[The effect of cis-platinum (CDDP) on methotrexate-resistant choriocarcinoma cell line]

Cis-platinum (CDDP) was investigated in vitro and in vivo for its ability to inhibit the growth of Methotrexate (MTX)-resistant choriocarcinoma cell line (BeWo) and was compared with the effect of MTX and Actinomycin D (ACD). Each drug was added into medium (RPMI 1640 containing 10% FBS) for 1 hr. at the concentration of peak plasma level in clinical use (CDDP 7 X 10(-6)M, MTX 10(-6)M, and ACD 8 X 10(-8)M), or for 48 hrs. at one-tenth of the level. CDDP inhibited the cell growth to 40% of control at 7 X 10(-6)M for 1 hr., and 25% at 7 X 10(-7) M for 48 hrs. And ACD suppressed the cell growth to 10% at both 8 X 10(-8)M for 1 hr. and 8 X 10(-9)M for 48 hrs. But MTX did not inhibit the cell growth at 10(-6)M for 1 hr., and inhibited to 60% of control at 10(-7)M for 48 hrs. On the other hand, BeWo transplanted to athymic nude mice (CD-1(ICR) nu/nu) was treated with intraperitoneal injections of CDDP (1.4 mg/kg/day for 4 consecutive days in a week and repeated for 2 and 4 weeks), MTX (2mg/kg/day for 4 consecutive days in a week and repeated for 2 weeks), and ACD (90 micrograms/kg/day for 4 consecutive days in a week and repeated for 2 and 4 weeks). The suppression of the tumor growth was seen in CDDP-treated group (TRW/CRW = 6.5%) and ACD-treated group (TRW/CRW = 29%) after 2 courses of treatment, but no apparent suppression was shown in the MTX-treated group.(ABSTRACT TRUNCATED AT 250 WORDS)