RESUMEN
Hepatocellular carcinoma (HCC) is the most prevalent type of tumor among primary liver tumors and is the second highest cause of cancer-related deaths worldwide. Current therapies are controversial, and more research is needed to identify effective treatments. A new synthetic compound, potassium 5-cyano-4-methyl-6-oxo-1,6-dihydropyridine-2-olate (CPBMF65), is a potent inhibitor of the human uridine phosphorylase-1 (hUP1) enzyme, which controls the cell concentration of uridine (Urd). Urd is a natural pyrimidine nucleoside involved in cellular processes, such as RNA synthesis. In addition, it is considered a promising biochemical modulator, as it may reduce the toxicity caused by chemotherapeutics without impairing its anti-tumor activity. Thus, the objective of this study is to evaluate the effects of CPBMF65 on the proliferation of the human hepatocellular carcinoma cell line (HepG2). Cell proliferation, cytotoxicity, apoptosis, senescence, autophagy, intracellular Urd levels, cell cycle arrest, and drug resistance were analyzed. Results demonstrate that, after incubation with CPBMF65, HepG2 cell proliferation decreased, mainly through cell cycle arrest and senescence, increasing the levels of intracellular Urd and maintaining cell proliferation reduced during chronic treatment. In conclusion, results show, for the first time, the ability of a hUP1 inhibitor (CPBMF65) to reduce HepG2 cell proliferation through cell cycle arrest and senescence.
Asunto(s)
Antineoplásicos/farmacología , Carcinoma Hepatocelular/tratamiento farmacológico , Proliferación Celular/efectos de los fármacos , Neoplasias Hepáticas/tratamiento farmacológico , Piridinas/farmacología , Uridina Fosforilasa/antagonistas & inhibidores , Apoptosis/efectos de los fármacos , Puntos de Control del Ciclo Celular/efectos de los fármacos , Senescencia Celular/efectos de los fármacos , Cisplatino/farmacología , Resistencia a Antineoplásicos , Células Hep G2 , Humanos , Leucocitos Mononucleares/efectos de los fármacos , Uridina/farmacologíaRESUMEN
PURPOSE: 5-fluorouracil (5-FU) has been broadly used to treat solid tumors for more than 50 years. One of the major side effects of fluoropyrimidines therapy is oral and intestinal mucositis. Human uridine phosphorylase (hUP) inhibitors have been suggested as modulators of 5-FU toxicity. Therefore, the present study aimed to test the ability of hUP blockers in preventing mucositis induced by 5-FU. METHODS: We induced intestinal mucositis in Wistar rats with 5-FU, and the intestinal damage was evaluated in presence or absence of two hUP1 inhibitors previously characterized. We examined the loss of weight and diarrhea following the treatment, the villus integrity, uridine levels in plasma, and the neutrophil migration by MPO activity. RESULTS: We found that one of the compounds, 6-hydroxy-4-methyl-1H-pyridin-2-one-3-carbonitrile was efficient to promote intestinal mucosa protection and to inhibit the hUP1 enzyme, increasing the uridine levels in the plasma of animals. However, the loss of body weight, diarrhea intensity or neutrophil migration remained unaffected. CONCLUSION: Our results bring support to the hUP1 inhibitor strategy as a novel possibility of prevention and treatment of mucositis during the 5-FU chemotherapy, based on the approach of uridine accumulation in plasma and tissues.
Asunto(s)
Antimetabolitos Antineoplásicos/efectos adversos , Fluorouracilo/efectos adversos , Enfermedades Intestinales/tratamiento farmacológico , Mucositis/tratamiento farmacológico , Piridonas/uso terapéutico , Uridina Fosforilasa/antagonistas & inhibidores , Animales , Inhibidores Enzimáticos/uso terapéutico , Femenino , Humanos , Enfermedades Intestinales/inducido químicamente , Enfermedades Intestinales/metabolismo , Enfermedades Intestinales/patología , Mucosa Intestinal/efectos de los fármacos , Mucosa Intestinal/patología , Intestino Delgado/efectos de los fármacos , Intestino Delgado/metabolismo , Intestino Delgado/patología , Mucositis/inducido químicamente , Mucositis/metabolismo , Mucositis/patología , Peroxidasa/metabolismo , Ratas Wistar , Uridina/sangreRESUMEN
Uridine (Urd) is a promising biochemical modulator to reduce host toxicity caused by 5-fluorouracil (5-FU) without impairing its antitumor activity. Elevated doses of Urd are required to achieve a protective effect against 5-FU toxicity, but exogenous administration of Urd is not well-tolerated. Selective inhibitors of human uridine phosphorylase (hUP) have been proposed as a strategy to increase Urd levels. We describe synthesis and characterization of a new class of ligands that inhibit hUP type 1 (hUP1). The design of ligands was based on a possible SN1 catalytic mechanism and as mimics of the carbocation in the transition state of hUP1. The kinetic and thermodynamic profiles showed that the ligands here presented are the most potent in vitro hUP1 inhibitors developed to date. In addition, a lead compound improved the antiproliferative effects of 5-FU on colon cancer cells, accompanied by a reduction of in vitro 5-FU cytotoxicity in aggressive SW-620 cancer cells.
Asunto(s)
Antineoplásicos/farmacología , Diseño de Fármacos , Inhibidores Enzimáticos/farmacología , Fluorouracilo/farmacología , Termodinámica , Uridina Fosforilasa/antagonistas & inhibidores , Antineoplásicos/síntesis química , Antineoplásicos/química , Proliferación Celular/efectos de los fármacos , Supervivencia Celular/efectos de los fármacos , Células Cultivadas , Relación Dosis-Respuesta a Droga , Ensayos de Selección de Medicamentos Antitumorales , Inhibidores Enzimáticos/síntesis química , Inhibidores Enzimáticos/química , Fluorouracilo/síntesis química , Fluorouracilo/química , Células HT29 , Humanos , Modelos Moleculares , Estructura Molecular , Relación Estructura-Actividad , Uridina Fosforilasa/metabolismoRESUMEN
Uridine phosphorylase (UP) is a key enzyme in the pyrimidine salvage pathway, catalyzing the reversible phosphorolysis of uridine to uracil and ribose-1-phosphate (R1P). The human UP type 1 (hUP1) is a molecular target for the design of inhibitors intended to boost endogenous uridine levels to rescue normal tissues from the toxicity of fluoropyrimidine nucleoside chemotherapeutic agents, such as capecitabine and 5-fluorouracil. Here, we describe a method to obtain homogeneous recombinant hUP1, and present initial velocity, product inhibition, and equilibrium binding data. These results suggest that hUP1 catalyzes uridine phosphorolysis by a steady-state ordered bi bi kinetic mechanism, in which inorganic phosphate binds first followed by the binding of uridine, and uracil dissociates first, followed by R1P release. Fluorescence titration at equilibrium showed cooperative binding of either P(i) or R1P binding to hUP1. Amino acid residues involved in either catalysis or substrate binding were proposed based on pH-rate profiles.