| Co-Investigator(Kenkyū-buntansha) |
HIRAKAWA Toshio Kyushu Univ. Hospital, Dept. of OB & Gyn, Senior Lecturer, 医学部・附属病院, 講師 (20218770)
SONODA Kenzo Kyushu Univ. Hospital, Dept. of OB & Gyn, Assistant Prof., 医学部・附属病院, 助手 (30294929)
FUKUSHIMA Koutarou Kyushu Univ. Hospital, Dept. of OB & Gyn, Assistant Prof., 医学部・附属病院, 助手 (40304779)
|
|---|
| Budget Amount *help |
¥3,300,000 (Direct Cost: ¥3,300,000)
Fiscal Year 2001: ¥1,600,000 (Direct Cost: ¥1,600,000)
Fiscal Year 2000: ¥1,700,000 (Direct Cost: ¥1,700,000)
|
|---|
| Research Abstract |
In vivo-established alkylating agent-resistant variants of the EMT-6 mouse mammary tumor cell line could express drug resistance only in tumor-bearing animals but not in monolayer cell culture systems (Teicher et al.., Science, 1990). We subsequently demonstrated that these in vivo-established drug-resistant variants could reproduce drug resistance even in vitro, but only when grown as three-dimensional cellular aggregates, and that only the drug-resistant sublines, unlike the drug-sensitive sublines, were capable of forming highly compact cellular spheroids (Kobayashi et al., PNAS, 1993). To detect the genes relevant to the above-mentioned drug resistance mechanism, based on the response of a cell population (i.e. 'multicellular resistance') as opposed to (uni)cellular resistance mechanisms, we used a differential display method and compared the levels of gene expression between drug sensitive and resistant sublines under monolayer or three-dimensional cell culture conditions. Forty-e
… More
ight expression sequence tags, which were highly expressed only in the drug resistant variants grown three-dimensionally, were collected and analyzed. Subsequent RT-PCR analyses, revealed five genes expressed differentially: (1) aldehyde dehydrogenase-3 gene, (2) glutathione S-transferase mu gene, (3) prolyl 4-hydroxylase alpha gene, (4) mouse VL30 retro-element gene, (5) mouse 18S and 28S rRNA, 5'hypervariable (Vr) region gene. Assuming that the cellular architecture of 'compact spheroid' enhances the expression of these genes in in vivo-established drug resistant variants, there is the possibility of a linkage between a tumor cell-tumor cell interaction in multicellular structure and resistance to alkylating agents through controllable gene expression. Another possibility is that the in vivo drug exposure induces/enhances the above-mentioned candidate gene(s) expression at first, and then a subsequent upregulation of gene(s) expression occurs in particular molecule(s) which enables the compact spheroid formation. Ovarian cancer seems to be a good candidate to evaluate these hypothesis because it exists as a spheroid in a patient ascites and further studies are underway. Less
|
