RESUMEN
BACKGROUND AND AIMS: Transketolase-like (TKTL) 1 is one of the key enzymes for anaerobic sugar degradation even in the presence of oxygen (aerobic glycolysis). Transketolase-dependent reactions supply malignant tumors with ribose and NADPH. Therefore, TKTL1 activity could be crucial for tumor proliferation and survival. The aim of the study was to evaluate the expression of TKTL1 in colorectal cancer (CRC) and its regulation under hypoxic conditions. METHODS: We studied TKTL1 mRNA and protein expression in CRC cell lines and human CRC biopsies by quantitative real-time PCR, Western blotting and immunohistochemistry. Regulation of TKTL1 under oxygen depletion was analyzed by cultivating cells either in a three-dimensional spheroid model or in a hypoxia incubator chamber. RESULTS: TKTL1 mRNA was heterogeneously expressed in monolayers of cells with high levels in HT-29 and SW480. TKTL1 protein was also clearly detectable in HT-29 and SW480. Hypoxia-inducible factor (HIF)-1α protein expression correlated with TKTL1 protein expression in SW480 spheroids over time. On the one hand, induction of hypoxia in T84 spheroids did not induce TKTL1; on the other hand, hypoxia by incubation at 1% O2 in a hypoxia incubator chamber clearly showed an upregulation of TKTL1. In 50% of CRC patients, TKTL1 protein expression was upregulated in tumor compared to non-tumor tissue. The immunohistochemical staining of TKTL1 in CRC patient samples resulted in 14 positive and 30 negative samples. CONCLUSIONS: TKTL1 expression correlated with HIF-1α protein expression and was induced upon hypoxic conditions which could facilitate energy supply to tumors under these circumstances.
Asunto(s)
Neoplasias Colorrectales/genética , Regulación Neoplásica de la Expresión Génica , Hipoxia/genética , ARN Mensajero/análisis , Transcetolasa/genética , Adulto , Anciano , Anciano de 80 o más Años , Western Blotting , Línea Celular Tumoral , Neoplasias Colorrectales/metabolismo , Femenino , Glucólisis , Células HT29 , Humanos , Hipoxia/metabolismo , Inmunohistoquímica , Masculino , Persona de Mediana Edad , Reacción en Cadena en Tiempo Real de la Polimerasa , Transcetolasa/metabolismo , Regulación hacia ArribaRESUMEN
Successful management of epilepsy still remains a vital problem. Despite using various combinations of antiepileptic drugs (AEDs), 20-25% of epileptic patients are insensitive to currently available medication. Therefore, there is a considerable need for finding a more effective AED or synergistic combinations of AEDs. Experimental and clinical data indicate that excitatory amino acid (EAA) receptor antagonists possess anticonvulsant potential. Moreover, EAA antagonists can potentiate the protective action of conventional AEDs. Unfortunately, not all beneficial (in terms of anticonvulsant activity) combinations may be recommended since some of them produce significant adverse effects which restrict their clinical use. The aim of this review was to assemble current literature data on interactions of EAA receptor antagonists with conventional AEDs. Generally, N-methyl-D-aspartate (NMDA) receptor antagonists combined with AEDs produce significant adverse effects. Non-NMDA receptor antagonists represent a more promising group.