Related expression of TRKA and P75 receptors and the changing copy number of MYC-oncogenes determine the sensitivity of brain tumor cells to the treatment of the nerve growth factor in combination with cisplatin and temozolomide.

Objectives Oncological diseases are an urgent medical and social problem. The chemotherapy induces not only the death of the tumor cells but also contributes to the development of their multidrug resistance and death of the healthy cells and tissues. In this regard, the search for the new pharmacological substances with anticancer activity against drug-resistant tumors is of utmost importance. In the present study we primarily investigated the correlation between the expression of TrkA and p75 receptors with the nerve growth factor (NGF) and cisplatin or temozolomide sensitivity of anaplastic astrocytoma (AA), glioblastoma (GB) and medulloblastoma (MB) cell cultures. We then evaluated the changing of copy numbers of MYCC and MYCN and its correlation with cytotoxicity index (CI) in MB cells under NGF exposition. Methods The primary cell cultures were obtained from the tumor biopsy samples of the patients with AA (n=5), GB (n=7) or MB (n=25) prior to radiotherapy and chemotherapy. The cytotoxicity effect of NGF and its combinations with cisplatin or temozolomide, the relative expression of TrkA and p75 receptors, its correlations with CI in AA, GB and MB primary cell cultures were studied by trypan blue cytotoxicity assay and immunofluorescence staining respectively. The effect of NGF on MYCC and MYCN copy numbers in MB cell cultures was studied by fluorescence in situ hybridization. Results We found that the expression of TrkA and p75 receptors (p=0.03) and its ratio (p=0.0004) depends on the sensitivity of AA and GB cells to treatment with NGF and its combinations with cisplatin or temozolomide. NGF reduces (p<0.05) the quantity of MB cells with six or eight copies of MYCN and three or eight copies of MYCC. Besides, NGF increases (p<0.05) the quantity of MB cells containing two copies of both oncogenes. The negative correlation (r=-0.65, p<0.0001) is established between MYCC average copy numbers and CI of NGF in MB cells. Conclusions The relative expression of NGF receptors (TrkA/p75) and its correlation with CI of NGF and its combinations in AA and GB cells point to the mechanism involving a cell death signaling pathway. NGF downregulates (p<0.05) some increased copy numbers of MYCC and MYCN in the human MB cell cultures, and upregulates normal two copies of both oncogenes (p<0.05).

Related expression of TRKA and P75 receptors and the changing copy number of MYC-oncogenes determine the sensitivity of brain tumor cells to the treatment of the nerve growth factor in combination with cisplatin and temozolomide.

OBJECTIVES: Oncological diseases are an urgent medical and social problem. The chemotherapy induces not only the death of the tumor cells but also contributes to the development of their multidrug resistance and death of the healthy cells and tissues. In this regard, the search for the new pharmacological substances with anticancer activity against drug-resistant tumors is of utmost importance. In the present study we primarily investigated the correlation between the expression of TrkA and p75 receptors with the nerve growth factor (NGF) and cisplatin or temozolomide sensitivity of anaplastic astrocytoma (AA), glioblastoma (GB) and medulloblastoma (MB) cell cultures. We then evaluated the changing of copy numbers of MYCC and MYCN and its correlation with cytotoxicity index (CI) in MB cells under NGF exposition. METHODS: The primary cell cultures were obtained from the tumor biopsy samples of the patients with AA (n=5), GB (n=7) or MB (n=25) prior to radiotherapy and chemotherapy. The cytotoxicity effect of NGF and its combinations with cisplatin or temozolomide, the relative expression of TrkA and p75 receptors, its correlations with CI in AA, GB and MB primary cell cultures were studied by trypan blue cytotoxicity assay and immunofluorescence staining respectively. The effect of NGF on MYCC and MYCN copy numbers in MB cell cultures was studied by fluorescence in situ hybridization. RESULTS: We found that the expression of TrkA and p75 receptors (p=0.03) and its ratio (p=0.0004) depends on the sensitivity of AA and GB cells to treatment with NGF and its combinations with cisplatin or temozolomide. NGF reduces (p<0.05) the quantity of MB cells with six or eight copies of MYCN and three or eight copies of MYCC. Besides, NGF increases (p<0.05) the quantity of MB cells containing two copies of both oncogenes. The negative correlation (r=-0.65, p<0.0001) is established between MYCC average copy numbers and CI of NGF in MB cells. CONCLUSIONS: The relative expression of NGF receptors (TrkA/p75) and its correlation with CI of NGF and its combinations in AA and GB cells point to the mechanism involving a cell death signaling pathway. NGF downregulates (p<0.05) some increased copy numbers of MYCC and MYCN in the human MB cell cultures, and upregulates normal two copies of both oncogenes (p<0.05).

Cytotoxic effects of chemotherapeutic drugs and heterocyclic compounds at application on the cells of primary culture of neuroepithelium tumors.

Neuroepithelial tumor cells were cultured in vitro. The biopsy material was taken from 93 children at removal of the brain tumors during neurosurgical operations. The individual features of the cells sensitivity of primary cultures in respect to protocol-approved chemotherapy drugs and changes in the Interleukin-6 (Il-6) level in the culture medium after the application of chemotherapy were established. The initial level of Il-6 exceeded 600.0 pg/ml in the cultural medium with histologically verified pilomyxoid astrocytoma cells, and ranged from 100.0 to 200.0 pg/ml in the medium at cultivation of ganglioneuroblastoma and pilocytic astrocytoma. A decrease in the Il-6 level in the medium culture of primary tumors cells was observed after the application of chemotherapeutic agents on the cells of pilomyxoid astrocytoma, astrocytomas, and pilocytic desmoplastic/nodular medulloblastoma. The production of Il-6 increased after application of cytostatic drugs on the cells of oligoastrocytomas. A decrease in Il-6 level after application of Cisplatin and Methotrexate and a 5-10 fold increase in the level of Il-6 after application of Etoposide, Carboplatin, Cytarabine, and Gemcitabine were registered in the medium with ganglioneuroblastoma. To improve the cytotoxic action of chemotherapeutic agents, the combined application of cytostatics with heterocyclic compounds was carried out. A computer modeling of ligand-protein complexes of carbamide using the Dock 6.4 and USF Chimera program packages was performed with molecular mechanics method. Special attention was drawn to the ability of several isoxazole heterocycles and isothiazolyl to inhibit the tyrosine kinase. It was proved in vitro that the joint application of chemotherapeutic agents and heterocyclic compounds could reduce the concentration of the cytostatic factor by 10 or more times, having maintained the maximum cytotoxic effect. It was assumed that the target amplification of cytotoxic action of chemotherapeutic agents had prospects for reducing toxic side effects of chemotherapy in vivo, which would be carried out only after the preclinical studies.