Structural changes of serum albumin in response to oxidative stress caused by Walker-256 carcinosarcoma growth.

AIM: To assess oxidative stress and structural changes of the serum albumin in rats with transplanted Walker-256 carcinosarcoma (W256) strains with varying sensitivity to doxorubicin (Dox). MATERIALS AND METHODS: The study was performed on female Wistar rats with transplanted W256. On the 9th day after tumor cell transplantation an analysis of peripheral blood, oxidative stress parameters, and structural changes of serum albumin of experimental animals was performed. RESULTS: On the 9th day after W256 transplantation a significant increase in the leukocyte counts was observed in the groups of animals with the Dox-resistant and parental (Dox-sensitive) W256 tumors compared with the group of the intact animals: up to 14.24 ± 1.92 â€¢ 103/µl and 9.78 ± 1.03 â€¢ 103/µl, vs 8.92 ± 1.04 â€¢ 103/µl, respectively, due to the increase of granulocyte and monocyte counts. The number of lymphocytes was within the normal range. The level of hemoglobin and the erythrocyte counts were also within normal limits, but hematocrit in both groups of animals with tumors somewhat increased against the background of 1.2-fold elevation of the mean erythrocyte volume. In the group of rats with Dox-resistant W256, there was observed a decrease in the plateletcrit by almost 22% and thrombocyte counts - by 28%. Analysis of oxidative stress indices revealed a significant increase in the level of reactive oxygen species, 2-fold increase of malonic dialdehyde level and the degree of oxidative damage of blood plasma proteins, as well as a decrease in the activity of catalase in hemolysates (by 12-15%) in both groups of tumor-bearing rats. With the use of differential scanning calorimetry, UV and fluorescence spectroscopy we have revealed anomalous conformational changes of albumin caused by tumor development: structural rearrangements in the region of its first drug binding site located in the IIA domain, separation of globular parts of albumin molecule, and partial "opening" in a protein molecular three-domain structure resulting a loss of its thermal resistance. CONCLUSION: The development of transplanted Walker-256 carcinosarcoma, especially its Dox-resistant variant, results in severe metabolic intoxication reflected in alteration of hematological parameters, and indices of oxidative stress, as well as architectonic changes of serum albumin.

Hypoxia level and matrix metalloproteinases-2 and -9 activity in Lewis lung carcinoma: correlation with metastasis.

AIM: To investigate the relationship between tumor hypoxia in vivo, activity of matrix metalloproteinases (MMPs), and metastatic potential of tumor. MATERIALS AND METHODS: Lewis lung carcinoma (3LL) was used in this study. Total activity of MMP-2 and -9 in tumor was measured biochemically, tumor hypoxia level was assessed by (31)P NMR spectroscopy in tissue perchloric extracts. RESULTS: It was determined that hypoxia level in primary tumor has been concomitantly increasing along with tumor growth and correlated with metastasis level in lung. The positive correlation between hypoxia level and activities of MMP-2 and MMP-9 in primary tumor was registered. Moreover, the activity of MMP-2 and -9 in 3LL (primary tumor) directly correlates with metastasis level in lung. CONCLUSION: This study demonstrated that the growth of primary tumor is distinctly accompanied by an increase of tumor hypoxia level which positively correlates both with the activity of MMP-2 and -9 in primary tumor and metastatic efficiency.

Modifying effect of organocobalt complexes on the tumour response to anticancer treatments.

A new type of agents are proposed for combined cancer therapy. They are organocobalt (III) chelates containing a sigma-bounded organyl group and a mixed tridentate ligand derived from a Schiff base. These complexes generate free radicals due to the action of protons in physiological ranges of pH and temperature, and hence are conceivably capable of selectively attacking a malignant neoplasm that is slightly acidic and can be made even more so by introducing some means intensifying glycolysis. An in vivo examination was performed using transplanted rat tumours (Guerin and Walker 256 carcinomas, Sarcoma 45). The modifying effect of one of these complexes on the tumour response to cis-DDP, radiation and/or local hyperthermia was tested by means of tumour growth delay assay and local tumour control. The potentiating effect of the complex was maximal when it was administered 60-90 minutes prior to other agents (cisDDP, X-irradiation heat). The enhancement ratio was found to be ca. 2.0-4.0 for cisDDP and 2.0 for radiation. In conclusion, in our tumour models, an increase of the antitumour effect was obtained for conventional antitumour agents when they were supplemented with organocobalt complex. It can be hypothesised that DNA in tumour cells may be considered to be the main target for organocobalt complexes.