Retinoblastoma and p53 gene expression related to relapse and survival in human breast cancer: an immunohistochemical study

p53 and Breast Cancer

Inactivation of the p53 tumor suppressor gene is one of the commonest genetic changes identified in human breast cancer. In this review, the structure and function of the p53 gene and its protein products will be discussed, with particular reference to p53 alterations that contribute to carcinogenesis. The frequency and pattern of p53 alterations in breast cancer will be outlined, laboratory methods for their detection briefly summarized, and the potential use of p53 as a prognostic and predictive marker discussed.

RB family members as predictive and prognostic factors in human cancer

The retinoblastoma family members--pRb, pRb2/p130 and p107--are tumor suppressor genes involved in controlling four major cellular processes: growth arrest, apoptosis, differentiation and angiogenesis. Molecular genetic studies have identified abnormalities of these tumor suppressor genes in a large proportion of human cancers. These genetic alterations have emerged as significant factors in the pathogenesis and progression of many types of tumors and are therefore likely to provide relevant information to assess risk in cancer patients. There is a pressing clinical need to identify prognostic and predictive factors for patients with cancer, because there is an undeniable importance in being able to determine which patients will have a favorable outcome without further therapy (prognostic factor) and which will need some additional treatment (predictive factor). This review examines the predictive and/or prognostic role of each retinoblastoma family member in human cancer.

Cyclopedic protein expression analysis of cultured canine mammary gland adenocarcinoma cells from six tumours

We characterised cultured canine mammary gland adenocarcinoma cells by exhaustive step protein expression analysis to identify factors associated with tumour progression or metastasis of canine mammary gland tumour. Cultured adenocarcinoma cells derived from a total of 3 primary and 3 metastatic lesions from 3 dogs (CHMp/m, CIPp/m and CNMp/m, where CHM, CIP, and CNM indicate the 3 animals) were used in this study. The expression of 24 proteins reported to be related to tumourigenesis or malignancy of human breast cancers were examined by Western blot analysis using 24 antibodies. The expression of sialyl Lewis X [sLe(x)] was only observed in CHMm cells, which were derived from pleural effusion. This expression was further confirmed by immunohistochemistry. The levels of some factors, such as 14-3-3sigma, cyclinD1 and Rb, differed among cells or between the primary and metastatic cells in the pair. Though the difference in their expression was not consistent within the cells from primary and metastatic origin, this characterisation should provide useful information for further molecular analysis of these cultured cells. Since some of the factors, such as sLe(x), 14-3-3sigma, cyclinD1 and Rb, showed different levels of expression in the pair, these cultured cells might be meaningful tools for clarification of distant metastasis in canine mammary gland tumours.

Correlations of cell cycle regulators (p53, p21, pRb and mdm2) and c-erbB-2 with biological markers of proliferation and overall survival in breast cancer

AIM

The biological impact of cell cycle regulatory proteins on breast cancer progression is widely recognised, although mostly unclear. The aim of this preliminary study was to investigate the correlations of several cell cycle modulators (p53, p21, pRb, and mdm2) and c-erbB-2 expression with cell proliferation markers (S-phase fraction [SPF] and Ki-67) and overall survival in breast cancer.

METHODS

The series comprised 50 women with stage I-II invasive ductal breast carcinoma (median follow-up 87 months), who were selected for their tumour proliferative characteristics (15 low, 15 high, and 20 intermediate proliferative tumours). Tumour differentiation was assessed following the Nottingham grading criteria. Cell cycle regulators, oestrogen receptor status, and Ki-67 index were analysed by immunohistochemistry on paraffin embedded material (cut-offs 10%). c-erbB-2 was evaluated according to a standardised immunohistochemical assay and borderline cases were confirmed by FISH analysis. Ploidy and SPF were determined by DNA flow cytometry on frozen samples. Chi-square test and Fisher's exact test were applied to analyse the statistical significance of data.

RESULTS

Positive immunostaining was observed in nine (18%) p53+, 30 (60%) p21+, 13 (26%) pRb+, and one (2%) mdm2+ cases. c-erbB-2 expression was considered positive in 11 (22%) cases. In the subset of patients dead of the disease, a high incidence of c-erbB-2 over-expression (7/10, 70%) was verified. In general, no significant correlations among cell cycle regulators or between the latter and histopathological or proliferative characteristics were found. Only the p53-/p21+ phenotype significantly correlated with low SPF (p=0.048), and p21 positivity showed a trend to be associated with low SPF (p=0.083). No statistically significant correlations between cell cycle inhibitors and clinical outcome were found. On the contrary, c-erbB-2 over-expression showed significant correlations with DNA aneuploidy (p<0.001), high SPF (p<0.001), high tumour grading (p=0.008), lack of oestrogen receptors (p=0.036), and poor overall survival (p<0.001).

CONCLUSIONS

The results seem to indicate the lack of correlations of cell cycle regulatory proteins with cell proliferation markers and overall survival in breast cancer, in contrast to c-erbB-2 over-expression which was found to be associated with increased proliferation rate and worse prognosis.

Expression of c-erbB-2 and p53 in Breast Carcinoma Patients: Comparison with Traditional Prognostic Factors and Survival

We aimed to determine the correlations between standard clinicopathological factors and expression of c-erbB-2 and p53 proteins, and to investigate the significance of these variables in relapse and disease-free survival (DFS) in breast carcinoma patients. Data from 200 patients who had undergone mastectomy for breast carcinoma were evaluated. Significant correlations were found between c-erbB-2 positivity and high histological grade (grade 3) tumour, p53 positivity and high grade tumour, and age < 60 years and oestrogen receptor negativity. Twenty-six patients (13%) developed a recurrence. Disease relapse was more frequent in patients who had axillary lymph node (ALN) metastasis, high grade tumour, c-erbB-2 positivity and p53 positivity; these variables were also associated with a shorter DFS. The effects of ALN metastasis and p53 positivity were significant. In conclusion, ALN metastasis and p53 positivity were important factors for predicting disease relapse in mastectomy-treated breast carcinoma patients; other clinicopathological criteria and c-erbB-2 positivity were not predictive.

Prognostic implication of p53 protein expression in relation to nuclear pleomorphism and the MIB-1 counts in breast cancer

BACKGROUND

A close correlation of the p53 protein expression to nuclear pleomorphism and proliferative activity in breast cancer has been reported. The prognostic implications of p53 protein expression, however, in relation to nuclear pleomorphism and proliferative activity in breast cancer remain controversial.

PATIENTS AND METHODS

Nuclear pleomorphism and immunohistochemical reactivity for p53 protein and MIB-1 were evaluated on formalin-fixed paraffin-stored sections from 250 patients with breast cancer for whom the median follow-up duration was 6.4 years.

RESULTS

p53 protein expression was positive in 66 (26.4%) of 250 cases. Nuclear pleomorphism was grade I or II in 169 (67.6%) cases and grade III in 81(32.4%)cases. The MIB-1 counts were more than 10% in 102 (40.8%) cases and less than 10% in 148 (59.2%) cases. There was a close correlation between p53 protein expression and nuclear pleomorphism (p<0.0001) and between p53 protein expression and MIB-1 counts (p<0.0001). Univariate analyses showed the 66 cases with positive p53 protein expression to have a significantly (p=0.0284) worse disease free survival (DFS) than the 184 cases with negative p53 protein expression. A multivariate analysis, however, on the variables including all of p53 protein expression, nuclear pleomorphism and MIB-1 counts indicated the MIB-1 counts (p=0.0041) as well as the lymph node status to be independently significant factors for DFS, while neither p53 protein expression nor nuclear pleomorphism were independently significant factors for DFS.

CONCLUSION

The present study demonstrated that the p53 protein expression, nuclear pleomorphism and MIB-1 counts all demonstrated prognostic significance for breast cancer, while the most significant prognostic indicator among these three biological parameters was the MIB-1 counts.

Molecular evolutionary patterns in breast cancer

Geno-phenotypic patterns of pre-invasive and invasive lobular breast cancers and infiltrating ductal carcinomas of low, intermediate, and high grade are reviewed. One of the main differences between lobular breast cancers and ductal carcinomas is the presence of inactivating E-cadherin gene mutations in lobular breast cancers. In many other respects, lobular breast cancers and low-grade ductal carcinomas exhibit similar geno-phenotypic profiles. The development of p53 dysfunction may be a hallmark of infiltrating ductal cancers of intermediate and high grade. Sequential Her-2/neu and ras abnormalities define a subset of aggressive high-grade tumors, and the development of Rb dysfunction may define a separate subset of aggressive ductal cancers. Based on these observations, a branching molecular evolutionary model for the development and progression of breast cancer is proposed.

Incidence of P53 and K-ras alterations in ovarian mucinous and serous tumors

Clarification of the pathogenic relationships existing among ovarian cystadenomas, tumors of low malignant potential (LMP) and various adenocarcinoma types, a series of 29 mucinous and 19 serous ovarian tumors including adenomas, LMP tumors and adenocarcinomas were examined. P53 protein was detected by the streptavidin-biotin method and point mutation of K-ras codon 12 was detected by polymerase chain reaction-restriction fragment length polymorphism analysis. P53 overexpression was observed more frequently in serous adenocarcinomas (5/8, 63%) than in mucinous adenocarcinomas (2/9, 22%) and was correlated with the malignant potential of serous tumors. Furthermore, the proportion of P53-positive cells was significantly higher in serous adenocarcinomas than in mucinous adenocarcinomas. P53 overexpression may therefore be closely related to the early events of carcinogenesis in serous tumors. Although mutation of the K-ras oncogene appears to be an important event in the early tumorigenesis of mucinous tumors, mutation of the K-ras oncogene in serous tumors may be dependent on morphology. Different complex pathways of oncogene and/or tumor suppressor gene abnormalities may be involved in the development of mucinous and serous adenocarcinomas.

Prognostic and predictive value of p53 and p21 in breast cancer

The prognostic and predictive value of p53 has been extensively studied in breast cancer. p53 serves a multifunctional role as a transcriptional regulator, genomic stabilizer, inhibitor of cell cycle progression, facilitator of apoptosis, and also perhaps an inhibitor of angiogenesis. Abrogation of its function should therefore lead to a more aggressive breast cancer phenotype and a worse clinical outcome, and indeed the preponderance of studies confirm this, with the risk of recurrence and death increasing by 50% or more if p53 is abnormal. Lack of unanimity of results may be due to differences in technique, study design, or population, as well as the subjectivity inherent in some approaches; however, the complexity and random nature of genomic change present in cancer cells may well also contribute to the lack of unanimity. Because many anticancer agents may exert a therapeutic effect through genomic damage and subsequent triggering of apoptosis, and because p53 can respond to genomic damage and facilitate apoptosis, it can be hypothesized that an intact p53 would predict sensitivity to therapy. Present data in breast cancer, however, does not clearly indicate that this is the case. There are several potential explanations. Study designs to accurately test the predictive value of a molecular marker are more exacting and difficult to achieve than prognostic studies. There may also be multiple alternative pathways, not involving p53, that play a part in determining the therapeutic effect of a treatment. The prognostic value of a downstream effector of p53 has also been assessed, though less extensively. p21 is transcriptionally upregulated by p53 and is an inhibitor of cyclin-dependent kinases and thus of cell cycle progression. Higher levels of p21 might indicate a more indolent type of breast cancer. However, data from a number of clinical studies is very conflicting, and at present p21 is not a promising prognostic factor in breast cancer.

Retinoblastoma (RB1) gene product expression in breast carcinoma. Correlation with Ki-67 growth fraction and biopathological profile

AIMS

To investigate the expression of retinoblastoma protein (pRb) in invasive breast tumours and compare its expression with the major biopathological prognostic indicators to identify more aggressive subgroups.

MATERIAL

Archival paraffin embedded tissues from 153 consecutive primary breast carcinomas.

METHODS

pRb, Ki-67, and oestrogen receptor/progesterone receptor proteins were identified by immunohistochemistry and score values were recorded by image cytometric analysis; p53 and EGFr expression was also evaluated.

RESULTS

pRb scores correlated strongly with proliferation activity as determined by Ki-67 staining. Positive relations were also observed between pRb scores, tumour size, nuclear and histological grade, and oestrogen receptor/progesterone receptor content, while abnormal p53 accumulation was not associated with pRb expression. Among the high proliferating carcinomas it was possible to identify 13 cases with loss of pRb expression.

CONCLUSIONS

pRb expression paralleled proliferative activity in the majority of breast carcinomas examined, suggesting that in these cases the protein behaves normally in regulating the cell cycle. Conversely in cases with loss of pRb immunostaining, the combined expression of specific highly aggressive factors (EGFr and p53 expression, oestrogen receptor/progesterone receptor negative status, and high K67) seems to characterise a more aggressive phenotype showing growth advantage and cellular "progression" rather than significant nodal involvement.

Expression of metastasis-associated genes h-mts1 (S100A4) and nm23 in carcinoma of breast is related to disease progression

The murine 18A2/mts1 and its human homolog h-mts1 (S100A4), encoding a Ca2+-binding protein belonging to the S-100 family, are associated with high invasive and metastatic potentials of murine tumors, human tumor cell lines in vitro, and human tumors growing as xenografts. The nm23 is a putative metastasis-suppressor gene whose expression has been found to correlate inversely with the metastatic potential of some forms of human cancer. The products of both human genes alter cytoskeletal dynamics, with antagonistic effects. In view of the equivocal association of nm23 with the metastatic potential of human cancer, we suspected that the relative expression of h-mts1 and nm23 might reflect tumor progression more accurately than either of them alone. We describe here the expression of these genes in infiltrating ductal carcinomas of the breast and show that high h-mts1 expression is associated with metastatic spread to the regional lymph nodes. The expression of nm23 on its own did not show a statistically significant inverse correlation with nodal spread. However, the expression status of the two genes, taken together, correlated strongly with the occurrence of nodal metastases. Breast cancers with no detectable expression of h-mts1 were found to be estrogen and progesterone receptor positive. Expression of h-mts1 was not related to tumor differentiation. The clinical data, together with the state of expression of steroid receptors and the expression levels of h-mts1 and nm23 genes, were analyzed using artificial neural networks for accuracy in predicting nodal spread of the carcinomas. These analyses support the conclusion that, overall, h-mts1 expression appears to be associated with and indicative of more aggressive disease. Complemented with nm23, h-mts1 could provide a powerful marker of breast cancer prognosis.

Retinoblastoma and p16 proteins in mammary carcinoma: their relationship to cyclin D1 and histopathological parameters

The cell cycle-associated retinoblastoma protein (pRb) and p16 protein were demonstrated using immuno-histochemistry on paraffin sections from 192 cases of invasive breast carcinoma. Abnormal expression of pRb was defined as negative staining and was seen in 17% of tumours. Such abnormal expression was significantly more frequent in tumours with negative oestrogen receptor (ER) status. There was also a trend for tumours which were negative for pRb to be grade III ductal carcinomas. There was no association between p16 staining and any histopathological parameter, though, surprisingly, log-rank analysis showed that strong staining was associated with a poor outcome. There was a significant inverse relationship between pRb and p16 expression and a significant positive association between pRb and cyclin D1. In a Cox multivariate analysis, which included cyclin D1, neither pRb nor p16 was an independent predictor of patient outcome.

Expression of p16INK4 and retinoblastoma protein Rb in vulvar lesions of Chinese women

The protein products of the two tumor suppressor genes located on 9p and 13p, p16INK4 and Rb, respectively, play an important role in regulation of the cell cycle and are implicated in tumorigenesis. We examined 49 cases of benign vulvar lesions, vulvar intraepithelial neoplasia (VIN), and squamous cell carcinoma with immunohistochemical staining to determine expression of p16INK4 and Rb. All and 86% of benign lesions expressed Rb and p16INK4, respectively; 40% each of VIN I and VIN III expressed p16INK4 and Rb, respectively; and 37 and 68% of squamous cell carcinomas expressed p16INK4 and Rb, respectively. The combination of the lack of p16INK4 and/or Rb expression increased from benign lesions (14.3%), through VIN I (60%) and VIN III (60%), to invasive squamous cell carcinoma (72%), thus supporting the postulation that alterations in p16INK4 or Rb could be significant events in progression of disease. The loss of Rb expression also increased from stage I carcinoma (16.7%) through stage II (26.7%) and III (44.4%), to IV (50%), suggesting that Rb may play an important role in tumor progression. A larger study on VIN lesions and genetic coding is suggested to further investigate the role of p16INK4, Rb, and other factors in tumorigenesis and progression of vulvar cancers.

The cell cycle in breast cancer

Breast cancer is a heterogeneous disease regarding morphology, invasive behavior, metastatic capacity, hormone receptor expression and clinical outcome. For prediction of prognosis, tumor cell kinetics is an important feature, traditionally evaluated by estimation of cell growth-associated parameters such as mitotic index, S-phase fraction and expression of proliferation coupled proteins, for example proliferating cell nuclear antigen (PCNA) and Ki-67 antigen. Recent data indicate that deregulation of the cell cycle can occur at different levels in cancer and that the "deregulation pattern" can be of clinical significance. In the present overview we give a short description of approaches used for cell proliferation assessments, whereafter more recent data on cell cycle deregulation are discussed. Alterations of importance in breast cancer include overexpression of cyclins D1 and E, down-regulation of cyclin-dependent kinase inhibitors, such as p16, and inactivation of the retinoblastoma and p53 tumor suppressor proteins.

p53 expression is of independent predictive value in lymph node-negative breast carcinoma

The aim of this study was to evaluate p53 expression, determined by immunohistochemistry, in 151 infiltrating ductal breast carcinomas with negative axillary lymph nodes, and to determine whether p53 can be considered as an independent prognostic value for overall and disease-free survival. A monoclonal antibody (DO-7) that reacts with an epitope on the N terminal portion of the human protein p53 was used to detect p53 in paraffin-embedded sections, utilising a standard avidin-biotin-peroxidase complex (ABC) technique with a microwave oven antigen retrieval. Overexpression of p53 (more than 50% of stained cells) was found in 45 cases (30%). Forty-five cases were negative and occasionally or moderately stained cells were present in 61 cases. p53 protein overexpression was significantly associated with high histological grade and tumour necrosis, high MIB-1 value (MIB-1 > 30%) and negative oestrogen receptor status. Univariate analysis (log-rank) showed a shorter overall survival (P = 0.003) in patients with high tumour p53 positivity. This statistical significance was also seen on multivariate analysis (Cox's logistic regression, P = 0.004). p53 protein overexpression is an independent prognostic marker in node-negative breast carcinoma for overall survival and should be used with other prognostic factors.

Cyclin D1 and retinoblastoma gene expression in human breast carcinoma: correlation with tumour proliferation and oestrogen receptor status

Cyclin D1 (CCND1) and retinoblastoma (Rb) genes are cell cycle regulators which are altered in some breast carcinomas. However, the possible cooperation between CCND1 and Rb, as well as the influence and coincidence of their abnormalities in the proliferative capacity of mammary carcinoma cells in vivo, is still unknown. In order to assess both the significance of the CCND1 gene and Rb alterations in breast carcinomas and their relationship with the proliferative capacity of the tumours and other clinico-pathological factors, CCND1 mRNA expression was studied in 46 cases of primary breast carcinomas and matched normal tissue, 45 of which were also studied immunohistochemically, Rb expression was analysed in the same cases by immunohistochemistry, whereas the proliferative activity of the carcinoma was evaluated by flow cytometry. CCND1 mRNA was overexpressed in 19 tumours (41 per cent). Sixteen cases showed diffuse immunohistochemical expression, ten carcinomas had few positive cells, and 19 were absolutely negative. CCND1 mRNA and protein overexpression was associated with oestrogen receptor (ER) expression by the tumour. Interestingly, lack of ER expression was associated with a decreased CCND1 mRNA signal in non-overexpressed tumours. No association was observed between CCND1 mRNA or protein overexpression and tumour proliferation or other clinico-pathological parameters. Loss of Rb expression was observed in 26 per cent of the tumours. This abnormality was significantly associated with increased mean S-phase (P = 0.017) and decreased CCND1 mRNA expression in non-overexpressed tumours, supporting in vivo the postulated regulatory loop between Rb and CCND1 in vitro. We conclude that CCND1 up-regulation is not associated with increased proliferative activity in breast carcinomas, whereas its expression might be regulated in vivo by hormones and Rb. Loss of Rb expression is significantly associated with an increased proliferation of tumour cells, suggesting an important role in the progression of a subset of breast carcinomas, regardless of CCND1 abnormalities.

The pathological and biological nature of screen-detected breast carcinomas: a morphological and immunohistochemical study

Traditional and immunohistochemical markers of prognosis were examined in 455 mammary carcinomas derived from breast cancer screening and compared with those of 277 carcinomas presenting symptomatically over the same period. Tumours detected by population screening under the U.K. National Health Service Programme do not differ from those detected by other screening projects, but compared with symptomatic cancers, screen-detected cancers are more likely to be in situ and if invasive, to be smaller, of lower grade, and to have invaded vessels, perineural spaces, and lymph nodes less frequently. Tubular and cribriform types are more often represented in screened patients. Immunohistochemical markers which have been proposed as being related to likely tumour behaviour (epidermal growth factor receptor, c-erbB-2 protein, oestrogen and progesterone receptors, cathepsin D, p53, and retinoblastoma protein) do not distinguish screen-detected from 'clinical' cancers. It is concluded that cancers diagnosed at screening do not differ biologically from those presenting clinically, but are the same lesions detected at an earlier stage of their natural history.

Analysis of phosphorylation of pRB and its regulatory proteins in breast cancer

AIM

In order to study the role of retinoblastoma protein (pRB) in breast cancer, the phosphorylation of pRB and the expression of its related proteins-such as cyclin E, cyclin dependent kinase 2 (Cdk2), and p21/Cdk interacting protein 1 (Cip1)-were examined in 30 breast cancers in which pRB overexpression was confirmed immunohistochemically.

METHODS

The phosphorylation of pRB for 30 tumours was investigated with western blotting. The expression of pRB, Cdk2/Cdc2, cyclin E, and p21/Cip1 was identified by immunohistochemistry and western blotting.

RESULTS

The expression of pRB was confirmed in 52 of 70 tumours (74%) by immunostaining. Western blotting for pRB showed that 25 of 30 representative cancers (83%) were underphosphorylated, while only five tumours showed the hyperphosphorylated form of pRB. However, cyclin E and Cdk2-which promote phosphorylation of pRB-were expressed in all tumours. On the other hand p21/Cip1, a Cdk2 inhibitor, was expressed in 18 of 25 tumours with underphosphorylated pRB, while four of the five tumours with hyperphosphorylated pRB showed no expression of p21/Cip1. Examination of the relation between pRB phosphorylation and clinicopathological variables showed that the underphosphorylated group was characterised by low risk of lymph node metastasis (p < 0.01).

CONCLUSIONS

The phosphorylation of pRB appears to be regulated mainly by p21/Cip1 through the suppression of cyclin E and Cdk2 in breast cancer. The underphosphorylated form of pRB may be useful as a prognostic factor.

The detection of nodal metastasis in breast cancer using neural network techniques

Identification and treatment of involved axillary lymph nodes is important in the planning of strategies for adjuvant treatments of breast cancer. With the advent of the National Health Service Screening Programme, an increasing number of women with the disease are detected at an early stage, when the lymph nodes are not involved. In whom, therefore, is it necessary to carry out a formal axillary dissection? Are there accurate surrogates for lymph node involvement in the form of tumour markers or characteristics? This study, carried out on over 81 patients, examines the use of neural networks to predict the involvement of lymph nodes using readily available clinical and pathological data and also more specialized markers of possible prognostic significance. The study shows that neural networks are capable of providing strong indicators as to lymph node status using only basic measurements of the primary breast tumour. However, accuracy can be improved by the addition of less common markers.

Retinoblastoma protein in human breast carcinoma: immunohistochemical study using a new monoclonal antibody effective on routinely processed tissues

Cyclic phosphorylation/dephosphorylation of the retinoblastoma gene product (pRB) has been found to play a central role in the progression of the normal cell cycle, through modulation of the activity of the E2F family of transcription factors. Mutations of the retinoblastoma gene have been described in a wide variety of human malignancies including carcinomas of the breast. The present investigation reports the production and application of a new monoclonal antibody in an immunohistochemical study of pRB expression in 233 primary breast carcinomas, allowing an assessment of the contribution made by this tumour suppressor gene to tumour development and progression. Overall, there was loss of pRB expression in 21 per cent of breast tumours. Although high-grade tumours were found to lack detectable pRB more frequently than low-grade tumours, the difference did not prove statistically significant. In addition, pRB immunostaining was not related significantly to relapse or survival. No significant correlations were observed between apparent loss of pRB and tumour size, parity, patient lymph-node status, p53, c-erbB-2, c-jun, EGFR or steroid hormone receptor expression. Preliminary findings, however, did suggest a relationship between pRB expression and response to endocrine therapy.

Immunohistochemical study of Cell Cycle Modulators in G(1)-S Transition in Clinical Breast Cancer Tissue

In the present study, we investigated immunolocalization of the modulators of G(1)-S transition by using monoclonal or polyclonal antibodies for each of the modulators in 65 cases of clinical breast cancer. Two prominent cyclin dependent kinase(cdk)-cyclin complexes, cdk4-cyclin D and cdk2-cyclin E, were proved to have different modes of mutual expression. cdk4-positive lesions were found to equal cyclin D-expressing lesions in 55 cases, while the former were more extensive than the latter in 9 cases. On the other hand, cyclin E expression was detected in all the cases examined and was more dominant than that of cdk2/cdc2 in as many as 40 cases whereas the reverse was seen in only 1 case. Interestingly, cdk4(P<0.01)and cyclin E(P<0.05)expressions showed an inverse relationship with the tumor size and the cancer stage. A similar tendency was also detected for two other positive modulators of G(1)-S transition, indicating that cell cycle progression must be regulated by the cancer itself once it has grown to a certain extent. p21, which has been regarded as a universal inhibitor of the cell cycle, was expressed in 43.1% of the cases examined and its immunoreactivity showed an inverse relationship with lymph node metastasis(P<0.05). It also tended to be absent more frequently in T3 or larger cancers and stage III cases. Moreover, two patients who died as a result of cancer and three patients with recurrence were all p21 negative, suggesting that p21 is prognosticably the most significant of all these modulators.

p53 protein as a prognostic indicator in breast carcinoma: a comparison of four antibodies for immunohistochemistry

We examined the reactivity of four p53-specific monoclonal antibodies--PAb 1801, p53-BP-12, D07 and CM1--on sections of formalin-fixed tissue collected from 245 breast carcinomas. Immunodetection of p53 varied between 37.6% and 46.6%. The greatest variation was observed among lobular carcinomas and low-grade tumors in which immunodetection varied between 8.3% and 27.3%. In contrast, immunodetection of p53 in invasive ductal carcinomas was subject to a lower degree of variability with between 40.6% and 49.7% of these tumours proving to be positive. In general, we found antibodies PAb 1801 and DO7 to be the most effective in immunolocalising p53. Immunodetection of p53 with each of the four antibodies was found to correlate strongly with tumour grade. In survival analysis, the results gained using antibody PAb 1801 proved to be of greatest statistical significance and to provide the strongest index of prognosis. A significant relationship was observed between immunodetection of p53 with each of the four antibodies and poor responsiveness to endocrine therapy. In addition, relationships were also observed between p53 immunostaining and tumour oestrogen receptor (ER) status as well as c-jun expression. We observed no correlation between abnormalities of the p53 and the Rb gene products or between elevated c-erbB-2 or epidermal growth factor receptor (EGFR) expression and immunodetection of p53.

A flow cytometric study of c-erbB-3 expression in breast cancer

In order to assess the specificity of biotinylated anti-c-erbB-3 antibody, screening was performed on a series of tumour cell lines and lymphocytes. Staining was found to be consistent, with good reproducibility. Twenty-nine consecutive breast cancer samples were obtained from women treated with tamoxifen and undergoing elective mastectomy. Twenty-eight invasive ductal carcinomas and 1 DCIS were stained for c-erbB-3 expression: 2 were grade I (Bloom and Richardson), 15 grade II, and 11 grade III tumours, 1 being unclassified; 16 were axillary node positive and 10 node negative; in 2 cases no nodes were sampled. Tumours examined by flow cytometry were stained with cytokeratin FITC antibody and the cytokeratin-positive population gated. Using Mann-Whitney analysis no association was seen between c-erbB-3 expression and Bloom and Richardson grade or axillary node status. In the tumour samples c-erbB-3 expression was found to show as association with EGF-R (P = 0.021 r2 = 0.16), PgR (P = 0.02, r2 = 0.16), c-myc (P < 0.0001, r2 = 0.5), c-jun (P = 0.001, r2 = 0.4) and c-fos (P = 0.001, r2 = 0.5) but not with c-erbB-2 (P = 0.2, r2 = 0.06), ER (P = 0.4, r2 = 0.02) or p53 1801 (P = 0.05, r2 = 0.2). Expression of c-erbB-3 may not be an independent marker of prognosis, but it is associated with other markers of poor prognosis and early cellular events linked with aberrant growth and differentiation.

Expression of p53 protein has no independent prognostic value in breast cancer

A series of 392 female breast carcinomas was analysed immunohistochemically for expression of p53 protein with special emphasis on the role of p53 as an independent prognostic factor. Altogether, 54.8 per cent of the carcinomas expressed p53 protein, with the mean [standard error (SE)] fraction of positive nuclei being 17.1 per cent (1.2 per cent). Expression of p53 protein was independent of tumour metastasis at diagnosis, axillary lymph node status, tumour diameter, histological type, tubule formation, proportion of intraductal growth, margin formation, necrosis, DNA ploidy, and S-phase fraction. A high fraction of p53-positive nuclei was significantly related to patient age under 70 years, high grade, severe nuclear pleomorphism, dense infiltration of tumour by lymphocytes, high mitotic index, and high apoptotic index (for all, P < 0.05). Impaired survival probability in the entire cohort (P = 0.05) and in the axillary lymph node-positive (ANP) tumours (P = 0.015) was associated with a fraction of p53-positive nuclei less than 25 per cent, while in the axillary lymph node-negative (ANN) tumours, expression of p53 had no prognostic value. In multivariate analysis, independent prognostic predictors included axillary lymph node status, tumour diameter, and mitotic index. In the ANN tumours, tumour diameter, fraction of p53-positive nuclei, and tumour grade were independent prognostic factors, whereas in the ANP tumours, diameter and mitotic index were the two independent prognostic factors. The results suggest that abnormal expression of p53 protein is only a weak independent prognostic factor in female breast cancer.

P53 protein in 204 patients with primary breast carcinoma--immunohistochemical detection and clinical value as a prognostic factor

In a retrospective study, 204 formalin-fixed and paraffin-embedded biopsies of primary breast carcinomas were tested immunohistochemically for the expression of p53 protein (PAb 1801). 38% of the carcinomas were positive with respect to p53. The expression of p53 correlated significantly with the loss of tumor differentiation (P = 0.013), but not with menopausal status, patients' age, tumor size, axillary lymph node involvement or hormone receptor status. The influence of p53 expression on prognosis was evaluated in 197 patients (T1-4 N0-2 M0, median observation time 72 months). Detection of p53 protein was associated with a significantly longer disease-free survival in node-positive women (P = 0.03). However, p53 protein did not prove to be a prognostic factor in node-negative patients. The results demonstrate the prognostic value of p53 expression in breast cancer which appears to be limited to patients with node-positive tumors.

Aberrant p53 expression does not correlate with the prognosis in anaplastic astrocytoma

Mutations of the p53 tumor-suppressor gene, as determined by the immunohistochemistry of archival formalin-fixed specimens, have been correlated with the prognosis for patients with many different types of malignancy. Similar correlations have been shown in series including patients with all grades of astrocytoma. We hypothesized that this might be a clinically useful prognostic indicator for patients with a defined grade of astrocytoma, anaplastic astrocytoma. This series comprised 54 consecutive patients with biopsy-proven anaplastic astrocytoma treated at one institution. When the CM-1 antiserum was used for testing, 33 (61%) of the 54 biopsies exhibited positive nuclear staining for p53, indicating an abnormal accumulation of the protein. This staining was graded according to the number of positive cells per high-power field. Positive immunohistochemical staining for p53 in the tumor cell nuclei did not correlate with the patient's outcome. Significant correlates of improved patient survival were the presentation with epilepsy in the absence of a neurological deficit (P = 0.005) and the surgeon's performance of a macroscopically complete surgical resection of the tumor (P = 0.01).

Oncogene protein co-expression. Value of Ha-ras, c-myc, c-fos, and p53 as prognostic discriminants for breast carcinoma

OBJECTIVE

A refinement of prognostic variables using traditional pathologic markers integrated with oncogene proteins, enzymes, and hormonal factors may enhance the ability to predict for recurrence or survival in patients with mammary carcinoma. Although various oncogenes and oncogene products have been identified in human breast carcinoma, their relationship to disease outcome remains controversial.

METHODS

Using the monoclonal antibodies cS93.1, 9E1.0, F235-1.7.1, and PAb 1801 against each oncogene protein studied, the avidin-biotin complex immunoperoxidase method provided immunohistochemical staining of bound oncogene protein for c-fos, c-myc, Ha-ras, and p53, respectively. Analyses were made on archival pathology tissues of 85 breast cancer patients (stages I, IIA, and IIB). Forty patients (47%) had recurrence of disease; 45 remained free of local-regional or distant disease at mean follow-up of 48 months (range 6-180 months). Molecular biological data were merged with clinicopathologic demographics 1) to determine the frequency of single or co-expression of oncogenes in this patient population; 2) to evaluate the value of these molecular protein markers to predict probability of recurrence; and 3) to determine worth of the studied oncogenes to correlate with traditional clinical pathologic parameters and overall survival.

RESULTS

In this study, oncogene expression had statistical correlation for recurrence with increasing co-expression: one oncogene 17.2%, two oncogenes 56.3%, three or four oncogenes, 100% (p = 0.001). Increasing oncogene or co-oncogene expression correlated with statistically significant reduction in disease-free and overall survival; with no expression of oncogenes, disease-free survival was 30 (SE +/- 5.7) months and overall survival was 56.4 (SE +/- 4.57) months. With expression of three oncogenes, disease-free survival was 12 (SE +/- 1.23) months (p = 0.0018) and overall survival was 23.4 (SE +/- 3.38) months (p = 0.0025). In univariate Wilcoxon analysis, oncogene expression was the most significant variable to determine survival (p = 0.035); in multivariate analysis, age and oncogene co-expression each emerged as the most significant variables for overall survival. For the proportional hazards regression model, oncogene co-expression was significant (p = 0.0104, risk-ratio 1.914) and correlated with age and tumor size as significant variables. Ha-ras and c-fos both emerged as important individual oncogene proteins to affect survival (p = 0.0925, risk-ratio 3.517 and p = 0.025, risk-ratio 4.214, respectively). The proto-oncogene c-myc and the antitumor suppressor gene p53 did not have significant effects as individual oncogenes to influence survival.

CONCLUSIONS

Approximately one fifth of the breast cancer patients in this analysis (disease-free and recurrent) expressed only a single oncogene marker (c-fos, c-myc, Ha-ras, or p53); one quarter of patients with recurrent disease expressed only one oncogene protein. Single oncogene expression did not possess independent prognostic significance for prediction of recurrence. Further, p53 mutations did not function as independent correlates for prognosis. The co-expression of the studied proto-oncogenes (c-myc, Ha-ras) and the nuclear transcriptional protein (c-fos) functioned as a strong prognostic correlate for recurrence and survival; the effect of individual oncogenes to predict survival was greatest for Ha-ras and c-fos. Immediate or early co-expression of three oncogene proteins in neoplastic transformation endowed cells of invasive carcinoma with an aggressive phenotype. This aggressive phenotype was evident in a small percentage of the studied population (11%) and predicted adverse disease-free and overall survival. These findings suggest that oncogene co-expression possesses significant prognostic and potential therapeutic value; incorporation of this molecular technology into future prospective randomized trials is advisable.

Association between RB-1 gene alterations and factors of favourable prognosis in human breast cancer, without effect on survival

The retinoblastoma (RB) tumour suppressor gene has been associated not only with retinoblastoma but also with several other tumours like osteosarcoma, small cell lung carcinoma and prostate and breast cancer. We have studied the incidence of RB gene alterations in 96 primary breast tumours using Southern blotting techniques. The outcome has been related with patient and tumour characteristics, oncogene amplifications, p53 mutations and prognosis. RB gene alterations were found to occur more frequently in estrogen receptor (ER)-positive than in ER-negative tumours and less frequently in tumours with oncogene amplification than in tumours without oncogene amplification of HER2/neu, c-myc or 11q13. RB gene alteration was observed in tumours both with and without a p53 gene mutation. Data on 87 patients (mean age, 59.6 years; median follow-up, 108 months) and RB gene alterations revealed a significant association between the frequency of RB gene alterations and node-negative patients (p < 0.01) or smaller (< 2 cm) tumours (p < 0.01), but no relation with age, differentiation grade or (relapse-free) survival. Patients with and without RB gene alterations showed the same relapse-free and overall survival.

Expression of tumour-suppressor gene Rb, apoptosis-suppressing protein Bcl-2 and c-Myc have no independent prognostic value in renal adenocarcinoma

The expression of retinoblastoma (Rb), c-Myc and Bcl-2 proteins was studied by immunohistochemical methods in 104 cases of renal adenocarcinoma. One tumour was completely negative for Rb protein and altered expression pattern was detected in 36% of cases. A low fraction of Rb-positive nuclei was related to high grade (P = 0.016) and high mitotic index (P = 0.012). Twenty-eight per cent of the tumours expressed c-Myc in cancer cell nuclei and 87% showed cytoplasmic positivity. Cytoplasmic expression of c-Myc was related to high grade (P = 0.002), while nuclear expression of c-Myc was related to small tumour diameter (P = 0.034), low T category (P = 0.04), low mitotic index (P = 0.019) and expression of c-ErbB-2 (P = 0.0007). Overexpression of c-myc predicted favourable outcome in M0 tumours (P = 0.0157). Bcl-2 was expressed in 20% of tumours and it was related to small tumour size (P < 0.0001), low T category (P < 0.0001), lack of venous invasion (P = 0.008), node negativity (P = 0.015) and absence of metastasis (P = 0.017). In multivariate analysis the expression of Rb, Bcl-2 and c-Myc had no independent prognostic value over T category (P < 0.001), mitotic index (P = 0.008) and combined nuclear grade (P = 0.056).

Expression of proliferating cell nuclear antigen, Ki-67 antigen, estrogen receptor protein, and tumor suppressor p53 gene in cytologic samples of breast cancer: an immunochemical study with clinical, pathobiological, and histologic correlations

Sixty-six unselected breast cancers were analyzed in cytologic smears and histologic sections for the expression of Ki-67, proliferating cell nuclear antigen (PCNA), estrogen receptor protein (ERP), and p53 protein using a standard immunochemical method. The results, expressed as both positive cases and labelling index (LI), were compared with clinical and pathobiological variables. Ki-67 and PCNA immunostaining was seen in all cases, whereas ERP was detectable in 46/63 cases and p53 protein in 20/66 cases. The expression of these markers was generally lower in cytology than in histology, though the differences were not statistically significant. PCNA-LI and Ki-67-LI were closely correlated (P < 0.001), the mean PCNA:Ki-67 ratio being 0.92 +/- 0.57. Occasional discrepancies, however, were found. PCNA and Ki-67 expression was associated with an increase in histologic grade and a decrease in ERP content of tumors, whereas p53 was statistically associated with no clinical or pathobiological variables. The data suggest that proliferative activity and oncogene overexpression may be reliably evaluated in breast cancer by FNA cytology, though PCNA is not a suitable indicator for cell proliferation. The results do not resolve the issue as to whether immunostaining for p53 protein constitutes a dedifferentiation product of the tumor, or is a fundamental aspect of the malignant progression. Survival studies in a larger series of tumors are thus needed to elucidate this point.

Prognostic value of N-myc immunoreactivity in medullary thyroid carcinoma

BACKGROUND

The analysis of N-myc expression in some neuroendocrine tumors has been reported to provide prognostic information. To the authors' knowledge, no attempts have been made thus far to correlate N-myc expression with the clinical outcome of medullary thyroid carcinoma (MTC).

METHODS

N-myc gene product immunoreactivity was evaluated in 34 patients with MTC with long term follow-up, using the OA-11-803 polyclonal antiserum. The results were related to patient age and sex, sporadic or familial disease, tumor size, stage, growth rate (as determined by proliferating cell nuclear antigen [PCNA] immunostaining), and to clinical outcome.

RESULTS

Patients harboring tumors with greater than 10% neoplastic cells immunoreactive to the N-myc antiserum (58% of the cases investigated) had significantly greater tumor size (P = 0.031) than patients with fewer or no N-myc immunoreactive cells. Deregulated expression of N-myc protein in tumor cells was not due to gene amplification, as demonstrated by multiplex polymerase chain reaction (PCR). In univariate analysis, patients with more than 10% immunoreactive neoplastic cells showed a significantly shorter disease free survival than did the remaining patients (P = 0.002). Among the other clinicopathologic parameters evaluated, male sex (P = 0.039) and sporadic disease (P = 0.035) also were associated with shorter disease free survival. In multivariate analysis, N-myc immunoreactivity (P = 0.039) and male sex (p = 0.050) retained a significant correlation with poor prognosis.

CONCLUSIONS

Our results suggest that immunoreactivity to the N-myc antiserum, but not tumor growth fraction as evaluated by PCNA immunostaining, is a novel and useful adjunct to predict clinical behavior of MTC.

P53 protein expression in hepatoblastoma: an immunohistochemical investigation

Mutations of the p53 tumor suppressor gene with immunohistochemically detectable expression of p53 protein have been described in many different malignant tumors. In this study, 12 hepatoblastomas of various subtypes were investigated immunohistochemically with a monoclonal antibody for the expression of p53 protein. Immunoreactivity for p53 protein was found in both small cell tumors investigated and in embryonal areas in two out of eight tumors, but not fetal (eight tumors) or mesenchymal (four tumors) areas. The findings show that immunohistochemically detectable expression of p53 protein, which generally indicates mutation of the gene, may also be present in hepatoblastoma. The finding of p53 protein immunoreactivity in both of the small cell tumors but none of the fetal areas is consistent with a proposal in the literature concerning the histogenesis and differentiation of the various subtypes---that fetal hepatoblastoma is the most well-differentiated and small cell hepatoblastoma the least well-differentiated subtype.

Salivary duct carcinoma--a highly aggressive salivary gland tumour with overexpression of c-erbB-2

The clinicopathological and immunocytochemical features of nine cases of salivary duct carcinoma are described. This relatively rare tumour, which only recently has been widely recognized as a separate entity, is highly malignant and caused the death in eight of the patients. The tumour cells are arranged in cribriform and solid growth patterns, where the solid tumour nests frequently have comedo necrosis, and a fibrous, often sclerotic, stroma is present. The infiltrating desmoplasmic component and the diffuse invasive growth into adjacent adipose parotid tissue have similarities to ductal breast carcinoma. Immunocytochemical investigation of salivary duct carcinoma showed constant overexpression of c-erbB-2 as detected by membrane accentuation, and high proliferative activity as detected by nuclear positivity for MIB 1 (Ki-67). Changes in the expression of p53 and retinoblastoma gene product do not constitute a constant event in salivary duct carcinoma. A few of the tumours showed scattered cells with distinct nuclear positivity for both progesterone and oestrogen receptors. We emphasize that this highly malignant salivary gland tumour has a characteristic morphology, may not be as rare as previously considered, and that prompt and aggressive therapy is needed.

Quantitative analysis of mutant p53 protein in breast tumor cytosols and study of its association with other biochemical prognostic indicators in breast cancer

Breast tumors are thought to originate, grow, and metastasize in an environment which includes steroid hormone receptors, their cognate steroid ligands, and many gene products which are regulated by steroid hormone receptor-ligand complexes. In this paper we describe highly sensitive and quantitative immunofluorometric procedures for measuring three proteins that are candidate prognostic indicators in breast cancer, namely, the p53 tumor suppressor gene product, carcinoembryonic antigen (CEA), and prostate specific antigen (PSA). These proteins were quantified in over 950 cytosolic tumor extracts along with estrogen and progesterone receptors (ER, PR). Association analysis between all five biochemical parameters revealed strong negative associations between p53 and receptors and strong positive associations between CEA and receptors. Negative associations between p53 and CEA and between CEA and PSA were also found. These associations, not quantitatively studied in previous reports, are related to each other using a hypothetical model. The observed associations may further contribute to the understanding of the biology of breast tumors.

NDP-K/nm23 expression in human breast cancer in relation to relapse, survival, and other prognostic factors: an immunohistochemical study

The nm23 gene was originally identified by Steeg et al. by screening of cDNA libraries from murine melanoma cell lines of varying metastatic potential. An inverse relationship between metastatic potential and nm23 RNA and/or protein was found in four different metastatic model systems. It was proposed that nm23 may function as a suppressor gene for tumour metastasis. It has recently been found that the sequence of nm23 and NDP-kinase (NDP-K) is identical. Using an immunohistochemical technique and employing a polyclonal antibody to purified NDP-K A, we have determined NDP-K expression in a series of 197 breast carcinomas. One hundred and sixty (81.2 per cent) of these tumours were scored positive for NDP-K and 37 (18.8 per cent) scored negative. No relationship was found between NDP-K/nm23 expression and patient relapse or survival. Furthermore, no relationship was found between NDP-K/nm23 expression and a number of other prognostic factors including tumour grade, oestrogen receptor, progesterone receptor, and p53 expression. Our results contradict the hypothesis concerning the possible role of NDP-K/nm23 as a metastatic suppressor gene in human breast cancer, but further studies using antibodies specific for NDP-K/nm23 subtypes are clearly indicated.

Cellular oncogenes and suppressor genes as prognostic markers in cancer

Activation of cellular or c-oncogenes and loss of function of suppressor genes appears to be the key event in the formation of most human cancers. Altered forms of these genes or their protein products have the potential to provide a new generation of cancer markers. As cancer markers, the most useful application of c-oncogenes and suppressor genes so far, has been in providing prognostic information. The correlation of N-myc gene amplification with poor prognosis in neuroblastoma was one of the first examples of prognostic data supplied by a c-oncogene. Most, but not all investigators, find that either amplification or increased expression of c-erbB-2 gene correlates with poor prognosis in breast cancer. Other potential prognostic markers in breast cancer include amplification of the c-myc gene, and increased expression of both EGFR and p53 protein. Although c-oncogenes and suppressor genes have the potential to supply prognostic information in a broad range of cancers, many of the results are still preliminary with conflicting conclusions.

p53 accumulation in ovarian carcinomas and its prognostic implications

Intranuclear p53 accumulation is a common finding in many different human tumors and is associated with a worse prognosis in breast, colon, and lung carcinomas. We immunostained a series of common epithelial ovarian cancers to assess (1) the prevalence of p53 accumulation and its clinicopathologic correlations, and (2) its prognostic implications. The study population comprised 98 patients (83 with follow-up data). A variable degree of p53 immunoreactivity, strictly confined to the neoplastic cells, was detected in 54 tumors (55%). Among these tumors there were 10 low expressors (1% to 10% immunoreactive tumor cells), 16 moderate expressors (10% to 50% immunoreactive cells), and 28 high expressors (> 50% immunoreactive cells). The prevalence of p53 immunoreactivity did not show any association with the histologic type of the tumors or with the disease stage at presentation. p53 Accumulation, however, was significantly more prevalent among poorly differentiated tumors (P = .0059, by analysis of variance). Life table analysis demonstrated that patients with tumors showing moderate and high p53 expression had worse disease-free and adjusted lengths of survival (P = .0011 and P = .0025, respectively, by Mantel-Cox). The patients with "early stage" disease (stages I and II) and p53 accumulation showed a trend toward shorter length of survival, but this did not reach statistical significance. However, patients with "advanced stage" disease (stages III and IV) and moderate or high p53 accumulation had a poorer prognosis (P = .0154 and P = .0171, for disease-free and adjusted length of survival, respectively). These results suggest that p53 accumulation occurs more frequently in tumors with aggressive behavior and that p53 immunoreactivity may have a prognostic role in certain subsets of patients with ovarian carcinoma.

Prognostic value of p53 protein expression in breast carcinomas

A group of 196 ductal infiltrating carcinomas of the breast was examined immunohistochemically for p53. The purpose of this study was to show whether frozen and fixed tissues are equally adequate for detection of p53 and which antibodies should be used to have a prognostic value. Detection was superior on frozen to that on formalin-fixed tissues. It was not possible with any method to improve results on fixed tissues. Detection of p53 was different for each antibody: M 1801 detected 41 cases on frozen tissues, M-240 52 cases, M-421 28 cases. Using all the antisera, and the rabbit antiserum CM1, it was possible to detect 71 cases (36%). The percentage was the same in infiltrating lobular carcinomas but higher (94%) in medullary carcinomas. p53 was associated with high grade and ER-tumours. In formalin-fixed tissues, p53 had no prognostic value. In frozen tissues p53 was not an independent factor of prognosis. However, it was important in sorting out cases with bad prognosis in the ER-carcinomas and in the carcinomas without metastases. The prognostic value was different for each monoclonal antiserum. Positivity with M421 associated with negativity for M240, and positivity only for M1801 sorted out cases with a poor prognosis (67% and 50% deaths at 5 years).

The relation between p53 mutation and p53 immunostaining in non-melanoma skin cancer

Extensive study of the p53 gene has established its role as a tumour-suppressor gene, and the involvement of mutant p53 in a wide spectrum of human malignancy. Many mutations of p53 result in a protein product that is abnormally stable, so that it becomes readily detectable by immunocytochemistry. In contrast, under normal conditions, it has been considered that levels of wild-type p53 were too low to be detectable. Although positive immunocytochemistry has been used as a marker of mutation, recent evidence suggests that this assumption may not always be valid. We have carried out both PCR-sequencing of exons 5-8 of the p53 gene in 20 basal cell carcinomas (BCC), and immunocytochemistry of these tumours with the anti-p53 antibody DO7. Twenty cases of Bowen's disease, in which we had previously documented mutations, were also immunostained. We report a low rate of p53 mutation in the BCCs we examined (2/20), and a discrepancy between tumours with positive immunostaining and those with mutation in both Bowen's disease and BCC. Of eight tumours in which we detected mutation, only four were immunopositive: of 19 immunopositive samples, only four showed detectable mutation. We discuss the implications of our results for the use of positive immunostaining in clinical diagnosis, and the involvement of p53 in skin carcinogenesis.

p53 protein expression in breast cancer as related to histopathological characteristics and prognosis

Formalin-fixed, paraffin-embedded biopsies of 193 women with primary breast cancer followed-up for over 10 years were analysed immunohistochemically for the expression of p53 protein. Altogether, 58% (113/193) of the tumors were positive for p53 protein. Over-expression of p53 was associated with the ductal type, high-grade tumors, dense stromal inflammatory cell infiltrate, high S-phase fraction, high mitotic frequency and high values of the nuclear factors. In univariate analysis, intense p53 over-expression predicted a poor outcome, whereas a short recurrence-free survival (RFS) was related to p53 negativity. In axillary lymph-node-negative (ANN) tumors, p53 negativity was related to short RFS, and in axillary lymph-node-positive (ANP) tumors this inverse relationship was statistically significant. In Cox's analysis, p53 protein over-expression had no independent prognostic value comparable with the well-established prognostic factors. However, p53 protein accumulation was an independent indicator of long RFS in the entire cohort, in ANP tumors and in rapidly proliferating tumors. The results indicate a dual role for p53 protein over-expression in breast cancer prognosis. The low survival probability associated with intensively p53-positive tumors is probably related to rapid cancer-cell proliferation, whereas the long RFS of p53-positive tumors might be explained by the development of circulating antibodies to p53 protein. The role of p53 protein in breast cancer is incompletely understood, and the p53 gene should be subjected to detailed analysis of specific mutations.

Hormone resistant prostatic adenocarcinoma. An evaluation of prognostic factors in pre- and post-treatment specimens

Pre- and post-treatment specimens from 47 patients with hormone resistant prostatic carcinoma were compared with each other regarding histological grade and immunoreactivity for p53 protein, neuron specific enolase and c-erbB-2 protein. Significantly more specimens expressed a high malignancy grade when the tumour had become hormone resistant than at the time of initial diagnosis (Gleason P: < 0.0001, WHO P:0.0003). p53 protein immunoreactivity increased significantly with disease progression (P:0.006), while tissue PSA immunoreactivity was reduced in post-treatment specimens (P:0.011). p53 protein expression did not correlate with histological grade or PSA expression and seems to be an independent parameter which participates late in the neoplastic transformation. Thirty-two percent of the tumours were neuron specific enolase positive, but this parameter did not correlate with development of hormone resistance. c-erbB-2 protein reactivity was not recognised.