Role of Trypanosoma cruzi nucleoside diphosphate kinase 1 in DNA damage responses

BACKGROUND NME23/NDPKs are well conserved proteins found in all living organisms. In addition to being nucleoside diphosphate kinases (NDPK), they are multifunctional enzymes involved in different processes such as DNA stability, gene regulation and DNA repair among others. TcNDPK1 is the canonical NDPK isoform present in Trypanosoma cruzi, which has nuclease activity and DNA-binding properties in vitro. OBJECTIVES In the present study we explored the role of TcNDPK1 in DNA damage responses. METHODS TcNDPK1 was expressed in mutant bacteria and yeasts and over-expressed in epimastigotes. Mutation frequencies, tolerance to genotoxic agents and activity of DNA repair enzymes were evaluated. FINDINGS Bacteria decreased about 15-folds the spontaneous mutation rate and yeasts were more resistant to hydrogen peroxide and to UV radiation than controls. Parasites overexpressing TcNDPK1 were able to withstand genotoxic stresses caused by hydrogen peroxide, phleomycin and hidroxyurea. They also presented less genomic damage and augmented levels of poly(ADP)ribose and poly(ADP)ribose polymerase, an enzyme involved in DNA repair. MAIN CONCLUSION These results strongly suggest a novel function for TcNDPK1; its involvement in the maintenance of parasite's genome integrity.

Transcription analysis of TIMP-1 and NM23-h1 genes in glioma cell invasion / Análise transcricional dos genes TIMP-1 e NM23-H1 na invasão celular em astrocitoma difuso e glioblastoma multiforme

PURPOSE: To evaluate using transcription analysis the presence and importance of two genes: NM23-H1 and TIMP-1 on control of tumor cell invasion in diffuse astrocytomas (WHO II) and glioblastoma multiforme (WHO IV). METHOD: Northern blot analysis of NM23-H1 and TIMP-1 was performed. Eight diffuse astrocytomas and 19 glioblastomas (WHO IV) were analyzed to determine if TIMP-1 and NM23-H1 were candidates to inhibition of tumor cell invasion quantitated RNA levels. The samples were collected directly from operating room. Total cellular RNA was extracted from frozen tissue samples using guanidinium-isothiocyanate and cesium chloride gradients. Total RNA (10 mg per sample) from tumor tissue were size fractionated through 1 percent agarose-formaldehyde gel and transferred to nylon filters and then hybridized to 32P-labeled DNA probes and placed for autoradiography. Levels of specific RNAs were determined by computer-assisted laser densitometry. Blot filters were sequentially hybridized to nm23 and TIMP-1 probes in addition to GAPDH, as a control. Statistical analyses were carried out according to t-test for equality of means. RESULTS: NM23-H1 were detected in each sample, however it did not correlate with malignancy and invasiveness. On the other side TIMP-1 gene expression showed a clear correlation between low expression and invasiveness. CONCLUSION: The data suggest that TIMP-1 is an inhibitor of high grade gliomas invasion. NM23-H1 was present in the entire gliomas sample, but it did not vary in diffuse astrocytomas and glioblastomas.

OBJETIVO: Comparar através da análise da expressão dos níveis de RNA, a presença e a relevância dos genes NM23-H1 e TIMP-1 no controle da invasão celular tumoral dentro do tecido cerebral normal em: astrocitoma difuso (OMS II) e glioblastoma multiforme (OMS:IV). MÉTODO: Análise em "Northern blot" dos genes NM23-H1 e TIMP-1. Oito astrocitomas fibrilares difusos (OMS II) e 19 glioblastomas multiformes foram analisados para determinar se TIMP-1 e NM23-H1 estavam relacinados à inibição da invasão tumoral nas neoplasias do sistema nervoso central, quantificando os níveis de RNA dos respectivos genes extraídos diretamente dos tumores. 10 mg por amostra de RNA total foram fracionados de gel de formaldeído e transferidos para os filmes de hibridação. Níveis específicos de RNAs foram determinados na espectrofotometria. Valores das razões entre NM23-H1/GAPDH e TIMP-1/GAPDH foram submetidos à análise de variabilidade das médias. RESULTADOS: A análise da expressão do gene TIMP-1 mostrou supressão em tumores gliais malignos. CONCLUSÃO: Os resultados indicam que existe relação direta entre níveis baixos de TIMP-1 e malignidade dos gliomas. O gene NM23-H1 foi detectado em todas as amostras, mas não foi possível relacionar sua subexpressão ou superexpressão com algum fenótipo de invasividade.

nm23-H1 Protein Expression and Gene Mutation in 150 Patients with Non-Hodgkin's Lymphomas

The metastasis-suppressing role of the nm23 gene in the metastatic spread of malignant tumor is still debated. We examined the nm23-H1 protein expression and gene mutation in non-Hodgkin's lymphomas to compare with the clinicopathologic parameters. The expression of nm23-H1 protein was immunohistochemically examined in 150 cases of non-Hodgkin's lymphomas; 85 diffuse large B cell lymphomas (DL-BCL), 18 marginal zone B cell lymphomas (MZL), 3 mantle cell lymphomas, 25 peripheral T cell lymphomas, not otherwise specified (TCLNOS), and 19 NK/T cell lymphomas (NK/T). Eighty-one cases (58 DLBCL, 6 MZL, 4 TCLNOS, and 13 NK/T) were studied for nm23-H1 gene mutation in exon 1 to 5. The high expression of nm23-H1 protein was associated with the high IPI score (p=0.019) and the low survival rate of the patients (p=0.0039). The gene mutation of nm23-H1 was detected in 10.3% of DLBCL and 30.7% of NK/T; but none in MZL and TCLNOS. The mutation was found in exon 1 in 5 cases, exon 2 in two cases, exon 4 in one case and both exon 1 and 2 in two cases. Our results suggest that the expression of nm23-H1 protein can be used as a poor prognostic marker in non-Hodgkin's lymphomas, and the mutational change of gene may operate in the lymphomagenesis.

Cancer Metastasis and Metastasis Suppressors / 대한소화기학회지

Cancer metastasis, a complex and sequential network of cellular events involved in the migration and establishment of malignant cells from original site to distant foci, is an important and significant contributor to morbidity and mortality of cancer patients. Despite the clinical importance of cancer metastasis, its molecular and biochemical mechanism remains unclear. The identification of tumor suppressor gene confirmed that metastasis might involve the functional loss of genes that maintain the cellular differentiation optimally. Metastasis suppressor is defined by the ability to reduce the metastatic property of cancer cells without affecting its tumorigenesis. Since NM23 was first identified in 1988 as a metastasis suppressor, several metastasis suppressor genes have been identified and characterized. In this article, we review the complex and multi-step process of cancer metastasis and describe the recent progress of metastasis suppressors in the studies of identified. Consequently, we hope to introduce the new therapeutic target for the metastasis suppressors in cancer patients.