Knockdown of a DIS3L2 promoter upstream long noncoding RNA (AC105461.1) enhances colorectal cancer stem cell properties in vitro by down-regulating DIS3L2.

Abstract

A large number of studies have identified plentiful long noncoding RNAs (lncRNAs) associated with the development of multiple cancers. Some lncRNAs have also been found to be strongly linked with stem cell properties such as pluripotency and differentiation. However, only in a few cases have cancer stem cell (CSC)-related lncRNAs been studied. Commonly, the expression and function of lncRNAs are associated with adjacent protein coding transcripts. In the present study, we found an lncRNA (AC105461.1), a promoter upstream transcript of DIS3 mitotic control homolog (Saccharomyces cerevisiae)-like 2 (DIS3L2), may be closely connected with “stem cell-like” properties. We firstly investigated whether the expression of AC105461.1 was down-regulated in colorectal cancer (CRC) tissue samples. Subsequently, we explored the expression pattern of the lncRNA/mRNA gene pair between AC105461.1 and DIS3L2 in 47 CRC specimens by real-time polymerase chain reaction. The results showed that the expression of AC105461.1 was positively correlated with that of DIS3L2. Through CRC cell lines screening experiment, we found that AC105461.1 expression was highest in SW480 and lowest in SW620 cells. Moreover, the results obtained by overexpression experiment indicated that AC105461.1 expression was markedly elevated and DIS3L2 expression level was also apparently upregulated by plasmid cDNA-AC105461.1. In contrast, we further found that AC105461.1 expression level in AC105461.1 siRNA group was significantly knocked down in SW480 cells. Meanwhile, DIS3L2 expression was also markedly decreased. Importantly, we noticed that AC105461.1 overexpression impaired CSC properties, while its knockdown enhanced CSC properties, including self-renewal, migration, and invasion abilities. To further identify the influence of AC105461.1 expression on CSCs properties in CRC, CD133 and CD44, as current universal markers for characterizing CRC stem cells, were selected to perform flow cytometry analysis. As a result, we found that AC105461.1 overexpression reduced the percentage of CD133+CD44+, whereas its knockdown increased the percentage of CD133+CD44+. Taken together, our findings indicated that AC105461.1 may be a regulator of DIS3L2 and a mediator of CRC stem cells, and we speculate that AC105461.1 could be regarded as a promising biomarker and therapeutic target for CRC.