Functional role of a long non-coding RNA LIFR-AS1/miR-29a/TNFAIP3 axis in colorectal cancer resistance to pohotodynamic therapy.

Colorectal Cancer (CRC) is one of the most common digestive system malignant tumors. Recently, PDT has been used as a first-line treatment for colon cancer; however, limited curative effect was obtained due to resistance of CRC to PDT. During the past decades, accumulating CRC-related long non-coding RNAs (lncRNAs), microRNAs (miRNAs) and mRNAs have been reported to exert diverse functions through various biological processes; their dysregulation might trigger and/or promote the pathological changes. Herein, we performed microarrays analysis to identify dysregulated lncRNAs, miRNAs and mRNAs in PDT-treated HCT116 cells to figure out the lncRNA-miRNA interactions related to the resistance of CRC to PDT treatment, and the downstream mRNA target, as well as the molecular mechanism. We found a total of 1096 lncRNAs dysregulated in PDT-treated CRC HCT116 cells; among them, LIFR-AS1 negatively interacted with miR-29a, one of the dysregulated miRNAs in PDT-treated CRC cells, to affect the resistance of CRC to PDT. LIFR-AS1 knockdown attenuated, whereas miR-29a inhibition enhanced the cellular effect of PDT on HCT116 cell proliferation and apoptosis. Furthermore, among the dysregulated mRNAs, TNFAIP3 was confirmed to be a direct target of miR-29a and exerted a similar effect to LIFR-AS1 on the cellular effects of PDT. In summary, LIFR-AS1 serves as a competitive endogenous RNA (ceRNA) for miR-29a to inhibit its expression and up-regulate downstream target TNFAIP3 expression, finally modulating the resistance of CRC to PDT. We provide an experimental basis for this lncRNA/miRNA/mRNA network being a promising target in CRC resistance to PDT treatment.