Maria Marczak

Lovastatin and tumor necrosis factor‐α exhibit potentiated antitumor effects against Ha‐ras‐transformed murine tumor Via inhibition of tumor‐induced angiogenesis

Lovastatin, a drug commonly used in the treatment of hypercholesterolemia, has previously been reported to exert potentiated antitumor activity when combined with either tumor necrosis factor‐α (TNF‐α), cisplatin or doxorubicin in a melanoma model in mice. Since lovastatin interferes with the function of ras oncogene‐encoded (Ras) proteins, we have investigated the antitumor activity of lovastatin and TNF‐α using a Ha‐ras‐transformed murine tumor model. In in vitro studies, lovastatin inhibited the growth of cells transformed with Ha‐ras oncogene (Ras‐3T3 and HBL100‐ras cells) more effectively than control NIH‐3T3 and HBL100‐neo cells. In in vivo experiments, the Ras‐3T3 tumor demonstrated significantly increased sensitivity to combined treatment with both lovastatin (50 mg/kg) and TNF‐α (1 μg/day) compared with either agent alone. Combined treatment with both agents also resulted in greater inhibition of blood‐vessel formation. Ras‐3T3 tumor cells produced increased amounts of vascular endothelial growth factor (VEGF) and lovastatin effectively suppressed VEGF production by these cells. Our results suggest that lovastatin increases antitumor activity of TNF‐α against tumor cells transformed with v‐Ha‐ras oncogene via inhibition of tumor‐induced blood‐vessel formation. Int. J. Cancer 81:560–567, 1999.

Inhibition of tumor cell-induced angiogenesis by retinoids, 1,25-dihydroxyvitamin D3 and their combination

Tumor-induced angiogenesis (TIA), i.e., the ability of transformed cells to stimulate new blood vessel formation is an important factor contributing to tumor growth and invasiveness. The antiangiogenic effect of the retinoids, all-trans retinoic acid, 13-cis retinoic and 9-cis retinoic acid, of 1,25-dihydroxyvitamin D3, and of their combinations were studied using an experimental system in vivo. TIA was induced in immunosuppressed mice by intradermal injection of the two human transformed keratinocyte lines, Skv-e2, harboring DNA of human papillomavirus (HPV) type 16, and HeLa, harboring HPV18 DNA. The three retinoids and 1,25-dihydroxyvitamin D3, when administered systemically to mice, before the angiogenesis assay significantly decreased TIA. Their combination led to a synergistic inhibition of TIA. These results provide the basis for the use of combination of retinoids and 1,25-dihydroxyvitamin D3 in treatment of neoplastic diseases.

Retinoids, Interferon α, 1,25-dihydroxyvitamin D3 and their combination inhibit angiogenesis induced by non-HPV-harboring tumor cell lines. RARα mediates the antiangiogenic effect of retinoids

Abstract Retinoids combined with interferon alpha-2a (IFN alpha) or 1,25-dihydroxyvitamin D3 [1,25(OH)2D3] have shown marked synergistic inhibitory effects on angiogenesis induced by tumor cell lines harboring DNA of oncogenic human papillomaviruses (HPV) type 16 or 18. This report demonstrates comparable effects of these compounds on angiogenesis induced by non-HPV-bearing transformed cell lines, including breast carcinoma (T47D) and vulval carcinoma (A431) cell lines. Systemic treatment of mice with all-trans retinoic acid, 13-cis retinoic acid, 9-cis retinoic acid, IFN alpha or 1,25(OH)2D3 significantly decreased tumor cell-induced angiogenesis (TIA). In vitro pretreatment of T47D and A431 cells with these compounds also led to inhibition of their angiogenic capability when tested in the TIA assay. The inhibitory effects of retinoids could be counteracted by a selective antagonist of the nuclear retinoic acid receptor RAR alpha, suggesting a RAR alpha mediated mechanism of angiogenesis inhibition. The antiangiogenic effect of retinoids could be significantly enhanced by combination with IFN alpha or 1,25(OH)2D3. The results provide a further basis for the use of combinations of retinoids with IFN alpha or 1,25(OH)2D3 in the treatment of angiogenesis-dependent malignancies.

Imiquimod is a strong inhibitor of tumor cell-induced angiogenesis.

Background  Imiquimod, a potent immunomodulator, not having a direct antiproliferative activity, was found to be effective in genital and cutaneous premalignancies and malignancies. As tumor development depends on blood vessel supply, the inhibition of angiogenesis could be responsible for the antitumor activity.

Interleukin 12 and indomethacin exert a synergistic, angiogenesis-dependent antitumor activity in mice

Nonsteroidal anti-inflammatory drugs have been shown to reduce the incidence and mortality from colorectal cancer. It has recently been demonstrated that these drugs are capable of suppressing the production of pro-angiogenic factors from tumor cells. The mechanisms of antitumor action of interleukin 12 include the enforced secretion of anti-angiogenic factors and stimulation of antitumor immunity. Therefore, we hypothesized that the combination of a model nonsteroidal anti-inflammatory drug--indomethacin and interleukin 12--would result in enhanced angiogenesis-dependent antitumor effects against a colon-26 carcinoma cells transplanted into syngeneic mice. As expected the combined administration of both agents simultaneously resulted in a strengthened antitumor activity that was manifested as a retardation of tumor growth and prolongation of mouse survival. Importantly some mice were completely cured after the combined treatment. As administration of interleukin 12 and indomethacin resulted in enhanced inhibition of angiogenesis it seems possible that prevention of new blood vessel formation is one of the mechanisms responsible for the observed antitumor effects.

Antitumor activity of tributyrin in murine melanoma model

Butyric acid has been known to inhibit growth and to induce differentiation of a variety of tumor cells. Butyrate-treated tumor cells have also been observed to undergo apoptosis. Although butyrate compounds have demonstrated antitumor activity in murine tumor models and have already been admitted to clinical trials in tumor patients, the exact mechanism of their antitumor effects has not been elucidated. The results of our study showed antitumor activity of tributyrin, a butyric acid prodrug, in murine melanoma model and are strongly suggestive that antiangiogenic effects could participate in antitumor effects of butyrate compounds in vivo.

Augmented antitumour effects of combination therapy with TNP-470 and chemoimmunotherapy in mice

Abstract Purpose. To investigate antitumour efficacy of the combination of the antiangiogenic agent TNP-470 combined with chemoimmunotherapy in different tumour models in mice Materials. B6D2F1 mice and BALB/c mice were inoculated in the footpad of the right hind limb with B16F10 melanoma cells or colon adenocarcinoma cells C-26, respectively. Subsequently, they received therapy consisting of TNP-470 and/or IL-12 and tumour growth was observed. In the melanoma model this therapy regimen was combined with cisplatin in a subtherapeutic dose. The antiangiogenic action of the tested agents was evaluated using tumour-induced angiogenesis assay in vivo. In order to analyse interactions between TNP-470 (or cisplatin) and IFN-γ on tumour cells in vitro, the following methods were used: MTT assay, Western blot analysis, and flow cytometry analysis. Results. Administration of the combined therapy with TNP-470 and IL-12 resulted in augmented antitumour activity in colon-26 and B16F10 melanoma models. Addition of cisplatin further enhanced efficacy of this combined therapy in the melanoma model. We showed that antitumour activity of this combined therapy is mediated by multiple mechanisms: not only is enhancement of the antiangiogenic activity mediated by TNP-470 and IL-12 but also by the synergistic cytostatic/cytotoxic action of IL-12-induced IFN-γ and TNP-470 or cisplatin on tumour cells. The experiments revealed that TNP-470 together with IFN-γ leads to the increased expression of p21 protein in cancer cells, which in turn may contribute to their cytostatic/cytotoxic action in vitro. Conclusion. Our experiments show a successful TNP-470-based combination therapy and suggest that the enhancement of the antitumour activity could be explained by a concomitant effect on both endothelial and tumour cell compartments.

Retinoids and Ifnα Synergistically Decrease Tumor Cell-Induced Angiogenesis and Stimulate Lymphocyte Induced Angiogenesis

The growth of solid tumors requires a vascular supply, formed in the process of tumor-induced angiogenesis (TIA) (Folkman, 1990). TIA is an active sprouting of capillaries and new blood vessel formation due to some tumor cell-derived angiogenic factors capable of stimulating endothelial. cell proliferation and migration (Folkman and Klagsburn, 1987). TIA was shown to precede or accompany malignancy not only in various experimental. systems (Bouck, 1990) but also in natural. human tumors of the cervix, skin, breast and bladder (Folkman, 1990). The presence of newly formed blood vessels on the surface of the cervix can indicate an underlying but invisible tumor (Sillman, et al., 1981). Quantitation, either by routine histology or immunohistochemistry, of the number of blood vessels on tissue sections of breast carcinoma was shown to be useful for estimation of relapse-free survival. rate (Weidner et al., 1992) and probability of the metastatic disease (Horak et al., 1992).