Influence of Polydatin on the Tumor Microenvironment In Vitro: Studies with a Colon Cancer Cell Model.

The tumor microenvironment of colon carcinoma, the site at which tumor cells and the host immune system interact, is influenced by signals from tumor cells, immunocompetent cells, and bacterial components, including LPS. A large amount of LPS is available in the colon, and this could promote inflammation and metastasis by enhancing tumor cell adhesion to the endothelium. Polydatin (PD), the 3-ß-D-glucoside of trans-resveratrol, is a polyphenol with anti-cancer, anti-inflammatory, and immunoregulatory effects. This study was designed to explore whether PD is able to produce antiproliferative effects on three colon cancer lines, to reduce the expression of adhesion molecules that are upregulated by LPS on endothelial cells, and to decrease the proinflammatory cytokines released in culture supernatants. Actually, we investigated the effects of PD on tumor growth in a coculture model with human mononuclear cells (MNCs) that mimics, at least in part, an in vitro tumor microenvironment. The results showed that PD alone or in combination with MNC exerts antiproliferative and proapoptotic effects on cancer cells, inhibits the production of the immunosuppressive cytokine IL-10 and of the proinflammatory cytokines upregulated by LPS, and reduces E-selectin and VCAM-1 on endothelial cells. These data provide preclinical support to the hypothesis that PD could be of potential benefit as a therapeutic adjuvant in colon cancer treatment and prevention.

Chemo-immunotherapy of colorectal carcinoma: preclinical rationale and clinical experience.

Advanced colorectal cancer is a common disease with an high mortality rate. For four decades, pharmacological treatment of the advanced disease was based on the use of 5-fluorouracil alone or in combination with biomodulators such as folinic acid and intereferon alpha. In the last 5 years, response to therapy has been considerably ameliorated thanks to the discovery of new drugs such as oxaliplatin and CPT-11. These agents, in combination with 5-fluorouracil, according to various schedules of treatment, have reached a significant improvement of palliation, response rate and survival. Immunotherapy is an uprising modality of treatment for human cancer including colorectal carcinoma. Its rationale is based on the knowledge that tumour cells are genetically unstable and produce molecular structures which allow their recognition and destruction by the immune-surveillance system. Therefore, humoral as well as cellular compartments of the immune system can be utilized according to a "passive" strategy (e.g. monoclonal antibody administration and adoptive immunotherapy) or an "active" approach, by using different modalities of vaccine therapy. In this context, monoclonal antibodies (mAbs) and cancer vaccines are being tested for the treatment of advanced colorectal cancer. Due to their genetic instability and extraordinary adaptative potential, tumour cells may acquire resistance to the immune effectors and mAbs exactly as they do for cytotoxic drugs. To improve the results of both immunological and chemical modality of cancer treatment, an increasing number of authors is starting to combine chemo and immunotherapy in the attempt to circumvent the limitations of both strategies. This report tries to review the possible rationale of the chemo-immunotherapy combination, illustrating preliminary results of preclinical and clinical studies.

Dendritic cell-mediated cross-presentation of antigens derived from colon carcinoma cells exposed to a highly cytotoxic multidrug regimen with gemcitabine, oxaliplatin, 5-fluorouracil, and leucovorin, elicits a powerful human antigen-specific CTL response with antitumor activity in vitro.

Gemcitabine, oxaliplatin, leucovorin, and 5-fluorouracil (GOLF) is a novel multidrug regimen inducing high levels of necrosis and apoptosis in colon carcinoma cells. This regimen is also able to promote a process of Ag remodeling including up-regulation of immunotherapy targets like carcinoembryonic Ag (CEA), thymidylate synthase (TS). We have conducted a preclinical study aimed to investigate whether these drug-induced modifications would also enhance colon cancer cell immunogenicity. Several CTL lines were thus generated by in vitro stimulating human HLA-A(*)02.01(+) PBMCs, from normal donors and colon cancer patients, with autologous dendritic cells cross-primed with cell lysates of colon cancer cells untreated, irradiated, or previously exposed to different drug treatments including the GOLF regimen. Class I HLA-restricted cytolytic activity of these CTL lines was tested against colon cancer cells and CEA and TS gene transfected target cells. These experiments revealed that CTLs sensitized with GOLF-treated cancer cells were much more effective than those sensitized with the untreated colon carcinoma cells or those exposed to the other treatments. CTL lines sensitized against the GOLF-treated colon cancer cells, also expressed a greater percentage of T-lymphocyte precursors able to recognize TS- and CEA-derived peptides. These results suggest that GOLF regimen is a powerful antitumor and immunomodulating regimen that can make the tumor cells a suitable means to induce an Ag-specific CTL response. These results suggest that a rationale combination of GOLF chemotherapy with cytokine-based immunotherapy could generate a chemotherapy-modulated Ag-specific T-lymphocyte response in cancer patients able to destroy the residual disease survived to the cytotoxic drugs.

Cytotoxic activity of Hypericum perforatum L. on K562 erythroleukemic cells: differential effects between methanolic extract and hypericin.

The influence of a methanolic extract of Hypericum perforatum L. and of purified hypericin has been comparatively tested on the growth of a human erythroleukemic cell line (K562). After 1 h exposure to increasing concentrations (as hypericin content) of both agents in the dark, leukemic cells were grown for 24 h and 48 h. The effects on cell growth were determined by viable cell count, flow cytometry analysis and fluorescence microscopy. Our data show that purified hypericin has only a weak inhibitory effect on cell growth and no effect in inducing apoptotic cell death. In contrast, the Hypericum flower extract shows a significant concentration-dependent and long-lasting inhibition of cell growth, and induces apoptotic cell death. This work con fi rms the interesting role of Hypericum perforatum L. in cancer therapy and strongly supports the hypothesis that agents, other than hypericin, present in the total extract can impair tumor cell growth acting separately or in a combined manner.

Combined treatment with temozolomide and poly(ADP-ribose) polymerase inhibitor enhances survival of mice bearing hematologic malignancy at the central nervous system site.

Temozolomide (TZM) is a DNA-methylating agent that has recently been introduced into various clinical trials for treatment of solid or hematologic neoplasias, including brain lymphomas. In the current study, we have investigated whether the antitumor activity of TZM could be selectively enhanced at the central nervous system (CNS) site by intracerebral injection of a poly(ADP-ribose) polymerase (PARP) inhibitor. Mice were injected intracranially with lymphoma cells. The PARP inhibitor NU1025 (1 mg/animal) was delivered intracerebrally, whereas TZM was given as a single or a fractionated dose of 200 mg/kg by intraperitoneal administration. Results indicated that this drug combination significantly enhanced the survival of tumor-bearing mice and that this fractionated modality of treatment was the most effective schedule. Increased survival time was related to a marked reduction of tumor growth, as evidenced by histologic studies. Treatment with TZM alone was ineffective. This is the first report exploring in vivo the combination of TZM with PARP inhibitor for intracerebral neoplasias.