RT2 PCR Assay profiling analysis of lncRNAs expression in colon cancer cells

An increasing number of studies have shown that long noncoding RNA (lncRNA) dysregulation plays an important role in development of various cancers, including colon cancer. Nonetheless, the potential mechanisms of lncRNA in regorafenib-resistance remain unclear. Our research revealed the lncRNA AC069513.3 (MIR570MG) increased in regorafenib-resistant colon cancer cells compared to the regorafenib-sensitive cells. Furthermore, lncRNA AC069513.3 (MIR570MG) sponged miR-145, which declined in regorafenib-resistant colon cancer cell lines. More importantly, overexpression of miR-145 hampered cell proliferation and retrieved colon cancer regorafenib-sensitivity, contrary to the function of lncRNA AC069513.3 (MIR570MG). Dual luciferase reporter assay confirmed that miR-145 bound to 3’-UTR of SMAD3, a transcriptional modulator activated by TGFβ, resulting in blockage of TGFβ /SMAD3-mediated cell growth and cycle progression. Furthermore, ectopic expression of miR-145 inhibitor in the parental cells endowed resistance to regorafenib. Conversely, knockdown of AC069513.3 (MIR570MG) impoverished resistance against regorafenib. In summary, our findings suggested that lncRNA AC069513.3 (MIR570MG) promoted regorafenib resistance via releasing SMAD3 from miR-145, leading to activation of SMAD3-mediated signaling pathways. Long noncoding RNA profiling by RT-PCR Three SW480 clones and three SW480 regorafenib-resistant clones were collected in the present study. RT-PCR based LncRNA expression profiles were obtained with Qiagen custom RT2 PCR Arrays.