[Detection of LY6G6D gene exon-intron structure,].

Earlier we have shown high frequency of loss of heterozygosity of microsatellite marker D6S273 within HLA III class region in DNA samples from cervical intraepithelial neoplasias and cervical cancer. According to publications three genes were identified in this region. For detection of D6S273 position we used in silico analysis of mRNA sequences deposited in GenBank (NCBI) and investigated LY6G6D gene expression in tumor cell lines. LY6G6D gene exon borders were analyzed with 5'- or 3'-rapid amplification of cDNA ends. We have found that LY6G6D gene consists of 9 exons and includes two earlier identified genes G6D and G6F. Microsatellite D6S273 is located in the last 8 intron of LY6G6D gene. The third gene LY6G6E consisting of four exons is located in 6 intron of LY6G6D gene in the opposite orientation. We suggest that LY6G6D gene is coding three main mRNA transcripts in the same open reading frame but differ in exon composition: MEGT1 consists of 1-4, 8, 9 exons, G6F consists of 1-6 exons and G6D consists of 7-9 exons of LY6G6D gene. High homology with immunoglobulin superfamily within 20-120 aminoacids of MEGT1 and G6F proteins is shown by in silico translation of their mRNAs.

[c-Kit and PDGFRA mutations and clinico-morphological features of gastrointestinal stromal tumors].

Gastrointestinal stromal tumors (GIST) are the most common mesenchymal neoplasms of the digestive tract. Inherent overexpression of receptor tyrosine kinase KIT (CD117) and mutations in c-Kit or PDGFRA genes are highly significant prognosticators. A first Russian investigation of c-Kit and PDGFRA mutations in GIST was carried out in 60 patients. c-Kit mutations were identified in 83.3% (50/60), the most frequent being mutations in c-Kit exon 11 (73.4%, 44/60). Among them, different mutations were identified in the 5'-end of c-Kit exon 11 in 37 GISTs. Duplications in the 3'-end of c-Kit exon 11 were reported in 7 tumors. Mutations in c-Kit exon 9 (73.4%, 44/60) were found in 5 tumors (8.3 3%, 5/60) while mutations in c-Kit exon 13 (0%, 44/60) and 17 (1.7%, 1/60) were rare. PDGFRA mutations in exon 18 were identified in (8.3 3%, 5/60). Substitution D842V occurred only in one gastric epithelioid-cell GIST. The remaining PDGFRA mutations contained deletions with aminoacids 842-846. There were no c-Kit and PDGFRA mutations in five tumors. Our findings point to a significant correlation between c-Kit and PDGFRA mutations, on the one hand, and tumor site and histological pattern, on the other. Hence, c-Kit and PDGFRA mutation detection should be used as an additional prognosticator for efficacy of target therapy.

[Cervical carcinoma progression-associated genetic alterations on chromosome 6]. / Geneticheskie izmeneniia na khromosome 6, assotsiirovannye s progressiei raka sheiki matki.

To identify the loci associated with progression of cervical carcinoma, chromosome 6 regions were tested for loss of heterozygosity. Detailed analysis with 28 microsatellite markers revealed a high frequency of allelic deletions for several loci of the short (6p25, 6p22, 6p21.3) and long (6q14, 6q16-21, 6q23-24, 6q25, 6q27) arms of chromosome 6. Examination of 37 microdissected carcinoma and 22 cervical dysplasia specimens revealed allelic deletions from the HLA class I-III genes (6p22-21.3) and subtelomeric locus 6p25 were found in more than 40% dysplasia specimens. With multiple microdissection of cryosections, genetic heterogeneity of squamous cervical carcinoma was analyzed, and clonal and subclonal allelic deletions from chromosome 6 were identified. Half of the tumors had clonal allelic deletion of D6S273 (6p21.3), which is in a Ly6G6D (MEGT1) intron in the HLA class III gene locus. The frequency of allelic deletions from the chromosome 6 long arm was no more than 20% in dysplasias. Allelic deletions from two loci, 6q14 and 6q16-21, were for the first time associated with invasion and metastasis in cervical carcinoma.

[Molecular markers of the cervical cancer]. / Molekuliarnye markery raka sheiki matki.

The genome of human papilloma viruses from a high-risk group (HPV types 16 and 18) has been detected in 90% of cervical tumors and, in some cases, in the adjacent normal tissues. The presence of viral DNA is the main molecular marker of this neoplasia. HPV genome may persist in the tumors as episomal and integrative forms at early and late stages of tumor progression. The status of viral DNA and the pattern of its expression are similar in all cells of this tumor cell population and seem to be a marker of tumor cell monoclonality. Antibodies to the products of viral oncogenes E6 and E7 were found only in 35% of the patients with tumor where HPV genome is present. Thus, this criteria cannot be used for diagnostic and prognostic purposes. On chromosome 6 in the cervical tumors, the specific marker of heterozygocity on loci 6p21.3 was found. The marker appears at the precancer stage and may be regarded as a marker of tumor monoclonality. Heterozygocity loss in the specific locus in the region 6q16-21 correlates with tumor progression and suggests that there are potential tumor-suppressor genes in this region of chromosome 6. A group of HPV positive tumors with a hypermethylator phenotype is described. These tumors are characterized by the simultaneous methylation and inactivation of multiple genes, including tumor suppressor genes.