RESUMO
Allelic imbalances (AI) of polymorphic markers at the short arm of chromosome 3 (3p) were mapped using DNA samples of renal cell carcinoma (RCC, 80 cases), breast carcinoma (BC, 95 cases), and epithelial ovarian cancer (EOC, 50 cases) at the same dense panel of markers (up to 24 loci). Six regions with the increased AI frequency (versus the average values determined for all the analyzed 3p markers) at RCC, BC or EOC were found in 3p chromosome. Four 3p regions presumably contain suppressor genes of tumor growth (TSG) observed in the epithelial tumors of various types. Region between D3S2409 and D3S3667 markers in the 3q21.31 region was identified in this study for the first time. The AI peak in D3S2409-D3S3667 region was statistically significant (P < 0.001, according to Fisher) when representative sample of 95 BC patients was analyzed. The data on increased frequency of polymorphic marker allele amplification suggest that the D3S2409-D3S3667 region contains both putative TSG and protooncogenes.
Assuntos
Biomarcadores Tumorais/genética , Neoplasias da Mama/genética , Cromossomos Humanos Par 3/genética , Genes Supressores de Tumor , Neoplasias Renais/genética , Neoplasias Ovarianas/genética , Locos de Características Quantitativas/genética , Feminino , Humanos , MasculinoRESUMO
Studies of the recent decade, including sequencing of numerous human genome regions, allowed a great progress in detection of new tumor suppressor genes (TSG) and development of new means of their identification and analysis. Effective methods of genome scanning and TSG identification combine DNA array techniques and subtraction hybridization. Alternative ways take advantage of new extrachromosomal vector systems (pETE, pETR) and the functional gene inactivation test. A breakthrough was made in localizing new TSG on the human chromosome 3 short arm, which harbors tumor-suppressing regions and is often rearranged in various tumors and in early carcinogenesis. On 3p, only three putative TSG were known five years ago, and at least ten were identified by the end of 2002. The role of new TSG in carcinogenesis is commonly inferred from a decrease in their transcription in tumor cell lines or primary tumors and from their ability to suppress the growth of these. Protein products of 3p TGS play an important part, constraining cell malignization. Some are directly involved in regulating the cell cycle and inducing apoptosis (RASSFIA), others suppress angiogenesis (Sema3B) or metastasis (Hyal-1). Numerous attempts to find mutations in exons of silent genes failed, and at least half of the new candidate genes (RASSFIA, CACNA2D2, BLU, HYAL1, SEMA3B, RAR-beta) proved to be inactivated by promoter methylation.
Assuntos
Cromossomos Humanos Par 3 , Genes Supressores de Tumor , Técnicas Genéticas , Proteínas Supressoras de Tumor , Adenoviridae/genética , Apoptose/genética , Metilação de DNA , Desoxirribonucleases de Sítio Específico do Tipo II/genética , Desoxirribonucleases de Sítio Específico do Tipo II/metabolismo , Terapia Genética/métodos , Vetores Genéticos , Humanos , Hibridização In Situ/métodos , Neoplasias Pulmonares/genética , Glicoproteínas de Membrana/genética , Proteínas de Neoplasias/genética , Neovascularização Patológica/genética , Precursores de Proteínas/genética , Semaforinas , Deleção de Sequência , Transdução Genética , Ubiquitinas/genéticaRESUMO
Allelic deletions along the short arm of human chromosome 3 were mapped in 57 pairs of DNA samples from tumor and normal tissue of renal carcinoma patients in order to locate potential tumor suppressor genes. Twenty highly polymorphic microsatellite markers were used for deletion mapping. Allelic deletions were found in most of the samples (91%). Extended terminal deletions (56%) prevailed over shorter internal and multiple deletions and dominated (65%) in the most aggressive histopathological kidney cancer subtype, clear-cell carcinoma. Frequency analysis of loss of heterozygosity allowed detection of the human chromosome 3 regions most essential for renal carcinomas: the region adjacent to the gene VHL (3p26-p25), the region of homozygous deletions AP20 (3p22-p21.33), and a new region between markers D3S2420 and D3S2409 (3p21.31, 2.2 Mbp).
