Molecular and immunohistochemical analysis of the bcl-1/cyclin D1 gene in laryngeal squamous cell carcinomas: correlation of protein expression with lymph node metastases and advanced clinical stage.

BACKGROUND: The molecular pathogenesis of laryngeal squamous cell carcinomas (LSCCs) is still only partially understood, although genetic alterations affecting various protooncogenes or tumor suppressor genes have often been detected. METHODS: To improve their understanding of the role of cyclin D1 in the pathogenesis of LSCCs, the authors investigated the expression of cyclin D1 protein and the amplification status of the bcl-1/cyclin D1 locus in a panel of 58 pathologic samples. RESULTS: Expression of cyclin D1 protein was detected in 23 of the 58 patients (approximately 39%), 14 of whom had lymph node metastases (approximately 61%); of the remaining 35 patients without any detectable cyclin D1 expression, 7 had lymph node metastases (20%). Expression of cyclin D1 was detectable in 5% of the specimens of normal mucosa, 13% of those with mild-to-moderate dysplasia, and 25% of those with severe dysplasia. Amplification of the bcl-1/cyclin D1 locus was detected in 12 of the 49 LSCCs investigated (approximately 24%), 7 of which had lymph node metastases (approximately 58%); of the remaining 37 LSCCs with an apparently normal copy number of the cyclin D1 locus, 12 had lymph node metastases (approximately 32%). The authors found almost complete concordance between locus amplification and protein expression. Statistical analysis showed a correlation between cyclin D1 expression and both the presence of lymph node metastases (P < 0.01) and advanced clinical stage (P < 0.02). CONCLUSIONS: The authors' observations suggest that the deregulation of cyclin D1 expression may be involved in the pathogenesis of more aggressive LSCCs.

p53 tumour suppressor gene and RAS oncogenes: molecular analysis in the chronic and leukaemic phases of essential thrombocythaemia.

A panel of 51 cases of essential thrombocythaemia (ET), in chronic or leukaemic phase, was investigated for p53 gene and RAS oncogenes mutations by PCR-SSCP-direct sequencing. No RAS oncogenes mutations were detected, but p53 mutations were identified in three cases: 1/27 cases (approximately 4%) in chronic phase not undergoing chemotherapy, 1/19 cases (approximately 5%) in chronic phase undergoing chemotherapy, and 1/5 cases (20%) which had progressed to leukaemia. Our results suggest that: (1) p53 gene mutations occur sporadically in the chronic phase of ET, independent of chemotherapy, and may contribute to the progression to the leukaemic phase in a limited number of ET patients; (2) the RAS genes family does not seem to be involved in the pathogenesis of ET, unlike other bcr/abl negative chronic myeloproliferative diseases (CMPDs).

Molecular analysis of cutaneous B- and T-cell lymphomas.

Among extranodal non-Hodgkin's lymphomas, primary cutaneous lymphomas (CLs) represent a consistent group of B- and T-cell malignancies. We investigated the arrangement of Ig and T-cell receptor (TCR) genes, together with the involvement of several oncogenes and the tumor-suppressor gene p53, in a panel of primary cutaneous B- and T-cell lymphomas (CBCLs and CTCLs). Southern blot analysis was performed to detect rearrangements of the Ig, c-myc, bcl-1, bcl-2, bcl-3, bcl-6, and the NFKB2/lyt-10 genes in 52 cases of CBCLs and of the TCR, bcl-3, and NFKB2/lyt-10 genes in 38 cases of CTCLs. tal-1 gene deletions were analyzed in CTCLs by means of polymerase chain reaction (PCR). p53 gene mutations were assayed using PCR, single-strand conformation polymorphism analysis, and direct DNA sequencing in CBCL and CTCL cases. Clonal rearrangements of Ig genes or oncogenes were found in 25 of the 52 CBCLs. In particular, we detected rearrangements of the bcl-1 locus (2 cases), the bcl-2 gene (2 cases), the NFKB2/lyt-10 gene (2 cases), and the bcl-6 gene (1 case); interestingly, 4 of these cases showed a germline arrangement of the Ig genes. Clonal rearrangements of TCR genes were detected in 37 of the 38 CTCLs. Rearrangements of the NFKB2/lyt-10 gene were present in 2 cases and tal-1 gene deletions in 3 CTCL cases; p53 gene mutations were detected in 1 CTCL case. Overall, our data indicate that (1) clonal rearrangement of Ig genes is frequently undetectable by means of Southern blot in CBCLs (60%); (2) genetic lesions are involved in a limited but significant fraction of primary CLs showing a molecular marker of clonality (13/62; 20%); and (3) rearrangements of the bcl-1, bcl-2, or bcl-6 loci, associated with specific subsets of nodal lymphoid neoplasias, are rarely observed in CBCLs. Moreover, our results suggest that tal-1 gene deletions may play a pathogenetic role in non-acute T-cell malignancies and that, in the context of lymphoid malignancies, CLs may represent a favorable target for the possible oncogenic potential of the NFKB2/lyt-10 gene.

Multiple genetic lesions in laryngeal squamous cell carcinomas.

BACKGROUND: To understand the molecular pathogenesis of laryngeal squamous cell carcinomas (LSCCs), this study investigated the involvement of various protooncogene loci (bcl-1, int-2, c-erbB-1, c-myc, ras) and the p53 tumor suppressor gene in 18 patients with LSCC (15 at clinical presentation, 3 in clinical relapse). METHODS: For all patients, the mutations affecting the p53 and the H-, K-, and N-ras genes were evaluated by polymerase chain reaction (PCR), single-strand conformation polymorphism, and the direct sequencing of PCR-amplified fragments. The bcl-1, int-2, c-erbB-1, and c-myc loci of 15 patients were investigated using Southern blot analysis. RESULTS: A mutation of the p53 gene was detected in 5/18 patients (approximately 28%), bcl-1 locus amplification in 4/15 (approximately 26%), c-erbB-1 locus amplification in 2/15 (approximately 13%), and c-myc locus amplification in 1/15 (approximately 6%). The simultaneous presence of more than one genetic lesion was observed in four patients; two showed int-2/bcl-1 coamplification, and two int-2/c-erbB-1 coamplification, one of whom also showed a p53 gene mutation. A novel p53 mutation involving the splice acceptor site of exon 6 was detected in one patient. Two of the five patients positive for p53 mutations had clinical relapses of primary tumors. bcl-1 locus amplification only was observed in patients with lymph node metastases (4/6). All but one of the patients with molecular genetic lesions showed a peculiar infiltrating pattern. CONCLUSIONS: Overall, these results show that alterations of known protooncogenes and the p53 tumor suppressor gene are involved in a large proportion of LSCCs (11/18; approximately 60%) and may suggest that distinct molecular pathways occur in the pathogenesis of these tumors.