RESUMO
OBJECTIVE: The objective of this study was to describe the toxicity induced by curcumin in human astrocytoma cell lines. METHODS: The effects induced by curcumin, at 100 µM for 24 h, were evaluated in four astrocytoma cell lines using crystal violet assay and through the evaluation of morphological and ultrastructural changes by electron microscopy. Also, the results of vital staining with acridine orange and propidium iodide for acidic vesicles and apoptotic bodies were analyzed and the expression of the Beclin1 gene was assessed by RT-PCR. RESULTS: The cells treated with curcumin at 100 µM induced an inhibitory concentration50 of viability with morphological changes characterized by a progressive increase in large, non-acidic vesicles devoid of cytoplasmic components and organelles, but that conserved the cell nuclei. No DNA breakage was observed. The astrocytoma cells showed no apoptosis, necrosis or autophagy. Expression of BECLIN1 was not induced (p < 0.05) by curcumin in the astrocytoma cells. CONCLUSIONS: Curcumin at 100 µm induced a new type of death cell in astrocytoma cell lines.
Assuntos
Antineoplásicos/farmacologia , Astrócitos/efeitos dos fármacos , Curcumina/farmacologia , Antineoplásicos/química , Proteínas Reguladoras de Apoptose/genética , Astrócitos/metabolismo , Astrócitos/ultraestrutura , Astrocitoma/metabolismo , Astrocitoma/patologia , Proteína Beclina-1 , Morte Celular/efeitos dos fármacos , Linhagem Celular Tumoral , Sobrevivência Celular/efeitos dos fármacos , Curcumina/química , Humanos , Concentração Inibidora 50 , Proteínas de Membrana/genética , Microscopia Eletrônica de Transmissão , Estrutura MolecularRESUMO
BACKGROUND: Abnormal expression of Rho-GTPases has been reported in several human cancers. However, the expression of these proteins in cervical cancer has been poorly investigated. In this study we analyzed the expression of the GTPases Rac1, RhoA, Cdc42, and the Rho-GEFs, Tiam1 and beta-Pix, in cervical pre-malignant lesions and cervical cancer cell lines. METHODS: Protein expression was analyzed by immunochemistry on 102 cervical paraffin-embedded biopsies: 20 without Squamous Intraepithelial Lesions (SIL), 51 Low- grade SIL, and 31 High-grade SIL; and in cervical cancer cell lines C33A and SiHa, and non-tumorigenic HaCat cells. Nuclear localization of Rac1 in HaCat, C33A and SiHa cells was assessed by cellular fractionation and Western blotting, in the presence or not of a chemical Rac1 inhibitor (NSC23766). RESULTS: Immunoreacivity for Rac1, RhoA, Tiam1 and beta-Pix was stronger in L-SIL and H-SIL, compared to samples without SIL, and it was significantly associated with the histological diagnosis. Nuclear expression of Rac1 was observed in 52.9% L-SIL and 48.4% H-SIL, but not in samples without SIL. Rac1 was found in the nucleus of C33A and SiHa cells but not in HaCat cells. Chemical inhibition of Rac1 resulted in reduced cell proliferation in HaCat, C33A and SiHa cells. CONCLUSION: Rac1 is expressed in the nucleus of epithelial cells in SILs and cervical cancer cell lines, and chemical inhibition of Rac1 reduces cellular proliferation. Further studies are needed to better understand the role of Rho-GTPases in cervical cancer progression.