Drug Delivery System Specifically Targeting Tumors and Procedure to Find the Molecular Targets from Gene Expression Profiles

Time March 22, 2010, 09 00 AM

Location Academic Hall of Biological Building

Masaharu Seno

Professor of Nano-Biotechnology

Graduate School of Natural Science and Technology,

Okayama University

Introduction:

Professor Dr. Masaharu Seno, Vice Dean of Faculty of Engineering, Laboratory of Nano-Biotechnology, Department of Medical and Bioengineering Science, Graduate School of Natural Science and Technology, Okayama University. He is a molecular biologist, graduated from the departmenat of Biophysical Engineering, Osaka University in 1981.

He worked for Takeda Chemical Ind., Co., Ltd. In the Central Research Division 1981-1992. He was awarded PhD from Osaka University in 1989 and became an associate professor of the department of Bioengineering Science, Faculty of Engineering, Okayama University 1992-2001. From 1995-1996 and 2000-2001, he worked in the USA as a visiting scientist of National Cancer Institute, National Institutes of Health, Bethesda, MD.

From 2001, he worked in the Graduate School of Natural Science and Technology. Okayama University and became a Professor of Nano-Biotechnology in the department of Medical and Bioengineering Science 2007. He has been a peer reviewer of Long Range Research Initiative, Japan Chemical Industry Association since 2000 and a member of the Advisory Board of Okayam Foundation for Science and Technology since 2009.

In 2002 he started up a venture company of drug delivery system. His enthusiastic contibution to the industrial technology was awarded by honors. Recent years he focused on the Molecular Targeting of Cancer Cells as well as the Screening of Biomarkers. Professor Seno has published more than 150 papers in most famous journals, such as Nature Biotechnology, Cancer Research, Bimaterials, Nucleic Acids Research, Journal of Biological Chemistry, Molecular and Cellular Biology, Biochemistry, Journal of Molecular Biology, Endocrinology, Cellular Signalling and so on.

Abstract:

I. Efficient cisplatin loading and targeting E-selectin

In our recent study, cisplatin was efficiently encapsulated into the Sialyl LewisX liposomes through novel and simple chemical strategy. Cis-diamminedichloroplatinum (II) known as cisplatin or CDDP is one of the effective agents used for the treatment of wide variety of tumors. However, significant insolubility in water of cisplatin has limited the efficiency of encapsulation into liposomes as well as of method of administration.

Amongst many platinum complexes with ammine ligands in cis location, cis-diamminedinitrato-platinum (CDDP3) is highly soluble in water and easily converts to cisplatin in the presence of chloride ions. Exploiting this character, CDDP3 was encapsulated into liposomes in the absence of chloride ions and then chloride ions were supplemented to form cisplatin in the liposomes.

Finally, nearly three hundred times more amount of cisplatin was encapsulated in the liposomes than that achieved by conventional method. This cisplatin-liposome showed excellent stability during the long-term storage. To deliver the liposomes to tumors Sialyl LewisX was conjugated to the surface of liposomes as the ligand to E-selectin, which has been shown to be a potential target for the drug delivery to tumor in vivo.

Even when cisplatin was administrated at the lethal level as itself, encapsulation in liposomes showed the survival rate of 75 % at 14 days after administration. Although the body weight decreased for 3 days after administration, it recovered after 4 days. No histological abnormality in the organs was found 3 days after administration.

In mice bearing Ehrlich ascites tumors, enhanced the accumulation of cisplatin in the tumor six fold more than the treatment without Sialyl LewisX. Finally, the antitumor activity of cisplatin-liposomes was successfully demonstrated in mice bearing human lung cancer A549 cells suggesting the significant targeting potential of E-selectin induced on the endothelial cells in tumor region.

II. Procedure to find the molecular targets

As demonstrated in the targeting E-selectin, the molecular information on the surface of tumor cells is quite useful for the efficient delivery of anti-cancer agents. If tumor specific cell surface proteins are identified, the procedure of identification should be a great help for cancer therapy. Nowadays DNA microarray is a powerful tool to analyze gene expression profiles.

However, huge amount of information obtained from one experiment is not always easy to comprehensively characterize target cells or tissues. To evaluate and analyze microarray data, we have been proposing the application of spherical self-organizing map (sSOM) as a clustering method. To detect the cell surface markers that are specific to brain tumor, we analyzed gene expression profiles of nine human brain tumor cell lines and normal brain tissues by a DNA microarray, of which 1,795 oligonucleotide probes are originally designed to hybridize to the cDNAs coding only human cell surface proteins.

First of all, the signal data were filtered with the average values and standard deviations and the genes, of which expression was potentially and significantly different between the two groups, were picked up and forwarded to the analysis by sSOM for clustering. As the result, we successfully identified some genes whose expression is significantly consistent in all cancer cell lines analyzed and is higher than those in normal brain tissue.

Clustering was further applied to compare the distances between the cell lines and normal tissues. The relative distances were successfully calculated to classify the cells and tissues to find the separate groups even in the carcinoma derived cell lines. Our cell surface marker DNA microarray should be useful for screening the candidates of cell type-specific surface markers, which might serve as molecular targets for diagnosis and treatment of disease.

The normalized data set was clustered and visualized by sSOM software. The numbers correspond to identity of the genes analyzed. Each position of genes is fixed on the global surface. The colors indicate the expression level for each gene. Red, high; yellow, slightly high; white, median; light blue, slightly low; deep blue, low. See text for the names of cell lines.

Contact: Zongbao Zhao 4712