Background:The purpose of this study was to confirm that RRM2 as a novel target of HPVE7 involved in cervical cancer angiogenesis.Methods:Gene expression was analysed by RT-qPCR, western blot and immunohistochemistry in cervical cancer tissue and cell lines. Luciferase reporter assay was used to determine the activities of various RRM2 promoters. Secreted VEGF was measured by ELISA. RRM2-mediated capillary tube formation induced by HPVE7 in cervical cancer cells were evaluated using human umbilical vein endothelial cells in vitro. ROS induced by RRM2 in cercal cancer cells was confirmed by flow cytometry. The growth of cervical cancer cell overexpression RRM2 was examined by nude mouse xenograft.Results:RRM2 as a novel downstream target for HPVE7 was upregulated by it at the transcriptional level through the E7-pRb interaction and binding of E2F to the RRM2 promoter region. Immunohistochemical analysis showed that the level of RRM2 positively correlated with the HPVE7 level in human cervical cancer. Functionally, overexpression of RRM2 enhanced the expression of HIF-1α and VEGF via activation of the ERK1/2 signalling pathway in cervical cancer cells, and significantly associated with increased microvessel densities in cervical cancer tissues. In vitro, HPVE7 stimulated RRM2-dependent capillary tube formation by HUVECs, and RRM2-enhanced angiogenesis was VEGF dependent. RRM2-activated ERK1/2 pathway was mediated through production of ROS. In the xenograft mouse model, overexpression of RRM2 in cervical cancer cells enhanced tumour growth as well as microvessel densities.Conclusion:HPVE7 induces upregulation of RRM2, which then promotes cervical carcinogenesis via ROS-ERK1/2-HIF-1α-VEGF-induced angiogenesis. Thus, the inhibition of RRM2 activity may be a novel therapeutic strategy for human cervical cancer.

High mobility group box 1 protein (HMGB1) plays an important role in myocardial ischemia-reperfusion (I/R) injury. B-type natriuretic peptide (BNP) postconditioning has been reported to reduce myocardial I/R injury. The present study investigated whether postconditioning of BNP could reduce myocardial I/R injury by inhibiting HMGB1 expression and the potential mechanisms in rats. The left anterior descending coronary arteries of rats were occluded to induce ischemia for 30 min and reopened to imitate reperfusion for 4 h. The rats were treated with BNP (0.03 μg/kg min, i.v.) 15 min before reperfusion until the end of the procedure, with or without treatment of LY294002 (an inhibitor of phosphoinositide 3-kinase (PI3K), 0.3 mg/kg, i.v.), which was injected 20 min before reperfusion. Lactate dehydrogenase (LDH), creatine kinase (CK), tumor necrosis factor-α (TNF-α), interleukin-6 (IL-6), and infarct size were measured. Phospho-Akt, total Akt, and HMGB1 expression were assessed by immunoblotting. The results showed that treatment of BNP postconditioning could significantly decrease the infarct size and the levels of LDH and CK after 4-h reperfusion (all p<0.05). BNP postconditioning could also significantly inhibit the increases of TNF-α and IL-6 (both p<0.05). In addition, BNP postconditioning could significantly inhibit HMGB1 expression induced by I/R (p<0.05). Administration of LY294002 abolished the effects of BNP postconditioning on myocardial I/R injury and the expressions of phospho-Akt and HMGB1 (all p<0.05). The present study suggests that postconditioning of BNP could protect against myocardial I/R injury which may be associated with inhibiting HMGB1 expression, while PI3K/Akt signaling pathway may be involved in the expression of HMGB1 and the protective effect of BNP postconditioning.

Hepatocellular carcinoma (HCC) is a leading cause of cancer-related death across the world. 1,2 The incidence of HCC is over half a million annually. 3 Despite the significant advances that have been made in available treatments, the prognosis of HCC is still unsatisfied. 4,5 To develop effective treatments, it is important to determine the cellular mechanisms that underly HCC development.

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