ESTUDIO DE MUTAGÉNESIS INSERCIONAL DEL RETROVIRUS MMTV/HMTV EN MUESTRAS DE ADENOCARCINOMAS MAMARIOS DE MUJERES MEXICANAS

Abstract

In Mexico from 2006 breast cancer is the leading cause of death from malignancy in women, incidence data are reported at 38 per 100,000 habitants. Have identified most of the risk factors, however, the etiology is unknown. The factors identified include: a) Genetic factors: family history of cancer, especially mutations in the BRCA-1 and / or BRCA-2 genes, b) Endocrine factors: long exposure to estrogen, nulliparity, early menarche and late menopause c) Factors Exogenous: diet, alcohol, cigarettes, chemicals, radiation, etc.. Recently, several working groups have suggested the possibility that a retrovirus (the murine mammary tumor virus or MMTV) may be the causative agent of some breast cancers. The aim of this study is to identify a fragment of 250 bp. MMTV env gene in mammary adenocarcinomas in Mexican women and evaluate the retrovirus insertion sites by PCR splinkerette. We analyzed 56 samples of breast adenocarcinoma and uninvolved tissue. Samples were processed and DNA extracted. DNA extraction was performed using the computer QIAcube following manufacturer's instructions. Integrity was verified and quantified for subsequent nested PCR, for which we used oligonucleotide proposed by Wang et al. in 1995. We used a construction made by the env gene of MMTV C3H strain on a plasmid pBR322 and propagated in E.coli HB101 as a positive control reaction, so it was amplified a 500pb fragment of the gene GAPDH to verify the usefulness of the DNAs. Having identified the positive PCR products were sequenced and env these sequences aligned with BLAST 2.2.24. Having detected these MMTV-positive samples were tested by PCR to detect possible splinkerette insertion sites of retrovirus. Detected the presence of sequences similar to MMTV env gene in 16 (40%) of the samples and the tissues unaffected. The alignments made to the amplified sequences showed a similarity of 96 - 98% between the amplified sequences and the MMTV env gene. The analysis made by PCR yielded different sites splinkerette amplification could be detected 12 sequences (genes and intergenic regions) including: protein nucleoral 4, initiation factor 5, a nucleosome assembly protein 1, Factor 6, growth, protein. Sequences can be detected MMTV in mammary adenocarcinomas of Mexican women. The sequences obtained from amplicons detected in breast adenocarcinomas are up to 98% homology to MMTV env gene deposited in the NCBI. Some of the genes identified are involved in cell growth and differentiation processes.