Bax gene therapy for human osteosarcoma using cationic liposomes in vivo

Abstract

Abstract. The purpose of this study was to evaluate the anti-tumor effect of human osteosarcoma (HOSM-1) tumor xenografts in nude mice via transfer of the Bax gene using cationic liposomes. The HOSM-1 tumors transplanted into nude mice grew to 5-6 mm in diameter. Following growth of the tumor to this size, liposomes with the Bax plasmid were applied locally to the peripheral tumor (day 0) and were applied 3 times per week for 2 weeks (6 times in total). The tumor growth inhibitory effect was evaluated by measuring the tumor volume up to day 40. The expression of Bax was observed by immunohistochemical analysis and apoptosis was detected using the TUNEL assay. Tumor growth increased only slightly during the administration period, and tumor volume on day 50 was 43% of that in the saline control group. In the tumor margin 48 h after the completion of administration, Bax immunoreactivity was detected and apoptotic cells were clearly increased. Since these results suggested that Bax gene therapy using cationic liposome induced apoptosis in HOSM-1 tumor in vivo, we anticipate that this therapy will be useful for the treatment of osteosarcoma. IntroductionOsteosarcoma is one of the malignant tumors that has a poor prognosis. In particular, relapsed or inoperable cases may require the development of new therapeutic approaches. Gene therapy is an innovative treatment for cancer, and is currently being investigated for osteosarcoma (1).Bcl-2 belongs to a family of proteins that control cell life and death, and may provide an important clue to the development of new treatments for malignant tumors. Bcl-2 and Bcl-xL inhibit cell death, whereas Bax promotes apoptosis. Bax forms a channel with the voltage-dependent anion channel (VDAC) and the adenine nucleotide translocator (ANT) in the mitochondrial membrane, and promotes the release of cytochrome c (2,3). Cytochrome c forms complexes with Apaf-1 and caspase-9, and apoptosis is induced through the activation of caspase-3 (4,5). Thus, Bax gene therapy has been studied for a variety of lung (6), prostate (7), and gastric cancers (8) in vivo. Our in vitro study using osteosarcoma HOSM-1 cells demonstrated good results (9). Therefore, these positive antitumor effects are anticipated to be translated to the in vivo situation.A variety of vectors can be used for gene transfer. Viral vectors and liposomes are currently used as the primary gene transfer vectors for transfer into tumor cells. Viral vectors exhibit antigenicity and toxicity in addition to their excellent gene transfer efficiency, and several studies of viral vectors developing pathogenically have been reported in clinical practice (10-13). Cationic liposomes comprise a positively charged lipid-bilayer membrane that can be used to transfer genes into cells by forming a complex with negatively charged DNA. Liposomal vectors are characterized by their ready availability, low antigenicity and toxicity, and high margin of safety. The number of clinical trials for gene therapy using cationic liposome has recently increased...

A novel triple-regulated oncolytic adenovirus carrying PDCD5 gene exerts potent antitumor efficacy on common human leukemic cell lines

“…Apoptosis-related genes such as p53, p73, Bax and PDCD5 [1][2][3][4] have been used in gene therapy to directly induce apoptosis or by synergistically enhancing the effects of chemotherapy in cancer cells.…”

Adenovirus-mediated PDCD5 gene transfer sensitizes K562 cells to apoptosis induced by idarubicin in vitro and in vivo

“…Recent advances in understanding the molecular pathogenesis of cancer and the rapid development of recombinant DNA technology have made cancer gene therapy feasible in the clinical setting. Apoptosis-related genes such as p53, p73, and Bax [4][5][6] have been used in gene therapy to directly induce apoptosis or by synergistically enhancing the effects of chemotherapy in cancer cells.…”

Improved nonviral cancer suicide gene therapy using survivin promoter-driven mutant Bax

“…2,15,18,21,22,[33][34][35] Bax apoptotic activity is regulated by the translocation of bax to the mitochondria, where it induces mitochondrial membrane permeabilization. 24,25 It is believed that conformational changes in bax under apoptotic stimuli initiate bax translocation to the mitochondria.…”

“…14 Bax, a member of the bcl2 family of genes, has been extensively studied as a candidate for suicide gene therapy. [15][16][17][18][19] Although regulation of bax by hTERT promoter in an adenovirus vector has been shown to provide tumor-specific activity without hepatotoxicity, 2,20 the use of bax as a suicide gene in nonviral plasmid-based vectors has only been successful with cytomegalovirus (CMV) promoter 21,22 and not with TSPs. 23 Recent evidence has shown that bax apoptotic activity is regulated by translocation of cytoplasmic bax to the mitochondria under apoptotic stimuli.…”