[Silence of circBANP increases radiosensitivity of colorectal cancer cells and inhibits growth of subcutaneous xenografts by up-regulating miR-338-3p expression].

Objective: To investigate the effect of circBANP on radiosensitivity of colorectal cancer cells and subcutaneous transplanted tumor in nude mice and its potential molecular mechanism. Methods: The carcinoma and adjacent normal mucosal tissues of 20 patients with colorectal cancer who were surgically resected in Henan People's Hospital from January 2018 to January 2019 were selected. The radio-resistant colorectal cancer cell LoVo/R was established. Real-time quantitative polymerase chain reaction (RT-qPCR) was used to detect the expressions of circBANP and miR-338-3p. The radiation sensitivity was determined by cell clone formation experiment. Cell vitality was detected by using methyl thiazolyl tetrazolium (MTT). The expressions of autophagy-related protein microtubule-associated protein light chain 3 (LC3) and p62 were detected by western blot. The fluorescence intensity of LC3 in cells was detected by immunofluorescence assay. The downstream microRNAs (miRNAs) of circBANP were predicted by Circular RNA Interactome website and further verified by dual luciferase reporter gene assay. The transplanted tumor model of LoVo/R cells in nude mice was established, and the effect of circBANP on the growth of transplanted tumor after radiation was observed. Results: The expression levels of circBANP and miR-338-3p in colorectal cancer tissues were 3.21+ 0.29 and 0.47+ 0.04, respectively, which were significantly higher than 1.00+ 0.07 and 1.00+ 0.05 in adjacent tissues (P<0.05). The circBANP expression level of LoVo/R cells was 3.21±0.34, higher than 1.00±0.07 of LoVo cells (P<0.05), and the expression level of miR-338-3p of LoVo/R cells was 0.33±0.04, lower than 1.00±0.08 of LoVo cells (P<0.05). After 4 Gy irradiation, compared with the control group, the viability of LoVo/R cells in the circBANP silencing group [(34±4)% vs (62±6)%, P<0.05], the cell survival fraction (0.07±0.02 vs 0.27±0.04, P<0.05) were decreased, and the radiation sensitization ratio was 1.843, the expression of LC3Ⅱ/Ⅰin LoVo/R cells increased while p62 expression decreased, the cell autophagy was observed. Autophagy inhibitor chloroquine reversed the increased expression of LC3Ⅱ/Ⅰ and inhibited expression of p62 in LoVo/R cells induced by radiation, and promoted the suppression of cell viability and survival induced by radiation, the radiotherapy sensitization ratio was 1.780. Compared with control group after 4 Gy irradiation, the relative fluorescence intensity of LC3 in circBANP silencing LoVo/R cells decreased (0.11±0.01 vs 1.00±0.12, P<0.05), the expression of LC3-Ⅱ/Ⅰdecreased (1.25±0.13 vs 3.84±0.39, P<0.05) while p62 expression increased (2.76±0.29 vs 1.00±0.08, P<0.05). As predicted by Circular RNA Interactome website and confirmed by double luciferase reporter gene assay, miR-338-3p was the target gene of circBANP. The relative fluorescence intensity of LC3 in circBANP silencing + anti-miR-338-3p + 4 Gy group increased (7.32±0.72 vs 1.00±0.09, P<0.05), the expression level of LC3-Ⅱ/Ⅰ increased (4.13±0.43 vs 2.31±0.23, P<0.05) while p62 expression decreased (0.34±0.03 and 1.00±0.11, P<0.05), the radiotherapy sensitization ratio was 0.596. Nude mice subcutaneously transplanted tumor experiment showed that the tumor volume and weight of circBANP silencing group on 13, 16, 19, 22, 25, 28, and 31 days were lower than those of control group (P<0.05), while the tumor volume and weight of circBANP silencing + anti-miR-338-3p group on days of 13, 16, 19, 22, 25, 28 and 31 after inoculated were higher than those of circBANP+ anti-miR-NC group (P<0.05). Conclusions: CircBANP can regulate the radiosensitivity of colorectal cancer cells by regulating the expression of miR-338-3p, and affect the growth of transplanted tumor in nude mice. CircBANP may be a potential target for enhancing radiosensitivity of colorectal cancer cells.

CircRNA circ-BANP-mediated miR-503/LARP1 signaling contributes to lung cancer progression.

Recently, circular RNAs (circRNAs) attract much attention due to their potential vital functions in multiple human diseases, including cancer. circ-BANP has been reported to modulate colorectal cancer growth. Nevertheless, the relationship between circ-BANP and lung cancer requires to be investigated. In this study, we found circ-BANP was overexpressed in lung cancer tissues. Higher circ-BANP expression was associated with lower survival rate. Moreover, silencing circ-BANP markedly inhibited proliferation, migration and invasion of lung cancer cells in vitro and impaired tumor propagation in vivo. In mechanism, circ-BANP was identified as the sponge of miR-503 while miR-503 targets LARP1. Circ-BANP-induced inhibition of miR-503 led to increased expression of LARP1 in lung cancer. Finally, rescue assays indicated that LARP1 restoration partially reversed the effects of circ-BANP knockdown in lung cancer. In sum, our study illustrated that circ-BANP-mediated miR-503/LARP1 signaling promoted lung cancer growth, migration and invasion, providing a novel insight on the mechanism underlying lung cancer progression.

circBANP promotes colorectal cancer growth and metastasis via sponging let-7d-5p to modulate HMGA1/Wnt/ß-catenin signaling.

Colorectal cancer (CRC) is one of the most common and deadly cancers, and the incidence of CRC is on the rise. Due to the lack of early diagnosis method and high metastasis of the disease, the prognosis of CRC remains very poor. Exploring the underlying molecular mechanisms of CRC is very necessary for effective therapy. In this study, we investigated the function of circBANP in CRC. The results showed that circBANP was elevated in both CRC tissues and cells and its level positively correlated with the stage of CRC. Knockdown of circBANP greatly suppressed the epithelial-mesenchymal transition (EMT) process and CRC cell proliferation, migration, and invasion. In addition, knockdown of circBANP inhibited CRC tumor growth and metastasis in vivo. Further, circBANP directly bound to let-7d-5p and regulated CRC development via acting as a let-7d-5p sponge. Let-7d-5p directly targeted HMGA1 and thus circBANP/let-7d-5p regulated Wnt/ß-catenin signaling via HMGA1. Collectively, circBANP promotes CRC development and metastasis via acting as a let-7d-5p sponge to regulate HMGA1/Wnt/ß-catenin signaling, providing a potential biomarker and therapeutic target for the management of CRC.