Biomedical subjects

Stanislav Volik

Publications and source records attributed to Stanislav Volik.

3 recordsLinked to original sources

PubMed2003

End-sequence profiling: sequence-based analysis of aberrant genomes.

Genome rearrangements are important in evolution, cancer, and other diseases. Precise mapping of the rearrangements is essential for identification of the involved genes, and many techniques have been developed for this purpose. We show here that end-sequence profiling (ESP) is particularly well suited to this purpose. ESP is accomplished by constructing a bacterial artificial chromosome (BAC) library from a test genome, measuring BAC end sequences, and mapping end-sequence pairs onto the normal genome sequence. Plots of BAC end-sequences density identify copy number abnormalities at high resolution. BACs spanning structural aberrations have end pairs that map abnormally far apart on the normal genome sequence. These pairs can then be sequenced to determine the involved genes and breakpoint sequences. ESP analysis of the breast cancer cell line MCF-7 demonstrated its utility for analysis of complex genomes. End sequencing of approximately 8,000 clones (0.37-fold haploid genome clonal coverage) produced a comprehensive genome copy number map of the MCF-7 genome at better than 300-kb resolution and identified 381 genome breakpoints, a subset of which was verified by fluorescence in situ hybridization mapping and sequencing.

Animals↗

PubMed2003

Reconstructing tumor genome architectures.

Although cancer progression is often associated with genome rearrangements, little is known about the detailed genomic architecture of tumor genomes. The attempt to reconstruct the genomic organization of a tumor genome recently resulted in the development of the End Sequence Profiling (ESP) technique, and the application of this technique to human MCF7 tumor cells. We formulate the ESP Genome Reconstruction Problem, and develop an algorithm to solve this problem in the case of sparse ESP data. We apply our algorithm to analyze human MCF7 tumor cells, and obtain the first reconstruction of the putative architecture of human MCF7 tumor genome. Our results assist in the ongoing ESP analysis of MCF7 tumors by suggesting additional ESP experiments for the completion of a reliable reconstruction of the MCF7 tumor genome, and by focusing BAC re-sequencing efforts.

Algorithms↗

PubMed2002

Integrated genomic and epigenomic analyses pinpoint biallelic gene inactivation in tumors.

Aberrant methylation of CpG islands and genomic deletion are two predominant mechanisms of gene inactivation in tumorigenesis, but the extent to which they interact is largely unknown. The lack of an integrated approach to study these mechanisms has limited the understanding of tumor genomes and cancer genes. Restriction landmark genomic scanning (RLGS; ref. 1) is useful for global analysis of aberrant methylation of CpG islands, but has not been amenable to alignment with deletion maps because the identity of most RLGS fragments is unknown. Here, we determined the nucleotide sequence and exact chromosomal position of RLGS fragments throughout the genome using the whole chromosome of origin of the fragments and in silico restriction digestion of the human genome sequence. To study the interaction of these gene-inactivation mechanisms in primary brain tumors, we integrated RLGS-based methylation analysis with high-resolution deletion maps from microarray-based comparative genomic hybridization (array CGH; ref. 3). Certain subsets of gene-associated CpG islands were preferentially affected by convergent methylation and deletion, including genes that exhibit tumor-suppressor activity, such as CISH1 (encoding SOCS1; ref. 4), as well as genes such as COE3 that have been missed by traditional non-integrated approaches. Our results show that most aberrant methylation events are focal and independent of deletions, and the rare convergence of these mechanisms can pinpoint biallelic gene inactivation without the use of positional cloning.

Alleles↗