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Local delivery system of cytotoxic agents to tumors by focused
sonoporation
K, Iwanaga1, T, Nishihara2, and K, Tominaga1
1Department
2Department
of Science of Physical Function, Division of Maxillofacial Surgery, Kyushu Dental Univercity.
of Health Promotion, Divison of Infections and Molecular Biology, Kyushu Dental Univercity.
Recently, ultrasound-targeting microbubble destruction has been employed in molecular gene therapy, and a
new potent nonviral gene transfer method known as ‘sonoporation’ has been developed. We investigated the
efficiency of sonoporation toward growth inhibition of human gingival squamous carcinoma cell line, Ca9-22,
in vitro and in vivo. We found that the delivery of bleomycin (BLM) by sonoporation induced cytotoxic effect
toward Ca9-22 cells in vitro. Our in vivo results showed that tumors nearly disappeared in Ca9-22
cell-implanted nude mice treated with a low dose of BLM followed by sonoporation. Thus, we used
sonoporation to transfect a cdtB-expressing plasmid into Ca9-22 cells and examined cell viability in vitro and in
vivo. We found that an administration of cdtB-expressing plasmid followed by sonoporation induced marked
growth inhibition of Ca9-22 cells and apoptotic cells were also observed in vitro and in vivo[1].
In addition, we developed a specific drug delivery system for squamous cell carcinoma that uses sonoporation
with the anti-epidermal growth factor receptor (EGFR) antibody. Administration of a low dose of BLM by
sonoporation with the anti-EGFR antibody produced a marked growth inhibition of Ca9-22 cells in vitro.
Interestingly, the population of apoptotic cells was remarkably increased when a low dose of BLM was
delivered using sonoporation with the Fab fragment of the anti-EGFR antibody[2].
However, microbubbles are unstable and their targeting ability is insufficient for clinical use. To circumvent
these problems, we developed nobel polyethyleneglycol (PEG) modified liposomes (Nano bubble liposome)
containing perfluoropropane, which is an ultrasound imaging gas. Polyethylene glicolylated (PEG) liposome
avoids uptake by the reticuloendothelial system, thus improving drug delivery to tumor while decreasing
systemic toxicity. PEG liposomes containing doxorubicin, Doxil®, have been used to treat Koposi’s sarcoma
and ovarian cancer in clinics. Doxil® circulates around the body at a stable state and accumulates in tumor by
passive targeting. Although it is difficult to release doxorubicin after accumulation into the tumor, we made a
new bubble liposomes from Doxil® and investigated the effect on cytotoxicity by combination with this new
Doxil® bubble liposome , encapsulated doxorubicin bubble liposomes(EDBL), and ultrasound in Ca9-22 cells.
The combination of EDBL and ultrasound was found to enhance the cytotoxity of Ca9-22 cells treated by
doxorubicin. These findings suggest that local administration of cytotoxic agents with sonoporation is a useful
method for molecular cancer therapy.
[1] K Iwanaga, K Tominaga, K Yamamoto, M Habu, H Maeda, S Akifusa, T Tsujisawa, T Okinaga, J Fukuda,
T Nishihara. Cancer Gene Therapy, 14(2007)354-363.
[2] H Maeda, K Tominaga, K Iwanaga, F Nagao, M Habu, T Tsujisawa, Y Seta, K Toyoshima, J Fukuda, T
Nishihara. J Oral Pathol Med, 38(2009)572-579.