Induction of thymidylate synthase associated with multidrug resistance in human breast and colon cancer cell lines.

摘要: A series of Adriamycin-resistant human breast MCF-7 and colon DLD-1 cancer cell lines were established by stepwise selection. The concentration Adriamycin required to inhibit proliferation 50% (IC50) in the parent line (MCF-7), (MCF-Ad5 MCF-Ad10), a 5-fluorouracil (5-FU)-revertant (MCF-R) was 0.005, 3.3, 6, 4.9 microM, respectively. IC50 value for resistant (DLD-Ad) 8.2 68-fold higher than that its (DLD-1) (IC50 = 0.12 microM). MCF-Ad5 MCF-Ad10 cells cross-resistant 5-FU, with respective 5-FU values 11.7 22.5 or 7.3- 14-fold less sensitive their 1.6 microM) line. MCF-R completely reverted sensitivity an 1.7 microM. DLD-Ad 3.5-fold more Using both 5-fluoro-2'-deoxyuridine-5'-monophosphate binding catalytic assays measurement thymidylate synthase (TS) activity, there significantly increased TS activity (2.4- 2.5-fold), (11.5- 6.8-fold), (4.8- 10.7-fold) lines, assays, respectively, compared lines. level cytosolic extracts, as determined Western immunoblot analysis, markedly (31-fold), (46-fold), (52-fold) cells. Measurement mRNA levels Northern analysis revealed elevation MCF-AD5 (16.7-fold), (55-fold) Southern showed this increase not accompanied any major rearrangements amplification gene. Incorporation into RNA DNA different, These studies suggest exposure leads overexpression TS, concomitant development resistance 5-FU.