Volume-corrected mitotic index and p53 immunoreactivity in borderline and malignant epithelial ovarian tumors

OBJECTIVE: To determine if there are differences in p53 immunoreactivity and proliferation rate using the volume-corrected mitotic (M/V) index between borderline and malignant ovarian tumors. STUDY DESIGN: Thirteen borderline (7 serous and 6 mucinous) and 17 malignant (14 serous and 3 mucinous) ovarian neoplasms were included in this study. M/V index was calculated according to the formula of Haapasalo et al. Formalin-fixed, paraffin-embedded tissue sections were immunostained with a monoclonal antibody against p53 protein using an avidin-streptavidin method. RESULTS: Carcinomas had a considerably higher M/V index (17.7 +/- 9.8) than borderline tumors (1.5 +/- 1.7, P < .001). The usual mitotic index was also higher in carcinomas than in borderline tumors (24.9 +/- 16.6 versus 1.6 +/- 1.9, P < .001). p53 Immunoreactivity was found in 5/17 carcinomas (29.4%), while all borderline tumors were negative. CONCLUSION: Even though the number of our cases was too small to draw definitive conclusions, our results suggest that M/V index and p53 immunoreactivity may be of some help in the differentiation between borderline and malignant ovarian epithelial tumors.     

Clinicopathological study of metallothionein immunohistochemical expression, in benign, borderline and malignant ovarian epithelial tumors

Metallothioneins (MTs) are a family of cystein-rich metal-binding proteins, which are expressed in normal cells during fetal and postnatal life but also in a variety of human neoplasms. MT expression in human tumors has been linked to resistance to anticancer drugs and differentiation and progression in some types of tumors. This study examined the immunohistochemical expression of MTs in benign, borderline and malignant tumors of ovarian surface epithelium and the possible correlations with clinicopathological parameters and survival. A total of 87 cases with diagnosis of ovarian surface epithelial tumors were included. Specifically, 21 cases of benign cystadenomas (11 serous and 10 mucinous), 14 borderline (low malignant potential tumors, 8 mucinous and 6 serous) and 52 cases of ovarian cancer were analysed. Immunohistochemical expression of MT (cut-off level > 10% of tumor cells) was clearly associated with malignancy. A statistically significant correlation was found between the expression of MT in cancer cases and benign tumors (p < 0.0001) and cancer cases and borderline tumors p = 0.003. In cancer cases a difference was observed between grade I and III (p = 0.002). There was no correlation of MT overexpression with survival in the small number of ovarian carcinoma patients where it was analysed. MT constitutes a marker that characterizes aggressiveness and a high malignant potential in ovarian epithelial tumors. In diagnostic problems MT may help distinguish between benign, borderline and malignant tumors.     

Cytology of peritoneal washings in gynecologic patients. Diagnostic criteria and pitfalls

A total of 226 peritoneal washing specimens obtained from gynecologic patients over a three-year period was reviewed. The diagnostic problems encountered were: differentiating reactive mesothelium from low-grade malignancies; distinguishing between benign ovarian tumors, ovarian tumors of borderline malignancy and low-grade ovarian malignancies; and potential false-positive diagnoses in endometriosis. Low-grade malignancies could be distinguished from reactive mesothelium by evaluating subtle cytologic criteria and by comparing the cells to those of the tumor on histologic section. The differentiation of low-grade epithelial malignancies from benign epithelial lesions caused difficulties that could only be resolved by evaluating the histologic material. Positive peritoneal washings increased the stage in 8 of 110 patients undergoing initial surgery for gynecologic malignancy. Two of 76 patients undergoing a second-look laparotomy had positive washings without histologic evidence of tumor. These ten patients did less well than did those with similar histology but negative washing cytology, despite receiving additional therapy because of the cytologic findings.     

Expression of nucleolar organizer regions (NORs) in ovarian epithelial tumors

AgNOR staining technique was tested in ovarian epithelial tumors to evaluate its diagnostic potential in distinguishing between borderline tumors and well-differentiated carcinomas. In our opinion, the AgNOR count appears useful for assessing differences only between borderline and well-differentiated serous ovarian tumors at stage I of FIGO clinical advancement.     

Immunohistochemical differentiation of malignant mesothelioma, mesothelial hyperplasia and metastatic adenocarcinoma in serous effusions, utilizing staining for carcinoembryonic antigen, keratin and vimentin

The cytologic diagnosis of malignant mesothelioma and its distinction from mesothelial hyperplasia and metastatic adenocarcinoma is consistently difficult; tissue studies utilizing the immunohistochemical profiles of carcinoembryonic antigen (CEA) and keratin have demonstrated a reproducible distinction between these tumors. Mesothelium contains vimentin in addition to keratin, but its characterization is hindered by its poor preservation in formalin fixatives; alcohol fixation is far superior. Alcohol-fixed, Papanicolaou-stained smears of serous fluids from five cases of reactive mesothelium, five metastatic adenocarcinomas and five malignant mesotheliomas were stained with polyclonal CEA, antikeratin monoclonals AE1 and AE3 (combined) and monoclonal vimentin utilizing the peroxidase-antiperoxidase method. The study revealed the excellent preservation of mesothelial vimentin staining in all three groups. The reactive mesothelium and mesothelioma groups were strongly positive for vimentin and keratin whereas the metastatic adenocarcinoma group was only positive for keratin and CEA (except one case). These findings support the results of previous tissue studies, disclosing CEA staining in the metastatic adenocarcinomas, but not in the mesotheliomas, and the inability of keratin staining to distinguish between the two. The findings also emphasize that positive vimentin staining will usually exclude a metastatic adenocarcinoma, but will not distinguish between neoplastic and reactive mesothelial states.     

Peritoneal washings in ovarian tumors. Potential sources of error in cytologic diagnosis

Peritoneal washings were performed on 48 patients with suspected or known ovarian carcinoma. The procedure was part of the initial surgical staging in 27 patients with presumed stage I and II ovarian cancer and was performed during second-look operations in 21 other cases with proven ovarian malignancy. This paper presents the microscopic features of the washings, with particular emphasis on the cytologic differentiation between benign and malignant findings outside of the ovary. Thirty-four cases showed benign or reactive mesothelial cells and no evidence of peritoneal disease. The washings of six patient showed malignant cells, which were confirmed histologically. Notable atypia that mimicked ovarian carcinoma was found in eight patients who had benign or borderline lesions. These findings included papillary and glandlike epithelial structures, with varying degrees of cellular atypia and psammoma bodies. The histologic counterparts of these atypicalities were Müllerian inclusions, mesothelial proliferations and borderline serous tumors. The differential diagnosis between these entities is essential because false-positive cytologic diagnoses may alter postoperative treatment in some patients.     

Bivariate analysis of the p53 pathway to evaluate Ad-p53 gene therapy efficacy.

BACKGROUND: Gene therapy of human tumors with adenovirus vectors presents a clinical research challenge and a potential opportunity in cancer therapy. One of the research challenges is that endpoints like tumor reduction, time to recurrence, and survival do not provide information about whether a potential therapeutic infects the targeted cells or whether the transferred gene functions or induces a cellular response. Therefore, a flow cytometric approach was developed for a wildtype, p53 encoding adenoviral vector (Ad-p53) that provides (1) the relative level of p53 transferred by p53 immunoreactivity, (2) mdm2 immunoreactivity as an assay of p53 activity, and (3) estimates of the percentage of infected cells by dual parameter analysis (p53 versus mdm2). METHODS: Three prostate cancer cell lines (PC-3, LNCaP, DU 145) that are null, wild-type, and mutant for p53, respectively, and two ovarian cancer cell lines (PA1, MDAH 2774) that are wild-type and mutant for p53, respectively, were tested for immunoreactivity and lack of cross-reactivity with the monoclonal antibodies, DO-7 (anti-p53) and IF2 (anti-mdm2). Optimal dual staining conditions for a flow cytometric assay employing saturating levels of antibody were developed and tested by infection of PC-3, PA1, and MDAH 2774 with Ad-p53 or a control virus, Ad-luc. Dual staining with DO-7 and propidium iodide was used to determine any biological effect of the transferred gene. RESULTS: Neither DO-7 nor IF2 showed appreciable cross-reactions by Western blot analysis of representative prostate or ovarian cell lines. By flow cytometric titration, DO-7 appears to be a high avidity antibody (saturation staining of 10(6) DU 145 cells with 0.5ug) whereas IF2 appears less so (optimum signal to noise ratio at 1ug/10(6) cells). Infection with Ad-p53 was detected at 6 to 48 hours post infection as a uniform relative increase in p53 levels over background p53 levels. Coincident increases in mdm2 immunoreactivity were also detected. DNA content measurements of PA1 and MDAH 2774 cells indicated that G1 arrest and/or apoptosis occurred subsequent to Ad-p53 infection. p53 and mdm2 levels and DNA content distributions for Ad-luc infected cells were equivalent to uninfected cells. CONCLUSIONS: A flow cytometric approach to measure the efficacy of an Ad-p53 gene therapy vector was developed that detects not only the gene transferred but also the activity of the transferred gene product.     

p53 protein expression and proliferative activity in imprints of superficial transitional cell carcinoma of the bladder

OBJECTIVE: To investigate p53 protein expression and proliferative activity in imprints of tumor biopsies from superficial transitional cell carcinoma of the bladder in relation to the histologic grade of malignancy and recurrence status. STUDY DESIGN: The study group consisted of 70 cases of superficial transitional cell carcinoma of the bladder. In order to investigate p53 protein expression and Ki-67 expression, an immunocytochemical avidin-extravidin complex technique was performed using monoclonal antibodies p53 D0-7 and proliferating cells correspondingly. RESULTS: Thirty-seven percent of superficial transitional cell carcinoma cases showed positive expression of p53 protein. No correlation was found between p53 protein expression and grade of malignancy (P = .45). p53 Protein expression was statistically correlated with a high Ki-67 labeling index (LI) (P < .001) and recurrence status (P < .001). Forty-seven percent of cases showed a Ki-67 LI > 25%. No correlation was found between a high Ki-67 LI and grade of malignancy (P = .703). A significant difference in high Ki-67 LI between recurrent and nonrecurrent tumors of the same grade (P < .001) and between recurrent and nonrecurrent tumors was found independently of grade (P < .001). CONCLUSION: These results on cytologic material could provide useful information on the biologic behavior of superficial transitional cell carcinoma of the bladder at the time of diagnosis.     

The value of epithelial membrane antigen in the diagnosis of ovarian tumors.

The value of epithelial membrane antigen (EMA) in the diagnosis of ovarian tumors was investigated using an indirect immunoperoxidase staining technique on 91 histologic sections (88 tumors and 3 normal tissues) and 39 ascitic fluid smears (28 from patients with epithelial ovarian tumors and 11 from cases of myoma uteri). The rate of positive EMA staining was highest in malignant tumors (89.2%), second highest in tumors of low malignant potential (33.3%) and lowest in benign tumors (25.0%); normal ovarian tissues were negative for EMA. Of the malignant tumors, all 48 serous cystadenocarcinomas (100%) and 18 of 26 mucinous cystadenocarcinomas (69.2%) stained positively for EMA. In serous cystadenocarcinomas, the EMA staining was mainly localized on the luminal membrane of cells in well-differentiated tumors, but appeared on the entire cell surface and cytoplasm of cells in poorly differentiated tumors. The results of EMA staining on ascitic fluid smears were almost the same as the results for the histologic sections. The intensity and the localization of EMA staining were related to the grade of malignancy in these ovarian tumors. In comparison with staining for other antigens (carcinoembryonic antigen, CA-125 and human keratin protein), EMA was found to be one of the most sensitive markers for the diagnosis of ovarian cancer.     

Characterizing subpopulations of neoplastic cells in serous effusions. The role of immunocytochemistry

OBJECTIVE: To analyze the role of immunochemistry in serous effusions. STUDY DESIGN: We analyzed cell blocks of 18 pleural and 18 peritoneal effusions diagnosed as malignant (18), benign (14) and suspicious (4). They were immunostained by the avidin-biotin complex method with a panel of four monoclonal antibodies--CEA, Ber-EP4, LeuM1 (CD15) and p53--and, for lectins (Ulex europaeus) UEA-l, ConA and ConBr. RESULTS: Seventeen of the 18 cases of adenocarcinoma were positive for CEA (95%), 12 (66.6%) for Ber-EP4, 11 (61%) for CD15 and 11 (61%) for p53. Twelve of the 18 (66.6%) were positive for UEA-1, CEA, Ber-EP4 and CD15. UEA-1 did not react with mesothelial cells. p53 Gave a positive reaction in only one case, reactive mesothelial cells. ConA and ConBr reacted indiscriminately with benign and malignant cells; thus, it was not useful in distinguishing between these cells. CONCLUSION: In this context no antibody used alone is reliable for corroborating a diagnosis, but the selective use of a small panel of three markers (CEA, Ber-EP4 and LeuM1) can be very useful in solving diagnostic difficulties in the cytodiagnosis of serous effusions.     

Chromosome 3 anomalies investigated by genome wide SNP analysis of benign, low malignant potential and low grade ovarian serous tumours

Ovarian carcinomas exhibit extensive heterogeneity, and their etiology remains unknown. Histological and genetic evidence has led to the proposal that low grade ovarian serous carcinomas (LGOSC) have a different etiology than high grade carcinomas (HGOSC), arising from serous tumours of low malignant potential (LMP). Common regions of chromosome (chr) 3 loss have been observed in all types of serous ovarian tumours, including benign, suggesting that these regions contain genes important in the development of all ovarian serous carcinomas. A high-density genome-wide genotyping bead array technology, which assayed >600,000 markers, was applied to a panel of serous benign and LMP tumours and a small set of LGOSC, to characterize somatic events associated with the most indolent forms of ovarian disease. The genomic patterns inferred were related to TP53, KRAS and BRAF mutations. An increasing frequency of genomic anomalies was observed with pathology of disease: 3/22 (13.6%) benign cases, 40/53 (75.5%) LMP cases and 10/11 (90.9%) LGOSC cases. Low frequencies of chr3 anomalies occurred in all tumour types. Runs of homozygosity were most commonly observed on chr3, with the 3p12-p11 candidate tumour suppressor region the most frequently homozygous region in the genome. An LMP harboured a homozygous deletion on chr6 which created a GOPC-ROS1 fusion gene, previously reported as oncogenic in other cancer types. Somatic TP53, KRAS and BRAF mutations were not observed in benign tumours. KRAS-mutation positive LMP cases displayed significantly more chromosomal aberrations than BRAF-mutation positive or KRAS and BRAF mutation negative cases. Gain of 12p, which harbours the KRAS gene, was particularly evident. A pathology review reclassified all TP53-mutation positive LGOSC cases, some of which acquired a HGOSC status. Taken together, our results support the view that LGOSC could arise from serous benign and LMP tumours, but does not exclude the possibility that HGOSC may derive from LMP tumours.     

hMSH2、PCNA蛋白和金葡菌L型感染在卵巢肿瘤中的临床意义

目的 探讨hMSH2(human mut shomolog 2)基因、增殖细胞核抗原(proliferating cell nuclear antigen,PCNA)和金葡菌L型感染在卵巢肿瘤中的表达及临床意义.方法 用免疫组化法检测97例卵巢乳头状癌及23例卵巢乳头状瘤组织中hMSH2、PCNA蛋白以及金葡菌L型抗原的表达,用革兰染色法检测这些组织中有无L型细菌的存在,并用x2检验进行统计学处理.结果 hMSH2蛋白在卵巢恶性肿瘤组织中的阳性表达率明显低于良性肿瘤的(P＜0.01),在卵巢乳头状癌中临床分期Ⅰ、Ⅱ期表达率明显高于Ⅲ、Ⅳ期(P＜0.01),随着病理分级增高而显著降低(P＜0.05),腹腔淋巴结无转移者、无腹水者比有转移、有腹水者明显增高(P ＜0.01 ～0.05).而PCNA蛋白在卵巢恶性肿瘤组织中的阳性表达率明显高于良性肿瘤的(P＜0.01),在卵巢乳头状癌中临床分期Ⅲ、Ⅳ期的表达明显高于Ⅰ、Ⅱ期(P＜0.05),随着病理分级增高而显著增加(P＜0.05),腹腔淋巴结有转移者比无转移者明显增高(P＜0.05),有无腹水者之间差异无统计学意义(P＞0.05).金葡菌L型抗原阳性表达和L型菌的检出率与病理分级、临床分期有明显相关性(P＜0.05),有腹腔淋巴结转移、有腹水者均高于无转移和无腹水者(P＜0.01).结论 hMSH2、PCNA蛋白在卵巢肿瘤中有不同程度的异常表达,均可作为判断卵巢肿瘤生物学行为及患者预后的参考指标,金葡菌L型的感染极有可能导致基因的突变或过表达,因此L型感染可能成为诱发肿瘤形成的原因之一,它们相互协同在卵巢肿瘤发生和发展过程中起重要作用.     

Alpha(v)beta(6) integrin-A marker for the malignant potential of epithelial ovarian cancer.

The mechanism(s) responsible for the progression of non-metastatic or borderline ovarian cancer to invasive Grade I/III ovarian cancer is still unknown. An epithelium-restricted integrin, alpha(v)beta(6), is present in malignant epithelia but not in normal epithelia. We studied the relative expression and distribution of alpha(v)beta(6) integrin in early and late-stage invasive (Grade I and Grade III) and non-invasive (benign and borderline) ovarian tumors of serous, mucinous, endometrioid, and clear-cell carcinoma subtypes, to assess its potential as a marker for epithelial ovarian cancer progression. Sixty-six specimens, including eight normal, 13 benign, 14 borderline, 13 Grade I, and 18 Grade III tumors were evaluated by immunohistochemistry (IHC) using a monoclonal antibody (MAb) against alpha(v)beta(6) integrin. Normal ovarian surface epithelium was negative for alpha(v)beta(6) integrin expression. All 45 carcinomas studied were positive, and the staining intensity significantly correlated with the grade of the tumor. The Grade III carcinomas of all types showed strong staining intensity. Only mucinous benign tissues were positive, and no reactivity was observed in benign serous neoplasms. On the basis of these observations, we hypothesize that the expression of alpha(v)beta(6) integrin is associated with epithelial ovarian cancer and that a gradual increase in the expression of the molecule may be a correlative index of the progression of this disease.     

SM047 immunoreactivity in peritoneal fluids

SM047 is a recently developed monoclonal antibody generated against an ovarian adenocarcinoma cell line. A recent immunohistochemical study has shown that SM047 is strongly expressed in tissue sections of most ovarian serous adenocarcinomas. This study aimed to ascertain whether SM047 staining is of value in cytological preparations of peritoneal fluid. A total of 206 consecutive peritoneal fluids were stained immunocytochemically with SM047, CA125, monoclonal carcinoembryonic antigen (mCEA), Ber-EP4 and cytokeratins (CK7 and 20). SM047 positivity was present in reactive mesothelial cells in 117 of 141 (83%) benign cases in which these were present. SM047 positive tumour cells were present in 22 of 23 (96%) ovarian serous adenocarcinomas and in small numbers of gastric adenocarcinomas (two of three), mesotheliomas (one of two) and pancreatic adenocarcinomas (one of one). All six colorectal and two breast adenocarcinomas were negative with SM047. Reactive mesothelial cells in all cases were positive with CK7 and in most cases with CA125. They were negative with CEA, Ber-EP4 and CK20. All adenocarcinomas were positive with Ber-EP4 and mesothelial cells were always negative. All colorectal adenocarcinomas were positive with CK20. This study shows that SM047 staining may be of value in the diagnosis of an ovarian serous adenocarcinoma in peritoneal fluids. Negative staining helps to exclude a primary ovarian serous adenocarcinoma and is characteristic of colorectal adenocarcinoma. The small numbers of other malignancies in the study precludes a judgement of the value of SM047 staining in these neoplasms. SM047 staining may be useful, as part of a larger panel, in the work up of patients with peritoneal effusions.     

Establishment and characterization of a human cell line derived from a uterine papillary serous carcinoma with wild-type p53 function

Uterine papillary serous carcinoma is an uncommon histologic subtype of endometrial cancer that behaves aggressively and has a poor prognosis. We successfully established a uterine papillary serous carcinoma cell line. The population-doubling time was approximately 16 h. Although loss of p53 function is considered critical for the molecular pathogenesis of uterine papillary serous carcinoma, p53 was not only mutated but functionally active in this cell line. This newly established cell line should be useful for investigating the characteristics of uterine papillary serous carcinoma.     

A new epithelial membrane antigen (Calam 27) as a marker of carcinoma in serous effusions

A new monoclonal antibody (Calam 27) that reacts with a membrane antigen present on cells of epithelial origin, but not on cells of mesothelial origin, was investigated as a means of distinguishing between mesothelial cells and malignant cells in cytologic smears of serous effusions from patients with carcinoma. Immunofluorescence staining of cells in 151 effusions from 109 patients with different diseases showed a good correlation between the cytologic diagnosis on routine preparations and the staining with Calam 27. Calam 27 was also used to study the ploidy and cell cycle kinetics of carcinoma cells versus reactive mesothelial cells and normal cells by flow cytometry; these experiments confirmed that Calam 27 is not reactive with mesothelial cells. In conclusion, Calam 27 staining can help to confirm the cytodiagnoses in cases with carcinomatous effusions.     

Diagnostic utility of BCA-225 in detecting adenocarcinoma in serous effusions

OBJECTIVE: To determine the diagnostic value of the BCA-225 antibody in discriminating adenocarcinoma from benign mesothelium in body cavity effusions. STUDY DESIGN: One hundred four cases of unequivocally benign (34 cases) and malignant (70 cases) serous effusions with cell block material were immunostained for BCA-225 using the ABC method without antigen retrieval. The percentage of positively staining cells in each case was estimated in a blind fashion. RESULTS: BCA-225 stained at least 10% of morphologically malignant cells in 28 of 32 (88%) breast carcinomas and 58 of 67 (87%) adenocarcinomas overall. Neuroendocrine carcinomas (two cases) and one mesothelioma were positive in < or = 5% of their respective tumor cells. Of 34 benign cases, 6 (18%) exhibited positive staining, albeit in rare, morphologically benign cells. CONCLUSION: BCA-225 is able to discriminate adenocarcinoma from reactive mesothelium in cell block preparations and may prove useful as part of an antibody panel.     

Local immune response in serous papillary carcinoma of the endometrium

OBJECTIVE: Serous papillary carcinomas of the endometrium are aggressive tumors that tend to permeate, in a very extensive fashion, to uterine and adnexal lymphatic and vascular channels at an early stage in their evolution, and are associated with a particularly gloomy prognosis. It is generally thought that even tumors apparently limited to the endometrium or confined to an endometrial polyp have a poor outcome. Our study points towards the value of HLA-DR antigen in the outcome of serous papillary endometrial cancer. Our aim was to assess the HLA-DR expression in inactive, endometrial intraepithelial carcinoma (EIC), and invasive serous carcinoma curretage specimens from the endometrial cavity, suggesting a role in immune response to keep tumor proliferation in check. STUDY DESIGN: Thirty-one cases of inactive endometrium, twelve cases of EIC, and thirty-nine cases of serous papillary invasive carcinoma curettings were evaluated for the detection of HLA-DR monoclonal antigen. T helper (TH) marker (CD4) in the tumor stroma of the relevant cases was also studied, given that it is now known that the dependence of immune responsiveness on the class II antigens reflects the central role of these molecules in presenting antigen to TH cells. RESULTS: HLA-DR was expressed in 20 of 31 inactive endometrium (64.5%), 4 of 12 in EIC (33.3%), and in 10 of 39 serous papillary invasive carcinomas (25.6%). CD4 was expressed in 9 of 31 inactive endometrium (29%), 5 of 12 in EIC (42%), and in 26 of 39 serous papillary invasive carcinomas (67%). CONCLUSIONS: The results showed decreased expression of HLA-DR and increased expression of CD4 as the lesion progressed to malignancy. The aberrant expression of HLA-DR by epithelial cells of inactive endometrium, of EIC and of serous papillary invasive carcinomas agrees with the hypothesis of the inactive endometrium - carcinoma in situ sequence as the usual route for the development of serous papillary invasive carcinoma. The immune attract mechanism by low HLA-DR signaling seems to be of minor importance in the malignant and metastatic potential of the serous papillary endometrial tumours.     

Flow cytometric measurement of p53 protein expression and DNA content in paraffin-embedded tissue from bronchial carcinomas

The nuclear protein p53 has been measured in archival lung cancer biopsies. The monoclonal antibody PAb 1801, which recognizes human p53, was used. After immunostaining, the nuclei prepared from paraffin-embedded tissue were stained with propidium iodide for simultaneous measurement of DNA content; 17 of 24 lung cancers were p53 positive. The S-phase fraction in positive tumors was 22.9 +/- 6.4%, as compared to 13.6 +/- 6.1% in negative tumors (P less than 0.02). In ten of the positive tumors (two small cell carcinomas and eight non-small cell carcinomas), the p53 expression varied through cell cycle, whereas in seven tumors (five small cell carcinomas and two non-small cell carcinomas), no such variation of p53 expression was observed. Freezing the nuclear suspensions did not substantially reduce the p53 signals. Control experiments with the SV40-transformed human foreskin fibroblast cell line HSF4-T12 showed that the enzymatic digestion utilized to dissociate paraffin-embedded tissue did not significantly reduce p53 fluorescence. Immunohistochemical staining of biopsy specimens indicated that only cancer cells were overexpressing p53. In conclusion, using the monoclonal antibody PAb 1801, p53 is detectable in cell nuclei prepared from paraffin-embedded bronchial carcinoma biopsies. P53 positive tumors have increased proliferative activity compared to p53 negative tumors. Furthermore, the lack of cell cycle variation of p53 in small cell carcinomas indicates that this pattern may be related to high-grade malignancy.     

Immunohistochemical analysis of p53 and HER-2/neu proteins in human tumors.

We examined samples of tumors of human breast, ovary, and colon of various degrees of malignancy for the expression of p53 protein, using a panel of anti-p53 antibodies and peroxidase immunohistochemistry. Of 66 tumor cases (24 cases of ovarian carcinoma, 23 cases of colon adenocarcinoma, and 19 cases of breast carcinoma), 36 (53%) showed high levels of expression of p53 using a human-specific antibody, and 16 (24%) showed high expression of a mutant form of p53. In the mutant p53-positive breast tumor samples, six (86%) were positive for HER-2/neu reactivity, compared with colon (0/4) and ovarian tumors (1/5). The pattern of p53 intracellular localization and tissue distribution, and the relationship between the expression of mutant p53 and cell differentiation, were also examined; poorly differentiated cells showed either overexpression of p53 or higher levels of mutant p53 in comparison with more normal cells.