Extracellular matrix (ECM) degradation is an essential step that allows tumor cells to penetrate a tissue barrier and become metastatic. Heparanase (HPSE) is an endoglycosidase that specifically degrades heparin sulfate proteoglycans (HSPG), a chief component of ECM, HPSE is not expressed in normal epithelial cells but can be detected in a variety of human carcinomas including pancreatic cancer. In the present study, human pancreatic cancer cell line Panc-1 was transfected with HPSE antisense oligodeoxynucleotide (AS-ODN)in vitro, then the inhibitory effect of AS-ODN on HPSE gene expression and invasive ability of Panc-1 cellsin vitro was examined. The HPSE mRNA and protein expression of Panc-1 cells transfected with AS-ODN was significantly inhibited. However, there were no marked inhibitory effects in Panc-1 cells treated with nonsense oligodeoxynucleotide (NS-ODN). Moreover, a modified Boyden chamber assay demonstrated that transfection with HPSE AS-ODN significantly inhibited invasive potential of Panc-1 cellsin vitro after AS-ODN transfection. This suggests that HPSE AS-ODN may contribute to the inhibition of HPSE mRNA and protein expression, and results in a decrease of the invasive ability of Panc-1in vitro.

The recombinant defective adenovirus vector carrying human PTEN tumor suppressor gene was constructed by using AdEasy-1 system and its expression was detected in human breast cancer cell line MDA-MB-468. Human PTEN cDNA was cloned into adenovirus shuttle plasmid pAdTrack-CMV to generate a recombinant plasmid pAdTrack-CMV-PTEN, then homologeous recombination was carried out in the E. coli BJ5183 by contransforming linearized shuttle vector with adenovirus backbone plasmid pAdEasy-1. The newly recombined defective adenovirus vector Ad-PTEN containing green fluorescent protein (GFP) was packaged and propagated in 293 cells. After being purified by cesium chloride gradient centrifugation, the adenovirus was transfected into human breast cancer cell line MDA-MB-468 in vitro. The expression of PTEN mRNA and protein in infected human breast cancer cell line MDA-MB-468 was detected by RT-PCR and Western blot respectively. The recombinant defective adenovirus vector carrying PTEN gene was constructed successfully. The viral titer of purified adenovirus was 2.5×10¹⁰ pfu/mL, and about 70% breast cancer cells were infected with Ad-PTEN when multiplicity of infection (MOI) reached 50. The exogenous PTEN mRNA and protein were expressed in MDA-MB-468 cells infected with Ad-PTEN by RT-PCR and Western blot. The recombinant defective adenovirus vector of PTEN gene was constructed successfully using AdEasy-1 system rapidly, which paved a sound foundation for gene study of breast cancer.