? ? We are developing a nanochip device for manipulating long genomic DNA for high-resolution (kilobase), whole-genome analysis of cancer biomarkers such as gene amplifications, deletions, and translocations. These chromosome structural aberrations are strongly implicated in the process of malignant transformation and are important diagnostic, prognostic, and therapeutic indicators for many types of cancer. Although PCR offers the ultimate (single-base) resolution for detecting and analyzing these anomalies, it is impractical for scanning the entire genome in a comprehensive, linear fashion. Techniques that rely on probing chromosomes, such as metaphase FISH, while providing a pan-genomic view, cannot resolve structures below the Mb range. By probing uncompressed interphase DNA, resolution can be improved, but spatial organization of the genome is lost, so multiplexed and quantitative information is difficult to obtain. By stretching out (linearizing) interphase DNA, using techniques such as """"""""molecular combing"""""""" or """"""""optical mapping,"""""""" it is possible to probe specific loci in a spatially-significant way, and with resolutions in the kb range. However, techniques for mechanically linearizing DNA are inherently variable, leading to inconsistent stretching of molecules, which often cross over and retract upon themselves. This makes it difficult to standardize such techniques as high throughput methods for the biomedical community. We are developing an innovative alternative to mechanical stretching of DNA. We have found that individual DNA molecules, because of the self-avoiding nature of the DNA polymer, will elongate and straighten in a consistent manner when streamed into confining nanometer-scale channels (nanochannels). We have used a novel nanoimprint lithography technique to reliably manufacture nanochannel structures in silicon chips and have demonstrated that DNA in these nanochannels can be visualized and their dimensions measured. We now ask the question, can we quantitatively interrogate this linearized DNA with locus-specific probes for the detection of chromosome structural aberrations associated with cancer? Our product, the nanochannel array chip, will comprise part of an integrated platform for the routine and standardized quantitative analysis of DNA structure that will enable archiving and cross-laboratory comparison of data. ? ? ?
