Expression and role of the long noncoding RNA Linc00909 in chemoradiotherapy for colorectal cancer

Figure 1 Linc00909 expression in therapy-resistant rectal cancer tissues. A: Volcano plot of long noncoding RNA expression; B: Differential expression of Linc00909 in neoadjuvant chemoradiotherapy-resistant vs neoadjuvant chemoradiotherapy-sensitive tissues; C: Differential expression of Linc00909 in rectal cancer samples; D: Receiver operating characteristic analysis of Linc00909 in predicting chemoradiotherapy sensitivity; E and F: Kaplan-Meier analyses of overall survival and disease-free survival, respectively. ^aP < 0.05, ^dP < 0.0001. AUC: Area under the curve; NCRT: Neoadjuvant chemoradiotherapy.

Figure 2 Role of Linc00909 in regulating rectal cancer cell proliferation and apoptosis in vitro. A: Linc00909 overexpression efficiency was measured by real-time quantitative polymerase chain reaction; B: Cell proliferation was assessed using a Cell Counting Kit-8 assay; C and D: Colony formation assays were performed to assess the proliferative capacity of the cells; E and F: Apoptosis was analyzed by flow cytometry. ^aP < 0.05, ^bP < 0.01, ^cP < 0.001. CON: Control; OE: Overexpression; VEC: Vector control.

Figure 3 Linc00909 regulates cell cycle progression and sphere formation in rectal cancer cells in vitro. A and B: Cell cycle distribution across all cell lines was analyzed by flow cytometry; C and D: Sphere formation assays were performed to evaluate the stem cell-like properties of the colorectal cancer cell lines. ^aP < 0.05, ^bP < 0.01, ^cP < 0.001. 5-FU: 5-Fluorouracil; CON: Control; OE: Overexpression; RT: Radiotherapy; VEC: Vector control.

Figure 4 Linc00909 modulates the sensitivity of rectal cancer cells to 5-fluorouracil and radiotherapy. A: Sensitivity to 5-fluorouracil was assessed using a Cell Counting Kit-8 assay in all cell lines; B: Sensitivity to radiation was assessed using a Cell Counting Kit-8 assay in all cell lines; C and D: Radiosensitivity across all cell lines was assessed using a Cell Counting Kit-8 assay. Apoptosis in SW620 cells following treatment with 5-fluorouracil and radiotherapy was analyzed by flow cytometry (C). Apoptosis in DLD1 cells following treatment with 5-fluorouracil and radiotherapy was analyzed by flow cytometry (D). ^aP < 0.05, ^bP < 0.01, ^cP < 0.001, ^dP < 0.0001. CON: Control; OE: Overexpression; VEC: Vector control.

Figure 5 Linc00909 overexpression promotes the growth of colorectal cancer cell-derived subcutaneous xenografts in nude mice. A and B: Linc00909 overexpression increased subcutaneous xenograft tumor volume in nude mice. ^aP < 0.05. OE: Overexpression; VEC: Vector control.

Figure 6 Bioinformatic prediction of microRNAs that interact with Linc00909 and their downstream target genes. A and B: Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses were performed based on the significantly differentially expressed genes identified between the chemosensitive and chemoresistant groups; C: Bioinformatic analysis was used to predict microRNAs that may bind to Linc00909 and their downstream target genes; D and E: The expression levels of miR-625-5p and SOX2 were quantified by real-time quantitative polymerase chain reaction; F-I: SOX2 protein expression was analyzed by western blotting. ^aP < 0.05, ^cP < 0.001. CON: Control; OE: Overexpression; VEC: Vector control.