Deoxyribonucleic acid (DNA) microarrays are collections of DNA probes arranged on a base pair and the latest commercialized molecular diagnostic technologies that offer high throughput results, more sensitive and require less time. It is the most reliable and widely accepted tool facilitating the simultaneous identification of thousands of genetic elements even a single gene. Microarrays are powerful new tools for the investigation of global changes in gene expression profiles in cells and tissues. The different types of DNA microarray or DNA chip devices and systems are described along with their methods of fabrication and their use. The DNA microarrays assembly process is automatized and further miniaturized. DNA microarrays are used in the search of various specific genes or in gene polymorphism and expression analysis. They will be widely used to investigate the expression of various genes connected with various diseases in order to find the causes of these diseases and to enable their accurate treatment. Generally, microarray analysis is not only applied for gene expression studies, but also used in immunology, genotyping, diagnostics and sequence analysis. Additionally, microarray technology being developed and applied to new areas of proteomics, cancer research, and cellular analysis.

Keywords

Application, DNA, Microarray, Principle.

Circulating tumor cells (CTCs) are the precursors to metastases and increased numbers of CTCs in the peripheral circulation have been shown to correlate with decreased progression-free and overall survival. Although the current clinical utility has been focused on the prognostic significance, other clinical applications are being explored, such as determining if a patient is a candidate for treatment, determining the efficacy of treatment, evaluation for resistance to therapy, prediction of metastatic site, or as an early predictor of metastases. Current methodologies are based on quantifying CTCs and include technologies based on physical, immunological, and molecular techniques. However, these have limitations, of which most of them do not have the ability to perform morphological evaluation. Using morphological evaluation, CTCs in body fluids could be used for primary diagnosis in the setting of cancer of unknown primary (CUP) or in initial or early diagnostic scenarios. Additionally, cytological specimens have been shown to be useful for ancillary testing in patients when surgical resection specimens or biopsies are not available. Evaluation of CTCs should incorporate histological, immunehistochemical, and molecular characterization to enable clinicians to obtain the comprehensive diagnostic, prognostic and therapeutic information necessary to provide appropriate personalized care to cancer patients.

Keywords

Circulating tumor cell (CTC); Circulating; Tumor cell; Cancer; Isolation; Detection; Metastasis; Prognosis.

Abbreviations

CTC: Circulating tumor cell; RT-PCR: Reverse transcriptase-polymerase chain reaction; EMT: Epithelial-mesenchymal transition; MET: Mesenchymal-epithelial transition; TRAIL: Tumor necrosis factor-related apoptosis-inducing ligand; CEA: Carcinoembryonic antigen; CUP: Cancer of unknown primary; CAP: College of American Pathologists; AMP: Association for Molecular Pathology; ASCO: American Society of Clinical Oncology.