RECQ helicase expression in CRC cell lines. (A) RECQ helicase mRNA expression was assessed in CRC lines representing the three major molecular subtypes of CRC, MSS (or CIN) cancers (SW480, V400, V411, AAC1/SB10, and HT29), microsatellite unstable (MSI) cancers (HCT116, LoVo, and LS174T), and CIMP cancers (RKO, SW48, and FET). Expression levels of BLM and RECQL4 mRNA were higher than those of RECQL, RECQL5, and WRN, regardless of molecular subgroup. (B) RECQ helicase mRNA expression compared to normal colonic mucosa for CRC cell lines. RECQL4 expression is significantly higher in the cell lines compared to the normal colonic mucosa (P = .002), whereas RECQL expression is significantly decreased (P < .002). Asterisks indicate statistical significance between the average expression of the indicated helicase in CRC cell line compared to normal colonic mucosa. (C) RECQ helicase Western blot results for CRC cell lines. PCNA and actin were both run as normalization controls in light of the known correlation of RECQ helicase expression with the phase of the cell cycle.