Mouse skin tumor promotion by sodium arsenate is associated with enhanced PCNA expression.

Drinking water contamination by arsenicals remains a major public health problem in many parts of the world more particularly in India and Bangladesh. Despite arsenic being a health hazard and implicated in human carcinogenesis, the experimental evidence available is much limited even now and the mechanisms involved during carcinogenesis and tumor promotions are not clear. Accordingly, in this study, we have studied the tumor promoter effects of sodium arsenate on mouse skin tumor promoter model system using 9,10-dimethyl-1,2-benzanthracene (DMBA) as a initiating carcinogen. Our studies showed development of papillomas on mice skin treated with only DMBA. However, mice treated with DMBA on skin and administered arsenate (As) in drinking water showed development of well differentiated squamous cell carcinomas. Further, both by immunohistochemistry and western blotting analysis studies higher levels of proliferating cell nuclear antigen (PCNA) was observed in mice treated with DMBA plus arsenate compared to only DMBA treated group. PCNA is known to be associated with S phase and DNA replication of the cell cycle. The plain controls and arsenate controls did not show significant difference either in tumor development or in PCNA levels. The present study demonstrates mouse skin tumor promoting effect of arsenate which seems to be associated with abnormal cell proliferation as indicated by higher levels of PCNA expression.

Bioevaluation of radioactive bandages in a murine model of melanoma.

PURPOSE: To study the effectiveness of a radioactive bandage incorporating a beta(-) emitter for the treatment of superficial tumours like melanoma. MATERIALS AND METHODS: (188)Re tin particles were immobilized on a bandage patch ((188)Re bandage). The effectiveness of the (188)Re bandage for controlling tumour growth was tested in C57BL/6 mice bearing BL6/FIO melanoma. The effect of the single dose delivered, two-dose treatment and time of contact of bandages on the skin was studied by following tumour size. RESULTS: Tumour growth was delayed significantly in treated animals compared with controls. Complete tumour regression was observed with some doses of radiation. Histology studies and dose-rate calculations were also carried out to evaluate the effectiveness of (188)Re bandages. CONCLUSIONS: Radioactive bandages could be a promising modality for the treatment of skin cancers.

Tumor regression of B16F10 melanoma in vivo by prevention of neovascularization: study on theophylline.

The aim of this study was to determine the effect of theophylline on neovascularization and tumor regression in murine B16F10 melanoma. Theophylline had no direct toxicity to host and significantly reduced (p < 0.001) tumor volume and neovascularization in B16F10 melanoma implanted murine model. The effect of theophylline on neovascularization was observed distinctly in histologic analysis. This effect is mediated, in part by blocking endothelial cell proliferation, thereby preventing neovascularization of the tumor. Further investigations with theophylline can elucidate the exact mechanism of action which characterize neovascularization activity.

Induction of lymphomas on implantation of human oral squamous cell carcinomas in nude mice.

Cancer cells from five oral cancer patients and pleomorphic adenoma cells from one individual were inoculated as single cell suspension into subcutis of 30 Swiss nude mice and tail vein of additional 30 mice. Further, tumor tissue pieces from three oral cancer patients were xenografted s.c. in 18 nude mice, and 10 mice were kept as controls. In animals implanted with tumor pieces, 7/18 (39%) mice, developed squamous cell carcinoma at the site of inoculation within 8-15 days, while tumors were not observed in mice inoculated with single cell suspension, up to 60/90 days. In 8/68 (12%) mice, white foci were observed in several tissues, with hepatomegaly and splenomegaly noted in 27/68 (39%) mice. Histopathological examination of various tissues revealed presence of large cell lymphoma in several organs in 14/68 (21%) mice. No regional or distant metastasis of the implanted oral tumor cells was detected. Mice injected with cells from pleomorphic adenoma, also demonstrated large cell lymphoma in 2/10 (20%) mice, whereas none of the 10 control animals showed any gross abnormalities or microscopic abnormalities in several organs. 2/16 (12%) lymphomas exhibited positive reaction with mouse B cell antibodies illustrating the murine origin of the lymphomas, and these were immunophenotyed as B cell lymphomas. The lymphomas were also examined with mouse T cell antibodies and none reacted positively with the mouse T cell antibodies. The lymphomas also failed to react with human T cell, B cell and human Leucocyte common antigen (LCA) antibodies, indicating that the induced lymphomas were not of human origin. The tumor specimens from seven of eight oral cancer patients and the pleomorphic adenoma patient induced lymphomas in nude mice. Thus it appears that xenografting oral tumor cells into nude mice may cause induction of the murine lymphomas, and this needs further investigation.

Antimetastatic efficacy of niosomal pentoxifylline and its combination with activated macrophages in murine B16F10 melanoma model.

The aims of the present study were a) to enhance the effectiveness of antimetastatic agent, Pentoxifylline (PTX) by encapsulation in niosomes and b) to investigate the anticancer activity by combination therapy involving activated macrophages and PTX solution/PTX niosomes. Niosomes were prepared by lipid film hydration method. Particle size distribution revealed bimodal distribution with median vesicle size of 462 nm. The entrapment efficacy of PTX niosomes was found to be 9.64%. A cumulative release of 82.43% from niosomal suspension was observed at the end of 21 hours. Intravenous administration of niosomal PTX (6 mg/kg and 10 mg/kg) resulted in significant reduction in lung nodules in an experimental metastatic B16F10 model suggesting accumulation of PTX in a distant target organ-lung. Light microscopic observations of histologic sections showed a decrease in number of tumor islands in the lung. Macrophages activated by intraperitoneal injection of Iscove's Modified Dulbecco's Medium (IMDM) containing 20% fetal calf serum (FCS) followed by in vitro incubation with muramyl dipeptide (MDP) were more effective in controlling tumor spread than those activated by FCS alone. Combination therapy of activated macrophages and PTX solution/niosomal PTX showed no additive or synergistic effect in controlling tumor spread. Carbon clearance studies revealed that PTX inhibits the phagocytic ability of activated macrophages, thereby resulting in the failure of combination therapy.

Subchronic oral hepatotoxicity of turmeric in mice--histopathological and ultrastructural studies.

Dietary administration of the whole spice turmeric (0.2%, 1.0%, 5.0%) or ethanolic turmeric extract (ETE, 0.05%, 0.25%) for 14 days, at doses reported to be cancer preventive in model systems, were found to be hepatotoxic in mice. Histopathological evaluation showed coagulative necrosis accompanied by a zone of regenerating parenchymal cells of liver. The ultrastructural changes in liver parenchymal cells were non-specific reaction to injury. Results suggest mouse to be a susceptible species for turmeric induced toxicity.

Subchronic oral toxicity of turmeric and ethanolic turmeric extract in female mice and rats.

Subchronic oral toxicity of turmeric and ethanolic turmeric extract was studied in female Swiss mice and Wistar rats fed turmeric (0, 1 and 5%) and ethanolic turmeric extract (0, 0.05 and 0.25%) through diet for 14 and/or 90 days. The administration of a high dose of turmeric (5%) for longer duration (90 days) showed a significant reduction in body weight gain, alterations in absolute and/or relative liver weights, and hepatotoxicity i.e. focal necrosis or focal necrosis with regeneration both in mice and rats. In mice lower doses of turmeric i.e 0.2 or 1% for 14 days also showed hepatotoxicity and they were found to be more vulnerable to turmeric-induced hepatotoxicity than rats.

Chemopreventive efficacy of curcumin-free aqueous turmeric extract in 7,12-dimethylbenz[a]anthracene-induced rat mammary tumorigenesis.

The modulating effects of turmeric (T), ethanolic turmeric extract (ETE) and curcumin-free aqueous turmeric extract (CFATE) on the initiation or post-initiation phases of DMBA-induced mammary tumorigenesis were investigated in female Sprague-Dawley rats. Dietary administration of 1% T/0.05% ETE 2 weeks before, on the day of DMBA treatment (day 55) and 2 weeks after the single dose (15 mg/animal) of DMBA (during the initiation period) resulted in significant suppression of DMBA-induced mammary tumorigenesis as seen by a reduction in tumor multiplicity, tumor burden and tumor incidence. However, simultaneous administration of 1% T-derived CFATE as the sole source of drinking water during the initiation phase did not suppress DMBA-induced mammary tumorigenesis. Dietary administration of 1% T/0.05% ETE or 1% T-derived CFATE as the sole source of drinking water starting 48 h after DMBA treatment and continuing until the end of the experiment (during the post-initiation period) resulted in significant suppression of DMBA-induced mammary tumorigenesis as seen by reduction in the tumor multiplicity and/or tumor burden although tumor incidence was unaffected. The present data clearly indicate that dietary administration of T/ETE showed strong chemopreventive activity during initiation as well as post-initiation phases of DMBA-induced rat mammary tumorigenesis while CFATE was found to be weakly active only when it was administered during the post-initiation phase.

Inhibitory effects of curcumin-free aqueous turmeric extract on benzo[a]pyrene-induced forestomach papillomas in mice.

The modulating effects of curcumin-free aqueous turmeric extract (CFATE), ethanolic turmeric extract (ETE) and turmeric (T) powder on the benzo(a)pyrene (B(a)P)-induced forestomach tumors were investigated in Swiss female albino mice receiving oral administration of B(a)P at a dose of 1 mg twice weekly for 4 weeks. Administration of 0.2%/1.0%/5.0% turmeric-derived CFATE as sole source of drinking water or 0.01%/0.05%/0.25% ETE in diet or 0.2%/1.0%/5.0% T in diet, 2 weeks before, during and 2 weeks after the last dose of B(a)P (during initiation period) resulted in significant suppression of B(a)P-induced tumorigenesis when compared with the group receiving B(a)P and control diet/drinking water. Among different fractions tested, CFATE appears to be more powerful as not only did it reduce the tumor multiplicity to the lowest levels but it also significantly reduced the tumor incidence. Administration of 5.0% turmeric-derived CFATE as the sole source of drinking water or 0.25% ETE/5.0% T in diet starting from 48 h after the last dose of B(a)P (during the post-initiation period) until the termination of the experiment, also inhibited the formation of multiple gastric tumors by B(a)P, although the suppression of tumor multiplicity was appreciably more in the groups that received 5.0% turmeric-derived CFATE/0.25% ETE treatment during initiation with carcinogen, i.e. 2 weeks before, during and 2 weeks after the last dose of B(a)P. The present data clearly indicate the potential of turmeric-derived CFATE as a powerful chemopreventive fraction and also demonstrate the efficacy of lower, i.e. 1/25th and/or 1/5th of the reported, chemopreventive doses of T/ETE (essentially curcumins) in inhibiting B(a)P-induced forestomach tumors in mice.

Inhibition of lung homing of B16F10 by pentoxifylline, a microfilament depolymerizing agent.

B16 melanoma has proved to be an ideal model for investigating metastasis. The parental B16F1 line grows as a localized subcutaneous tumor in C57BL/6 or DBA/2 mice. However, by means of successive intravenous transplantation, a subline B16F10 has been established. This shows preponderant lung homing when transplanted by intravenous route into C57BL/6 mice. In this paper we have shown that pentoxifylline (PTX; Hoechst), a microfilament depolymerising agent can inhibit significantly this lung homing of B16F10 cells. It also had a marginal inhibitory effect on subcutaneous tumor growth.