPV types 1a, 2a, 5, 16, and 18 under stringent conditions. RESULTS: HPV DNA was detected in 44 of 86 specimens, including 14 of 17 warts, 4 of 17 premalignant keratoses, 1 of 4 Bowen disease lesions, 8 of 12 keratoacanthomas, 3 of 4 tumors in which distinction between keratoacanthomas and SCC was difficult, and 14 of 30 SCC. Twenty-six of 44 positive specimens contained several HPV types, whereas 30 specimens contained oncogenic types. Benign types 1 or 2 were detected alone in five SCC. HPV types 16 and 18 (usually detected in genital lesions) were found in 26 samples from sun-exposed areas. CONCLUSIONS: Our results show that oncogenic and benign HPV often are detected within premalignant keratoses and SCC in organ transplant recipients, which suggests that HPV may play a role in the development of cutaneous malignancies.

Papilloma viruses, warts, carcinoma and Langerhans cells.

In human papillomavirus (HPV) infections, Langerhans cells (LC) are essential in the control of viral infection. The evolution of HPV-derived lesions in the normal population and in graft patients is drastically different, since a high proportion of papillomas progress towards malignancy in transplant recipients. We analyzed the distribution of markers of LC and T lymphocytes, the level of keratinocyte activation and the prevalence of HPV in a series of epithelial lesions obtained from the normal population and from graft patients. The local immune response of warts, condyloma acuminata, Bowen, basal and squamous cell carcinomas (SCC) showed a moderate to intense inflammatory reaction of HLA-DR positive cells, the intensity of the immune reaction being correlated with the degree of malignancy. In the normal population, CD4-positive cells were mainly overexpressed in the dermal infiltrate of condyloma and malignant lesions, whereas in grafted patients such infiltrates were CD4- and CD8-positive without significant predominance of a single T cell subset. The epidermis of most lesions was characterized by a reduced number of CD1a-positive LC with an altered morphology. This was concomitant with the decrease or loss of beta 2-microglobulin by epithelial cells. HLA-DR antigen was sometimes expressed by keratinocytes in genital lesions and SCC from the normal population but has not been detected in immunosuppressed patients. Whereas in the normal population HPV infection was only detected in benign papillomas, both benign and oncogenic HPV DNA may be present in carcinomas from graft patients.(ABSTRACT TRUNCATED AT 250 WORDS)

Detection of human papillomavirus DNA in CaSki and HeLa cells by fluorescent in situ hybridization. Analysis by flow cytometry and confocal laser scanning microscopy.

CaSki and HeLa cell lines, isolated from human uterine carcinomas and containing integrated human papillomavirus (HPV) DNA type 16 and 18, respectively were used to evaluate the sensitivity of HPV-DNA detection on suspended cells by fluorescent in situ hybridization using flow cytometry and on corresponding cell deposits using confocal laser scanning microscopy (CLSM). HPV DNAs were detected in cell suspensions with biotinylated DNA probes and revealed with a three-step technique: a rabbit antibiotin antibody, a biotinylated goat anti-rabbit antibody and a streptavidin-fluorescein isothiocyanate complex. By flow cytometry, HPV DNA was detectable only in CaSki cells which contained about 600 copies of HPV DNA per cell. In HeLa cells, with only 20-50 copies of HPV DNA, flow cytometry could not detect HPV DNA, whereas CLSM permitted visualization of fluorescent labelling of HPV DNA hybrids. Furthermore, CLSM showed good preservation of cellular morphology and the nucleus was clearly recognizable after fluorescent in situ hybridization and counterstaining with propidium iodide. Moreover, this examination confirmed that the fluorescent foci were specifically confined to the cell nuclei.

Influence of fixation on human papillomavirus DNA detection in frozen and embedded paraffin lesions by in situ hybridization with biotinylated probes.

Series of frozen or paraffin-embedded tissues from various body sites, taken from non-immunosuppressed or immunosuppressed patients with persistent papilloma lesions were examined for the presence of group specific antigen from human papillomavirus (HPV) by indirect immunofluorescence or HPV DNA by in situ hybridization with biotinylated probes. We have shown that it is possible to detect HPV DNA after fixation of tissues in neutral formalin, Bouin's or Baker's solution. However, the sensitivity was reduced as compared to frozen tissues. The HPV DNA was detected in nuclei of heavily infected epithelial cells such as plantar or hand warts or in dispersed cells containing high copy numbers of HPV DNA from lesions such as squamous cell carcinomas or keratoacanthomas. In premalignant or malignant lesions of both immunosuppressed or non-immunosuppressed patients, HPV DNA was rarely detected after fixation. HPV types commonly described for skin and genital samples were identified in non-immunosuppressed patients, whereas in transplant recipients oncogenic HPV type 16 was identified in benign warts as well as in premalignant or malignant lesions. Positive reactions with several HPV types were more frequent in lesions from grafted patients than from the normal population. Virus antigen was detectable more frequently in frozen sections than in fixed tissues. Our findings indicate that in situ hybridization is an appropriate and rapid technique to study the presence of HPV infection. However, numerous controls are needed to avoid misinterpretations.

Human papillomavirus DNA in cervix. In-situ hybridization with biotinylated probes on Bouin's fixed paraffin embedded specimens.

We examined retrospectively a series of 65 Bouin's fixed, paraffin-embedded tissue specimens from 8 condylomatous lesions, 16 condylomas associated with cervical intraepithelial neoplasia (CIN), and 12 neoplasia without condylomatous signs, for histological characteristics, the detection of viral structural antigen, the presence and typing of HPV DNA by molecular in situ hybridization with biotinylated probes types 6, 11, 16 and 18 under stringent conditions (Tm - 12 degrees C). HPV DNA was present in 34/65 (52%) specimens. Detection of viral structural antigen was positive in only 14% (3/22) specimens. HPV DNA were identified in 9/9 (100%) condylomatous lesions (with HPV type 6, 11, 18). Three condylomas were coinfected with both HPV type 6 or 11 and type 18; viral antigen was found in two specimens. HPV DNA were detected in 18/31 (58%) low grade and advanced CIN associated with condylomatous changes (type 6 = 5 specimens, type 11 = 3 specimens, type 16 = 4 specimens, type 18 = 6 specimens). Four of these cases were coinfected with both HPV type 6/11 and HPV type 16/18. Viral antigen was negative in all specimens. HPV DNA were detected in 7/25 (28%) advanced intra-cervical neoplasia (CIN III) without anatomopathological condylomatous changes (type 6 = 1 specimen, type 16 = 3 specimens, type 18 = 3 specimens). One of these specimens contained both HPV types 6 and 18. Viral antigen was found in one case. Our data confirm the association of HPV types 6 and 11 with condyloma and low grade neoplasia; HPV types 16 and 18 were associated with advanced cervical neoplasia.(ABSTRACT TRUNCATED AT 250 WORDS)