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Gastrointestinal stromal tumors (GISTs) are the most common mesenchymal neoplasms of the digestive tract. The prediction of the malignant potential of GISTs is still difficult. Altered cell cycle regulation may underlie the tumorigenesis and/or the progression of human malignancies. Although p53 and Bcl-2 have been extensively investigated in GISTs, little is known about the frequency of expression and possible clinical implications of alterations of other cell cycle regulatory proteins in these neoplasms. We have previously investigated the role of loss of p16(INK4A) by loss of heterozygosity and immunohistochemistry in the progression of GISTs and found that loss of heterozygosity of 9p and loss of p16 expression are confined to malignant GISTs. This has led us to investigate the role of other cell cycle regulatory proteins in these tumors. Twenty-three cases of GIST (9 low malignant potential [LMP], 10 primary malignant, and 4 intra-abdominal recurrences) were examined. All cases were strongly positive for KIT (CD117). Immunohistochemical stains were carried out on tissue microarrays to evaluate the expression of proteins involved in the G(1)-S transition and proteins that regulate apoptosis including Rb, E2F1, cyclin D1, CDK4, CDK6, p27(KIP1), p21(WAF1/CIP1), p53, Mdm2, Bcl-2, and Bax. The positive phenotypes identified were as follows: Rb, 39.1%; E2F1, 69.6%; cyclin D1, 30.4%; CDK4, 100%; CDK6, 30.4%; 39.1%; p27(KIP1), 47.8%; p21(WAF1/CIP1), 39.1%; p53, 43.5%; Mdm2, 17.4%; Bcl-2, 91.3%; and Bax, 100%. Malignant GISTs are more likely to be associated with a positive E2F1 and p53 phenotype and a negative p16 and p27(KIP1) phenotype. It was concluded that aberration of the cell cycle regulators is a frequent finding and may be a contributing factor to the pathogenesis of GISTs. While some alterations are seen in LMP and malignant GISTs and therefore may represent an early event in molecular tumorigenesis of GISTs, other alterations are more common in malignant GISTs than LMP and therefore have potential utility as complementary tools for the prognostication of GISTs.

Objective: Intestinal metaplasia is a well-established risk factor in the development of stomach cancer. However, since the specificity is low it would be of great practical value to find a marker to separate cases of intestinal metaplasia into low and high risk for progression to dysplasia/carcinoma. So far this has not been achieved. CD44 is a cell surface molecule involved in cell-cell and cell-matrix interactions, and the spliced variant 6 has been shown to play a role in the progression of gastric carcinoma. The aim of this study was therefore to evaluate CD44v6 as a marker of increased cancer risk in intestinal metaplasia., Methods: The current study investigated immunohistochemical CD44v6 expression in biopsies of normal gastric mucosa (n = 154) and gastric mucosa with intestinal metaplasia (n = 127). A third group consisted of cancer gastrectomies (n = 117) in which both tumour and uninvolved mucosa was studied. Proximal (cardia) and distal (corpus/antrum) locations were noted in all cases., Results: There was a significant sequential increase in CD44v6 expression from normal mucosa and mucosa showing intestinal metaplasia to uninvolved mucosa adjacent to cancers without and with intestinal metaplasia to tumour. The most striking increase was from 'normal' to intestinal metaplastic mucosa adjacent to cancers. There were no differences between proximal and distal cases in any group., Conclusion: These findings strongly suggest that CD44v6 expression is a late phenomenon in the transformation of intestinal metaplasia to dysplasia/cancer. It may therefore be a useful marker of cancer risk in patients with intestinal metaplasia.

Background: Oral lichen planus (OLP) is a chronic inflammatory condition. Clinically, it is characterised by the presence of a white lace-like lesion on the buccal mucosa, tongue, and gingivae, with erosions and ulceration. The World Health Organisation considers OLP to be a premalignant condition., Aims: To investigate expression of the telomerase RNA component (hTR) in OLP compared with normal control buccal mucosa and to assess the possibility of using hTR expression as a marker for malignant transformation in OLP., Methods: hTR expression was analysed in 40 cases of OLP and 18 normal control buccal mucosa samples using an RNA in situ hybridisation approach., Results: Strong hTR RNA expression was seen in the basal, suprabasal, and to a lesser extent in the upper epithelial layers in 36 of the 40 OLP lesions examined. Infiltrating subepithelial lymphocytes in OLP were also shown to express hTR RNA. Weak hTR RNA expression was seen in seven of the 18 normal control buccal mucosa specimens, with expression confined exclusively to the basal layer of the epithelium and absent in the suprabasal and upper layers., Conclusion: The telomerase RNA component hTR is found to be highly expressed in the epithelium of non-dysplastic OLP lesions. It is possible that this high expression is related to the increased cellular proliferation seen in OLP lesions rather than being an indicator of susceptibility to malignancy. Thus, hTR RNA expression may not be a suitable marker for predicting malignant transformation in OLP.

CD44 is a group of cell surface molecules involved in cell-cell and cell-matrix interactions. CD44 spliced variants (CD44V) have been found to enhance the metastatic potential of rat tumors. Tumors from the breast, colon, and thyroid express many alternatively spliced products; nonneoplastic tissues do not. Some authors suggest that CD44V5 and V6 may play a role in gastric carcinoma. The aim of the current study was to investigate the role of CD44V6 as a prognostic marker and predictor of metastatic potential in gastric carcinomas. One hundred fifty-five cases of gastric adenocarcinomas were studied: 36 cases of early (EGC), 19 cases of intermediate (MGC), and 100 cases of advanced gastric adenocarcinomas (AGC). A monoclonal antibody against CD44V6 (R&D) was used. CD44V6 expression was positively correlated with advanced stage (P = 0.05). Strong positivity was only detected in those cases of AGC with metastases. Patients with CD44V6 positive tumors revealed a lower 3- and 5-year survival rate (P = 0.0002). Immunohistochemical detection of CD44V6 could now be used as an indicator of tumor progression in biopsies of patients with gastric carcinoma.

The objective of this study was to determine the utility of nm23 as an immunohistochemical indicator of prognosis in a large series (157 cases) of malignant melanoma and also in two subsets within this group: stage 1 tumours, whether in radial or vertical growth phase (140 cases); and stage 1 tumours in which a vertical growth phase component was positively identified (123 cases). A secondary objective was to explore the relationship between the immunohistochemical expression of nm23 and established clinical and histological indicators of prognosis in each of these three groups. In all groups it was found that strong immunoreactivity correlated positively with survival and inversely with indicators of poor prognosis, in keeping with transfection and mRNA studies and also with many immunohistochemical studies of other tumour types. That these findings are at variance with earlier reported immunohistochemical studies of melanoma highlights the importance of large case numbers of primary invasive tumours in studies which set out to explore the relationship between immunoreactivity and survival., (Copyright 2000 John Wiley & Sons, Ltd.)

The aims of this study were to establish a profile for the expression of p53 in primary renal cell carcinoma using the polyclonal antibody NCL-CB1 and the monoclonal antibody D07, and to compare the results of staining with both antibodies. Ninety-six cases were studied using formalin-fixed paraffin-embedded tissue. Positive nuclear staining ranged from 5% (D07) to 12% (NCL-CM1). Positive cytoplasmic staining ranged from 7% (D07) to 25% (NCL-CM1) of cases. Interobserver agreement was excellent. The findings suggest that such a low level of immunohistochemical positivity reduces any potential prognostic value for p53 in this tumour type.

The aims of this study were to analyse the expression of p53 by immunohistochemistry in a range of malignant and pre-malignant conditions and to assess the degree of inter-observer variability in interpretation of p53 immunostaining. Formalin-fixed paraffin-embedded sections from 28 colorectal carcinomas (CRC), 40 cervical intraepithelial neoplasia lesions (CIN), 22 transitional cell carcinomas of the bladder (TCC), 10 invasive squamous carcinomas of uterine cervix and 21 squamous cell carcinomas of skin were examined. A polyclonal antibody was used in 90 cases. A monoclonal antibody was used in the remainder. Ten cases were stained with both. Aberrant expression of p53 protein was documented in 48% of squamous cell carcinomas of skin, 29% of CRC, 22% of CIN and 23% of TCC. All cases of squamous cell carcinoma of uterine cervix were negative. Inter-observer variation occurred in 7% of cases examined. This was confined to two tumour groups, TCC and CIN. Our results showed that p53 oncoprotein expression by immunohistochemistry was identified in 26% of cases but the range was wide (0-48%) and appeared to be tumour specific. Inter-observer variability in the interpretation of immunohistochemical staining was low (7%) and was restricted to two tumour groups.

Aims: To assess the consistency and reproducibility of assessment of c-erbB-2 immunostaining, and to examine some of the problems relating to inter- and intraobserver variability in the documentation of positive staining; to profile the spectrum of cytoplasmic and membranous staining in a wide range of tumour types., Methods: A total of 283 neoplasms were examined for immunohistochemical expression of the c-erbB-2 oncoprotein. Three independent observers were required to assess intensity both of membrane and cytoplasmic staining on a three point and then a four point scale. Extent of positive staining was also assessed on a two point scale. A minimum of two weeks elapsed between assessments using the differing scales., Results: Positive membrane staining was documented by one or more observers in 16.6% of tumours examined. This positivity was largely restricted to bladder, renal, and breast tumours. The overall level of disagreement as to the presence or absence of membranous staining was 11.3%. Cytoplasmic staining was identified in 55.5% of tumours studied. The level of disagreement as to the presence or absence of cytoplasmic staining was 26.5%., Conclusions: Intraobserver variability was minimal, indicating that each pathologist was adhering to internal reproducible standards. Interobserver variability was greater, indicating that the interpretation of c-erbB-2 immunostaining may require set guidelines. It is suggested that assessment should be referenced to a standard positive control, that a three tier system for grading of intensity and a two tier system for grading of extent should be adopted, and that the evaluation should be agreed by at least two pathologists. The presence of cytoplasmic staining should continue to be routinely recorded until its biological role and clinical implications are fully understood.

This study documents the reactions of the monoclonal antibody KP-1, which detects histiocytes in paraffin sections, with 137 sarcomas, 48 lymphomas, 28 carcinomas, 7 malignant melanomas and 8 cystosarcoma phyllodes. The soft tissue sarcomas had been previously immunophenotyped. Positive staining was obtained in all categories of sarcoma except clear-cell sarcomas. Most categories of sarcoma showed staining in less than 10% of tumour cells although a minority of leiomyosarcomas showed more extensive staining. Five of 7 malignant melanomas were also positive while all lymphomas and carcinomas were negative. We conclude that KP-1 positivity is not helpful in supporting the histiocytic origin of a tumour and is of limited value in the differential diagnosis of soft tissue sarcomas or their separation from other categories of malignancy.

Sections (5 microns thick) from 101 primary adenocarcinomas (including ovarian, colorectal, gastric, breast, oesophageal, prostatic, pancreatic, endometrial and gall bladder) were incubated wtih anticolon specific antigen (CSA) and anticolon ovarian tumour antigen (COTA) antibodies using the peroxidase antiperoxidase technique with positive and negative controls. Anti-CSA positivity was seen in 19 of 20 colonic adenocarcinomas, but it was also seen in a large number of the other tumours. While anti-COTA staining was positive in 16 of 20 colonic adenocarcinomas and 20 of 30 ovarian adenocarcinomas, it was also positive in a large number of the tumours. Anti-CSA and anti-COTA are not adequately specific in the identification of a colonic or ovarian origin of an adenocarcinoma and cannot reliably be applied to the identification of a metastatic adenocarcinoma of unknown primary site.

Tumour markers now have an established role in tumour diagnosis and patient management. However, antibodies used to detect these tumour markers have in some instances proved unreliable, with a low rate of sensitivity and specificity. In this study we wished to evaluate the role of a commercial antibody to myoglobin as a marker of rhabdomyosarcomas. The purpose of this investigation was to assess the sensitivity and specificity of myoglobin antiserum as a marker of rhabdomyosarcomas. This was performed by reacting a large number of tumours (sarcomas, carcinomas and melanomas) with a polyclonal anti human myoglobin antiserum. Staining was demonstrated in 60% of rhabdomyosarcomas. Only two tumours from a total of 226 non-skeletal muscle tumours showed a positive reaction (0.88%). One was a leiomyosarcoma and the other had been classified as an undifferentiated sarcoma but a rhabdomyosarcoma was included in its differential diagnosis. It is of interest that both had been earlier irradiated. This antiserum was therefore a specific but not a very sensitive tumor marker. Its rate of staining of rhabdomyosarcomas is compared with the results in the literature. A great disparity is found and the reasons for this are discussed.