The effects of taurolidine, a novel antineoplastic agent, on human malignant mesothelioma.

PURPOSE: Malignant mesothelioma (MM) is a cancer with uniformly poor responses to current therapeutic regimens. This study evaluates whether taurolidine, a novel antineoplastic agent, is effective against human MM cell lines and a murine model of human MM. EXPERIMENTAL DESIGN: Cell growth inhibition and viability assays were performed on REN, LRK, and H28 cell lines after 24-72-h exposure to 0-200 microm taurolidine. Cell cycle analysis with annexin-V binding, terminal deoxynucleotidyl transferase-mediated nick end labeling assay, electron microscopy, and response to the general caspase inhibitor z-VAD-fmk were performed on MM cell lines after 24-72-h exposure to 50-150 microm taurolidine. Athymic mice were given i.p. injections of 20 x 10(6) REN cells, followed by i.p. taurolidine (17.5 or 20 mg), 3 days/week for up to 3 weeks. Tumors were assessed at day 30. All statistical tests were two-sided. RESULTS: A 72-h exposure of MM cells to taurolidine showed IC50 of 28-42.7 microm and 50% viability at 49.8-135 microm. Annexin V assay for apoptosis revealed significant increases in annexin binding after 24-72-h exposure to 50-150 microm taurolidine (P <0.05), which was significantly inhibited by z-VAD (P <0.05). MM cells exposed to 50-150 microm taurolidine for 24-72 h showed terminal deoxynucleotidyl transferase-mediated nick end labeling staining consistent with apoptosis, as well as structural evidence of apoptosis via electron microscopy. In vivo, there were significant tumor reductions (62 to >99% reduction) for all dosage regimens compared with untreated controls (P <0.001). In addition, all control animals exhibited ascites and diaphragmatic tumors while treated animals did not. CONCLUSIONS: Taurolidine has significant antineoplastic activity against MM in vitro and in vivo, in part, due to tumor cell apoptosis. These findings warrant further study for potential clinical usefulness.

Use of growth factors in the elderly patient with cancer: a report from the Second International Society for Geriatric Oncology (SIOG) 2001 meeting.

Over 70% of the total incidence of cancer recorded in Europe in 1996 was in the elderly population (> or =60 years). Despite such high statistics, elderly cancer patients have often been denied the treatment that younger patients routinely receive. The response of elderly cancer patients to full-dose chemotherapy treatment in several neoplasms is similar to that of younger patients, demonstrating that age should not be a barrier to the administration of potentially curative or palliative chemotherapy. In order to provide optimal treatment to elderly cancer patients, management guidelines are recommended which take into account various factors, such as the physical well-being of the patient, the type of malignancy and any conditions that may hamper compliance with chemotherapy. The evidence-based guidelines of the National Comprehensive Cancer Network (NCCN) in the US recommend that the safest and most effective treatment of cancer in older individuals may be achieved by proper patient selection based on comprehensive geriatric assessment, dose adjustment of renally excreted drugs, prophylactic use of haematopoietic growth factors in patients treated with chemotherapy of dose-intensity comparable to cyclophosphamide/doxorubicin/vincristine/prednisone (CHOP) and maintenance of haemoglobin levels > or =12 g/l. The objective of this article is to report the conclusions of the meeting of the International Society of Geriatric Oncology (SIOG) in September 2001, including the need for geriatric assessment to tailor the management of patients to their personal circumstances and general health and the importance of evidence-based guidelines for the management of elderly cancer patients cannot be over-estimated.

A role for MAP kinase in the antitumor activity of a nucleoside analog.

Nucleoside analogs (NAs) have been used extensively in both antitumor and antiviral therapies. Their general mechanism of action has been postulated to result from incorporation into DNA, leading to disruption of DNA synthesis and DNA polymerase inhibition. To further explore the antitumor mechanisms of NAs we have evaluated ganciclovir (GCV), an NA antiviral agent, in herpes simplex virus thymidine kinase (HSV-TK) gene-modified tumor cells. This system allows specific evaluation of the antitumor effects of NAs because the antitumor effect is directly related to the phosphorylation of the prodrug GCV by the HSV-TK enzyme in the gene-modified tumor cells. We demonstrated that GCV incorporates into DNA and inhibits DNA polymerase, as has been observed in HSV-infected cells and with other antitumor NAs in tumor cells. A novel observation is that GCV activates MAP kinase within 1 hour of GCV exposure. This activation directly correlates with cytotoxicity, because inhibition of the MAP kinase extracellular regulated kinase (Erk) by PD98059, reversed GCV-mediated cytotoxicity. This effect appears to be specific to the Erk pathway, because inhibition of the p38 kinase with SB203580 had no effect on cytotoxicity. Further, GCV does not act as a DNA-damaging agent or activate general DNA-repair mechanisms, but does produce a number of metabolic disruptions, including a reversible decrease in NAD levels. These effects appear to be downstream of the earlier activation of Erk in this system, which may be a novel mechanism of action for GCV cytotoxicity in HSV-TK gene-modified tumor cells, and thus, needs to be further evaluated as the mechanism of tumor cell killing by other antitumor NAs.

Thrombospondin-1 plus irinotecan: a novel antiangiogenic-chemotherapeutic combination that inhibits the growth of advanced human colon tumor xenografts in mice.

Chemotherapy for the treatment of advanced or metastatic colon cancer, utilizing agents such as 5-fluorouracil (5-FU) and irinotecan (CPT-11), produce a 5-year survival of about 10%. Thus, the identification of new, effective, therapeutic regimens to treat this disease remains critically important. To this end, selected antiangiogenic agents, compounds that inhibit neovascularization, have been shown to produce a modest tumor growth-inhibitory effect with little systemic toxicity. Thus these agents are attractive candidates for use with conventional chemotherapeutic agents to treat this disease. To evaluate this approach, experiments were undertaken to assess the cytotoxic and antineoplastic activity of CPT-11 and the antiangiogenic agent thrombospondin-1 (TSP-1) in the HT-29 model of human colon cancer. These agents were chosen since CPT-11 is a camptothecin analogue efficacious in the treatment of colon cancer and TSP-1 is a human glycoprotein that possess antiangiogenic activity. As expected, in vitro studies revealed that a 5-day exposure to TSP-1 at concentrations up to 130 microg/ml was not cytotoxic alone and did not affect the cytotoxicity of CPT-11, or of its active metabolite SN38, in HT-29 cells. Similarly, in human umbilical vein endothelial cells, TSP-1 alone induced only a slight cell growth-inhibitory effect and did not significantly increase the cytotoxicity of either CPT-11 or SN38. The antineoplastic activities of TSP-1 and CPT-11 were assessed in athymic (nude) female mice bearing advanced subcutaneous xenografts of HT-29 cells. Mice received TSP-1 alone (5-40 mg/kg per day) intraperitoneally (i.p.), CPT-11 alone (100-300 mg/kg, i.p.), TSP-1 (10 mg/kg per day) plus CPT-11 (125 mg/kg), or TSP-1 (20 mg/kg per day) plus CPT-11 (150 mg/kg). TSP-1 was injected daily (Monday through Friday) for 4 weeks (20 injections in total) whereas CPT-11 was administered once weekly on days 0, 7, 14 and 21. By day 28, treatment with TSP-1 alone (5, 10 or 20 mg/kg per day) induced a dose-dependent inhibition of xenograft growth. Further, treatment with 10 or 20 mg/kg per day resulted in an average treated tumor size/control tumor size (T/C) on day 28 of 0.68 (range 0.64-0.71) or 0.58 (range 0.54-0.60), respectively. CPT-11 at all doses significantly inhibited tumor growth with an average T/C value of 0.21 (range 0.15-0.27). However, the 250 and 300 mg/kg regimens induced significant toxicity and mortality. When TSP-1 was combined with CPT-11, a significant ( P< or = 0.05) inhibition of tumor growth also was observed (T/C < or = 0.17, range 0.11-0.20). Importantly, this enhanced tumor growth inhibition was obtained without significant toxicity. The therapeutic implications of these findings are discussed.

Mechanistic and antineoplastic evaluation of taurolidine in the DU145 model of human prostate cancer.

Taurolidine (TRD) was designed in the 1970s as a broad-spectrum antibiotic and is used clinically at high doses without systemic toxicity. We have found that this agent possesses cytotoxic activity in human tumor cell lines and antineoplastic activity in mice bearing i.p. human tumor xenografts. We now report the mechanism by which TRD induces cell death in DU145 human prostate tumor cells. The IC50 (3 days) of TRD in this model was 16.8+/-1.1 microM. Cytotoxicity was associated with DNA debris and increased membrane phosphatidylserine externalization, both suggesting the induction of apoptosis. This was confirmed by the ability of TRD to induce PARP cleavage in these cells, an effect prevented by coexposure to the pan-caspase inhibitor zVAD-FMK. TRD exposure also resulted in the appearance of cytochrome c in the cytoplasm, procaspase 9 activation within 2 h of drug exposure and procaspase 8 activation 4 h after exposure. Parallel experiments revealed that cytochrome c appearance in the cytoplasm was not blocked by preexposure to zVAD-FMK, while activation of both procaspase 9 and procaspase 8 was prevented. Finally, antineoplastic activity was assessed in mice bearing subcutaneous xenografts of DU145 cells. Initial studies quantitated the toxicity of three i.p. injections of TRD, administered as one injection on three alternate days per week, at doses ranging from 500 to 700 mg/kg per injection. The 500 mg/kg dose produced about 7% mortality after three cycles and effectively inhibited tumor growth. Thus, TRD induced mitochondrial-mediated apoptosis in DU145 human prostate tumor cells and this effect could be exploited for therapeutic advantage.

The antibacterial drug taurolidine induces apoptosis by a mitochondrial cytochrome c-dependent mechanism.

The antibacterial agent taurolidine (TRD) has been used as a lavage antibiotic to prevent development of peritonitis in patients after surgery. We recently showed that TRD induced growth arrest and apoptosis of a variety of cultured cell lines derived from human solid tumors and also significantly inhibited the growth of human ovarian tumors in a mouse model. In this report, we present data to show that TRD, at concentrations below the doses that are used to treat patients in the clinic, induces apoptosis of human leukemia HL-60 cells by a mitochondrial cytochrome c-dependent pathway.

Role of p21 in apoptosis and senescence of human colon cancer cells treated with camptothecin.

Treatment of cells with the anti-cancer drug camptothecin (CPT) induces topoisomerase I (Top1)-mediated DNA damage, which in turn affects cell proliferation and survival. In this report, we demonstrate that treatment of the wild-type HCT116 (wt HCT116) human colon cancer cell line and the isogenic p53(-/-) HCT116 and p21(-/-) HCT116 cell lines with a high concentration (250 nm) of CPT resulted in apoptosis, indicating that apoptosis occurred by a p53- and p21-independent mechanism. In contrast, treatment with a low concentration (20 nm) of CPT induced cell cycle arrest and senescence of the wt HCT116 cells, but apoptosis of the p53(-/-) HCT116 and p21(-/-) HCT116 cells. Further investigations indicated that p53-dependent expression of p21 blocked apoptosis of wt HCT116 cells treated with 20 nm, but not 250 nm CPT. Interestingly, blocking of the apoptotic pathway, by Z-VAD-FMK, in p21(-/-) HCT116 cells following treatment with 20 nm CPT did not permit the cells to develop properties of senescence. These observations demonstrated that p21 was required for senescence development of HCT116 cells following treatment with low concentrations of CPT.