[Apoptotic effect of bcl-XL antisense oligodeoxynucleotide mediated by lipofectin on cell strain CNE-2Z]

Abstract

Background & objective: Recent studies have shown that overexpression of bcl-XL was detected in human nasopharyngeal carcinoma (NPC) cell strain CNE-2Z, suggesting it may play a pivotal role in tumorigenesis of NPC. The current study was designed to explore the effect of bcl-XL antisense oligodeoxynucleotide (ASODN) on CNE-2Z.

Methods: A 20-mer gapmer ASODN with a full phosphorothioate backbone targeting a sequence unique of the bcl-XL coding region was artificially synthesized. Bcl-XL ASODN was transfected into CNE-2Z cells through lipofectin. The survival rate was assessed by MTT assay and internucleosomal fragmentation of genomic DNA was detected by agarose gel electrophoresis. Apoptotic changes after treatment with ASODN were observed by fluorescence microscopy and flow cytometry.

Results: MTT assay showed that the proliferation of CNE-2Z cells decreased significantly after treatment with ASODN/Lip as compared with control (P < 0.01). ASODN/Lip reduced the proliferation of CNE-2Z in a dose-dependent manner. After treatment with ASODN/Lip for 36 hours, most cells stained with Hoechst 33258/Pl exhibited apoptotic cell morphology such as cell shrinkage, nuclear condensation, and nuclear fragmentation under fluorescence microscope; a apoptotic peak appeared on flow cytometry; a ladder-like pattern of DNA fragmentation appeared on agarose gel electrophoresis.

Conclusion: ASODN can inhibit proliferation of CNE-2Z cells and induce apoptosis of CNE-2Z cells. The results suggest that bcl-XL is a promising target for gene therapy of NPC.