Inhibition of skin squamous cell carcinoma proliferation and promote apoptosis by dual silencing of NET-1 and survivin.

The simultaneous silencing of multiple upregulated genes is an attractive and viable strategy to treat many incurable diseases including cancer. In the present study, skin squamous cell carcinoma (SSCC) tissue microarray was constructed and the expression of NET-1 and survivin was identified. The high expression of NET-1 and survivin gene in SSCC was confirmed as an important event for the formation and development of the cancer. A total of 100 primary SSCC patients were included in the present study. Expression of NET-1 and survivin in cancer cells was evaluated immunohistochemically in tissue microarrays. The interaction between NET-1 and survivin in SSCC by co-immunoprecipitation was subsequently verified by producing the siRNA sequence targeting the single gene (siRNA-NET-1 and siRNA-survivin) as well as NET-1 and survivin gene (one-chain-double-target siRNA). The levels of NET-1 and survivin mRNA and protein expression in A431 cells were detected by RT-qPCR and western blotting, and the expression of related genes including vascular endothelial growth factor (VEGF), cortactin, Bcl-2, caspase-3 and -8 was identified using RT-qPCR. The protein localization and expression of NET-1 and survivin in A431 cells were documented by immunohistochemistry and immuno-fluorescence staining. The proliferation and apoptosis of A431 cells were detected by CCK-8 assay and flow cytometry (FCM). The tissue microarray showed that NET-1 and survivin were highly expressed in SSCC, while the correlation analysis showed NET-1 expression was positively associated with survivin. In addition, we reported that using the one-chain-double-target siRNA conjugate composed of NET-1 and survivin siRNA sequences in the same backbone inhibited proliferation and promoted apoptosis of SSCC. The one-chain-double-target siRNA showed further downregulation on NET-1 and survivin mRNA and protein levels compared with NET-1 siRNA or survivin siRNA. It also exhibited greater suppression on proliferation and triggering of apoptosis in A431 cells than NET-1 siRNA or survivin siRNA. This result may be explained by the significant downregulation of VEGF, cortactin and Bcl-2, and upregulation of caspase-3 and -8. NET-1 and survivin were overexpressed in SSCC and an interaction between NET-1 and survivin was identified. The one-chain-double-target siRNA appears to be superior in inhibiting cell proliferation and promoting apoptosis compared with the single target siRNA. NET-1 and survivin may have correlative signaling pathways with VEGF, cortactin, Bcl-2, caspase-3 and -8. Simultaneous silencing of NET-1 and survivin using one-chain-double-target siRNA thus provides an advantageous alternative in the development of therapeutics for SSCC.