Effect of CEACAM6 silencing on the biological behavior of human gallbladder cancer cells

Carcinoembryonic antigen-related cell adhesion molecule 6 (CEACAM6) is abnormally expressed in various malignant tumors and thus represents a potential biomarker, although information regarding its role in gallbladder cancer (GBC) is limited. This study aimed to evaluate the expression of CEACAM6 in GBC and the effect of CEACAM6 gene silencing on the proliferation, migration, invasion and apoptosis of human GBC cells. Immunochemistry was used to evaluate CEACAM6 expression in 95 GBC specimens and 40 peritumoral tissue specimens. GBC-SD and SGC-996 cell lines were used for in vitro experiments. CEACAM6 was knocked down by transfection of targeted small interfering RNA (siRNA), and reverse-transcription quantitative PCR and western blot analysis were used to detect knockdown efficiency. Cell Counting Kit-8 and colony formation assays were undertaken to evaluate cell proliferation. Variations in cell migration and invasion were detected by wound-healing and Transwell assays, respectively. Flow cytometry was applied to measure cell apoptosis and cell cycle distribution. CEACAM6 gene expression was significantly greater in GBC tissues than in peritumoral tissues, and its positive expression was associated with poor prognosis. CEACAM6 mRNA and protein expression in the CEACAM6 siRNA treatment group was significantly lower than that in the negative control group and the blank group. CEACAM6 knockdown inhibited GBC cell proliferation, migration and invasion but promoted cell apoptosis. Western blot analysis of invasion- and apoptosis-related proteins matrix metalloproteinase-2, Vimentin, BCL-2 and BAX further confirmed CEACAM6 mRNA depletion promoted cell apoptosis and inhibited invasion. Additionally, CEACAM6 mRNA depletion affected the progression of the GBC cell cycle to increase cell distribution in G(0)/G(1) phase, and to reduce it in G(2)/M phase and S phase. These findings indicated that CEACAM6 overexpression may be related to the tumorigenesis and development of GBC. In summary, depletion of CEACAM6 mRNA suppressed the malignant biological behaviors of human gallbladder cancer cells.