MiR-320b/RAD21 axis affects hepatocellular carcinoma radiosensitivity to ionizing radiation treatment through DNA damage repair signaling.

Hepatocellular carcinoma (HCC) is one of the most common malignancies in the world and is associated with high mortality. Ionizing radiation (IR)-based therapy causes DNA damage, exerting a curative effect; however, DNA damage repair signaling pathways lead to HCC resistance to IR-based therapy. RAD21 is a component of the cohesion complex, crucial for chromosome segregation and DNA damage repair, while it is still unclear whether RAD21 is implicated in DNA damage and influences IR sensitivity in HCC. The current research explores the effect and upstream regulatory mechanism of RAD21 on IR sensitivity in HCC. In the present study, RAD21 mRNA and protein expression were increased within HCC tissue samples, particularly within IR-insensitive HCC tissues. The overexpression of RAD21 partially attenuated the roles of IR in HCC by promoting the viability and suppressing the apoptosis of HCC cells. RAD21 overexpression reduced the culture medium 8-hydroxy-2-deoxyguanosine concentration and decreased the protein levels of γH2AX and ATM, suggesting that RAD21 overexpression attenuated IR treatment-induced DNA damage to HCC cells. miR-320b targeted RAD21 3'-UTR to inhibit RAD21 expression. In HCC tissues, particularly in IR-insensitive HCC tissues, miR-320b expression was significantly downregulated. miR-320b inhibition also attenuated IR treatment-induced DNA damage to HCC cells; more importantly, RAD21 silencing significantly attenuated the effects of miR-320b inhibition on IR treatment-induced DNA damage, suggesting that miR-320b plays a role through targeting RAD21. In conclusion, an miR-320b/RAD21 axis modulating HCC sensitivity to IR treatment through acting on IR-induced DNA damage was demonstrated. The miR-320b/RAD21 axis could be a novel therapeutic target for further study of HCC sensitivity to IR treatment.

Wang J ，Zhao H ，Yu J ，Xu X ，Jing H ，Li N ，Tang Y ，Wang S ，Li Y ，Cai J ，Jin J ... -  《-》

MicroRNA-146a-5p enhances radiosensitivity in hepatocellular carcinoma through replication protein A3-induced activation of the DNA repair pathway.

Luo J ，Si ZZ ，Li T ，Li JQ ，Zhang ZQ ，Chen GS ，Qi HZ ，Yao HL ... -  《-》

MiR-92b targets p57kip2 to modulate the resistance of hepatocellular carcinoma (HCC) to ionizing radiation (IR) -based radiotherapy.

Hepatocellular carcinoma (HCC) is one of the most common digestive system malignant tumors. Due to the resistance to radiotherapy, the prognosis in patients with HCC is poor. Based on previous studies and online tools prediction, we hypothesized that miR-92b, which was reported to promote HCC cell proliferation, might bind to p57kip2, a well-known tumor suppressor, to modulate the radioresistance of HCC to ionizing radiation (IR) -based radiotherapy. In the present study, a higher miR-92b expression in HCC tissues and cell lines was observed; a high miR-92b expression was correlated with poorer prognosis in patients with HCC. The overexpression of miR-92b enhanced the radioresistance of HCC to IR treatment by promoting cancer cell proliferation, attenuating cell apoptosis and remove IR-induced cell cycle at G2/M phase. Through directly binding to the 3'-UTR of p57kip2, miR-92b negatively regulated the protein levels of p57kip2; miR-92b inhibition enhanced the cell effect of IR on HCC cells, which could be attenuated by the p57kip2 knockdown, in other words, miR-92b modulated the radioresistance of HCC to IR-based radiotherapy through p57kip2. Taken together, miR-92b inhibits p57kip2 expression in HCC tissues and cell lines, thus enhancing the radioresistance of HCC to IR-based radiotherapy; targeting miR-92b to rescue p57kip2 expression in HCC might help sensitive HCC cells to IR-based radiotherapy.

Wang J ，Zhao H ，Yu J ，Xu X ，Liu W ，Jing H ，Li N ，Tang Y ，Li Y ，Cai J ，Jin J ... -  《-》

MicroRNA-621 Acts as a Tumor Radiosensitizer by Directly Targeting SETDB1 in Hepatocellular Carcinoma.

Radiotherapy is one of the most important treatment methods of tumors. However, the application of radiotherapy in hepatocellular carcinoma (HCC) is limited due to the low tolerance of normal liver cells for radiation and inherent radiation resistance in HCC. With the in-depth study of microRNAs (miRNAs) in tumor therapy, the regulation of tumor radiosensitivity by miRNAs has been a research hotspot in recent years. In the present study, the expression of miR-621 was lower in HCC tissues and cells, and such low expression of miR-621 was associated with poor prognosis in HCC patients. In addition, in vivo and in vitro assays confirmed that the high expression of miR-621 could significantly enhance the radiosensitivity of HCC. Moreover, the expressions of miR-621 and SETDB1 in HCC tissues were negatively correlated. Dual-luciferase reporter assays indicated that miR-621 could directly target the 3' UTR of SETDB1. In addition, miR-621 enhanced the radiosensitivity of HCC cells via directly inhibiting SETDB1. Besides, the miR-621 and/or SETDB1 axis improved the radiosensitivity of HCC cells via activating the p53-signaling pathway. Taken together, miR-621 and/or SETDB1 might be used as a novel therapeutic target for the treatment of HCC.

Shao Y ，Song X ，Jiang W ，Chen Y ，Ning Z ，Gu W ，Jiang J ... -  《-》

Long non-coding RNA NEAT1 promotes hepatocellular carcinoma cell proliferation through the regulation of miR-129-5p-VCP-IκB.

Long non-coding RNA nuclear-enriched abundant transcript 1 (NEAT1) plays an important role in the pathogenesis and development of several types of cancer. However, the functional mechanism of NEAT1 in hepatocellular carcinoma (HCC) remains unclear. NEAT1 and microRNA (miR)-129-5p expression in HCC tissues and cell lines was quantified by means of quantitative PCR. The effects of NEAT1 expression inhibition or upregulation in HCC cell lines were analyzed in terms of cell viability and apoptosis. Biological software was used to predict the binding sites of NEAT1 and miR-129-5p. The expression of the miR-129-5p target molecules valosin-containing protein (VCP) and IκB was detected using Western blotting. The effect of NEAT1 on tumor growth was observed in mouse models of transplanted hepatoma. In the present study, it was concluded that the expression of NEAT1 was significantly increased in the HCC tissues and cell lines. Meanwhile, after downregulating NEAT1 expression in HepG2/Huh7 cell lines, the cell viability was significantly lowered, whereas the corresponding rate of apoptosis was significantly increased. Additionally, it was found that the NEAT1 and miR-129-5p expression showed a negative correlation in HCC tissues. It was further proved that there was a certain negative regulatory mechanism between NEAT1 and miR-129-5p, which was related to the expression of VCP and IκB. The mouse model experiments confirmed that the interference with NEAT1 expression inhibited tumor growth. The study concluded that the overexpression of NEAT1 inhibited the expression of miR-129-5p by regulating VCP/IκB, thereby promoting the proliferation of HCC cells. This study provides new insights into the pathogenesis of HCC, as well as identifying new target genes for diagnosis and treatment.NEW & NOTEWORTHY The results provide strong evidence that upregulated NEAT1 promotes the proliferation of cancer cells in hepatocellular carcinoma (HCC) and this regulatory mechanism depends on the microRNA (miR)-129-5p-valosin-containing protein-IκB axis. The study also indicates that NEAT1 could be a potential therapeutic target for HCC.

Fang L ，Sun J ，Pan Z ，Song Y ，Zhong L ，Zhang Y ，Liu Y ，Zheng X ，Huang P ... -  《-》