In vitro antitumor activity of MIC2 protein-doxorubicin conjugates

The pseudoautosomal encoded MIC2 glycoprotein is a tumor-associated antigen of Ewing's sarcoma (ES) and closely related tumors of unknown function. To investigate the use of this protein as selective drug carrier recombinant MIC2 was coupled to doxorubicin by a two step glutaraldehyde method (molar ratio DOX/MIC2 of 32 and 16). The conjugates showed dose-dependent cytostatic activity against the ES cell line SK-ES1, the peripheral neuroectodermal line KAL and the prostate cancer cell line PC-3 concurrent with reduced toxicity against normal lymphoblasts. In comparison to free doxorubicin the MIC2-doxorubicin conjugates exhibited highest activity against the PC-3 cell line. Confocal microscopy showed intracellular accumulation of MIC2 conjugates.     

Intrathecal chemotherapy. Selection of cytostatic agents

Selection of cytostatic agents for intrathecal administration is the subject of this paper.     

In vitro antitumor activity of silybin nanosuspension in PC-3 cells

The present study aims to evaluate the antitumor activity of silybin nanosuspension on human prostatic carcinoma PC-3 cell line in vitro. Silybin nanosuspension was prepared by the high pressure homogenization (HPH) method. MTT assay, observation of morphological changes and apoptotic body showed that silybin nanosuspension could significantly enhance the in vitro cytotoxicity against PC-3 cells compared to the silybin solution. Flow cytometric (FCM) analysis demonstrated that silybin nanosuspension induced G1 cycle arrest and apoptosis in PC-3 cells. Thereby, the overall results suggest that the silybin nanosuspension represents a potential source of medicine for the treatment of human prostate cancer.     

In vitro chemosensitivity test with several antitumor agents against eight malignant brain tumor cell-lines

We performed an in vitro chemosensitivity test with 8 malignant brain tumor cell lines, which were established in our Department. It was shown that ACNU was moderately tumoricidal against only one cell (ONS-86) line. IFN-beta (interferon-beta) was more active against 4 cell (ONS-6, -20, -76, and -81) lines. VCR (vincristine), MTX (methotrexate), and Ara-C (cytosine arabinoside) and FK 973 were most effective against all 8 cell lines. There were some difference in the drug sensitivities among the tumors with the same pathological diagnosis. Since IFN-beta was tumoricidal against to the cells, co-culture of IFN-beta and one of other antitumor agents seemed to induce more antitumor effects. With regard to the side effects of IFN-beta, the combined therapy with IFN-beta and other drugs induced more antitumor effects against malignant brain tumor cells and seemed to reduce the side effects.     

Stimulatory effect of staphylococcal leukocidin on granulopoiesis disturbed by cytostatic agents.

Functional tests of granulopoiesis (leukocytosis, bone marrow picture, incubation in vitro of bone marrow with [3H]thymidine followed by radioautography and counting of labeled promyelocytes and myelocytes, serum muramidase level, liberation of granulocyte bone marrow reserve, Nitro-BT reduction in blood granulocytes, enzyme cytochemistry, and phagocytosis) were performed in rabbits given bubulphan (10 mg/kg) or 5-fluorouracil (200 mg/kg). Determinations were carried on serially during treatment with cytostatics. Some of the cytostatic-treated animals received intravenous (i.v.) injections of purified staphylococcal leukocidin in daily doses of 0.1 mg/kg. In control animals, theleukocidin resulted in stimulation of granulopoiesis (leukocytosis, increased number of [3H]thymidine-labeled myelocytes, elevated serum muramidase level). Animals receiving cytostatics suffered from marked inhibition of granulopoiesis accompanied by decrease of bone marrow granulocyte reserve. Injection of staphylococcal leukocidin during the period of myelosuppression evoked by cytostatics resulted in partial protection of granylopoiesis and faster regeneration of the leukocyte system.     

Use of vasoactive agents to increase tumor perfusion and the antitumor efficacy of drug-monoclonal antibody conjugates

The effects of both alpha 1- and beta-adrenergic blocking agents on the vascular perfusion of tumors were studied with the ultimate goal of improving diagnosis and therapy of solid tumors with the use of monoclonal antibody (MAb) conjugates. With the use of a subcutaneously growing murine thymoma, it was demonstrated that nonselective and cardioselective beta-adrenergic blocking agents were capable of increasing threefold tumor-to-blood and tumor-to-liver perfusion of 125I-labeled MAbs. Subsequently, these beta-adrenergic blocking agents were found to increase the antitumor efficacy of idarubicin (Ida)-MAb conjugates. Conjugate-treated mice that also received beta-adrenergic blocking agents had a smaller mean tumor size and a greater number of regressions than mice receiving Ida-MAb conjugate alone. By contrast, prazosin HCl, an alpha 1-adrenergic blocking agent, and Cyclospasmol, a peripheral vasodilator, did not enhance the tumor perfusion and antitumor efficacy of 125I- or Ida-conjugated MAbs, and no vasoactive agent enhanced the antitumor effect of Ida when used alone. By their selective action on normal blood vessels, vasoactive drugs can change the tumor-to-normal tissue perfusion ratio, thereby enhancing the access of drug-MAb conjugates to tumors and increasing the effectiveness of tumor therapy with the use of drug-MAb conjugates.     

Enhancement of interferon antitumor action by sodium butyrate.

Sodium butyrate together with interferon enhances the antitumor effect of interferon in vivo. When Sarcoma 180 TG cells are inoculated in mice, the mean survival time and final survival rate are greatly increased compared to those for treatment with interferon alone. Similarly, a significant delay in the mean survival time is observed when mice inoculated with L1210 cells are treated with sodium butyrate and interferon. This effect could be due at least in part to a potentiation of interferon action on the tumor cells.     

In vitro and in vivo potentiation by lonidamine of the antitumor effect of adriamycin

Lonidamine (LND), a powerful antispermatogenic compound, has been shown to impair differentially the energy metabolism of normal and neoplastic cells and to increase significantly the survival of animal bearing experimental tumors. Clinical trials are presently ongoing and preliminary favourable results have been obtained with LND as a single agent or associated with other antineoplastic drugs. In this work the effect of the combination LND plus ADM was investigated on in vitro and in vivo tumors. The in vitro effect was analysed by the colony forming technique and the in vivo antitumor activity was assessed by means of local control parameters, increase in host lifespan and weight reduction of metastasing target organs (liver, kidney, ovary). The results obtained indicate that LND is poorly effective when used alone, while a very high cytotoxicity is observed when it is combined with ADM. Exposure of cells to different time-sequences and schedules of both drugs elicits a different response. In particular a synergistic effect is obtained when ADM precedes LND. These results have been preliminarily confirmed by in vivo studies.     

Susceptibilities of normal and malignant human lung cells in culture to the cytocidal action of antitumor agents.

Cultured normal and malignant human lung cells were examined for their different sensitivities to the cytocidal action of nine antitumor and three non-antitumor agents. The malignant cells were killed preferentially at lower concentrations and in a shorter time with each antitumor agent, Adriamycin, neocarzinostatin, bleomycin, actinomycin D, mitomycin C, carboquone, 1-beta-D-arabinofuranosylcytosine, 5-fluorouracil, and 5-fluorodeoxyuridine. Among these, Adriamycin, 5-fluorouracil, and 5-fluoro-deoxyuridine exhibited a higher differential lethal action on the malignant cells than did the other antitumor agents. The two cell lines exhibited little difference in cytolytic sensitivity to non-antitumor cytotoxic agents such as amphotericin B, G-strophanthin, and alph-amanitin.     

A novel class of antitumour agents. II. In vitro testing.

Suspensions of Walker and HeLa cells, rat fibroblasts and human stimulated lymphocytes were incubated over various periods with the synthetic amino steroid, 2 beta,16 beta-dipiperidino-5 alpha-androstane-3 alpha,17 beta-diol dipivalate (DAP). The acute cell destroying effect was found to be exponentially time and dose dependent within a certain range. With lower nontoxic doses, decreases in the mitotic and labelling indices were observed, and clotted mitotic figures occurred. The effects were essentially the same for all experimental cell types; chromosome alterations were not seen.     

Alteration of melanoma cell phenotype following in vitro culturing and exposure to cytostatic agents

Pleiotropic drug resistance is supposed to be associated with a particular tumor cell phenotype, defined by certain plasma membrane glycolipids. Therefore we wondered how far chemosensitivity in vitro correlates with phenotypic characteristics of melanoma cells, which are known to be highly refractory to cytocidal agents. 13 monolayer cell cultures of metastatic melanoma derived from 9 patients were tested with 12 monoclonal antibodies against constitutive, differentiation- and progression-associated antigens. In parallel these primary cell cultures were subjected to a proliferation inhibition assay in the presence of dacarbazine, cis-platinum and carboplatinum. Transferring melanoma cells from original tissue-suspensions into short-term monolayer cultures caused a change in the expression of certain tumor antigens in 54% of 104 assays. In addition, the incubation of the cultivated cells with various cytostatic agents caused them to alter their phenotype in 32% of 128 assays. Irrespective of the spontaneous or induced changes in the antigen patterns, cells lacking HLA-ABC and/or HLA-DR were inhibited more markedly by cytostatic agents as compared to those other cells expressing these antigens. The data suggest, that pretherapeutic determination of tumor cell phenotype may provide clinically useful information for therapeutic decisions in patients with metastatic melanoma.     

Dialysability of cytostatic drugs. Experimental studies in vitro

There are no established guidelines for detoxification for most cases of overdosage or intoxication with cytostatic drugs. Little is known about the dialysability of cytostatic drugs. To obtain further information on the dialysability of cytostatic drugs, human plasma was incubated with cytostatic drugs and dialysed in vitro using "mini-modules" with capillaries identical to clinical use. Cytotoxicity before and after dialysis was measured in a biological test system using permanent human lymphoblast cultures (LS2). The 20 cytostatic drugs studied could be categorised as follows: Good dialysability in vitro: methotrexate, 5-fluorouracil, cytarabine, actinomycin D, mitomycin C, 4-OH-cyclophosphamide, ifosfamide, melphalan, dacarbazine, cisplatin. Intermediate dialysability in vitro: adriamycin, epirubicin, carmustine. Ineffective dialysability in vitro: daunorubicin, vincristine, vinblastine, vindesine, etoposide, teniposide, mitoxantrone. These in vitro results cannot be transferred automatically into the in vivo situation because of specific drug distribution and metabolic rates. Considering pharmacokinetic data, the following recommendations can be made for practical clinical purposes: Detoxification by hemodialysis in vivo: Possibly effective: Methotrexate, 5-fluorouracil, mytomicin C, cyclophosphamide, ifosfamide, melphalan, carmustine, dacarbazine. Ineffective: Adriamycin, epirubicin, daunorubicin, mitoxantrone, actinomycin D, etoposide, teniposide, vincristine, vinblastine, vindesine, cytarabine, cisplatin.     

Inhibition of invasion activity in vitro by a novel class of antitumor agents: silatrane derivatives

The effect of several silatranes on in vitro invasion of the human amnion basement membrane (BM) by A549 human lung carcinoma cells was examined. Cells treated for two days with the derivatives were examined for invasive activity in the absence of the compounds. From silatrane dose-invasion response curves, an 80% inhibition of invasiveness compared to untreated cells was obtained with 40 micrograms/mg of 1-vinyl silatrane, 50 micrograms/ml of 1-(p-aminophenyl) silatrane, 80 micrograms/mg of 1-(3-phenylthiocarbamidopropyl) silatrane, 66 micrograms/ml of parent silatrane or 171 micrograms/ml of 1-bromosilatrane. Treatment with these doses had no effect on viability, growth or BM attachment of A549 cells.