Abstract
Objective: To investigate the effect of hsa_circ_0000392 (circ_0000392) on the radiosensitivity of cervical cancer cells and explore its potential mechanism. Methods: Cervical cancer tissues and adjacent normal tissues of 42 patients with cervical cancer who were confirmed pathologically for the first time in Huaihe Hospital of Henan University from 2016 to 2019 were collected. According to the patients' response to radiotherapy, the cancer tissues were divided into radio-sensitive tissues and radio-resistant tissues. The expressions of circ_0000392, miR-145-5p, and CRKL in radiation-sensitive, radiation-resistant cervical cancer tissues and Hela, SiHa cells were detected by reverse transcription-quantitative real-time polymerase chain reaction (RT-qPCR) and western blot. SiRNA circ_0000392, miR-145-5p mimic, miR-145-5p inhibitor, pcDNA 3.1-CRKL and its negative control were transfected into HeLa and Siha cells, respectively. After radiation induction, the survival fraction of cells was detected by clone formation assay, apoptosis was detected by flow cytometry, and the expressions of apoptosis-related proteins Bax and Bcl-2 and ERK pathway protein p-ERK1/2 and ERK1/2 were detected by western blot. The targeting relationship between circ_0000392, miR-145-5p and CRKL was verified by dual luciferase reporter gene assay. The effect of circ_0000392 on radiotherapy sensitivity of cervical cancer in vivo was observed in the tumor formation experiment in nude mice. Results: circ_0000392 and CRKL were upregulated in radiation-resistant tissues and cancer cells of cervical cancer, while miR-145-5p was downregulated. The clone formation numbers of Hela and SiHa cells in si-circ_0000392#1+ 6 Gy group were (78.67±10.97) and (71.00±9.54), respectively, which were lower than those in si-Ctrl+ 6 Gy group [(176.00±22.27) and (158.33±17.56), respectively]. The apoptosis rates were (41.55±3.40)% and (31.41±3.29)%, respectively, which were higher than those in si-Ctrl+ 6 Gy group [(15.91±1.37)% and (13.70±1.89)%, P<0.05]. The protein expression of Bax was higher than that of si-Ctrl+ 6 Gy group, and the protein expressions of Bcl2 was lower than those of si-Ctrl+ 6 Gy group. The clone formation numbers of Hela and SiHa cells in si-circ_0000392#1+ miR-145-5p inhibitor+ 6 Gy group were (171.33±25.01) and (137.00±21.66), higher than those in si-circ_0000392#1+ inhibitor NC+ 6 Gy group [(84.67±17.79) vs (71.00±11.00), P<0.05]. The apoptosis rates were (17.41±2.58) % and (15.96±1.25) %, lower than those of si-circ_0000392 #1+ inhibitor NC+ 6 Gy [(40.29±2.92)% and (30.82±2.34)%, respectively, P<0.05]. The expression of Bax protein was lower than that of si-circ_0000392#1+ inhibitor NC+ 6 Gy group, and the expressions of Bcl2 protein were higher than those of si-circ_0000392#1+ inhibitor NC+ 6 Gy group. Circ_0000392 can target miR-145-5p, and CRKL is the downstream target gene of miR-145-5p. The clone formation numbers of Hela and SiHa cells in miR-145-5p mimic+ 6 Gy group were (74.33±10.02) and (66.00±12.17), respectively, which were lower than those of mimic NC+ 6 Gy group [(197.67±17.21) vs (157.67±11.59), respectively, P<0.05]. The apoptosis rates were (45.58±2.16)% and (32.10±3.55)%, higher than those of mimic NC+ 6 Gy group [(15.85±2.45)% and (13.99±1.69)%, respectively, P<0.05]. The expression of Bax protein was higher than that of the mimic NC+ 6 Gy mimic group, and the expression of Bcl2 protein was lower than that of the mimic NC+ 6 Gy group. The clone formation numbers of Hela and SiHa cells in miR-145-5p mimic+ pcDNA-CRKL+ 6 Gy group were (158.00±15.88) and (122.33±13.65), respectively, which were higher than those of miR-145-5p mimic+ pcDNA+ 6 Gy group [(71.33±8.02) vs (65.67±12.22), P<0.05]. The apoptosis rates were (19.50±3.45)% and (17.04±0.94)%, respectively, which were lower than those of miR-145-5p mimic+ pcDNA+ 6 Gy group [(44.33±2.36)% and (32.05±2.76)%, respectively, P<0.05]. The expression of Bax protein was lower than that of miR-145-5p mimic+ pcDNA group+ 6 Gy group, and the expression of Bcl2 protein was higher than that of miR-145-5p mimic+ pcDNA+ 6 Gy group. Sh-circ_0000392 group had smaller tumor volume and decreased tumor weight (P<0.05). The relative mRNA expression levels of circ_0000392, miR-145-5p and CRKL and the relative protein expression levels of CRKL, Bcl-2 and p-ERK1/2 were decreased, while the relative expression level of Bax protein was increased (P<0.05). Conclusion: Circ_0000392 could enhance the radiosensitivity of cervical cancer cells, and its mechanism may be related to the regulation of CRKL/ERK signaling pathway by targeting miR-145-5p, which provides a new reference for enhancing the radiosensitivity of cervical cancer cells.
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