Vector‐based Ape1 small interfering RNA enhances the sensitivity of human osteosarcoma cells to endostatin in vivo

Abstract

Osteosarcoma is a highly vascular and extremely destructive malignancy, and the survival of patients with osteosarcoma has not improved significantly in recent years. Antiangiogenic therapy currently holds great potential in conjunction with conventional treatment modalities for osteosarcoma. However, there are examples of gradual loss of response, and perhaps acquired resistance to antiangiogenic drugs. The acquired resistance of antiangiogenesis may be associated with a lot of hypoxia-response genes. The human apurinic/apyrimidinic endonuclease (Ape1) protein, a bifunctional redox factor and apurinic/apyrimidinic (AP) endonuclease, plays a crucial role in protecting against cell death due to hypoxia. We therefore hypothesized that Ape1 may contribute to the resistance of antiangiogenic therapy. To investigate the effect of Ape1 on the sensitivity of human osteosarcoma cells to endostatin, we constructed an Ape1 small interfering RNA expression vector, O steosarcoma is the most common malignant bone tumor in children and young people. The peak incidence of osteosarcoma usually occurs in the second and third decade of life, and approximately 1000 new cases a year are diagnosed in the USA. Over the past three decades, advances in treatment have been responsible for improved limb salvage, reduced metastases, and overall higher survival rates.(1) Multiagent doseintensive chemotherapy regimens have resulted in long-term disease-free survival rates of ~60-76% in patients with localized disease.(2) Osteosarcoma patients whose tumors respond poorly to chemotherapy are at a higher risk of relapse and adverse outcome due to the genetic instability and intrinsic concomitant tumor resistance.(3) Angiogenesis inhibitors are new anticancer drugs considered potentially capable of circumventing or significantly delaying acquired drug resistance, because they target the normal -and hence genetically stable -host endothelial cells of a tumor's growing vasculature.(4,5) However, there are examples of gradual loss of response, and perhaps acquired resistance to antiangiogenic drugs or treatment strategies, especially when the drugs are administered as monotherapies. (6) These experiments demonstrate that the genetic background of a tumor cell, in this case the presence or absence of wild-type p53, may be an important determinant of response to antiangiogenic therapy.(7) The acquired resistance to antiangiogenic therapy may be associated with a lot of hypoxia-response genes.(8,9) The human apurinic/apyrimidinic endonuclease (Ape1), a bifunctional redox factor/apurinic/apyrimidinic (AP) endonuclease, plays a crucial role in protecting against cell death due to hypoxia.(10) We therefore hypothesized that Ape1 may contribute to the resistance to antiangiogenic therapy, and the knockdown of Ape1 may enhance tumor sensitivity to antiangiogenic therapy.In the present study, we constructed the specific Ape1 small interfering RNA (siRNA) stable expression vector pSilenceApe1 to knockdown Ape1 expression in the osteosarcoma cells, and to de...

Advantages of bioluminescence imaging to follow siRNA or chemotherapeutic treatments in osteosarcoma preclinical models

“…Wang et al 20 have observed an inhibition of human osteosarcoma xenografts in which the apurinic/apyrimidinic endonuclease gene has been downregulated by RNAi. For this, they have injected short hairpin RNA expression vectors into tumors.…”

“…Moreover, these studies have predominantly decreased the expression of genes associated with cell cycle. [18][19][20][21] In osteosarcomas, one way to evaluate the therapeutic potential of small interfering RNA (siRNA) would be to target expression of RANKL in comparison with its blockage by antibody. However, the main challenge for the successful use of siRNA in vivo is to achieve an efficient delivery of these molecules to the target tissue without off-target effects.…”

Apurinic/Apyrimidinic Endonuclease/Redox Effector Factor-1(APE/Ref-1): A Unique Target for the Prevention and Treatment of Human Melanoma

“…It is well documented that elevated APE/Ref-1 is associated with chemo-and radioresistance in a number of cellular systems (11,77,102). Knockdown of APE/Ref-1 efficiently induced apoptosis or sensitization or both to chemical treatments in many cancer cells (57,115,116,120).…”

Small-molecule BH3 mimetic and pan-Bcl-2 inhibitor AT-101 enhances the antitumor efficacy of cisplatin through inhibition of APE1 repair and redox activity in non-small-cell lung cancer

“…Many of these genes are known to contribute to regulation of angiogenesis. We found that combined treatment with APE1 knockdown by RNA interference and recombinant human endostatin promoted apoptosis and had potent antiangiogenic effects in osteosarcoma through APE1-mediated regulation of VEGF expression 95. Our present data indicate that APE1 expression remained unchanged when A549 cells were treated with AT-101 or CDDP alone, or a combination of AT-101 and CDDP as compared with the control.…”