Histopathological evaluation of tumor necrosis and volume after cyanogenic chemotherapy

PURPOSE: To determine the percentage of tumoral necrosis and volume after cyanogenic chemotherapy. METHODS: Histopathological findings of 20 Swiss mice inoculated subcutaneously in the left abdominal wall with 0.05 ml of cell suspension containing 2.5 x 105 viable cells of the Ehrlich tumor were evaluated. The tumor response to cyanogenic chemotherapy was determined using a system that comprises two inhibition factors of tumor growth by calculating the percentage of necrosis in the tumor tissue and calculation of tumor volume in treated animals relative to that in control animals. The importance of this system has been validated by the correlation between tumor inhibition in the groups treated with the respective percentages of necrosis. RESULTS: While the control group presented an average of 13.48 ± 14.71% necrosis and average tumor volume of 16.18 ± 10.94, the treated group had an average of 42.02 ± 11.58 and 6.8 ± 3.57, respectively. The tumor inhibition was significantly associated with treatment (p=0.0189). The analysis of necrosis percentage showed a significant prognostic importance (p=0.0001). CONCLUSION: It is concluded that the effect of cyanogenic chemotherapy showed strong inhibitory action of tumor growth, as well as an increase in its area of necrosis. .

Tackling radioresistance of hypoxic cells by metabolic modulation of bioenergetics--a 31P MRS study on perfused Ehrlich ascites tumor cells.

In an attempt to overcome resistance of hypoxic cells to radiotherapy, the combination of a hematoporphyrin derivative (Hpd) and 2-deoxy-D-glucose (2-DG), a promising radiomodifier, was evaluated by assessing the alterations in phosphorylated metabolites and bioenergetics induced in perfused Ehrlich ascites tumor (EAT) cells, using Phosphorus-31 Magnetic Resonance Spectroscopy (31P-MRS). By reducing flow rate of perfusion, a relatively hypoxic condition of tumor was simulated. Changes in bioenergetics levels induced by the combined treatment of Photosan, a Hpd, and 2-DG, under reduced perfusion conditions were more pronounced. Significantly higher uptake of 2-DG and irreversibility of the reduction in cellular bioenergetics induced by the combined treatment, observed under simulated hypoxic conditions, might have considerable implications in optimizing tumor radiotherapy using 2-DG as an adjuvant. These result also suggest the usefulness of this technique to easily simulate hypoxic conditions of tumors in vitro that could be used for rapid in vitro pharmacological evaluation of promising therapeutic strategies.

In vivo NMR spectroscopic studies on the bioenergetic changes induced by metabolic modulators in Ehrlich ascites tumour cells.

Changes in the energy metabolism of Ehrlich ascites tumour (EAT) cells induced by treatment with 2-deoxy-D-glucose (2-DG) alone and in combination with other metabolic modulators, were studied using in vivo nuclear magnetic resonance (NMR) spectroscopy. Accumulation of 2-DG-6-phosphate (2-DG-6-P) and cellular energy status as reflected in the ratio of beta ATP to inorganic phosphate (beta-ATP/Pi) in cells could be monitored as a function of time using P-31 NMR spectroscopy. Presence of 2-DG induced a significant decrease in the levels of nucleotide triphosphates, which continued to reduce for some time even after removing 2-DG from the vicinity of cells. When administered along with 3-O-methyl-D-glucose (3-O-MG), 2-DG phosphorylated at a slower rate and the resultant 2-DG-6-P accumulated to a lesser extent than that obtained with 2-DG alone. Treatment with Photosan II, a haematoporphyrin derivative (Hpd), has been reported to increase the glucose utilisation and rate of glycolysis. Upon concomitant administration of 2-DG along with Hpd (after Hpd pretreatment for 1-2 hr), the extent of phosphorylation of 2-DG increased. The combination of 2-DG with 3-O-MG or Hpd reduced the energy status (beta-ATP/Pi) to a greater extent and the recovery was considerably less upon removal of the treatment, compared to the effects of either drug administered separately. Since metabolic depletion of ATP is known to inhibit the post-irradiation DNA repair processes, it is hypothesized that the use of these drug combinations, as adjuvants to tumour radiotherapy, should enhance the therapeutic efficacy and selectivity.