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Characterization of genetic lesions in non malignant bronchial epithelium, preneoplastic lesions and lung cancer
Abstracts
179
CHARACTERIZATION OF GENETIC LESIONS IN NON MALIGNANT BRONCHIAL EPITHELIUM, PRENEOPLASTIC LESIONS AND LUNG CANCER G Sozzi, M. Miozzo, C.T. Cariani, U. Pastorino*, S. Pilotti**, V. Sundarasen °, P.H. Rabbits °, M.A. Pierotti and G. Della Porta. Division of Experimental Oncology A, *Division of Chest Surgery and **Division of Anatomical Pathology and Cytology, Istituto Nazionale Tumori, Via G. Venezian 1, 20133 Milan, Italy and °MRC Clinical Oncology and Radiotherapeutics Unit, MRC Centre, Cambridge CB2 2QH, UK
To identify and characterize early genetic changes occurring in lung tumor development, we performed a cytogenetic and immunohistochemical analysis of non-malignant bronchial epithelium, precancerous lesions and lung tumor specimens. The cytogenetic analysis revealed complex rearranged karyotypes in 16 tumor samples of different histotypes, being deletions or rearrangements of 3p the most frequent chromosomal abnormality observed (9/13 cases). The analysis of non-malignant bronchial samples of 49 patients showed chromosomal abnormalities in 14 patients, mainly deletions of 3p (3 cases), 11p (1 case), and 17p (3 cases). In two cases with a 17p- chromosome, where the histopathologic examination revealed the presence of a severe dysplasia, mutations of P53 tumor suppressor gene was observed by both immunohistochemistry and direct DNA sequencing. Overexpression of the receptor for growth factors EGFR and HER2/NEU was also observed in 60% of the tumors and 30%of the bronchial mucosa. The present results indicate that specific genetic abnormalities are present both in the normal bronchial epithelium and in preneoplastic lesions and could represent early changes in the multistep lung carcinogenetic process useful for the diagnosis of premalignant lesions and early cancer.
APPLICATION OF PCR-RFLP ANALYSIS TO ALLELE LOSS STUDIES IN SMALL BIOPSIES OF LUNG TUMOURS AND PRE-INVASIVE LESIONS OF THE LUNG. Rabbitts P H1, Sundaresan 1,2, Ganly P S5, Hasleton p3, Rudd R M4, Sinha G4 1. MRC Clinical Oncology and Radiotherapeutics Unit, Cambridge. 2. Department of Histopathology, Addenbrooke's Hospital, Cambridge. 3. Department of Histopathology, Wythenshawe Hospital, Manchester. 4. Department of Medicine & Histopathology, London Chest Hospital, London. 5. Department of Haematology, Auckland Hospital, Auckland, New Zealand.
Conventionally, allele loss has been assessed by Southern blotting, a procedure which requires microgram quantities of DNA. We have recently developed a method of RFLP analysis which is dependent on the PCR, with the advantage that nanogram quantities of DNA can now be genotyped. By PCR-converting probes which identify 11 polymorphic loci on chromosome 3, we have been able to show that loss of alleles on chromosome 3 can be detected using biopsy samples of lung tumours obtained at bronchoscopy. We have extended this approach to include the analysis of formalin-fixed paraffin embedded tissue, where the sample is obtained by microdissection of a cut section on a glass slide. This has allowed us to study allelic loss in samples of bronchial dysplasia obtained during lung resections, and thus to identify the occurrence of genetic changes in pre-invasive lesions of the bronchus. Allelic loss on 3p and 17p has been demonstrated, and for some samples positive staining with antibody to p53 was detected. Three samples of dysplastic bronchial epithelium were obtained from patients without any detectable invasive tumour. These also showed allelic loss on 3p and in one case on 17p. We conclude that somatic genetic changes have been detected in preinvasive lesions in bronchial epithelium, and emphasise that this approach to LOH studies can be applied to archival material.
179
CHARACTERIZATION OF GENETIC LESIONS IN NON MALIGNANT BRONCHIAL EPITHELIUM, PRENEOPLASTIC LESIONS AND LUNG CANCER G Sozzi, M. Miozzo, C.T. Cariani, U. Pastorino*, S. Pilotti**, V. Sundarasen °, P.H. Rabbits °, M.A. Pierotti and G. Della Porta. Division of Experimental Oncology A, *Division of Chest Surgery and **Division of Anatomical Pathology and Cytology, Istituto Nazionale Tumori, Via G. Venezian 1, 20133 Milan, Italy and °MRC Clinical Oncology and Radiotherapeutics Unit, MRC Centre, Cambridge CB2 2QH, UK
To identify and characterize early genetic changes occurring in lung tumor development, we performed a cytogenetic and immunohistochemical analysis of non-malignant bronchial epithelium, precancerous lesions and lung tumor specimens. The cytogenetic analysis revealed complex rearranged karyotypes in 16 tumor samples of different histotypes, being deletions or rearrangements of 3p the most frequent chromosomal abnormality observed (9/13 cases). The analysis of non-malignant bronchial samples of 49 patients showed chromosomal abnormalities in 14 patients, mainly deletions of 3p (3 cases), 11p (1 case), and 17p (3 cases). In two cases with a 17p- chromosome, where the histopathologic examination revealed the presence of a severe dysplasia, mutations of P53 tumor suppressor gene was observed by both immunohistochemistry and direct DNA sequencing. Overexpression of the receptor for growth factors EGFR and HER2/NEU was also observed in 60% of the tumors and 30%of the bronchial mucosa. The present results indicate that specific genetic abnormalities are present both in the normal bronchial epithelium and in preneoplastic lesions and could represent early changes in the multistep lung carcinogenetic process useful for the diagnosis of premalignant lesions and early cancer.
APPLICATION OF PCR-RFLP ANALYSIS TO ALLELE LOSS STUDIES IN SMALL BIOPSIES OF LUNG TUMOURS AND PRE-INVASIVE LESIONS OF THE LUNG. Rabbitts P H1, Sundaresan 1,2, Ganly P S5, Hasleton p3, Rudd R M4, Sinha G4 1. MRC Clinical Oncology and Radiotherapeutics Unit, Cambridge. 2. Department of Histopathology, Addenbrooke's Hospital, Cambridge. 3. Department of Histopathology, Wythenshawe Hospital, Manchester. 4. Department of Medicine & Histopathology, London Chest Hospital, London. 5. Department of Haematology, Auckland Hospital, Auckland, New Zealand.
Conventionally, allele loss has been assessed by Southern blotting, a procedure which requires microgram quantities of DNA. We have recently developed a method of RFLP analysis which is dependent on the PCR, with the advantage that nanogram quantities of DNA can now be genotyped. By PCR-converting probes which identify 11 polymorphic loci on chromosome 3, we have been able to show that loss of alleles on chromosome 3 can be detected using biopsy samples of lung tumours obtained at bronchoscopy. We have extended this approach to include the analysis of formalin-fixed paraffin embedded tissue, where the sample is obtained by microdissection of a cut section on a glass slide. This has allowed us to study allelic loss in samples of bronchial dysplasia obtained during lung resections, and thus to identify the occurrence of genetic changes in pre-invasive lesions of the bronchus. Allelic loss on 3p and 17p has been demonstrated, and for some samples positive staining with antibody to p53 was detected. Three samples of dysplastic bronchial epithelium were obtained from patients without any detectable invasive tumour. These also showed allelic loss on 3p and in one case on 17p. We conclude that somatic genetic changes have been detected in preinvasive lesions in bronchial epithelium, and emphasise that this approach to LOH studies can be applied to archival material.