Antitumor efficacy of PD115934 (NSC 366140) against solid tumors of mice

PD115934 (NSC 366140) is a soluble pyrazoloacridine derivative presently undergoing preclinical toxicology evaluation with the anticipation of Phase I human investigation. The agent displayed both human and murine solid tumor selectivity in vitro in a soft agar disk diffusion assay, relative to its activity against murine L1210 leukemia. In vivo it was highly active against solid tumors colon adenocarcinoma 38 and pancreas ductal carcinoma 03, which was consistent with the cellular cytotoxicity seen in the disk diffusion assay. A log cell kill of greater than 4.0 was demonstrated in vivo against both models. PD115934 was administered by both bolus and infusional therapy. After completion of these trials, it was determined that this compound was a schedule category III agent, i.e., a schedule-independent agent with peak plasma level toxicity. The main toxicity encountered with infusional therapy was myelosuppression. With bolus therapy, central nervous system toxicities were dose limiting. On the basis of our preclinical infusion studies, we recommend a 2-h infusion twice weekly in humans in order to obtain a total dose of 360 mg/m2 over 8 weeks.     

Selection and characterization of L1210 sublines resistant to teniposide (VM-26)

Two spectra of L1210 sublines with gradations of resistance to teniposide (VM-26) were selected by stepwise exposure of cultures to increasing concentrations of the drug. Cultures representing the first spectrum were from 20 times to 1200 times more resistant to VM-26 than were cultures of parental cells. At 24 hr after addition of 22 nM VM-26 to the medium, the growth of cultures of parental cells was inhibited by 50%. Increases in resistance to VM-26 among the sublines coincided with increases in population doubling times. When cells were transferred to drug-free medium, there was a sharp decrease in resistance over the first 10 days; the subsequent decline in resistance, over 2 to 4 months, correlated with a decrease in population doubling times. The second spectrum of resistant sublines arose from the first spectrum after the latter had been maintained for about 1 year on various selective concentrations of VM-26. Resistance to VM-26 by this second group of sublines was from 400 times to over 2000 times greater than that of the parental cell line. Doubling times for these resistant cell populations were similar to the normal rate of the parental cell line. Eight sublines were characterized by two chromosomes with homogeneously staining regions, while the remaining subline had a single chromosome with this anomaly. One of the regions appeared on a submetacentric chromosome in seven of the nine sublines, while the other was on an acrocentric chromosome. These observations indicate that a longer doubling time facilitated selection of increasingly resistant sublines but was not essential for the resistance of sublines in the second spectrum.     

Enhancement of adriamycin cytotoxicity in sensitive and resistant sublines of human tumor cells by calcium antagonists

The effect of the calcium antagonists cepharanthine and verapamil on adriamycin-induced cytotoxicity against sensitive (K 562 and Ov 2780) and resistant (K 562/ADM and AD 10) sublines of human tumor cells was evaluated. Nontoxic concentrations of cepharanthine moderately enhanced adriamycin cytotoxicity against sensitive sublines (2.1-2.5 fold). A significant enhancement (13-26 fold) of drug cytotoxicity was observed when resistant cells were treated with a combination of cepharanthine and adriamycin. The calcium influx blocker verapamil (used for comparison) also enhanced adriamycin cytotoxicity, although to a lesser extent. The fact that enhancement was 6-10 fold greater in resistant then in sensitive cells, as well as the loss of biphasic properties of adriamycin on dose-response curves after combined treatment, indicate that cepharanthine may play a role in overcoming drug resistance in some tumor cells.     

Antitumor effect of Sarcophaga lectin on murine transplanted tumors

Sarcophaga lectin, a lectin purified from the hemolymph of Sarcophaga peregrina (flesh fly) larvae, was found to be therapeutically effective against both ascitic and solid tumors. It was especially effective when injected directly into or around nodules of the syngeneic tumor Meth A transplanted intradermally into BALB/c mice. It also induced cytotoxic activity against L-929 cells when it was added to the culture medium of macrophages in vitro. Similar cytotoxic activity was detected transiently in the serum when it was injected into the abdominal cavity of mice, in which sarcoma 180 cells had been inoculated. Probably, this cytotoxic activity induced by Sarcophaga lectin partly contributes to the elimination of tumors. The possible role of this cytotoxic activity is discussed from the viewpoint of ontogeny.     

Antitumor activity of thaliblastine (NSC-68075) in experimental ovarian tumor cell lines sensitive and resistant to cisplatin.

Cytotoxicity of thaliblastine (thalicarpine, TBL; NSC-68075) and/or cisplatin (DDP) in DDP-sensitive (O-342) and-resistant (O-342/DDP) rat ovarian tumor cell lines was comparatively determined using the MTT assay. The 50% inhibitory dose (ID50) of DDP was found to be 6.2 microM in O-342 cells and 23.4 microM in O-342/DDP cells, while, vice versa, the ID50 of TBL was 39.3 micrograms/ml in the sensitive line and 27.3 micrograms/ml in the resistant line. Furthermore, simultaneous exposure of cells to DDP and TBL showed a significant superiority over DDP alone in O-342 cells, as evaluated with variance analysis (P less than 0.001). This enhancing effect of TBL on DDP cytotoxicity, however, was not observed in the resistant cells.     

Antitumor effect of actinidia chinensis polysaccharide on murine tumor

A new polysaccharide compound (ACPS-R) has recently been isolated from the root of Actinidia Chinensis Planch. When given intraperitoneally to the transplantable tumor bearing mice at dose of 75-125 mg/kg, the tumor inhibition rate was more than 88.8% in Ehrilich ascitic cancer (EAC) or ascitic form of hepatoma (HepA) and more than 49.6% in solid hepatoma (HepS). The treatment effect of ACPS-R on EAC at dose of 15 mg/kg and 22.5 mg/kg, respectively. ACPS-R could also prolong the life of EAC-or P388-bearing mice, and increase the percentage of EAC-free mice. In addition, when ACPS-R was used in combination with 5-Fu, the antitumor effect was enhanced as compared with 5-Fu alone. A marked increase in cAMP levels and cAMP/cGMP ratio of spleen of EAC-bearing mice were observed after treatment of ACPS-R. The increase of both parameters nearly reached the normal levels of healthy mice. The increases of cAMP, cAMP/cGMP and tumor remission had statistical significance. It showed an intermediate inhibitory effect of ACPS-R on DNA synthesis by incorporating 3H-TdR into EAC cells. The results indicated that ACPS-R acts as a new antitumor polysaccharide, and the treatment effect of Actinidia root in folk medicine is probably related to ACPS-R.     

Differential effect of clofibrate on adriamycin cytotoxicity in P388 murine leukemia cells sensitive and resistant to adriamycin

Clofibrate (CPIB), an antihyperlipidemic agent, was utilized as a drug response modulator to modify the cytotoxicity of adriamycin (ADR) in vitro in P388 murine lymphocytic leukemia cells sensitive (P388/S) and resistant (P388/ADR) to ADR. CPIB elicited concentration and time dependent DNA biosynthesis inhibition which was completely reversible up to the concentration of 0.0025% in P388/S. However, only a partial reversibility of DNA biosynthesis inhibition was observed in P388/ADR cells treated with 0.0025% of CPIB. In both P388/S and P388/ADR there was complete and irreversible DNA biosynthesis inhibition at CPIB concentration of 0.005%. These findings were further confirmed by tumorigenicity analysis. CPIB was ineffective in altering ADR cytotoxicity in P388/S cells. However, in P388/ADR, CPIB enhanced ADR cytotoxicity at the lower concentrations of ADR and decreased the cytotoxicity upon increase in ADR concentrations. The enhancement in ADR cytotoxicity by CPIB in P388/ADR was due to increased ADR accumulation which was absent in P388/S cells. The present findings suggest the utility of CPIB as a selective agent to circumvent ADR resistance and to reduce host toxicity due to the drug.     

Evaluation of trans-tetrachloro-1,2-diaminocyclohexane platinum (IV) in murine leukemia L1210 resistant and sensitive to cis-diamminedichloroplatinum (II)

Summary trans-Tetrachloro-1,2-diaminocyclohexane platinum (IV) (tetraplatin) was therapeutically effective in mice bearing leukemia L1210 resistant (L1210/DDPt) or sensitive (L1210/0) to cis-diamminedichloroplatinum (II) (cisplatin). Furthermore, the sensitivity of cultured L1210/DDPt and L1210/0 cell populations to tetraplatin, cisplatin, and dichloro-trans-dihydroxyisopropylamine platinum (IV) (CHIP) was a function of the concentrations used for each compound. The relative degree of sensitivity between cultured L1210/DDPt and L1210/0 cells for each compound on the basis of the LC₉₉ (the concentration of each compound required to reduce the number of viable cells by 99% in each cell line) was 3-fold for cisplatin, 2-fold for tetraplatin, and 3-fold for CHIP; thus the cultured L1210/0 cells exhibited a greater degree of sensitivity than the L1210/DDPt cells to the platinum compounds. The data indicate that of reduction of platinum IV compounds to platinum II compounds or metabolites is required for antitumor activity, then the cultured L1210 cells are capable of this bioreduction independently of any host factors.This work was supported by Contract N01-CM-47580 with the Division of Cancer Treatment, National Cancer Institute, Bethesda, MD 20892Mrs Mary W. Trader died on January 16, 1987     

Cellular pharmacology in murine and human leukemic cell lines of diaziquone (NSC 182986)

We investigated the in vitro interaction with and antitumor effect on several murine and human leukemic cell lines of diaziquone (AZQ). L1210 cells accumulated AZQ from Roswell Park Memorial Institute Medium 1640 with or without newborn calf serum by a temperature-dependent and sodium azide-resistant process. AZQ inhibited, in a dose-dependent fashion, [3H]thymidine incorporation into L1210 cells, but this inhibition was slow to develop, requiring approximately 6 hr to become apparent. The minimal inhibitory concentration of AZQ for this process was 0.05 to 0.25 nmol/ml. AZQ was a much less effective inhibitor of L1210 cell [3H]uridine and [14C]valine incorporation. In suspension cultures, AZQ inhibited growth of L1210 and HL-60 cells at minimal inhibitory concentrations of 0.5 to 1 nmol/ml. In soft agar cultures, AZQ inhibited HL-60 cell cloning at minimal inhibitory concentrations of 0.1 to 0.3 nmol/ml. AZQ provoked a dose-dependent increase in oxygen consumption when added to intact L1210, HL-60, and K562 cells and was converted to an AZQ anion free radical by these cells. When the aziridine rings of AZQ were opened by acid treatment, the resulting molecule was not accumulated by L1210 cells, did not provoke O2 consumption, did not form free radicals when added to L1210 cells, and was a much less effective inhibitor of [3H]thymidine incorporation by L1210 cells than was AZQ.     

Antitumor effect of arsenic trioxide in murine xenograft model

Arsenic trioxide, As₂O₃ (ATO), has been established to be an effective agent for treating acute promyelocytic leukemia, but its effect on solid tumors has not been fully explored. In the present study in a murine xenograft system, we found that ATO significantly inhibited tumor growth of the inoculated human hepatocellular carcinoma cell line HuH7 when administered either intravenously or intratumorally. Pathological examination revealed that ATO induced extensive cell death in the tumor. Some of the dead cells in intratumorally ATO-treated mice showed characteristic features of apoptosis, such as nuclear condensation and fragmentation, and were TUNEL-positive. The measurement of arsenic by using particle induced X-ray emission revealed that arsenic was accumulated more in the tumor than in brain, kidney or liver after the intravenous injection of ATO, which is consistent with the hemorrhagic cell death observed in ATO-treated tumor tissues. Thus, ATO appears to have potential for the treatment of solid tumors, as well as hematopoietic malignancies.     

Antitumor activity of 2-chloroethyl (methylsulfonyl)methanesulfonate (clomesone, NSC 33847) against selected tumor systems in mice

Clomesone was evaluated for antitumor activity against a spectrum of animal tumor models. Clomesone exhibited significant antitumor activity against the murine L1210 leukemia implanted i.p., s.c., and intracerebrally (i.c.). Activity against s.c.-implanted tumor was largely independent of schedule and route of administration. Therapeutically optimal single-dose treatment (for tumored mice) was less toxic to nontumored mice than therapeutically optimal prolonged treatment. Clomesone also exhibited activity against other murine tumors (P388 leukemia, B16 melanoma, Lewis lung carcinoma, and M5076 sarcoma). It was active against P388 leukemia sublines resistant to cyclophosphamide, L-phenylalanine mustard, and cis-diamminedichloroplatinum(II). No activity was observed against a P388 subline resistant to N,N'-bis(2-chloroethyl)-N-nitrosourea or against Ridgway osteogenic sarcoma, a nitrosourea-resistant murine solid tumor. Clomesone is generally as effective as the chloroethylnitrosoureas against experimental tumor models. Since clomesone does not have the hydroxyethylating and carbamoylating activities of the chloroethylnitrosoureas (which do not appear to contribute to antitumor activity), it would likely be a more toxicologically selective compound. It may prove to be less carcinogenic than the chloroethylnitrosoureas, and it may contribute less target organ toxicity and less interference with the actions of other drugs when used in combinations.     

Antitumor activity of amidoximes (hydroxyurea analogs) in murine tumor systems

A series of amidoximes was prepared and evaluated for possible antitumor activity against L1210 leukemia. Three of the most active compounds in the L1210 system, formamidoxime, acetamidoxime, and 2-aminoacetamidoxime hydrochloride, were also active against P388 leukemia. Acetamidoxime was marginally active against Lewis lung carcinoma. The active amidoximes showed best activity against L1210 leukemia when given two times daily, 5 hours apart, for 8 days. Most of the amidoximes produced excessive central nervous system stimulation.     

Cytotoxicity and cellular accumulation of a new cis-diammineplatinum (II) complex containing procaine in murine L1210 cells sensitive and resistant to cis-diamminedichloroplatinum (II)

 The emergence of drug resistance during tumor chemotherapy is one of the main problems associated with cancer treatment, particularly with cisplatin (cis-DDP). In the hope of overcoming this problem, various cis-DDP-derived compounds have been synthesized, and their pharmacological activity was compared with that of cis-DDP. In this paper we report on studies on the cytotoxic activity induced by cis-diamminechloro-[2-(diethylamino)ethyl-4-aminobenzoate, N ⁴]-chlorideplatinum(II) monohydrochloride monohydrate (DPR), a new complex of platinum containing procaine. All experiments were carried out on murine leukemic cells, which were either sensitive (L1210) or resistant (L1210/DDP) to cis-DDP. A tetrazolium dye (MTT) assay conducted 5 days after a 2-h exposure of cells to both drugs was utilized to determine the resistance factor (RF) of L1210/DDP cells as compared with the sensitive wild-type cells. Drug accumulation and efflux, together with the amount of platinum bound to DNA, were also investigated. The activity of DPR on sensitive cells was not significantly different from that of cis-DDP. Conversely, DPR was 4.3 times more effective than cis-DDP on resistant cells. A decreased drug accumulation is one of the mechanisms of resistance to cis-DDP of L1210/DDP cells. However, DPR accumulation was not significantly different in sensitive and resistant L1210 cells. Under culture conditions that yielded similar intracellular platinum concentrations, treatment with DPR produced significantly greater DNA platination than did treatment with cis-DDP in both cell lines. No difference in efflux was observed between L1210 and L1210/DDP cells exposed to either cis-DDP or DPR. Our results show that in parental cells, DPR is as potent as cis-DDP on a molar basis, and it is also minimally cross-resistant with cis-DDP in L1210/DDP cells. A direct implication of our results is that DPR could be useful in those human tumors showing a mechanism of resistance similar to that of L1210/ DDP cells. Received: 11 March 1994/Accepted: 15 July 1994     

Characterization of newly established human myeloid leukemia cell line (KF-19) and its drug resistant sublines

A new human myeloid leukemia cell line, designated KF-19, and its drug resistant sublines have been established. The KF-19 cell line was established from the pericardial effusion of a patient with acute myeloid leukemia clinically resistant to chemotherapy and KF-19 cells were characterized by expression of myeloid markers and differentiation into neutrophil- and macrophage-like cells upon optimal stimulations. KF-19AraC, KF-19ADR and KF-19VCR were established as sublines resistant to cytosine arabinoside (AraC), adriamycin (ADR) and vincristine (VCR), respectively. Efflux of the corresponding drugs was documented in each cell line. Expression of the MDR1 gene and the P-glycoprotein was found only in KF-19ADR, which showed a cross resistance to anthracyclines and vinca alkaloids; this resistance was reversed by verapamil or cyclosporin A. KF-19VCR lacking MDR1 gene and P-glycoprotein expression showed only resistance to vinca alkaloids, which was partially reversed by verapamil and cyclosporin A. Unexpectedly, KF-19ADR and KF-19VCR displayed cross resistance to AraC, despite lack of alterations of deoxycytidine kinase (dCK) and deaminase (dA) activities. KF-19AraC showed an efflux of AraC as well as a decreased level of dCK, but not of dA. In addition, KF-19AraC showed cross resistance to VCR in the efflux assay. The cell lines reported herein will provide new aspects on the mechanisms of drug resistance in leukemic cells.