[Adenovirus-mediated interleukin-24 enhanced the antitumor effect of radiotherapy on nasopharyngeal carcinoma in vitro and in vivo].

Objective: To investigate the inhibitory effect of adenovirus-mediated interleukin-24 (AdVIL-24) in conjunction with ionizing radiation on the growth of CNE-2Z human NPC cells in vitro and in vivo and underlying mechanisms.

Methods: The CNE-2Z cells were transfected with AdVIL-24 alone or combined with radiotherapy. The transfection efficacy of AdVIL-24 in CNE-2Z cells was determined by RT-PCR and Western blot. Cell growth was assessed by MTT assay, apoptosis was detected by flow cytometry through double staining of cells with propidium iodide (PI) and the expressions of P21, P27, cyclin E, CDK2, Bax, Bcl-2 and caspase-3 were detected with semi-quantitative RT-PCR and western blot, respectively. Anti-tumor effect of AdVIL-24 was observed using CNE-2Z human nasopharyngeal carcinoma transplanted tumor in athymic nude mouse model. The volume and weight of the xenografted tumors were measured and the expressions of P21, P27, cyclin E, CDK2, Bax, Bcl-2, caspase-3, CD34 and VEGF and the microvessel density in xenografted tumors were determined by immunohistochemistry analysis.

Results: AdVIL-24 plus radiotherapy induced cell growth inhibition (P < 0.05, Q3d, 4d = 0.916, 1.050) , cell cycle G1 phase arrest(50.37%, P < 0.05, Q = 1.042) and apoptosis (48.82%, P < 0.05, Q = 1.042) , substantial up regulations of P21, P27, the ratio of Bax/Bcl-2 and cleaved caspase-3 and down regulations of cyclin E and CDK2 (P < 0.05, QP21 = 0.959, QP27 = 0.956, Qcyclin E = 1.078, QCDK2 = 1.046, QBax/Bcl-2 = 0.995) in vitro. In the xenografted tumors, AdVIL-24 plus radiotherapy induced cell growth inhibition (P < 0.05, Qvolume14 = 1.053, Qweight = 1.004) , apoptosis (P < 0.05, Q = 0.974) , substantial upregulation of P21, P27, the ratio of Bax/Bcl-2 and cleaved caspase-3 and downregulation of cyclin E and CDK2 (P < 0.05; QP21 = 0.920, QP27 = 0.937, QcyclinE = 1.060, QCDK2 = 1.019, QBax/Bcl-2 = 0.982, Qcleaved-Caspase-3 = 0.927) , decreased the tumor vessel CD34 expression and microvessel density. AdVIL-24 potentially blocked the radiation-induced enhancement of VEGF.

Conclusion: AdVIL-24 gene therapy combined with radiotherapy may be a novel and effective treatment strategy for human NPC.