Extraction of RNA using fine-needle aspiration samples stored under different conditions: a pilot study

: Diagnosis of lung cancer is achieved by fine-needle aspiration (FNA) techniques such as computed tomography-guided FNA and transbronchial needle aspiration. The purpose of this study was to establish an optimal storing method for molecular testing in FNA samples.

: We performed FNA using a 21-gauge needle in surgically resected lung cancer samples. The aspirates were stored according to the following protocol: in group 1, the aspirate was snap frozen with liquid nitrogen and in group 2, the aspirate was mixed with RNA later. After sample collection from both groups, these samples were stored at -80°C for 6 months. RNA was extracted from each sample using a commercially available RNA extraction kit, and the quality and quantity of RNA were measured. Quantitative real-time reverse transcriptase polymerase chain reaction (RT-PCR) was performed for human actin β (hACTB) and keratin 19 (KRT19).

: FNA was performed from 7 lung cancers. RNA was extracted from all samples. The median total amount of extracted RNA was 33.9 μg for group 1 and 35.8 μg for group 2. The mean RNA integrity number was 3.5 for group 1 and 6.3 for group 2. RT-PCR for hACTB and KRT19 could be successfully performed in all samples; however, the relative gene expression value showed intrasample variation.

: Samples obtained from computed tomography-guided FNA or transbronchial needle aspiration may be used for genetic profiling of lung cancer. RNA can be extracted from FNA samples and can be used for RT-PCR. RNA quality may affect mRNA expression analysis; therefore, an optimal FNA sample storing protocol is essential.