Loss of sequences on the short arm of chromosome 17 is a late event in squamous carcinoma of the cervix

AIMS

To determine by fluorescence in situ hybridisation (FISH) whether deletion of D17S34, a subtelomeric probe for 17p, occurs in invasive squamous carcinoma of the cervix, and to determine the extent of such loss by analysis of the p53 and HER2/NEU genes.

METHODS

Fourteen invasive squamous cell carcinomas of the cervix were investigated by FISH for D17S34, p53, and HER2/NEU. Dual hybridisation of each probe with the chromosome 17 alpha satellite (D17Z1) probe was performed on paraffin wax embedded sections, and the fluorescence ratios of the paired signals were determined. Broad spectrum human papillomavirus (HPV) typing by ISH and GP5+/6+ polymerase chain reaction was also performed.

RESULTS

Twelve tumours were HPV positive, nine with HPV-16, and one each with types 18, 31, and 39. Loss of D17S34 was identified in four tumours, one of which was HPV negative. In one tumour, D17S34 loss was accompanied by loss of p53 only, suggesting that deletion was limited to the p arm. A second tumour showed simultaneous losses of all probes, indicative of whole chromosome 17 loss during tumour growth. The two remaining specimens showed loss of D17S34 only, diffuse in one, and localised within the tumour in the other. Aberrations of p53 or HER2/NEU were not seen independently of D17S34 loss, and loss did not correlate with HPV presence or type.

CONCLUSIONS

These data show that D17S34 loss is prevalent, marking 28% of the invasive squamous carcinomas in this study. The observed intratumoral heterogeneity indicates that, at least in some cases, this loss occurs after invasion and is therefore a late event in the path of cervical carcinogenesis.

Molecular approaches to identification of tissue contamination in surgical pathology sections

The finding of possibly contaminant tissues or cells in surgical or cytology case material can be a challenging problem in diagnostic anatomical pathology samples. The reported rates of occurrence have ranged from 0 to 8.8% (including prospective and retrospective cases). A diagnostically dissimilar tissue fragment, whether contiguous with other tissue or among other fragments within a paraffin section, and which is not incompatible with the case tissue, often requires a rigorous investigation to confirm or deny its relevance to the case. Fluorescence in situ hybridization using dual red and green DNA probes to regions of the X and Y chromosomes, respectively, were used in one case where the potential contaminant was suspected to have originated from a male patient. The putative contaminant tissue fragment was confirmed as male, with cells having one X and one Y chromosome, unlike the other tissue fragments on the slide with two X chromosomes. In a second case, DNA polymorphisms were used to compare allelic patterns that were informative not only in proving the extraneous tissue as a contaminant, but in addition, could be used to trace the latter to its original tissue source. The molecular tools of fluorescence in situ hybridization in sex-mismatched cases and of DNA microsatellite probes that are applicable to paraffin sections can provide definitive identifiers of tissues and individual cells. They are important adjuncts to histology for the anatomical pathologist when faced with the diagnostic problems of tissue contamination encountered in routine practice.

Significance of p53 mutations in patients with chronic lymphocytic leukemia: a sequential study of 30 patients

BACKGROUND

In patients with B-cell chronic lymphocytic leukemia (CLL), considerable disease heterogeneity within clinical stages necessitates the search for relevant prognostic indicators, particularly those that may help to determine the need for early therapeutic intervention. In the current study, the authors investigated the role of p53 mutations and chromosomal abnormalities in 30 patients with CLL.

METHODS

Thirty patients were screened for p53 mutations. Half of the group had aggressive disease characterized by leucocytosis, lymph node enlargement, organomegaly, and shortened tumor doubling time. Because 95% of p53 mutations reside in "hot-spot" regions of exons 5-9 of the p53 gene, the authors sequenced these exons completely for mutation detection.

RESULTS

Sequence analysis identified p53 mutations in 14 of 30 patients that were distributed equally among patients with aggressive disease and nonaggressive disease. There were six mutations in exon 7, five mutations in exon 5, and one mutation each in exons 6 and 8. Five of 15 patients with clinically aggressive disease had mutations in exon 7. Only one patient with nonaggressive disease had an exon 7 mutation. Abnormal cytogenetics were present in 22 of 30 patients (73%). Most patients with the p53 mutation (13 of 14 patients; 93%) displayed abnormal cytogenetics. Twelve of 15 patients with aggressive disease and 9 of 15 patients with average disease exhibited abnormal karyotypes.

CONCLUSIONS

The presence of p53 mutations did not predict clinical behavior or disease outcome, although the frequency of mutations appears to be higher than reported previously. In this study, mutations of exon 7 (5 of 6 patients) occurred in patients with clinically aggressive disease. The significance of this observation warrants further examination.

Malignant MCF10CA1 cell lines derived from premalignant human breast epithelial MCF10AT cells

The MCF10 series of cell lines was derived from benign breast tissue from a woman with fibrocystic disease. The MCF10 human breast epithelial model system consists of mortal MCF10M and MCF10MS (mortal cells grown in serum-free and serum-containing media, respectively), immortalized but otherwise normal MCF10F and MCF10A lines (free-floating versus growth as attached cells), transformed MCF10AneoT cells transfected with T24 Ha-ras, and premalignant MCF10AT cells with potential for neoplastic progression. The MCF10AT, derived from xenograft-passaged MCF10-AneoT cells, generates carcinomas in approximately 25% of xenografts. We now report the derivation of fully malignant MCF10CA1 lines that complete the spectrum of progression from relatively normal breast epithelial cells to breast cancer cells capable of metastasis. MCF10CA1 lines display histologic variations ranging from undifferentiated carcinomas, sometimes with focal squamous differentiation, to well-differentiated adenocarcinomas. At least two metastasize to the lung following injection of cells into the tail vein; one line grows very rapidly in the lung, with animals moribund within 4 weeks, whereas the other requires 15 weeks to reach the same endpoint. In addition to variations in efficiency of tumor production, the MCF10CA1 lines show differences in morphology in culture, anchorage-independent growth, karyotype, and immunocytochemistry profiles. The MCF10 model provides a unique tool for the investigation of molecular changes during progression of human breast neoplasia and the generation of tumor heterogeneity on a common genetic background.

Research potential of a unique xenograft model of human proliferative breast disease

A workshop on the 'Research potential of a unique xenograft model of human proliferative breast disease' was held at the Karmanos Cancer Institute, Wayne State University, Detroit, Michigan, in November of 1998. The accumulated information and current experimental findings on the MCF10AT model of preneoplastic, proliferative breast disease were reviewed. Discussions focused on the relevance of the model to clinical breast cancer and on the most profitable lines of further research to strengthen its utility.

Race and differences in breast cancer survival in a managed care population

BACKGROUND

African-American women with breast cancer have poorer survival than European-American women. After adjustment for socioeconomic variables, survival differences diminish but do not disappear, possibly because of residual differences in health care access, biology, or behavior. This study compared breast cancer survival in African-American and European-American women with similar health care access.

METHODS

We measured survival in women with breast cancer who are served by a large medical group and a metropolitan Detroit health maintenance organization where screening, diagnosis, treatment, and follow-up are based on standard practices and mammography is a covered benefit. We abstracted data on African-American and European-American women who had been diagnosed with breast cancer from January 1986 through April 1996 (n = 886) and followed these women for survival through April 1997 (137 deaths).

RESULTS

African-American women were diagnosed at a later stage than were European-American women. Median follow-up was 50 months. Five-year survival was 77% for African-American and 84% for European-American women. The crude hazard ratio for African-American women relative to European-American women was 1.6 (95% confidence interval [CI] = 1.1-2.2). Adjusting only for stage, the hazard ratio was 1.3 (95% CI = 0.9-1.9). Adjusting only for sociodemographic factors (age, marital status, and income), the hazard ratio was 1.2 (95% CI = 0.8-1.9). After adjusting for age, marital status, income, and stage, the hazard ratio was 1.0 (95% CI = 0.7-1.5).

CONCLUSION

Among women with similar medical care access since before their diagnoses, we found ethnic differences in stage of breast cancer at diagnosis. Adjustment for this difference and for income, age, and marital status resulted in a negligible effect of race on survival.

Chromosomal aberrations identified in culture of squamous carcinomas are confirmed by fluorescence in situ hybridisation

AIMS

Chromosomal aberrations in tumour cells are often not discernable by direct analysis. Although cell culture allows qualitative analysis of the karyotype, potential selection and evolution during growth in vitro may yield misleading data. To determine whether aberrations observed in vitro are representative of the original lesion, chromosomal aberrations found after prolonged growth in vitro of two squamous cell carcinomas of the head and neck (SSCHN) were evaluated with fluorescence in situ hybridisation (FISH) on the original tumour nuclei.

METHODS

Specific karyotypic aberrations identified in cultures of two squamous cell carcinomas were targets for FISH analysis on tumour sections. Chromosome painting mixtures were selected based on in vitro karyotypic data. FISH was performed on cultured interphase and metaphase cells, and on histological sections from the original tumours.

RESULTS

The 9cen and 17cen probes yielded FISH signals consistent with the aneusomies predicted for the respective chromosomes from the culture karyotypes. Whole chromosome 9 paint confirmed the prior existence in the tumours of i(9p) and i(9q), although only the latter hybridised with the 9cen probe. FISH data also supported in vivo representation of the diploid and tetraploid tumour subclones observed in cultures. In tumour HFH-SCC-8a, FISH results were generally concordant between cultured interphase and metaphase cells and the histological sections, and improved the interpretation of marker chromosomes identified in culture.

CONCLUSION

The karyotypes obtained in these cases after prolonged passage in culture were consistent with the genetic alterations in the original tumours.

Trisomy 6 as a primary karyotypic aberration in hematologic disorders

We identified seven patients with hematologic disorders and trisomy 6 as the sole karyotypic aberration in bone marrow aspirates or unstimulated peripheral blood. Five patients were male and two were female; all were adults with ages ranging from 22 to 74 years. Three of the seven patients presented with manifestations of peripheral cytopenia. Their bone marrows were hypocellular with slight or no dysplastic changes and without an increase in blasts. One of these patients subsequently developed acute myeloid leukemia (AML-M1). The four remaining patients were initially diagnosed with AML--three consistent with French-American-British classification of M1 and M4 in the fourth patient. These results suggest that trisomy 6 is a nonrandom primary numerical anomaly of myeloid disorders. The association of cytopenia and hypoplastic bone marrow with trisomy 6 may constitute a new, distinctive variant among myelodysplastic syndromes.

A new BRCA1 mutation in a Filipino woman with a family history of breast and ovarian cancer

Mutation of the BRCA1 gene in well-defined breast cancer families has been associated with an 87% lifetime risk for breast cancer and a 44% risk for ovarian cancer. Recent data indicate that the risk associated with these mutations is considerably lower, although still far greater than the risk for disease in the rest of the population. Approximately 81% of the mutations that have been identified have been frameshift (71%) or nonsense (10%) mutations, and either may result in a truncated protein. The protein truncation test (PTT) is often used to screen patients at high risk, because sequencing of this large (100 kb) gene with its 22 coding exons is an arduous task. The PTT was used to analyze genomic DNA and RNA from the peripheral blood of a 31-year-old Filipino woman with a poorly differentiated, stage 2A breast carcinoma and a family history of breast-ovarian cancer. PTT identified the wild-type protein fragment and an additional truncated protein fragment in the patient's sample. Subsequent direct sequencing of the appropriate coding region revealed a point mutation in exon 11 at nucleotide 2178, resulting in a C > T transition that caused a termination (stop codon) in amino acid 687. To our knowledge, this is the first report of mutation of the BRCA1 gene in a Filipino family, and this in-frame stop-codon mutation has not been reported previously.

Direct action of estrogen on sequence of progression of human preneoplastic breast disease

We have used the MCF10AT xenograft model of human proliferative breast disease to examine the early effects of estradiol exposure on morphological progression of preneoplastic lesions and to define the step(s) in the morphological sequence at which estrogen may act. The effects of estradiol on neoplastic progression of estrogen-receptor-positive MCF10AT cells in the orthotopic site were examined in ovariectomized female nude mice that received subcutaneous administration of implants of 17beta-estradiol or placebo pellets. At 10 weeks, histological analysis of the lesions derived from the estrogen-supplemented group revealed that 92% of lesions displayed histological features of atypical hyperplasia, carcinoma in situ, or invasive carcinoma, and the remaining 8% exhibited histological features of moderate hyperplasia. These highly proliferative lesions are in marked contrast to the control group in which 60% of samples displayed no evidence of hyperplasia. In contrast with control xenografts, estrogen-exposed xenografts demonstrated extensive areas of papillary growth, adenosis-like areas, prominent host inflammatory infiltration, and angiogenesis. Our results suggest that estrogen exerts a growth-promoting effect on benign or premalignant ductal epithelium by enhancing 1) the frequency of lesion formation, 2) the size of lesions, 3) the speed of transformation from normal/mild hyperplasia to those with atypia, 4) the degree of dysplasia, and 5) angiogenesis.

Assessing genetic markers of tumour progression in the context of intratumour heterogeneity

This is a report from the Kananaskis working group on quantitative methods in tumour heterogeneity. Tumour progression is currently believed to result from genetic instability and consequent acquisition of new genetic properties in some of the tumour cells. Cross-sectional assessment of genetic markers for human tumours requires quantifiable measures of intratumour heterogeneity for each parameter or characteristic observed; the relevance of heterogeneity to tumour progression can best be ascertained by repeated assessment along a tumour progressional time line. This paper outlines experimental and analytic considerations that, with repeated use, should lead to a better understanding of tumour heterogeneity, and hence, to improvements in patient diagnosis and therapy. Four general principles were agreed upon at the Symposium: (1) the concept of heterogeneity requires a quantifiable definition so that it can be assessed repeatably; (2) the quantification of heterogeneity is necessary so that testable hypotheses may be formulated and checked to determine the degree of support from observed data; (3) it is necessary to consider (a) what is being measured, (b) what is currently measurable, and (c) what should be measured; and (4) the proposal of working models is a useful step that will assist our understanding of the origins and significance of heterogeneity in tumours. The properties of these models should then be studied so that hypotheses may be refined and validated.

Chromosomal markers: signposts on the road to understanding neoplastic disease

Classical cytogenetic studies have defined chromosomal attributes of tumors that are useful at present in the diagnosis, classification, and management of leukemic disorders, and in some solid tumors as well. Recent advances in molecular techniques now permit application of some forms of chromosomal analysis to studies in cytopathology. However, to fully understand the present and potential uses of these tumor markers, it is necessary to have some background and perspective on classical cytogenetics.

Cytogenetic aberrations and DNA ploidy in soft tissue sarcoma. A Southwest Oncology Group Study

We performed cytogenetic analysis and determined DNA content by flow cytometry (FCM) on freshly disaggregated tumor biopsies from 45 patients with soft tissue sarcomas (STS). Cytogenetically aberrant clones characterized 30 (67%) tumors, with the remaining 15 yielding normal karyotypes with or without nonclonal aberrations. No tumors with multiple unrelated clones were observed. Among the 30 tumors with clonally abnormal karyotypes, 21 (70%) had near-diploid stemlines, six were near-triploid and three were near-tetraploid. Ten of the clonally aberrant tumors contained nonrandom chromosomal translocations characteristic of histologic subtypes. Overrepresentation of chromosomes 7 and 8 were common numerical aberrations. Structural aberrations most often involved chromosomes 1, 7, 9, 12, and 14. Clustering of breaks in 9p resulting in partial loss of the short arm was frequent. Unstable aberrations including rings, dicentrics, large markers, small numbers of double minutes, and telomeric associations were seen in nine tumors. With FCM, 27 (60%) tumors had aneuploid DNA content and 18 (40%) were DNA diploid. Of those 18 DNA diploid tumors, 11 showed clonal karyotypic aberrations. In addition, apparent discrepancies between the results of the cytogenetics and FCM with respect to ploidy pattern were seen in 13 samples; 11 had DNA content in the peritriploid to peritetraploid range but the corresponding karyotype was normal or near-diploid. When the findings of the cytogenetics and DNA content analyses were combined, an abnormal cell population by one or both methods was detected in 38 (84%) tumors. The concurrent application of standard cytogenetics and DNA ploidy by FCM provide complementary information confirming a high incidence of genetic alterations in STS.

HER-2/neu gene amplification characterized by fluorescence in situ hybridization: poor prognosis in node-negative breast carcinomas

PURPOSE

The HER-2/neu gene codes for a membrane receptor protein that is homologous, but distinct from the epidermal growth factor receptor. This investigation was performed to validate fluorescence in situ hybridization (FISH) as a sensitive and specific method for assessing HER-2/neu gene amplification in archival tissue and to test whether this alteration is associated with poor prognosis.

MATERIALS AND METHODS

HER-2/neu gene amplification was determined by FISH in 140 archival breast cancers, previously characterized for gene amplification by Southern hybridization or dot-blot hybridization, and for gene expression by Northern hybridization, Western immunoblot, or immunohistochemistry. A separate cohort of 324 node-negative breast cancers was assessed for amplification by FISH to determine the utility of HER-2/neu gene amplification.

RESULTS

Relative to solid-matrix blotting procedures, FISH analysis of HER-2/neu gene amplification showed a sensitivity of 98% and a specificity of 100% in 140 breast cancers. Among patients treated by surgery only, the relative risks (relative hazard) of early recurrence (recurrent disease within 24 months of diagnosis), recurrent disease (at any time), and disease-related death were statistically significantly associated with amplification. The prognostic information contributed by HER-2/neu amplification was independent of the other markers studied.

CONCLUSION

FISH was an alternative technique for determining gene amplification and had some distinct advantages over Southern hybridization. Our results demonstrate that HER-2/neu gene amplification in the absence of adjuvant therapy is an independent predictor of poor clinical outcome and is a stronger discriminant than tumor size. Women with small tumors that had gene amplification were at increased risk of recurrence and disease-related death.

New directions in breast cancer research

Research in breast cancer extends in many directions, stimulated by concerns related to the high incidence of the disease and the relative unpredictability of its clinical course. Examples of work in several directions are presented here arranged by four levels of analysis. 1) Molecular, intracellular events (molecular genetics). Recent identification of genes that predispose to breast cancer, and the isolation of those genes and their protein products, permit investigations of the most critical issues: the roles of these genes in normal development and breast differentiation, and how their alteration permits or contributes to tumor initiation. Thus, we expect that understanding the functions of the genes involved in inherited susceptibility to breast cancer will also be informative for sporadic breast cancers. 2) Cellular biology (cellular models for preneoplastic disease). We examine models of breast cancer development and ask how they help to validate a morphologic sequence for human breast neoplasia and whether they permit investigation of how to modify disease progression. Two useful models, one in transgenic mice and the other using human breast stem cells capable of culture and xenograft growth, are now available. 3) Tissue and organ (the tumor and its local environment). We look at the relationship of the tumor cell population to its local environment (stroma, blood vessels, etc.). This leads naturally to questions of how neighboring tissues and cytokines may modify tumor growth. 4) The individual as an organism and member of a population (hormonal rise and chemoprevention). We address identification of the primarily hormonal risk factors and a possible related mode of cancer prevention.

ras and p53 genes in male breast cancer

We have studied the roles of Ki-ras oncogene and p53 tumor suppressor gene in a series of 20 cases of male breast cancer and one papilloma of the male breast. Ki-ras was detected in 50-microns sections after digestion with proteinase K and SDS. DNA was amplified by polymerase chain reaction, dot blotted, and mutations were screened with labeled ras mutation-specific oligonucleotides. Wild-type and mutant p53 protein were detected with antibodies CM1 and DO7, using the avidin-biotin-peroxidase method. Two of 17 carcinomas showed Ki-ras mutations, both in codon 12 (gly --> lys and gly --> arg). Five of 20 male breast cancers (25%), including one large intraductal carcinoma, expressed mutant p53 protein. Although the incidence of mutant p53 expression in male breast cancer is similar to that in women, Ki-ras mutations are not significantly increased.

The biological significance of the multidrug resistance gene MRP in inversion 16 leukemias

Multidrug resistance represents an important mechanism by which leukaemic and solid tumour cells escape cell death after exposure to anthracyclines and other natural products. Acute myeloid leukaemia (AML) associated with the inversion chromosome 16: inv(16)(p13q22) has a favourable prognosis and is known to be chemosensitive. The inversion chromosome is seen in a number of FAB subclasses but is most commonly associated with acute myelomonocytic leukaemia with abnormal eosinophils, M4Eo. It results in the creation of a fusion between the myosin heavy chain gene (MYH11) on the short arm and the gene for a transcription factor, core binding factor beta (CBFB) on the long arm. In a subset of these inv(16) AML patients, inversion also results in loss of the gene for the multidrug resistance protein (MRP) at the short arm breakpoint. This gene maps to 16p13.13, centromeric to the primary short arm breakpoint, separated from MYH11 by a distance of approximately 150kb. Deletion of the MRP gene has been demonstrated by in situ hybridisation, gene dosage studies and by loss of heterozygosity of a flanking microsatellite marker (D16S405). Twenty two patients with inv(16) leukaemia were analysed for deletion of the MRP gene. Deletion of the gene was detected in seven patients, fourteen patients showed retention of the gene and in one case the findings were indeterminate. Clinical data from 13 of these patients were analysed revealing deletion of the MRP gene to be significantly associated with longer time from diagnosis until failure (death or relapse from complete remission) in these patients (p = 0.007). From this work and the growing literature concerning MRP, it appears likely that the deletion of an MRP allele, may favourably affect the biology of inv(16) AML and may have important prognostic implications.

INT2 and ERBB2 amplification and ERBB2 expression in breast tumors from patients with different outcomes

The relationships of INT2 and ERBB2 amplification and of ERBB2 overexpression in primary breast tumors to prognostic factors, recurrence, and survival have generated considerable controversy. The rationale for this study is that long-term, recurrence-free survival is a more direct criterion for testing the validity of a tumor marker than correlation either with prognostic factors or with short-term recurrence and survival. We examined the association of recurrence with INT2 and ERBB2 amplification and ERBB2 expression by comparing primary breast tumors from patients surviving without recurrence for > or = 8.5 years after diagnosis, the LTS group, to tumors from patients recurring within two years, the RR group. The RR (N = 63) and LTS (N = 61) samples were coded and examined for amplification by Southern blotting and for expression by immunohistochemistry. Comparison between the RR and LTS groups demonstrated that INT2 amplification was associated with a significantly (P = 0.018) higher (5.6-fold) risk of recurrence, an association that remained significant after controlling for lymph node (LN), tumor size (TS), and histograde (HG) status. ERBB2 amplification and expression were not associated with a higher recurrence risk. Survival analyses within the RR group, however, demonstrated significantly shorter survival time among cases with than without ERBB2 amplification (P = 0.018, median survival 16 vs 25 months), or ERBB2 expression (P = 0.019, median survival 15 vs 25 months), but not INT2 amplification. Univariate Cox proportional hazards regression models also demonstrated significantly shorter survival among cases with ERBB2 amplification (P = 0.016) or expression (P = 0.049), that remained significant in multivariate analyses (P = 0.022) for ERBB2 amplification. These results indicate a significant positive association between INT2 amplification and risk for tumor recurrence in the RR as compared to the LTS group. The relationship of ERBB2 amplification or overexpression to patient outcome is more complex. ERBB2 amplification and expression have a significant relationship with shorter survival among patients recurrent within two years, but their occurrence in tumors from women surviving without recurrence for > or = 8.5 years suggests that ERBB2 status is not predictive of shorter survival for all breast cancers.

MCF10AT: a model for the evolution of cancer from proliferative breast disease

A human cell line (MCF10A) originated from spontaneous immortalization of breast epithelial cells obtained from a patient with fibrocystic disease. MCF10A cells do not survive in vivo in immunodeficient mice. However, T24 c-Ha-ras oncogene-transfected MCF10A cells (MCF10AT) form small nodules in nude/beige mice that persist for at least 1 year and sporadically progress to carcinomas. By reestablishing cells in tissue culture from one of the carcinomas, a cell line designated MCF10AT1 was derived that forms simple ducts when transplanted in Matrigel into immunodeficient mice. With time in vivo, the epithelium becomes proliferative and a cribriform pattern develops within the xenografts. A significant number progress to lesions resembling atypical hyperplasia and carcinoma in situ in women, and approximately 25% progress to invasive carcinomas with various types of differentiation including glandular, squamous, and undifferentiated. Cells have been established in culture from lesions representing successive transplant generations. With each generation, cells are somewhat more likely to progress to high risk lesions resembling human proliferative breast disease. Although the incidence of invasive carcinoma remained fairly constant at 20 to 25%, the frequency of nodules showing proliferative breast disease rose from 23% in the first transplant generation to 56% in the fourth transplant generation.

Fluorescence in situ hybridization (FISH): a user's guide to optimal preparation of cytologic specimens

Fluorescence in situ hybridization (FISH) is a reliable method for tagging centromeric regions of specific chromosomes in interphase nuclei. Not only is FISH useful for chromosome enumeration, but as region-specific chromosome probes are developed, the clinical applications and potentials for use by pathologists are extensive. This technique lends itself particularly to use in cytology preparations because the cells are disaggregated and monolayer preparations yield excellent technical hybridization results. Over a 7-mo period we processed cytologic samples in an attempt to define and outline a method for optimal specimen processing for FISH use in cell suspensions, techniques applicable to all fresh cytology specimens which can also be used for the processing of surgical pathology aspirates and other material. All samples should be promptly processed to ensure specimen viability, and triaged on an individual basis to ensure preparation of moderately cellular monolayered cytospins. Equivalent nuclear probe signals have been obtained with several sample fixation methods: air-drying, 95% ethanol, methanol (Diff-Quik fixative), and Carnoy's solution. No difference was noted in the nuclear probe signals or specimen adhesion on positively charged or noncharged slides. After initial fixation our slides remained at room temperature until FISH was performed, without any adverse effects. A short digestion with proteinase K and subsequent rehybridization yielded positive results on samples that originally yielded poor nuclear probe signals.

Cytogenetic correlation with disease status and treatment outcome in advanced stage leukemia post bone marrow transplantation: a Southwest Oncology Group study (SWOG-8612)

A retrospective cytogenetic study was performed to determine whether non-random chromosome aberrations were related to the outcome of marrow transplantation for advanced stage acute leukemia (AL) and chronic myelogenous leukemia (CML). The patients were registered on SWOG-8612, a randomized comparison of busulphan and cyclophosphamide (BU/CY) to fractionated total body irradiation and etoposide (FTBI/VP16) as preparatory regimens for allogeneic bone marrow transplant (BMT). Blume K. G., Kopecky K. J., Henslee-Downey J. P., Forman S. J., Stiff P. J., Le Maistre C. F. & Appelbaum F. R. (1987) Blood 81, 2187. Pretreatment cytogenetic studies were available for 90 (78%) of the 115 patients who proceeded to BMT. Patients were categorized by diagnosis (ALL/AML/CML), disease status ['good' risk = second complete remission (CR2) or CML-accelerated phase (AP); 'poor' risk = third complete remission (CR3), induction failure, florid relapse or CML-blast phase (BP)] and cytogenetic status (favorable = normal cytogenetics in AL or Philadelphia chromosome positive (Ph+) standard or variant translocation as the sole findings in CML; unfavorable = all other cytogenetic aberrations). Chromosomal aberrations observed in the unfavorable category included -7, t(9;22) in AL, t(8;21) in association with complex karyotypes, t(6;9), del(9q), t/del(11q), t(1;19), hypotetraploidy, and complex karyotypes (> 3 cytogenetic anomalies). Unfavorable cytogenetic status was significantly more frequent among patients with 'poor' risk clinical disease status (P < 0.0001). In multivariate analysis, disease-free survival (DFS) was significantly poorer for patients with unfavorable cytogenetic status (P = 0.002) but not significantly related to disease status (P = 0.43). These data indicate that certain secondary chromosome aberrations [+8,i(17q), duplication of Ph] should be reclassified as relatively favorable predictors of successful BMT in CML and, therefore, be separated from the unfavorable cytogenetic aberrations characteristic of drug resistant disease [-7, inv(3), complex karyotypes]. The limited number of patients precluded definitive assessment of the prognostic significance of specific cytogenetic aberrations for any single diagnosis. Nevertheless, these findings suggest that cytogenetic status may be an important and independent factor in predicting outcome following allogeneic bone marrow transplantation.

Breast cancer in males: DNA content and sex chromosome constitution

The infrequent occurrence of breast cancer in males may reflect different etiologic factors and decreased hormonal dependence in comparison with the disease in females. We have attempted to define genetic differences in tumors of males that might reflect alterations in pathogenesis, by examining 22 tumors and 11 examples of gynecomastia for ploidy in relation to X- and Y- chromosome copy number by fluorescence in situ hybridization. Ploidy values were obtained for 15 infiltrating ductal and four papillary tumors (three invasive and one intraductal), two ductal carcinomas in situ, one papilloma, and 11 cases of gynecomastia by flow cytometry of disaggregated cells from the paraffin blocks. The malignant papillary lesions and 14 of the ductal tumors were examined by fluorescence in situ hybridization. DNA probes for pericentromeric regions of the X and Y chromosomes were reacted with formalin-fixed paraffin-embedded sections using a combination of avidin-biotin, digoxigenin-antidigoxigenin, and direct-labeling techniques. Seven multimodal tumors, including one carcinoma in situ, were clearly aneuploid by flow cytometry; the remaining 14 malignant tumors, the papilloma, and 11 examples of gynecomastia were within the diploid range. In two cases, aneuploid-tetraploid clones in tumors that were not recognized by flow cytometry were detected as subpopulations because of extra copies of the X and Y chromosomes. Two cases with aneuploid subpopulations by fluorescence in situ hybridization showed evidence of excess X-chromosome copy number, suggestive of preferential increase of this chromosome within the tumor, and the fluorescence in situ hybridization results also supported exclusion of constitutional Klinefelter's syndrome, although mosaicism could not be excluded.

Detection of M-bcr/abl fusion by fluorescence in situ hybridization (FISH) in a case of Ph negative CML

A balanced reciprocal translocation, t(6;9)(p21;q34), was identified in a female patient diagnosed with chronic myeloid leukemia (CML). Both homologs of chromosome 22 were of normal length and morphology. Southern blotting revealed a bcr rearrangement with BglII and HindIII. Two signals for the abl probe were demonstrated by fluorescence in situ hybridization (FISH), one on the normal chromosome 9 and the second on a chromosome 22. Thus, molecular rearrangement of bcr resulted from insertion of an abl gene within the bcr region despite absence of a Ph chromosome.

Common clonal origin of synchronous primary head and neck squamous cell carcinomas: analysis by tumor karyotypes and fluorescence in situ hybridization

Two synchronously arising primary squamous cell carcinomas (SCC) originating from separate sites in the anterior floor of mouth (FOM) and the pyriform sinus (PS) were evaluated by karyotype and fluorescence in situ hybridization (FISH) to determine whether they were of common or independent ancestry. The primary tumors were designated Henry Ford Hospital (HFH)-SCC-8a (FOM) and HFH-SCC-9a (PS), and the respective recurrent tumors after chemotherapy and radiation were designated -8b and -9b. HFH-SCC-8a and -8b were cultured and had closely related hypotetraploid karyotypes of monoclonal origin. Karyotypes could not be obtained from the second primary tumor HFH-SCC-9a or its recurrence -9b. However, we used karyotypes from HFH-SCC-8a and -8b as a guide to select FISH probes for the histological evaluation of genetic markers in tumor sections. Fluorescence in situ hybridization on metaphase chromosomes from the cell cultures was useful in modifying the tumor karyotypes. Fluorescence in situ hybridization identified a chromosome Y rearrangement that was not obvious from the HFH-SCC-8a and -8b karyotypes, and this Y rearrangement served as a unique clonal marker. Using two probes for the Y chromosome we showed that all four tumors shared the same Y rearrangement with loss of Yq (DYZ1) and retention of Ycen (DYZ3). Furthermore, FISH showed that all four tumors had the same aneuploidy patterns for chromosomes X, Y, 7, 9, 15, 16, and 17. From karyotypic and FISH analysis disomy for X and 9 centromere regions and the rearranged Y were all predicted and observed in the tumor tissue sections. Tetrasomy and trisomy for 7, 15, 16, and 17 were predicted from the karyotypes and this also was observed using FISH in all four tumors. These FISH aneuploidy patterns and the presence of a clonal Y marker in all four tumor samples indicate that the synchronous primaries and their recurrences were of monoclonal origin.

Chromosomal aberrations in two adrenocortical tumors, one with a rearrangement at 11p15

Adrenocortical tumors are detected with increasing frequency, but symptomatic cases with excessive hormone production are rare. We investigated cytogenetically one benign aldosterone-producing tumor (Conn Syndrome)(case 1) and one malignant cortisol-producing tumor (Cushing Syndrome)(case 2). Radioimmunoassay of cell culture supernatant of case 2 detected cortisol secretion during 2 months in culture. Flow cytometry of spill-out cells from case 2 showed a bimodal pattern (DNA Index 1.0, 1.4). Case 1 revealed a marker chromosome in 4/25 cells analyzed; the marker was a long acrocentric partially derived from chromosome 2,der(2q). In case 2, a cytogenetic harvest was achieved after prolonged culture time (6 weeks) and a marker chromosome, add(11)(p15), was detected in 16/22 cells. A breakpoint of 11p13, as well as loss of heterozygosity of alleles on 11p15, has been reported in the literature for other malignant adrenocortical cancers.

Deletion of gene for multidrug resistance in acute myeloid leukaemia with inversion in chromosome 16: prognostic implications

Acute myeloid leukaemia (AML) associated with an inversion in chromosome 16 has a relatively favourable prognosis. The AML subclass most commonly associated with this chromosomal abnormality is acute myelomonocytic leukaemia with abnormal eosinophils. In some AML patients with inversion 16 the chromosomal lesion results in deletion of MRP, the gene for multidrug resistance associated protein. This gene is proximal to the primary breakpoint and loss of its function may play a key role in determining the favourable outcome in inversion 16 AML. We have demonstrated deletion of MRP by in situ hybridisation, by gene dosage studies and by studying loss of heterogeneity of a flanking microsatellite marker. Among 13 AML patients with inversion 16 MRP deletion was detected in 5 while 7 had no deletion. Deletion of MRP gene was associated with longer time from diagnosis until death or relapse from complete remission (p = 0.007). These findings provide important insight into the biology of inversion 16 leukaemia and suggest that MRP deletion, as detected by molecular analysis, may have a key role in determining outcome in patients with inversion 16 AML.

Allelic loss in locally metastatic, multisampled prostate cancer

In order to determine whether retention or loss of potential tumor suppressor loci that map to 8p, 10q, or 16q reflect genetic relationships among prostatic intraepithelial neoplasias (PINs), multicentric primary prostatic cancers, and regional lymph node metastases or are associated with the metastatic phenotype, we analyzed 19 cases of locally metastatic prostate carcinoma (stage D1) utilizing polymerase chain reaction techniques. In each case, tissue samples from metastatic tumor, the (dominant) primary tumor, and nonneoplastic prostatic tissue were examined. In selected cases, allelic loss in additional tumor foci, separate from the dominant tumor nodule, and areas of PIN were examined. Allelic loss of sequences on 8p, 10q, and 16q were observed in 20-29% of PINs, 18-42% of primary tumors, and 8-25% of metastatic tumors. Discrepancies in sequence dosage between histological components were most pronounced for 8p sequences, especially between the dominant tumor nodule and metastatic deposits in cases in which > or = 3 separate tumor foci/gland were identified. These results suggest that putative premalignant lesions, moderately or poorly differentiated, geographically separate primary tumor foci, and metastases within morphologically "complex" prostates (those with > or = 3 foci/gland) are likely to be more discordant for sequence dosage at 8p than those within "simpler" glands (< 3 foci/gland). Also, our results suggest that lymph node metastases may be genetically related to either the dominant or additional primary tumor foci in more complex prostates and that accumulation of genetic aberration may differ in primary and metastatic lesions.

Fluorescence in situ hybridization: a new tool for the pathologist

DNA in situ hybridization methods permit investigations of genetic alterations within the context of cell morphology and tissue architecture and are of particular importance in tumor pathology. Detection of specific chromosome aberrations may be a critical adjunct to diagnosis or prognosis when morphology is ambiguous. This approach will lead to better understanding of heterogeneity in tumors and to better definition of premalignant lesions.

Chromosomal markers of immortalization in human breast epithelium

We describe a series of five immortal breast cell lines that have emerged independently from diploid cultures from two individuals. We have karyotyped representative cultures of each of these lines prior to and at intervals after immortalization. Although considerable diversity of chromosomal aberration was found among the five lines, analysis of sublines has defined the chromosomal changes common for each immortalization. These changes differed both within and between the individual patient sources. Some common alterations were noted in lines from both patients, however, including loss of the short arm of chromosome 20 and gain of 1q. We suggest that genes within these chromosomal regions contribute to spontaneous immortalization of human breast epithelium.

Chromosomal aneuploidy in proliferative breast disease

Although some forms of proliferative breast disease have been associated with increased risk of breast cancer, substantial confirmatory evidence that the lesions are biologically premalignant has not been presented. Our intent was to identify cytogenetic aberrations in proliferative breast disease using fluorescence in situ hybridization probes selected for their relationship to aberrations previously reported in breast cancer. Application of fluorescence in situ hybridization techniques to paraffin tissue sections using pericentromeric probes for chromosomes 1, 16, 17, 18, and X revealed chromosome aneuploidy in proliferative and malignant lesions of the breast. Sectioning artifact that may result in nuclear truncation was controlled by establishing expected baseline frequencies for gain and loss in normal tissues from the same breast. Localization of chromosomal aberrations to proliferative breast disease lesions with concomitant retention of a normal chromosome complement in corresponding normal breast tissues indicates biologic significance of the results. The similarities of losses involving chromosomes 16, 17, and 18 in hyperplastic lesions and in malignant breast lesions suggest that some hyperplasias may be part of a sequence of progression to malignancy in breast cancer. Gains of chromosome 1 in both in situ and invasive carcinoma are consistent with reports of polysomy 1q as a common cytogenetic change in breast cancer. Its localization to advanced lesions suggests that this trisomy is probably not the initial cytogenetic change in breast cancer tumorigenesis.

Xenograft model of progressive human proliferative breast disease

BACKGROUND

Progression of proliferative breast disease has been associated with increased risk for development of invasive carcinoma. Cell lines have been developed to facilitate the study of this process. Human cell line MCF10A originated from spontaneous immortalization of breast epithelial cells obtained from a patient with fibrocystic disease, and cell lines MCF10AneoN and MCF10AneoT were created by stable transfection of these cells with the neomycin-resistance gene and either the HRAS gene or the mutated T-24 HRAS gene, respectively.

PURPOSE

Our goal was to develop an experimental model of progressive human proliferative breast disease.

METHODS

MCF10A, MCF10AneoN, and MCF10AneoT cells were injected subcutaneously into the dorsal flank of male nude/beige (C57/BALB/c nu/nu bg/bg) mice (12 mice for each cell type). These mice were examined periodically for formation and persistence or growth of palpable nodules. One mouse per group was killed 1 week after cell injection; thereafter, mice were observed as long as possible. Cells were recovered from palpable lesions by enzymatic dissociation of the excised lesions. Cells re-established in tissue culture from a week-14 tumor (MCF10AneoT.TG1) were injected into 12 male nude/beige mice. Southern blot hybridization analysis of the HRAS gene locus and cytogenetic analyses were performed.

RESULTS

Transplanted MCF10A and MCF10AneoN cells formed transient, small palpable nodules that regressed and disappeared during the 4th and 5th weeks. In 10 of the 12 mice, T-24 HRAS gene-transfected MCF10A cells (MCF10AneoT) formed small, flat nodules that persisted for at least 1 year. Three of these xenografts became carcinomas. One (removed 7 weeks after transplantation) was an undifferentiated carcinoma composed of polygonal cells with large, vesicular nuclei and numerous mitoses. The second (removed after 14 weeks) was an invasive squamous cell carcinoma. The third (removed after 56 weeks) was a moderately differentiated adenocarcinoma. Initially, xenografts of MCF10AneoT.TG1 cells showed intraductal proliferative changes; after 23 weeks, the lesions showed histologic features resembling those seen in atypical hyperplasia of the human breast, and later lesions showed characteristics of carcinoma in situ. The MCF10 lineage of cells of three MCF10AneoT.TG1 xenografts was confirmed by DNA fingerprinting and karyotype analysis.

CONCLUSIONS

MCF10AneoT and MCF10AneoT.TG1 comprise a transplantable xenograft model that produces a broad spectrum of human proliferative breast disease.

IMPLICATIONS

The reproducible establishment of representative stages in early breast cancer progression from the MCF10 model offers a new opportunity to analyze critical events of carcinogenesis and progression in breast cancer.

Extrachromosomal gene amplification in acute myeloid leukemia; characterization by metaphase analysis, comparative genomic hybridization, and semi-quantitative PCR

A case of acute myeloid leukemia (M-3) with complex karyotypic aberrations and double minute (dmin) chromosomes is presented. The patient had no history of prior exposure to mutagenic or carcinogenic agents or of other malignancies. She died from CNS involvement six weeks after the initial diagnosis. We used comparative genomic hybridization to identify the amplified sequences presumed to represent the dmin of the leukemic cells; the tumor/normal ratios indicated increased signal intensity at 8q24. This localization prompted investigation by semi-quantitative PCR that revealed amplification of the MYC oncogene. The extent of chromosome aberrations and the oncogene amplification, both linked with poor prognosis, may relate to the rapid course of this patient's disease.

Extensive genetic alterations in prostate cancer revealed by dual PCR and FISH analysis

The genetic alterations that underlie prostate tumorigenesis are assumed to comprise gain or loss of specific chromosomal regions, whole chromosomes, or sequence-specific mutations. Existing data have not demonstrated clear specificity of whole chromosome or regional chromosomal gain or loss that characterizes entire individual malignant lesions, or all malignant lesions, within a cancerous prostate. We have analyzed tissues from 13 patients for target sequences by using PCR and FISH techniques on paired malignant or prostatic intraepithelial neoplastic (PIN) and benign samples (usually from different areas of the same paraffin section). We exercised stringent histologic control over these samples by examining small (< 5 mm2), discrete regions of sectioned benign, malignant, and PIN tissue. The same histologic region was examined on serial sections by FISH and PCR analysis. The tissues were examined for numerical aberrations involving chromosomes 4 (as a control), 7, 8, 10, and the Y by FISH analysis, and for gain or loss of chromosome 7 and chromosomal arms 8p, 10q, and Yp by PCR analysis. The concurrent application of PCR and FISH to microdissected prostatic tissues yielded evidence of higher frequencies of genetic aberration in prostate cancers than those found with either method alone or by other approaches. These results indicate the power of simultaneous genetic assays that are closely linked to specific tumor histology.

Defining the extent and nature of cytogenetic events in prostatic adenocarcinoma: paraffin FISH vs. metaphase analysis

A comparative study of primary prostatic tumors utilizing conventional metaphase analysis of prostate tumor cultures and fluorescence in situ hybridization (FISH) analysis of paraffin-embedded tissue sections revealed significant differences in type and extent of cytogenetic aberrations. Clonal trisomy 7 was identified in two tumors by metaphase analysis of prostate cultures, but not confirmed in either case by FISH analysis. True gain of chromosome 8 was revealed by FISH analysis in malignant epithelium of four tumors but not in adjacent normal or hyperplastic glands. Neither gain nor loss of this chromosome was observed by metaphase analysis in any of the tumors. Significant monosomy and nullisomy of chromosome 10 was identified in one case by FISH, but no cells with gain or loss of chromosome 10 were observed by metaphase analysis. Significant loss of the Y chromosome was revealed in one tumor by FISH, but no cells with -Y were identified by metaphase analysis. Clonal loss of the Y chromosome was identified in two other tumors by metaphase analysis. Paraffin FISH analysis of these tumors revealed overall monosomy in both, although in one tumor there was extensive nodular loss of the Y chromosome. Paraffin FISH analysis permits identification of cytogenetic aberrations in areas identified as carcinoma (CaP), prostatic intraepithelial neoplasia (PIN), and benign prostatic hyperplasia (BPH). This technique appears more informative in defining the true extent and nature of cytogenetic aberrations in prostate cancer than metaphase analysis of prostate tumor cultures.

Chromosomal aberrations in two sporadic gastrinomas

Results of cell culture and cytogenetic analysis (standard and fluorescent in situ hybridization, FISH) of two sporadic gastrinomas are reported. Maintenance of hormonal activity was assessed by detection of gastrin levels during the first 3 months in culture. Case 1 showed clonal aberrations consisting of two marker chromosomes: marker 1 is a large metacentric chromosome and marker 2 is a small acrocentric chromosome. Case 2 showed a constitutional polymorphism with chromosome 15p+ and a clone in the tumor cell culture with trisomy for chromosome 3. To our knowledge, this is the first cytogenetic report of sporadic gastrinomas (Zollinger-Ellison syndrome).

Xenografts of primary human prostatic carcinoma

BACKGROUND

Prostatic carcinoma is both the most common invasive cancer and the second most common cause of cancer deaths in men in the United States. Before 1991, attempts to propagate prostatic carcinoma from primary tumors for periods longer than 3 months were unsuccessful in vivo and in vitro with rare exceptions. In 1991, we reported establishment of slowly growing tumors for six of 10 human primary prostatic carcinomas approximately 2-6 months after transplantation. However, none of the tumors were larger than 5 mm or serially transplantable.

PURPOSE

Our purpose in this study was to determine whether human primary prostatic carcinoma could be grown as serially transplantable xenografts.

METHODS

Cells from primary prostatic carcinomas obtained from transurethral prostatic resections or total prostatectomies in 20 patients were injected subcutaneously into male nude mice on the day of surgery. Sustained-release testosterone pellets were placed subcutaneously in the mice 2-24 days before transplantation of tumors and at intervals of 10-12 weeks. Serial transplantations in subsequent generations of mice were carried out by similar methods. Chromosome analysis was performed on six tumors.

RESULTS

Six of 20 primary prostatic carcinomas have grown sufficiently to permit serial transplantation into second mice; four have been documented histopathologically in the second mouse and serially transplanted into three or more successive mice. When a single primary tumor was injected into several mice by the same procedure, tumors failed to grow in some recipients but became serially transplantable in others. Growth of these tumors is slow and irregular, with frequent regressions. Short-term cultures of 10 tumors, eight of which were injected into mice in parallel, were initiated on the day of surgery; CWR31, which was successfully transplanted serially, exhibited only aberrant metaphases and showed clonal, chromosomal changes in culture. Including CWR31, three of the six tumors for which chromosomal analysis was successful contained clonal aberrations. Preliminary studies of SCID (severe combined immunodeficient) mice suggest that they are not superior to nude mice for establishment of serially transplantable prostatic carcinoma xenografts.

CONCLUSIONS

A proportion of human primary prostatic carcinomas can be grown as xenografts. Four new serially transplantable xenografts (CWR21, CWR31, CWR91, and CWR22) are currently propagated in our laboratory, a resource that was not previously available.

IMPLICATIONS

Our experience suggests that the most important factor in serial transplantation is the collaboration of urologists and pathologists in expediting placement of the tumor in cold saline, examination of the frozen section, and transplantation.

Complementarity of interphase and metaphase chromosome analysis in human renal tumors

Fluorescence in situ hybridization (FISH) was used as a complement to earlier cytogenetic studies of human renal tumors. Chromosome-specific para-centromeric probes were applied to cells disaggregated from tissue blocks of tumors, fresh samples from which had yielded cytogenetic results after short-term culture. Cells were dissociated from thick sections of paraffin-embedded, formalin-fixed tissues. Biotin-labeled probes specific for chromosomes 1, 3, 7, 11, 12, 15, 17, and the Y chromosome were applied in individual cases and were detected by fluorescence. Probes for chromosomes 1, 7, and 17 yielded clean signals with disomic control frequencies near 90%, and 97% of controls showed a single bright spot for the Y chromosome. The 9 cases selected all provided ample numbers of dissociated cells which were hybridized successfully, although some chromosomal signals were poor in individual cases. Abnormal copy numbers of chromosomes 1 and/or 17, not identified in culture, were observed in 7 cases. Trisomy 7 observed in culture was substantiated by FISH on the original tissues, as was loss of the Y, in each of 4 cases, respectively. Our results include limited validation of culture cytogenetics, evidence of selection in culture of tumor subpopulations, and demonstration that interphase cytogenetics by FISH is applicable to archival tissue blocks after prolonged periods of storage. Conditions of culture before harvest and inherent heterogeneity within tumors permit selection for nonrepresentative subgroups within tumors and emphasize the need for multiple approaches to evaluation.

Immunocytochemical characterization of male breast cancer

Biologic properties of breast cancer in men that might reflect alterations in pathogenesis from the disease in women were examined. We studied 22 tumors from males, 18 invasive carcinomas, three of which were papillary, and three in situ tumors of which one was papillary, and one papilloma. Our data support the previously reported high incidence of papillary carcinoma in men. Estrogen receptor status and the expression of cancer-associated antigens recognized by antibodies DF3, B73.2, SP-1, and c-erbB-2 were compared to matched tumors from females. Immunocytochemistry was performed on formalin-fixed, paraffin-embedded sections using standard avidin-biotin techniques; anti-PSA was used to exclude the possibility of metatastic prostate cancer, and 12 cases of gynecomastia were included as nonmalignant controls. The incidence of estrogen receptor positivity was higher in tumors from males (73%) than from females (54%), as has been reported previously. The range of expression of all breast cancer antigens tested in male tumors was similar to that observed in females, but some interesting differences were noted. With the exception of the anti-mucin DF3, all the antibodies reacted only with neoplastic tissues. Expression of the oncoprotein c-erbB-2 was lower (17%) in males than in females (33%), despite the preponderance in men of the large-cell type carcinomas that have been associated with c-erbB-2 expression. Unexpectedly, the pregnancy-associated hormone detected by SP-1 was expressed in 33% of tumors from males and, in contrast to females, was found in less differentiated tumors.

Genetic markers as prognostic indicators in breast cancer

BACKGROUND

Identifying markers that have the potential to predict tumor behavior is important in breast cancer because of the variability in clinical disease progression. Genetic alterations in tumors may appear as changes in total DNA content, individual chromosomes, single genes, or gene expression. Alteration in DNA content is an imprecise but accessible measurement of the genome. Diploid tumors have been associated with a better clinical outcome, and increased ploidy correlates with other indicators of poor prognosis. Concurrent analysis of DNA content with markers of genetic expression is feasible (e.g., myc oncogene) and may increase its prognostic power. Chromosomal studies could provide a more precise tool for localizing genetic damage, but there is little cytogenetic information about primary breast cancers, no convincing evidence has emerged to target locations in the karyotype that appear specifically altered, and many primary and cultured breast cancers contain cells that appear chromosomally normal. Attempts to define molecular markers have used probes of different chromosomal sites, some chosen because of logical associations with hormonal activity, known oncogenes, or tumor-suppressor genes, and some by chance. Currently, to the authors' knowledge, none has shown uniform changes by mutation, loss, or overexpression in all breast cancers, although a remarkable number of loci are altered to some extent. These lesions must be associated with particular disease subsets or, retrospectively, with differential survival if they are to have prognostic value.

METHODS

The authors examined several loci (ERBB2, INT2, MUC1) for gene amplification or loss of heterozygosity by Southern blotting and for gene expression by immunohistochemistry in breast tumors from patient groups selected by survival.

RESULTS AND CONCLUSIONS

A retrospective series showed gene amplification at the erbB2 locus in 22% of rapidly recurrent (RR) tumors and 13% of tumors from long-term tumor-free survivors (LTS), but the difference was not statistically significant (P = 0.18). The erbB2 product was displayed histochemically with equal frequency between those with RR tumors and LTS patients. Moreover, the correlation was poor between different analytic measures on the same tumors. This result was tested using a prospective study of erbB2 to correlate DNA analysis with western blot findings and frozen and fixed histochemical results. Another oncogene, int2, showed significant correlation between amplification and recurrence; 16% of RR tumors showing genetic amplification (P = 0.02). Loci on other chromosomes, 1 (muc1) and 17 (cmm86), also are being investigated in groups selected for differences in survival.