In situ viral DNA hybridization in diagnostic surgical pathology

Demonstration of cytoplasmic tyrosinase mRNA in tissue-cultured cells by reverse transcription (RT) in situ polymerase chain reaction (PCR) and RT PCR in situ hybridization

To evaluate the specificity and applicability to the study of human tumor cells of the reverse transcription (RT) in situ PCR and RT polymerase chain reaction (PCR) in situ hybridization techniques, we examined five melanoma cell lines and five nonmelanoma lines for tyrosinase mRNA using primers specific for tyrosinase. Each procedural step was optimized and minutely controlled, and results from the in situ techniques and solution-phase RT-PCR were compared. All melanoma lines showed a specific pattern of perinuclear cytoplasmic reaction not seen in nonmelanoma lines. There was exact agreement between the results from the RT in situ PCR and RT-PCR in situ hybridization techniques and those from solution-phase RT-PCR. Ribonuclease digestion abolished cytoplasmic staining, as did omission of the reverse transcriptase step. Nuclear staining was seen in melanoma and nonmelanoma lines, apparently as a result of DNA synthesis from repair-replication and mispriming or nonspecific amplification. Neither high concentrations of deoxyribonuclease nor long incubation periods abolished this effect completely. Demonstration of cytoplasmic mRNA by RT in situ PCR and RT-PCR in situ hybridization specifically identifies cells of melanocytic lineage.

Criteria for consistent and high sensitivity of DNA in situ hybridization on paraffin sections: optimal proteolytic enzyme digestion

It is technically challenging for the detection of target DNA in low abundancy, such as viral DNA sequences in latently infected cells by nonisotopic in situ hybridization (ISH). Consistent result is even more difficult to achieve on routine paraffin sections. Proteolytic enzyme digestion is most critical for both consistency and sensitivity of the technique. We here have investigated the effect of enzyme digestion on cell morphology, protein and DNA reduction, and hybridization efficiency. The results demonstrated that enzyme digestion improves efficiency of ISH through a process involving partial DNA purification on sections. There is a clear relationship between proteolytic enzyme digestion, morphology changes, and hybridization efficiency. Although detection of DNA sequences in abundance can be achieved within a relatively wide range of digestion levels, maximum hybridization efficiency was always related to the cells, which showed morphology of nuclear swollen, weak homogeneous chromatin staining with hematoxylin and loss of visible nuclear membrane. Detection of viral DNA in low copy number critically depends on the creation of the morphologic changes by enzyme digestion. The morphological changes would therefore serve as important criteria for optimal digestion, result interpretation, and comparison.

Chronic encephalitis and epilepsy (Rasmussen's encephalitis): detection of cytomegalovirus and herpes simplex virus 1 by the polymerase chain reaction and in situ hybridization

We made a pathologic diagnosis of chronic encephalitis on surgical resections or autopsy material in 10 patients with intractable seizures and studied the specimens by immunohistochemistry for herpes simplex virus (HSV) 1 and 2 and cytomegalovirus (CMV) as well as by the polymerase chain reaction (PCR) for viral DNA sequences (HSV1, HSV2, and CMV). We also assessed eight patients (nonepileptic) with pathologically documented or clinically suspected encephalitis and five resections from epileptics without encephalitis. Immunohistochemistry for viral antigens was negative in all cases. Using PCR assay, CMV was present in six and HSV1 in two of 10 epilepsy patients with chronic encephalitis. We demonstrated CMV by in situ hybridization in two of the six patients positive for CMV by PCR. We found no viral sequences by PCR in five epileptics without encephalitis. Of the eight patients (nonepileptic) with clinically suspected or pathologically confirmed encephalitis, two cases showed CMV sequences by PCR. These observations suggest that PCR allows detection of viral sequences in some cases of chronic encephalitis associated with epilepsy that may be missed by in situ hybridization.

Detection of human papillomavirus DNA in an ameloblastoma using the in situ hybridization technique

HPV type 18 DNA was identified in an intrabony ameloblastoma using radiolabelled in situ hybridization. The viral DNA was found in a verrucous lesion in a cystic area of the tumor. The absence of HPV DNA in other epithelial areas of the ameloblastoma is suggestive of a secondary infection. HPV is not considered to be an etiological factor in the pathogenesis of this ameloblastoma.

Alpha-1 antitrypsin gene exon use in stimulated lymphocytes

AIMS

To investigate the expression of mRNA transcripts containing exon A or B in lymphocyte cultures.

METHODS

An in situ hybridisation technique, using synthetic, biotinylated oligonucleotide probes was deployed to allow the demonstration of exon A, exon B, or the normal hepatocyte message containing exon C.

RESULTS

Lymphocytes used the same alternative splicing technique as monocytes in the generation of their alpha-1 antitrypsin message. They also provided data on the frequency of exon A and B expression in cells from different subjects. Most circulating granulocytes failed to show the alpha-1 antitrypsin message, suggesting that this protein is synthesised in the marrow and represents a stored protein component in polymorph and circulating nuclear lymphocytes.

CONCLUSIONS

In situ hybridisation is a sensitive technique for the detection of individual gene exon use in cell populations. Lymphocytes show the same promoter use as that described for monocytes.

In situ hybridization at light and electron microscopic levels: identification of human papillomavirus nucleic acids

A comparison of the sensitivities of biotinylated and 32P-labelled human papillomavirus type 6b DNA probes was made. Slot blot hybridization results showed that the sensitivity of biotinylated probes was consistent with that of 32P-labelled, that is, 0.1 pg of pBR 322 plasmid containing 8 kbp HPV cDNA. In situ hybridization using 35S-labelled probes was applied to tissue from condylomata acuminata. After autoradiography, many silver grains were seen concentrated over the superficial koilocytic nuclei with some grains present in the cytoplasm. Biotinylated probes were visualized by 4 different means, i.e., streptavidin alkaline phosphatase, streptavidin biotinylated horseradish peroxidase, monoclonal anti-biotin antibody with 15 nm colloidal gold and streptavidin 5 nm colloidal gold. Strong reaction products were localized in the superficial nuclei while the cytoplasm of koilocytes showed weak hybridization signal. Pre-embedding methods were carried out for electron microscopic studies in which numerous granular diaminobenzidine (DAB) products were present in the nuclear chromatin while viral particles themselves had much fewer DAB products. This suggested that hybridization occurred more efficiently to yet unassembled viral genomes than to matured virions. Post-embedding methods using 15 nm colloidal gold were performed and showed singly scattered or clustered gold particles in superficial koilocytic nuclei.

The prevalence of human papillomavirus in cervical lesions with koilocytosis and/or CIN I

Thirty-one patients with koilocytosis and/or concomitant CIN I were analysed for the presence of HPV types 11, 16 and 18 by in situ hybridization and Southern blot analysis. The prevalence of HPV was 48% and 55%, respectively, when measured by the two methods and among the HPV positive, HPV 11 and 16 were present in 47% and 60%, respectively, whereas HPV 18 was not found.

Neuropathologic findings in cortical resections (including hemispherectomies) performed for the treatment of intractable childhood epilepsy

Despite the use of hemispherectomy in the treatment of medically refractory seizures since the early 1950's, few studies published have documented neuropathologic findings in the resected specimens. This report describes the neuropathologic findings in 38 children who underwent either hemispherectomy or multilobar cortical resection as treatment for medically intractable epilepsy between 1986 and 1990. Examination of the resected specimens revealed a variety of abnormalities which fell into four broad categories. Malformations or hamartomatous lesions were the dominant finding in 15 patients, whereas encephalomalacic lesions were the most prominent abnormality in 16; chronic pathogen-free encephalitits (Rasmussen's encephalitis) was present in 3 and an additional 3 children had Sturge-Weber-Dimitri syndrome. There were no gross or microscopic abnormalities in 1 patient. This report provides the first comprehensive description of the pathologic findings in a series of children with refractory epilepsy of varying types treated by hemispherectomy-multilobar resection.

In situ hybridisation of albumin mRNA in normal liver and hepatocellular carcinoma with a digoxigenin labelled oligonucleotide probe

AIMS

To study the localisation and distribution of albumin mRNA in normal liver and hepatocellular carcinoma by in situ hybridisation with an oligonucleotide probe.

METHODS

A 51 base oligonucleotide was synthesised from a sequence at the 5' end of the human albumin gene and the probe was labelled at its 3' end with digoxigenin 11-dUTP. Formalin fixed, wax embedded sections of liver biopsy specimens were used to study the localisation and distribution of albumin mRNA. After in situ hybridisation the bound probe was visualised using a digoxigenin antibody conjugated with alkaline phosphatase.

RESULTS

In normal liver albumin mRNA was detected in hepatocytes and no positive signal was observed in biliary epithelium, vascular endothelium, or Kupffer cells. In 75% (9/12) of the hepatocellular carcinomas studied a positive hybridisation signal was observed in tumour cells.

CONCLUSIONS

Albumin mRNA can be detected in sections of formalin fixed, wax embedded liver, a digoxigenin labelled probe is ideally suited for in situ hybridisation of liver because there is no background from the detection system. The identification of albumin mRNA may be a useful marker of hepatocellular carcinoma, and the demonstration of albumin mRNA by in situ hybridisation overcomes the potential background problem associated with albumin immunohistochemistry.

Rapid detection of gene expression

Conventional methods of in situ hybridization are not only complex, laborious and lengthy, tending to produce poor cellular resolution but are also inherently hazardous. We report a new method that overcomes many of these difficulties. Denovo attachment of a non-isotopic ligand, viz. 5-bromo-2'-deoxyuridine (BrdU) to oligonucleotide probes guaranteed the production of labelled probes of 100% specific activity that gave consistent, reproducible results, within hours, in a rapid in situ hybridization (ISH) technique. The method is demonstrated by localization of insulin-like growth factor II (IGF-II) mRNA in human intracranial tumours and foetal brain. Five of 10 meningiomas expressed IGF-II mRNA to an extent of 1% of their tumour cells and two of three pituitary adenomas exhibited a less than 0.2% IGF-II mRNA-positive cell population. IGF-II may be important in the progression and/or maintenance of these tumours. Foetal brain showed no hybridization. The method's simplicity, rapidity and reliability commends its use in a variety of research and diagnostic applications and the BrdU-labelled probes can be used in any hybridization technique.

Detection of human papillomavirus DNA in cancer of the urinary bladder by in situ hybridisation

The association of the human papillomavirus (HPV) with cancer of the urinary bladder was assessed by in situ hybridisation using probes selective for HPV types 6/11 and 16/18 DNA. No hybridisation signal was detected with the type 6/11 probe on 100 formalin-fixed, paraffin-embedded bladder tumours sampled. However, when the same samples were hybridised with the HPV type 16/18 DNA probe, 11 of 66 (16.6%) papillary and 1 of 10 (10%) solid transitional cell carcinomas gave positive signals. These results suggest the involvement of HPV in cancer of the bladder, although the frequency of multiple HPV types in these tumours is uncertain.

Collagen mRNA expression detected by in situ hybridization in keloid tissue

The keloid fibroblasts exhibited increased extracellular matrix gene expression, and prominent elevated type I procollagen mRNA when compared to control fibroblasts cultured from the uninvolved skin of normal people. It also showed markedly elevated type I/III procollagen mRNA ratios, but no synthesis of type IV procollagen mRNA by keloid fibroblasts was observed. By in situ hybridization in keloid tissue, high levels of type I and type III procollagen mRNAs were detected in most of the fibroblasts, suggesting the presence of a subpopulation responsible for the increased collagen production. The levels of type I and type III procollagen mRNAs in these fibroblasts were clearly elevated compared to control skin specimens. And concentration of type I procollagen mRNA was found more predominantly than was type III. These results suggest that deposition of collagen in keloid could result from activation of certain fibroblasts responsible for type I procollagen production.

Comparative in situ hybridisation study of juvenile laryngeal papillomatosis in Papua New Guinea and Australia

A comparative study of cases of juvenile laryngeal papillomatosis from Papua New Guinea (n = 3) and Brisbane, Australia (n = 9) was carried out. In situ hybridisation reactions for human papillomavirus (HPV) types 6 and 11 occurred in 11 cases. All three cases from Papua New Guinea and eight from Australia gave positive signals. A negative reaction was observed in one Australian case. The intensity of the reaction was strong in seven cases, moderate in one, and weak in three. An equivocal reaction was also noted with probes for types 16 and 18, and types 31, 33, and 35 in two cases from Australia and one from Papua New Guinea. It is concluded that as similar staining patterns and intensities occurred in cases from both areas, the aetiology is the same. The equivocal reactions noted in three cases were probably due to cross hybridisation rather than multiple infection.

The future anatomic pathology laboratory for molecular diagnosis and prognosis: circa 1990-95

Molecular biology provides analytical tools for the study of human disease. These clinical assays can help make a diagnosis, predict a prognosis, or elucidate the pathogenesis of poorly understood diseases. The detection and/or quantitation of specific genes, messenger RNA's, and their protein products provide diagnostic and prognostic information for physicians. Illustrative applications of some of these techniques in human virus infection and breast cancer will suggest the future direction that an anatomic pathology laboratory should consider if it is to provide optimal and competitive service to physicians.

Infection of the heart by the human immunodeficiency virus

Heart muscle disease in the acquired immune deficiency syndrome (AIDS), characterized by electrocardiographic changes or congestive cardiomyopathy, is a documented clinical problem, but its pathogenesis is obscure. In AIDS the heart is known to be involved by a variety of opportunistic infections as well as Kaposi's sarcoma, but no causative relation with the development of cardiomyopathy has been established. This study reports evidence for direct infection of the heart in AIDS, not by an opportunistic pathogen but by the AIDS, not by an opportunistic pathogen but by the AIDS virus itself, the human immunodeficiency virus (HIV). For this study the technique of in situ deoxyribonucleic acid hybridization was applied to cardiac tissues obtained at autopsy from AIDS patients. Using sulfur-35-labeled ribonucleic acid probes encompassing the entire HIV genome, HIV nucleic acid sequences were detected in cardiac tissue sections from 6 of 22 patients examined who died of AIDS. The hybridization targets appeared to be cardiac myocytes, although their precise morphology was often obscured by the intensity of the signal. The myocardial cells showing a positive hybridization signal were sparse, often comprising only 1 or a few cells per section, and their number and location did not correlate obviously with any histopathologic or clinical evidence of heart muscle disease in these patients. It is conceivable that the presence of HIV nucleic acid sequences may represent a preclinical marker of impending AIDS-associated heart muscle disease. This sequela would not be recognized in many patients, including those in this series, who died rapidly of Pneumocystis carinii pneumonia, Kaposi's sarcoma and other well-documented manifestations of AIDS.(ABSTRACT TRUNCATED AT 250 WORDS)

Cytomegalovirus and human herpesvirus-6 in sudden infant death syndrome: an in situ hybridization study

Thirty lung, spleen, and thymus sections and four lymph node sections from 40 sudden infant death syndrome (SIDS) cases were probed with biotinylated DNA probes specific for human herpesvirus-6 (HHV-6) and cytomegalovirus (CMV). Control material gave a strong, distinct signal with little or no background staining and no cross-reactivity. No staining was found with the SIDS material. We find no evidence to implicate an overwhelming infection by either virus in SIDS.

The role of tumor markers in the early detection of cancer

Tumor markers include a broad range of substances expressed at different levels and in different biochemical forms. Bence-Jones protein, carcino-embryonic antigen and alpha-fetoprotein are recognized as some of the earlier utilized markers. Recent technologic advances have led to the development of a variety of serum tumor markers, tumor markers in body fluids, tissue tumor markers, and genetic tumor markers, such as protooncogenes.

Colorimetric in-situ hybridization in clinical virology: development of automated technology

Automation of in situ hybridization is an important first step toward practical implementation of the widely recognized diagnostic potential of nucleic acid hybridization. Our laboratory has concentrated its efforts towards automating colorimetric in situ hybridization on formalin-fixed paraffin-embedded tissue sections. We have capitalized upon the technology developed for the automation of immunohistochemistry (Brigati et al. 1988) and are collaborating with Fisher Scientific in modifying the Fisher Code-On Stainer to achieve successful automated in situ hybridization. Preliminary results are encouraging. We feel that the capillary gap technology has the potential to be modified to automate other hybridization assay formats such as dot and sandwich blot hybridizations. While specifically developed for colorimetric hybridization, the instrumentation is self-contained and could be safely adapted to the use of radio-labeled probes if necessary.

Sensitivity of in situ hybridization techniques using biotin- and 35S-labeled human papillomavirus (HPV) DNA probes

In order to evaluate the sensitivity of our modified in situ DNA hybridization technique using biotinylated probes, formalin fixed, paraffin embedded biopsies from 20 cervical lesions known to contain human papillomavirus (HPV) DNA were re-examined by the technique using both 35S-labeled- and biotinylated HPV DNA probes. The probe concentrations as well as the detection limits of biotin probing were screened by spotting known amounts of HPV 16 DNA on nylon filter, and allowed to hybridize with biotinylated HPV 16 DNA probe. By this method, 4 pg of HPV 16 DNA could be detected using a probe concentration of 0.2 micrograms/ml. HPV DNA could be demonstrated in all 20 biopsies with both hybridization techniques. However, signals in subrabasal cells were detected more frequently with biotin- than with 35S-labeled probes. Additional experiments were performed using three cervical cancer cell lines (with known copy numbers of HPV DNA), to assess the detection limits of HPV infections by the in situ hybridization techniques. The CaSki cells (500-600 HPV 16 copies/cell) were unequivocally positive with both labelling systems. HeLa cells (10-50 HPV 18 copies/cell) were positive with the biotin probing in 10/10 smears, as compared to 7/10 smears when 35S-labeled probes were used. Radioactive probing was inferior to biotinylated probing in detecting the signals in SiHa cells (1-2 HPV 16 copies/cell). This is because even weak background signals could mask true positive signals when 35S-labeled probes are used. In contrast, no background is generated with the biotinylated probes, detected with streptavidin-biotinylated alkaline phosphatase complex. In situ hybridization with biotinylated DNA probes is as sensitive as techniques using 35S-labeled probes for detecting HPV infections in routine cervical biopsies or smears.

Use of molecular probes in the study of endocrine diseases

DNA hybridization techniques are now commonly used in studies of endocrine disease. Although solution and filter hybridization have been more widely used in endocrine studies, ISH offers many advantages to the pathologist. Individual cells can be visualized directly with the microscope to study the expression of specific gene products. ISH is somewhat similar to immunohistochemistry and can be set up rapidly in most histology laboratories, especially when nonradioactive biotinylated probes are used. The ability to combine ISH with immunochemical techniques offers to the pathologist the use of two powerful diagnostic tools simultaneously. Although DNA hybridization has only begun to have an impact in diagnostic pathology, many studies using this technique in the diagnosis of endocrine diseases are emerging. The availability of more probes, especially with nonradioactive detection systems, should accelerate the application of these techniques in diagnostic pathology. As the number of molecular probes available for hybridization studies increases, pathologists can have a major impact in this field by carefully evaluating probes that have potential diagnostic value for their specificity and sensitivity in a wide variety of normal and abnormal human tissues. Such careful and critical analyses will contribute greatly to the confidence with which these molecular probes can be used as another tool in the analysis of difficult diagnostic lesions. Molecular hybridization techniques will also contribute greatly to our knowledge of basic biology and pathophysiology in the study of abnormal gene expression in endocrine and other pathologic conditions.