Loss of heterozygosity on chromosome 11q13 in microdissected human male breast carcinomas

3p21, 5q21, and 9p21 allelic deletions are frequently found in normal bronchial cells adjacent to non-small-cell lung cancer, while they are unusual in patients with no evidence of malignancy

Molecular cytogenetic and loss of heterozygosity (LOH) analyses of non-small-cell lung cancer (NSCLC) have shown frequent allelic deletions in a variety of chromosomes, such as 1p, 3p, 5q, 8p, 9p, 11p, 11q, and 17p. Allelic loss at 3p21, 9p21, and 5q21 has also been reported in premalignant epithelial lesions of the bronchus and in normal bronchial cells. These findings suggest that a tissue field of somatic genetic alterations precedes the histopathological phenotypic changes of carcinoma. LOH at chromosomal regions 3p21, 5q21, 9p21, and 17p (TP53) was looked for in the peritumoural normal bronchial cells from 30 archival surgically resected tumours. Microdissected normal bronchial cells from 20 benign cytological smears were also added to the study. Matched populations of lymphocytes, tumour cells, and normal bronchial cells adjacent to the tumour were microdissected from paraffin-embedded tissues, while matched populations of normal bronchial cells and inflammatory cells were microdissected from benign cytological smears (bronchial brushings). Polymerase chain reaction (PCR) amplification was performed utilizing the specific markers D5S346, D3S1300, D9S157, D9S171, and TP53. Within the NSCLC tumour cells, LOH was more frequently found at the 5q21 locus (72% of the informative cases), the 3p21 locus (47%), 9p21 (48%), and 17p (33%). Within the peritumoural normal bronchial cells, LOH at 5q21 was found in 37.5% of the cases, 22% showed LOH at 3p21, 27% at 9p21, and 13% at 17p (TP53). LOH was also detected in one case, in normal bronchial cells obtained from cytological smears at one locus (5q21). In conclusion, normal bronchial mucosa adjacent to NSCLC has frequent allelic losses at 3p21, 5q21, and 9p21, while LOH at these loci is unusual in normal bronchial cells obtained from cytological smears from patients with no evidence of malignancy. LOH at these loci may be present before the onset of the malignant growth. LOH studies may supplement the histopathological evaluation of bronchial cells to detect genotypic alterations in both cytological and biopsy specimens.

A functional investigation of tumor suppressor gene activities in a nasopharyngeal carcinoma cell line HONE1 using a monochromosome transfer approach

Monochromosome transfers of selected chromosomes into a nasopharyngeal carcinoma (NPC) cell line were performed to determine if tumor suppressing activity for NPC mapped to chromosomes 9, 11, and 17. Current information from cytogenetic and molecular allelotyping studies indicate that these chromosomes may harbor potential tumor suppressor genes vital to NPC. The present results show the importance of CDKN2A on chromosome 9 in NPC development. There was no functional suppression of tumor development in nude mice with microcell hybrids harboring the newly transferred chromosome 9 containing an interstitial deletion at 9p21, whereas transfection of CDKN2A into the NPC HONE1 cells resulted in obvious growth suppression. Whereas intact chromosome 17 transfers into HONE1 cells showed no functional suppression of tumor formation, chromosome 11 was able to do so. Molecular analysis of chromosome 11 tumor segregants indicated that at least two tumor suppressive regions mapping to 11q13 and 11q22-23 may be critical for the development of NPC.

Frequent allelic losses on chromosome 13q in human male breast carcinomas

Loss of genetic material on chromosomes 13q and 17 has been suggested to be of importance in the initiation and progression of female breast cancer, but their involvement is less well illustrated in male breast carcinomas. The present study was designed to investigate the incidence of allelic loss and microsatellite instability for chromosomes 13q, 17p and 17q in 13 sporadic male breast carcinomas using matched normal-tumour DNA samples and seven polymorphic microsatellite markers. Genetic imbalance was found in one or more informative markers in 85% of the patients, with more frequent loss of heterozygosity and microsatellite instability at loci on chromosome 13q. Thus, a high incidence of allelic losses was observed at the retinoblastoma gene (4/6) and likewise at the D13S263 locus (7/12), which also exhibited the highest frequency of microsatellite instability. The intragenic microsatellite in intron 1 of the TP53 gene on chromosome 17p revealed loss of heterozygosity in 3 of 8 informative patients. The investigated proximal region of chromosome 13q is postulated to harbour several potential tumour suppressor genes associated with female breast cancer. The high incidence of allelic losses at the D13S263 microsatellite, located distal to both the BRCA2 and the Brush-1 loci but proximal to the retinoblastoma gene, possibly indicates the presence of an additional tumour suppressor gene which may be involved in male breast carcinomas. However, this hypothesis needs verification in an extended study of male breast carcinomas.

Loss of heterozygosity on chromosome 11q13 in lobular lesions of the breast using tissue microdissection and polymerase chain reaction

Demonstration of identical allelic loss on chromosome 11q13 in synchronous in situ (DCIS) and invasive ductal (IDC) breast carcinoma has provided molecular evidence of the progression of DCIS to IDC. We investigated loss of heterozygosity (LOH) at chromosome 11q13 in the spectrum of "marker/premalignant" and "malignant" lobular lesions of the breast, including atypical lobular hyperplasia (ALH), lobular carcinoma in situ (LCIS), and infiltrating lobular carcinoma (ILC). Thirty-eight cases with various combinations of ALH, LCIS, and ILC were studied. Synchronous ductal lesions were present in 9 of 38 cases. Areas of interest were specifically isolated by tissue microdissection. The extracted DNA was amplified by polymerase chain reaction (PCR) and analyzed with two polymorphic markers for chromosome 11q13 (INT2 and PYGM). LOH at 11q13 was identified in ILC and LCIS in approximately one third of informative cases. LCIS in association with ILC showed a loss in 50% of cases, whereas pure LCIS in the absence of ILC had a much lower frequency of LOH, which was comparable to that of pure ALH. These results suggest that LOH on chromosome 11q13 may play an important role in development of ILC, similar to that of IDC from DCIS/ADH. Additionally, frequent LOH in ILC and LCIS associated with ILC and a significantly lower and comparable frequency of LOH in LCIS without ILC and ALH implies that genetic alteration(s) on chromosome 11q13 may be important in the transition of LCIS to ILC. LOH was detected in three of nine synchronous ductal lesions (one IDC and two DCIS), confirming our earlier findings and indicating that lobular and ductal neoplasia in the breast show some similar genetic changes. We hypothesize that LOH may help in separating morphologically similar yet genetically different subgroups of ALH and LCIS into one group with genetic changes and an increased potential to progress to invasive cancer and another group, the "marker" lesions of LCIS/ALH, that remain stable or possibly regress.