RNA recovery from specimens of duct-washing cytology performed contemporaneously with mammary ductoscopy

Abstract

Objective Conventional cytological diagnosis including duct-washing cytology (DWC) is sometimes performed using ductal epithelial cells collected during mammary ductoscopy; it is useful for detection of early-stage breast cancer such as ductal carcinoma in situ (DCIS). However, conventional cytological diagnosis focuses exclusively on cellular morphology; false negatives and false positives may be caused by inadequate specimen preparation (triggering cell degeneration) or poor examiner diagnostic skills. Molecular diagnosis using RNA biomarkers is expected to compensate for the weaknesses of cytological diagnosis. We previously employed microarray analysis to identify highly expressed genes in DCIS, suggesting that they may be useful for DCIS diagnosis. Here, we explored whether DWC samples yielded RNA of sufficient quantity and quality for RNA biomarker-based diagnosis. Results We extracted RNAs from 37 DWC samples. RNA from 12 samples exhibited RNA integrities of ≥ 6, indicative of moderate-to-high quality. We then showed that cocaine and amphetamine regulated transcript prepropeptide (CARTPT) and breast cancer-associated transcript 54 (BRCAT54) mRNA—previously shown by microarray analysis to be highly expressed in DCIS—were detectable in these samples. Therefore, DWC samples may be useful for molecular diagnosis involving RNA biomarkers.

The Role of Cocaine- and Amphetamine-Regulated Transcript (CART) in Cancer: A Systematic Review

“…It has been shown that CARTPT mRNA is expressed in cytological specimens acquired during duct-washing cytology (DWC) derived from solid papillary carcinomas (SPC), a subtype of ductal carcinoma in situ (DCIS), and in intraductal papillomas. Jikuzono et al [ 49 ] chose CARTPT and breast cancer-associated transcript 54 ( BRCAT54 ) mRNA as markers of quality and quantity of RNA extracted from DWC in the diagnosis of DCIS. DWC samples (12 of 37) were characterized with an RNA integrity of equal or more than 6, representing moderate to high quality.…”

“…mRNA of CARTPT and BRCAT54 were detectable in all the samples subjected to quantitative RT-PCR, as well as the mRNA of HPRT-1 (hypoxanthine phosphoribosyl transferase 1, a housekeeping gene), although the CARTPT / HPRT-1 ratio varied from 0.1 to 14.2 in the few samples measured (values from 0.1, 0.1, 0.2, 2.8 to 14.2). Since the measured markers were detected in all samples, RNA from DWC CARTPT mRNA was implicated as a potential biomarker of DCIS [ 49 ].…”