Kyösti Nuorva

Lowp53 protein expression in salivary gland tumours compared with lung carcinomas

Fifty-one salivary gland tumours (23 pleomorphic adenomas, 5 Warthins tumours, 12 mucoepidermoid carcinomas, 7 adenoid cystic carcinomas, 3 undifferentiated carcinomas and 1 acinic cell tumour) and 27 lung carcinomas (18 squamous cell carcinomas, 6 adenocarcinomas and 3 small cell carcinomas) were analysed immunohistochemically for the expression ofp53 nuclear phosphoprotein. Eight out of 51 (16%) salivary gland tumours werep53 positive. Three of these were benign and 5 malignant. All 3 benign salivary gland tumours were pleomorphic adenomas and expressed only occasional nuclear positivity with less than 1% of tumour cells positive. Of the 5p53-positive malignant tumours, 3 were mucoepidermoid carcinomas and 2 undifferentiated carcinomas. The malignant salivary gland tumours expressed more than 1% of positive nuclei in every case. Seventeen lung carcinomas werep53 positive (63%). Thirteen of these were squamous cell carcinomas, 3 were adenocarcinomas and 1 small cell lung carcinoma. The results show that mutations of thep53 gene may be infrequent in salivary gland tumours when compared with lung carcinomas. The relatively indolent course of some histological types of malignant salivary gland tumours could be associated with the preservation of the non-mutatedp53 gene in most of these tumours. The presence ofp53 positivity in some pleomorphic adenomas might, on one hand, suggest thatp53 gene alterations are also present in these tumours; on the other hand, the accumulation of thep53 protein in these tumours might also be due to some unknown mechanism, not necessarily related top53 gene mutation.

Presence of human papillomavirus DNA and abnormal p53 protein accumulation in lung carcinoma.

BACKGROUND: In some carcinomas inactivation of the tumour suppressor gene product p53, either by point mutation or indirectly by the human papillomavirus (HPV), has been suggested as two alternative routes to malignant transformation. To test this hypothesis in lung tumours, 43 lung carcinomas were analysed by in situ hybridisation and polymerase chain reaction (PCR) for the presence of HPV DNA, and the results were compared with p53 protein immunohistochemical analysis. METHODS: The presence of HPV DNA in lung carcinoma was detected by nucleic acid in situ hybridisation for HPV types 6, 11, 16, 18, 31, and 33 using nonradioactively labelled DNA probes. Polymerase chain reaction (PCR) analysis was performed on all cases showing positive HPV DNA labelling by in situ hybridisation and in an additional 13 negative cases. Abnormal nuclear accumulation of the p53 protein was revealed by immunohistochemistry using the avidin-biotin-peroxidase complex method and a CM-1 polyclonal anti-human p53 antibody and a monoclonal mutation-specific Pab 240 p53 antibody. RESULTS: HPV DNA was found by in situ hybridisation in 13 lung carcinomas (30%). In all these cases subtype-specific HPV DNA could also be detected by PCR. Abnormal p53 protein accumulation was seen in 21 of the 43 carcinomas (49%), of which 18 were HPV negative. Twelve (57%) of the CM-1 positive cases were also positive for the mutation-specific antibody Pab 240. There was an obvious inverse relationship between the presence of papilloma viral DNA and abnormal p53 protein accumulation. CONCLUSIONS: p53 plays an important part in the development of lung carcinomas and, in some cases, HPV may contribute to it by binding and inactivating the p53 protein.

Comparative analysis ofp53 protein immunoreactivity in prostatic, lung and breast carcinomas

In this study we analysed the expression ofp53 protein in a total of 143 carcinomas immunohistochemically. These consisted of 34 prostatic adenocarcinomas, 59 lung and 50 breast carcinomas. In 28 cases, an average of 2–3 additional sections from different tumour areas were analysed. Forty-nine of the 143 carcinomas (34%) showed typical nuclear immunoreactivity by immunohistochemical staining with thep53 antibody CM-1. Two of the 34 prostatic carcinomas (6%) werep53 positive while 25 of the 59 lung carcinomas (43%) and 22 of the 50 breast carcinomas (44%) showed positivity forp53. By grade: 49% of grade III tumours, 36% of grade II and 5% of grade I tumours werep53 positive. There were significantly morep53-positive cases in grade II–III tumours than in grade I tumours (P= 0.001) when all tumours were taken into account. Further, there were significantly morep53-positive cases in grade III than in grade I–II tumours (P=0.001). In lung tumours there were significantly morep53-positive cases in grade II–III tumours than in grade I tumours (P=0.018). Similarly, there were significantly morep53-positive tumours in grade III breast tumours than in grade I–II tumours (P=0.003). The low incidence ofp53 positivity in prostate carcinomas suggests that mutations of thep53 gene are not as frequent in the neoplastic transformation of these tumours as in lung or breast carcinomas. The association ofp53 positivity with tumours of higher grade suggests thatp53 mutations lead to tumours of a more aggressive type. The analysis of tumours by multiple sections indicates thatp53 positivity is not evenly distributed in tumour tissue. Therefore, analysis of additional tumour areas may reveal positivity some cases, which is not evident if only one section is studied.

p53 and c-erbB-2 expression in schistosomal urinary bladder carcinomas and schistosomal cystitis with premalignant lesions.

Immunoreactivity for p53 and c-erbB-2 proteins was studied in 31 schistosomal urinary bladder carcinomas and 21 cases of schistosomal cystitis with hyperplastic, metaplastic and/or dysplastic (premaligant) lesions. The results were compared with 30 carcinomas and 21 premalignant lesions of the urinary bladder without schistosomiasis. Abnormal nuclear p53 protein accumulation was found in 17/31 schistosomal and in 15/30 non-schistosomal carcinomas and in 8/21 schistosomal cystitis with premalignant lesions of which five showed hyperplasia. No case of non-schistosomal hyperplasia or squamous metaplasia examined showed p53-positivity. In non-schistosomal carcinomas p53 positivity was significantly associated with tumour grade (grade I-II vs grade III tumours: P=0.021) and greater age (P=0.004) while in schistosomal carcinomas no such associations were found. Cytoplasmic membrane-bound positivity for c-erbB-2 oncoprotein was found in comparable percentages in schistosomal and non-schistosomal bladder carcinomas (10%), and in both groups was co-expressed with p53. p53 gene alteration is an important event in the development of both schistosomal and non-schistosomal bladder carcinoma.