Abstract: BACKGROUND: Long intergenic non-protein coding RNA 00707 (LINC00707) and microRNA-423-5p (miR-423-5p) are both involved in the occurrence and development of osteoarthritis. Starbase predicts that LINC00707 and miR-423-5p have complementary sequences, but whether LINC00707 and miR-423-5p interact to regulate the progress of osteoarthritis still needs further research.
OBJECTIVE: To investigate whether LINC00707 targets miR-423-5p to affect chondrocyte injury and inflammatory factor secretion in osteoarthritis. 
METHODS: Articular chondrocytes were divided into eight groups: (1) blank control group was given no treatment; (2) interleukin (IL)-1β group was cultured with 10 ng/mL IL-1β for 48 hours; (3) IL-1β+si-NC group was transfected with si-NC and then treated with 10 ng/mL IL-1β for 48 hours; (4) IL-1β+si-LINC00707 group was transfected with si-LINC00707 and then treated with 10 ng/mL IL-1β for 48 hours; (5) IL-1β+miR-NC group was transfected with miR-NC and then treated with 10 ng/mL IL-1β for 48 hours; (6) IL-1β+miR-423-5p group was transfected with miR-423-5p mimic and then treated with 10 ng/mL IL-1β for 48 hours; (7) IL-1β+si-LINC00707+anti-miR-NC group was co-transfected with si-LINC00707 and anti-miR-NC and then treated with 10 ng/mL IL-1β for 48 hours; (8) IL-1β+si-LINC00707+anti-miR-423-5p group was co-transfected with si-LINC00707 and anti-miR-423-5p and then treated with 10 ng/mL IL-1β for 48 hours. Relevant tests were performed at the end of the intervention.
RESULTS AND CONCLUSION: Compared with the blank control group, the mRNA expression of LINC00707, apoptosis rate, protein expression of C-caspase3 and C-caspase9, and levels of tumor necrosis factor-α and IL-6 in articular chondrocytes were increased in the IL-1β group, while there was a decrease in miR-423-5p expression and IL-10 level (P < 0.05). Compared with the IL-1β group, the mRNA expression of LINC00707, apoptosis rate, protein expression of C-caspase3 and C-caspase9, and levels of tumor necrosis factor-α and IL-6 in articular chondrocytes were decreased in the IL-1β+si-LINC00707 group, while miR-423-5p expression and IL-10 level increased (P < 0.05). Compared with the IL-1β+miR-NC group, the protein expression of C-caspase3 and C-caspase9 and levels of tumor necrosis factor-α and IL-6 in articular chondrocytes were decreased in the IL-1β+miR-423-5p group, while miR-423-5p expression and IL-10 level increased (P < 0.05). Compared with the IL-1β+si-LINC00707+anti-miR-NC group, apoptosis rate, protein expression of C-caspase3 and C-caspase9, and levels of tumor necrosis factor-α and IL-6 in articular chondrocytes were increased in the IL-1β+si-LINC00707+anti-miR-423-5p group, while miR-423-5p expression and IL-10 level decreased (P < 0.05). To conclude, inhibiting LINC00707 by targeting miR-423-5p can reduce IL-1β-induced apoptosis and inflammation in articular chondrocytes.

Key words: osteoarthritis, LINC00707, miR-423-5p, interleukin-1β, chondrocyte, apoptosis, inflammatory factor