SUMMARY REPORTS OF EXCHANGE SCIENTISTS

(1) Takao Yamori
Japanese Foundation for Cancer Research

SPONSOR AND HOST INSTITUTION:
Dr. Robert Shoemaker, National Cancer Institute
DATE OF VISIT: October 15 - November 2, 1990

SUMMARY OF ACTIVITIES
I visited the United States on the above date in order to collect information on the development of a new anticancer drug screening system.
First, I visited Dr. Shoemaker at the Frederick Cancer Research and Development Center, NCI, and learned the methods involved in the current disease-oriented anticancer drug screen (DOS). The DOS was initiated by the NCI in 1985 instead of the in vivo P388 leukemia screen. The main purpose for the DOS is to identify entirely new candidate antitumor agents. Each sample is examined for their growth inhibitory activity or cytotoxicity against 60 human cancer cell lines including eight different major cancer types by efficient colorimetric determination using a new protein binding dye (SRB). The most remarkable characteristic of the DOS is its computerized data analysis. Based on the growth inhibition parameters of each compound (GI50), a so-called "finger print" is drawn. The "finger print" is quite interesting and impressive. It clearly shows the disease oriented growth inhibitory activity of the compound. It has been shown that "finger prints" of a certain group of drugs (e.g. DNA binders) show remarkable similarities. Therefore one can possibly predict the mode of action of a tested compound by comparing its "finger print" with those of known anticancer drugs. It is further expected that a compound showing a unique "finger print" which is not comparable to anyone in the data base could have an entirely new mechanism of action. The primary screening laboratory is currently capable of testing compounds at a rate of 400 per week against a 60-line panel. The compound selected by the DOS are next examined in the nude mice transplanted with the appropriate sensitive cancer lines, then, promising compounds will be clinically tested in a disease-oriented manner. However, as the in vivo examination is just underway, it seems to take some more years to evaluate the DOS. In our laboratory, we have been doing an in vitro drug sensitivity test by using several lines of stomach cancer, which has a high incidence in Japan, and now we intend to introduce additionally colon cancer lines. Therefore, it is a great advantage for me to have learned the methodology of the DOS.
After NCI, I visited Dr. Nicolson at M. D. Anderson Cancer Center and Dr. Takada at Research Institute of Scripps Clinic to discuss the current study on the molecular mechanism of cancer metastasis. Topics in Dr. Nicolson's laboratory are a lung-derived growth factor and heparanase gene. They have recently purified from the porcine lung a transferrin-like growth factor which facilitates the proliferation of lung-metastasizing melanoma cells. They are also cloing the gene of heparanase which is involved in tumor invasion. Dr. Takada in Scripps is studying the cell adhesion mechanism by analyzing the structure and function of the integrins, cell surface receptors of adhesion molecules. Recently, he and his colleague have started to investigate the involvement of @B1 subfamily molecules of integrins in the metastatic process by gene transfection. These studies represent the identification of specific molecules determining certain stages of metastasis. It seems very important to develop antimetastatic compounds targeted against such specific molecules.
This visit was quite informative. Especially, the discussions with the various scientists I met was exciting and I have received a lot of suggestions for my research.



(2) Kazuo Umezawa
Keio University

SPONSOR AND HOST INSTITUTION:
Prof. I. H. Krakoff, MD Anderson Cancer Center
DATE OF VISIT: September 15 - October 3, 1990

Summary of Activities
In Prof. Hanafusa's laboratory, Rockfeller University, I introduced our small molecular weight tyrosine kinase inhibitors. We recently found that a tyrosine kinase inhibitor induced normal phenotypes in src-transformed cells, but it was difficult to assay intracellular tyrosine phosphorylation. I learned in his laboratory that it can be assayed by Western blotting followed by anti-phosphotyrosine antibody staining. Then, we discussed importance of protein-protein interaction in the mechanism of signal transduction. From his recent observation, he emphasized the importance of the SH2 and SH3 regions commonly found in src and crk proteins, phospholipase C and PI kinase for the protein-protein interaction. Rockfeller University is only for graduate students, and we discussed on the education of graduate students involved in cancer research in USA and in Japan.
In the Grace Cancer Drug Center, RPCI, I visited Dr. Mihich, and we discussed the possibility of oncogene function inhibitors as future antitumor drugs. After that I gave a lecture on "Oncogene function inhibitors of microbial origin" introducing our recent works. In the Center, they are doing both fundamental cancer research and estimation of new anticancer drugs. I found they developed sophisticated in vitro assay system for anticancer. In the Center, they are doing both fundamental cancer research and estimation of new anticancer drugs. I found they developed sophisticated in vitro assay system for anticancer activity and we discussed our future collaboration in the development of oncogene function inhibitors. I could have interviews to about ten senior researchers in the Center. I discussed the effect of our inhibitors on differentiation in various experimental systems with Dr. Ip and Dr. Bloch.
At MD Anderson Cancer Center I visited Prof. Krakoff, and we discussed on the future development of our oncogene function inhibitors. He also showed me around his department of medicine and I was impressed by the efficient system for drug infusion to visiting cancer patients. At MD Anderson, again I met about ten senior researchers separately. According to our discussion, I am collaborating with Dr. Lopez on encapsulation of erbstatin, a tyrosine kinase inhibitor, in liposomes. Dr. Aaringhaus has asked me for one of our oncogene function inhibitors, and with that we are going to collaborate in the mechanistic study of abl. It is most important that Dr. Siciliano and Prof. Krakoff are glad to send us MDA468 and DiFi cell lines which contain abundant EGF receptors. We are collaborating with these cell lines on the mechanistic study of signal transduction.
In Dr. Hunter's laboratory, the Salk Institute, I learned about particularly useful cell lines for our mechanistic studies of oncogenes. Temperature-sensitive (ts) oncogene transformed cell lines are very suitable for our study and he agreed to send us ts-fps-transformed cells. He also introduced me to Dr. Wang in UCSD, who developed ts-abl transformed cells. I visited her in UCSD, and she agreed to begin collaboration with those cells.
Taken together, the 19 days visit to USA was extremely fruitful for the progress of our research. We began various collaborating works with USA researchers on the use of oncogene function inhibitors.
I feel that if the exchange program is extended to graduate students involved in cancer research, it would Shed more light on cancer research in future.



(3) Michihiko Kuwano
Oita Medical School

SPONSOR AND HOST INSTITUTION:
St. Jude Children's Research Hospital, and NCI, NIH
DATES OF VISIT: December 1-20, 1990

SUMMARY OF ACTIVITIES:
At St. Jude Children's Research Hospital, Memphis, I visited Dr. W. Beck at Pharmacology Department and other scientists. I gave a seminar entitled, "Regulation of multiple drug-resistance (MDR)-1gene expression and development of MDR-reversal agents." We discussed,
(1) Molecular mechanisms for acquirements of various drug- resistances to etoposide, nitrosoureas, and 5-fluorouracil.
(2) Function of gp170 and development of MDR-reversal agents. Concerning MDR-reversal agents, phenoxazine type compounds and verapamil analogs with less calcium antagonism were studied. In particular, we had a strong belief that DNA topoisomerases should be one of most important target for cancer chemotherapy that we should study.
In NCI, NIH, Bethesda and Frederick, I visited Dr. T. Fojo and other scientists. My seminar title was "MDR-1 gene regulation under environmental stresses." We discussed,
(1) Molecular mechanisms for regulation of MDR-1 gene as well as glutathione-S-transferase genes in relation with acquirement of drug-resistance.
(2) Possible correlation of differentiation, environmental stresses and tissue or organ specificity with MDR-1 gene expression.
(3) Establishment of transgenic mice with MDR-1-plus bone marrow proposes very useful screening system for MDR-reversal agents in vivo. In particular, we decided to do a collaboration study with Dr. Fojo, "How expression of MDR-1 gene was controlled in colon cell lines which had various levels of gp70 expression."
(4) How receptors of growth factors including EGF were involved in malignant transformation by tyrosine kinase-related oncogenes.

References
1. Beck, W. T. (1990) Strategies to circumvent multidrug resistance due to P-glycoprotein or to altered DNA topoisomerase II Bull Cancer, 77:1131-1141.
2. Belt, J. A. and Noel, D. (1988) Isolation and characterization of a mutant of L1210 murine leukemia deficient in nitrobenzylthioinosine-insensitive nucleoside transport. J.Bio 1.Chem., 263:13819-13822.
3. Bates, S. E., Mickley, L. A., Chen, Y., Richert, N., Rudick, J., Biedler, J. L. and Fojo, A T. (1989) Expression of a drug resistance gene in human neuroblastoma cell lines: modulation by retinoic acid-induced differentiation. Molec. Cell.Biol., 9:4337-4344.
4. Chin, K-V., Chauhan, S. S., Pastan, I. and Gottesman, M. M. (1990) Regulation of mdr RNA levels in response to cytotoxic drugs in rodent cells. Cell Growth Diff., 1:361-365.
5. Kohno, K., Sato, S., Uchiumi, T., Takano, H., Kato, S. and Kuwano, M. (1990) Tissue-specific enhancer of the human multidrug-resistance (MDR1) gene. J.Bio1.Chem., 265:19690-19696.