Flow cytometric quantitation of DNA and c-myc oncoprotein in archival biopsies of uterine cervix neoplasia

A multicolour flow cytometric assay for c-MYC protein in B-cell lymphoma

AIM

Develop an objective assay to detect c-MYC protein expression using multiparametric flow cytometry (FCM) as an alternative to immunohistochemistry (IHC).

METHODS

57 patient samples and 11 cell line samples were evaluated. Cell suspensions were obtained and c-MYC staining was performed in combination with CD45 and CD19 and, in some samples, CD10. The percentage of c-MYC+ cells by FCM was correlated with the percentage determined by IHC. The relationship between c-MYC protein expression and the presence of a c-MYC gene rearrangement in aggressive and high-grade lymphomas was also assessed.

RESULTS

c-MYC expression by FCM and IHC demonstrated a high degree of correlation in a training set of 33 patient cases, r=0.92, 11 cell line samples, r=0.81 and in a validation set of 24 aggressive and high-grade B-cell lymphomas, r=0.85. c-MYC gene was rearranged by fluorescence in situ hybridisation in 6/9 samples with high c-MYC expression (>40%) by FCM and 6/14 by IHC.

CONCLUSIONS

We have developed a reliable multicolour FCM assay to detect c-MYC expression suitable for clinical laboratories that should be helpful to accurately quantify c-MYC expression in B-cell lymphomas.

Ploidy and Proliferation Evaluated by Flow Cytometry. An Overview of Techniques and Impact in Oncology

Flow cytometric methods for the assessment of nuclear and chromosomal DNA content and of cell proliferation (including methods based on pulse-chase of bromodeoxyuridine and on monoclonal antibodies against nuclear oncoproteins and proliferation-associated antigens) are illustrated by examples and analyzed critically. The impact of most of these techniques for the study of human solid tumors, with exception of nuclear DNA content evaluation, appears still limited. In particular, new studies of cell lines and clinical material from human tumors using new proliferation markers and multiparameter flow cytometry are necessary to solve a considerable number of methodologic and scientific problems.

Multivariate analyses of DNA index, p62c-myc, and clinicopathological status of patients with ovarian cancer

AIM

To determine if either DNA index or p62c-myc is an independent prognostic variable in ovarian cancer.

METHODS

Multivariate and univariate analyses of the relation between DNA index, p62c-myc, FIGO stage, histological type, tumour grade, completeness of surgery, and patient survival in ovarian cancer were examined.

RESULTS

Multivariate analysis showed significant association of survival only with stage and grade. There was no relation between survival and DNA index.

CONCLUSIONS

DNA index is not an independent prognostic variable in ovarian cancer.

Structure, growth and cell proliferation of human osteosarcoma and malignant fibrous histiocytoma xenografts in serial transplantation in nude mice

Tumour specimens from one patient with osteosarcoma and one with malignant fibrous histiocytoma were transplanted in serial passages in nude mice. Structure, growth and cell kinetics of the xenografts were studied in order to assess the validity of the two tumour models. Cell proliferation was analysed using in vivo labelling with the thymidine analogue iododeoxyuridine (IdUrd) and the IdUrd labelling index (LI) was determined by immunohistochemistry. The DNA index (DI) was examined by flow cytometry. The c-myc oncoprotein expression was studied by immunohistochemistry. More intense proliferation was observed in the peripheral parts of the tumours. There was no correlation between tumour growth and cell proliferation in the two tumour groups. Stability of the tumour models was indicated by low intrapassage and interpassage variations of DI, LI, and volume doubling time, and also by retained histopathological characteristics and c-myc staining patterns of donor patients' tumours during serial transplantation.

Immunohistochemical detection of oncogene proteins and neuroendocrine differentiation in different stages of prostate cancer

The progression of prostatic adenocarcinoma from localized disease to metastatic carcinoma appears to be a multi-step sequence. The expression of common oncogenes/oncosuppressor genes and the mediating effect of neuroendocrine tumor cells may play a role in this progression. The expression of the more frequently investigated oncogenes/oncosuppressor genes (p53, c-myc, c-erbB-2, bcl-2) and the presence of neuroendocrine cells were assessed in prostatic cancer tissue from patients with localized and metastatic cancer. These oncogenes/oncosuppressor genes were evaluated according to tumor stage and grade and their relationship to one another. Grade was not related to any of the oncogene markers or to the presence of neuroendocrine cells. Advancing stage was associated with a significant increase in p53 expression, while other markers remained constant in all stages. Neuroendocrine cells, p53, c-myc, c-erbB-2 and bcl-2 were rarely co-expressed at any stage of prostate cancer.

Nuclear proto-oncogene products transactivate the human papillomavirus type 16 promoter

Human papillomavirus (HPV) type 16 and 18 viral genomes are frequently detected in cervical and penile cancer biopsies. Although this strongly suggests a prominent role for HPV infection in the development of genital cancer, other genetic or environmental factors are also involved. Genital cancer is postulated to result from loss of cellular control functions, which leads to an unregulated expression of HPV oncogenic proteins. In our study, we determined the trans-activating properties of nuclear proto-oncogene proteins c-Fos, c-Jun and c-Myc on P97 enhancer/promoter activity of HPV16. Using a CAT-reporter construct containing the HPV16 enhancer/promoter element, we investigated the trans-activating effects of c-Fos, c-Jun, c-Myc, and E2 in cervical HT-3 cells. c-Fos and c-Jun overexpression resulted in a 3.3- and 3.1-fold up-regulation of CAT activity. Only 2-fold induction was determined by co-transfection with c-myc and the viral transcription factor E2. Based on these findings, we investigated the expression of HPV DNA (16 and 18) as well as nuclear proto-oncogenes (c-fos, c-jun and c-myc) in nine cervical cancers by in situ hybridisation. In six out of nine carcinomas, HPV16 and/or HPV18 DNA was detectable. All tumours showed an intense and homogeneous expression of c-fos and c-jun mRNA, while the signal for c-myc was detectable only in four specimens. These data suggest that deregulation of nuclear proto-oncogene expression may contribute to an overexpression of HPV-derived oncogenic proteins (E6 and E7), which is generally hypothesised to be an important step in the malignant transformation of HPV-associated tumours.

Surrogate endpoint biomarkers for cervical cancer chemopreventive trials

Cervical intraepithelial neoplasia (CIN) represents a spectrum of epithelial changes that provide an excellent model for developing chemopreventive interventions for cervical cancer. Possible drug effect surrogate endpoint biomarkers are dependent on the agent under investigation. Published and preliminary clinical reports suggest retinoids and carotenoids are effective chemopreventive agents for CIN. Determination of plasma and tissue pharmacology of these agents and their metabolites could serve as drug effect intermediate endpoints. In addition, retinoic acid receptors could serve a both drug and biological effect intermediate endpoints. Possible biological effect surrogate endpoint biomarkers include cytomorphological parameters, proliferation markers, genomic markers, regulatory markers, and differentiation. Given the demonstrated causality of human papillomavirus (HPV) for cervical cancer, establishing the relationship to HPV will be an essential component of any biological intermediate endpoint biomarker. The pathologic effect surrogate endpoint biomarker for cervical cancer is CIN, used clinically for years. The desired effect for chemopreventive trials is complete regression or prevention progression. In planning chemoprevention trials, investigators need to consider spontaneous regression rates, the subjective nature of detecting CIN, and the impact of biopsy on regression. If intermediate endpoint biomarkers that met the above criteria were available for cervical cancer, then new chemopreventive agents could be rapidly explored. The efficacy of these new agents could be determined with a moderate number of subjects exposed to minimal risk over an acceptable amount of time. The impacts on health care for women would be significant.

Changes in oncogene expression in ascite tumour cells during ageing

The expression of two oncogenes, c-myc and c-fos, was studied in an ascitic tumour (ATPC+) at different times after implantation. The specific mRNA synthesis was analysed by Northern blot analysis. The presence of the oncogene proteins was shown by immunofluorescence using flow cytometry and referred to the distribution of the cells in the different cell phases. The results show that both oncogenes are expressed by ATPC+ tumour cells. c-myc is expressed 5, 8 and 12 days after implantation, although with a different intensity, and the protein is mainly present in S or S+G2 phase cells. The c-fos oncogene is expressed only 12 days after tumour implantation and the cells labelled with the specific antibody are mainly in G1 phase. We conclude that c-myc is principally correlated with proliferative activity, whereas c-fos is expressed by non-cycling cells.

Oncogene expression in cervical cancer

Significant advances have been made toward the understanding of the initiation and progression of cervical dysplasia and neoplasia at the molecular level. To date, this has not translated into improvements in diagnosis or treatment although it is a realistic expectation that this will occur. Significant variation in the proportion of tissue specimens that exhibit genetic alterations is striking. This may be attributed to different methods of analysis, different methods of tissue fixation, which influence antigen preservation, and the analysis of small numbers of samples per report, which introduces the possibility of sampling error. In spite of the variation among published reports, it is clear that several genetic alterations occur in preneoplastic and early-stage invasive cervical neoplasms. It remains to be determined which alterations of genetic structure or expression contribute to tumor initiation. The prognostic applicability of oncogene mutations is a particularly interesting area of investigation that is the closest to clinical application, although additional research involving larger numbers of patients is critical. The development of convenient methods of tissue fixation that preserve the myc oncoprotein, the synthesis of specific antibodies that provide consistent results, and the application of computer-assisted image analysis to quantitate results will be particularly important in this regard.

The control of chondrocyte differentiation during endochondral bone growth in vivo: changes in TGF-beta and the proto-oncogene c-myc

The expression of transforming growth factor-beta and the c-myc proto-oncogene was studied in situ in the chondrocytes of the tibial growth plate of normal chicks and those with avian tibial dyschondroplasia in which the chondrocytes are developmentally arrested in the transitional phase between proliferation and differentiation. This results in an accumulation of unmineralised and avascular cartilage. Dyschondroplastic chicks showed reduced c-myc expression in the transitional chondrocytes but unaltered levels in the proliferating chondrocytes. Transforming growth factor-beta expression was reduced in the transitional chondrocytes of dyschondroplastic chicks. In areas where the lesion was being repaired there was evidence of increased expression of both c-myc protein and transforming growth factor-beta. Addition of 1,25-dihydroxyvitamin D to the diet, which is known to reduce the incidence of dyschondroplasia, resulted in an increase in c-myc production. These results suggest that both transforming growth factor-beta and the proto-oncogene c-myc may be important elements of the cascade of events that lead to chondrocyte differentiation, hypertrophy and mineralisation.

Measurement of cell kinetics in cervical tumours using bromodeoxyuridine

The pre-treatment cell kinetics of 120 cervical tumours were assessed following the in vivo labelling with the thymidine analogue Bromodeoxyuridine (BrdUrd). In 89% both static and temporal kinetic parameters could be measured. Through the analysis of multiple biopsies from each tumour marked intra tumour heterogeneity was demonstrated. The median values for the most highly labelled sample analysed for each tumour were; S-phase duration (Ts) 12.1 h, BrdUrd labelling index (CLI) 9.5% and potential tumour doubling time 4.4 days. There was a significant elevation in CLI, but no difference in Ts, between tumour and non-neoplastic cervical tissue. There was a significant elevation in CLI, advanced stage and large size tumours. Although a significant elevation in CLI was found in aneuploid tumours this is likely to represent the systemic bias of the calculation methods, with no difference being seen between aneuploid and diploid tumours when BrdUrd labelling was measured with-out reference to the nuclei DNA content. The majority of these patients were treated with radiotherapy and cell kinetic data will be correlated with treatment response when adequate follow up has been achieved.

C-myc oncogene expression in anal squamous neoplasia

AIMS

To determine the pattern of c-myc oncogene expression in anal squamous neoplasia and to determine if this could be used as a marker of disease progression.

METHODS

The presence and localisation of the c-myc gene product p62 in archival specimens of anal squamous epithelium, normal and neoplastic, was examined using immunohistochemical staining with the monoclonal antibody Myc1-6E10. Ten normal and epithelia, 10 anal intraepithelial neoplasia (AIN) III, and 31 anal squamous cancers were examined.

RESULTS

There was a noticeable difference between the staining characteristics of invasive tumours, normal anal epithelium, and AIN III. Intense, diffuse, mixed nuclear and cytoplasmic (n = 14) and exclusively nuclear (n = 8) staining in 22 of 31 (71%) of invasive anal tumours was observed. All positively staining tumours were well differentiated histologically, while the negatively staining nine of 31 (29%) were poorly differentiated (n = 7) and moderately well differentiated (n = 2). In six positively staining tumour sections adjacent areas of AIN III and non-dysplastic anal epithelium had staining characteristics similar to those of the invasive component. Staining in both normal anal epithelium (4/10) and AIN III specimens obtained from patients without a history of invasive disease (8/10) was less intense, focal in distribution, and exclusively nuclear. No difference in staining characteristics could be detected in these two groups.

CONCLUSIONS

The results of this study suggest that c-myc oncogene expression is implicated in the pathogenesis of anal squamous neoplasia, and that immunohistochemical staining for c-myc protein may be helpful in identifying those AIN III lesions most likely to progress to invasive tumours.

The proto-oncogene c-myc is involved in cell differentiation as well as cell proliferation: studies on growth plate chondrocytes in situ

A combination of immunocytochemistry and microdensitometry has been used to localize and quantify the expression of the proto-oncogene c-myc within chondrocytes of the proximal growth plates of rat and chick long bones. Although the c-myc protein was localized in all chondrocytes of the growth plate of both species the most intense staining was restricted to the proliferating and differentiating chondrocytes. These were identified by their ability to synthesize DNA (bromodeoxyuridine positive) and the presence of alkaline phosphatase activity, respectively. Species differences did exist with the c-myc concentration of the chick proliferating and differentiating chondrocytes being higher (128% and 240%, respectively) than the respective chondrocytes of the rat. The higher c-myc concentration in the chick proliferating chondrocytes paralleled the differences in the bromodeoxyuridine labelling index between the two species. In the rat, the concentration of c-myc protein present in the differentiating chondrocytes was 74% higher than in the respective proliferating chondrocytes, while in the chick it was 146% higher. The data not only provides further evidence for a role of the c-myc protein in cell proliferation but also suggests involvement of this protein in chondrocyte differentiation and/or hypertrophy.

Oncogenes in gynecological tumors

Evidence is increasing that proto-oncogenes and cancer suppressor genes are involved in the development and/or progression of gynecological malignancies. While histopathologic examination remains an indispensable tool of the surgical pathologist in the diagnosis and evaluation of patients with gynecological malignancies, the advancement to technology and the development of new knowledge regarding neoplastic transformation are providing a basis for new opportunities to improve patients care. These new opportunities will depend on the use of the skills and reagents developed in the basic medical science laboratories. Thus, it is important for those in the field of diagnostic pathology to begin to acquire a knowledge of proto-oncogenes and cancer suppressor genes as well as a basic understanding of the techniques used to detect and evaluate them.

Endocervical carcinoma and precursor lesions: c-myc expression and the demonstration of field changes

The monoclonal antibody Myc 1-6E10 was used in an immunocytochemical technique to examine the expression of the c-myc oncogene in normal endocervices and those with glandular intraepithelial neoplasia and invasive malignancy. Eleven of 14 normal endocervical biopsy specimens did not express the gene, while three showed nuclear, or light basal cytoplasmic localisation of the gene product, or both. All but one of 14 cases of low and high grade glandular intraepithelial neoplasia, and all 17 cases of invasive adenocarcinoma, showed a pan-cellular pattern of immunostaining. Of considerable additional interest was the demonstration of field changes in morphologically normal glandular epithelium in those biopsy specimens with concurrent cervical glandular intraepithelial neoplasia or adenocarcinoma. This was manifest as increased concentrations of myc proteins compared with normal tissues. These results further support the role of the c-myc gene in oncogenesis, and in the light of field changes, suggest possible difficulties in the clinical management of this group of patients.

Prognostic value of flow cytophotometric DNA content analysis in single treatment stage IB-IIA squamous cell carcinoma of the cervix

DNA content was measured flow cytometrically in archival tissue from 65 single-treatment stage IB and IIA squamous cell carcinomas of the cervix with at least 5 years of clinical follow-up. Thirty-five cases were treated exclusively by hysterectomy and thirty exclusively by radiation therapy. Tumors were categorized into four groups on the basis of DNA content and cell cycle distribution. DNA content was measured relative to the position of the first resolvable cell peak. G2/M and S-phase fractions were estimated as percentage of cells with DNA contents greater than or equal to relative position 1.70 and percentage of cells with relative positions between 1.20 and 1.70, respectively. The 40 tumors characterized as either aneuploid or nondemonstrably aneuploid with high S-phase fraction estimate had a 5-year recurrence rate significantly higher than that of the 25 tumors categorized as tetraploid or nondemonstrably aneuploid with low S-phase fraction estimate (52 and 4%, respectively; chi 2 = 15.8, P less than 0.001). Similar results were found when radiation and surgically treated tumors were considered independently (chi 2 = 7.95, P less than 0.005 and chi 2 = 5.7, P less than 0.025, respectively). These data suggest that an increased 5-year recurrence rate is associated with both abnormal DNA content and elevated S-phase fraction in stage IB-IIA squamous cell carcinoma of the cervix, and that this relationship is largely independent of treatment method.

Oncogenes: a review of their clinical application

One objective of this review is to sort through and collate the recent data that suggest that human cellular oncogenes, which have been implicated as the etiologic agents in both animal and human malignancies, have also the potential to be employed as clinical tools in the struggle against cancer. For nearly 10 years, reports have been suggesting that advantage can be taken of cellular oncogenes as to their use as diagnostic and prognostic indicators of cancer and eventually as therapeutic cancer agents. It is also the purpose of this review to give an objective evaluation of these predictions. Moreover, this review will try to highlight some of the significant advances in this most rapidly evolving field of biology. Although the enormity of what has been learned about cellular oncogenes is nothing less than impressive, it is the view here that the routine implementation of oncogenes into the clinical setting will not become evident as early as the many predictions had purported.

Oncogene expression and prognosis in cervical cancer

Cancer of the uterine cervix accounts for 80-85% of all female genital tract malignancies in India and also remains a major problem for oncologists in other parts of the world. A major concern regarding the disease is the lack of specific tumor markers for early detection, for accurate prediction of biological behaviour and for accurate assessment of prognosis. A new and exciting answer to this issue may now be available with the description of specific oncogenes and oncoproteins associated with this malignancy. On a clinical level these genes and their products may allow us to improve our understanding of disease etiology, and provide more precise diagnostic, prognostic and therapeutic characterization of individual tumors. This paper discusses the possibilities of using altered expression of oncogenes and their products in neoplastic tissue as markers for the diagnosis and prognosis of cervical cancer. These data support the view that detailed analysis of such gene expression has the potential to predict tumor behavior.

Oncogene expression in cervical intraepithelial neoplasia and invasive cancer of cervix

Expression of the oncogenes Ha-RAS, c-MYC, and ERB-2 was investigated with an automated image analysis system in 12 specimens of normal cervix, 10 of cervical intraepithelial neoplasia (CIN) grade 1, 24 of CIN 3, and 10 of invasive cancer of the cervix. There was amplification of all three oncogenes in CIN 3 and invasive cancer compared with normal cervix and CIN 1. The difference was most pronounced with an antibody to the RAS p21 protein, with no overlap between CIN 3 and the normal range. This method might be useful in screening for cervical neoplasia, and for the determination of which CIN lesions require treatment.

Influence of tissue preparation techniques on p53 expression in bronchial and bladder carcinomas, assessed by immunofluorescence staining and flow cytometry

In a series of bronchial and bladder carcinomas, p53 protein expression was examined. Samples from formalin-fixed, paraffin-embedded tissue (routine-treated) were compared with parallel samples of fresh tissue and tissue fixed in paraformaldehyde and ethanol. The expression of p53 was measured by immunofluorescence staining and dual parameter flow cytometry, with simultaneous monitoring of DNA content. For each tumor, p53 fluorescence with different fixatives was expressed relative to fresh tissue. The p53 fluorescence signals were on average brighter from routine-treated tissue than from fresh tissue. The tissue fixed in paraformaldehyde showed no difference from fresh tissue. In the ethanol-fixed tissue, however, fluorescence signals were reduced by nearly 70%, and the fraction of detectable p53 positive cells in tumor tissue was reduced by more than 50%. This loss of fluorescence was probably due to a leakage of the antigen from nucleus to cytoplasm. Pepsin treatment did not influence p53 fluorescence. Within the same tumor, the S-phase fraction in p53 positive cells was significantly higher than in p53 negative cells (13.1 +/- 2.0% vs. 6.5 +/- 0.8%). This pattern was not influenced by formalin fixation or pepsin treatment. Our study demonstrates that in measuring a nuclear antigen, tissue handling may influence the results, and care should be taken to optimize the preparation procedure. Using the antibody PAb 1801, p53 expression measured in archival material is not reduced as compared to fresh tissue.

Tissue preparation for simultaneous flow cytometric quantitation of tumour associated antigens and DNA in solid tumours

A multiparameter flow cytometric assay for the simultaneous study of tumour associated antigens (TAA) and DNA in fresh solid tumours was devised. Cell suspensions were prepared by disaggregating unfixed solid tumour samples mechanically over a stainless steel mesh. Indirect immunofluorescence was used to identify the TAA, and DNA was stained with propidium iodide. Cell morphology was well preserved, cell clumping was negligible, and high quality indirect immunofluorescence quality indirect immunofluorescence and DNA staining were obtained. The technique is simple, rapid, and reproducible. Multiparameter assays can be developed to study prognostic indicators such as membrane oncoproteins, receptors, and multidrug resistance in solid tumours. With a suitable panel of antibodies the technique might become an aid in the differential diagnosis and biochemical diagnosis of some solid tumours.

Measurement of c-myc protein content and cell cycle kinetics of normal and spontaneously transformed murine mastocytes by bivariate flow cytometry

Progressive in vitro culturing of interleukin-3 (IL-3) dependent normal murine mastocytes (PB-3) resulted in a variant cell line (PB-1) able to grow without exogenous IL-3 and which was tumorogenic in syngenic mice. Bivariate flow cytometry was used to evaluate the c-myc protein and DNA content of PB-3 and PB-1 cells. The c-myc protein was detected by specific monoclonal antibodies. Kinetic characteristics of PB-3 and PB-1 cell lines, namely, the duration of the G1, S and G2 + M cell cycle phases were also evaluated using the bromodeoxyuridine (BrdU) pulse-chase method and BrdU/DNA flow cytometry. Levels of c-myc protein in PB-1 cells were about two-fold higher than those of PB-3 cells in all cell cycle phases. Mean duration of the cell cycle (Tc) was 15.3 h for PB-3 cells and 12.4 h for PB-1 cells. Shortening in Tc for the transformed cells was due to a decrease of nearly 30% in mean duration of the G1 phase (from 8 h to 5.7 h). No significant differences were found in the duration of the S and G2 + M phases. These results indicate that acquired IL-3 independency in vitro and tumorogenicity of PB-1 cells were accompanied by a doubling of c-myc protein level and by a parallel shortening, or bypass, of the regulatory events within the G1 phase of the cell cycle.

Ras oncogene expression and progression in intraepithelial neoplasia of the uterine cervix

To examine the correlations between ras oncogene expression and the development of cervical cancer, the authors studied the reactivity of cervical intraepithelial neoplasia (CIN) and microinvasive lesions of the human uterine cervix by using anti-ras p21 mouse monoclonal antibody rp35. The frequency of positive p21 staining increased with increased grades of malignancy from 17.9% in CIN 1 to 28.9% in CIN 2 and 53.9% in CIN 3, whereas in microinvasive carcinoma it was 50.0%. Furthermore, ten cases of lesions that regressed during a 1-year follow-up period were positive for ras p21 in 20% of cases, but 14 cases of lesions that progressed and developed into higher graded lesions during the 2- to 5-year follow-up period had a 50.0% rate of positive p21 staining. It was concluded that ras oncogene product p21 correlates with the early phase of carcinogenesis of squamous cells of the uterine cervix.

Comparison of deoxyribonucleic acid ploidy and nuclear expressed p62 c-myc oncogene in the prognosis of colorectal cancer

A simultaneous flow cytometric assay of the nuclear expressed protein product of the c-myc oncogene p62 and deoxyribonucleic acid (DNA) ploidy in archival paraffin-embedded tumor material was undertaken in 179 patients with colorectal cancer, followed for up to 9 years. DNA ploidy showed a survival advantage for diploid tumors (chi 2(1) = 5.39, p = 0.020) and could be used to further divide patients with Dukes' A tumors (chi 2(1) = 4.87, p = 0.027) and Dukes' C tumors (chi 2(1) = 5.33, p = 0.021). By dividing patients into 2 levels of tumor expression of p62 c-myc, there was a trend for improved survival in patients with low expression (chi 2(1) = 3.65, p = 0.056). A combination of ploidy status and p62 c-myc expression improved upon survival prediction by ploidy alone in providing 3 groups (chi 2(2) = 7.86, p = 0.0197). While these results do not suggest a replacement for the Dukes' staging for prognosis (chi 2(3) = 33.82, p less than 0.00001), they strongly support the concept that enhanced expression of c-myc oncogene is associated with the progression of colorectal cancer.

c-myc oncogene product expression and prognosis in operable breast cancer

The 62 kDa protein product of the c-myc oncogene (p62 c-myc) is thought to be involved in the control of normal cellular proliferation and differentiation. We have measured oncoprotein levels using a flow cytometric assay in 141 operable breast cancers and have correlated levels with prognostic variables, patient survival and disease free intervals. High levels of p62 c-myc were associated with well differentiated tumours. There was no correlation with tumour DNA index, lymph node or oestrogen receptor status. C-myc oncoprotein levels were not predictive of patient survival or disease free interval. This relationship of oncoprotein levels with tumour histological grade is in keeping with the suggestion that the c-myc oncogene is important in the control of cellular differentiation. The other findings imply that measurement of c-myc oncoprotein levels does not yield useful prognostic information.

Limitations in the measurement of c-myc oncoprotein and other nuclear antigens by flow cytometry

Recent developments in cell fixation, quantitative immunocytochemistry, and flow cytometry allow for the quantification of a variety of oncoproteins and other proliferation-associated antigens in both fresh and archival pathology material. These studies provide evidence that the standard tissue deparaffinization/dissociation technique significantly reduces the amount of c-myc oncoprotein remaining for analysis. To examine the factor(s) responsible for this observation, individual variables of the deparaffinization/dissociation technique including type of fixative, pepsin concentration, pepsinization times, pH, and exposure to organic solvents were examined in HeLa-S3 cells. The cells were stained with monoclonal antibodies either to the c-myc oncoprotein or to p105, a prolifera-tion-associated nuclear antigen. Protein-levels were measured on the basis of anti-c-myc or anti-p105 immunofluorescence by flow cytometry and were found not be affected significantly by type of fixative, exposure to organic solvents, acid pH solution, or mechanical disruption. Levels of c-myc oncoprotein were reduced by over 50%, however, when cells were exposed to 0.5% pepsin, whereas p105 was more resilient with only an approximately 7% reduction following the same treatment. Thus, careful examination of aspects of the deparaffinization/dissociation technique appears to be a necessary prerequisite for quantification of specific nuclear proteins from dissociated tissue specimens.

Flow cytometry using paraffin-embedded tissue: five years on

The use of paraffin-embedded tissue for flow cytometry is reviewed. A number of technical modifications of the original 1983 method have been described, aimed at improving the accuracy of DNA measurements by minimizing cell debris or reducing coefficients of variation, and at simplifying sample preparation. Over 100 clinical studies have now been reported, mainly assessing the effect of DNA index on prognosis, and those published up until mid-1988 are summarized in an appendix. More recently there have been developments in the use of monoclonal antibodies to measure oncogene products or proliferation markers in addition to DNA content. Detailed clinical evaluation and standardization of these more sophisticated methods is still some way ahead, but as was the case with DNA index, the use of archival material from patients whose outcome is already known should speed this process.

Simultaneous paired analysis by flow cytometry of surface markers, cytoplasmic antigens, or oncogene expression with DNA content

Flow cytometry is a useful tool for measuring DNA content and differentiation as expressed by cell surface markers. We have extended this technology to measure simultaneously either surface, cytoplasmic, or nuclear antigens (particularly oncoproteins) with DNA content. Mononuclear blood cells isolated from normal subjects and HL60 leukemic cells were permeabilized and fixed in suspension utilizing 40 micrograms/ml lysolecithin and 1% paraformaldehyde. A range of lysolecithin concentrations in 1% paraformaldehyde was studied to optimize permeabilization of the antibodies to the cell interior without destroying cell integrity. The optimal concentration (40 micrograms lysolecithin/ml) resulted in good cell recovery with a high percentage of cells positive for surface and intracellular antigens. Cells are first stained with fluorescein isothiocyanate conjugated (FITC) antimyeloperoxidase (an azurophil granule enzyme), or with an anti-c-myc antibody and FITC goat anti-mouse IgG F(ab')2. Cells are then incubated with RNase and stained for DNA content with propidium iodide. Alternatively, cells were stained for the cell surface markers Leu M3, OKM1, or the transferrin receptor and were then fixed and permeabilized and stained with propidium iodide. Using this method, we correlated cytoplasmic, nuclear, or cell surface antigens with cell cycle kinetics. This technique should be useful for studies of cellular differentiation and proliferation.

Papillomavirus and c-myc antigen expression in normal and neoplastic cervical epithelium

Cervical punch biopsy specimens or brushings were collected from 33 patients with cervical human papilloma virus (HPV) infection, cervical intraepithelial neoplasia (CIN), or invasive cervical carcinoma, and from eight control patients with recent normal cervical cytology. Prostatic chippings obtained from six men with benign prostatic hypertrophy were used as further controls. Biopsy specimens and brushings were assayed by flow cytometry for c-myc oncogene antigen and papillomavirus antigen expression and rate of cell division (by measuring DNA content). Results obtained from analysis of specimens and brushings were similar in terms of c-myc antigen and total DNA content, but when the percentages of nuclei from biopsy and brush specimens staining positively with antibody to papilloma viral antigens were compared, brush specimens gave consistently higher percentages than biopsy specimens. More specimens from normal epithelium were c-myc antigen positive (five of eight, (63%) than specimens from CIN II or III (two of 10, 20%), or invasive carcinoma (0%). No association was found between c-myc antigen expression and cell division. HPV antigen positive specimens were found to contain more dividing cells than negative specimens.

c-myc oncoprotein levels in bladder cancer

The protein coded by the oncogene c-myc, p62c-myc, was measured using monoclonal antibodies and flow cytometry in nuclei derived from paraffin-wax sections of transitional cell carcinomas of the human bladder. Superficial disease (stages pTa and pT1) which did not recur within 5 years of diagnosis had significantly higher oncoprotein levels than those which did recur or were muscle-invasive (stage pT2 or greater) at presentation (P less than 0.01). These preliminary findings indicate that oncoprotein levels might have prognostic significance for bladder cancer.

DNA aneuploidy in solitary colonic adenomas and the future risk of colorectal cancer

Flow cytometric DNA analysis was performed on the colonic adenomas of 24 patients who had resection of an invasive colorectal carcinoma subsequent to polypectomy. The incidence of DNA aneuploidy among these adenomas was only 13 percent. Thus, simple recognition of colonic adenomas as being DNA diploid or DNA aneuploid is unlikely to be helpful for identifying patients with adenoma who are at high risk for developing a future colorectal carcinoma.

Reactivity of monoclonal antibodies to oncoproteins with normal rat liver, carcinogen-induced tumours, and premalignant liver lesions

Monoclonal antibodies to proteins encoded by the ras, myb, myc, erb-B, src and PDGF-2 genes were tested for reactivity with normal rat liver, livers from rats fed with 0.06% 2-acetylaminofluorene (AAF), and premalignant lesions and primary liver tumours from rats given AAF alone or a combined treatment with diethylnitrosamine and AAF. Radioimmunoassays were performed with plasma membrane fractions and total soluble subcellular extracts of the tissues, and immunoperoxidase staining was carried out on frozen tissue sections. All of the antibodies were positive in radioimmunoassays, some more strongly than others, and each antibody bound equally to extracts of different kinds of tissue. Immunohistology revealed significant staining of normal liver by 5 of the 6 antibodies, and only minor qualitative differences of the staining pattern in some tumours and hyperplastic nodules. It was concluded that these antibodies were not able to discriminate sufficiently well between normal, premalignant and malignant rat liver to be of value in identifying the precursor cells of malignant tumours.

Structure and expression of c-myc and c-fos proto-oncogenes in thyroid carcinomas

Tumour specimens from 23 patients with thyroid carcinoma, 22 patients with thyroid adenoma, 3 with Graves' disease, and tissues from 8 normal thyroid glands were analyzed by Southern blot hybridization for the physical state of c-myc and c-fos proto-oncogenes. In 4 patients, both the primary tumour and lymph node metastases were analyzed. No amplification or rearrangement of the two proto-oncogenes was detected. Total RNAs were also analyzed. Elevated levels of the 2.4 kb c-myc RNA and of the 2.2 kb c-fos RNA were found in 13/23 (57%) and 14/23 (61%) of the cancer patients, respectively. High levels of c-myc transcripts were more frequently found in thyroid carcinomas with unfavourable prognosis. Concomitant elevated levels of both c-myc and c-fos RNAs were found in 8 cancers. High levels of c-myc RNA were also found in 1 out of 22 specimens of adenoma, in 1 specimen of Graves' disease and in 2 normal thyroid glands. High levels of c-fos RNA were found in 20 of the 22 adenoma samples and in 2 out of 8 normal thyroid tissues. These data indicate that the overexpression of c-myc and c-fos genes is independent of an alteration of the loci. The high levels of c-fos found in adenoma may be associated with the differentiation state of these tumours.

A critical appraisal of the immunohistochemical detection of the c-myc oncogene product in colorectal cancer

Expression of c-myc was studied immunohistochemically in 100 colorectal carcinomas, using a monoclonal antibody, Myc 1-6E10, which is purported to recognize the oncoprotein (p62c-myc) in paraffin-embedded material. In normal epithelium, maturing crypt cells and terminally differentiated surface cells were positive, and proliferating basal crypt cells negative. All carcinomas stained positively, but intensity was independent of histological differentiation, Dukes' stage, DNA ploidy and survival. Staining was predominantly cytoplasmic despite the suspected nuclear location of p62c-myc and there was considerable staining of fibroblasts. When staining was compared in frozen and paraffin-embedded sections fixed in different ways, different patterns were observed. Acetone-fixed frozen sections exhibited weak nuclear and cytoplasmic staining or were negative. In formol-saline fixed frozen sections, there was stronger predominantly nuclear staining. In paraffin-embedded sections staining was predominantly cytoplasmic. This study suggests that c-myc expression is enhanced in the majority of colorectal carcinomas and although independent of clinical behaviour, may be a common event in malignant transformation. However, since staining is affected by fixation and processing, data obtained using Myc 1-6E10 on routinely processed specimens should be interpreted with caution.

Abnormal distribution of c-myc oncogene product in familial adenomatous polyposis

Monoclonal antibodies raised by synthetic peptide immunisation were used to determine the distribution of the protein product of the c-myc gene by immunocytochemical staining of archival wax embedded material from patients with familial adenomatous polyposis. Polyps from 18 cases of familial adenomatous polyposis, 10 of whom had developed malignant change, and 30 normal control colonic biopsy specimens were examined. A consistent staining pattern was observed in normal mucosa; nuclear staining in the basal proliferative zone; mixed nuclear and cytoplasmic staining in the maturation zone; and cytoplasmic localisation in the surface mature zone. In contrast, the polyps and carcinomata showed a mixed pattern of cytoplasmic and nuclear localisation in the basal proliferative zone with nuclear persistence throughout the crypts to the surface mature zone. This abnormal distribution of the c-myc oncogene product may have a role in the evolution of polyps and their subsequent malignant transformation into familial adenomatous polyposis.

Oncogene expression in ovarian cancer: a pilot study of c-myc oncoprotein in serous papillary ovarian cancer

The nuclear-associated protein product of the c-myc gene, p62c-myc, was assayed simultaneously with total DNA using flow cytometry in nuclei extracted from archival biopsies of serous papillary carcinoma of the ovary. The oncoprotein was probed with a synthetic peptide-induced mouse monoclonal antibody which was subsequently labeled with a fluorescent rabbit anti-mouse immunoglobulin and DNA was assayed using the nucleic acid fluorochrome propidium iodide. Serous papillary ovarian carcinoma expressed significantly higher p62c-myc levels compared with normal ovary (P less than 0.00003 Mann-Whitney U test). Biopsies classified as "borderline" low-potential malignancy exhibited levels between normal ovary and carcinoma. The difference between normal and "borderline" was significant at P less than 0.003, but no difference between "borderline" and frankly invasive biopsies was observed, P = 0.149. There was no difference among the histological grades of carcinomas. All normal ovaries had diploid DNA content as did 5/6 cases of "borderline" malignancy. The majority of cases of carcinoma, 28/36, were aneuploid. There was a statistically significant difference in the distribution of aneuploidy, P less than 0.005, between invasive carcinomas and those classified as "borderline" low-potential malignancy.

Flow cytometric quantitation of the c-myc oncoprotein in archival neoplastic biopsies of the colon

The c-myc oncogene encoded protein product, p62c-myc, was assayed simultaneously with DNA in populations of individual nuclei extracted from archival biopsies of colonic neoplasia. Both the protein and DNA were assayed fluorimetrically using flow cytometry with a synthetic peptide induced monoclonal antibody (MYC 1-6E10) for the protein and propidium iodide for DNA. The nuclear p62c-myc levels increased progressively from normal mucosa through polyps to carcinomas. However, there was a trend for the more poorly differentiated carcinomas to exhibit lower levels than moderately and well-differentiated tumours, p = 0.085. These results agree with those published previously with the same antibody using Western blotting for protein extracted from fresh frozen tissue and immunocytochemical assessment. Furthermore, flow cytometry is able to effect discriminations between subsets in heterogeneous populations using DNA as a second parameter which Western blot bulk studies cannot.