Growth regulation by estradiol, progesterone and recombinant human epidermal growth factor of human breast carcinoma xenografts grown serially in nude mice.

Four human breast carcinoma xenografts, MCF-7, Br-10, T-61 and MX-1, were transplanted into female nude mice with or without pretreatment with estradiol and progesterone. Hormone receptors including cytosol and nuclear estrogen receptor (ERc and ERn) and progesterone receptor (PgR) were assessed by the dextran-coated charcoal method and exchange assay; epidermal growth factor receptor (EGFR) was measured by the 125I-EGF binding assay. MCF-7 and T-61 were ERc-, ERn- and PgR- positive, but Br-10 was positive only for ERc; MX-1 was negative for these hormone receptors, but was the only xenograft showing EGFR. The growth of MCF-7 and Br-10 was enhanced by exogenous estradiol and progesterone, whereas the growth of T-61 was markedly inhibited by exogenous estradiol; the growth of MX-1 was not influenced by these sex steroids. Recombinant human epidermal growth factor (rhEGF) inhibited the growth of EGFR-positive MX-1 dose-dependently, whereas no changes were observed in the growth of EGFR-negative MCF-7, Br-10 and T-61 after treatment with rhEGF. This paradoxical inhibition of rhEGF on EGFR-positive MX-1 might be due to down-regulation of EGFR, as shown in the ER-positive xenograft T-61, whose growth was inhibited by estradiol.

Recombinant human interferon-alpha 2a increases hormone receptor level of a human breast carcinoma xenograft in nude mice and enhances the anti-proliferative activity of tamoxifen.

The effect of recombinant human interferon-alpha 2a (rhIFN-alpha 2a) on the hormone receptor level and antitumor activity of tamoxifen (TAM) was investigated in nude mice using ZR-75-1, an estrogen receptor (ER)-positive, and progesterone receptor (PgR)-negative human breast carcinoma xenograft. ER levels (maximum binding sites) of tumors treated with rhIFN-alpha 2a at a dose of 6 x 10(5) U/mouse/day for 1 or 3 wk were not significantly different from the control, whereas those with rhIFN-alpha 2a at a dose of 6 x 10(4) U/mouse/day for 1 or 3 wk were higher than the control (3.9- to 4.4-fold) with a significant difference at P < 0.01. The increase of ER by rhIFN-alpha 2a was investigated using a sucrose density gradient method. The peak was only seen at 8S in both rhIFN-alpha 2a-treated tumor and control ER, and the sedimentation patterns were almost the same, suggesting that both ERs were essentially equivalent. On the other hand, PgR of all the treated groups could be detected, while that of the control group was undetectable. The antitumor effect of the combination treatment of rhIFN-alpha 2a and TAM was compared with those of single treatments. While rhIFN-alpha 2a at a dose of 6 x 10(5) U/mouse/day and TAM did not show a combination effect, rhIFN-alpha 2a at a dose of 6 x 10(4) U/mouse/day and TAM showed a synergistic combination effect, and ER was decreased to the threshold of detection by the combination treatment. These findings indicated that a low dose of rhIFN-alpha 2a increased the ER levels of ER-positive human breast cancer in vivo as well as in vitro and enhanced the anti-proliferative effect of TAM, and the newly synthesized ER was essentially the same as the original ER.

[Antitumor activity and toxicity of KB-5424 R, a newly developed antitumor platinum compound].

KB-5424 (ab-(3-aminopyrrolidine)-cd-[glycolato (2-)-0, 0'] platinum (II) is a newly developed antitumor platinum compound which was synthesized at Kanebo Institute for Cancer Research. When the antitumor activity of KB-5424 was evaluated using several rodent tumors, no significant differences were observed between the antitumor activities of KB-5424, cisplatin (CDDP) and DWA-2114 R (DWA). KB-5424 was divided into two kinds of optical isomers, KB-5424 R and KB-5424 S, of which antitumor activity was compared each other. The maximum increased life span (ILSmax) on L 1210 of KB-5424 R was almost equal to that of CDDP and better than those of KB-5424 S and carboplatin (CBDCA). The antitumor activity of KB-5424 R on a human tumor xenograft MX-1 was almost identical to those of CDDP and CBDCA and better than that of DWA. Since the nephrotoxicity of KB-5424 R was significantly reduced comparing with CDDP, this newly developed antitumor platinum compound was thought to be a promising agent for the clinical application.

Antitumor activity of fluoropyrimidines and thymidylate synthetase inhibition.

Experimental chemotherapy with 5-fluorouracil (5-FU; 60 mg/kg), 1-hexylcarbamoyl-5-fluorouracil (HCFU; 70 mg/kg), 3-(3-(6-benzoyloxy-3-cyano-2-pyridyloxycarbonyl)benzoyl)-1-ethoxym ethyl-5- fluorouracil (BOF-A2; 30 mg/kg) and UFT (20 mg/kg as tegafur with uracil at a molar ratio of 1:4) was performed using human gastric (H-111) and colon (Co-4) carcinoma strains in nude mice. 5-FU was administered ip with a q4d x 3 schedule and the other agents were given po daily for three weeks. Concentrations of 5-FU in the serum and the tumor were assessed by gas chromatography-mass fragmentography, two hours or 12 days (5-FU) after the last treatment, and thymidylate synthetase (TS) was assayed according to the method of Spears et al. using the same schedule. The antitumor activity of the agents was assessed in terms of the actual tumor weight at the end of the experiment. HCFU was effective against both strains and 5-FU was effective against Co-4, although the other agents were ineffective against either strain. Statistically significant correlations were found between the serum and tumor concentrations of 5-FU and antitumor activity. Statistically significant correlations were also observed between the antitumor activity and TS inhibition rate (TSIR) and the activity of free thymidylate synthetase (TSfree), with higher TSIR and lower TSfree resulting in higher antitumor activity. Therefore, TSIR and TSfree were thought to be promising indicators for predicting the antitumor activity of fluoropyrimidines.

[Experimental combined chemo- and endocrine therapy with UFT and tamoxifen in human breast carcinoma xenografts serially transplanted into nude mice].

We have investigated the experimental combined chemo- and endocrine therapy of UFT and tamoxifen (TAM) on two human breast carcinoma xenografts, R-27 and Br-10 with estrogen receptors (ER) serially transplanted into nude mice. When sc inoculated tumor started the exponential growth, the treatments were initiated in four groups which were control, UFT 20 mg/kg (as tegafur) po daily for 18 times, TAM 5 mg/kg im twice a week for 6 times and UFT + TAM groups. The antitumor activity of the agents were assessed by the growth curves, the lowest T/C ratios of the relative mean tumor weight and the actual tumor weights at the end of the experiments. TAM alone was effective on both R-27 and ineffective on Br-10, while UFT alone was ineffective on R-27 and Br-10. The combination antitumor activity was observed in R-27 but not in Br-10. When 5 mg of TAM per kg and 20 mg of UFT per kg as tegafur was administered daily po for 2 wk, there were no statistically significant differences between the concentration of 5-FU in UFT alone and UFT + TAM groups for the two strains. By the assay of ER and progesterone receptors using the same specimen, it was observed that ER was stable by the treatment of UFT, while ER was suppressed by the treatment of TAM in both tumor strains. In addition, this suppression of ER by TAM alone was enhanced by the combined treatment with UFT in both the strains.(ABSTRACT TRUNCATED AT 250 WORDS)

Antitumor activity and pharmacokinetics of a morpholino-anthracycline derivative (KRN8602) against human breast carcinoma xenografts serially transplanted into nude mice.

The antitumor activity and pharmacokinetics of (7R, 8S, 10S)-10-((3-deamino- 3-(4-morpholino)-2,3,6-trideoxy-alpha-L-lyxo-hexopyranosyl)oxy)-8- ethyl- 7,8,9,10-tetrahydro-1,6,7,8,11-pentahydroxy-5,12-naphthacenedione hydrochloride (KRN8602) were evaluated using five human breast carcinoma xenografts in nude mice. The maximum non-toxic dose of KRN8602 was 2 mg/kg by q4d x 3 intraperitoneal and peroral administration. KRN8602 showed significant antitumor activity against MX-1, which is less sensitive to adriamycin, with the chemotherapeutic indices of 13.0 for po administration and 9.5 for ip injection. Although KRN8602 also inhibited the growth of T-61 significantly, the antitumor activity of this agent against the other three breast carcinoma xenografts was limited. To elucidate this discrepancy, pharmacokinetic analysis and MTT assay were conducted using the KRN8602-sensitive MX-1 and KRN8602-insensitive R-27. While no differences were observed in the area under the curve and the peak concentration of KRN8602 for each tumor, a difference in the sensitivity of the tumor strains was obvious in MTT assay. The efficacy of this agent seemed to depend on the sensitivity of each type of tumor cell rather than the concentration of agent in tumor tissues. If it were possible to select patients with sensitive tumor cells to this agent by the MTT assay, the phase II trial might be completed within a short period by reducing the number of studied patients.

[Enhancement of antitumor activity of mitomycin C against human breast carcinoma xenografts by pretreatment with KM 2210].

Three human breast carcinoma xenografts, MCF-7, R-27 and T-61 serially transplanted into nude mice were treated with mitomycin C (MMC) alone, KM2210 (estra-1, 3, 5(10)-triene-3, 17 beta-diol, 3 benzoate 17-[4-(4-bis(2-chloroethyl)amino)phenyl)-1-oxobutoxy)acetate) alone and KM2210 followed by MMC. One hundred or 300 mg of KM2210 per kg were administered orally daily from Day 1 to 4 and MMC at the dose of 3 mg/kg was given ip on Day 5. The antitumor activity of MMC on these xenografts was enhanced by pretreatment with KM2210, suggesting a new combination chemo- and endocrine therapy of hormone-dependent human breast carcinomas.