Cytotoxic Gene Therapy for Human Breast Cancer In Vitro

Levels of effectiveness of gene therapies targeting survivin and its splice variants in human breast cancer cells

In order to develop an effective strategy of breast cancer therapy targeting survivin and its splice variants survivin-ΔEx3 and survivin-2B, the present study constructed four expression vectors by fusing the survivin antisense gene, the survivin (T34A) gene, the survivin-ΔEx3 antisense gene, and the survivin-2B gene with the enhanced green fluorescent protein (eGFP) gene. Each of these vectors was transiently transfected into the B-Cap-37 human breast cancer cell line. The effects of these four vectors with diverse genes on the proliferation and apoptosis of B-Cap-37 breast cancer cells were examined and compared in vitro using MTT and flow cytometry assays. Results of the MTT assay indicated that all four gene therapy plasmids were most effective at inhibiting the proliferation of B-Cap-37 cells 72 h after transfection. However, the four gene therapies had different rates of cell inhibition. pcDNA3.1(+)-egfp-anti-survivin and pcDNA3.1(+)-survivin (T34A)-egfp had almost equivalent or better effectiveness at suppressing cell growth. pcDNA3.1(+)-egfp-anti-survivin-ΔEx3 moderately inhibited the growth of B-Cap-37 cells. In contrast, pcDNA3.1(+)-survivin-2B-egfp had limited inhibition of cell growth. Similar profile of effectiveness of four gene therapies in soliciting cell apoptosis was also observed. These results suggest the relative importance of targeting survivin and its splice variant survivin-ΔEx3 in breast cancer treatment.

PDX-1 acts as a potential molecular target for treatment of human pancreatic cancer

OBJECTIVES

The purpose of this study was to investigate whether pancreatic and duodenal homeobox factor 1 (PDX-1) could serve as a potential molecular target for the treatment of pancreatic cancer.

METHODS

Cell proliferation, invasion capacity, and protein levels of cell cycle mediators were determined in human pancreatic cancer cells transfected with mouse PDX-1 (mPDX-1) alone or with mPDX-1 short hairpin RNA (shRNA) and/or human PDX-1 shRNA (huPDX-1 shRNA). Tumor cell growth and apoptosis were also evaluated in vivo in PANC-1 tumor-bearing severe combined immunodeficient mice receiving multiple treatments of intravenous liposomal huPDX-1 shRNA.

RESULTS

mPDX-1 overexpression resulted in the significant increase of cell proliferation and invasion in MIA PaCa2, but not PANC-1 cells. This effect was blocked by knocking down mPDX-1 expression with mPDX-1 shRNA. Silencing of huPDX-1 expression in PANC-1 cells inhibited cell proliferation in vitro and suppressed tumor growth in vivo which was associated with increased tumor cell apoptosis. PDX-1 overexpression resulted in dysregulation of the cell cycle with up-regulation of cyclin D, cyclin E, and Cdk2 and down-regulation of p27.

CONCLUSIONS

PDX-1 regulates cell proliferation and invasion in human pancreatic cancer cells. Down-regulation of PDX-1 expression inhibits pancreatic cancer cell growth in vitro and in vivo, implying its use as a potential therapeutic target for the treatment of pancreatic cancer.