Microarray comparative analysis of melanoma microRNA depending on the tissue fixation method

Abstract

Cutaneous melanoma is the most aggressive form of skin cancer characterized by rapid progression, invasiveness and low survival rates. This explains the importance of optimization of early detection of this tumor. At the present time molecular and genetic methods of cancer investigation are broadly used. One of such methods is microarray that allows to analyze the expression of thousands genes in the single cell. However, this method makes high demands on the quality of samples and research procedure. Today the most common approach for tumor tissue preservation is formalin fixation followed paraffin embedding. This procedure is broadly used in clinical medicine but may affect the structure and availability of nucleic acids of the study sample. The present investigation was done to evaluate the effect of melanoma tissue fixation on the result of microRNA expression analysis by microarray. In this regard, we made comparative study of microRNA expression in melanoma samples fixed in formaldehyde and RNase inhibitor reagent based on ammonium sulfate solution. It has been shown that fixation by formalin as compared to ammonium salts based RNase inhibiting fixator alters the level of 454 microRNAs. Some miRNAs among them are playing an important role in the melanoma progression. Thus, molecular studies of skin tissues by microarray requires more thorough standardization of sample fixation methods or using of special RNA stabilizing solutions. The application of the formalin fixation method to preserve tissue for miRNA expression analysis requires further study.

Keywords

melanoma / microRNA / microarray / formaldehyde

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